Transfection of HCC lines with wild-type p53 and a reporter with the promoter from the p53-responsive gene WAF1/p21 resulted in a high level of expression, as expected.
Our results also emphasize the chemotherapeutic potential of p21(waf1/cip1) inhibitors, particularly in the HBV-X infected hepatoma which lacks functional p53.
The results showed that p53 over-expression is a reliable marker for mutational modulation of p53 function. p53 was negatively correlated with p21/WAF1 in hepatitis B virus-related HCC (p=0.024, r=-0.432).
These effects were accompanied by downregulation of proteins involved in anti-apoptosis (Bcl-xL, XIAP or c-IAP2) and cell-cycle progression (cyclin D1), and induction of proteins involved in pro-apoptosis (Bax) and cell-cycle retardation (p21Waf1/Cip1), although the degree of changes by DHMEQ was different in each hepatoma cell type.
In this study, we first demonstrated that TF (5-30 microM) induced apoptosis in several types of human cancer cell lines including human hepatoma (Hep G2), colorectal cancer (COLO 205), and fibroblast (CCD 922SK) cells for 24 h. The cellular responses to TF-induced apoptosis were demonstrated to be associated with the p53-signaling pathway, including induction of p53, p21/Cip1, p27/Kip1, bax protein expression and inhibition of bcl-2 protein expression.
To elucidate new regulatory mechanisms for heptocarcinogenesis, we investigated the regulation of p21, a cyclin-dependent kinase (CDK) inhibitor encoded by CDKN1A, in HCC.
CONCLUSIONS We found that JUN, EGR1, MYC, and CDKN1A might be used as diagnostic and therapeutic molecular biomarkers and broaden our understanding of the molecular mechanisms of HCC.
These findings raise the potential that forced upregulation of p21(WAF1/CIP1) in hepatocellular carcinoma (HCC) may reduce the doses of cisplatin to achieve similar responses and suggest the possible use of p21(WAF1/CIP1) in HCC treatment.
The positive rate of HBcAg expression in cancerous tissues of 40 HCCs was 20.0%, which was also lower than that in para-cancerous and adjacent normal liver tissues (chi2 = 9.482, P < 0.01; chi2 = 14.645, P < 0.01). p21 protein deletion rate in cancerous tissues of 40 HCCs was 27.5%, which was higher than that in para-cancerous and adjacent normal liver tissues (chi2 = 7.439, P < 0.01; chi2 = 11.174, P < 0.01). p21 protein deletion correlated remarkably with the pathological grade of HCC (chi2 = 0.072, P < 0.05).
Pharmacological or transcriptional inhibition of both HDAC1 and 2 leads to cell cycle blockage and apoptosis via p21<sup>Waf1/Cip1</sup> and p19<sup>INK4d</sup> upregulation in hepatocellular carcinoma.
We reported here that overexpression of integrin beta1 imposed a growth inhibitory effect on the hepatocellular carcinoma cell line SMMC-7721, and this phenomenon was mainly attributed to the cyclin-dependent kinase inhibitor p21(CIP1).
This study provides important evidence for inhibition of hepatocellular carcinoma (HCC) growth by 15-PGDH through the 15-keto-prostaglandin E2 (15-keto-PGE2)/peroxisome proliferator-activated receptor-γ (PPARγ)/p21(WAF1/Cip1) signaling pathway.
The results demonstrated that combined administration of p21(WAF-1) and GM-CSF could remarkably inhibit the growth of subcutaneously transplanted hepatoma Hepa cells, and significantly increase the survival rate of tumor-bearing mice.
These results suggest that: (1) different modes of p21(WAF1/CIP1) regulation are involved in HCCs differing in their hepatitis viral infection status, and p21(WAF1/CIP1) expression appears to be predominantly related to altered p53 in HCV-related HCCs; (2) disruption of the p53-p21(WAF1/CIP1) cell-cycle-regulating pathway may contribute to malignant progression of HCC.
Even though p21 generally functions as a tumor suppressor, paradoxically many cancers, including HCC, are known to express elevated levels of p21 that correlate with poor prognosis.
The results showed that p53 over-expression is a reliable marker for mutational modulation of p53 function. p53 was negatively correlated with p21/WAF1 in hepatitis B virus-related HCC (p=0.024, r=-0.432).
The results revealed that 1,25(OH)2D3 treatment reduced the expression of HDAC2 and increased the expression of p21(WAF1/Cip1), in a dose-dependent manner, resulting in the reduction of HCC growth.