Abstract P4-06-05: PanCancer profiling reveals population difference in breast cancer immune microenvironment

BACKGROUND. Breast Cancer (BC) outcome in patients (pts) of African ancestry (AA) is worse than pts of European ancestry (EA) despite accounting for socioeconomic status and access. AA have higher hormone receptor negative (HR-) and Triple Negative (TNBC) tumors, subtypes associated with stronger presence of tumor infiltrating lymphocytes (TILs). We hypothesize that BC Immune Microenvironment (IME) composition differs by ancestry, and describe IME from two independent datasets.

METHODS. Transcriptome data from the Cancer Genome Atlas (TCGA) (Group 1, Gp1) were used to estimate 22 IME cell types in BC samples by CIBERSORT. Clinical and overall survival (OS) data were accessed from XENA. Gp2 tissue samples were obtained from Women's Circle of Health study and Pathology Resource Network at Roswell Park Comprehensive Cancer Center and processed using NanoString™ PanCancer Immune Profiling panel, consisting of 770 immunity-related genes describing 24 IME cell types. Immune Dysfunction and Exclusion (TIDE) scores were derived from an algorithm by Jiang et al.

RESULTS. Gp1 consisted of 183 AA and 752 EA, with median age older in EA (54.5 vs 59). On CIBERSORT IME analysis by race, AA had higher IME infiltrates including macrophages (Mp), dendritic cells (DC) and TILs; notably T regulatory (Treg) and T Follicular Helper (Tfh) cells. The ratios of Tregs and Tfh to total TILs were also elevated. When stratified by subtypes, AAs with TNBC/Basal-like BC had higher Tregs and Tfh cells. CD8+ cells were higher in HR+ and high-grade AA pts only. CD4+/total T-cells was higher in AA across all subtypes, and predicted worse OS (HR 3.15[1.07-9.2]). Gp2 had 190 AA and 177 EA with comparable median age at diagnosis (53 versus 54) and tumor grade. By subtype, TNBC had significantly higher total TILs, CD45+, CD8+, exhausted CD8+, Treg, cytotoxic T cells, B, natural killer (NK), activated NK, DC and Mp; yet significantly lower mast cells and neutrophils (p <0.01). CD8+/Exhausted CD8+ and CD8+/Treg ratios were lower in TNBC and higher-grade tumors, and lowest in HR- grade III. Most of immune pathways were enriched in HR- tumors, with only exception being cell cycle genes being remarkably enriched in HR+ tissues (p <0.01). TIDE demonstrated high immune dysfunction in HR- and high exclusion in HR+ tumors. When compared to EA, AA had more TILs, including B, cytotoxic T-cells, exhausted CD8+, NK, activated NK and Tregs (p <0.01). Neutrophils, Mp and CD8+ were higher in EA. EA also had significantly higher ratio of immune cell types to total TILs across cytotoxic, exhausted CD8+ and Tregs, as well as persistent higher neutrophils, Mp and CD8+ ratios. CD8+/Treg ratio was higher in EA. Consistent with Gp1; CD4+/total T-cell ratio was higher in AA across all subtypes.

CONCLUSION. IME differed significantly by HR, grade and ancestry. Aggressive BC demonstrated stronger overall immune response but dysfunctional IME phenotype (higher Treg, lower granulocytes and mast cells ratios). AA had more TILs across all subtypes, but lower ratios of activator (CD8+, Cytotoxic) to suppressor TILs (Treg, exhausted CD8+), demonstrating immune tolerance and immune-desert model, exception being persistently high fraction of CD4+ ratio predicting worse OS.

Citation Format: Elkhanany A, Takabe K, Khoury T, Omilian A, Cheng D, Katsuta E, Davis W, Yan L, Hong C-C, Bandera E, Ambrosone C, Yao S. PanCancer profiling reveals population difference in breast cancer immune microenvironment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-05.

Abstract P1-09-09: Octogenerian breast cancer was associated with higher infiltration of M2 macrophages and tregs and worse disease free survival

Backgrounds: It is known that elderly patients have worse prognosis of breast cancer and commonly the blame is on their medical comorbidities and access to care. We question this dogma and hypothesized that extreme elderly (octogenerians over 80 years old) have biologically worse cancer that can be defined by mutation load, tumor heterogeneity, and its tumor immune microenvironment.

Patients and Methods: Two groups; Control (patients aged 40-65), and octogenerians (age over 80) at the time of breast cancer diagnosis were compared in The Cancer Genomic Atlas (TCGA; n=1093) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n=2506) cohorts. Cytolytic activity score (CYT), CIBERSORT analysis, tumor mutation load, as well as mutant-allele tumor heterogeneity (MATH) score were conducted as previously published.

Results: The total number of patients in the control group and octogenarians were 675 and 54 in TCGA, and 1001 and 121 in METABRIC, respectively. Octogenerians had significantly worse disease free survival in addition to overall survival in both cohorts (p<0.01 in both), which suggested that they had worse cancer biology. In terms of subtypes, octogenerians had significantly higher rate of ER positive cancers than control group in both cohorts (75.3% vs 87.0%, p<0.01 in TCGA, 72.9% vs 90.0%, p<0.01 in METABRIC), but there was no significant deference in PgR or Her2 positivity. With regard of PAM50 classification, luminal-A and B subtypes were significantly higher in octogenarians (44.6% vs 34.7%, 31.4% vs 20.5%, respectively, p<0.01), whereas basal (7.4% vs 11.2%) and claudin-low (2.5% vs 11.8%) subtypes were significantly lower (p<0.05) in octogenarians in METBRIC cohort. Given that octogenerians had subtype with favorable prognosis, we examined whether they had higher mutation load or heterogeneity of the tumor. There were no significant difference in tumor mutation load and MATH score that reflect tumor heterogeneity in both cohorts. On the other hand, breast tumors of octogenerians were significantly associated with immune-suppressive cells, such as M2 type macrophages and regulatory T cells in both cohorts (p<0.05), whereas they were negatively associated with immune- eliminating cells, such as activated memory CD4 T-cells and M1 type of macrophages in METABRIC cohort (p<0.05). There was no significant difference in CYT in TCGA cohort.

Conclusion: Our result demonstrated that octogenerians breast tumors were infiltrated with more immune-suppressive cells that may contribute to their biologically worse behavior.

Citation Format: Okano M, Elkhanany A, Qi Q, Yan L, Takabe K. Octogenerian breast cancer was associated with higher infiltration of M2 macrophages and tregs and worse disease free survival [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-09-09.

Abstract P1-15-12: Axillary lymph node metastasis and HER2-receptor positivity significantly associate with recurrence and worse survival in breast cancer patients who achieved pathological complete response after neoadjuvant chemotherapy

BACKGROUND

Neoadjuvant chemotherapy (NAC) has become a common practice in breast cancer care since it not only expands the opportunity for breast conservation surgery, but also allows in vivo assessment of individual cancer biology. Patients who achieved pathological complete response (pCR) after NAC are known to have significantly improved outcomes than those who did not. To date, there has been no large study of factors that associate with tumor recurrence after patients had pCR following NAC. To identify such factors, we examined a cohort of 394 patients.

METHODS

Patients diagnosed during 2007-16 with clinical stage I-III breast cancer who achieved pCR following NAC were identified from clinical records at four hospitals in urban Japan. Nearly 70% of patients received standard NAC regimen, which was a combination of anthracycline and taxane, with trastuzumab added as needed. pCR was defined as no pathological evidence of invasive cancer in the breast; residual ductal carcinoma in situ (DCIS) and residual axillary lymph node metastasis were included in this study. The median follow-up time was 63 months (range = 16-161 months). Outcomes were assessed by 5-year disease-free survival (DFS) and 5-year overall survival (OS).

RESULTS

Among the 394 patients with pCR, the breast cancer subtype was as follows: Luminal – 49 (12.4%), Luminal-HER2 – 97 (24.6%), HER2 – 117 (29.7%), and TNBC – 131 (33.2%). During follow up, 28 (7.1%) of the 394 patients had experienced tumor recurrence. In univariate Cox regression analysis, each of HER2-receptor status, pre-NAC tumor size, and pre-NAC axillary lymph node status were associated with recurrence. The hazard ratios, and their 95% confidence intervals (CI) and P values for these significant factors were as follows. HER2-receptor negative vs. positive: 2.5 (CI = 1.0-5.8; P = 0.036); cT1/2 vs. cT3/4: 2.2 (CI = 1.3-6.1; P = 0.008); cN0 vs. cN1-3: 9.5 (2.2-40.7; P = 0.002). However, age (<50 vs. ≥50 y), residual DCIS, post-NAC axillary lymph node status, type of mastectomy (total vs. partial), and adjuvant radiation therapy were not associated with recurrence. Of the 28 patients with recurrence, site of first event was local for 8, and brain and visceral for 10 each. Seven of the 10 patients with brain metastasis were HER2-receptor positive. Eleven of the 28 patients with recurrence had deceased, with a median post-recurrence survival duration of 40 months (range = 2–94 months). Shorter survival was associated with HER2-receptor positivity (P = 0.003).

CONCLUSION

Axillary lymph node metastasis before rather than after NAC, and HER2-receptor positivity are associated with tumor recurrence in patients who achieved pCR in breast cancer. HER2-receptor positive patients had higher risk for brain metastasis and shorter survival. Given the extreme rarity of local recurrence after pCR, we cannot help but speculate that omitting surgical removal of pCR tissue may be permissible when pCR has been diagnosed accurately.

Citation Format: Asaoka M, Narui K, Suganuma N, Chishima T, Yamada A, Kawai S, Uenaka N, Sato E, Katsuta E, Kawaguchi T, Takabe K, Ishikawa T. Axillary lymph node metastasis and HER2-receptor positivity significantly associate with recurrence and worse survival in breast cancer patients who achieved pathological complete response after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-12.

Abstract P6-03-04: Successful development of patient-derived orthotopic xenograft models of brain and lung metastases of human breast cancer

Background: Metastatic breast cancer is the reason that we continue to lose 40,000 women every year in the US. Without appropriate pre-clinical model, success rate of clinical trials continue to suffer. Because syngeneic mouse models utilize murine neoplasm that may not represent human cancer, patient-derived xenografts (PDX) have emerged as a pre-clinical model that maintains human cancer features such as intratumoral heterogeneity. However, there is no established orthotopic PDX model for metastatic breast cancer even though the main cause of death is brain and lung metastasis. Orthotopic brain or lung PDX is expected to reproduce the original tumor microenvironment. We describe our new patient-derived metastasis orthotopic xenograft (PDMOX) mouse models of human breast cancer.

Methods: All work was performed in female NSG mice of age 8-12 m. Breast cancer metastatic tumors from brain and lung that had been passaged 3x in mammary fat pads were used. Tumors of 1 mm3 were implanted orthotopically in two forms: solid piece, or minced tissue with 3 μl Matrigel. Tumor growth was monitored by MRI.

Results: Two methods for brain PDMOX were compared. “Manual push” method implanted minced tumor through a frontal bone burr hole into right caudate putamen at 4 mm depth using forceps. “Pipette tip” method utilized either a pipetter for minced tissue or Hamilton syringe for solid tissue to inoculate tumor. One hour post-surgical survival was 37.5% (3/8) after “manual push”, and 100% (30/30) after “Pipette tip” method. All tumors engrafted in surviving mice with either method. However, the tumors formed on brain surface and parenchyma invasion was rare after “manual push” method, whereas solid tumor invaded parenchyma by “pipette tip” method. Therefore, it was no surprise to find large variation in tumor growth after “Manual push” (detection time 17±5.0 d, range: 17-26; volume 5.6±21.0 mm3, range 2.8-48.7). One mouse developed ptosis, and 2 out of 3 mice that underwent “Manual push” had sudden death. On the other hand, all mice that underwent “Pipette tip” method lived until tumor grew to 125-200 mm3, without neurological symptoms. These brain tumors could be passaged with 100% success (9/9). For right lung PDMOX, “thoracotomy” and “non-thoracotomy” methods were compared. “Thoracotomy” method implanted a solid tissue using forceps or 8-0 nylon suture, or injected minced tissue 1 mm below pleura. “Non-thoracotomy” method injected minced tissue using 23G needle. One hour post-surgical survival was 30% (9/30, 8/30) after “thoracotomy” method using forceps or suture, resp. However, survival using suture method could be significantly improved to 97% (29/30) by reducing thoracotomy length (<10 vs. ≥10 mm: t test P = 0.003). Post-operative survival was not affected by age, weight, or operation or anesthesia time. On the other hand, all mice after “non-thoracotomy” method survived, but chest wall implantation occurred in 67% (4/6) when the method was performed using a cell line.

Conclusion: By simple modifications of surgical techniques, we could establish orthotopic brain and lung xenografts of breast cancer tumors with almost zero mortality and 100% engraftment. Our novel PDMOX models can be powerful tools for preclinical studies.

Citation Format: Oshi M, Okano M, Takabe K. Successful development of patient-derived orthotopic xenograft models of brain and lung metastases of human breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-03-04.

Abstract P2-06-17: A novel interaction of AURKA with MAPK pathway in breast cancer cells as a potential therapeutic target

Background: Aurora A (AURKA) is a mitotic kinase responsible for centrosome segregation and mitotic spindle formation. In normal cells, expression of AURKA is highly regulated and is predominantly restricted to G2/M phases of the cell cycle. Unlike healthy cells, cancer cells overexpress AURKA through all phases of the cell cycle resulting in the acquisition of alternate non-mitotic functions. Little is known about cellular functions regulated by AURKA and its interaction with other signaling molecules. Here, we report a novel interaction between AURKA and the mitogen-activated protein kinase (MAPK) pathway at the level of MEK1 in breast cancer cells. This interaction may serve as a novel target as well as demonstrate by an additive cytotoxic effect of AURKA- and MEK1/2-specific inhibitors against estrogen positive (ER+) and triple negative breast cancer (TNBC) cells.

Results: We show that treatment of ER+ HER2- MCF-7, ER- HER2+ SKBR3 and ER- HER2- BT549 cells with AURKA specific inhibitors alisertib, MK8745 and Aurora A Inhibitor I resulted in over 2-fold increase in relative levels of poMEK1/2 and poERK1/2 compared to untreated controls. The activation of the MAPK pathway was rapid with changes seen within 5 min after treatment with AURKA inhibitors and was sustained for at least 48 hours. Treatment with the pan RAF inhibitor TAK-632 did not diminish alisertib-induced poERK and poMEK1/2. Alternatively, treatment with the MEK1/2 specific inhibitor PD0325901 completely abrogated alisertib-induced phosphorylation of MEK1/2 and ERK1/2. In situ proximity ligation and pull down assays demonstrated AURKA and MEK1/2 direct interaction. In vitro kinase assay showed direct phosphorylation of MEK1 by AURKA. Combined treatment of alisertib and PD0325901 in vitro revealed significant additive cytotoxic effect in MCF-7 and BT549 cells when compared to either agent used alone (p< 0.008 and p<0.011; p <0.04 and p<0.028) with early trend toward significance in survival in a BT549 xenograft breast cancer in vivo model.

Conclusions: Our data shows a novel AURKA-MEK1 interaction in breast cancer cells. In depth in vivo analysis is ongoing. The results reveal a promising new strategy for the treatment TNBC patients using a combination of AURKA and MEK1/2 inhibitors.

Citation Format: Gandhi S, Gil M, Khoury T, Takabe K, Puzanov I, Gelman I, D'Assoro A, Opyrchal M. A novel interaction of AURKA with MAPK pathway in breast cancer cells as a potential therapeutic target [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-06-17.

Abstract P5-05-01: Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer

Background: Metabolic rewiring is one of the central hallmarks of cancer progression and survival to support anabolic and energetic demands. Tumor cells constantly alter their metabolic state in response to oncogenic stimuli, nutrient availability, and interaction with immune cells however the precise regulation that precedes the metabolic alteration is poorly understood. Here we report a direct interaction of glycolytic enzyme PFKFB4 with transcriptional coregulator SRC-3. PFKFB4 functions as a critical regulator of Warburg effect and our study reveals that upon glucose stimulation PFKFB4 activates SRC-3 driving an invasive-metastatic breast cancer.

Methods: Molecular experiments were performed to understand the transcriptional activation of SRC-3 by PFKFB4 enzyme. Chromatin immunoprecipitation and gene expression studies were performed to investigate the functions of PFKFB4/SRC-3 crosstalk on transcriptional regulation. Metabolomics and isotope tracing studies were performed to identify the metabolic adaptations regulated by PFKFB4/SRC-3 in breast tumors. PFKFB4-knockout was established using CRISPR-Cas9 system and functional studies were carried out to define its role in tumor cell proliferation, invasion-migration, and breast to lung metastasis. Human breast tumor samples were evaluated to identify the clinical importance of PFKFB4/SRC-3 crosstalk in patients.

Results:Molecular studies revealed that PFKFB4 enzyme phosphorylates SRC-3 at serine 857 (S857) enhancing its transcriptional activity, whereas either suppression of PFKFB4 or ectopic expression of a phosphorylation-deficient SRC-3 mutant S857A (SRC-3S857A) significantly abolished SRC-3-mediated transcriptional output (p<0.000001). Functionally, PFKFB4-driven SRC-3 activation drives glucose flux towards the pentose phosphate pathway enabling purine synthesis by transcriptionally upregulating the expression of enzyme transketolase (TKT). Deletion of PFKFB4 by CRISPR-Cas9 system resulted in significantly reduced proliferation (p<0.05) and migration-invasion (p<0.001) compared to wildtype breast tumor cells. Ablation of SRC-3 or PFKFB4 suppressed in vivo breast tumor growth and prevents metastasis to the lung from an orthotopic setting (p<0.0001). PFKFB4 and phosphorylated SRC-3 levels are significantly increased in breast tumors (p=0.02), whereas, in patients with the basal subtype, PFKFB4 and SRC-3 drive a common protein signature that correlates with the poor survival of TNBC patients (p=0.03).

Conclusion:Our data suggest that the Warburg pathway enzyme PFKFB4 acts as a molecular fulcrum that couples sugar metabolism to transcriptional activation by stimulating SRC-3 to promote aggressive metastatic tumors. It also provides first evidence how Warburg pathway drives aggressive breast tumorigenesis by directly activating powerful oncogene SRC-3. Our work suggests that targeting the PFKFB4–SRC-3 axis may be therapeutically valuable in breast tumors that are notably dependent on glucose metabolism.

(This work is funded by grants from Susan G. Komen and NCI to S.D.)

Citation Format: Dasgupta S, Anand V, John H, Sawant Dessai A, Katsuta E, Takabe K, O'Malley B. Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-05-01.

Abstract P3-08-05: High APOBEC3C-H gene expression in tumor associates with better survival in breast cancer

Background

APOBEC3 (A3) enzymes are strong mutagenic factors. A3B has been well described as an active mutator in breast cancer, whereas the roles of the other APOBEC3s (A3A, C-H) are unclear. While mutations may directly drive cancer progression, they can indirectly suppress cancer growth by generating neoantigens. To elucidate this, we comprehensively analyzed all APOBEC3s for their association with mutations and immune activity in breast cancer.

Methods

RNA seq.-based gene expression data for 1091 primary carcinomas and 113 adjacent normal tissues was from TCGA. Patients were divided into high and low groups by top and bottom gene expression tertiles. Tumor immune features like cytolytic activity, T cell receptor (TCR) diversity, and cell fractions were quantified from gene expression data. Data for some of these features, mutation-related aspects, and survival outcomes were obtained from the Pan-Cancer Atlas. Gene expression data for 55 breast cancer cell-lines was from Cancer Cell Line Encycolpedia. Cox regression and Spearman methods were respectively used for survival and correlation analyses. Welch's t test was used for group comparison. P <0.05 was deemed significant. Hallmark gene-sets were used for enrichment analysis with recommended 25% FDR.

Results

A3B and A3C together represented most (91%) of A3 gene expression in breast cancer cell-lines. In TCGA patients, expression of only A3B was increased by 4.5x in tumors compared to normal tissue, whereas levels for other A3 genes were unchanged. Surprisingly, tumor A3B or A3A levels had no significant association with overall (OS) or disease-specific survival (DSS), whereas for each of A3C-H, higher expression was significantly associated with improved OS (hazard ratios of 0.45-0.66) or DSS (0.43-0.61). The prognostic benefit of high A3C-H expression was also seen in survival analyses of two meta-datasets of microarray-based gene expression (KMPlot and SurvExpress). A3A and A3B levels correlated with both mutation burden and neoantigen load (Spearman ρ = 0.28-0.34), which respectively were 2.0-2.9x higher in high compared to low expressors. But there was no association of expression with mutation burden or neoantigen load for A3C-H. On the other hand, A3C-H levels correlated positively with tumor leukocyte fraction (ρ = 0.29-0.70) and its lymphocyte subset (ρ = 0.20-0.50), whereas the correlation was poor for A3B (ρ = 0.10 & -0.01 respectively). Expression of genes of immune function like interferon response and complement activation was enriched in high A3C-H expressors. It was not so for A3B, for which enrichment was instead observed for cell proliferation. Both CD4 and CD8 T cells were significantly more (2.3-4.0x & 2.1-5.4x resp.), and TCR diversity significantly higher (1.3-2.1x) in A3C-H high expressors. Concordantly, for each of A3C-H, expression correlated with tumor immune cytolytic activity (ρ = 0.31-0.79), which was increased 3.1-7.9x in high compared to low expressors.

Conclusions

These findings suggest that in spite of A3C-H being known as DNA mutators, an increase in their expression confers a survival benefit in breast cancer. Their increased expression likely reflects a heightened anti-cancer immune response, and may be useful for disease prognosis and monitoring immunotherapy.

Citation Format: Asaoka M, Patnaik SK, Katsuta E, Kawaguchi T, Ishikawa T, Takabe K. High APOBEC3C-H gene expression in tumor associates with better survival in breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-05.

Abstract P2-02-04: CD73 expression regulated by estrogen signaling associates with poor prognosis in estrogen receptor (ER)-positive breast cancer

Introduction: CD73, a cell surface enzyme, catalyzes the generation of adenosine from ATP and ADP in the tumor microenvironment along with CD39. Accumulated extracellular adenosine functions as immune-suppressor, and also binds to adenosine receptors which promotes angiogenesis and cell proliferation that results in accelerate cancer progression. However, the clinical significance and molecular function of CD73 expression in breast cancer remains unclear.

Methods: Utilizing publicly available breast cancer cohorts of The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), clinical significance as well as underlying mechanisms were investigated. Molecular experiments were carried out in MCF7 cells, ER-positive breast cancer cell line, to investigate the role of estrogen signaling on CD73/CD39 expression.

Results: In treatment naïve TCGA cohort, CD73 expression level was significantly lower in ER-positive breast cancers compared to ER-negative tumors. Higher CD73 expression was associated with worse overall survival in whole cohort (p=0.021) and ER-positive tumors (p=0.003), but not in ER-negative tumors. Gene Set Enrichment Analysis revealed that estrogen response gene sets (Early; NES=-1.57, p=0.043, Late; NES=-1.61, p=0.021) were significantly enriched in CD73 low expressing ER-positive tumors, suggesting estrogen signaling may repress CD73 expression. To test this hypothesis, we analyzed the expression of CD73 and CD39 in MCF7 cells treated with estrogen, tamoxifen or both. Our data revealed that estrogen treatment suppressed CD73 and CD39 expression, whereas tamoxifen treatment enhanced expression of the genes. These findings suggest that CD73 and CD39 gene expression is suppressed by estrogen signaling, whereas binding of ER antagonists such as tamoxifen can remove the repressive effect on gene expression. On the other hand, epithelial-mesenchymal transition (EMT) (Normalized Enrichment Score; NES=2.41, p<0.001) and angiogenesis (NES=2.33, p<0.001) gene sets were significantly enriched in CD73 high expressing ER-positive tumors. CIBERSORT, which is an algorithm to estimate infiltrating immune cells by gene expression, demonstrated that CD73 high expressing ER-positive tumors have less infiltrating CD8-positive T cells, memory B cells and plasma cells, implying that CD73 high expressing tumors have immune suppressive environment, which is in agreement with the notion that CD73 high tumors are immunosuppressive. Finally, we found that CD73 expression was significantly elevated post-chemotherapy compared to tumors prior to the treatment (p=0.007), and CD73 high expression patients showed worse relapse-free survival in neoadjuvant chemotherapy patients cohort (p=0.003).

Conclusion: Molecular studies revealed that CD73 expression is regulated by estrogen signaling. Increased expression of CD73 significantly correlates with worse outcomes in ER-positive breast cancer patients. This may be due to upregulated pro-metastatic gene signatures such as EMT and angiogenesis as well as less infiltration of anti-cancer immune cells by adenosine generated by CD73 in the tumor microenvironment. Our data reveals an intriguing mechanism which may be responsible for recurrence and metastasis of ER-positive breast cancer.

Citation Format: Katsuta E, Anand V, Yan L, Dasgupta S, Takabe K. CD73 expression regulated by estrogen signaling associates with poor prognosis in estrogen receptor (ER)-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-02-04.

Abstract P3-06-16: The pattern of alpha- and beta- adrenergic receptor expression impacts breast cancer outcome

BACKGROUND. Chronic stress promotes myriad of genomic changes collectively termed conserved transcriptional response to adversity (CTRA), contributing to a pro-tumorogenic and immunosuppressive tumor microenvironment (TME). Adrenergic stimulation is one mechanism of CTRA, and adrenergic receptor (AR) modulators are currently repurposed in cancer trials. However, the impact of AR expression on TME and overall survival outcome (OS) in breast cancer (BC) remains unclear. We asked whether AR expression in tumor samples predicts prognosis in BC patients (pts) and whether it correlated to expression in normal cells.

METHODS. Public RNA expression data accessed from The Cancer Genome Atlas (TCGA), and fed to deconvolutional algorithm CIBERSORT, estimating 22 immune cell proportions. Clinical and OS data were accessed from XENA. Differential gene expression obtained for 115 CTRA genes known to correlate with stress. Cytolytic activity (CY) appended from Rooney et al.

RESULTS. 1,211 pts had clinical and genomic data, including 114 pts with normal breast (BN) samples. When compared to BC, BN samples were enriched for ARG1, PTGS2, VCAM1, CSF1, as well as all ARs (ADR A1A, A1B, A1D, A2A, A2B, A2C, B1, B2, B3). There was significant correlation between BC and BN samples in A2A, B1, B2, IFN-γ, PTGS2 (Spearman ρ -0.2, -0.27, -0.2, 0.28, 0.29, P<0.01). On survival analysis, worse OS was associated with higher expression of A1B and A2C (HR 1.1[1-1.22], 1.1[1-1.17]), while higher B1 predicted better OS (HR 0.86[0.79-0.93]). OS impact persisted after quantile separation (HR for higher to lower quantiles of A1B, A2C and B1 were 1.47[1.1-2], 1.38[1.01-1.9], 0.69[0.49-0.0.95]). Co-expression of A1B and A2C predicted significantly worse OS than either alone (HR 1.53[1.1-2.2]). Results persisted after adjusting for age. For TME analysis between quantiles, higher A1B and A2C expression correlated with higher regulatory T (Treg) cells (OR 1.42[1.1-1.86]), fewer resting and activated dendritic cells (DCs) and memory CD4+ cells, and lower CY (OR 0.81[0.64-0.9]). In comparison, higher B1 correlated with higher tumor infiltrating lymphocytes (TILs), M1 macrophages (M1), M1/M2 ratio (OR 1.45[1.14-1.84], 3.64[1.03-12.8], 1.86[1.46-2.36]), lower M2 and Treg (0.42[0.33-0.53], 0.65[0.49-0.85]), and higher CY (OR 1.89[1.49-2.38]). CY also correlated with IFN-γ, MMP9 and CSF1 (Spearman ρ 0.75, 0.59, 0.3 p<0.001). Higher M2 and lower M1/M2 ratio were independently associated with a poorer OS, persisting after control for B1 (HR 1.78[1.27-2.47], 1.5[1.08-2.08]). T-cell exhaustion (Tex) genes CD274, PDCD1, CTLA4, IDO1, LAG3 and HAVCR2 were all lower in ADR-α (OR for A1B was 0.69, 0.73, 0.68, 0.87, 0.61, 0.69) and higher in ADR-β (OR for B1 was 1.46, 1.32, 1.29, 1.42, 1.26, 1.4).

CONCLUSIONS. AR genes were similarly expressed across normal and tumor samples from BC pts. Pts with higher ADR-α expression had worse OS (higher Treg, lower CY) while higher ADR-β expression pts had better OS (higher TILs, M1, M1/M2, lower Treg, M2). Tex genes were higher in ADR-β, likely due to higher TILs. These findings illustrate the potential impact of chronic stress on TME and clinical outcome, potentially helping to discern pts who can benefit most from AR modulation.

Citation Format: Elkhanany A, Katsuta E, Repasky E, Takabe K. The pattern of alpha- and beta- adrenergic receptor expression impacts breast cancer outcome [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-06-16.

Abstract P2-01-19: Sphingosine-1-phosphate affects tumor-associated macrophages in breast cancer patients

Background: Tumor-associated macrophages (TAMs) are considered to be one of the key players in the tumor microenvironment, which regulates cancer invasion and metastases. TAMs can be divided into two phenotypes with opposite functions. While M1 macrophages are known to exert anti-tumor activity by promoting pro-inflammatory effects and immune responses such as intereukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), M2 macrophages influence an anti-inflammatory response, wound healing, and pro-tumorigenic properties. A bioactive lipid mediator, sphingosine-1-phosphate (S1P) has emerged as a key regulatory molecule in cancer progression. We previously demonstrated that S1P generated by sphingosine kinase 1 (SPHK1), is a crucial mediator of breast cancer-induced angiogenesis and lymphangiogenesis, and promotes its metastasis. In particular, we found that SPHK1 is highly expressed in HER2 negative breast cancer, and the patients who developed lymph node metastasis demonstrated significantly higher levels of S1P (J Surg Res 2016). Although we have previously reported the role of S1P in recruitment of TAMs in vivo (Cancer Res 2018), its relevance in patients is yet to be uncovered. Here, we test our hypothesis that S1P signaling affects TAMs in human patients with breast cancer.

Materials and Methods: The expression level of each enzyme-encoding gene involved in S1P production was evaluated by retrieving RNA sequencing and gene expression quantification data using the Genomics Data Commons (GDC) data portal of the The Cancer Genome Atlas cohort. Gene expression levels were derived using normalization methods provided in the DESeq2 package. We compared the difference in expression levels of tumor associated macrophage related genes, including CD68, CD163, IL-6, andTNF-α between SPHK1-high breast tissue, and SPHK1-low breast tissue in the group of HER2 negative or positive patients. Unpaired t-tests were performed to compare expression differences between SPHK1-high and SPHK1-low breast tissue. All tests were two-sided and P values < 0.05 were considered statistically significant.

Results: CD68, pan-macrophage marker, is significantly increased in SPHK1-high breast cancer tissues both in HER2 negative and positive breast cancer patients (p=<0.001, <0.01). CD163 which is a scavenger receptor that is regarded as highly specific for M2 macrophages is significantly increased in SPHK1-high breast cancer tissues in HER2 negative breast cancer patients, but not in HER2 positive breast cancer patients (p=<0.001, 0.2). IL-6, which characterize M1 phenotype is significantly increased in SPHK1-high breast cancer tissues both in HER2 negative and positive breast cancer patients (p=<0.001, <0.001). TNF-α, which also characterizes M1 phenotype, is significantly increased in SPHK1-high breast cancer tissues in HER2 negative breast cancer patients, but not in HER2 positive breast cancer patients (p=<0.001, 0.05).

Conclusion: Our results suggest that S1P affects TAMs in breast cancer patients, which implicate the important roles of S1P in the complicated immune system related to tumor progression. Our results also indicate that S1P have a large role in HER2 negative breast cancer patients. Further investigations are needed to understand the underlying mechanisms.

Citation Format: Tsuchida J, Nagahashi M, Moro K, Ikarashi M, Koyama Y, Sakata J, Kobayashi T, Kameyama H, Qi Q, Yan L, Takabe K, Wakai T. Sphingosine-1-phosphate affects tumor-associated macrophages in breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-19.

Abstract P3-06-15: Young breast cancer patients demonstrate worse survival associated with aggressive oncogene expression but not with mutation load, tumor heterogeneity or pro-tumor immune cell infiltrations

INTRODUCTION: Young breast cancer patients have more aggressive subtypes and higher mortality rates. This study investigates the biologic, immunologic, and oncogenic differences between Young (≤40 yo) and Non-Young (>40 yo) patients with breast cancer.

MATERIALS/METHODS: The Cancer Genome Atlas (TCGA; n=1095) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n=1894) were used for analysis. Gene Set Enrichment Analysis (GSEA) was performed on breast cancer patients in TCGA. We calculated mutation load using both TCGA and METABRIC. We also calculated the Cytolytic Activity Score (CYT), Mutant-Allele Tumor Heterogeneity (MATH), T-Cell Receptor (TCR)-Richness, and Ki67 mRNA expression in TCGA.

RESULTS: There were 97 and 116 Young patients and 994 and 1788 Non-Young patients in the TCGA and METABRIC databases respectively. Young patients had a lower DFS (p=0.012) in TCGA. Young patients had a lower DSS (p<0.001) in METABRIC. There were less Stage I (13.5% vs 17.3%) and II (54.2% vs 58.3%) patients and more Stage III (31.2% vs 22.4%) patients in the Young group. There were more basal-like subtypes in the Young in TCGA (17.8% vs 16.1%) and METABRIC (28.4% vs 9.3%). Mutation load in TCGA was lower in the Young (p=0.030), but not significantly different in the METABRIC database. MATH, which reflects tumor heterogeneity, was not significantly different between the groups. These results were unexpected since Young patients have a higher proportion of basal-like subtype which is known to be rich in mutations and more immunogenic. In TCGA, Young patients were found to have higher amounts of activated dendritic cells (p=0.049). In METABRIC, Young patients had higher amounts of Plasma cells (p=0.016), CD4 memory-activated T-cells (p<0.001), NK resting cells (p=0.015), and M1 Macrophages (p=0.002). We also found that regulatory T-cells (p=0.029), activated NK cells (p=0.016), M2 Macrophages (p<0.001), and resting Mast cells (p=0.006) were lower in the Young. This unexpectedly showed that anti-tumor immune cells were more enriched in Young patients. Indeed, the CYT, which reflects tumor killing activity, and TCR-Richness, which reflects T-cell function, were both significantly higher in Young patients (p=0.034, p=0.004, respectively), which was opposite from what we expected due to its biological aggressiveness. GSEA was then used to analyze the TCGA database to clarify gene sets that are enriched in Young patients. Of the 50 Hallmark gene sets analyzed, 4 gene sets were found to be enriched in Young patients; G2M Checkpoint (p=0.002), Hallmark MYC Targets V1 (p=0.004), HALLMARK E2F Targets (p=0.035), and Hallmark Unfolded Protein Response (p=0.038). Ki67 which reflects cell proliferation was significantly higher in Young vs Non-Young patients (p=0.004).

CONCLUSIONS: Both TCGA and METABRIC cohorts demonstrated that Young patients have more basal-like subtype and significantly worse survival. Our results support the notion that Young patients have more aggressive cancer not because of mutations, tumor heterogeneity or immune cell infiltrations, but because of aggressive oncogene expressions.

Citation Format: Young JS, Asaoka M, Katsuta E, Kawaguchi T, Qi Q, Liu S, Yan L, Takabe K. Young breast cancer patients demonstrate worse survival associated with aggressive oncogene expression but not with mutation load, tumor heterogeneity or pro-tumor immune cell infiltrations [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-06-15.

Abstract P2-05-14: Young breast cancer patients (<40 yo) have unfavorable subtypes, higher stage and worse survival

BACKGROUND:

Over the last 40 years, the incidence of breast cancer in young women in the U.S. has been relatively low and stable, but the absolute number of young women with breast cancer is increasing because of the growing population. Some epidemiological studies have shown that breast cancer diagnosed before age 40 have significantly worse overall 5-year survival. Disease free survival is also inferior in young women, and they have more aggressive cancers in general. This study aims to validate these findings using genomic analysis of large databases.

MATERIALS AND METHODS:

The Cancer Genome Atlas (TCGA; n= 1095) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n=1894) were used for analysis. We divided the database into the Young (<40 yo) and Non-Young (>40 yo) cohorts, based on age at diagnosis. The following analysis will give the TCGA and METABRIC results in each category, respectively.

RESULTS:

There were 8.9% (98) and 6% (116) patients who were found to be Young. In the Young cohort, 69.5% (64) and 37.9% (44) were ER(+), whereas 77.9% (742) and 79.5% (1415) in the Non-Young cohort were ER(+). Further, 60.8% (56) and 31.9% (37) were PR(+) in the Young cohort, compared to 68.4% (641) and 54.4% (972) in the Non-Young cohort. Her2(+) cancers were noted in 22.2% (12) and 25% (29) in the Young cohort, whereas 22.6% (152) and 11.6% (207) were Her2(+) in the Non-Young cohort. Our group developed a pipeline to calculate PAM50 from the RNA-Seq dataset. Utilizing this calculated PAM50 in TCGA, we found that there were less Luminal A and B patients in the Young cohort, 41.6% (42) and 17.8% (18) compared to 49.7% (377) and 22.9% (174) in the Non-Young cohort. This was also the case in METABRIC where 17.2% (20) and 9.5% (11) were Luminal A and B, compared to 36.9% (659) and 25.2% (450) in the Non-Young group. In contrast, there were more basal-like subtypes in the Young group, 17.8% (18) and 28.4% (33), as compared to the Non-Young group, 16.1% (122) and 9.3% (166). These results agree with previous epidemiological studies that showed that hormone receptor positive tumors increase and basal-like subtypes decrease with age. The number of Stage I patients was lower in Young patients 13.5% (13) and 25.3% (22), than in Non-Young patients 17.3% (169) and 34.4% (453). Similarly, there were less Stage II patients in the Young 54.2% (52) and 58.6% (51) compared to 58.3% (569) and 56.9% (749) in the Non-Young. This reverses in Stage III where the incidence is increased in the Young at 31.2% (30) and 16.1% (14) compared to 22.4% (219) and 7.7% (101) in the Non-Young. Young patients had a lower median disease-free survival than Non-Young patients (NA vs 214.7 mo, p=0.027); however, there was no statistical significance in median survival. Young patients had a lower median disease-specific survival than non-young patients of 221.1 months vs 282.6 months (p=0.00123) in METABRIC.

CONCLUSION: We used large datasets to examine survival in very young breast cancer patients (<40 yo) vs older patients and found that young patients are likely to have unfavorable subtypes, higher stage, and a lower overall survival and DFS as compared to their older counterparts. Further analysis with genomics is needed.

Citation Format: Young JS, Kawaguchi T, Yan L, Qi Q, Liu S, Takabe K. Young breast cancer patients (<40 yo) have unfavorable subtypes, higher stage and worse survival [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-05-14.

Abstract P5-03-05: Sphingosine-1-phosphate produced by sphingosine kinase 1 and exported via ABCC1 shortens survival of mice and humans with breast cancer

Background: Sphingosine-1-phosphate (S1P), a bioactive sphingolipid mediator that is generated by sphingosine kinase 1 (SphK1) when it is phosphorylated (pSphK1) inside cells, has been implicated in regulation of many process important for breast cancer progression. Previously we have shown that S1P is exported out of human breast cancer cells by ATP-binding cassette (ABC) transporter ABCC1, but not by ABCB1, both known multidrug resistance proteins that efflux chemotherapeutic agents. However, the pathological consequences of these events to breast cancer progression and metastasis have not been elucidated. Here, we report that high expression of ABCC1, but not ABCB1, is associated with poor prognosis in breast cancer patients via exporting S1P.

Materials and methods: Microarray based gene expression data of 2509 patients associated with their survival were obtained from METABRIC database. Single gene survival analysis based on expressin of SphK1, and dual ABCC1 or ABCB1 and SphK1 survival analyses were perfomerd. For protein analyses, tissues were obrained from 275 patients with stage 1-3 breast cancers treated in Yokohama City University Medical Center in Japan between 2006 and 2008. The expression of pSphK1 was analyzed by immunohistochemistry and investigate the relationship with clinicopathological findings. For in vitro and in vivo experiments, breast cancer cell lines were transfected by ABCB1, ABCC1 or vector transiently or stably. BALB/c nu/nu mice and BALB/c mice were used for in vivo experiments. S1P was measured by LC-ESI-MS/MS.

Results: SphK1 expression significantly associate with worse overall survival (median survival of 124 months with high SphK1 expression compared to 163 months for patients with low SphK1 expression, p=0.0014). Although patients with high ABCC1 expression had only a slightly worse overall survival of 150 months, those with high levels of both SphK1 and ABCC1 had much worse prognosis with median overall survival of 114 months (p < 0.0068). Such association was not observed with ABCB1 expression. The frequency of strong pSphK1 protein expression was higher in HER2 enrhiched or TNBC than in Luminal. pSphK1 was more prevalent and increased in a larger tumors and in tumors from patients with lymph node metastases. Patients with breast cancers that express both pSphK1 and ABCC1 proteins have significantly shorter disease free survival. Overexpression of ABCC1, but not ABCB1, in human MCF7 and murine 4T1 cells enhanced S1P secretion, proliferation and migration of breast cancer cells. Implantation of breast cancer cells overexpressing ABCC1, but not ABCB1, into the mammary pad markedly enhanced tumor growth, angiogenesis and lymphangiogenesis with concomitant increases in lymph node and lung metastases as well as shorter survival of mice. Interestingly, S1P exported via ABCC1 from breast cancer cells upregulated transcription of SphK1 and its own formation.

Conclusions: Our findings suggest that production and export of S1P via ABCC1, but not ABCB1, is associated with worse overall and disease free survival of breast cancer patients and that S1P axis play a role in aggressive biology of breast cancer progression and metastasis.

Citation Format: Yamada A, Nagahashi M, Aoyagi T, Huang W-C, Lima S, Miyazaki H, Narui K, Ishikawa T, Endo I, Waters MR, Milstien S, Spiegel S, Takabe K. Sphingosine-1-phosphate produced by sphingosine kinase 1 and exported via ABCC1 shortens survival of mice and humans with breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-03-05.

Abstract P1-01-06: Targeting the SphK1/S1P/S1PR1 axis that connects obesity, chronic inflammation, and breast cancer metastasis

Introduction: Obesity with associated inflammation is now recognized as a risk factor for breast cancer and increased incidence of distant metastases. However, the link between obesity and breast cancer progression remains poorly understood. There is growing evidence that sphingosine-1-phosphate (S1P), a pleiotropic bioactive sphingolipid metabolite enriched both in blood and lymphatic fluid is involved in inflammation, obesity, and breast cancer progression. Our hypothesis is that obesity increases levels of S1P in both tumor and its microenvironment, which play a role in obesity-induced inflammation and breast cancer metastasis. The aim of this study is to test this hypothesis in in vitro and in vivo as well as patient settings.

Methods: Levels of sphingolipids including S1P in serum from breast cancer patients were quantified. Orthotopically-implanted E0771 syngeneic breast cancer and MMTV-PyMT transgenic breast cancer mouse models were used. Mice were fed with normal or high-fat diet (HFD). FTY720 was administered orally (1 mg/kg/day). To examine pre-metastatic niche formation, a mouse model utilizing tail vein injection of E0771 cells was used. In this model, mice were treated with conditioned media from E0771 breast cancer cells overexpressing SphK1 (K1-CM) or that from E0771 cells cultured with the vector control (CT-CM), prior to tail vein injections of naive E0771 cells. S1P levels were determined by electrospray ionization-tandem mass spectrometry.

Results: We found that obesity significantly increased S1P levels in serum from breast cancer patients. In animal breast cancer models, HFD upregulated expression of sphingosine kinase 1 (SphK1), the enzyme that produces S1P, and its receptor S1PR1 in syngeneic and spontaneous breast tumors. HFD also significantly increased S1P in breast tumors and in the tumor interstitial fluid, which is a component of the tumor microenvironment and bathes cancer cells in the tumor. Targeting the SphK1/S1P/S1PR1 axis with FTY720/fingolimod attenuated obesity-induced key pro-inflammatory cytokines, macrophage infiltration, and tumor progression. In addition, S1P produced by tumor SphK1 primed lung pre-metastatic niches, increased macrophage recruitment into the lung, and induced IL-6 and signaling pathways important for lung metastatic colonization. FTY720 suppressed HFD-induced lung IL-6 and macrophage infiltration as well as S1P-mediated signaling pathways and dramatically reduced formation of metastatic foci. In tumor bearing mice, FTY720 also suppressed obesity-related inflammation, S1P signaling, pulmonary metastasis, and prolonged survival.

Conclusion: Our results highlight a critical role for circulating S1P produced by tumor and the SphK1/S1P/S1PR1 axis in obesity-related inflammation, metastatic niche formation and breast cancer metastasis and suggest that targeting the SphK1/S1P/S1PR1 axis would be a useful therapeutic for obesity promoted metastatic breast cancer.

Citation Format: Nagahashi M, Yamada A, Aoyagi T, Huang W-C, Terracina KP, Hait N, Allegood JC, Tsuchida J, Nakajima M, Katsuta E, Milstien S, Wakai T, Spiegel S, Takabe K. Targeting the SphK1/S1P/S1PR1 axis that connects obesity, chronic inflammation, and breast cancer metastasis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-06.

Abstract P1-07-31: Integrated transcriptomics analyses identify novel three microRNAs signature to predict poor prognosis and metastasis in breast cancer

Backgrounds: MicroRNA (miRNA) play a crucial role in cancer progression, and altered miRNA expression has been demonstrated to be associated with breast cancer. MiRNA is also known to be stably detectable not only in tissue but peripheral circulation; therefore it could be a feasible and potential biomarker of breast cancer in clinical settings. However, few studies have been reported to identify promising miRNA profiles as predictive biomarker using statistically satisfied large cohorts of breast cancer patients. The aim of this study is to identify miRNA signature that can predict patient survival utilizing integrated and unbiased transcriptomics analyses.

Methods: Integrated and unbiased transcriptomics approach was conducted on genomic and clinicopathological information of 2580 breast cancer patients. We utilized The cancer Genome Atlas (TCGA) to identify miRNA signature that could significantly associated with clinical relevance including prognosis and metastatic information, followed by validation analyses with the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and Gene Expression Omnibus (GEO)

Results: A novel risk scoring model including three miRNAs signature (miR-19a, miR-93, and miR-106a) was identified using Cox model. This miRNA score was able to extract the patient population with extremely poor prognosis in TCGA (5-yr overall survival rate, 49.2 %, p=0.0005). This result was validated with another three completely independent cohorts with microarray dataset accompanied with sufficient clinical information and miRNA expression (GSE19536, n=96, p=0.0009; GSE22220, n=210, p=0.0003; METABRIC, n=1223, p=0,0023). Interestingly, the subtype stratification with PAM-50 classification using bioinformatics pipeline demonstrated that this miRNA score could predict poor overall or disease-free survival especially in the population with luminal A, B or normal like subtype (p=0.0300 and p=0.0001, respectively). In addition, competing risk analysis for tumor recurrences demonstrated that the risk scoring using three miRNAs signature could be significantly associated with bone metastasis (p=0.0052). Finally, Gene Set Enrichment Analysis (GSEA) identified that high risk score using three miRNAs associated significantly with several critical gene sets related to metastatic formation such as angiogenesis (p <0.0001), epithelial mesenchymal transition (EMT) (p = 0.0155), focal adhesion (p <0.0001), TGF-beta signaling pathway (p = 0.0025), and ECM receptor interaction (p = 0.0068).

Conclusions: We demonstrated a promising miRNAs signature score system for predicting extremely poor prognosis and metastatic potentiality in breast cancer using novel integrated transcriptomics concept.

Citation Format: Takabe K, Kawaguchi T, Yan L, Qi Q, Peng X, Young J, Liu S. Integrated transcriptomics analyses identify novel three microRNAs signature to predict poor prognosis and metastasis in breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-31.

Abstract P5-07-07: Prognostic relevance of microRNA-155 and microRNA-21 in breast cancer patients

Introduction

MicroRNAs (miRNAs) are short noncoding RNA sequences that degrade or prevent the translation of their target messenger RNA (mRNA). Altered regulation of miRNAs is implicated in different cellular processes. Some miRNAs, such as miRNA-155 (miR155) and miRNA-21 (miR21), are implicated in both immunity and cancer progression. Previous studies show that both miR155 and -21 are oncogenic, as their overexpression promotes invasion, proliferation and migration of breast cancer cells in vitro. Their overexpression within patient cohorts (n= 40-173 patients) reveals a worse prognosis for miR21 and varying associations with prognosis for miR155. By using the Cancer Genome Atlas (TCGA), which contains data from over a thousand patients, we want to clarify whether high expression of miR155 or -21 is associated with an improved or worse survival within breast tumor samples. Because both miR155 and -21 are described as oncogenic, we hypothesize that high expression of these miRNAs would portend a worse survival.

Methods

Within the breast cohort, 1052/1097 patients within TCGA contained both clinical and miRNA sequence data, acquired via the Genomic Data Common (GDC) data portal. The patients were separated into a high and low expression group for both miR155 and miR21, and associations with overall survival were obtained using the Cox proportional hazard model. Furthermore, a sub-analysis was conducted based on estrogen, progesterone and Her-2 receptor status (ER, PR, Her-2) as well as TNM staging (AJCC 7th edition).

Results

General patient characteristics within the breast cancer cohort of TCGA included: 70% Caucasian, 73% >50 years old, 75% with TNM stage I and II breast cancers, 74% ER positive, and 33% Her-2 positive. We unexpectedly found that miR155 and miR21 high expression was associated with an improved survival (p=0.05 and 0.038 respectively). In the sub-analysis, a positive association with survival was seen for miR155 high expression in ER negative, and Stage I-II breast cancers (p=0.025, 0.0013 respectively), but not in Stage III-IV. The sub-analysis for miR21 found an association with improved survival for miR21 high expression in ER negative, and stage I-II patients (p=0.033, 0.0015 respectively), but not in Stage III-IV. Although not statistically significant, a trend towards improved survival was found in ER and PR positive subgroups, for both miR155 and -21. For the Her-2 negative subgroup, there was a trend for improved survival in miR155 high expression, but not in miR21 high expression. Knowing that ER negative tumors can attract more immune cells, and that miR155 and -21 can be expressed in immune cells and tumor associated fibroblasts respectively, we speculate that their high expression was concentrated within cells from the tumor microenvironment rather than the cancer cells.

Conclusion

Using TCGA as a large validation cohort, we found that high expression of miR155 and miR21 was associated with an improved survival, which was contrary to what we predicted. Future experiments using computational biology to determine the cell type composition within the TCGA tumor samples will be performed in an effort to determine whether the tumor microenvironment influenced the survival patterns we observed in the high expression groups of miR155 and -21.

Citation Format: Kim SY, Kawaguchi T, Yan L, Young J, Qi Q, Takabe K. Prognostic relevance of microRNA-155 and microRNA-21 in breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-07-07.

Abstract P5-07-08: Survival relevance of tamoxifen sensitivity-related microRNAs, miR-342 and miR-221/222, in breast cancer patients

BACKGROUND: MicroRNAs (miRNAs) are small noncoding RNAs, which regulate the expression of target genes post-transcriptionally by RNA interference. They have emerged as one of the crucial regulators of cancer progression. Some miRNAs are reported to be related to the response of breast cancer to tamoxifen (TAM). In this study, we investigated whether the levels of TAM-resistant miRNA (miR-221/222) and TAM-sensitive miRNA (miR-342) translate to breast cancer patient survival, using multiple large databases.

MATERIALS AND METHODS: The Cancer Genome Atlas (TCGA; n=1049), Gene Expression Omnibus (GEO; GSE19536 n=96, GSE22220 n=210), and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n=2509) datasets were used and Gene Set Enrichment Analysis (GSEA) was performed.

RESULTS: MiR-342 was identified as a TAM-sensitive miRNA, and miR-221/222 were identified as TAM-resistant miRNAs by literature search. Patients with high expression of miR-342 were shown to have better survival in TCGA (OS, p=0.02; DFS, p=0.03, respectively) and in two other independent GEO cohorts (OS, p=0.02 and p=0.0007, respectively) as well as in the METABRIC cohort (OS, miR-342-3p, p=0.006; miR-342-5p, p=0.00009). By subtype analyses, high expression of miR-342 was significantly associated with better survival in ER-positive patients (p=0.04), but not in ER-negative or triple negative patients in the TCGA cohort. This association was not observed in the METABRIC cohort. Within TCGA cohort, expression of TAM-resistant miR-221/222 did not significantly impact survival. Unexpectedly, increased expression of miR-221 was shown to have increased overall survival in all patients (p=0.00904) as well as in ER-negative patients (p=0.0479) and non-triple negative patients (p=0.0106) within the METABRIC cohort. On the other hand, low expression of miR-222 was associated with increased survival of all patients (p=0.00802) as well as in non-triple negative patients (p=0.041). Lastly, GSEA demonstrated that lower miR-342 expression was significantly seen in TAM-resistant gene sets, and higher miR-342 expression was seen TAM-sensitive gene sets, but miR-221/222 did not show any significant enrichment with TAM-resistant or TAM-sensitive gene sets. Taken together with survival data, expression levels of miR-342 reflect its TAM-sensitivity related function, however, that of miR-221/222 reflect other functions in breast cancer patients.

CONCLUSION: For the first time, we used “big data” from the TCGA, GEO and METABRIC cohorts to analyze multiple miRNAs with respect to TAM sensitivities and its survival impact. We demonstrated that expression of miR-342 reflected the sensitivity of the cancer cells to TAM sensitivity, however, that of miR-221/222 reflected other functions in breast cancer patients.

Citation Format: Young JS, Kawaguchi T, Yan L, Qi Q, Liu S, Takabe K. Survival relevance of tamoxifen sensitivity-related microRNAs, miR-342 and miR-221/222, in breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-07-08.

Abstract P5-09-03: Intrinsic heterogeneity of triple-negative breast cancer cells triggers vascular mimicry in 3D matrigel matrix environment

Within the same tumor microenvironment phenotypic and functional heterogeneity arise among cancer cells as a consequence of genetic change, environmental differences, and reversible epigenetic changes in cellular properties. However, it is thought that cancer stem cells are drivers of drug resistance and metastasis. Individual tumor cells growing in culture also display heterogeneity in their intrinsic ability to progress and metastasize. It remains unclear whether intrinsic and extrinsic heterogeneity contribute to the emergence of distinct progressive phenotypes that contribute more to cancer stem cells to disseminate. To this study, we have examined the ability of matrigel to stimulate complex cell behavior that is a consequence of its heterogeneous composition. We have observed that mixing matrigel with metastatic triple negative breast cancer MDA-MB-231 cells, which mimic in vivo tumor microenvironment, around 80-90% cells created network like structures resembling a clinical phenotype known as vascular mimicry (VM) and around 10-20% cells form spheroids. BT549 another triple-negative breast cancer cells also responded similarly, forming cellular networks and spheroids when mixing with matrigel. Since CD44, a marker of epithelial-to-mesenchymal transition has shown enhances tumor aggressiveness by promoting cell plasticity, we decided to examine CD44 expression in MDA-MB-231 cells grown in 3D matrigel matrix environment. We have observed that VM forming cells are showing CD44 positive staining compared to spheroid forming cells which showed negative staining in formaldehyde-fixed 3D matrigel culture of MDA-MB-231 cells, while both group of cells stained positive for VEGFC. Next, we sought to isolate two phenotypically different groups of cells (VM and Tumorsphere forming cells) from the 3D matrigel culture by using microscopic suction procedure for gene expression analysis by qPCR. Our gene expression data suggested that VM forming cells have more expression of VM inducer genes such as CD44 and HIF1α compared to spheroid forming cells isolated from the same 3D matrigel culture of MDA-MB-231 cells. Spheroid forming cells express significant level of endothelial cell adhesion marker, CD31 compared to VM forming cells. Epigenetic mechanisms mediated suppression of tumor suppressors or anti-angiogenesis marker genes are hall mark of VM formation and cancer progression, we examine whether re-expression of those genes with Entinostat (MS-275), a selective inhibitor of class I histone deacetylase (HDAC) can abolish VM structures in 3D matrigel cell culture. Data suggested that MS-275 treatment in 3D culture drastically reduced VM structure by epigenetically re-expression of anti-angiogenic genes; SERPINF1, THBS1 and THBS2 and tumor suppressor genes; APC, PTEN and p21. While MS-275 treatment also downregulated Vimentin, VEGF-A and CD44. Our results suggest that the VM phenotype arises in a subpopulation of cells from a conserved transcriptional response in 3D matrigel environment. Epigenetically re-expression of anti-angiogenic gene expression could be a mechanism to control VM formation in triple-negative breast cancer cells.

Citation Format: Maiti A, Takabe K, Hait NC. Intrinsic heterogeneity of triple-negative breast cancer cells triggers vascular mimicry in 3D matrigel matrix environment [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-09-03.

Abstract P6-06-06: Immunogenomics approach elucidating clinical significance of DNA repair genes and tumor infiltrating immune cells in breast cancer

Backgrounds: Evading the immune system is one of the Hallmarks of Cancer. Indeed, tumor infiltrating immune cells has been shown to play critical roles in suppression of cancer progression. Genetic aberration of DNA repair genes is known to increase immunogenicity in breast cancer. However, the patient survival relevance of tumor infiltrating immune cells in regard to DNA repair genes has not yet elucidated in large cohort of breast cancer patients. We hypothesized that DNA repair gene deficiency is related to increased global genomic instability that leads to increased mutation burden, which recruits infiltrating immune cells to tumor microenvironment that result in better prognosis of breast cancer.

Patients and Methods: Integrated and unbiased transcriptomics approach was conducted on genomic and clinicopathological information of 3614 breast cancer patients. We utilized The cancer Genome Atlas (TCGA) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) to evaluate the association between the aberration of DNA repair genes and tumor infiltrating immune cell composition in breast cancer tumors, as well as its significant clinical relevance, utilizing bioinformatics and biostatistics pipelines.

Results:Low expression level of double-strand break repair genes; BRCA1, PRKDC, and RECQL4,demonstrated significantlybetter prognosis in TCGA cohort (p=0.018, p=0.036, and p=0.0002, respectively). This result was consistent in METABRIC cohort (p=0.021, p=0.00021, and p<0.000001, respectively). Utilizing CIBERSORT system that estimate the fraction of 22 immune cell types, we found that low expression of BRCA1 significantly associated with high levels of CD8 positive cell composition in both cohorts (TCGA, p=4.67E-08; METABRIC, p=0.0038), which implicate that tumor infiltrating lymphocytes are attracted to BRCA1 low expressing tumors. Further, low expression of BRCA1 showed significantly better survival in HER2 positive subtype population, but not in the other populations (TCGA, p=0.027; METABRIC, p=0.13). Finally, significantly poor prognosis was observed in breast cancers low in immune-response markers; PD-1, PD-L1, TIM3, LAG3, and CTLA4, in combination with high expression of BRCA1 (p=0.0016, p=0.0041, p=0.015, p=0.0041, and p=0.0043, respectively), which is in agreement with the dogma that intact DNA repair induce less immune-response that result is worse survival.

Conclusions: We conclude that our immunogenomics approach identify the interplay between DNA repair genes, especially gene expression of BRCA1, and tumor infiltrating immune cells, and it could have significant prognostic relevance in breast cancer.

Citation Format: Takabe K, Kawaguchi T, Yan L, Peng X, Qi Q, Okano M, Young J, Liu S. Immunogenomics approach elucidating clinical significance of DNA repair genes and tumor infiltrating immune cells in breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-06-06.

Abstract P5-05-06: Development of advanced pre-clinical in vivo models of metastatic breast cancer

Backgrounds: The fact that we continue to lose 40,000 women with breast cancer every year in the US despite the recent advance in basic research clearly demonstrate disconnect in translation of basic research findings to clinic. This is largely due to lack of appropriate animal model that mimic clinical conditions for preclinical studies that result in high failure rate of clinical trials. To date, we had established many syngeneic mouse models, which are not free from limitations; 1) few clinically relevant animal models with bone metastasis have been established, 2) syngeneic mouse model cannot address human cancer genomics and tumor heterogeneity. Patient-Derived Xenograft (PDX) model has emerged as pre-clinical model to address these issues, however, it suffers low tumor take rate of around 20-40%, and lack metastatic model. Here, we describe development of orthotopic implantation, and bone and liver metastatic breast cancer mouse models to overcome these limitations.

Methods: 1) 4T1.2-luc3 cells that has metastatic potential to the bone were orthotropically inoculated as a syngeneic mouse model, imaged with IVIS and MRI. 2) Patient tumor tissues of 1mm(3) were implanted surgically into dorsal subcutaneous space (SQ), or orthotropically into mammary fat pat #2 and #4 (MFP).

Results: 1) We established a syngeneic breast cancer bone metastasis model. Primary tumors were surgically resected days after 4T1.2-luc3 cells were orthotopically implanted under direct vision. Removal of primary tumor allowed bioluminescent visualization and quantification of bone metastasis by IVIS. We found that MRI was effective in evaluating bone metastasis and bone related events in these mice. MRI allows differentiation of bone metastasis from metastasis to the surrounding organs with bone destruction image, whereas conventional bioluminescence imaging shows only existence of cancer cells. 2) The overall tumor take rate of the tumor in PDX model was 46.0% (74/161 implantation site). Take rate from triple-negative breast cancer tumors was 56.1% (74/132), on the other hand, that from ER positive tumors was 0% (0/39). Tumor take rate was significantly better in MFP implantation than SQ (39.5%, 30/76 vs 51.2%, 44/85, p<0.01). Tumor weight were significantly heavier in MFP compared to SQ (0.072g vs 0.328g, p<0.00001). With more passage, the difference in tumor weight between SQ and MFP was significantly increased(p<0.0001). Finally, we developed a PDX breast cancer liver metastasis model by surgically implanting tissue fragment into liver using direct vision technique. We found MRI to be very useful as a living imaging modality to evaluate cancer progression in the deeply located metastatic sites of PDX models.

Conclusions: We have established orthotropic syngeneic breast cancer bone metastasis model as well as improved breast cancer PDX model with synchronous liver metastasis utilizing MRI. Our novel models could be powerful tools for preclinical studies.

Citation Format: Okano M, Kawaguchi T, Okano I, Katsuta E, Takabe K. Development of advanced pre-clinical in vivo models of metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-05-06.

Abstract P1-01-21: The levels of sphingosine-1-phosphate and its related gene expressions in breast cancer patients

Background: The bioactive lipid mediator sphingosine-1-phosphate (S1P) has emerged as a key regulatory molecule in cancer progression. We previously demonstrated that S1P is a crucial mediator of breast cancer-induced angiogenesis and lymphangiogenesis, and promote metastasis. Although increasing number of in vitro and in vivo experiments have revealed the importance of S1P in cancer progression, the data on the roles of S1P in human patients are very limited. The aim of this study is to reveal the clinical relevance of S1P in the interaction between cancer and the tumor microenvironment by examining the levels of the sphingolipids in patient breast cancer tissue samples.

Material and Method: Breast cancer tissue, peri-tumor tissue, and normal breast tissue were collected from 20 breast cancer patients immediately after surgery that were conducted from November 2015 to February 2016 at Niigata University Medical and Dental Hospital. Sphingolipids were quantified by liquid chromatography–electrospray ionization tandem mass spectrometry. The expression level of each enzyme-encoding gene involved in S1P production was evaluated by retrieving RNA sequencing and gene expression quantification data from breast cancer tissues (n = 112) and paired normal breast tissues (n = 112) using the Genomics Data Commons (GDC) data portal of the The Cancer Genome Atlas (TCGA) cohort. Gene expression levels were derived using normalization methods provided in the DESeq2 package.

Result: The levels of the sphingolipids sphingosine (Sph), dihydro-sphingosine (DHSph), S1P, and dihydro-S1P (DHS1P) were successfully determined in breast cancer, peri-tumor, and normal breast tissues from all of the 20 patients. As expected, a one-way ANOVA revealed that S1P levels were significantly different depending on the location (F(2,57) = 7.029, P = 0.002). The Tukey post hoc test revealed that S1P levels in tumors were significantly higher than those in normal breast tissue and peri-tumor tissue (P < 0.05). Similarly, Sph and DHSph levels in tumors were significantly higher than in normal breast tissue and peri-tumor tissue. Both SPHK1 and SPHK2 gene expression levels in breast cancer tissue were higher than those in normal breast tissue. Interestingly, expression of some of the S1P-related genes; S1PR3, ABCC1, SGPL1, and ORMDL2, were significantly increased in the breast cancer tissue compared to normal breast tissue. On the other hand, there was significantly decreased expression of the S1P-related genes S1PR1, S1PR2, ABCG2, SPNS2, SGPP1 and ORMDL3, in breast cancer tissue compared to normal breast tissue.

Conclusion: We demonstrated that the major source of S1P is the tumor tissue, and not the peri-tumor tissue despite the fact that angiogenesis and lymphangiogenesis are occurring more in the peri-tumor area, which implicate that S1P may have further role inside the tumor. Our results indicated the complexity of S1P signaling in human cancer than expected based on the results in vivo experiments.

Citation Format: Tsuchida J, Nagahashi M, Nakajima M, Takabe K, Wakai T. The levels of sphingosine-1-phosphate and its related gene expressions in breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-21.

Abstract P4-06-12: Murine radical mastectomy model for preclinical study of adjuvant systemic therapies

Background:

Current standard of care of breast cancer is removal of primary tumor followed by systemic adjuvant therapy to reduce recurrence and to prolong survival. However, vast majority of the preclinical studies that use murine models evaluate the drug response of primary tumors either in mammary pads or subcutaneous tissues. Lately it has been shown that the genetic profiles of metastatic lung tumors are significantly different from that of their primary mammary tumors, let alone subcutaneous tumors. Therefore we hypothesized that the responses of metastatic tumors rather than primary mammary tumors need to be evaluated for a systemic therapy. However there are few reports of murine mastectomy models used for preclinical study.

Methods:

Murine mammary adenocarcinoma 4T1-luc2 cells were inoculated into #2 right mammary fat pad under direct vision as previously described (Katsuta et al, JSR 2016). The tumor burden was quantified by bioluminescence IVIS imaging system. Novel platinum drug, Triplatin, or Vehicle was administrated every 4 days for 3 times from the day after inoculation. Amount of lung metastases were quantified ex vivo by IVIS imaging. Then we compared the growth of metastatic tumors between two methods of radical mastectomy; midline incision method and Halsted incision method, which were performed 8 days after inoculation. Triplatin or Vehicle was administered 2 days after mastectomies.

Results:

First we compared the two methods of chest mammary tumor removal; midline incision method and Halsted incision method. There was no significant difference in weight of resected tumors between these two techniques (p=0.751), however, the bioluminescence in midline incision model was significantly higher than Halsted incision model at the first day after operations (p=0.003). Only 1 out of 7 cases (14%) after Halsted incision method developed local recurrence, whereas all (100%) the animals that underwent midline incision method developed recurrence within 30 days after operation (p<0.001). No mice developed respiratory failure due to wound closure of wide skin defect. We then examined the effect of Triplatin on chest mammary tumor and lung metastasis. There was no significant difference in bioluminescence from chest mammary tumors between treatment group and non-treatment, however, ex vivo bioluminescence of lung metastases demonstrated that treatment group mice had significantly less tumor burden in lung than non-treatment group. Utilizing Halsted incision method with less local recurrence, we found that lung metastases were significantly less in treatment group than non-treatment group in live animals monitored by bioluminescence.

Conclusion:

We have established an improved murine chest mammary tumor resection model. Effects on metastases, as opposed to primary tumor should be evaluated for the preclinical study of adjuvant systemic therapy, since they may not be the same.

Citation Format: Katsuta E, Takabe K. Murine radical mastectomy model for preclinical study of adjuvant systemic therapies [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-06-12.

Abstract P3-06-07: Combination of doxorubicin with S1P signaling modulator FTY720 significantly suppressed obesity-associated breast cancer

Background:

Obesity is one of the biggest health issues in the US. It has been shown that obesity-associated breast cancer is more aggressive with poor prognosis, which is partly explained by the low-grade inflammation caused by obesity. Recently we have published that sphingosine-1-phosphate (S1P), a signaling lipid mediator, link inflammation and cancer in colitis-associated colon cancer model. We hypothesized that addition of S1P modulator that block S1P signaling thus suppress the effect of obesity-mediated inflammation should enhance anti-cancer effect of doxorubicin, which is a typical anti-cancer drug for breast cancer used as a standard of care.

Methods:

Female B6.cg-Lepob (OB/OB) mice fed with high fat diet for 2 weeks prior to implantation of cancer cells were used as an obesity model, and litter mate control mice fed with normal diet were used as a control. 1 x 106 murine mammary adenocarcinoma E0771 cells were inoculated into #2 rt. fat pads as previously described (Katsuta et al JSR 2016). 9 days after inoculation, both OB/OB and control mice were randomized into 4 groups in each group; vehicle, Doxorubicin, FTY720 and Combination of Doxorubicin and FTY720. Doxorubicin was administrated by i.p. injection at a dose of 5 mg/kg on Day 0 and 3. FTY720 was administered everyday by gavage at a dose of 1 mg/kg during the entire course. Tumor growths were measured daily by caliper measurements. Tumor weights were measured on 21 days after cell inoculation.

Results:

The body weight of obesity model was significantly heavier than control mice at the time of cancer cell inoculation (44.1 g vs 19.4 g; p < 0.001). In non-treatment group, tumor weight in obesity group was significant heavier than control mice[KT1] (1232 mg vs 966 mg; p = 0.049), which is consistent with the dogma that obesity worsen cancer progression. As expected, tumor weight in non-treatment group is heavier than any treatment group, and that in combination treatment of doxorubicin and FTY720 is lightest in both of obesity group and control group. Interestingly, tumor reduction rate in obesity group compared with non-treatment group is significant greater than control group (Doxorubicin: 83% vs 19%, p = 0.001; FTY720: 80% vs 46%, p = 0.027, Doxorubicin + FTY720: 93% vs 64%, p = 0.011). Over 15 % weight loss were seen in obesity doxorubicin group and obesity combination treatment group.

Conclusion:

Modification of S1P signaling by FTY720 was shown to enhance the effect of doxorubicin particularly in obese mice, which implicate a novel approach to treat obesity-associated breast cancer.

Citation Format: Katsuta E, Takabe K. Combination of doxorubicin with S1P signaling modulator FTY720 significantly suppressed obesity-associated breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-06-07.

A Systematic Approach to Preclinical Trials in Metastatic Breast Cancer

The process of developing new agents for therapy against breast cancer is inefficient and relies on animal models to screen for efficacy for preclinical studies. However, there has been limited validation of these models, despite the increasing costs in the rapidly growing era of personalized medicine and targeted therapy. Recently, there have been multiple studies which have critically evaluated animal models for breast cancer drug discovery. We recently reviewed the transgenic, xenograft, and syngeneic murine breast cancer models, the ectopic, orthotopic and intravenous methods of cell implantation, tumor gene expression profiles, as well as the ethics of animal experimentation, and we provide important information for investigators in this challenging field. Because of the complexities of treating breast cancer and the increasing costs of developing new agents, the choice of the appropriate murine model must carefully consider each model available, including the tumor gene expression profile. Such a critical approach to the in vivo portion of drug development will further increase the efficiency of breast cancer drug research and development.

Abstract P2-05-11: Sphingosine-1-phosphate signaling promotes metastatic niches and lung metastasis in obesity-related breast cancer

INTRODUCTION: The link between obesity and elevated breast cancer mortality is well known, however, the underlying mechanisms are poorly understood. Sphingosine-1-phosphate (S1P) is a pleiotropic bioactive lipid mediator produced by sphingosine kinases (SphKs) that plays critical roles in inflammation and cancer progression. Previously, we found that obesity increases levels of S1P not only in breast tumors, but also in the lung. "Metastatic niches" are specialized microenvironments in distant organs primed by factors from cancer cells. We hypothesized that S1P secreted from the primary tumor could promote formation of a "metastatic niche" in the lung, which assists circulating cancer cells to form metastatic lesions. Further, HFD-induced obesity increases S1P secretion from the primary tumor, which could promote the formation of "metastatic niches" in the lung and lung metastasis. The aim of this study is to test these hypotheses.

METHODS: A mouse model utilizing tail vein injection of E0771 syngeneic breast cancer cells was used. Prior to tail vein injections of naive E0771 cells, mice were treated with conditioned media from E0771 breast cancer cells overexpressing SphK1 (K1-CM) or that from E0771 cells cultured with the vector control (CT-CM). Histological analysis, RT-qPCR, and western blot were used.

RESULTS: The lungs after K1-CM treatment demonstrated much more infiltration of macrophages with greater IL-6 secretion than lungs from CT-CM mice in areas without metastasis. Furthermore, SphK1, S1P receptor 1 and IL-6 expression were all significantly higher in the lungs of mice treated with K1-CM than with CT-CM, suggesting that S1P secreted from the primary tumor promotes formation of a metastatic niche in the lung. Next, mice were fed with HFD or ND for 12 weeks before treatment with SphK1-CM, and lungs were examined 7 days after intravenous injection of E0771 cells. Histological analysis demonstrated that there were significantly more lung metastases in mice on HFD than in mice on ND. Importantly, treatment with FTY720, a functional antagonist of S1P receptor 1, significantly reduced the lung metastases in HFD fed animals. Immunofluorescent staining revealed higher expression of IL-6 and greater number of F4/80 positive macrophages in mice fed with HFD compared with mice fed with ND, whereas FTY720 dramatically suppressed both IL-6 and macrophage infiltration in the lung of HFD-fed mice. HFD-induced obesity also increased pERK, pAKT, pStat3, and pp65 in the lung, and FTY720 suppressed these signaling pathways.

CONCLUSION: Our results suggest that S1P plays a role in the formation of "metastatic niches" in the lung and lung metastasis of breast cancer, and obesity promotes this process. S1P will be a promising target for treatment of breast cancer metastasis, especially in condition with obesity. This work was supported by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research Grant Number 15H05676 and 15K15471 for M.N and 15H04927 for W.T. M.N. is supported by the Uehara Memorial Foundation, Nakayama Cancer Research Institute, and Tsukada Medical Foundation. K.T. is supported by NIH/NCI grant R01CA160688 and Susan G. Komen Investigator Initiated Research Grant IIR12222224.

Citation Format: Nagahashi M, Tsuchida J, Moro K, Tatsuda K, Koyama Y, Takabe K, Wakai T. Sphingosine-1-phosphate signaling promotes metastatic niches and lung metastasis in obesity-related breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-05-11.

Abstract P6-06-27: Expression of ATP-binding cassette transporter C1 (ABCC1) and activated sphingosine kinase 1 in breast cancer are associated with significantly shorter disease free survival

Background and specific objectives: ATP-binding cassette (ABC) transporters are known to be multidrug resistance proteins that efflux various compounds out of cells including chemotherapeutic agents. A number of clinical trails have been conducted targeting ABCB1: however, none showed beneficial effects. The pleiotropic bioactive lipid mediator sphingosine-1-phosphate (S1P), which is generated by sphingosine kinase 1 (SphK1) inside breast cancer cells and exerts its functions by binding to its specific cell surface G-protein coupled receptors (S1PR1-5) after being exported, is now known as a key regulatory molecule in breast cancer progression. We have previously demonstrated that ABCC1 and ABCG2, but not ABCB1 export S1P out of MCF7 human breast cancer cells. We hypothesized that ABCC1 expression in the presence of S1P produced by activated SphK1 in human breast cancer is associated with poor prognosis.

Methods: We constructed a tissue microarray with 281 breast tumors from patients, and analyzed expressions of ABCB1, ABCC1, and ABCG2, activated SphK1 (pSphK1), and S1P receptor-1 (S1PR1) immunohistochemically. Breast cancer subtypes were determined by immunohistochemistry of ER, PR, and HER2. Protein expressions were correlated to clinicopathological characteristics, clinical follow-up, and pathological complete response to neoadjuvant chemotherapy. For in vitro experiments, MCF7 human breast cancer cells were transfected with ABCB1 or ABCC1 and stimulated with estradiol. Cell proliferation was analyzed by WST-8 assay.

Results: The tissue microarray was comprised of 191 luminal A (68.0%), 17 luminal B (6.0%), 27 HER2 (9.6%), and 46 triple-negative (16.4%) tumors. Activated SphK1 was highly expressed in the patients with lymph node metastasis (40.1% vs 27.3%, P = 0.037) and the pSphK1 high expression group had significantly shorter disease free survival (DFS) (P = 0.05). Eighty percent of the patients expressed S1PR1; however, there were no significant differences in prognosis. On the other hand, ABCC1 expression was associated with significantly shorter DFS (P = 0.027). ABCC1 and ABCG2, but not ABCB1, were significantly higher and more frequently expressed in aggressive subtypes. Patients with tumors expressing both pSphK1 and ABCC1 had significantly shorter DFS (P = 0.002), while patients expressing both ABCB1 and pSphK1 did not. Overexpression of ABCC1 in MCF7 cells not only increased S1P secretion, it significantly increased estradiol-dependent proliferation, compared to MCF7 cells transfected with control vector or ABCB1 (P = 0.010 and P = 0.027, respectively).

Conclusions: We have shown that ABCC1 and ABCG2 are highly expressed in aggressive breast cancer subtypes, and that co-expression of pSphK1 and ABCC1 in the tumors is associated with poor prognosis. Our results suggest that inside-out signaling of S1P via ABCC1 may play a significant role in the course of human breast cancer progression.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-27.

Abstract P2-05-06: Does the lipid mediator sphingosine-1-phosphate have a role in obesity-related cancer progression?

INTRODUCTION: Obesity, which is the number one health risk in US ranked by the CDC, is an established independent prognostic factor for breast cancer patients. While the link between obesity and elevated breast cancer mortality is well known, the underlying mechanisms are poorly understood. The pleiotropic bioactive lipid mediator sphingosine-1-phosphate (S1P) has emerged as a key regulatory molecule in cancer progression and inflammation. S1P is generated by two sphingosine kinases, SphK1 and SphK2, and exerts its functions by binding to specific G protein-coupled receptors (S1PR1-5). We have recently shown that SphK1, but not SphK2, produces S1P that is exported from breast cancer cells, mediated by the ATP-binding cassette transporter, ABCC1. Furthermore, we discovered that another S1P transporter, Spns2, is important for the lymphatic network formation in the LNs. FTY720, which after phosphorylation is a S1PR1 functional antagonist, was recently approved by FDA for multiple sclerosis. FTY720 also has been suggested to have some anti-cancer actions. Our hypothesis is that obesity up-regulates SphK1, which produces more S1P; the elevated levels of S1P in both tumor and its microenvironment stimulate breast cancer progression. FTY720 is expected to disrupt the SphK1/S1P/S1PR1 axis, which is strengthened by obesity, and to reduce cancer metastasis and prolong survival. We tested our hypothesis by utilizing animal models of breast cancer with obesity treated with FTY720.

METHODS: We utilized two different syngeneic breast cancer mouse models: 4T1-luc2 cells in BALB/c mice and E0771 cells in C57Bl/6 mice, both inoculated into mammary fat pads of mice fed with normal or high fat diet. FTY720 was given orally. Western blot, QPCR and LC-ESI-MS/MS assays were used.

RESULTS: We observed that breast tumors in obese animals expressed higher levels of SphK1 and S1P transporters, such as ABCC1 and Spns2, as compared to animals on a normal diet. The levels of S1P in the plasma of obese mice were also elevated, which appears to be a consequence of the higher production of S1P by SphK1 in the tumor and its microenvironment. Importantly, tumor progression in both models was suppressed significantly by administration of FTY720. Interestingly, the cancer progression was suppressed more efficiently in the obese mice than the lean mice. Further, LC-ESI-MS/MS analysis showed that FTY720 suppressed S1P levels not only in the blood, but also in the tumor interstitial fluid.

CONCLUSIONS: These results suggest that the S1P axis is strengthened by obesity, and has a role in cancer progression. Targeting the S1P axis with FTY720 may be useful for treating breast cancer in individuals with obesity. M.N. is a Japan Society for the Promotion of Science Postdoctoral Fellow. This work was supported by NIH grants R37GM043880, R01CA61774 (to S.S.) and R01CA160688 (to K.T.).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-05-06.

Subcellular localization of fructosyl amino acid oxidases in peroxisomes of Aspergillus terreus and Penicillium janthinellum

Fructosyl amino acid oxidase (FAOD) is the enzyme catalyzing the oxidative deglycation of Amadori compounds, such as fructosyl amino acids, yielding the corresponding amino acids, glucosone, and H(2)O(2). In a previous report, we determined the primary structures of cDNAs coding for FAODs from two fungal strains Aspergillus terreus AP1 and Penicillium janthinellum and we found that both fungal FAODs included the putative peroxisome targeting signal 1 (PTS1) at the carboxyl terminal (Yoshida, N. et al., Eur. J. Biochem., 242, 499-505, 1996). In this study, we determined the intracellular localization of FAODs in these two fungi. Subcellular fractionation experiments and immuno-electronmicroscopic observations, together with the previous findings indicated that the FAODs were localized in peroxisomes of A. terreus AP1 and P. janthinellum. These FAODs were also found to belong to a new member of "peroxisomal sarcosine oxidase family protein" in eucaryotic cells.

Xylan deposition on secondary wall of Fagus crenata fiber

Delignified and/or xylanase-treated secondary walls of Fagus crenata fibers were examined by field emission scanning electron microscopy. Microfibrils with a smooth surface were visible in the innermost surface of the differentiating fiber secondary wall. There was no ultrastructural difference between control and delignified sections, indicating that lignin deposition had not started in the innermost surface of the cell wall. There was no ultrastructural difference between control and xylanase-treated sections. Microfibrils on the outer part of the differentiating secondary wall surface had globular substances in delignified sections. These globular substances disappeared following xylanase treatment, indicating that these globules are xylan. The globular substances were not visible near the inner part of the differentiating secondary wall but gradually increased toward the outer part of the secondary wall, indicating that xylan penetrated into the cell wall and continuously accumulated on the microfibrils. Mature-fiber secondary walls were also examined by field emission scanning electron microscopy. Microfibrils were not apparent in the secondary wall in control specimens. Microfibrils with many globular substances were observed in the delignified specimens. Following xylanase treatment, the microfibrils had a smooth surface without any globules, indicating that the globular substance is xylan. These results suggest that cellulose microfibrils synthesized on the plasma membrane are released into the innermost surface of the secondary wall and coated with a thin layer of xylan. Successive deposition of xylan onto the cell wall increases the microfibril diameter. The large amounts of xylan that accumulated on microfibrils appear globular but are covered with lignin after they are deposited.

Role of the putative membrane-bound endo-1,4-beta-glucanase KORRIGAN in cell elongation and cellulose synthesis in Arabidopsis thaliana

A temperature-sensitive, elongation-deficient mutant of Arabidopsis thaliana was isolated. At the non-permissive temperature of 31 degrees C, the mutation impaired tissue elongation; otherwise, tissue development was normal. Hypocotyl cells that had established cell walls at 21 degrees C under light-dark cycles ceased elongation and swelled when the mutant was shifted to 31 degrees C and darkness, indicating that the affected gene is essential for cell elongation. Analysis of the cell walls of mutant plants grown at 31 degrees C revealed that the cellulose content was reduced to 40% and the pectin content was increased to 162% of the corresponding values for the wild type grown at the same temperature. The increased amounts of pectin in the mutant were bound tightly to cellulose microfibrils. No change in the content of hemicellulose was apparent in the 31 degrees C-adapted mutant. Field emission-scanning electron microscopy suggested that the structure of cellulose bundles was affected by the mutation; X-ray diffraction, however, revealed no change in the crystallite size of cellulose microfibrils. The regeneration of cellulose microfibrils from naked mutant protoplasts was substantially delayed at 31 degrees C. The recessive mutation was mapped to chromosome V, and map-based cloning identified it as a single G-->A transition (resulting in a Gly(429)-->Arg substitution) in KORRIGAN, which encodes a putative membrane-bound endo-1,4-beta-glucanase. These results demonstrate that the product of this gene is required for cellulose synthesis.

Autolysis during in vitro tracheary element differentiation: formation and location of the perforation

Tracheary elements differentiated from isolated Zinnia: mesophyll cells were observed at various times of culture under a scanning electron microscope. Perforation occurred on the primary wall at one of the longitudinal ends in single tracheary elements. In double tracheary elements, which both of two cells derived from a single cell differentiated into, the pore opened on the primary walls both at the junction of the two tracheary elements and at a longitudinal end of one of the two tracheary elements. These results suggest not only that a single tracheary element has its own program to form a perforation at one end without being affected by neighboring cells, but also that isolated cells indeed hold some traces of polarity and cell-cell communication.

Computed tomography (CT) findings of gastric rupture after blunt trauma

A 49-year-old carpenter was hit by timber around his upper abdomen 1 hour after breakfast. Immediate computed tomography was taken, followed by emergency laparotomy showing gastric rupture accompanied with hemorrhage from the superior mesenteric vein. Hemostasis and distal partial gastrectomy followed by Billroth-I anastomosis reconstruction was performed. Here, we report the abdominal computed tomography findings from a patient with gastric rupture after blunt trauma. The present case, which is only the second such case reported in English literature, suggested that computed tomography is useful for assessing associated injuries in gastric rupture patients, for detecting intraperitoneal free air which can be missed by X-rays, and for locating the laceration of the rupture.

Boron nutrition of cultured tobacco BY-2 cells. III. Characterization of the boron-rhamnogalacturonan II complex in cells acclimated to low levels of boron

Cultured cells of tobacco (Nicotiana tabacum L.) BY-2 which could propagate at the same rate as the parent cells (1 mg B liter(-1)) under a lower level of boron (0.01 mg B liter(-1)) were obtained. The selected cells had swollen cell walls. In the parent cells, all the RG-II occurred as a B-RG-II complex, however, two-thirds of the RG-II occurred in a monomeric form in the selected cells.

Production of fungal fructosyl amino acid oxidase useful for diabetic diagnosis in the peroxisome of Candida boidinii

A high-level production of fructosyl amino acid oxidase (FAOD), whose production was toxic in Escherichia coli, was investigated through attempts to utilize the peroxisome of Candida boidinii as the place for protein accumulation. The alcohol oxidase-depleted strain (strain aod1Delta) produced FAOD at a four to five times higher level than the wild type strain in terms of protein amount and enzyme activity, although the transcriptional level was similar. As a result of this study, we could improve FAOD productivity approximately 47-fold from the original transformant, and FAOD accumulated within membrane-bound peroxisomes up to 18% of the total soluble proteins.