The impact of ^(60)Co γ-ray on cycles to Hep-2 human laryngeal cancer cell in the condition of hypoxia

Objective： The aim of the study was to investigate the impact of 60Co y-ray on apoptosis, cell cycles and the expression of protein hypoxia-inducible factor-1α （HIF-1α） to Hep-2 cell line in the conditions of normoxia and hypoxia. Methods： Hep-2 cell were divided into 2 groups： group A （normoxia） and group B （hypoxia）. All of the ceils were exposed to y-ray with dosage being 0, 1, 3, 5, 10, 20, and 40 Gy. Flow cytometry was used to measure the protein level of HIF-1α and to detect apoptosis and cell cycles. The protein level of HIF-1α was also determined by immunohistochemistry and Western blotting. Results： The protein level of HIF-1α in group B was significantly higher than that in group A. In group A, low doses （1-5 Gy） of y-ray had caused G0/G1 cell cycle arrest and high doses （10-40 Gy） had caused G2/M cell cycle arrest. In group B, without exposure of y-ray （0 Gy） had caused G0/G1 cell cycle arrest, all of the different dosage of y-ray could cause G2/M cell cycle arrest. The curve of apoptosis rate in group A was a parabola, the apoptotic rate was related to the dosage of y-ray in a dosage dependent manner. The peak was at the point of 5 Gy. The apoptosis rate in group A was significantly higher than that in group B. Conclusion： Different doses of y-ray could cause different cell cycles arrest then make different impact on apoptosis to Hep-2 ceil. The lower apoptosis rate in condition of hypoxia maybe has a relationship with G2/M cell cycle arrest. Up-regulated HIF-1α protein may be one of the reasons for G2/M cell cycle arrest.

Cellular adaptation to hypoxia and p53 transcription regulation

Tumor suppressor p53 is the most frequently mutated gene in human tumors. Meanwhile, under stress conditions, p53 also acts as a transcription factor, regulating the expression of a series of target genes to maintain the integrity of genome. The target genes of p53 can be classified into genes regulating cell cycle arrest, genes involved in apoptosis, and genes inhibiting angiogenesis, p53 protein contains a transactivation domain, a sequence-specific DNA binding domain, a tetramerization domain, a non-specific DNA binding domain that recognizes damaged DNA, and a later identified proline-rich domain. Under stress, p53 proteins accumulate and are activated through two mechanisms. One, involving ataxia telangiectasia-mutated protein （ATM）, is that the interaction between p53 and its down-regulation factor murine double minute 2 （MDM2） decreases, leading to p53 phosphorylation on Serl 5, as determined by the post-translational mechanism; the other holds that p53 increases and is activated through the binding of ribosomal protein L26 （RPL26） or nucleolin to p53 mRNA 5＇ untranslated region （UTR）, regulating p53 translation. Under hypoxia, p53 decreases transactivation and increases transrepression. The mutations outside the DNA binding domain of p53 also contribute to tumor progress, so further studies on p53 should also be focused on this direction. The subter- ranean blind mole rat Spalax in Israel is a good model for hypoxia-adaptation. The p53 of Spalax mutated in residue 172 and residue 207 from arginine to lysine, conferring it the ability to survive hypoxic conditions. This model indicates that p53 acts as a master gene of diversity formation during evolution.

Role of reactive oxygen species in the antiproliferative effects of metavanadate on human prostate cancer DU145 cells

In the present study, the effects of metavanadate on the human prostate cancer cell line DU145 and the underlying mechanism were investigated. The results showed that metavanadate can cause cell cycle arrest at G2/M phase which was evidenced by cell cycle analysis and the increased phosphorylation of Cdc2 at its inactive Tyr-15 site. In addition, the results showed that metavanadate can induce reactive oxygen species （ROS） elevation and decrease the level of Cdc25C. This process can be rescued by an antioxidant, N-acetyl cysteine. In conclusion, the results demonstrate that metavanadate can inhibit cell proliferation via cell cycle arrest at G2/M phase in DU145 ceils. Metavanadate-induced ROS formation may play an important role in this process by mediating the degradation of Cdc25C.

Novel treatment options for portal hypertension

Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications,such as variceal bleeding,ascites or hepatic encephalopathy.As such,clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis.At present,non-selective bblockers,vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia.In contrast,safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue.In recent years,several preclinical and clinical trials have focused on this latter component and other therapeutic avenues.In this review,we highlight novel data in this context and address potentially interesting therapeutic options for the future.