Differences in immune profiles of metastatic melanoma patients treated with anti-CTLA-4 and anti-PD-1 combined immunotherapy

51

Background: Immune checkpoint inhibitors targeting the cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1) receptor have significantly improved the outcomes of metastatic melanoma patients resulting in durable response and longer overall survival. However, while some patients exhibit a complete response to immunotherapy, others have demonstrated little to no response. The aim of this study is to examine the immune cell subsets between the good and poor responders to anti-CTLA-4 and anti-PD-1 combined immunotherapy in order to determine potential mechanisms of response and resistance. Methods: Multiplex immunofluorescent staining was performed on pre-treatment formalin-fixed, paraffin-embedded (FFPE) tissue samples from good and poor responders ( n= 17; n= 11 good responders, n= 6 poor responders) for markers including CD8, PD-1, PD-L1, FOXP3 and SOX10. Spectral image analysis was conducted via the Vectra 3.0 imaging system. Quantitative analysis was carried out using the inForm software. Gene signatures associated with the T-cell signalling pathways were identified following RNA sequencing of FFPE samples. Results: Good responders displayed significantly higher levels of baseline intratumoural PD-1 and PD-L1 expression in comparison to the poor responders ( P= 0.01 and P= 0.01 respectively), highlighting their roles as predictive biomarkers of response. Additionally, the CD8+ T-cell to PD-L1 ratio was significantly higher ( P= 0.001) in the tumours of the poor responders, indicating a distinction in the CD8+ T-cell phenotypes between the good and poor responders. Furthermore, analysis of the RNA sequencing data revealed a panel of immune signatures that have been implicated in prognosis and responsiveness to immunotherapy in melanoma. Conclusions: In summary, these findings provide insight into the possible biomarkers of response and resistance to immunotherapy, thus improving our understanding of the mechanisms driving variations in response.

PD-L1 Negative Status is Associated with Lower Mutation Burden, Differential Expression of Immune-Related Genes, and Worse Survival in Stage III Melanoma

PURPOSE

Understanding why some melanomas test negative for PD-L1 by IHC may have implications for the application of anti-PD-1 therapies in melanoma management. This study sought to determine somatic mutation and gene expression patterns associated with tumor cell PD-L1 expression, or lack thereof, in stage III metastatic melanoma to better define therapeutically relevant patient subgroups.

EXPERIMENTAL DESIGN

IHC for PD-L1 was assessed in 52 American Joint Committee on Cancer stage III melanoma lymph node specimens and compared with specimen-matched comprehensive clinicopathologic, genomic, and transcriptomic data.

RESULTS

PD-L1-negative status was associated with lower nonsynonymous mutation (NSM) burden (P = 0.017) and worse melanoma-specific survival [HR = 0.28 (0.12-0.66), P = 0.002] in stage III melanoma. Gene set enrichment analysis identified an immune-related gene expression signature in PD-L1-positive tumors. There was a marked increase in cytotoxic T-cell and macrophage-specific genes in PD-L1-positive melanomas. CD8A(high) gene expression was associated with better melanoma-specific survival [HR = 0.2 (0.05-0.87), P = 0.017] and restricted to PD-L1-positive stage III specimens. NF1 mutations were restricted to PD-L1-positive tumors (P = 0.041).

CONCLUSIONS

Tumor negative PD-L1 status in stage III melanoma lymph node metastasis is a marker of worse patient survival and is associated with a poor immune response gene signature. Lower NSM levels were associated with PD-L1-negative status suggesting differences in somatic mutation profiles are a determinant of PD-L1-associated antitumor immunity in stage III melanoma. Clin Cancer Res; 22(15); 3915-23. ©2016 AACR.

Programmed death ligand 1 expression in triple-negative breast cancer is associated with tumour-infiltrating lymphocytes and improved outcome

AIMS

Triple-negative breast cancer (TNBC) patients generally have a poor outcome; there is a pressing need to identify more effective therapeutic strategies. Clinical trials targeting programmed death 1/programmed death ligand 1 (PD1/PDL1) in melanoma and non-small-cell lung cancer have reported high response rates, and tumoral PDL1 expression has been suggested as a potential biomarker to enrich for patient response to these treatments. There are only very limited data to date reporting the expression of PDL1 in TNBC.

METHODS AND RESULTS

PDL1 immunohistochemistry was performed on 161 primary TNBCs and assessed in the tumour as well as immune cells in the stromal compartment. PDL1 expression was very common in TNBC, expressed in the tumour cell membrane (64%), cytoplasm (80%) and stromal (93%) cellular compartments. Cytoplasmic tumoral expression of PDL1 was associated with a lower risk of breast cancer-specific death [hazard ratio (HR) 0.45, P = 0.035] while stromal PDL1 expression was associated with a lower rate of deaths from all causes (HR 0.305, P = 0.0042). Membranous expression of PDL1 was not associated with outcome. While both PDL1 expression and tumour-infiltrating lymphocytes were associated with a better outcome, only lymphovascular invasion and high tumour-infiltrating lymphocytes were independently prognostic for breast cancer-specific death.

CONCLUSION

While PDL1 expression is frequent in TNBC, it was not independently prognostic. There were differences in outcome depending on the cellular compartment of PDL1 expression. These data provide further impetus for investigating the utility of immune checkpoint therapies in TNBC, given the clinical significance of tumour-infiltrating lymphocytes (TILs) and PDL1 expression in this cohort.

UV-Associated Mutations Underlie the Etiology of MCV-Negative Merkel Cell Carcinomas

Merkel cell carcinoma (MCC) is an uncommon, but highly malignant, cutaneous tumor. Merkel cell polyoma virus (MCV) has been implicated in a majority of MCC tumors; however, viral-negative tumors have been reported to be more prevalent in some geographic regions subject to high sun exposure. While the impact of MCV and viral T-antigens on MCC development has been extensively investigated, little is known about the etiology of viral-negative tumors. We performed targeted capture and massively parallel DNA sequencing of 619 cancer genes to compare the gene mutations and copy number alterations in MCV-positive (n = 13) and -negative (n = 21) MCC tumors and cell lines. We found that MCV-positive tumors displayed very low mutation rates, but MCV-negative tumors exhibited a high mutation burden associated with a UV-induced DNA damage signature. All viral-negative tumors harbored mutations in RB1, TP53, and a high frequency of mutations in NOTCH1 and FAT1. Additional mutated or amplified cancer genes of potential clinical importance included PI3K (PIK3CA, AKT1, PIK3CG) and MAPK (HRAS, NF1) pathway members and the receptor tyrosine kinase FGFR2. Furthermore, looking ahead to potential therapeutic strategies encompassing immune checkpoint inhibitors such as anti-PD-L1, we also assessed the status of T-cell-infiltrating lymphocytes (TIL) and PD-L1 in MCC tumors. A subset of viral-negative tumors exhibited high TILs and PD-L1 expression, corresponding with the higher mutation load within these cancers. Taken together, this study provides new insights into the underlying biology of viral-negative MCC and paves the road for further investigation into new treatment opportunities.

Recurrent inactivating RASA2 mutations in melanoma

Analysis of 501 melanoma exomes identified RASA2, encoding a RasGAP, as a tumor-suppressor gene mutated in 5% of melanomas. Recurrent loss-of-function mutations in RASA2 were found to increase RAS activation, melanoma cell growth and migration. RASA2 expression was lost in ≥30% of human melanomas and was associated with reduced patient survival. These findings identify RASA2 inactivation as a melanoma driver and highlight the importance of RasGAPs in cancer.

Detailed pathological examination of completion node dissection specimens and outcome in melanoma patients with minimal (<0.1 mm) sentinel lymph node metastases

BACKGROUND

Nonsentinel lymph nodes (NSLNs) are rarely involved in patients with minimal volume melanoma metastases in sentinel lymph nodes (SLNs). Therefore, it has been suggested that completion lymph node dissection (CLND) is not required. However, the lack of routine immunohistochemical staining and multiple sectioning may have led to failure to identify additional positive nodes. The present study sought to more reliably determine the tumor status of NSLNs in patients with minimally involved SLNs and their clinical outcome.

METHODS

A total of 21 tumor-negative CLND specimens from 20 patients with SLN metastases of <0.1 mm in diameter treated between 1991 and 2013 were examined with a more detailed pathologic protocol (five new sections stained with/for H&E, S-100, HMB45, Melan-A, and H&E). Clinical follow-up data were also obtained.

RESULTS

Of the 343 examined NSLNs, 1 was found to harbor a 0.18-mm subcapsular sinus metastasis. No metastases were identified in the other NSLNs. Median follow-up was 48 months (range 17-130 months). Six patients (30 %) developed a recurrence. At the end of follow-up, 15 patients (75 %) were alive without sign of melanoma recurrence and 5 patients (25 %) had died of melanoma. Estimated 5-year melanoma-specific survival was 64 %. The patient with the additional positive NSLN remains without recurrence after 130 months follow-up.

CONCLUSIONS

Although the risk of additional nodal involvement is low, detailed pathologic examination may identify NSLN metastases not identified using routine protocols. Therefore, nodal clearance appears to be the safest option for these patients, pending the results of prospective trials.

Specimen quality evaluation in Canadian biobanks participating in the COEUR repository

Human biological specimens are important for translational research programs such as the Canadian Ovarian Experimental Unified Resource (COEUR) funded by the Terry Fox Research Institute. Sample quality is an important consideration, as it directly impacts the quality of ensuing research. The aim of the present study was to determine the quality of tissues collected from different sites contributing to the COEUR cohort. Samples from high-grade serous ovarian tumors (fresh frozen and corresponding paraffin-embedded tissues) were provided by nine participating Canadian biobanks. All samples were shipped to a central site using a Standard Operating Protocol (SOP). DNA and RNA extraction was conducted by the quality control division of the Canadian Tumor Repository Network (CTRNet). DNA quality was determined by ß-globin gene PCR amplification, and RNA quality by the RNA integrity number (RIN), as measured by the Agilent BioAnalyzer. DNA of acceptable quality had at least three bands of ß-globin amplified from DNA (n=115/135), and a RIN number ≥7 was considered very good for RNA (n=80/135). Sample preparation and storage time had little effect on RNA or DNA quality. Protein expression was assessed on tissue microarray by immunohistochemistry with antibodies against p53, WT1, E-cadherin, CK-7, and Ki67 from formalin fixed-paraffin embedded (FFPE) tissues. As seen with a nonhierarchical clustering statistical method, there was no significant difference in immunostaining of paraffin tissues among specimens from different biobanks. Interestingly, patients with worse outcome were highly positive for p53 and weak for WT1. In conclusion, while there was no common SOP for retrospectively collected material across Canadian biobanks, these results indicate that specimens collected at these multiple sites are of comparable quality, and can serve as an adequate resource to create a national cohort for the validation of molecular biomarkers in ovarian cancer.

Evidence for a time-dependent association between FOLR1 expression and survival from ovarian carcinoma: implications for clinical testing. An Ovarian Tumour Tissue Analysis consortium study

BACKGROUND

Folate receptor 1 (FOLR1) is expressed in the majority of ovarian carcinomas (OvCa), making it an attractive target for therapy. However, clinical trials testing anti-FOLR1 therapies in OvCa show mixed results and require better understanding of the prognostic relevance of FOLR1 expression. We conducted a large study evaluating FOLR1 expression with survival in different histological types of OvCa.

METHODS

Tissue microarrays composed of tumour samples from 2801 patients in the Ovarian Tumour Tissue Analysis (OTTA) consortium were assessed for FOLR1 expression by centralised immunohistochemistry. We estimated associations for overall (OS) and progression-free (PFS) survival using adjusted Cox regression models. High-grade serous ovarian carcinomas (HGSC) from The Cancer Genome Atlas (TCGA) were evaluated independently for association between FOLR1 mRNA upregulation and survival.

RESULTS

FOLR1 expression ranged from 76% in HGSC to 11% in mucinous carcinomas in OTTA. For HGSC, the association between FOLR1 expression and OS changed significantly during the years following diagnosis in OTTA (Pinteraction=0.01, N=1422) and TCGA (Pinteraction=0.01, N=485). In OTTA, particularly for FIGO stage I/II tumours, patients with FOLR1-positive HGSC showed increased OS during the first 2 years only (hazard ratio=0.44, 95% confidence interval=0.20-0.96) and patients with FOLR1-positive clear cell carcinomas (CCC) showed decreased PFS independent of follow-up time (HR=1.89, 95% CI=1.10-3.25, N=259). In TCGA, FOLR1 mRNA upregulation in HGSC was also associated with increased OS during the first 2 years following diagnosis irrespective of tumour stage (HR: 0.48, 95% CI: 0.25-0.94).

CONCLUSIONS

FOLR1-positive HGSC tumours were associated with an increased OS in the first 2 years following diagnosis. Patients with FOLR1-negative, poor prognosis HGSC would be unlikely to benefit from anti-FOLR1 therapies. In contrast, a decreased PFS interval was observed for FOLR1-positive CCC. The clinical efficacy of FOLR1-targeted interventions should therefore be evaluated according to histology, stage and time following diagnosis.

Evidence for a time-dependent association between FOLR1 expression and survival from ovarian carcinoma: implications for clinical testing. An Ovarian Tumour Tissue Analysis consortium study

BACKGROUND

Folate receptor 1 (FOLR1) is expressed in the majority of ovarian carcinomas (OvCa), making it an attractive target for therapy. However, clinical trials testing anti-FOLR1 therapies in OvCa show mixed results and require better understanding of the prognostic relevance of FOLR1 expression. We conducted a large study evaluating FOLR1 expression with survival in different histological types of OvCa.

METHODS

Tissue microarrays composed of tumour samples from 2801 patients in the Ovarian Tumour Tissue Analysis (OTTA) consortium were assessed for FOLR1 expression by centralised immunohistochemistry. We estimated associations for overall (OS) and progression-free (PFS) survival using adjusted Cox regression models. High-grade serous ovarian carcinomas (HGSC) from The Cancer Genome Atlas (TCGA) were evaluated independently for association between FOLR1 mRNA upregulation and survival.

RESULTS

FOLR1 expression ranged from 76% in HGSC to 11% in mucinous carcinomas in OTTA. For HGSC, the association between FOLR1 expression and OS changed significantly during the years following diagnosis in OTTA (Pinteraction=0.01, N=1422) and TCGA (Pinteraction=0.01, N=485). In OTTA, particularly for FIGO stage I/II tumours, patients with FOLR1-positive HGSC showed increased OS during the first 2 years only (hazard ratio=0.44, 95% confidence interval=0.20-0.96) and patients with FOLR1-positive clear cell carcinomas (CCC) showed decreased PFS independent of follow-up time (HR=1.89, 95% CI=1.10-3.25, N=259). In TCGA, FOLR1 mRNA upregulation in HGSC was also associated with increased OS during the first 2 years following diagnosis irrespective of tumour stage (HR: 0.48, 95% CI: 0.25-0.94).

CONCLUSIONS

FOLR1-positive HGSC tumours were associated with an increased OS in the first 2 years following diagnosis. Patients with FOLR1-negative, poor prognosis HGSC would be unlikely to benefit from anti-FOLR1 therapies. In contrast, a decreased PFS interval was observed for FOLR1-positive CCC. The clinical efficacy of FOLR1-targeted interventions should therefore be evaluated according to histology, stage and time following diagnosis.

A recurrent germline BAP1 mutation and extension of the BAP1 tumor predisposition spectrum to include basal cell carcinoma

We report four previously undescribed families with germline BRCA1-associated protein-1 gene (BAP1) mutations and expand the clinical phenotype of this tumor syndrome. The tumor spectrum in these families is predominantly uveal malignant melanoma (UMM), cutaneous malignant melanoma (CMM) and mesothelioma, as previously reported for germline BAP1 mutations. However, mutation carriers from three new families, and one previously reported family, developed basal cell carcinoma (BCC), thus suggesting inclusion of BCC in the phenotypic spectrum of the BAP1 tumor syndrome. This notion is supported by the finding of loss of BAP1 protein expression by immunochemistry in two BCCs from individuals with germline BAP1 mutations and no loss of BAP1 staining in 53 of sporadic BCCs consistent with somatic mutations and loss of heterozygosity of the gene in the BCCs occurring in mutation carriers. Lastly, we identify the first reported recurrent mutation in BAP1 (p.R60X), which occurred in three families from two different continents. In two of the families, the mutation was inherited from a common founder but it arose independently in the third family.

Specimen quality evaluation in Canadian biobanks participating in the COEUR repository

Human biological specimens are important for translational research programs such as the Canadian Ovarian Experimental Unified Resource (COEUR) funded by the Terry Fox Research Institute. Sample quality is an important consideration, as it directly impacts the quality of ensuing research. The aim of the present study was to determine the quality of tissues collected from different sites contributing to the COEUR cohort. Samples from high-grade serous ovarian tumors (fresh frozen and corresponding paraffin-embedded tissues) were provided by nine participating Canadian biobanks. All samples were shipped to a central site using a Standard Operating Protocol (SOP). DNA and RNA extraction was conducted by the quality control division of the Canadian Tumor Repository Network (CTRNet). DNA quality was determined by ß-globin gene PCR amplification, and RNA quality by the RNA integrity number (RIN), as measured by the Agilent BioAnalyzer. DNA of acceptable quality had at least three bands of ß-globin amplified from DNA (n=115/135), and a RIN number ≥7 was considered very good for RNA (n=80/135). Sample preparation and storage time had little effect on RNA or DNA quality. Protein expression was assessed on tissue microarray by immunohistochemistry with antibodies against p53, WT1, E-cadherin, CK-7, and Ki67 from formalin fixed-paraffin embedded (FFPE) tissues. As seen with a nonhierarchical clustering statistical method, there was no significant difference in immunostaining of paraffin tissues among specimens from different biobanks. Interestingly, patients with worse outcome were highly positive for p53 and weak for WT1. In conclusion, while there was no common SOP for retrospectively collected material across Canadian biobanks, these results indicate that specimens collected at these multiple sites are of comparable quality, and can serve as an adequate resource to create a national cohort for the validation of molecular biomarkers in ovarian cancer.

Hormone-receptor expression and ovarian cancer survival: an Ovarian Tumor Tissue Analysis consortium study

BACKGROUND

Few biomarkers of ovarian cancer prognosis have been established, partly because subtype-specific associations might be obscured in studies combining all histopathological subtypes. We examined whether tumour expression of the progesterone receptor (PR) and oestrogen receptor (ER) was associated with subtype-specific survival.

METHODS

12 studies participating in the Ovarian Tumor Tissue Analysis consortium contributed tissue microarray sections and clinical data to our study. Participants included in our analysis had been diagnosed with invasive serous, mucinous, endometrioid, or clear-cell carcinomas of the ovary. For a patient to be eligible, tissue microarrays, clinical follow-up data, age at diagnosis, and tumour grade and stage had to be available. Clinical data were obtained from medical records, cancer registries, death certificates, pathology reports, and review of histological slides. PR and ER statuses were assessed by central immunohistochemistry analysis done by masked pathologists. PR and ER staining was defined as negative (<1% tumour cell nuclei), weak (1 to <50%), or strong (≥50%). Associations with disease-specific survival were assessed.

FINDINGS

2933 women with invasive epithelial ovarian cancer were included: 1742 with high-grade serous carcinoma, 110 with low-grade serous carcinoma, 207 with mucinous carcinoma, 484 with endometrioid carcinoma, and 390 with clear-cell carcinoma. PR expression was associated with improved disease-specific survival in endometrioid carcinoma (log-rank p<0·0001) and high-grade serous carcinoma (log-rank p=0·0006), and ER expression was associated with improved disease-specific survival in endometrioid carcinoma (log-rank p<0·0001). We recorded no significant associations for mucinous, clear-cell, or low-grade serous carcinoma. Positive hormone-receptor expression (weak or strong staining for PR or ER, or both) was associated with significantly improved disease-specific survival in endometrioid carcinoma compared with negative hormone-receptor expression, independent of study site, age, stage, and grade (hazard ratio 0·33, 95% CI 0·21-0·51; p<0·0001). Strong PR expression was independently associated with improved disease-specific survival in high-grade serous carcinoma (0·71, 0·55-0·91; p=0·0080), but weak PR expression was not (1·02, 0·89-1·18; p=0·74).

INTERPRETATION

PR and ER are prognostic biomarkers for endometrioid and high-grade serous ovarian cancers. Clinical trials, stratified by subtype and biomarker status, are needed to establish whether hormone-receptor status predicts response to endocrine treatment, and whether it could guide personalised treatment for ovarian cancer.

FUNDING

Carraresi Foundation and others.

Low expression of the X-linked ribosomal protein S4 in human serous epithelial ovarian cancer is associated with a poor prognosis

BACKGROUND

The X-linked ribosomal protein S4 (RPS4X), which is involved in cellular translation and proliferation, has previously been identified as a partner of the overexpressed multifunctional protein YB-1 in several breast cancer cells. Depletion of RPS4X results in consistent resistance to cisplatin in such cell lines.

METHODS

As platinum-based chemotherapy is a standard first line therapy used to treat patients with ovarian cancer, we evaluated the prognostic value of RPS4X and YB-1 at the protein level in specimen from 192 high-grade serous epithelial ovarian cancer patients.

RESULTS

Immunohistochemistry studies indicated that high expression of RPS4X was associated with a lower risk of death and later disease progression (HR = 0.713, P = 0.001 and HR = 0.761, P = 0.001, respectively) as compared to low expression of RPS4X. In contrast, YB-1 was not significantly associated with either recurrence or survival time in this cohort. Finally, the depletion of RPS4X with different siRNAs in two different ovarian cancer cell lines reduced their proliferative growth rate but more importantly increased their resistance to cisplatin.

CONCLUSION

Altogether, these results suggest that the levels of RPS4X could be a good indicator for resistance to platinum-based therapy and a prognostic marker for ovarian cancer. Our study also showed that RPS4X is an independent prognostic factor in patients with serous epithelial ovarian cancer.

The genomic landscape of TP53 and p53 annotated high grade ovarian serous carcinomas from a defined founder population associated with patient outcome

High-grade ovarian serous carcinomas (HGSC) are characterized by TP53 mutations and non-random patterns of chromosomal anomalies, where the nature of the TP53 mutation may correlate with clinical outcome. However, the frequency of common somatic genomic events occurring in HGSCs from demographically defined populations has not been explored. Whole genome SNP array, and TP53 mutation, gene and protein expression analyses were assessed in 87 confirmed HGSC samples with clinical correlates from French Canadians, a population exhibiting strong founder effects, and results were compared with independent reports describing similar analyses from unselected populations. TP53 mutations were identified in 91% of HGSCs. Anomalies observed in more than 50% of TP53 mutation-positive HGSCs involved gains of 3q, 8q and 20q, and losses of 4q, 5q, 6q, 8p, 13q, 16q, 17p, 17q, 22q and Xp. Nearly 400 regions of non-overlapping amplification or deletion were identified, where 178 amplifications and 98 deletions involved known genes. The subgroup expressing mutant p53 protein exhibited significantly prolonged overall and disease-free survival as compared with the p53 protein null subgroup. Interestingly, a comparative analysis of genomic landscapes revealed a significant enrichment of gains involving 1q, 8q, and 12p intervals in the subgroup expressing mutant p53 protein as compared with the p53 protein null subgroup. Although the findings show that the frequency of TP53 mutations and the genomic landscapes observed in French Canadian samples were similar to those reported for samples from unselected populations, there were differences in the magnitude of global gains/losses of specific chromosomal arms and in the spectrum of amplifications and deletions involving focal regions in individual samples. The findings from our comparative genomic analyses also support the notion that there may be biological differences between HGSCs that could be related to the nature of the TP53 mutation.

BTN3A2 expression in epithelial ovarian cancer is associated with higher tumor infiltrating T cells and a better prognosis

BTN3A2/BT3.2 butyrophilin mRNA expression by tumoral cells was previously identified as a prognostic factor in a small cohort of high grade serous epithelial ovarian cancer (HG-EOC). Here, we evaluated the prognostic value of BT3.2 at the protein level in specimen from 199 HG-EOC patients. As the only known role of butyrophilin proteins is in immune regulation, we evaluated the association between BT3.2 expression and intratumoral infiltration of immune cells by immunohistochemistry with specific antibodies against BT3.2, CD3, CD4, CD8, CD20, CD68 and CD206. Epithelial BT3.2 expression was significantly associated with longer overall survival and lower risk of disease progression (HR=0.651, p=0.006 and HR=0.642, p=0.002, respectively) and significantly associated with a higher density of infiltrating T cells, particularly CD4+ cells (0.272, p<0.001). We also observed a strong association between the relative density of CD206+ cells, as evaluated by the ratio of intratumoral CD206+/CD68+ expression, and risk of disease progression (HR=1.355 p=0.044, respectively). In conclusion, BT3.2 protein is a potential prognostic biomarker for the identification of HG-EOC patients with better outcome. In contrast, high CD206+/CD68+ expression is associated with high risk of disease progression. While the role of BT3.2 is still unknown, our result suggest that BT3.2 expression by epithelial cells may modulates the intratumoral infiltration of immune cells.

BTN3A2 expression in epithelial ovarian cancer is associated with higher tumor infiltrating T cells and a better prognosis

BTN3A2/BT3.2 butyrophilin mRNA expression by tumoral cells was previously identified as a prognostic factor in a small cohort of high grade serous epithelial ovarian cancer (HG-EOC). Here, we evaluated the prognostic value of BT3.2 at the protein level in specimen from 199 HG-EOC patients. As the only known role of butyrophilin proteins is in immune regulation, we evaluated the association between BT3.2 expression and intratumoral infiltration of immune cells by immunohistochemistry with specific antibodies against BT3.2, CD3, CD4, CD8, CD20, CD68 and CD206. Epithelial BT3.2 expression was significantly associated with longer overall survival and lower risk of disease progression (HR = 0.651, p = 0.006 and HR = 0.642, p = 0.002, respectively) and significantly associated with a higher density of infiltrating T cells, particularly CD4+ cells (0.272, p<0.001). We also observed a strong association between the relative density of CD206+ cells, as evaluated by the ratio of intratumoral CD206+/CD68+ expression, and risk of disease progression (HR = 1.355 p = 0.044, respectively). In conclusion, BT3.2 protein is a potential prognostic biomarker for the identification of HG-EOC patients with better outcome. In contrast, high CD206+/CD68+ expression is associated with high risk of disease progression. While the role of BT3.2 is still unknown, our result suggest that BT3.2 expression by epithelial cells may modulates the intratumoral infiltration of immune cells.

Crk adaptor proteins act as key signaling integrators for breast tumorigenesis

Introduction

CT10 regulator of kinase (Crk) adaptor proteins (CrkI, CrkII and CrkL) play a role in integrating signals for migration and invasion of highly malignant breast cancer cell lines. This has important implications, as elevated CrkI/II protein levels were observed in a small cohort of breast cancer patients, which identified a potential role for Crk proteins in breast cancer progression. Numerous in vitro studies identified a role for Crk proteins in cell motility, but little is known about how Crk proteins contribute to breast cancer progression in vivo.

Methods

The clinical significance of Crk proteins in human breast cancer was assessed by analyzing published breast cancer datasets using a gene expression signature that was generated following CrkII over-expression and by examining Crk protein expression in tissue microarrays of breast tumors (n = 254). Stable knockdown of Crk (CrkI/CrkII/CrkL) proteins was accomplished using a short hairpin RNA (shRNA)-mediated approach in two basal breast cancer cell lines, MDA-231 1833TR and SUM1315, where the former have a high affinity to form bone metastases. Both in vitro assays (cell migration, invasion, soft agar growth) and in vivo experiments (intra-cardiac, tibial and mammary fat pad injections) were performed to assess the functional significance of Crk proteins in breast cancer.

Results

A gene signature derived following CrkII over-expression correlated significantly with basal breast cancers and with high grade and poor outcome in general. Moreover, elevated Crk immunostaining on tissue microarrays revealed a significant association with highly proliferative tumors within the basal subtype. RNAi-mediated knockdown of all three Crk proteins in metastatic basal breast cancer cells established a continued requirement for Crk in cell migration and invasion in vitro and metastatic growth in vivo. Furthermore, Crk ablation suppressed anchorage independent growth and in vivo orthotopic tumor growth. This was associated with diminished cell proliferation and was rescued by expression of non-shRNA targeted CrkI/II. Perturbations in tumor progression correlated with altered integrin signaling, including decreased cell spreading, diminished p130Cas phosphorylation, and Cdc42 activation.

Conclusions

These data highlight the physiological importance of Crk proteins in regulating growth of aggressive basal breast cancer cells and identify Crk-dependent signaling networks as promising therapeutic targets.

H3K27 demethylation by JMJD3 at a poised enhancer of anti-apoptotic gene BCL2 determines ERα ligand dependency

Chromatin represents a repressive barrier to the process of ligand-dependent transcriptional activity of nuclear receptors. Here, we show that H3K27 methylation imposes ligand-dependent regulation of the oestrogen receptor α (ERα)-dependent apoptotic response via Bcl-2 in breast cancer cells. The activation of BCL2 transcription is dependent on the simultaneous inactivation of the H3K27 methyltransferase, EZH2, and the demethylation of H3K27 at a poised enhancer by the ERα-dependent recruitment of JMJD3 in hormone-dependent breast cancer cells. We also provide evidence that this pathway is modified in cells resistant to anti-oestrogen (AE), which constitutively express BCL2. We show that the lack of H3K27 methylation at BCL2 regulatory elements due to the inactivation of EZH2 by the HER2 pathway leads to this constitutive activation of BCL2 in these AE-resistant cells. Our results describe a mechanism in which the epigenetic state of chromatin affects ligand dependency during ERα-regulated gene expression.

Abstract 918: A key role for Crk adaptor proteins in basal breast cancer tumor growth in vivo

Elevated levels of Crk proteins are observed in human cancers, including breast cancer, identifying a potential role for Crk in tumor progression. However, little is known about how Crk contributes to breast cancer progression in vivo. Crk proteins (CrkI, CrkII, CrkL) can regulate cell signaling downstream of integrins and various receptor tyrosine kinases through the formation of protein-protein complexes. We tested the hypothesis that Crk proteins are key signaling nodes for breast cancer tumorigenesis using shRNA-mediated knockdown of all 3 Crk proteins in highly aggressive human basal breast cancer cell lines.

Crk knockdown cells show no differences in cell proliferation under 2D culture conditions, but show significantly decreased growth in soft agar under low serum conditions. This demonstrates that Crk loss imparts a renewed dependence on adhesion and growth factor signaling in highly aggressive breast tumor cell lines and highlights a requirement for Crk dependent signals for anchorage independent growth in vitro. Consistent with this, loss of Crk in basal breast cancer cells inhibited in vivo orthotopic tumor growth in nude mice. Using immunohistochemical staining of cells 3 days post-injection, Crk knockdown diminished proliferation in vivo, but did not alter cell apoptosis when compared to controls. This difference was reflected in the formation of smaller lesions by Crk knockdown cells by 8 days post-injection. Importantly, rescue of Crk protein expression restored in vivo tumor growth, demonstrating a specific requirement for Crk proteins in this process.

To evaluate the significance of Crk in human breast cancer, immunohistochemistry was performed on two independent tissue microarrays of human breast tumors (n=209, n=234). Crk protein levels and the proliferative index were assessed by staining with antibodies to Crk and Ki67. Both Crk and Ki67 antigen positivity correlated strongly with high tumor grade (p=0.001, p=2.27e-10). Within both TMA datasets, CrkI/II (R2=0.3855, p=0.0004) and CrkL (R2=0.3845, p=0.0002) protein levels showed a strong positive correlation with cell proliferation within basal tumors, demonstrating a strong link between elevated Crk protein and an aggressive tumor phenotype. In addition to assessing Crk protein levels, a gene expression signature consisting of 151 genes was derived following Crk overexpression in a breast cancer cell line that initially had low levels of Crk. Notably, when this signature was applied to 5 breast cancer gene expression datasets (n=1469 breast cancers) there was a strong correlation with both the basal molecular subtype (p&lt;6.7e-14), and with high tumor grade (p&lt;6.4e-12), both of which are associated with poor prognosis, providing support for the IHC data.

These findings demonstrate that Crk proteins are unexpectedly essential for growth of aggressive human breast cancer cell lines in vivo, and suggest a key role for Crk proteins in basal breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 918. doi:10.1158/1538-7445.AM2011-918