The novel mechanism of Med12-mediated drug resistance in a TGFBR2-independent manner.

Inevitable emergence of drug resistance is the biggest hurdle to both chemotherapies and targeted therapies. Understanding the resistance mechanisms will contribute to identification of biomarkers for predicting response to therapy and design new therapeutic strategies to overcome drug resistance in human cancers. The type II transforming growth factor (TGF)-β receptor gene (TGFBR2) is frequently frameshift mutated in several cancer types, especially in colorectal, endometrium and gastric cancers cells. Here, we found that Med12, a component of the transcriptional mediator complex, plays a role in modulating chemosensitivity in TGFBR2 deficient cancer cells. Loss of Med12 leads to chemoresistance in multiple TGFBR2 deficient cancer cells. Interestingly, RNA sequencing data revealed that interferon IFN-related DNA damage resistance signature (IRDS) is upregulated in Med12 knockdown cancer cells. And the expression of IRDS pattern is negatively correlated with chemosensitivity. Therefore, our study identifies a novel mechanism of Med12-mediated drug resistance, which is a TGFBR-independent manner.