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Abstract: Background and aim: The krü;ppel-like transcription factor KLF6 is a novel tumor-suppressor gene. It was inactivated in human prostate cancer and other tumors tissue, as the result of frequent mutation and loss of heterozygosity (LOH). However, there is no data reporting the levels of KLF6 both mRNA and protein in hepatocellular carcinomas (HCCs). We therefore detected mutations and expression of KLF6 in HCC tissues and further observed the effect of it on cell growth in HCC cell lines. Methods: We analyzed the exon-2 of KLF6 gene by direct DNA sequencing, and detected the expression of KLF6 by RT-PCR and Western blot in 23 HCC tissues and corresponding nontumorous tissues. Loss of growth suppressive effect of the HCC-derived KLF6 mutant was characterized by in vitro growth curves plotted, flow cytometry and Western blotting. Results: KLF6 mutations were found in 2 of 23 HCC tissues and one of mutations was missense. Expression of KLF6 mRNA or protein was down-regulated in 8 (34.7%) or 9 (39.1%) of 23 HCC tissues. Wild-type KLF6 (wtKLF6) inhibited cellular proliferation and prolonged G1-S transition by inducing the expression of p21WAF1 following stable transfection into cultured HepG2 cells, but tumor-derived KLF6 mutant (mKLF6) had no effects. Conclusion: Our findings suggest that KLF6 may be involved in pathogenesis of HCC.

[1] Benzeno, S., Narla, G., Allina, J., Cheng, G.Z., Reeves, H.L., Banck, M.S., Odin, J.A., Didhl, J.A., Germain, D., Freedman, S.L., 2004. Cyclin dependent kinase inhibition by the KLF6 tumor suppressor protein through interaction with cyclin D1. Cancer Res., 64(11):3885-3891.

[2] Boyault, S., Herault, A., Balabaud, C., Zucman-Rossi, J., 2005. Absence of KLF6 gene mutation in 71 hepatocellular carcinomas. Hepatology, 41(3):681-682.

[3] Bruix, J., Boix, L., Sala, M., Llovet, J.M., 2004. Focus on hepatocellular carcinoma. Cancer Cell, 5(3):215-219.

[4] Chen, H.K., Liu, X.Q., Lin, J., Chen, T.Y., Feng, Q.S., Zeng, Y.X., 2002. Mutation analysis of KLF6 gene in human nasopharyngeal carcinomas. Ai Zheng, 21(10):1047-1050 (in Chinese).

[5] Feitelson, M.A., Sun, B., Satiroglu Tufan, N.L., Liu, J., Pan, J.B., Lian, Z.R., 2002. Genetic mechanisms of hepatocarcinogenesis. Oncogene, 21(16):2593-2604.

[6] Hui, A.M., Sakamoto, M., Kanai, Y., Ino, Y., Gotoh, M., Yokota, J., Hirohashi, S.L., 1996. Inactivation of p16INK4 in hepatocellular carcinoma. Hepatology, 24(3):575-579.

[7] Ito, G., Uchiyama, M., Kondo, M.S., Mori, S., Usami, N., Maeda, O., Kawabe, T., Hasegawa, Y., Shimokata, K., Sekido, Y., 2004. Krüppel-like factor 6 (KLF6) is frequently downregulated and induces apoptosis in non-small cell lung cancer cells. Cancer Res., 64(11):3838-3843.

[8] Jeng, Y.M., Hsu, H.C., 2003. KLF6, a putative tumor suppressor gene, is mutated in astrocytic gliomas. Int. J. Cancer, 105(5):625-629.

[9] Kimmelman, A.C., Qiao, R.F., Narla, G., Banno, A., Lau, N., Bos, P.D., Rodriguez, N.N., Liang, B.C., Guha, A., Friedman, S.C., Chan, A.M., 2004. Suppression of glioblastoma tumorigenicity by the Krüppel-like transcription factor KLF6. Oncogene, 23(29):5077-5083.

[10] Köhler, B., Wolter, M., Blaschke, B., Reifenberger, G., 2004. Absence of mutations in the putative tumor suppressor gene KLF6 in glioblastomas and meningiomas. Int. J. Cancer, 111(4):644-645.

[11] Koivisto, P.A., Zhang, X., Sallinen, S.L., Sallinen, S., Helin, H.J., Dong, J.T., van Meir, E.G., Haapasalo, H., Hyytinen, E.R., 2004. Absence of KLF6 gene mutations in human astrocytic tumors and cell lines. Int. J. Cancer, 111(4):642-643.

[12] Kremer-Tal, S., Reeves, H.L., Narla, G., Thung, S.N., Schwartz, M., Difeo, A., Katz, A., Bruix, J., Bioulac-Usage, P., Martignetti, J.A., Friedman, S.C., 2004a. Frequent inactivation of the tumor suppressor Krüppel-like factor 6 (KLF6) in hepatocellular carcinoma. Hepatology, 40(5):1047-1052.

[13] Kremer-Tal, S., Narla, G., Banck, M., Difeo, A.V., 2004b. Significantly decreased expression of the tumor suppressor KLF6 in 85% of HCCs contributes to enhanced growth and reduced differentiation. Hepatology, 40:520A.

[14] Montanini, L., Bissola, L., Finocchiaro, G., 2004. KLF6 is not the major target of chromosome 10p losses in glioblastomas. Int. J. Cancer, 111(4):640-641.

[15] Mühlbauer, K.R., Grone, H.J., Ernst, T.E., Grone, E., Tschata, R., Hergenhahn, M., Hollstein, M., 2003. Analysis of human prostate cancers and cell lines for mutations in the TP53 and KLF6 tumour suppressor genes. Br. J. Cancer, 89(4):687-690.

[16] Narla, G., Heath, K.E., Reeves, H.L., Li, D., Giono, L.E., Kimmelman, A.C., Glucksman, M.J., Narla, J., Eng, F.J., 2001. KLF6, a candidate tumor suppressor gene mutated in prostate cancer. Science, 294(5551):2563-2566.

[17] Narla, G., Difeo, A., Reeves, H.L., Schaid, D.J., Hirshfeld, J., Hod, E., Katz, A., Isaacs, W.B., Hebbring, S., Komiya, A., McDonnell, S.K., Wiley, K.E., 2005. A germline DNA polymorphism enhances alternative splicing of the KLF6 tumor suppressor gene and is associated with increased prostate cancer risk. Cancer Res., 65(4):1213-1222.

[18] Reeves, H.L., Narla, G., Ogunbiyi, O., Haq, A.I., Katz, A., Benzeno, S., Hod, E., Harpaz, N., Goldberg, S., Tal-Kermer, S., Eng, F.J., 2004. Krüppel-like factor 6 (KLF6) is a tumor-suppressor gene frequently inactivated in colorectal cancer. Gastroenterology, 126(4):1090-1103.

[19] Slavin, D.A., Koritschoner, N.P., Prieto, C.C., Lopez-Diaz, F.J., Chatton, B., Bocco, J.L., 2004. A new role for the Krüppel-like transcription factor KLF6 as an inhibitor of c-jun proto-oncoprotein function. Oncogene, 23(50):8196-8205.

[20] Staib, F., Hussain, S.P., Hofseth, L.J., Wang, X., Harris, C.C., 2003. TP53 and liver carcinogenesis. Human Mutation, 21(3):201-216.

[21] Wang, S.P., Chen, X.P., Qiu, F.Z., 2004. A candidate tumor suppressor gene mutated in primary hepatocellular carcinoma: Krüppel-like factor 6. Zhonghua Wai Ke Za Zhi, 42(20):1258-1261 (in Chinese).

[22] Yamashita, K., Upadhyay, S., Osada, M., Hoque, M.O., Xiao, Y., Mori, M., Sato, F., Meltzer, S.J., Sidransky, D., 2002. Pharmacologic unmasking of epigenetically silenced tumor suppressor genes in esophageal squamous cell carcinoma. Cancer Cell, 2(6):485-495.