Studies on the relationship of PDCD 4 with the invasion of astrocytic gliomas / 重庆医学

Objective To investigate the relationship of programmed cell death 4(PDCD4) with the invasion of astrocytic glio-mas .Methods Using the immunohistochemical method to detect the expression of PDCD4 in astrocytic gliomas in different grades . Measuring the peritumoral low-density area on MRI scan ,then compared with the results of immunohistochemical expression .Re-sults The downregulation of PDCD4 was with the increasing of the malignant grade of astrocytic gliomas .The tumor grade malig-nancy was positively correlated with the grade of the peritumoral low-density area on MRI scan(P<0 .05) ,while the expression of PDCD4 was negatively correlated with the grade of astrocytic gliomas (P<0 .01) .Conclusion PDCD4 might serve as one of the in-dicators of invasion and malignant phenotype for astrocytic gliomas .

GHRP-6 induces CREB phosphorylation and growth hormone secretion via a protein kinase Csigma-dependent pathway in GH3 cells / 华中科技大学学报（医学）（英德文版）

This study examined the effect of GHRP-6, a known GHSs receptor agonist, on the phosphorylation of cAMP-responsive element-binding protein (CREB) and the underly mechanism. GH3 cells were cultured and subjected to different treatments as follows: GHRP-6, GHRP-6 plus GHRH, phorbol ester (PMA), an activator of PKC, alone or in combination with GHRP-6, Gö6983, a general inhibitor of PKCs, in the presence or absence of GHRP-6, rottlerin, an inhibitor of PKCs, alone or plus GHRP-6. The cells were transiently transfected with PKCsigma-specific siRNA and then treated with GHRP-6. GH level was measured by enzyme-linked immunosorbent assay (ELISA). The expression of phosphor-CREB, PKCsigma, PKCtheta and phosphor-PKCsigma was determined by Western blotting. The results showed that GHRP-6 stimulated GH secretion in both time- and dose-dependent manners and enhanced the effect of GHRH on GH secretion. GHRP-6 was also found to induce CREB phosphorylation. Moreover, GH secretion was enhanced by the PKC activator PMA and reduced by the PKC inhibitors (Gö6983, rottlerin) and knockdown of PKCsigma. PKCsigma could be activated by GHRP-6. It is concluded that PKC, especially PKCsigma, mediates CREB phosphorylation and GHRP-6-induced GH secretion.