kcc-009 and Lung-Neoplasms

BACKGROUND The expression of transglutaminase 2 (TG2) is correlated to DNA damage repair and apoptosis through the p53 pathway. The present study aimed to investigate the potential radiosensitization effect and possible mechanisms of the TG2 inhibitor KCC009 in lung cancer in vitro. MATERIAL AND METHODS A single hit multi-target model was used to plot survival curves and to calculate the sensitizing enhancement ratios in lung cancer wild-type or mutant p53 of H1299 cells. We performed analyses for changes of cell cycling and apoptotic responses of cells; Western blot analysis and real-time SYBR Green PCR assay were used to determine the changes of mRNA/protein expressions; ELISA assay was used for examination of cytochrome c release in cytoplasm. RESULTS Our results showed that KCC009 induced radiosensitization in both H1299/WT-p53 and H1299/M175H-p53 cells. KCC009+IR induced G0/G1 arrest in H1299/WT cells and G2/M arrest in H1299/M175H-p53 cells. KCC009+IR also induced apoptosis in both cell lines. In addition, KCC009+IR decreased the TG2 expression, and increased the p53 expression in H1299/WT cells but not in H1299/M175H-p53 cells. KCC009+IR also increased the expression of p21, Bax, p-caspase-3, and decreased Bcl-2 and CyclinD expression in H1299/WT cells. While KCC009+IR induced phosphorylation of caspase-3 and increase Cyt-C level in the cytoplasm of, and decreased CyclinB, Bcl-2 expression in H1299/M175H-p53 cells, we noticed that Cyt-C level in the nucleus decreased in the H1299/WT cells. CONCLUSIONS KCC009, a TG2 inhibitor, exhibits potent radiosensitization effects in human lung cancer cells expressing wild-type or mutant p53 with different mechanisms.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Clone Cells; Enzyme Inhibitors; GTP-Binding Proteins; Humans; Isoxazoles; Lung Neoplasms; Protein Glutamine gamma Glutamyltransferase 2; Radiation-Sensitizing Agents; Radiation, Ionizing; Transglutaminases; Tumor Suppressor Protein p53

Tissue transglutaminase (TG2) is implicated in cellular processes such as apoptosis and cell migration. Its acyl transferase activity cross-links certain proteins, among them transcription factors were described. We show here that the TG2 inhibitor KCC009 reversed resistance to tumor necrosis factor-related apoptosis-inducing factor (TRAIL) in lung cancer cells. Sensitization required upregulation of death receptor 5 (DR5) but not of death receptor 4. Upregulation of DR5 involved the first intron of the DR5 gene albeit it was independent from p53 and nuclear factor kappa B. In conclusion, inhibition of tissue transglutaminase provides an interesting strategy for sensitization to TRAIL-induced apoptosis in p53-deficient lung cancer cells.

Topics: Apoptosis; Cell Line, Tumor; Flow Cytometry; GTP-Binding Proteins; Humans; Immunoblotting; Introns; Isoxazoles; Lung Neoplasms; Promoter Regions, Genetic; Protein Glutamine gamma Glutamyltransferase 2; Receptors, TNF-Related Apoptosis-Inducing Ligand; Receptors, Tumor Necrosis Factor; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering; TNF-Related Apoptosis-Inducing Ligand; Transglutaminases; Up-Regulation