fti-277 and Adenocarcinoma

To understand the role of BRAF dysfunction in the carcinogenesis and progression/development of colorectal tumors, the authors investigated genetic alterations in the BRAF gene in human colorectal neoplasms as well as the effects of an RAS inhibitor in BRAF-mutant cells. Seven colon cancer cell lines and 116 colorectal tumors (34 adenomas and 82 adenocarcinomas) were analyzed. Genetic alterations in the BRAF and K-ras genes were examined using polymerase chain reaction-single strand conformation polymorphism and direct sequencing analyses. The growth-inhibitory and apoptosis-inducing effects of the FTI-277 RAS inhibitor in colon cancer cell lines were analyzed as well. An immunohistochemical study was also performed to investigate the correlations between the clinicopathologic parameters involved in the Ki-67 labeling index and the number of apoptotic bodies in tumor cells. FTI-277 did not suppress the proliferation of BRAF-mutant cells (WiDr and TCO), but remarkably inhibited the growth of K-ras mutant cells (LoVo). Interestingly, LoVo cells underwent apoptosis by FTI-277 in a dose-dependent manner, whereas WiDr cells were resistant to this agent. In tumor samples, BRAF mutations were found in 1 (3.0%) of 33 adenomas and 6 (7.2%) of 83 adenocarcinomas. No tumor exhibited mutations in both the BRAF and K-ras genes. Neither BRAF nor K-ras mutations correlated with the Ki-67 labeling index immunohistochemically. However, the number of apoptotic bodies was significantly decreased in the BRAF-mutant tumors. Mutation in the BRAF gene may contribute to colorectal carcinogenesis by upregulating the antiapoptotic role of the RAS/RAF/MEK/ERK pathway.

Topics: Adenocarcinoma; Adenoma; Apoptosis; Base Sequence; Cell Proliferation; Colorectal Neoplasms; DNA Fragmentation; Enzyme Inhibitors; Female; Genes, ras; Humans; Immunohistochemistry; Ki-67 Antigen; Male; Methionine; Middle Aged; Mutation; Polymorphism, Single-Stranded Conformational; Proto-Oncogene Proteins B-raf; Tumor Cells, Cultured

The mechanism by which the geranylgeranyltransferase I inhibitor GGTI-298 and the farnesyltransferase inhibitor FTI-277 inhibit human tumor growth is not known. Herein, we demonstrate that in the human lung adenocarcinoma A549 cells, GGTI-298 induced a G1-G0 block whereas FTI-277 induced an enrichment in the G2-M phase of the cell cycle. Although FTI-277, GGTI-298, and compactin inhibited A549 cell growth, only GGTI-298 and compactin induced apoptosis as demonstrated by four criteria: 4',6-diamidine-2-phenylindoledihydrochloride staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, DNA fragmentation assay, and flow cytometry. Furthermore, the involvement of geranylgeranylated proteins in apoptotic pathways was confirmed by demonstrating that geranylgeraniol was able to block the ability of compactin to induce apoptosis. These results suggest that protein geranylgeranylation is critical for the control of programmed cell death and that, in A549 cells, farnesylated and geranylgeranylated proteins are involved in G2-M and G0-G1, respectively.

Topics: Adenocarcinoma; Alkyl and Aryl Transferases; Apoptosis; Benzamides; Cell Division; Enzyme Inhibitors; G1 Phase; G2 Phase; Humans; Lung Neoplasms; Methionine; Mitosis; Resting Phase, Cell Cycle; Transferases; Tumor Cells, Cultured