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Capsaicin is the major pungent ingredient in red peppers which is world widely consumed. Except its potent pain relieving efficacy as reported, capsaicin also exerted its antitumor activity in several tumor models. Here, we reported that capsaicin had a profound anti-proliferative effect on human colon cancer cells via inducing cell cycle G0/G1 phase arrest and apoptosis, which was associated with an increase of p21, Bax and cleaved PARP. The underlying mechanism of capsaicin's antitumor potency was mainly attributed to the stabilization and activation of p53. Capsaicin substantially prolonged the half-life of p53 and significantly elevated the transcriptional activity of p53. Through suppressing the interaction between p53 and MDM2, MDM2-mediated p53 ubiquitination was remarkably decreased after capsaicin treatment, which resulted in the stabilization and accumulation of p53. The results of p53-shRNA experiment further demonstrated that p53 knockdown severely impaired the sensitivity of tested cells to capsaicin, G0/G1 phase arrest and the apoptosis induced by capsaicin in p53-knockdown cells was also dramatically decreased, implicating the important role of p53 played in capsaicin's antitumor activity. In summary, our data suggested that capsaicin, or a related analogue, may have a role in the management of human colon cancer.

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A continuous fermentation process has been developed in Pichia pastoris (P. pastoris) with the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter in order to produce large quantities of recombinant human chitinase (rh-chitinase) for preclinical studies as a potential high-dose antifungal drug. Expression levels of about 200 to 400 mg/L have been demonstrated in fed-batch fermentations using strains with either the traditional methanol-inducible or the constitutive GAP promoter. Proteolytic degradation of the enzyme was typically seen in fed-batch fermentations. Continuous production of the enzyme by P. pastoris with the GAP promoter was demonstrated in a 1.5-L working volume fermentor using either glucose or glycerol as the carbon source. The fermentation could be extended for >1 month with a steady-state protein concentration of approximately 300 mg/L. Cell densities were >400 g/L wet cell weight (WCW) (approximately 100 g/L dry cell weight [DCW]) at a dilution rate (D) of 0.83 day(-1) or 1.2 volume exchanges per day (VVD). No proteolytic degradation of the enzyme was seen in the continuous fermentation mode.

Cardiomyocyte death is a major event of myocardial infarction. Previously, we and others have shown that E3 ligase-mediated protein turnover plays a critical role in cardiac injury. In this study, we sought to determine the role of a newly identified E3 ligase, neuregulin receptor degradation protein-1 (Nrdp1), on cardiac ischemia/reperfusion (I/R) injury. I/R injury markedly upregulated Nrdp1 expression in heart tissue. To elucidate the role of Nrdp1 in I/R-induced cardiac injury, neonatal cardiomyocytes were infected with adenoviral constructs expressing wild-type, dominant-negative Nrdp1 genes. Increased Nrdp1 expression enhanced I/R-induced cardiomyocyte apoptosis and inflammation as compared with the green fluorescent protein (GFP) control; these effects were attenuated by overexpression of a dominant-negative Nrdp1 (C34S/H36Q). Furthermore, cardiac-specific Nrdp1 overexpression in vivo in mouse significantly increased infarct size, the number of TUNEL-positive nuclei and inflammatory cells, as well as mortality, as compared with wild-type mice after I/R injury. The mechanisms underlying these effects were associated with the downregulation of an Nrdp1 substrate, ErbB3, accompanied by suppression of its downstream targets AKT, ERK1/2, and activation of p38 and JNK1/2. Together, these results provide evidence for an important role for Nrdp1 in regulating I/R-induced cardiac injury. Nrdp1 may constitute a new therapeutic target for ameliorating the I/R-induced cardiac injury.

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