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Growth arrest DNA damage-inducible gene 45 gamma expression as a prognostic and predictive biomarker in hepatocellular carcinoma.

ABSTRACT: Growth arrest DNA damage-inducible gene 45 (GADD45) family proteins play a crucial role in regulating cellular stress responses and apoptosis. The present study explored the prognostic and predictive role of GADD45? in hepatocellular carcinoma (HCC) treatment. GADD45? expression in HCC cells was examined using quantitative reverse transcription-PCR (qRT-PCR) and Western blotting. The control of GADD45? transcription was examined using a luciferase reporter assay and chromatin immunoprecipitation. The in vivo induction of GADD45? was performed using adenoviral transfer. The expression of GADD45? in HCC tumor tissues from patients who had undergone curative resection was measured using qRT-PCR. Sorafenib induced expression of GADD45? mRNA and protein, independent of its RAF kinase inhibitor activity. GADD45? induction was more prominent in sorafenib-sensitive HCC cells (Huh-7 and HepG2, IC50 6-7 ?M) than in sorafenib-resistant HCC cells (Hep3B, Huh-7R, and HepG2R, IC50 12-15 ?M). Overexpression of GADD45? reversed sorafenib resistance in vitro and in vivo, whereas GADD45? expression knockdown by using siRNA partially abrogated the proapoptotic effects of sorafenib on sorafenib-sensitive cells. Overexpression of survivin in HCC cells abolished the antitumor enhancement between GADD45? overexpression and sorafenib treatment, suggesting that survivin is a crucial mediator of antitumor effects of GADD45?. GADD45? expression decreased in tumors from patients with HCC who had undergone curative surgery, and low GADD45? expression was an independent prognostic factor for poor survival, in addition to old age and vascular invasion. The preceding data indicate that GADD45? suppression is a poor prognostic factor in patients with HCC and may help predict sorafenib efficacy in HCC.

SUBMITTER: Ou DL

PROVIDER: S-EPMC4695037 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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Growth arrest DNA damage-inducible gene 45 gamma expression as a prognostic and predictive biomarker in hepatocellular carcinoma.

Ou Da-Liang DL Shyue Song-Kun SK Lin Liang-In LI Feng Zi-Rui ZR Liou Jun-Yang JY Fan Hsiang-Hsuan HH Lee Bin-Shyun BS Hsu Chiun C Cheng Ann-Lii AL

Oncotarget 20150901 29

Growth arrest DNA damage-inducible gene 45 (GADD45) family proteins play a crucial role in regulating cellular stress responses and apoptosis. The present study explored the prognostic and predictive role of GADD45γ in hepatocellular carcinoma (HCC) treatment. GADD45γ expression in HCC cells was examined using quantitative reverse transcription-PCR (qRT-PCR) and Western blotting. The control of GADD45γ transcription was examined using a luciferase reporter assay and chromatin immunoprecipitation ...[more]

PMID: 26172295

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Project description:Growth arrest DNA damage-inducible gene 45 beta (GADD45beta) has been known to regulate cell growth, apoptotic cell death, and cellular response to DNA damage. Down-regulation of GADD45beta has been verified to be specific in hepatocellular cancer (HCC) and consistent with the p53 mutant, and degree of malignancy of HCC. This observation was further confirmed by eight HCC cell lines and paired human normal and HCC tumor tissues by Northern blot and immunohistochemistry. To better understand the transcription regulation, we cloned and characterized the active promoter region of GADD45beta in luciferase-expressing vector. Using the luciferase assay, three nuclear factor-kappaB binding sites, one E2F-1 binding site, and one putative inhibition region were identified in the proximal promoter of GADD45beta from -865/+6. Of interest, no marked putative binding sites could be identified in the inhibition region between -520/-470, which corresponds to CpG-rich region. The demethylating agent 5-Aza-dC was used and demonstrated restoration of the GADD45beta expression in HepG2 in a dose-dependent manner. The methylation status in the promoter was further examined in one normal liver cell, eight HCC cell lines, eight HCC tissues, and five corresponding nonneoplastic liver tissues. Methylation-specific polymerase chain reaction and sequencing of the sodium bisulfite-treated DNA from HCC cell lines and HCC samples revealed a high percentage of hypermethylation of the CpG islands. Comparatively, the five nonneoplastic correspondent liver tissues demonstrated very low levels of methylation. To further understand the functional role of GADD45beta under-expression in HCC the GADD45beta cDNA constructed plasmid was transfected into HepG2 (p53 WT) and Hep3B (p53 null) cells. The transforming growth factor-beta was assayed by enzyme-linked immunosorbent assay, which revealed a decrease to 40% in transfectant of HepG2, but no significant change in Hep3B transfectant. Whereas, Hep3B co-transfected with p53 and GADD45beta demonstrated significantly reduced transforming growth factor-beta. The colony formation was further examined and revealed a decrease in HepG2-GADD45beta transfectant and Hep3B-p53/GADD45beta co-transfectant. These findings suggested that methylation might play a crucial role in the epigenetic regulation of GADD45beta in hepatocyte transformation that may be directed by p53 status. Thus, our results provided a deeper understanding of the molecular mechanism of GADD45beta down-regulation in HCC.

Project description:In this study, we describe the growth arrest DNA damage-inducible gene 45beta (GADD45beta), whose expression was significantly down-regulated in the hepatocellular carcinoma (HCC) microarray study and confirmed by Northern blot analysis. The results suggested that expression of GADD45beta was decreased in human liver cancer cell lines HepG2 and Hep3B, but not in normal human embryonic liver cell line CL-48 or normal liver tissue. Histochemistry study and real-time PCR further confirmed that GADD45beta staining in HCC was significantly decreased when compared to surrounding non-neoplastic liver tissue. In further studies of multiple human cancer tissues, GADD45beta strongly stained tissues such as colon cancer, breast cancer, prostate cancer, squamous cell cancer, lymphoma, and leiomyosarcoma, suggesting that the decreased expression of GADD45beta is specific to HCC. Eighty-five cases of primary HCC were further examined by immunohistochemistry and statistical analyses demonstrated that HCC scored lower than matched non-neoplastic liver tissues consistently and significantly. No staining occurred in 12.94% of HCC cases (score = 0, n = 11); 42.35% had weak staining (score = 1, n = 36); 27.06% had moderate staining (score = 2, n = 23); and 17.65% had staining as strong as normal tissue (score = 3, n = 15). Overall, surrounding non-neoplastic liver tissue was highly positive for GADD45beta compared to adjacent neoplastic liver tissues (P < 0.01). We further observed that down-regulation of GADD45beta expression was strongly correlated with differentiation (P < 0.01) and high nuclear grade (P < 0.01). Moreover, we found that expression of GADD45beta was inversely correlated to the presence of mutant p53 in HCC tissue (P < 0.05). Thus, the results of our study suggest that GADD45beta, which is down-regulated in most cases of HCC, remains an ideal candidate for development as a molecular marker in the diagnosis of HCC and as a potential therapeutic target.

Dataset Information

Growth arrest DNA damage-inducible gene 45 gamma expression as a prognostic and predictive biomarker in hepatocellular carcinoma.

Publications

Growth arrest DNA damage-inducible gene 45 gamma expression as a prognostic and predictive biomarker in hepatocellular carcinoma.

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