LncRNA PCAT6 promotes progression and metastasis of colonic neuroendocrine carcinoma via MAPK pathway

Colonic neuroendocrine carcinomas (NECs) are highly malignant and invasive with poor prognosis. Long noncoding RNAs (LncRNAs) participate in the tumorigenesis and metastasis of multiple cancers.

To detect the roles and mechanisms of lncRNA prostate cancer associated transcript 6 (PCAT6) in the progression of colonic NEC.

Human NEC and adjacent normal samples were collected for immunohistochemistry staining of CgA and real-time quantitative polymerase chain reaction (RT-qPCR) of PCAT6 mRNA level. Subcutaneous xenograft tumor model and lung metastasis model were established in nude mice. The lung tissues were stained by hematoxylin and eosin to assess pulmonary metastasis. The expression of epithelial-mesenchymal transition (EMT)-related markers and pathway-related genes was measured by RT-qPCR and western blotting. CD56 expression was assessed by immunofluorescence staining. The biological functions of PCAT6 were examined by cell counting kit-8, colony formation assays, Transwell assays and wound healing assays. The interaction between PCAT6 and its potential downstream target was verified by luciferase reporter assays.

LncRNA PCAT6 was upregulated in human NEC samples and LCC-18 cells, and its high expression was positively correlated with poor prognosis in patients with colonic NEC. Additionally, the expression of PCAT6 was positively associated with the proliferation, migration, invasion, and EMT of LCC-18 cells. Moreover, PCAT6 facilitated tumor growth, lung metastasis and EMT in xenografts. Mechanistically, PCAT6 promoted the activation of MAPK to enhance the EMT in colonic NEC by targeting miR-326.

In conclusion, lncRNA PCAT6 accelerates the process of colonic NEC by activating ERK/p38 MAPK signaling through targeting miR-326. These results might provide useful information for exploring the potential therapeutic targets in colonic NEC.