Involvement of RhoA and RalB in geranylgeranyltransferase I inhibitor-mediated inhibition of proliferation and migration of human oral squamous cell carcinoma cells

• Published in: Cancer chemotherapy and pharmacology Vol. 68; no. 3; pp. 559 - 569
• Main Authors: Hamada, Masakazu, Miki, Tetsuei, Iwai, Soichi, Shimizu, Hidetaka, Yura, Yoshiaki
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2011; Springer; Springer Nature B.V
• Subjects: Alkyl and Aryl Transferases - antagonists & inhibitors; Antineoplastic agents; Biological and medical sciences; Blotting, Western; Cancer Research; Carcinoma, Squamous Cell - drug therapy; Carcinoma, Squamous Cell - enzymology; Carcinoma, Squamous Cell - pathology; Cell Fractionation; Cell Line, Tumor; Cell Movement - drug effects; Cell Proliferation - drug effects; Cyclin-Dependent Kinase Inhibitor Proteins - pharmacology; Cytoskeleton - metabolism; Cytoskeleton - ultrastructure; GTP Phosphohydrolases - metabolism; Humans; Indicators and Reagents; Medical sciences; Medicine; Medicine & Public Health; Mouth Neoplasms - drug therapy; Mouth Neoplasms - enzymology; Mouth Neoplasms - pathology; Neoplasm Invasiveness - pathology; Oncology; Original Article; Otorhinolaryngology. Stomatology; Pharmacology. Drug treatments; Pharmacology/Toxicology; Protein Prenylation - drug effects; ral GTP-Binding Proteins - genetics; ras Proteins - biosynthesis; rhoA GTP-Binding Protein - genetics; RNA, Small Interfering; Tumors; Upper respiratory tract, upper alimentary tract, paranasal sinuses, salivary glands: diseases, semeiology; Wound Healing; Rho; Geranylgeranyltransferase I inhibitor; Oral squamous cell carcinoma; Ral; Migration; GGTase; Human; Cell proliferation; Oral cancer; Stomatology; Malignant tumor; In vitro; Oral cavity disease; Inhibitor; Inhibition; Cell; Cell migration; Cancer
• ISSN: 0344-5704; 1432-0843
• DOI: 10.1007/s00280-010-1520-9

Purpose Geranylgeranyltransferase I is required for the prenylation of the small GTPases. The effect of GGTase I inhibitors (GGTIs) on oral squamous cell carcinoma (SCC) cells was examined. Methods The GGTI-treated cells were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, flow cytometric analysis, transwell chamber assays, and immunofluorescent staining. Small GTPases were detected by immunoblot analysis, and siRNA were used for silencing RalA and RalB. Results GGTI suppressed the proliferation of oral SCC cells and induced cell cycle arrest at G 1 , but the sub-G 1 fraction was small. The expression of the cyclin-dependent kinase (CDK) inhibitor p21 Waf1/Cip1 , but not p27 Kip1 , was markedly increased by GGTI. There was an apparent increase in the expression and reduction in the membrane localization of RhoA and RalB, but not Ras and RalA. Assays with transwell chambers and wound healing and invasion revealed the migrative and invasive capabilities of SAS cells to be inhibited by GGTI. Actin filaments were rearranged and stress fibers and peripheral cell processes were lost, accompanying cell rounding. siRNA for RalB, but not RalA, significantly suppressed the migration of SAS cells. Conclusion These results suggest that GGTI inhibits the geranylgeranylation of RhoA and increases the p21 Waf1/Cip1 level, resulting in cell cycle arrest at G 1 to decrease cell proliferation, and that of RalB to suppress the migration and invasion by oral SCC cells. GGTIs may be useful as inhibitors of invasion and metastasis in cases of oral SCC.