Recent advance in the regulation of PTEN's function / 中国药理学通报

The tumor suppressor PTEN is a dual-specificity phosphatase possessing both protein phosphatase and lipid phosphatase activity. PTEN inhibits phosphatidylinositol-3-kinase (PI3-K)/ Akt signaling pathway by dephosphorylating phosphatidylinositol-(3,4,5)-triphosphate at the 3 site. PTEN plays a pivotal role in cell growth, proliferation, migration, and apoptosis. The deregulation of PTEN has been implicated in a variety of human cancers such as prostate, endometrial, and breast cancers. Cellular PTEN's function appears to be regulated by its expression, phosphorylation, oxidation, and membrane binding. This review summarized the current progress in the molecular mechanism of PTEN's function.

Serine/threonine protein kinase Akt and Akt targeting anticancer drug development / 中国药理学通报

Dyregulation of serine/threonine protein kinase Akt/PKB activity is a prominent feature of many human cancers.A large number of studies have demonstrated that Akt plays a key role in mediating cell growth and proliferation,promoting cell migration and invasion,stimulating neoangiogenesis,and protecting from pro-apoptotic stimuli.In view of the highly pleiotropic biologic effects of Akt signaling in multiple aspects of tumor pathophysiology,development of clinically applicable drugs specifically targeting Akt has been the subject of intense research.Up to now,a number of Akt specific inhibitors such as API2,Akt-I-1,Akt-I-2 and DCIEL have been developed and investigated in pre-clinical studies.These compounds have been shown to potently inhibit growth of tumors with aberrantly expressed or activated Akt,therefore,are likely to be developed as promising targeted anticancer drugs.

Differential roles of phosphatidylinositol 3-kinase in mitogen-activated prote in kinase activation by insulin and epidermal growth factor / 中国药理学通报

Aim To investigate the roles of phosphatidylinositol 3 -kinase (PI3K) in the mitogen-activated protein kinase (MAPK) activation by in sulin and epidermal growth factor (EGF). Methods Phosphorylated MAPK, Akt (also termed protein kinase B) and total protein level of MAPK were d etermined by Western blotting using phospho- or non-phospho-state specific an tibodies;the roles of PI3K in these signaling transduction pathways were assess ed by use of PI3K specific inhibitor wortmannin.Results Both in sulin and EGF rapidly stimulated MAPK phosphorylation; wortmannin totally blocke d the MAPK phosphorylation stimulated by insulin, but not by EGF.By contrast, wo rtmannin equally inhibited Akt phosphorylation stimulated by both insulin and EG F. Moreover, wortmannin inhibited insulin-stimulated MAPK phosphorylation in a concentration-dependent manner,and the inability of wortmannin to inhibit EGF -stimulated MAPK phosphorylation was not changed with the use of low concentrat ions of EGF.Conclusion PI3K plays different roles in the MAPK a ctivation induced by insulin and EGF.