CSTF2T up-regulates IGHG1 by binding to ZEB1 to promote melanoma cell proliferation, migration, and invasion

Objectives: Melanoma progression involves multiple molecular pathways. In this study, we explored the effect of immunoglobulin heavy constant gamma 1 (IGHG1) on melanoma progression.

Methods: IGHG1, zinc finger E-box binding homeobox 1 (ZEB1), and cleavage stimulation factor subunit 2 tau variant (CSTF2T) expression levels were measured by quantitative reverse-transcription polymerase chain reaction and western blot. BALB/c nude mice were subcutaneously injected with A375 cells to develop a transplantation tumor model, 4 weeks after which the tumor tissues were collected. Cell proliferation, cell invasion, and cell migration of A375 and SK-MEL-28 cells were measured after gain- and loss-of-function of IGHG1, ZEB1, and CSTF2T. Binding of ZEB1 to the IGHG1 promoter was assayed by chromatin immunoprecipitation and dual-luciferase reporter gene assays, while binding of CSTF2T to ZEB1 mRNA was investigated by RNA immunoprecipitation and RNA pull-down assays.

Results: IGHG1, ZEB1, and CSTF2T were all highly expressed in human melanoma cell lines. In A375 and SK-MEL-28 cells, ZEB1 binds directly to the IGHG1 promoter. ZEB1 silencing reduced IGHG1 expression and melanoma cell proliferative, invasive, and migratory properties, and these cellular effects were nullified by overexpression of IGHG1. CSTF2T binds directly to ZEB1 mRNA. Silencing of CSTF2T diminished ZEB1 expression and restrained melanoma cell proliferative, invasive, and migratory capabilities. The impacts of CSTF2T silencing on melanoma cells were counteracted by concomitant overexpression of ZEB1. CSTF2T knockdown reduced tumor volume and weight in nude mice.

Conclusions: The CSTF2T-ZEB1-IGHG1 axis promotes melanoma cell proliferation and invasion.