Sodium valproate affects the expression of p16INK4a and p21WAFI/Cip1 cyclin­dependent kinase inhibitors in HeLa cells.

p16INK4a and p21WAF1/Cip1 are cyclin-dependent kinase inhibitors involved in cell cycle control, which can function as oncogenes or tumor suppressors, depending on the context of various extracellular and intracellular signals, and cell type. In human papillomavirus-induced cervical cancer, p16 INK4a shows oncogenic activity and functions as a diagnostic marker of cervical neoplasia, whereas p21 WAF1/Cip1 acts as a tumor suppressor and its downregulation is associated with the progression of malignant transformation. Several histone deacetylase (HDAC) inhibitors promote the positive and negative regulation of a number of genes, including p16 INK4a and p21 WAF1/Cip1; however, the effects of sodium valproate (VPA) on these genes and on the proteins they encode remain uncertain in HeLa cervical cancer cells. In the present study, these effects were investigated in HeLa cells treated with 0.5 or 2 mM VPA for 24 h, using reverse transcription-quantitative PCR, confocal microscopy and western blotting. The results revealed a decrease in the mRNA expression levels of p16 INK4a and a tendency for p16INK4a protein abundance to decrease in the presence of 2 mM VPA. By contrast, an increase in the protein expression levels of p21WAF1/Cip1 was detected in the presence of 0.5 and 2 mM VPA. Furthermore, VPA was confirmed to inhibit HDAC activity and induce global hyperacetylation of histone H3. Notably, VPA was shown to suppress p16 INK4a, a biomarker gene of cervical carcinoma, and to increase the abundance of the tumor suppressor protein p21WAF1/Cip1, thus contributing to the basic knowledge regarding the antitumorigenic potential of VPA. Exploration of epigenetic changes associated with the promoters of p16 INK4a and p21 WAF1/Cip1, such as histone H3 methylation, may provide further information and improve the understanding of these findings.

Characterization of oncogene suppressor marker expression in patients with submucosal gastric carcinoma.

The aim of the present study was to determine the clinical significance of p53 and p21ras p21wafl, p27kip1 and p16ink4a expression in cases of early gastric cancer. A total of 81 patients who had undergone gastrectomy with D2 lymphadenectomy between 1971 and 2004 were retrospectively investigated. The immunohistochemical expression of p21ras, p53, p21waf1/cip1, p27kip1 and p16ink4a in the tissues was evaluated. In normal, metaplastic and tumoral mucosa, p53 was positive in 53, 87.3, and 87.1% of the cases, respectively. In the same tissues, p21ras was positivE in 85.3, 86 and 96.8%, respectively. Positivity FOR p16ink4a was DETECTED IN 46.3, 91.1 and 86% OF THE CASES, respectively, WHEREAS p27kip1 WAS positiVE IN 60, 94.7 and 95.3%, and p21wafl/cip1 WAS positivE IN 32.4, 72.7 and 71.4% OF THE CASES, respectively. All THE tumors WERE positive for p53. Tumors with lymph node invasion presented WITH OVERexpression (+4) of p53 in 47% of the cases VS. 17% OF patients who DID not HAVE lymph node involvement. THEREFORE, higher expression of p53, p21ras and p21wafl/cip1 IN the tumor exhibited a statistically significant association with lymph node involvement.

Atmospheric particulate matter (PM10) exposure-induced cell cycle arrest and apoptosis evasion through STAT3 activation via PKCζ and Src kinases in lung cells.

Atmospheric particulate matter with aerodynamic diameter ≤10 µm (PM10) is a risk factor for the development of lung cancer, but cellular pathways are not completely understood. STAT3 is a p21(Waf1/Cip1) transcription factor and is associated with proliferation and cell survival and is upregulated in lung cancer. PM10 exposure induces p21(Waf1/Cip1) expression, which could be related to STAT3 activation. The aims of this work were to investigate whether STAT3 was activated on lung epithelial cells after PM10 exposure and to determine whether or not STAT3 could have an impact on cell cycle distribution and cell survival. Our results showed that PM10 induced STAT3 activation through Src and PKCζ kinases, and it is partially responsible for the p21(Waf1/Cip1) induction that was also observed. Moreover, PM10 induced G1-G0 cell cycle arrest. The inhibition of STAT3 phosphorylation prevented cell cycle arrest and triggered apoptosis. These results suggest that PM10 exposure might activate a survival pathway related to STAT3 activation, similar to what has been described as part of the immune system and apoptosis evasion during tumor promotion and development.

Cell-cycle analysis and apoptosis-associated proteins in cervical lesions of Brazilian women.

AIM: The aim of the present study was to detect the relative expressions of p53, p21(Waf1/Cip1), p27(Kip1) Bcl-2 and cleaved caspase-3 in cervical lesion samples from Brazilian women by immunohistochemistry. MATERIALS AND METHODS: A total of 230 cervical biopsies in paraffin-embedded blocks were studied: 43 were invasive squamous cell carcinomas (SCC), 52 carcinomas in situ/cervical intraepithelial neoplasias III (CIN III), 54 cervical intraepithelial neoplasias II (CIN II), 51 cervical intraepithelial neoplasias I (CIN I) and 30 non-neoplastic lesions (NN) with benign cellular changes. RESULTS: Significant differences were observed in the p53 expression between the different groups: NN and CIN I (p=0.010); NN and CIN II (p<0.00001); CIN II and CIN III (p=0.02); CIN II and CIS (p=0.0220); CIN II and CEC (p=0.010). Regarding p21(WAF1/Cip1), significant differences were observed between NN and CEC (p=0.001); CIN I and CEC (p=0.001); CIN II and CIN III (p=0,001); CIN II and CIS (p=0.0004) and CIN II and CEC (p<0.0001). For p27(Kip1), significant differences were observed between NN and CIN I (p<0.00001); NN and CIN II (p<0.00001); NN and CIS (p=0.038); CIN I and CIN III (p=0.001); CIN I and CIS (p=0.009); CIN I and CEC (p=0.0001); CIN II and CIN III (p=0.0003); CIN II and CIS (p=0.002); CIN II and CEC (p< 0.00001). Bcl-2 and caspase-3 did not show remarkable differences between groups. CONCLUSION: p53, p21(WAF1/CIP1), p27(KIP1) appear to be involved in the course of carcinogenesis. Rare expression of Bcl-2 and cleaved caspase-3 suggests that these proteins probably do not participate in cervical apoptosis.

Vaccinia virus regulates expression of p21WAF1/Cip1 in A431 cells

In this paper, we provide evidence that both the mRNA and protein levels of the cyclin-dependent kinase (CDK) inhibitor p21WAF1/CDK-interacting protein 1 (Cip1) increase upon infection of A431 cells with Vaccinia virus (VACV). In addition, the VACV growth factor (VGF) seems to be required for the gene expression because infection carried out with the mutant virus VACV-VGF- revealed that this strain was unable to stimulate its transcription. Our findings are also consistent with the notion that the VGF-mediated change in p21WAF1/Cip1 expression is dependent on tyrosine kinase pathway(s) and is partially dependent on mitogen-activated protein kinase/extracellular-signal regulated kinase 1/2. We believe that these pathways are biologically significant because VACV replication and dissemination was drastically affected when the infection was carried out in the presence of the relevant pharmacological inhibitors.