Knockdown of vps54 aggravates tamoxifen-induced cytotoxicity in fission yeast

Tamoxifen (TAM) is an anticancer drug used to treat estrogen receptor (ER)‒positive breast cancer. However, its ER-independent cytotoxic and antifungal activities have prompted debates on its mechanism of action. To achieve a better understanding of the ER-independent antifungal action mechanisms of TAM, we systematically identified TAM-sensitive genes through microarray screening of the heterozygous gene deletion library in fission yeast (Schizosaccharomyces pombe). Secondary confirmation was followed by a spotting assay, finally yielding 13 TAM-sensitive genes under the drug-induced haploinsufficient condition. For these 13 TAM-sensitive genes, we conducted a comparative analysis of their Gene Ontology (GO) ‘biological process’ terms identified from other genome-wide screenings of the budding yeast deletion library and the MCF7breast cancer cell line. Several TAM-sensitive genes overlapped between the yeast strains and MCF7 in GO terms including ‘cell cycle’ (cdc2, rik1, pas1, and leo1), ‘signaling’ (sck2, oga1, and cki3), and ‘vesicle-mediated transport’ (SPCC126.08c, vps54, sec72, and tvp15), suggesting their roles in the ER-independent cytotoxic effects of TAM. We recently reported that the cki3 gene with the ‘signaling’ GO term was related to the ER-independent antifungal action mechanisms of TAM in yeast. In this study, we report that haploinsufficiency of the essential vps54 gene, which encodes the GARP complex subunit, significantly aggravated TAM sensitivity and led to an enlarged vesicle structure in comparison with the SP286 control strain. These results strongly suggest that the vesicle-mediated transport process might be another action mechanism of the ER-independent antifungal or cytotoxic effects of TAM.

Transactivation of bad by vorinostat-induced acetylated p53 enhances doxorubicin-induced cytotoxicity in cervical cancer cells

Vorinostat (VOR) has been reported to enhance the cytotoxic effects of doxorubicin (DOX) with fewer side effects because of the lower DOX dosage in breast cancer cells. In this study, we investigated the novel mechanism underlying the synergistic cytotoxic effects of VOR and DOX co-treatment in cervical cancer cells HeLa, CaSki and SiHa cells. Co-treatment with VOR and DOX at marginal doses led to the induction of apoptosis through caspase-3 activation, poly (ADP-ribose) polymerase cleavage and DNA micronuclei. Notably, the synergistic growth inhibition induced by the co-treatment was attributed to the upregulation of the pro-apoptotic protein Bad, as the silencing of Bad expression using small interfering RNA (siRNA) abolished the phenomenon. As siRNA against p53 did not result in an increase in acetylated p53 and the consequent upregulation of Bad, the observed Bad upregulation was mediated by acetylated p53. Moreover, a chromatin immunoprecipitation analysis showed that the co-treatment of HeLa cells with VOR and DOX increased the recruitment of acetylated p53 to the bad promoter, with consequent bad transactivation. Conversely, C33A cervical cancer cells containing mutant p53 co-treated with VOR and DOX did not exhibit Bad upregulation, acetylated p53 induction or consequent synergistic growth inhibition. Together, the synergistic growth inhibition of cervical cancer cell lines induced by co-treatment with VOR and DOX can be attributed to the upregulation of Bad, which is induced by acetylated p53. These results show for the first time that the acetylation of p53, rather than histones, is a mechanism for the synergistic growth inhibition induced by VOR and DOX co-treatments.

Evaluation of characteristics on titanium surface treatment for absorption of functional groups / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>In order to bind or fix bioactive materials directly to the surface of a Ti implant, the prior binding process of functional groups (FGs, -COOH and -OH) to the implant surface is necessary. Conventional binding processes are so high-cost and complex, so it is essential to find a simple and effective procedure for Ti-FG binding.</p><p><b>METHODS</b>Various electrolyte compositions and electrochemical processing were adopted in this study to develop a relatively simple and effective Ti-FG binding process. The ability of Ti-FG binding and calcium (Ca)/phosphorous (P) absorption and corrosion resistance were evaluated according to various titanium surface treatment in electrolyte involving -COOH and -OH ion by using X ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM) and potentiodynamic scan method respectively.</p><p><b>RESULTS</b>In cases of -COOH, the anodic oxidation process (AN) showed an effective binding ability between -COOH and Ti surface. On the other hand, in cases of -OH, there were no significant differences in the result between the conditions used. In regard to the absorption of Ca and P on Ti surface, there was a minimal amount of Ca absorbed but no P was absorbed. The anodic oxidation series showed homogenous corrosion, whereas the electrolyte immersion (EL) series showed unstable corrosion. Although EL-OH showed a novel corrosion potential, the EL-COOH series showed good corrosion resistance over the anodic potential range.</p><p><b>CONCLUSIONS</b>The ability of binding between FG and the Ti surface and Ca/P absorption were strongly associated with the surface potential (ζ potential), which was dependent on the pH of the electrolyte. Accordingly, in order to achieve the effective absorption of various FGs on the Ti surface, it is needed to develop the combination process in addition to the electric affinity, relation with the ζ potential.</p>

Effects of Extremely Low Doses of Arginine Vasopressin on the Renal Function in Two-kidney One Clip Goldblatt Hypertensive Rabbit / 대한신장학회잡지

It has been suggested that arginine vasopressin is involved in the acute, but not chronic, regulation of blood pressure. It is still debatable on the role of arginine vasopressin in the development and maintenance of high blood pressure, especially in renal hypertension. This study was performed to examine antidiuretic and renal hemodynamic effects of extremely low doses of arginine vasopressin and the modification of the effects in the early phase of two-kidney one clip Goldblatt hypertensive rabbits. Very low doses(up to 10-20mole/kg/min) of intrarenal arginine vasopressin induced decreases in urine volume, free water clearance, glomerular filteration rate and renal plasma flow(CPAH). The renal effects of arginine vasopressin were dose-dependent. These data indicate that the sensitivity of the kidney to decrease urine volume in response to arginine vasopressin is at least three orders of magnitude higher than previously reported. The renal effects of arginine vasopressin was significantly attenuated by the pretreatment of V2-receptor antagonist. The antidiuretic and renal hemodynamic effects elicited by very low doses of intrarenal arginine vasopressin were suppressed in the contralateral unclipped kidney of two-kidney, one clip Goldblatt hypertensive rabbits. These data suggest that the renal functions can be regulated normally by an extremely low concentration of plasma arginine vasopressin and the regulatory mechanism controlled by the ultralow plasma levels of arginine vasopressin is suppressed in the early phase of two-kidney, one clip Goldblatt hypertension.

Effects of Intrarenal Arterial Infusion of Arginine Vasopressin on the Renal Function and Renin Release in Conscious Rabbits / 대한신장학회잡지

Arginine vasopressin(AVP) released from the posterior pituitary gland is well known to cause an increase in blood pressure, antidiuresis, natriuresis and inhibition of renin secretion. However, the mechanism involved in AVP-induced natriuresis is still unknown. To investigate the mechanism of AVP- induced natriuresis, different doses of AVP were infused into the left renal artery for 10 min and renal function and data were obtained in unanesthetized rabbits. Infusion of different doses of AVP (0.3pg/kg/min-10,000pg/kg/min) caused marked decreases in urine volume, renal blood flow, glomerular filtration rate and free water clearance without changes in blood pressure. Changes in renal function by AVP were not dose-dependent but it took more time for the renal function to recover with increasing doses. Infusion of large doses of AVP(3,000, 10,000pg/kg/min) caused increases in sodium excretion in both kidneys without changes in blood pressure. Infusion of AVP caused a decrease in renin secretion rate. In indomethacin-treated rabbits, changes in urine volume and renal hemodynamics by AVP were markedly accentuated whereas natriuretic effects were attenuated. However, a marked natriuresis caused by AVP in control right kidney still persistently existed. These results suggest that the AVP-induced natriuresis may occur in two-different ways: one is indirect hormonal including prostaglandins and the other is tubular.