Enhancement of PD-L1-attenuated CAR-T cell function through breast cancer-associated fibroblasts-derived IL-6 signaling via STAT3/AKT pathways.

BACKGROUND: Carcinoma-associated fibroblasts (CAFs) play a critical role in cancer progression and immune cell modulation. In this study, it was aimed to evaluate the roles of CAFs-derived IL-6 in doxorubicin (Dox) resistance and PD-L1-mediated chimeric antigenic receptor (CAR)-T cell resistance in breast cancer (BCA). METHODS: CAF conditioned-media (CM) were collected, and the IL-6 level was measured by ELISA. CAF-CM were treated in MDA-MB-231 and HCC70 TNBC cell lines and siIL-6 receptor (IL-6R) knocked down (KD) cells to determine the effect of CAF-derived IL-6 on Dox resistance by flow cytometry and on increased PD-L1 through STAT3, AKT and ERK1/2 pathways by Western blot analysis. After pre-treating with CM, the folate receptor alpha (FRα)-CAR T cell cytotoxicity was evaluated in 2D and 3D spheroid culture assays. RESULTS: The results showed a significant level of IL-6 in CAF-CM compared to that of normal fibroblasts (NFs). The CM with high IL-6 level significantly induced Dox resistance; and PD-L1 expression through STAT3 and AKT pathways in MDA-MB-231 and HCC70 cells. These induction effects were attenuated in siIL-6R KD cells. Moreover, the TNBC cell lines that were CM-treated with STAT3 and an AKT inhibitor had a reduced effect of IL-6 on PD-L1 expression. BCA cells with high IL-6 containing-CM treatment had resistance to cancer cell killing by FRα CAR-T cells compared to untreated cells. CONCLUSION: These results highlight CAF-derived IL-6 in the resistance of chemotherapy and T cell therapy. Using inhibitors of IL6-STAT3/AKT-PD-L1 axis may provide a potential benefit of Dox and CAR-T cell therapies in BCA patients.

Establishment and characterization of novel highly aggressive HER2­positive and triple­negative breast cancer cell lines.

Breast cancer cell lines are widely used as an in vitro system with which to study the mechanisms underlying biological and chemotherapeutic resistance. In the present study, two novel breast cancer cell lines designated as PC­B­142CA and PC­B­148CA were successfully established from HER2­positive and triple­negative (TN) breast cancer tissues. The cell lines were characterized by cytokeratin (CK), α­smooth muscle actin (α­SMA), fibroblast­activation protein (FAP) and programmed death­ligand 1 (PD­L1). Cell proliferation was assessed using a colony formation assay, an MTS assay, 3­dimensional (3­D) spheroid and 3­D organoid models. Wound healing and Transwell migration assays were used to explore the cell migration capability. The responses to doxorubicin (DOX) and paclitaxel (PTX) were evaluated by 3­D spheroids. The results showed that the PC­B­142CA and PC­B­148CA cell lines were α­SMA­negative, FAP­negative, CK­positive and PD­L1­positive. Both cell lines were adherent with the ability of 3­D­multicellular spheroid and organoid formations; invadopodia were found in the spheroids/organoids of only PC­B­148CA. PC­B­142CA had a faster proliferative but lower metastatic rate compared to PC­B­148CA. Compared to MDA­MB­231, a commercial TN breast cancer cell line, PC­B­148CA had a similar CD44+/CD24­ stemness property (96.90%), whereas only 8.75% were found in PC­B­142CA. The mutations of BRCA1/2, KIT, PIK3CA, SMAD4, and TP53 were found in PC­B­142CA cells related to the resistance of several drugs, whereas PC­B­148CA had mutated BRCA2, NRAS and TP53. In conclusion, PC­B­142CA can serve as a novel HER2­positive breast cancer cell line for drug resistance studies; while PC­B­148CA is a novel TN breast cancer cell line suitable for metastatic and stemness­related properties.

Crosstalk between Tumor-Infiltrating Immune Cells and Cancer-Associated Fibroblasts in Tumor Growth and Immunosuppression of Breast Cancer.

Signals from the tumor microenvironment (TME) have a profound influence on the maintenance and progression of cancers. Chronic inflammation and the infiltration of immune cells in breast cancer (BC) have been strongly associated with early carcinogenic events and a switch to a more immunosuppressive response. Cancer-associated fibroblasts (CAFs) are the most abundant stromal component and can modulate tumor progression according to their secretomes. The immune cells including tumor-infiltrating lymphocytes (TILs) (cytotoxic T cells (CTLs), regulatory T cells (Tregs), and helper T cell (Th)), monocyte-infiltrating cells (MICs), myeloid-derived suppressor cells (MDSCs), mast cells (MCs), and natural killer cells (NKs) play an important part in the immunological balance, fluctuating TME between protumoral and antitumoral responses. In this review article, we have summarized the impact of these immunological players together with CAF secreted substances in driving BC progression. We explain the crosstalk of CAFs and tumor-infiltrating immune cells suppressing antitumor response in BC, proposing these cellular entities as predictive markers of poor prognosis. CAF-tumor-infiltrating immune cell interaction is suggested as an alternative therapeutic strategy to regulate the immunosuppressive microenvironment in BC.

Interleukin­8 released by cancer­associated fibroblasts attenuates the autophagy and promotes the migration of ovarian cancer cells.

The tumor microenvironment composed of a mixture of stromal cells and their secretions has a marked impact on cancer progression. In particular, soluble factors and metabolites contribute to malignancy through the dysregulation of autophagy in cancer cells. The present study investigated the effects of ovarian cancer­associated fibroblasts (OVCAFs) with their secretory substances on the autophagy and migration of ovarian cancer cells. The conditioned­medium (CM) of OVCAFs isolated from fresh human ovarian cancer tissues was analyzed for the levels of 27 common cytokines/chemokines using a cytokine array. Autophagy in cancer cells was assessed by determining the expression of the vacuolar form of LC3 by western blot analysis and immunofluorescence. Cancer cell migration was assessed by Transwell migration assay. Interleukin (IL)­8 was found to be the most highly upregulated cytokine among the cytokines/chemokines found in the OVCAF­CM. The role of IL­8 in ovarian cancer cell migration and its mechanistic link with autophagy was investigated. Recombinant human IL­8 (rhIL­8) stimulated the migration of SKOV3 and Kuramochi ovarian cancer cells, and concurrently downregulated basal autophagy, in concentration­dependent manner. Compared to the CM of control counterpart normal fibroblasts isolated from benign ovaries (OVNF­CM), the CM from 3 OVCAF isolates (namely, OVCAF­9, ­20 and ­43) exerted effects similar to rhIL­8 on both cancer cell lines. The pharmacological induction of autophagy with rapamycin or metformin attenuated the pro­migratory effects of IL­8. Neutralizing anti­IL­8 antibody counteracted the inhibitory effect of OVCAF­CM on basal autophagy. On the whole, the present study highlights the involvement of IL­8 released by CAFs in the ovarian tumor microenvironment in promoting cancer cell migration through the suppression of autophagy.

Breast cancer stem cell RNA-pulsed dendritic cells enhance tumor cell killing by effector T cells.

Cancer stem cells (CSCs) underpin the resistance of breast cancer (BC) cells to therapy. Dendritic cell (DC)-based treatment is efficacious and safe, but the efficiency of this technique for targeting CSCs in BC treatment requires further investigation. The present study aimed to investigate the ability of DCs pulsed with breast CSC antigens to activate effector lymphocytes for killing BC cells. CD44+/CD24- CSCs were isolated from BCA55-121, an in-house patient-derived BC cell line, and acquisition of stemness properties was confirmed by upregulated expression of OCT4A and a superior proliferative capacity in colony formation assays compared with whole population of BCA55-121 (BCA55-121-WP). DCs were differentiated from monocytes from peripheral blood of healthy donors and pulsed with CSC total RNA. Maturation of the CSC RNA-pulsed DCs was confirmed by increased expression of CD11c, CD40, CD83, CD86 and HLA-DR, as well as reduced CD14 expression compared with monocytes. Total lymphocytes co-cultured with CSC RNA-pulsed DCs were analyzed by flow cytometry for markers including CD3, CD4, CD8, CD16 and CD56. The results revealed that the co-cultures contained mostly cytotoxic CD8+ T lymphocytes followed by CD4+ T lymphocytes and smaller populations of natural killer (NK) and NKT cells. ELISA was used to measure IFN-γ production, and it was revealed that activated CD4+ and CD8+ lymphocytes produced more IFN-γ compared with naïve T cells, suggesting that CD8+ T cells were effector T cells. CSC RNA was a more efficient antigen source compared with RNA from mixed BC cells for activating tumor antigen-specific killing by T cells. These CSC-specific effector T cells significantly induced BC cell apoptosis at a 20:1 effector T cell:tumor cell ratio. Of note, the breast CSCs cultures demonstrated resistance to effector T cell killing, which was in part due to increased expression of programmed death ligand 1 in the CSC population. The present study highlights the potential use of CSC RNA for priming DCs in modulating an anticancer immune response against BC.

High ASMA+ Fibroblasts and Low Cytoplasmic HMGB1+ Breast Cancer Cells Predict Poor Prognosis.

INTRODUCTION: The influence of cancer-associated fibroblasts (CAFs) and high mobility group box 1 (HMGB1) has been recognized in several cancers, although their roles in breast cancer are unclear. The present study aimed to determine the levels and prognostic significance of α-smooth muscle actin-positive (ASMA+) CAFs, plus HMGB1 and receptor for advanced glycation end products (RAGE) in cancer cells. MATERIALS AND METHODS: A total of 127 breast samples, including 96 malignant and 31 benign, were examined for ASMA, HMGB1, and RAGE by immunohistochemistry. The χ2 test and Fisher's exact test were used to test the association of each protein with clinicopathologic parameters. The Kaplan-Meier method or log-rank test and Cox regression were used for survival analysis. RESULTS: ASMA+ fibroblast infiltration was significantly increased in the tumor stroma compared with that in benign breast tissue. The levels of cytoplasmic HMGB1 and RAGE were significantly greater in the breast cancer tissue than in the benign breast tissues. High ASMA expression correlated significantly with large tumor size, clinical stage III-IV, and angiolymphatic and perinodal invasion. In contrast, increased cytoplasmic HMGB1 correlated significantly with small tumor size, pT stage, early clinical stage, luminal subtype (but not triple-negative subtype), and estrogen receptor and progesterone receptor expression. The levels of ASMA (hazard ratio, 14.162; P = .010) and tumor cytoplasmic HMGB1 (hazard ratio, 0.221; P = .005) could serve as independent prognostic markers for metastatic relapse in breast cancer patients. The ASMA-high/HMGB1-low profile provided the most reliable prediction of metastatic relapse. CONCLUSION: We present for the first time, to the best of our knowledge, the potential clinical implications of the combined assessment of ASMA+ fibroblasts and cytoplasmic HMGB1 in breast cancer.