gastrin-releasing-peptide and Carcinoma--Hepatocellular

There is a continuing need for innovative alternative therapies for liver cancer. DNA vaccines for hormone/ growth factor immune deprivation represent a feasible and attractive approach for cancer treatment. We reported a preventive effect of a DNA vaccine based on six copies of the B cell epitope GRP18-27 with optimized adjuvants against H22 hepatocarcinoma. Vaccination with pCR3.1-VS-HSP65-TP-GRP6-M2 (vaccine) elicited much higher level of anti-GRP antibodies and proved efficacious in preventing growth of transplanted hepatocarcinoma cells. The tumor size and weight were significantly lower (p<0.05) in the vaccine subgroup than in the control pCR3.1-VS-TP-HSP65-TP-GRP6, pCR3.1-VS-TP-HSP65-TP-M2 or saline subgroups. In addition, significant reduction of tumor-induced angiogenesis associated with intradermal tumors of H22 cells was observed. These potent effects may open ways towards the development of new immunotherapeutic approaches in the treatment of liver cancer.

Topics: Adjuvants, Immunologic; Animals; Antibodies; Cancer Vaccines; Carcinoma, Hepatocellular; Gastrin-Releasing Peptide; Immunization; Liver Neoplasms; Male; Mice; Mice, Inbred BALB C; Neovascularization, Pathologic; Tumor Cells, Cultured; Vaccines, DNA

Gastrin-releasing peptide (GRP) plays an important role in regulating tumor growth and migration. However, little is known about its role in human hepatocellular carcinoma (HCC) cells. This study explored the effect of GRP on the growth of HCC HepG2 cells and the underlying mechanisms. Expression of GRP and its cognate receptor (GRPR) were detected by immunocytochemisty, reverse transcription-PCR and Western blotting and compared between two human HCC cell lines (HepG2 and MHCC97H) and a normal hepatic cell line (HL-7702). The effects of GRP on cell proliferation and signaling pathways were examined by Western blotting, MTT assay and flow cytometry. Both GRP and GRPR were overexpressed in HepG2 and MHCC97H cells. GRP activated MAPK/ERK1/2 in HepG2 cells, leading to enhanced proliferation, reduced apoptosis and accelerated cell cycle progression. The effect of GRP on ERK1/2 was effectively attenuated by the GRPR antagonist PD176252 or MEK inhibitor U0126, but not by the TNF-alpha protease inhibitor TAPI-1 or the EGFR tyrosine kinase inhibitor PD153035. The effect of GRP on the growth of HepG2 cells was significantly attenuated by PD176252 or U0126. GRP serves as a mitogen for HepG2 and MHCC97H cells. GRP promotes the growth of HepG2 cells through interaction with GRPR co-expressed in tumor cells, and subsequently activates MAPK/ERK1/2 via EGFR-independent mechanisms.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Cell Proliferation; Cells, Cultured; Enzyme Activation; ErbB Receptors; Gastrin-Releasing Peptide; Gene Expression Regulation, Neoplastic; Hep G2 Cells; Humans; Indoles; Liver Neoplasms; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Quinazolines; Receptors, Bombesin