DNMT1/miR-152-3p/SOS1 signaling axis promotes self-renewal and tumor growth of cancer stem-like cells derived from non-small cell lung cancer.

BACKGROUND: CSLCs(Cancer stem cell-like cells), which are central to tumorigenesis, are intrinsically influenced by epigenetic modifications. This study aimed to elucidate the underlying mechanism involving the DNMT1/miR-152-3p/SOS1 axis in regulating the self-renewal and tumor growth of LCSLCs (lung cancer stem-like cells). MATERIALS AND METHODS: Target genes of miR-152-3p were predicted using TargetScan Human 8.0. Self-renewal and tumor growth of LCSLC were compared in suspension-cultured non-small cell lung cancer (NSCLC) cell lines H460 and A549 cell-derived globe cells. Functional effects of the DNMT1/miR-152-3p/SOS1 axis were assessed through gain-of-function experiments in vitro and in vivo. Additionally, luciferase reporter assays were employed to analyze the interaction among DNMT1, miR-152-3p, and SOS1. RESULTS: Our findings highlight a negative interaction between DNMT1 and miR-152-3p, resulting in reduced miR-152-3p level. This, in turn, leads to the alleviation of the inhibitory effect of miR-152-3p on the target gene SOS1, ultimately activating SOS1 and playing an essential role in self-renewal and tumor growth of LCSLC. However, the alteration of SOS1 does not affect DNMT1/miR-152-3p regulation. Therefore, it is reasonable to infer that the DNMT1/miR-152-3p negative feedback loop critically sustains self-renewal and tumor growth of LCSLC through SOS1. CONCLUSIONS: This study reveals a novel mechanism underpinning self-renewal and tumor growth of CSLC (cancer stem cell) in NSCLC and identifies potential therapeutic targets for NSCLC treatment.

VPS33B interacts with NESG1 to suppress cell growth and cisplatin chemoresistance in ovarian cancer.

The pathogenesis and cisplatin chemoresistance of ovarian cancer (OC) are still unclear. Vacuolar protein sorting-associated 33B (VPS33B) has not been reported in OC to date. In this study, immunohistochemistry was used to detect VPS33B protein expression between OC and ovarian tissues. MTT, EdU, colony formation, cell cycle, in vivo tumorigenesis, western blot, ChIP, EMSA, co-immunoprecipitation (CoIP), qRT-PCR, and microconfocal microscopy were used to explore the function and molecular mechanisms of VPS33B in OC cells. The results of the present study demonstrated that VPS33B protein expression was obviously reduced in OC compared with that in ovarian tissues. Overexpressed VPS33B suppressed cell cycle transition, cell growth, and chemoresistance to cisplatin in vitro and in vivo. Analysis of the mechanism indicated that overexpressed VPS33B regulated the epidermal growth factor receptor (EGFR)/PI3K/AKT/c-Myc/p53/miR-133a-3p feedback loop and reduced the expression of the cell cycle factor CDK4. Nasopharyngeal epithelium-specific protein 1 (NESG1) as a tumor suppressor not only interacted with VPS33B, but was also induced by VPS33B by the attenuation of PI3K/AKT/c-Jun-mediated transcription inhibition. Overexpressed NESG1 further suppressed cell growth by mediating VPS33B-modulated signals in VPS33B-overexpressing OC cells. Finally, NESG1 induced VPS33B expression by reducing the inhibition of PI3K/AKT/c-Jun-mediated transcription. Our study is the first to demonstrate that VPS33B serves as a tumor suppressor, and VPS33B can interact with NESG1 to suppress cell growth and promote cisplatin sensitivity by regulating the EGFR/PI3K/AKT/c-Myc/p53/miR-133a-3p feedback loop in OC cells.