Among them, the roles of MMP-2 and MMP-9 in cancer cell invasion have been wellknown

Among them, the roles of MMP-2 and MMP-9 in cancer cell invasion have been wellknown. the secretion and activity of MMP-2 but did not affect the secretion and activity of MMP-9. We also found that inhibition of the cell surface GRP78 increased E-Cadherin expression and decreased N-Cadherin level. On the contrary, forced expression of the cell surface GRP78 increased N-Cadherin expression and decreased E-Cadherin level, suggesting that this cell surface GRP78 plays crucial role in the regulation of EMT process. These findings suggest that the cell surface GRP78 plays a stimulatory role in the invasion process and may be a potential anti-invasion target for the treatment of hepatocellular carcinoma. 1. Introduction Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related AM 2233 death worldwide [1]. Although new therapeutic strategies have been constantly developed and applied to clinical treatment of HCC, the prognosis is still very poor [2]. The invasion and metastasis are one of the most important reasons for the mortality of HCC [3]. Therefore, understanding the mechanisms that facilitate the invasion and metastasis is critical for exploring new strategies for the treatment of HCC. The glucose regulated protein 78 (GRP78) is usually traditionally regarded as a resident protein of the endoplasmic reticulum (ER) and functions as a molecular chaperone [4]. In addition to its chaperoning function, many data suggest that GRP78 is usually a multifunctional protein and plays critical functions in the resistance to chemotherapy brokers, proliferation, invasion, and metastasis of many human cancers [5C9]. GRP78 is usually expressed in the endoplasmic reticulum in normal conditions but also is expressed at an elevated level on the surface of many tumors and disseminated tumor cells [10, 11]. The cell AM 2233 surface GRP78 functions as a signaling receptor and plays important functions in the regulation of the proproliferative/antiapoptotic and promigratory signaling pathways [12, 13]. Most information about its functions is derived from treatment of cancer cells with antibody directed against the C-terminal domain name or N-terminal domain name of GRP78. Treatment of prostate cancer (1-LN, DU145) and melanoma cells (A375), which express GRP78 around the cell surface, with antibody directed against the C-terminal domain AM 2233 name of GRP78, inhibited cell proliferation and induced apoptosis by activating p53 and suppressing Ras/MAPK, PI3K/AKT signaling pathways [14, 15]. Ligation of the cell surface GRP78 in teratoma cell line (NCCIT) and breast cancer cell line (MCF-7) with antibody directed against the N-terminal domain name of GRP78 decreased cell proliferation and cell adhesion by inhibiting MAPK/PI3K signaling pathway [16, 17]. The cell surface GRP78 is also involved in the regulation of the invasion and metastasis of many human cancers including prostate and colorectal cancers [18, 19]. In prostate cancer, the cell surface GRP78 activates the p21-activated kinase-2 (PAK2) signaling pathway and therefore Rabbit Polyclonal to OR52E2 facilitates the invasion and metastasis by binding with < 0.01, chi-squared test) (Figures 2(a) and 2(b)). Cell adhesion assay revealed that this N-20 antibody significantly decreased the binding abilities of cancer cells to FN-coated culture dishes. The N-20 antibody reduced the adhesion of cancer cells to FN to < 0.01, chi-squared test) (Figures 2(c) and 2(d)). These data suggested that this endogenous cell surface GRP78 facilitates the adhesion and invasion of hepatocellular carcinoma cells. Open in a separate window Physique 2 Immunoneutralization of the endogenous cell surface GRP78 inhibited the FN induced adhesion and invasion. ((a) and (b)) Transwell analysis of the invasive potential of Mahlavu and SMMC7721 cells treated with the N20 antibody. (Original magnification: 100x.) ((c) and (d)) Cell adhesion analysis of the binding ability of Mahlavu and SMMC7721 cells with the FN-coated substrate when treated with the N20 antibody. Data represent the means SD of triplicate determinations in three impartial experiments. Asterisks indicate that this differences are statistically significant (*< 0.05 versus iostype IgG treated cells; one-way ANOVA); UT, untreated; IgG goat isotype IgG; N20, the N20 antibody. 3.3. Overexpression of the Cell Surface GRP78 Promotes the Invasion and Adhesion of Hepatocellular Carcinoma Cells To further investigate the effect of exogenous cell surface GRP78 around the invasive potential of hepatocellular carcinoma cells, we constructed GRP78 KDEL motif.