Tumor suppressor lnc-CTSLP4 inhibits EMT and metastasis of gastric cancer by attenuating HNRNPAB-dependent Snail transcription

Tumor metastasis is a crucial impediment to the treatment of gastric cancer (GC), and the epithelial-to-mesenchymal transition (EMT) program plays a critical role for the initiation of GC metastasis. Thus, the aim of this study is to investigate the regulation of lnc-CTSLP4 in the EMT process during GC progression. We found that lnc-CTSLP4 was significantly downregulated in GC tumor tissues compared with adjacent non-tumor tissues, and its levels in GC tumor tissues were closely correlated with tumor local invasion, TNM stage, lymph node metastasis, and prognosis of GC patients. Loss- and gain-of-function assays indicated that lnc-CTSLP4 inhibited GC cell migration, invasion, and EMT in vitro, as well as peritoneal dissemination in vivo. Mechanistic analysis demonstrated that lnc-CTSLP4 could bind with Hsp90α/heterogeneous nuclear ribonucleoprotein AB (HNRNPAB) complex and recruit E3-ubiquitin ligase ZFP91 to induce the degradation of HNRNPAB, thus suppressing the transcriptional activation of Snail and ultimately reversing EMT of GC cells. Taken together, our results suggest that lnc-CTSLP4 is significantly downregulated in GC tumor tissues and inhibits metastatic potential of GC cells by attenuating HNRNPAB-dependent Snail transcription via interacting with Hsp90α and recruiting E3 ubiquitin ligase ZFP91, which shows that lnc-CTSLP4 could serve as a prognostic biomarker and therapeutic target for metastatic GC.