Grp78 promotes the invasion of hepatocellular carcinoma

Abstract

BackgroundGlucose regulated protein 78 (Grp78) is involved in the invasion and metastasis in many human cancers including gastric cancer, breast cancer, prostate cancer. But the role of Grp78 in the invasion of human hepatocellular carcinoma has not been reported. In this article, we examined if Grp78 was associated with the invasion of hepatocellular carcinoma and explored the possible underlying mechanism.MethodsThe Grp78 and FAK expression levels in 44 patients with hepatocellular carcinoma were examined using immunohistochemistry. Grp78 overexpressing SMMC7721 cells were established by pcDNA3.1 (+)-Grp78 transfection and screened by G418. Grp78 and FAK levels in Grp78 overexpressing cells were down-regulated by siRNA transfection. The invasion status of tumor cells was evaluated by transwell assay in vitro, and chick embryo metastasis model in vivo. Cell spreading was determined by cell spreading assay, and quantitatively measured by Orisis software HUG. Grp78, pY397 FAK, pY576/577 FAK and FAK levels were detected by western blot. RhoA activity was detected by GST pulldown assay. The distribution of actin cytoskeleton was observed by fluorescent staining.ResultsGrp78 expression levels in 44 patients with hepatocellular carcinoma were negatively correlated with tumor grading, and positively correlated with portal invasion and intra-hepatic invasion. Overexpression of Grp78 in SMMC7721 cells promoted the invasion of cancer cells in vitro and in vivo, and this increase in tumor cell invasion was blocked by Grp78 siRNA knockdown. Our results also revealed that overexpression of Grp78 in SMMC7721 cells accelerated the process of cell spreading and promoted lamellipodia formation. Further analysis showed that overexpression of Grp78 in SMMC7721 cells increased pY397 and pY576/577 levels of FAK. Grp78 siRNA knockdown decreased FAK activation and activity. Our results also revealed that Grp78 overexpression in SMMC7721 cells decreased RhoA-GTP level, and Grp78 siRNA knockdown rescued RhoA-GTP level in Grp78 overexpressing cells, indicating Grp78 inhibited RhoA activity in hepatocellular carcinoma cells. Furthermore, overexpression of Grp78 in SMMC7721 cells increased phospho-p190RhoGAP level. FAK siRNA knockdown in Grp78 overexpressing cells reversed phospho-p190RhoGAP level. These data suggested that Grp78 inhibited RhoA activity by up-regulated phospho-p190RhoGAP level and Grp78 mediated p190RhoGAP phosphorylation is FAK dependent.ConclusionGrp78 promoted the invasion of hepatocellular carcinoma both in vitro and in vivo. Overexpression of Grp78 in hepatocellular carcinoma cells enhanced the activation and activity of FAK which negatively regulated Rock kinase activity by promoting the phosphorylation of p190RhoGAP.

Expression of GRP78, Master Regulator of the Unfolded Protein Response, Increases Chemoresistance in Pancreatic Ductal Adenocarcinoma

“…2). GRP78 expression has been linked to drug resistance and malignancy in brain (25,26), liver (27,28), lung (29), and breast cancers (30,31). Our studies extend these findings by showing the prevalence and clinical significance of GRP78 expression in PDAC.…”

Glucose‐regulated protein 58 modulates cell invasiveness and serves as a prognostic marker for cervical cancer

“…(30) The microenvironment of tumors causes physiological ER stress, and cells trigger the unfolded protein response (UPR) to protect tumors from stress-induced cell death. Many UPR-related proteins, such as Grp78, (31) Grp94 (32) and calreticulin, (33) are involved in tumorigenesis and tumor progression. In cervical cancer cell lines, the UPR-related proteins such as Grp78, Grp94 and activating transcription factor 4 (ATF4) are associated with tolerance to ER stress, apoptosis and sensitivities to X-ray and anticancer drugs.…”

Nanoparticles inhibit cancer cell invasion and enhance antitumor efficiency by targeted drug delivery via cell surface-related GRP78

“…26,27 Recent investigations 10,11,15 have revealed that specific mole cules targeting cell surface agents could administrate entry and subsequent cytosolic access of NPs into living cells, for example, carbohydrate, folic acid, transferrin, and some peptides. From Figure 3, we can see that GRP78 is more highly expressed on the cell surface of SMMC-7721 cells than on the cell surface of PLC cells, and many studies [23][24][25] have shown that GRP78 plays an important role in tumor cells' invasion and metastasis. After investigating the adhesion and invasion abilities of SMMC-7721 and PLC, we found that SMMC-7721 cells are stronger than PLC cells.…”

“…24,25 Blockade of cell surface GRP78 inhibited the proliferation and induced apoptosis in melanoma and prostate cancer. 26,27 Inhibition of cell surface GRP78 inhibited the tumor invasion and metastasis in hepatocellular carcinoma and colorectal cancer cell.…”