Targeting the Hsp90-Cdc37-client protein interaction to disrupt Hsp90 chaperone machinery.

Heat shock protein 90 (Hsp90) is a critical molecular chaperone protein that regulates the folding, maturation, and stability of a wide variety of proteins. In recent years, the development of Hsp90-directed inhibitors has grown rapidly, and many of these inhibitors have entered clinical trials. In parallel, the functional dissection of the Hsp90 chaperone machinery has highlighted the activity disruption of Hsp90 co-chaperone as a potential target. With the roles of Hsp90 co-chaperones being elucidated, cell division cycle 37 (Cdc37), a ubiquitous co-chaperone of Hsp90 that directs the selective client proteins into the Hsp90 chaperone cycle, shows great promise. Moreover, the Hsp90-Cdc37-client interaction contributes to the regulation of cellular response and cellular growth and is more essential to tumor tissues than normal tissues. Herein, we discuss the current understanding of the clients of Hsp90-Cdc37, the interaction of Hsp90-Cdc37-client protein, and the therapeutic possibilities of targeting Hsp90-Cdc37-client protein interaction as a strategy to inhibit Hsp90 chaperone machinery to present new insights on alternative ways of inhibiting Hsp90 chaperone machinery.

A Systematic Review of the Anticancer Properties of Compounds Isolated from Licorice (Gancao).

Licorice (Gancao in Chinese) has been used worldwide as a botanical source in medicine and as a sweetening agent in food products for thousands of years. Triterpene saponins and flavonoids are its main ingredients that exhibit a variety of biological activities, including hepatoprotective, antiulcer, anti-inflammatory, antiviral and anticancer effects among others. This review attempts to summarize the current knowledge on the anticancer properties and mechanisms of the compounds isolated from licorice and obtain new insights for further research and development of licorice. A broad spectrum of in vitro and in vivo studies have recently demonstrated that the mixed extracts and purified compounds from licorice exhibit evident anticancer properties by inhibition of proliferation, induction of cell cycle arrest, apoptosis, autophagy, differentiation, suppression of metastasis, angiogenesis, and sensitization of chemotherapy or radiotherapy. A combined treatment of licorice compounds and clinical chemotherapy drugs remarkably enhances anticancer effects and reduces the side effects of chemotherapeutics. Furthermore, glycyrrhizic acid and glycyrrhetinic acid in licorice have been indicated to present obvious liver-targeting effects in targeted drug delivery systems for hepatocellular carcinoma treatment.

Elusive liver factor that causes pancreatic α cell hyperplasia: A review of literature.

Tumors and cancers of the gastrointestinal tract and pancreas are commonly derived from precursor lesions so that understanding the physiological, cellular, and molecular mechanisms underlying the pathogenesis of precursor lesions is critical for the prevention and treatment of those neoplasms. Pancreatic neuroendocrine tumors (PNETs) can also be derived from precursor lesions. Pancreatic α cell hyperplasia (ACH), a specific and overwhelming increase in the number of α cells, is a precursor lesion leading to PNET pathogenesis. One of the 3 subtypes of ACH, reactive ACH is caused by glucagon signaling disruption and invariably evolves into PNETs. In this article, the existing work on the mechanisms underlying reactive ACH pathogenesis is reviewed. It is clear that the liver secretes a humoral factor regulating α cell numbers but the identity of the liver factor remains elusive. Potential approaches to identify the liver factor are discussed.

Glycyrrhetinic Acid triggers a protective autophagy by activation of extracellular regulated protein kinases in hepatocellular carcinoma cells.

Glycyrrhetinic acid (GA), one of the main constituents of the famous Chinese medicinal herb and food additive licorice (Glycyrrhiza uralensis Fisch), has been indicated to possess potential anticancer effects and is widely utilized in hepatocellular carcinoma (HCC) targeted drug delivery systems (TDDS) due to the highly expressed target binding sites of GA on HCC cells. This study found that GA reduced the cell viability, increased the release of lactate dehydrogenase, and enhanced the expression of Bax, cleaved caspase-3, and LC3-II in HCC cells. The GA-triggered autophagy has been further confirmed by monodansylcadaverine staining as well as transmission electron microscopy analysis. The cell viability was obviously decreased whereas the expression of cleaved caspases was significantly increased when inhibition of autophagy by choloroquine or bafilomycin A1, suggesting that GA triggered a protective autophagy. Extracellular regulated protein kinase (ERK) was activated after treatment with GA in HepG2 cells and pretreatment with U0126 or PD98059, the MEK inhibitors, reversed GA-triggered autophagy as evidenced by decreased expression of LC3-II and formation of autophagosomes, respectively. Furthermore, GA-induced cell death and apoptosis were enhanced after pretreatment with PD98059. This is the first report that GA triggers a protective autophagy in HCC cells via activation of ERK, which might attenuate the anticancer effects of GA or chemotherapeutic drugs loaded with GA-modified TDDS.

Genomics in personalized cancer medicine and its impact on early drug development in China: report from the 6th Annual Meeting of the US Chinese Anti-Cancer Association (USCACA) at the 50th ASCO Annual Meeting.

The 6th Annual Meeting of the United States Chinese Anti-Cancer Association (USCACA) was held in conjunction with the 50th Annual Meeting of American Society of Clinical Oncology (ASCO) on May 30, 2014 in Chicago, Illinois, the United States of America. With a focus on personalized medicine, the conference featured novel approaches to investigate genomic aberrations in cancer cells and innovative clinical trial designs to expedite cancer drug development in biomarker-defined patient populations. A panel discussion further provided in-depth advice on advancing development of personalized cancer medicines in China. The conference also summarized USCACA key initiatives and accomplishments, including two awards designated to recognize young investigators from China for their achievements and to support their training in the United States. As an effort to promote international collaboration, USCACA will team up with Chinese Society of Clinical Oncology (CSCO) to host a joint session on "Breakthrough Cancer Medicines" at the upcoming CSCO Annual Meeting on September 20th, 2014 in Xiamen, China.

DJ-1 mediates the resistance of cancer cells to dihydroartemisinin through reactive oxygen species removal.

Dihydroartemisinin (DHA), one of the main metabolites of artemisinin and its derivatives, presents anti-cancer potential in vitro and in vivo. To explore the mechanisms of resistance toward DHA, a DHA-resistant cell line, HeLa/DHA, was established with a resistance factor of 7.26 in vitro. Upon DHA treatment, apoptotic cells were significantly elicited in parental HeLa cells but minimally induced in HeLa/DHA cells. HeLa/DHA cells also displayed much less sensitivity to DHA-induced tumor suppression in cancer xenograft models than HeLa cells. Intriguingly, DHA-resistant cells did not display a multidrug-resistant phenotype. Based on a proteomic study employing LC-ESI-MS/MS together with pathway analysis, DJ-1 (PARK7) was found to be highly expressed in HeLa/DHA cells. Western blot and immunofluorescence assays confirmed the higher expression of DJ-1 in HeLa/DHA cells than in parental cells in both cell line and xenograft models. DJ-1 is translocated to the mitochondria of HeLa/DHA cells and oxidized, providing DJ-1 with stronger cytoprotection activity. Further study revealed that DJ-1 knockdown in HeLa/DHA cells abolished the observed resistance, whereas overexpression of DJ-1 endowed the parental HeLa cells with resistance toward DHA. Reactive oxygen species (ROS) were also significantly induced by either DHA or hydrogen peroxide in HeLa cells but not in resistant HeLa/DHA cells. When the cells were pretreated with N-acetyl-l-cysteine, the effect of DJ-1 knockdown on sensitizing HeLa/DHA cells to DHA was significantly attenuated. In summary, our study suggests that overexpression and mitochondrial translocation of DJ-1 provides HeLa/DHA cells with resistance to DHA-induced ROS and apoptosis.

Pseudolarix acid B, a new tubulin-binding agent, inhibits angiogenesis by interacting with a novel binding site on tubulin.

Tubulin-binding agents have received considerable interest as potential tumor-selective angiogenesis-targeting drugs. Herein, we report that pseudolarix acid B (PAB), isolated from the traditional Chinese medicinal plant Pseudolarix kaempferi Gordon, is a tubulin-binding agent. We further demonstrate that PAB significantly and dose-dependently inhibits proliferation, migration, and tube formation by human microvessel enthothelial cells. It is noteworthy that PAB eliminated newly formed endothelial tubes and microvessels both in vitro and in vivo. In addition, PAB dramatically arrested the cell cycle at G2/M phase. PAB also induced endothelial cell retraction, intercellular gap formation, and promoted actin stress fiber formation in conjunction with disruption of the tubulin and actin cytoskeletons. All of these effects occurred at noncytotoxic concentrations of PAB. We found that these effects of PAB are attributable to depolymerization of tubulin by direct interaction with a distinct binding site on tubulin compared with those of colchicine and vinblastine. Taken together, these findings show that PAB is a candidate antiangiogenic agent for use in cancer therapy, and they provide proof of principle for targeting this novel binding site on tubulin as a new strategy for treating cancer.

Quercetin, a dietary-derived flavonoid, possesses antiangiogenic potential.

Quercetin, a dietary-derived flavonoid, suppresses tumor growth in vitro and in vivo, and inhibits the activity of tyrosine kinase. The effects of quercetin on the angiogenic process were examined in this study. Quercetin was found to inhibit several important steps of angiogenesis including proliferation, migration, and tube formation of human microvascular dermal endothelial cells in a dose-dependent manner. Additionally, the effect of quercetin on endothelial cell proliferation was confirmed using human umbilical vein endothelial cells. The activity of quercetin on the proliferation of endothelial cells was stronger than that on A549, BEL-7402, MKN-45 tumor cells and NIH-3T3 fibroblast cells. The chicken chorioallantoic membrane assay revealed that addition of quercetin displayed an antiangiogenic effect in vivo. After exposure to quercetin, a decrease in the expression and activity of matrix metalloproteinase-2, which is involved in the angiogenic process of migration, invasion, and tube formation, was observed by reverse transcription-polymerase chain reaction (RT-PCR) and gelatin zymography. These findings suggest that quercetin has antiangiogenic potential and that this effect may be related to an influence on the expression and activity of matrix metalloproteinase-2.