Livin enhances tumorigenesis by regulating the mitogen-activated protein kinase signaling pathway in human hypopharyngeal squamous cell carcinoma

Abstract

Livin, a member of the human inhibitor of apoptosis protein (IAP) family, is expressed at high levels in various human cancer tissues and may have prognostic significance. The aim of the present study was to evaluate the effect of Livin on tumor cell behavior and oncogenic signaling pathways in human hypopharyngeal squamous cell carcinoma (HSCC). Reverse transcription-quantitative polymerase chain reaction and western blot analyses were used to determine the mRNA and protein expression levels, respectively. A cell proliferation assay and cell cycle analysis were used to assess the functional effects of small interfering RNA-mediated Livin knockdown. Livin was overexpressed in fresh HSCC tissues, compared with the adjacent normal mucosa. Livin knockdown led to significantly reduced cell proliferation and cell cycle arrest in the G1 phase of the human HSCC cells. The expression levels of c-myc, cyclin D1, cyclin D3, cyclin-dependent kinase (CDK)4 and CDK6 were decreased. The phosphorylation levels of extracellular signal-regulated kinase 1/2, p38, c-Jun N-terminal kinase and Akt were also decreased by Livin knockdown in the HSCC cells. Taken together, the results of the present study suggested that Livin may enhance tumorigenesis by modulating the mitogen-activated/Akt signaling pathways in human HSCC.