Abstract 1456: Integrin beta4-induced mitophagy promotes the lactate production of cancer-associated fibroblasts in breast cancer

Abstract

Abstract Integrin beta4 neoexpression is induced in cancer-associated fibroblasts (CAFs) by some triple negative breast cancer cells (MDA-MB-231 and BT-20) through a contact-dependent manner. Integrin beta4 expression is well known to contribute to the migration and survival of cancer cells. However, there is very little known about the role of integrin beta4 expression in CAFs, especially in the aspect of tumor progression. In our study, we found that the exogenous expression of integrin beta4 increased the lactate production of CAFs. The observation made us to hypothesize that integrin beta4 neoexpression is associated with the mitophagy, a cause for aerobic glycolysis, in CAFs. To confirm the assumption, the expression alteration of mitophagy-related genes was first screened in the CAF transfected with integrin beta4 overexpression plasmid. BCL2 interacting protein 3 like (BNIP3L) and microtubule associated protein 1 light chain 3 alpha-II (LC3-II) were significantly upregulated in the integrin beta4 overexpressing CAFs, which was reversed both in the knockdown of integrin beta4 expression and the treatment with an integrin beta4 inhibitor. Autophagosome maturation and lysosomal fusion were also increased in the integrin beta4 overexpressing CAFs compared to the control. Phosphorylation level of c-Jun was upregulated by integrin beta4 overexpression in CAFs and was able to bind to the putative promoter regions of BNIP3L and LC3-II. Taken together, these results demonstrate that integrin beta4 neoexpression induces upregulation of BNIP3L and LC3-II ultimately leading to mitophagy in CAFs, contributing to cancer metabolism via mitophagy-induced lactate production, namely reverse Warburg effect. Citation Format: Jin Sol Sung, Suki Kang, Joo Hyun Lee, Seong Gyeong Mun, Baek Gil Kim, Nam Hoon Cho. Integrin beta4-induced mitophagy promotes the lactate production of cancer-associated fibroblasts in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1456.