ZFHX3 acts as a tumor suppressor in prostate cancer by targeting FTO-mediated m⁶A demethylation

Zinc-finger homeobox 3 (ZFHX3, also known as ATBF1) suppresses prostatic tumorigenesis. ZFHX3 is frequently found to have numerous deletions in human prostate cancer (PCa). However, the underlying molecular function of ZFHX3 during prostatic tumorigenesis is not well understood. N⁶-methyladenosine (m⁶A) modification in RNA plays a critical role in the development of cancers; however, the relationship between ZFHX3 and m⁶A modification is largely unknown in PCa. In this study, we found that ZFHX3 knockdown decreased total m⁶A levels through enhancing the transcriptional activity of FTO in PCa cells. Importantly, FTO inhibition suppressed cell proliferation and rescued the promoting function of ZFHX3 knockdown on cell proliferation. In vivo, we verified that FTO was upregulated and ZFHX3 was decreased in PCa patients and that a high level of ZFHX3 is indispensable for low FTO expression and is correlated with better patient survival. Through transcriptome sequencing and MeRIP sequencing, we revealed that E2F2 and CDKN2C were the direct targets of FTO-mediated m⁶A modification and ZFXH3 was required for the regulation of FTO on E2F2 and CDKN2C expression. Unexpectedly, we uncovered that ZFHX3 expression was in return regulated by FTO in an m⁶A-dependent way. These findings establish a novel crosstalk mechanism between ZFHX3 and FTO in prostatic tumorigenesis.