FHL1 inhibits the growth of tongue squamous cell carcinoma cells via G1/S cell cycle arrest

Abstract

Abstract. Four and a half LIM protein 1 (FHL1) has been characterized as a tumor suppressor in various types of tumor. However, the biological function and underlying mechanism of FHL1 in tongue squamous cell carcinoma (TSCC) remain to be elucidated. The present study demonstrated that FHL1 inhibits anchorage-dependent and -independent growth of TSCC cells in vitro and tumor growth in nude mice, as determined by cell proliferation and soft agar assays. Knockdown of FHL1 with FHL1 small interfering RNA (siRNA) promoted tumor growth in nude mice. Mechanistically, flow cytometric analysis showed that knockdown of FHL1 promoted G1/S cell cycle progression. Furthermore, expression of cell cycle-associated regulators, cyclin D and cyclin E, were detected by western blotting and reverse transcription-quantitative polymerase chain reaction. Cyclin D and cyclin E were markedly elevated at both the protein and mRNA level in the FHL1 siRNA-transfected cells. These results suggested that FHL1 has a tumor suppressive role in TSCC and that FHL1 may be a useful target for TSCC gene therapy. IntroductionSquamous cell carcinoma (SCC) of the oral cavity is the sixth most frequent solid cancer worldwide (1). Tongue squamous cell carcinoma (TSCC) is the most common type of oral cancer and is well known for its high rate of proliferation and lymph node metastasis. The majority of TSCC patients are associated with smoking, heavy alcohol use and HPV infection (2-4). According to the American Cancer Society (5), while overall new cancer cases increased ~8%, new cases of TSCC increased by >37% in the same period. This indicates a major health problem associated with TSCC and suggests the immediate requirement for an improved understanding of this disease. To prevent and improve the outcomes of TSCC, it is necessary to further understand the molecular mechanism underlying the development and progression of TSCC and to develop new target therapies.Four and a half LIM protein 1 (FHL1) is a member of the FHL protein family, which contains four complete LIM domains and an N-terminal half LIM domain (6). It has been reported that LIM domains function in protein-protein interactions with transcription factors, cell-signaling molecules and cytoskeleton-associated proteins (6,7). Previously, FHL1 has been demonstrated to be important in carcinogenesis. FHL1 expression is downregulated in various types of malignancy, including breast cancer, liver cancer, kidney cancer, prostate cancer, gastric cancer, lung cancer and oral squamous cell carcinoma (OSCC) (8-13). FHL1 exerts its tumor suppressive role via multiple mechanisms. FHL1 activates the tumor suppressor gene p21 (WAF1/CIP1) and represses the oncogene c-myc through interaction with Smad2, Smad3 and Smad4 in liver cancer cells (10). In breast cancer cells, FHL1 interacted with estrogen receptors and thus decreases the expression of pS2 and cathepsin D, two estrogen-responsive genes (9). In addition, FHL1 induces G1 and G2/M cell cycle arrest in lung cancer cells by inhibiting the expression o...

MiR-183-5p Promotes Proliferation, Metastasis and Angiogenesis in Breast Cancer Cells through Negatively Regulating Four and a Half LIM Protein 1

“…Four and a half LIM protein 1 (FHL1), which has been identified as a tumor suppressor gene in multiple malignancies [ 6 7 8 ], suppresses the growth of tongue squamous cell carcinoma cells through G1/S cell cycle arrest [ 7 ]. FHL1 silencing promotes the growth of HepG2 and HeLa cells [ 8 ].…”

A Liquid Chromatography with Tandem Mass Spectrometry-Based Proteomic Analysis of Cells Cultured in DMEM 10% FBS and Chemically Defined Medium Using Human Adipose-Derived Mesenchymal Stem Cells

“…In this study, the proteins expressed only in the CDM group were POTEKP, TAGLN3, TF, MT2A (a key protein involved in endothelial cell proliferation and migration [ 42 ]), HP, DHCR24 (a key protein involved in cell homeostasis and cholesterol biosynthesis [ 43 ]), NQO1 (a key protein involved in cellular adaptation to stress [ 44 ]), and TRAP1 (a key protein of the molecular chaperone involved in the regulation of energetic metabolism in cancer cells [ 45 ]). The proteins expressed only in the DMEM group were PDLIM5 (proteins phosphorylated by AMPK activation that suppress cell migration [ 46 ]), PDLIM7 (a key protein of scaffolds for the formation of multiprotein complexes [ 47 ]), Integrin alpha 5 (ITGA5), ASS1 (an enzyme involved in the clearance of nitrogenous waste via the urea cycle and de novo arginine biosynthesis [ 48 ]), FHL1 (inhibits the growth of cancer cells via G1/S cell cycle arrest [ 49 ]), and voltage-dependent anion channel 3 (VDAC3). These results indicate that the proteins specifically expressed in the CDM and DMEM groups included proteins involved in cell adhesion, cell migration, cell cycle regulation, and lipid metabolism.…”

Minichromosome maintenance protein 2 and 3 promote osteosarcoma progression via DHX9 and predict poor patient prognosis

“…CTBP1, a co-repressor of tumor suppressor genes, increases breast tumor growth in vitro and in preclinical orthotopic xenograft models [20]. FHL1 has a tumor-suppressive role in tongue squamous cell carcinoma and accordingly may be a useful target for gene therapy [21]. As Rb and IMPDH2 are related to the progression of osteosarcoma [22, 23], siRNA transfection and a CCK-8 assay were performed for the functional screening of the other 9 nuclear proteins.…”