Methyltransferase-like 3 facilitates the stem cell properties of esophageal cancer by upregulating patched homolog 1 via N6-methyladenosine methylation.

ABSTRACT

Patched homolog 1 (PTCH1) has been proven to facilitate cell proliferation and self-renewal in esophageal cancer (EC). The present study intended to exploit the influence of PTCH1 on EC cells and the potential mechanisms. PTCH1 and methyltransferase-like 3 (METTL3) expression were examined by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot in EC cell lines. Following the loss- and gain-of-function assays, cell proliferation was examined by cell counting kit (CCK)-8 and clone formation assays, invasion and migration by Transwell and scratch assays, and the sphere-forming ability of stem cells by cell sphere-forming assay. The expression of stemness genes NANOG homeobox protein (NANOG), octamer-binding transcription factor 4 (Oct4), and sex-determining region Y-box 2 (SOX2) was detected by Western blot. Methylated RNA immunoprecipitation (Me-RIP) assay was performed to test N6-methyladenosine (m6A) modification levels of PTCH1 mRNA, RIP and photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) assays to assess the binding of METTL3 to PTCH1, and actinomycin D treatment to examine PTCH1 mRNA stability. A xenograft tumor model in nude mice was established for further in vivo verification. PTCH1 and METTL3 expression was high in EC cells. Knockdown of METTL3 reduced m6A level and stability of PTCH1 mRNA. Knockdown of PTCH1 or METTL3 declined invasion, proliferation, migration, and NANOG, Oct4, and SOX2 levels in EC cells, and reduced sphere-forming abilities of EC stem cells. Overexpression of PTCH1 abolished the suppressive effect of METTL3 knockdown on EC cells in vitro. METTL3 knockdown repressed tumor growth in nude mice, which was negated by further overexpressing PTCH1. METTL3 facilitated growth and stemness of EC cells via upregulation of PTCH1 expression by enhancing PTCH1 m6A modification.NEW & NOTEWORTHY PTCH1 has been proved to facilitate cell proliferation and self-renewal in esophageal cancer. We studied the upstream regulation mechanism of PTCH1 by METTL3 through m6A modification. Our results provide a new target and theoretical basis for the treatment of esophageal cancer.