Hypoxia-related carbonic anhydrase 9 induces serpinB9 expression in cancer cells and apoptosis in T cells via acidosis

Hypoxia is a common feature of solid tumors. However, the impact of hypoxia on immune cells within tumor environments remains underexplored. Carbonic anhydrase 9 (CA9) is a hypoxia-responsive tumor-associated enzyme. We previously noted that regardless of human CA9 (hCA9) expression, hCA9-expressing mouse renal cell carcinoma RENCA (RENCA/hCA9) presented as a "cold" tumor in syngeneic aged mice. This study delves into the mechanisms behind this observation. Gene microarray analyses showed that RENCA/hCA9 cells exhibited elevated mouse serpinB9, an inhibitor of granzyme B, relative to RENCA cells. Corroborating this, RENCA/hCA9 cells displayed heightened resistance to antigen-specific cytotoxic T cells compared with RENCA cells. Notably, siRNA-mediated serpinB9 knockdown reclaimed this sensitivity. In vivo tests showed that serpinB9 inhibitor administration slowed RENCA tumor growth, but this effect was reduced in RENCA/hCA9 tumors, even with adjunctive immune checkpoint blockade therapy. Further, inducing hypoxia or introducing the mouse CA9 gene upregulated serpinB9 expression, and siRNA-mediated knockdown of the mouse CA9 gene inhibited the hypoxia-induced induction of serpinB9 in the original RENCA cells. Supernatants from RENCA/hCA9 cultures had lower pH than those from RENCA, suggesting acidosis. This acidity enhanced serpinB9 expression and T cell apoptosis. Moreover, coculturing with RENCA/hCA9 cells more actively prompted T cell apoptosis than with RENCA cells. Collectively, these findings suggest hypoxia-associated CA9 not only boosts serpinB9 in cancer cells but also synergistically intensifies T cell apoptosis via acidosis, characterizing RENCA/hCA9 tumors as "cold."

Senolysis of gemcitabine-induced senescent human pancreatic cancer cells

INTRODUCTION

Gemcitabine (GEM) is often used to treat pancreatic cancer. Many anti-cancer drugs induce cancer cell death, but some cells survive after cell cycle arrest. Such a response to DNA damage is termed cellular senescence. Certain drugs, including the Bcl-2-family inhibitor ABT-263, kill senescent cells; this is termed senolysis. In this study, we examined the therapeutic benefits of ABT-263 in GEM-induced senescence of human pancreatic cancer cells.

METHODS AND RESULTS

Of four pancreatic cancer cell lines (PANC-1, AsPC-1, CFPAC-1, and PANC10.05), GEM induced senescent features in PANC-1 and AsPC-1 cells, including increases in the cell sizes and expression levels of mRNAs encoding interleukin (IL)-6/IL-8 and induction of β-galactosidase. Successive treatment with GEM and ABT-263 triggered apoptosis in PANC-1 and AsPC-1 cells and suppressed colony formation significantly. Senolysis of GEM-induced senescent pancreatic cancer cells by ABT-263 was triggered by a Bcl-xL inhibitor, but not by a Bcl-2 inhibitor, suggesting a central role for Bcl-xL in senolysis. In a xenograft mouse model, combined treatment with GEM and ABT-737 (an ABT-263 analog exhibiting the same specificity) suppressed in vivo growth of AsPC-1 significantly.

CONCLUSION

Together, our results indicate that sequential treatment with GEM and senolytic drugs effectively kill human pancreatic cancer cells.

Methoxyflavones isolated from the whole plant of Scutellaria rubropunctata Hayata var. rubropunctata promote osteoblast differentiation in MC3T3-E1 cells

In this study, we isolated two new methoxyflavones (1 and 2) and eight known methoxyflavones (3-10) from the whole plant of Scutellaria rubropunctata Hayata var. rubropunctata (SR). Based on spectroscopic analyses, the methoxyflavones were identified as 5,8,2',6'-tetramethoxy-6,7-methylenedioxyflavone (1) and 5,2',6'-trimethoxy-6,7-methylenedioxyflavone (2). We reported SR might have effects on promoting osteoblast differentiation and stimulating estrogen receptor (ER) in the previous study. Then, the effects of 1-10 on pre-osteoblast MC3T3-E1 cells were investigated, and 1, 2, and 9 were observed to promote alkaline phosphatase activity. To evaluate their effect on osteogenesis-related genes, we performed gene expression analysis using quantitative real-time PCR after treatment of MC3T3-E1 cells with these compounds. Although 2 was only effective at lower concentrations, 1 and 9 upregulated the mRNA levels of Runx2, Osterix, Osteopontin, Osteocalcin, Smad1, and Smad4. These results indicate that 1 and 9 may induce osteoblast differentiation by activating Runx2 via the BMP/Smad pathway and may play a central role in the promotion of osteoblast differentiation by SR. The ER agonist activity of 1-10 were tested using a luciferase reporter assay in HEK293 cells. However, none of the compounds exhibited remarkable activity. Thus, SR may contain other compounds that contribute to its ER agonist activity.

Effects of a Whole Plant Extract of Scutellaria rubropunctata var. rubropunctata on Bone Metabolism with Estrogen Receptor Activation

We screened natural resources for estrogen receptor (ER)-activating and bone metabolism-promoting activities with the aim of finding potential treatments for osteoporosis. A screen of 1531 extracts from Ryukyu Arc plants using a luciferase reporter assay identified an 80% MeOH extract of Scutellaria rubropunctata var. rubropunctata (SRE) with dose-dependent ER transcription-promoting activity. Importantly, SRE had no proliferative effect on human breast cancer cells. SRE enhanced the ALP activity of pre-osteoblast MC3T3-E1 cells after 72 h in culture and slightly enhanced mineralization at 14 and 21 d. SRE did not significantly affect the TRAP activity of RAW264.7 cells. Gene expression analysis in MC3T3-E1 cells by quantitative real-time PCR revealed that SRE upregulated the mRNA levels of Runx2, Osterix (Osx), Osteopontin (Opn), Osteocalcin (Ocn), Smad1, Smad4, and Smad5 at 72 h, and those of Runx2, Osx, Smad1, Smad4, and Smad5 at 21 d of osteogenic induction. Analysis of the expression levels of osteogenic markers suggested that SRE may promote osteogenic differentiation by acting at the early stage of differentiation rather than at the late stage of differentiation. These results indicate that SRE activates ER and induces osteoblast differentiation by activating Runx2 and Osx through the BMP/Smad pathway, suggesting that SRE may be useful for the prevention and treatment of postmenopausal osteoporosis.

Hydroxychloroquine Promotes Bcl-xL Inhibition-induced Apoptosis in BxPC-3 Human Pancreatic Cancer Cells

BACKGROUND/AIM

Anti-apoptotic proteins, including Bcl-2 and Bcl-xL, hinder cancer treatment, and several drugs targeting these molecules have been developed. One is ABT-263 (navitoclax), which targets Bcl-2, Bcl-xL, and Bcl-w. On the other hand, hydroxychloroquine (HCQ) has been used as a drug for malaria infection and autoimmune disease. HCQ can exert a similar effect as chloroquine with fewer adverse events. In addition, HCQ exerts antitumor activity. In the present study, the effects of HCQ on ABT-263-induced antitumor activities were examined using three human pancreatic cancer cell lines (PANC-1, MiaPaCa-2, and BxPC-3).

MATERIALS AND METHODS

In vitro effects of HCQ and ABT-263 were examined by cell viability, colony-forming assays, and flow cytometry. Protein expression was determined by immunoblotting. In vivo effects of HCQ and ABT-263 were examined by a xenograft mice model.

RESULTS

Combined treatment with HCQ and ABT-263 synergistically decreased the viability of only BxPC-3 cells. This synergistic effect was not observed when HCQ was combined with ABT-199, an inhibitor specific to Bcl-2. The combination of HCQ and ABT-263 induced caspase-dependent apoptosis. Protein expression of Bcl-xL was more highly expressed in BxPC-3 cells than in the other two cell lines, and the combination of HCQ with a Bcl-xL inhibitor or siRNA-mediated knockdown of Bcl-xL induced apoptosis in BxPC-3 cells. Combination therapy with HCQ and ABT 737, an ABT-263 analogue, suppressed the in vivo growth of BxPC-3 with transient body-weight loss.

CONCLUSION

HCQ effectively promotes Bcl-xL inhibition-induced apoptosis in BxPC-3 human pancreatic cancer cells.

Protective role of cytoplasmic p21Cip1/Waf1 in apoptosis of CDK4/6 inhibitor-induced senescence in breast cancer cells

Inhibition of CDK4/6 slows the cell cycle and induces senescence in breast cancer cells. However, senescent cancer cells promote invasion and metastasis. Several drugs reportedly target senescent cells, including ABT‐263 (navitoclax). We examined the effects of the CDK4/6 inhibitor abemaciclib and ABT‐263 on two human breast cancer cell lines. The abemaciclib and ABT‐263 combination additively decreased the viability of MDA‐MB‐231 cells, but not MCF‐7 cells. Also, the combination therapy‐induced caspase‐dependent apoptosis in MDA‐MB‐231 cells. Combination therapy with abemaciclib and ABT‐737, an ABT‐263 analog, significantly suppressed the in vivo growth of MDA‐MB‐231 with transient body‐weight loss. Given that p16^Ink4a and p21^Cip1/Waf1 are key factors in senescence and that both cell lines were negative for p16, the role of p21 in apoptosis of treated breast cancer cells was investigated. Although abemaciclib increased the cytoplasmic p21 level in both cell lines as a hallmark of senescence, the abemaciclib and ABT‐263 combination decreased it only in MDA‐MB‐231 cells. This decrease of p21 expression was relieved by caspase inhibition, and p21 was colocalized with caspase‐3 in the cytoplasm of MDA‐MB‐231 cells. Alternatively, small interfering RNA‐mediated knockdown of p21 rendered caspase‐3‐negative MCF‐7 cells susceptible to abemaciclib and ABT‐263, as well as TNF‐related apoptosis‐inducing ligand. Furthermore, a clinical database analysis showed that p21^high breast cancer patients had a poorer prognosis compared to p21^low patients. These results suggest that cytoplasmic p21 plays a protective role in apoptosis of CDK4/6 inhibitor‐induced senescent breast cancer cells.

Local injection of CCL19-expressing mesenchymal stem cells augments the therapeutic efficacy of anti-PD-L1 antibody by promoting infiltration of immune cells

Background

Mesenchymal stem/stromal cells (MSC) accumulate and reside in tumor sites.

Methods

Taking advantage of this feature in anticancer therapy, immortalized murine MSC (iMSC) were genetically altered to produce chemokine (C-C motif) ligand 19 (iMSC/CCL19), which attracts dendritic cells (DC) and T lymphocytes. Thereafter, iMSC/CCL19 were examined for their therapeutic efficacy using a syngeneic CT26 colon carcinoma cell line.

Results

Co-injection of iMSC/CCL19 into mice significantly suppressed the in vivo growth of CT26 cells compared with that of CCL19-expressing immortalized fibroblasts (iFib/CCL19). This anticancer effect was not observed when injected in CT26-bearing nude mice. Co-injected iMSC/CCL19 survived longer than iFib/CCL19 in the tumor sites. In a therapeutic model, local injection of iMSC/CCL19 suppressed the tumor growth, and increased IFN (interferon)-γ⁺ CD8⁺ T cells and CCR7⁺ DC infiltration in tumor site was observed when treated with iMSC/CCL19, but not with iMSC. This antitumor effect was completely negated by depletion of CD4⁺ cells and partially negated by depletion of CD8⁺ cells. Furthermore, the antitumor effects induced by local injection of iMSC/CCL19 were augmented by additional therapy with anti-programmed death (PD)-ligand 1 (PD-L1) antibody, but not with anti-PD-1 antibody. This combination therapy cured most of the tumors in CT26-bearing mice.

Conclusion

These results suggest that local therapy with iMSC/CCL19 can suppress tumor growth via effective recruitment of CCR7⁺ DC into tumor sites and increase IFN-γ⁺ CD8⁺ T cells, and that combination with anti-PD-L1 antibody therapy can be a powerful anticancer therapy.

T-cell responses and combined immunotherapy against human carbonic anhydrase 9-expressing mouse renal cell carcinoma

Renal cell carcinoma (RCC) is known to respond to immune checkpoint blockade (ICB) therapy, whereas there has been limited analysis of T-cell responses to RCC. In this study, we utilized human carbonic anhydrase 9 (hCA9) as a model neoantigen of mouse RENCA RCC. hCA9-expressing RENCA RCC (RENCA/hCA9) cells were rejected in young mice but grew in aged mice. CD8⁺ T cells were the primary effector cells involved in rejection in young mice, whereas CD4⁺ T cells participated at the early stage. Screening of a panel of hCA9-derived peptides revealed that mouse CD8⁺ T cells responded to hCA9_288-296 peptide. Mouse CD4⁺ T cells responded to lysates of RENCA/hCA9, but not RENCA cells, and showed reactivity to hCA9 _276-290, which shares three amino acids with hCA9 _288-296 peptide. Immunohistochemistry analysis revealed that few T cells infiltrated RENCA/hCA9 tissues in aged mice. ICB therapy of anti-PD-1/anti-CTLA-4 antibodies promoted T-cell infiltration into tumor tissues, whereas no definite antitumor effect was observed. However, additional combination with cyclophosphamide or axitinib, a vascular endothelial growth factor receptor inhibitor, induced complete regression in half of the RENCA/hCA9-bearing aged mice with increased expression of PD-L1 in tumor tissues. These results indicate that hCA9 can be a useful model neoantigen to investigate antitumor T-cell responses in mice with RCC, and that RENCA/hCA9 in aged mice can serve as a non-inflamed 'cold' tumor model facilitating the development of effective combined immunotherapies for RCC.

Immunogenic chemotherapy in two mouse colon cancer models

Aside from the induction of cell death, some anticancer chemotherapeutic drugs can modulate antitumor immune responses. In this study, we examined the anticancer effects of 5‐fluorouracil (5‐FU) and oxaliplatin (L‐OHP), which are standard chemotherapeutic drugs for colon cancer, combined with cyclophosphamide (CP) in two mouse colon cancer models (CT26 and MC38 colon adenocarcinoma models). In the CT26 model, two injections of 5‐FU/L‐OHP and CP significantly suppressed the growth of subcutaneously established CT26 tumors compared with either 5‐FU/L‐OHP or CP, without a significant loss of body weight. The anticancer effect was weakened in nude mice. Cured mice acquired protective immunity against CT26, and CT26‐specific cytotoxic T cells (CTLs) were induced from their spleen cells. Analysis of tumor‐infiltrating immune cells revealed that 5‐FU/L‐OHP treatment with or without CP increased the proportion of CD8⁺ T cells at tumor sites. The 5‐FU/L‐OHP treatment decreased the proportion of granulocytic myeloid‐derived suppressor cells (MDSCs) and increased monocytic MDSCs in tumor sites, whereas the addition of CP treatment reversed these changes. In the MC38 model, although significant anticancer effects of the triple combination therapy were seen, additional treatment with anti‐PD‐1 antibody increased the number of cured mice. These mice exhibited protective immunity against MC38, and MC38‐specific CTLs were generated from their spleen cells. Together, these results indicate that the antitumor effects of the combination of 5‐FU/L‐OHP and CP mainly depend on host T cells; moreover, the therapeutic efficacy can be effectively boosted by immune checkpoint blockade.

Supplementation of l-arginine boosts the therapeutic efficacy of anticancer chemoimmunotherapy

Myeloid‐derived suppressor cells (MDSCs) play a crucial role in immunosuppression in tumor‐bearing hosts. MDSCs express arginase‐I and indoleamine 2,3‐dioxygenase; they suppress T‐cell function by reducing the levels of l‐arginine and l‐tryptophan, respectively. We examined the anticancer effects of supplementation of these amino acids in CT26 colon carcinoma‐bearing mice. Oral supplementation of l‐arginine or l‐tryptophan (30 mg/mouse) did not affect tumor growth, whereas oral supplementation of d‐arginine was lethal. Supplementation of l‐arginine showed a tendency to augment the efficacy of cyclophosphamide (CP). CP reduced the proportions of granulocytic MDSCs and increased the proportions of monocytic MDSCs in the spleen and tumor tissues of CT26‐bearing mice. l‐Arginine supplementation alone did not affect the MDSC subsets. CP treatment tended to reduce the plasma levels of l‐arginine in CT26‐bearing mice and significantly increased the number of tumor‐infiltrating CD8⁺ T cells. In addition, l‐arginine supplementation significantly increased the proportions of tumor peptide‐specific CD8⁺ T cells in draining lymph nodes. Importantly, additional supplementation of l‐arginine significantly increased the number of cured mice that were treated with CP and anti‐PD‐1 antibody. Totally, l‐arginine supplementation shows promise for boosting the therapeutic efficacy of chemoimmunotherapy.

Pemetrexed sensitizes human lung cancer cells to cytotoxic immune cells

Pemetrexed (PEM) is a useful drug that can be combined with immune checkpoint blockade therapy for treatment of patients with advanced non–small‐cell lung cancer (NSCLC). However, its effects on anti–cancer immunity, especially the sensitivity of NSCLC cells to cytotoxic immune cells, have not been fully investigated. In this study, we examined the effects of PEM on the sensitivity of human NSCLC cells to two different types of cytotoxic immune cells. Pre‐treatment with PEM increased the sensitivity of two NSCLC cell lines, PC9 and A549, to activated T cells and natural killer (NK) cells, and decreased the expression of anti–apoptotic proteins, including XIAP and Mcl‐1. In addition, PEM treatment increased the cell surface expression of programmed death‐ligand 1 (PD‐L1) on PC9 cells. PEM‐induced upregulation of PD‐L1 on PC9 cells was at least partially ascribed to activation of ERK and the NFκB pathway. In contrast, PEM treatment increased the expression of UL16‐binding proteins (ULBP), ligands for the NKG2D NK receptor, on PC9 and A549 cells, as well as the induction of senescence. Although the addition of anti–programmed cell death 1 antibody showed no effect on the sensitivity of PEM‐treated PC9 and A549 cells to activated T cells, that of anti–NKG2D antibody decreased the enhanced sensitivity of PEM‐treated A549 cells to NK cells. These results indicate that PEM can effectively sensitize human NSCLC cells to cytotoxic immune cells while modulating the expression of immune‐regulatory molecules.

Different sensitivities of senescent breast cancer cells to immune cell-mediated cytotoxicity

Senescence is a state of growth arrest induced not only in normal cells but also in cancer cells by aging or stress, which triggers DNA damage. Despite growth suppression, senescent cancer cells promote tumor formation and recurrence by producing cytokines and growth factors; this state is designated as the senescence‐associated secretory phenotype. In this study, we examined the susceptibility of senescent human breast cancer cells to immune cell‐mediated cytotoxicity. Doxorubicin (DXR) treatment induced senescence in 2 human breast cancer cell lines, MDA‐MB‐231 and BT‐549, with the induction of γH2AX expression and increased expression of p21 or p16. Treatment with DXR also induced the expression of senescence‐associated β‐galactosidase and promoted the production of pro‐inflammatory cytokines. Importantly, DXR‐treated senescent MDA‐MB‐231 cells showed increased sensitivity to 2 types of immune cell‐mediated cytotoxicity: cytotoxicity of activated CD4⁺ T cells and Ab‐dependent cellular cytotoxicity by natural killer cells. This increased sensitivity to cytotoxicity was partially dependent on tumor necrosis factor‐related apoptosis‐inducing ligand and perforin, respectively. This increased sensitivity was not observed following treatment with the senescence‐inducing cyclin‐dependent kinase‐4/6 inhibitor, abemaciclib. In addition, treatment with DXR, but not abemaciclib, decreased the expression of antiapoptotic proteins in cancer cells. These results indicated that DXR and abemaciclib induced senescence in breast cancer cells, but that they differed in their sensitivity to immune cell‐mediated cytotoxicity. These findings could provide an indication for combining anticancer immunotherapy with chemotherapeutic drugs or molecular targeting drugs.

Abstract P4-06-28: Doxorubicin induces cellular senescence in human breast cancer cells and sensitizes them to cytotoxic T-lymphocytes

[Background]“Cellular senescence” is a state in which cells undergo irreversible cell cycle arrest in response to various cellular stresses. Senescence is induced in not only normal cells but also cancer cells when anti-cancer agents trigger DNA damage. Recent studies have revealed additional feature of senescent cells: increased secretion of various secretory proteins, such as inflammatory cytokines, chemokines, growth factors, and MMPs. This newly recognized senescent phenotype, termed senescence-associated secretory phenotype (SASP), reportedly contribute to tumor recurrence and promotion. Alternatively, senescent cancer cells could be good targets in anti-cancer immunotherapy because they are cell cycle-arrested.

[Objective]In this study, we determined whether ”cellular senescence” could be induced by a chemotherapeutic drug doxorubicin (DXR) and whether senescent cancer cells might increase their susceptibility to cytotoxic T-lymphocytes using human breast cancer cells.

[Methods and Results]A triple-negative (negative for ER, PR, and HER2) human breast cancer cell line (MDA-MB-231) was used. This cell line was treated with DXR for 2 days and examined for their appearance microscopically. The DXR treatment (500 nM) decreased their proliferating ability and increased their cell size. Colony formation assay revealed that cancer cells significantly decreased the number of colonies even with lower doses (3 nM) of DXR. In immunoblot assay, the DXR treatment increased the protein expression of p21, which inhibits cell cycle. In a flow cytometric assay after staining with SPIDER-β-gal, the DXR treatment (500 nM) increased the expression of β-gal in MDA-MB-231 cells. The induction of SA-β-gal in DXR-treated cancer cells were also confirmed by confocal imaging. In addition, the DXR treatment (500 nM) for 2 days beforehand increased their subsequent ability to produce IL-6 and IL-8. Although the DXR treatment (500 nM) decreased the expression of epidermal growth factor receptor (EGFR) on cancer cells, this treatment sensitized them to anti-EGFR chimeric antigen receptor (CAR) T-lymphocytes in apoptosis assay.

[Conclusion]These results suggest that a chemotherapeutic drug DXR can render MDA-MB-231 cells to be senescent and increase their sensitivity to antigen-specific cytotoxic T-lymphocytes. These findings may provide a rationale of combination of chemotherapy and T cell-based anti-cancer immunotherapy.

Citation Format: Inao T, Iida Y, Kotani H, Harada M. Doxorubicin induces cellular senescence in human breast cancer cells and sensitizes them to cytotoxic T-lymphocytes [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 P4-06-28.

Bcl-2 inhibition sensitizes triple-negative human breast cancer cells to doxorubicin

Breast cancers can be divided into several types. Because triple-negative breast cancer (TNBC) is the most refractory to current anti-cancer therapies, efficient treatment has been urgently required. Members of the Bcl-2 family play pro- and anti-apoptotic roles in mitochondria-mediated apoptosis. Some Bcl-2 family members are expressed in breast cancer and influence the response to anti-cancer therapies. In this study, we investigated whether Bcl-2 inhibition could sensitize TNBC cells to the genotoxic drug doxorubicin (DR). Treatment with a combination of the Bcl-2 inhibitor ABT-199 and DR synergistically decreased the viability of the TNBC cell lines MDA-MB-231 and BT-549. In an apoptosis assay, the combination treatment resulted in only a marginal effect in BT-549 cells, whereas drastic apoptosis was induced in MDA-MB-231 cells treated with both ABT-199 and DR. Both caspase-8 and -9 were involved in the combination treatment-induced apoptosis. Short interfering RNA-mediated knockdown of Bcl-2 increased the sensitivity of both cell lines to DR. The combination treatment also significantly decreased the colony-forming ability of the TNBC cell lines. In a xenograft mouse model, oral administration of ABT-199 augmented the DR-induced antitumor effect on subcutaneously established MDA-MB-231 cells. These results indicate that the combination of DR with Bcl-2 inhibitors, including ABT-199, may be a promising treatment modality for TNBC patients.

Abstract P2-01-09: Circulating tumor cells (CTCs) in the venous drainage of the breast in patients with primary breast cancer

Background:

CTCs are shed from tumors and circulate in the peripheral blood after passing through the drainage vein. Axillary lymph node dissection (ALND) provides access to the lateral thoracic vein which flows directly into the axillary vein. In this preliminary study, we evaluated the feasibility of detecting CTCs in the peripheral blood and in the lateral thoracic venous blood for breast cancer patients who underwent ALND.

Methods:

From June 2016 to March 2017, breast cancer patients who underwent ALND in our institute were eligible for this study. A peripheral blood sample,10ml, was drawn just before the surgery or one day before the surgery. A lateral thoracic venous blood sample was taken from the resected breast just after resection. A blood sample of 0.2ml or more was necessary for CTC isolation. The CTCs in the peripheral blood before surgery (periCTC) and in the blood from the lateral thoracic vein of the resected breast (ltvCTC) were quantitatively examined by using a size-selective CTC isolation platform.

Results:

A total of 21 patients with median age 51 years (37-75) were enrolled to the study. Of the 21 patients, 38% were premenopausal, 52% had neoadjuvant chemotherapy. Fifty-seven percent were ER and/or PgR positive, 24% were HER2 positive. Fifty-seven percent were stage II disease and 43% were stage III. In 3 patients, we couldn't obtain sufficient blood samples from the lateral thoracic vein. Of the remaining 18 patients, we were able to obtain the median 0.5ml (0.2-2.0) blood samples from the lateral thoracic vein. CTCs were detected in peripheral blood in 15 patients (71%) and median periCTC count was 1 CTC/10ml (0-39). In lateral thoracic venous blood, CTCs were detected in all patients who had sufficient blood samples and the median ltv CTC count was 35.5 CTC/ml (2.5-370). In 5 of 6 patients whom CTCs in peripheral blood samples were not detected, CTCs could be detected in the blood samples from lateral thoracic vein.

Conclusion:

CTCs can be detected in the peripheral blood and in the blood from lateral thoracic vein in patients with localized breast cancer, and can be detected at a higher rate and at a higher concentration in the blood from lateral thoracic vein than in peripheral blood.

Citation Format: Hattori M, Nakanishi H, Yoshimura A, Adachi Y, Iwase M, Gondo N, Kotani H, Sawaki M, Yatabe Y, Iwata H. Circulating tumor cells (CTCs) in the venous drainage of the breast in patients with primary 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 P2-01-09.

Abstract P2-12-13: Withdrawn

This abstract was withdrawn by the authors.

Abstract P5-09-07: Impact of germinalcenter-associated nuclear protein polymorphisms on breast cancer risk and prognosis in a Japanese population

Background: Germinal center-associated nuclear protein (GANP) is a phosphoprotein which is involved in mRNA export and the regulation of DNA recombination. We have previously demonstrated that deficiency of GANP led to spontaneous development of mammary gland tumors in a mouse model. In addition, we found that decreased GANP expression in human breast cancer tissue was an independent prognostic factor. Here, we conducted a case-control study and a retrospective cohort study to investigate whether single nucleotide polymorphisms (SNPs) of GANP are associated with sporadic breast cancer risk and prognosis in a Japanese population.

Subjects and Methods: Six hundred-ninety-four breast cancer cases and 1,376 age- and menopausal status-matched controls were selected within the framework of the Hospital-based Epidemiologic Research Program at Aichi Cancer Center. Cases and controls were genotyped using an Infinium iSelect custom array (iCOGS, Illumina Inc., San Diego, CA, USA). We assessed 13 SNPs at the GANP locus, 2 SNPs (rs2839178 and rs11702450) were selected for further analysis by considering linkage disequilibrium. Conditional logistic regression methods were used to estimate odds ratios (ORs) and 95% confidence intervals. In addition, the survival impact of the two SNPs was retrospectively analyzed using the 694 breast cancer cases. To evaluate the effect of SNPs on overall survival (OS) and disease-free survival (DFS), multivariate Cox proportional hazards modeling was applied.

Results: Compared to the AA genotype of rs2839178, the GG genotype showed statistically significant associations with breast cancer risk (OR: 0.48, 95%CI:0.30–0.76, P = 0.002). In prognostic analysis, compared to those with the genotype AA at rs2839178, patients with AG or GG showed longer DFS (HR: 0.71, 95%CI: 0.49–1.04 and 0.42, 0.13–1.42, respectively, P for trend = 0.04). The GG genotype of rs2839178 also showed a positive tendency for longer OS although it was not statistically significant (HR: 0.69, 95%CI: 0.44–1.08, P = 0.11). We did not find that rs11702450 was associated with either breast cancer risk or prognosis.

Conclusion: This is the first study to investigate the association between GANP SNPs and breast cancer risk and prognosis. The direction of association with DFS was consistent with that of susceptibility. These results demonstrate that GANP SNPs presumably prevent the occurrence and malignant advancement of sporadic breast cancers.

Citation Format: Kotani H, Ito H, Kuwahara K, Kuzushima K, Iwata H, Tsunoda N, Nagino M, Tanaka H, Matsuo K. Impact of germinalcenter-associated nuclear protein polymorphisms on breast cancer risk and prognosis in a Japanese population [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 P5-09-07.

Rexinoids isolated from Sophora tonkinensis with a gene expression profile distinct from the synthetic rexinoid bexarotene

The retinoid X receptor (RXR) plays a critical role in transcriptional regulation via formation of an RXR homodimer or heterodimers with partner nuclear receptors. Despite the numerous beneficial effects, only a limited number of naturally occurring RXR agonists are known. In this report, two prenylated flavanones (1 and 2) isolated from Sophora tonkinensis were identified as new rexinoids that preferentially activated RXRs, relative to the retinoic acid receptor. The activities of 1 and 2 were the most potent among naturally occurring rexinoids, yet 2 orders of magnitude lower than the synthetic rexinoid bexarotene. Compounds 1 and 2 activated particular RXR heterodimers in a manner similar to bexarotene. A microarray assay followed by quantitative real-time polymerase chain reaction analyses on RNAs isolated from C2C12 myotubes treated with 1 or 2 demonstrated that they significantly increased mRNA levels of lipoprotein lipase, angiopoietin-like protein 4, and heme oxygenase-1. In contrast, bexarotene preferentially potentiated transcription of genes involved in lipogenesis and lipid metabolism such as sterol regulatory element-binding protein-1, fatty acid synthase, and apolipoprotein D by a liver X receptor agonist. In this study, we have demonstrated that two newly identified naturally occurring rexinoids, 1 and 2, possess properties different from bexarotene.

Abstract P5-14-02: Postmastectomy radiation improves loco-regional control for patients with advanced breast cancer treated with neoadjuvant chemotherapy

Purpose

The value of postmastectomy radiation (PMRT) with adjuvant chemotherapy has been established, but the role of PMRT after neoadjuvant chemotherapy remains unclear.

The aim of this study was to evaluate the efficacy of radiation in patients treated with neoadjuvant chemotherapy and mastectomy, and to determine which subsets of patients benefit from PMRT.

Patients and Methods

From 2003 to 2008, 94 patients were treated with neoadjuvant chemotherapy and mastectomy. The median number of lymph nodes removed was 20. 90 patients received anthracycline-based (anthracycline alone: 5, anthracycline followed by taxane: 85) chemotherapy and 4 patients received taxane alone. 82.6 percent (19/23) of the patients with HER2 positive cancer received trastuzumab and 91.3 percent (63/69) of the patients with hormone receptor positive cancer received hormone therapy. In this study, pathological complete response (pCR) was defined as absence of invasive tumor in the breast.

We compared the outcomes of 55 patients who received radiation (PMRT group) from 39 patinets who did not receive radiation (non-PMRT group).

The 5 years rate of loco-regional recurrence (LRR) was calculated according to the Kaplan-Meier method, and comparisons between the two groups were made using the log-rank test.

Results

Median follow-up time was 61.8 months. The breast pCR rate was 17.0% (16/94). 14 patients developed LRR as first events (local: 8, regional: 4, local and regional: 2). There were no differences between the two groups with respect to age, use of trastzumab, use of hormone therapy, pathological tumor size, number of dissected axillary nodes, percentage of hormone receptor positive tumors, or HER2 positive tumors.

The 5-years rate of LRR for the PMRT group and the non-PMRT group were 12.8% and 27.0% respectively. (p = 0.144) In the patients with positive lymph nodes after neoadjuvant chemotherapy, the PMRT group had significantly lower LRR risk than the non-PMRT group (5-yaers rate: 11.9% vs 37.5%, p = 0.039). But in the patients with negative lymph node, there were no significant difference between the PMRT group and the non-PMRT group. For hormone receptor positive and HER2 negative subtype, a significantly improved LRR risk found after PMRT (5-yaers rate: 5.9% vs 26.1%, p = 0.048). No significant difference in HER2 positive subtype and triple negative subtype were observed between two groups. In the patients who did not achieve breast pCR, the PMRT group had significantly lower LRR risk than the non-PMRT group (5-yaers rate: 9.0% vs 30.6%, p = 0.037). The 5-years rate of lymphedema was no significant difference between the two groups (p = 0.787).

Conclusion

After neoadjuvant chemotherapy and mastectomy, PMRT was found to benefit local control for the patients with positive lymph nodes, the patients with hormone receptor positive and HER2 negative cancer, and the patients who did not achieve breast pCR.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-02.

TRAF6 is essential for maintenance of regulatory T cells that suppress Th2 type autoimmunity

Regulatory T cells (Tregs) maintain immune homeostasis by limiting inflammatory responses. TRAF6 plays a key role in the regulation of innate and adaptive immunity by mediating signals from various receptors including the T-cell receptor (TCR). T cell-specific deletion of TRAF6 has been shown to induce multiorgan inflammatory disease, but the role of TRAF6 in Tregs remains to be investigated. Here, we generated Treg-specific TRAF6-deficient mice using Foxp3-Cre and TRAF6-flox mice. Treg-specific TRAF6-deficient (cKO) mice developed allergic skin diseases, arthritis, lymphadenopathy and hyper IgE phenotypes. Although TRAF6-deficient Tregs possess similar in vitro suppression activity compared to wild-type Tregs, TRAF6-deficient Tregs did not suppress colitis in lymphopenic mice very efficiently due to reduced number of Foxp3-positive cells. In addition, the fraction of TRAF6-deficient Tregs was reduced compared with wild-type Tregs in female cKO mice without inflammation. Moreover, adoptive transfer of Foxp3 ⁺ Tregs into Rag2^-/- mice revealed that TRAF6-deficient Tregs converted into Foxp3^- cells more rapidly than WT Tregs under lymphopenic conditions. Fate-mapping analysis also revealed that conversion of Tregs from Foxp3⁺ to Foxp3^- (exFoxp3 cells) was accelerated in TRAF6-deficient Tregs. These data indicate that TRAF6 in Tregs plays important roles in the maintenance of Foxp3 in Tregs and in the suppression of pathogenic Th2 type conversion of Tregs.

Smad2/3 and IRF4 play a cooperative role in IL-9-producing T cell induction

IL-9 is a pleiotropic cytokine that can regulate autoimmune and allergic responses. Th9 cells can develop from naive T cells or Th2 cells through stimulation by TGF-β in vitro. In this study, we demonstrated that Smad2 and Smad3 are necessary for IL-9 production from T cells in an OVA-induced asthma model using T cell-specific Smad2- and Smad3-deficient mice. Smad2 and Smad3 were also redundantly essential for TGF-β signaling to induce histone modifications for Il9 transcription. Although Smad2/3 was recruited to the Il9 promoter by TGF-β stimulation, they are not sufficient to activate the Il9 promoter. By the screening the transcription factors, we found that IFN regulatory factor 4 (IRF4) was essential for the Smad2/3-mediated Il9 promoter activation. In addition, Smad2/3 physically interacted with IRF4, and Smad2/3 did not bind to the Il9 promoter and could not induce Th9 in IRF4-deficient T cells. Similarly, IRF4 could not stimulate Il9 transcription in the absence of Smad2/3, and TGF-β enhanced IRF4 recruitment to the Il9 promoter in a Smad2/3-dependent manner. We propose that Smad2/3 and IRF4 cooperatively transactivate the Il9 promoter and play an important role in regulating allergic immune responses by inducing Th9 cells.

Increased plasma LIGHT levels in patients with atopic dermatitis

LIGHT [the name of which is derived from 'homologous to lymphotoxins, exhibits inducible expression, competes with herpes simplex virus glycoprotein D for herpes simplex virus entry mediator (HVEM), and expressed by T lymphocytes'], is a member of the tumour necrosis factor superfamily that is involved in various inflammatory diseases. We aimed to estimate the relevance of plasma LIGHT levels as a biomarker for atopic dermatitis (AD). In order to understand the putative role of LIGHT in AD pathogenesis, we also investigate the effects of LIGHT on a monocytic cell line, human acute monocytic leukaemia cell line (THP-1). We examined plasma LIGHT levels, total serum IgE, serum value of CCL17 and peripheral blood eosinophil counts in patients with AD and healthy subjects. The effects of LIGHT on activation and apoptosis in THP-1 cells were also investigated. The plasma concentrations of LIGHT in AD patients were significantly higher than those in healthy individuals and the concentrations decreased as the symptoms were improved by treatment. The LIGHT plasma concentrations correlated with IgE levels and the Severity Scoring of AD (SCORAD) index. In addition, LIGHT stimulation increased expression of CD86 and induced production of interleukin-1β in THP-1 cells. Apoptosis was inhibited, the Bcl-2 level increased and the caspase-3 level decreased in THP-1 cells stimulated with LIGHT, compared to unstimulated control cells. These results suggest that plasma LIGHT levels may be one of the promising biomarkers for AD.

Influence of leukotriene pathway polymorphisms on clinical responses to montelukast in Japanese patients with asthma

WHAT IS KNOWN AND OBJECTIVE

Montelukast, a cysteinyl leukotriene receptor 1 antagonist, is safe and efficacious in patients with asthma. The mechanisms underlying the significant interpatient variability in response to montelukast are not clear but are believed to be, in part, because of genetic variability.

METHODS

To examine the associations between polymorphisms in candidate genes in the leukotriene pathway and outcomes in patients with asthma on montelukast for 4-8 weeks, we evaluated the changes in peak expiratory flow (PEF), forced expiratory volume in 1 s (FEV(1·0) ) and patients' subjective symptom before and after montelukast treatment. DNA was collected from 252 Japanese participants.

RESULTS AND DISCUSSION

Two single-nucleotide polymorphisms (SNPs) in the ALOX5 (rs2115819) and LTA4H (rs2660845) genes were successfully typed. There was no difference between members of the general population (n = 200) and patients (n = 52) in each genotype frequency. Significant associations were found between SNP genotypes in the LTA4H gene and changes in PEF and FEV(1·0) . The PEF and FEV(1·0) responses to montelukast in the A/A genotypes (n = 4) for the LTA4H SNP were significantly higher than those in the G allele carriers (A/G+G/G) (n = 17).

WHAT IS NEW AND CONCLUSION

Despite the small sample size, our results suggest that genetic variation in leukotriene pathway candidate genes contributes to variability in clinical responses to montelukast in Japanese patients with asthma.

Dose-dependent modulatory effects of insulin on glucose-induced endothelial senescence in vitro and in vivo: a relationship between telomeres and nitric oxide

The elderly are prone to postprandial hyperglycemia that increases their cardiovascular risk. Although insulin therapy is necessary to treat diabetes, high plasma concentrations of insulin may cause the development of atherosclerosis and accelerate endothelial senescence. We assumed that high glucose causes stress-induced premature senescence and replicative senescence and examined the regulatory role of insulin in endothelial senescence and functions under different glucose conditions. Exposure of human endothelial cells to high glucose (22 mM) for 3 days increased senescence-associated-β-galactosidase activity, a senescence marker, and decreased telomerase activity, a replicative senescence marker. Physiological concentrations of insulin preserved telomere length and delayed endothelial senescence under high-glucose conditions. The effect of insulin under high-glucose conditions was associated with reduced reactive oxygen species and increased nitric oxide (NO). Small interfering RNA targeting endothelial NO synthase reduced the antisenescence effects of insulin. Physiological concentrations of insulin also reversed high glucose-induced increases in p53 and vascular cell adhesion molecule-1 and decreases in senescence marker protein-30. On the other hand, when insulin was given at any concentrations under normal glucose or at high concentrations under high glucose, its ability to promote cellular senescence was unrelated to endothelial NO. Finally, streptozotocin-induced diabetes showed more senescent cells in the aortic endothelium of aged rats compared with age-matched control and insulin-treated animals. Conclusively, the regulatory effects of insulin on endothelial senescence were modulated by the glucose environment. These data may help explain insulin's complicated roles in atherosclerosis in the elderly.

Gene expression-based pharmacodynamic biomarkers: the beginning of a new era in biomarker-driven anti-tumor drug development

Pharmacodynamic (PD) biomarkers play a pivotal role in anti-tumor drug development as a biochemical measurement to estimate the level of drug interaction with the target, or to assess the downstream impact of its interaction with the target. Although immunohistochemistry (IHC)-based protein biomarkers have been conventionally used as PD biomarkers, gene expression-based PD biomarkers have recently emerged as quantitative biomarkers. This review introduces examples of gene expression-based mRNA biomarkers that have been validated in preclinical or clinical studies of several anti-tumor agents including HDAC, mTOR, and B-RAF inhibitors. The measurement of PD biomarker levels in tumors has proven to be ideal; however, in clinical studies, easily accessible surrogate tissues have been used for analysis. In the present review, we also discuss the advantages and disadvantages in using surrogate tissues, such as peripheral blood mononuclear cells (PBMCs), skin tissue, and circulating tumor cells, in the assessment of PD biomarkers. PD biomarkers are generally classified into two categories: 1) target engagement biomarkers and 2) early efficacy biomarkers. This classification depends on their respective distance from target intervention. The strategies used to identify and distinguish between these two types of PD biomarkers via expression profiling are also discussed. Finally, we propose two novel approaches for PD marker identification. One approach utilizes mRNA expression profiling of tumors prior to drug treatment rather than post-treatment samples. The second method involves the application of microRNA expression profiles to determine PD effects. In conclusion, the recent advances in mRNA and microRNA profiling and the identification of gene expression-based PD biomarkers may aid investigators to drive drug development through the establishment of quantitative PD effects.

Identification of a naturally occurring rexinoid, honokiol, that activates the retinoid X receptor

Screening of a total of 86 crude drugs for retinoid X receptor (RXR) ligands demonstrated that the methanol extract of the bark of Magnolia obovata markedly activated the transcriptional activity of RXRalpha in luciferase reporter assays. Thereafter, honokiol (1) was isolated as a constituent able to activate RXR selectively as a natural rexinoid, but not RARalpha. The activity of 1 was more potent than those of phytanic acid and docosahexaenoic acid, both of which are known to be natural RXR agonists. Honokiol (1) is capable of activating a RXR/LXR heterodimer, resulting in the induction of ATP-binding cassette transporter A1 mRNA and protein expression in RAW264.7 cells, as well as an increase in [(3)H]cholesterol efflux from peritoneal macrophages. These effects of 1 were enhanced synergistically in the presence of an LXR agonist, 22(R)-hydroxycholesterol. The results obtained demonstrate that 1, a newly identified natural rexinoid, regulates the functions of RXR/LXR heterodimer and abrogates foam cell formation by the induction of ABCA1 via activation of the RXR/LXR heterodimer.