The aim of the present study was to investigate the expression and function of metastasis-associated in colon cancer 1 (MACC1) in tongue squamous cell carcinoma (TSCC) and its relationship with the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) (CD147). Levels of MACC1 and EMMPRIN expression were analyzed in 65 paraffin‑embedded tissue specimens of TSCC and in the adjacent non-cancerous tissues using immunohistochemistry (IHC). MACC1 expression was highly associated with lymphatic metastasis and EMMPRIN expression. Overexpression of MACC1 was significantly correlated with poor overall patient survival. A small interfering RNA (siRNA) was delivered into TSCCA cells to downregulate MACC1 expression. The CCK-8 assay showed that TSCCA cell proliferation was markedly reduced and that cisplatin resistance was attenuated. The suppression of MACC1 promoted the apoptosis of the TSCCA cell line. A Transwell experiment demonstrated that the migration and invasion abilities of the TSCCA cells were extremely downregulated. An ELISA experiment and western blotting revealed that the secretion of urokinase-type plasminogen activator system (uPA) in the supernatant of the culture medium and uPA expression were significantly reduced. Experiments revealed that the secretion of metalloproteinase 2 (MMP2) in the supernatant of the culture medium and MMP2 expression were not affected. MACC1 may serve as a novel biomarker and therapeutic target for TSCC.
STEAP3 (Six-transmembrane epithelial antigen of the prostate 3, TSAP6, dudulin-2) has been reported to be involved in tumor progression in human malignancies. Nevertheless, how it participates in the progression of human cancers, especially HCC, is still unknown. In the present study, we found that STEAP3 was aberrantly overexpressed in the nuclei of HCC cells. In a large cohort of clinical HCC tissues, high expression level of nuclear STEAP3 was positively associated with tumor differentiation and poor prognosis (p < 0.001), and it was an independent prognostic factor for HCC patients. In HCC cell lines, nuclear expression of STEAP3 significantly promoted HCC cells proliferation by promoting stemness phenotype and cell cycle progression via RAC1-ERK-STAT3 and RAC1-JNK-STAT6 signaling axes. Through upregulating the expression and nuclear trafficking of EGFR, STEAP3 participated in regulating EGFR-mediated STAT3 transactivity in a manner of positive feedback. In summary, our findings support that nuclear expression of STEAP3 plays a critical oncogenic role in the progression of HCC via modulation on EGFR and intracellular signaling, and it could be a candidate for prognostic marker and therapeutic target in HCC.
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