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

Breast Cancer Res. 2023 Jul 21;25(1):86. doi: 10.1186/s13058-023-01684-7.

Abstract

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.

Keywords: CAR-T cell; Cancer-associated fibroblast; Doxorubicin; Folate receptor-α; IL-6; PD-L1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • B7-H1 Antigen / genetics
  • Cancer-Associated Fibroblasts*
  • Humans
  • Interleukin-6 / genetics
  • Proto-Oncogene Proteins c-akt
  • Receptors, Chimeric Antigen*
  • STAT3 Transcription Factor / genetics
  • T-Lymphocytes
  • Triple Negative Breast Neoplasms* / genetics

Substances

  • Receptors, Chimeric Antigen
  • Interleukin-6
  • Proto-Oncogene Proteins c-akt
  • B7-H1 Antigen
  • STAT3 protein, human
  • STAT3 Transcription Factor