MST4 inhibits human hepatocellular carcinoma cell proliferation and induces cell cycle arrest via suppression of PI3K/AKT pathway

Abstract

Objective: MST4 has exhibited functions in regulating cell polarity, Golgi apparatus, cell migration, and cancer. Mechanistically, it affects the activity of p-ERK, Hippo-YAP pathway and autophagy. The aim of this study is to further examine the functions of MST4 in hepatocellular carcinoma (HCC) and the underlying mechanism. Methods: The expression level of MST4 in HCC and noncancer adjacent liver tissues was determined by qRT-PCR and immunohistochemistry staining. Wild-type MST4 (MST4) and a dominant-negative mutant of MST4 (dnMST4) were overexpressed in HCC cell lines, respectively. CCK-8 assay, EdU incorporation assay, and soft agar assay were used to determine cell proliferation in vitro . The xenograft mouse model was employed to determine HCC cell growth in vivo . Cell cycle analysis was performed by PI staining and flow cytometry. The expression of key members in PI3K/AKT pathway was detected by Western blot analysis. Results: In our study, we reported new evidence that MST4 was frequently down-regulated in HCC tissues. Gain-of-function and loss-of-function experiments demonstrated that MST4 negatively regulated in vitro HCC cell proliferation. Additionally, MST4 overexpression suppressed Bel-7404 cell tumor growth in nude mice. Further experiments revealed that the growth-inhibitory effect of MST4 overexpression was partly due to a G1-phase cell cycle arrest. Importantly, mechanistic investigations suggested that dnMST4 significantly elevated the phosphorylation levels of key members of PI3K/AKT pathway, and the selective PI3K inhibitor LY294002 can reverse the proliferation-promoting effect of dnMST4. Conclusions: Overall, our results provide a new insight into the clinical significance, functions and molecular mechanism of MST4 in HCC, suggesting that MST4 might have a potential therapeutic value in the HCC clinical treatment.

MST4 negatively regulates the EMT, invasion and metastasis of HCC cells by inactivating PI3K/AKT/Snail1 axis

“…Next, we investigated the mechanism by which MST4 suppressed the EMT phenotype and the invasive and metastatic potential of HCC cells. In our previous study, we have unraveled an inhibitory effect of MST4 on PI3K/AKT pathway 29 . Here, we investigated whether the inactivation of PI3K/AKT pathway is essential for the suppressed EMT phenotype by MST4 high expression in HCC cells.…”

“…Another finding reported that PI3K/AKT can sustain NF-kB activation in the absence of TGF-β1, thus inducing EMT and promoting tumor formation and metastasis 60 . Our previous study illustrated that MST4 inhibits HCC cell proliferation by inactivating the PI3K/AKT signaling pathway 29 . Here, our data further confirmed that the PI3K inhibitor can reverse the EMT phenotypic change and the increased capabilities of migration and invasion of HCC cells caused by the MST4 functionally inactivation.…”

“…Western blotting was performed as previously described 29 . Briefly, the same amount of total denatured protein (20 μg) was isolated by 10% SDS-PAGE and transferred to PVDF membranes (P2120-2, Millipore) using BIO-RAD system.…”

“…In choriocarcinoma, MST4 is shown to inhibit cell migration and invasion by suppressing the TGF-β1-induced EMT program 28 . In our recent work, we found that MST4 is down-regulated in HCC, and that it suppresses HCC cell proliferation and cell cycle progression by inactivating PI3K/AKT pathway 29 . However, as the major cause of HCC progression and poor prognosis, the role of MST4 in the regulation of invasion and metastasis of HCC is worth further exploration.…”

Hippo Pathway Core Genes Based Prognostic Signature and Immune Infiltration Patterns in Lung Squamous Cell Carcinoma

“…The core components of the Hippo signaling pathway are verified as a kinase cascade, which act directly on the primary downstream effectors, the yes-associated protein (YAP) and the transcriptional coactivator with PDZ-binding motif (TAZ) by phosphorylation, and thereby suppressing transcription process of downstream targeted genes ( 13 ). Recently, it has been proved that the dysregulation of the Hippo signaling pathway lead to tumorigenesis, development and metastasis of diverse tumors, including lung adenocarcinoma ( 14 ), breast cancer ( 15 ), hepatocellular carcinoma ( 16 ), gastric cancer ( 17 ) and so on. However, fewer studies focus on the effects of the Hippo signaling pathway on LUSC.…”