Table of Contents

Volume 12, Issue 6

  September 15, 2011

  Pages 467 - 555

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 Issue Catalogue (MARC XML)

REVIEW

Open Access Article

Anticancer biology of Azadirachta indica L (neem): A mini review

Rajkumar Paul, Murari Prasad and Nand K. Sah
Pages 467 - 476
http://dx.doi.org/10.4161/cbt.12.6.16850
Abstract | PDF

Neem (Azadirachta indica), a member of the Meliaceae family, is a fast growing tropical evergreen tree with a highly branched and stout, solid stem. Because of its tremendous therapeutic, domestic, agricultural and ethnomedicinal significance, and its proximity with human culture and civilization, neem has been called “the wonder tree” and “nature’s drug store.” All parts of this tree, particularly the leaves, bark, seed-oil and their purified products are widely used for treatment of cancer. Over 60 different types of biochemicals including terpenoids and steroids have been purified from this plant. Pre-clinical research work done during the last decade has fine-tuned our understanding of the anticancer properties of the crude and purified products from this plant. The anticancer properties of the plant have been studied largely in terms of its preventive, protective, tumor-suppressive, immunomodulatory and apoptotic effects against various types of cancer and their molecular mechanisms. This review aims at scanning scattered literature on “the anticancer biology of A. indica,” related toxicity problems and future perspectives. The cogent data on the anticancer biology of products from A. indica deserve multi-institutional clinical trials as early as possible. The prospects of relatively cheaper cancer drugs could then be brighter, particularly for the under-privileged cancer patients of the world.




RESEARCH PAPERS

Open Access Article

MicroRNA-34a targets notch1 and inhibits cell proliferation in glioblastoma multiforme

Wen-Bo Li, Min-Wang Ma, Li-Jie Dong, Fei Wang, Lu-Xia Chen and Xiao-Rong Li
Pages 477 - 483
http://dx.doi.org/10.4161/cbt.12.6.16300
Abstract | PDF

Aberrant expression of microRNAs (miRNAs) has been implicated in cancer initiation and progression. In this study, we found that microRNA-34a (miR-34a) is significantly downregulated in glioblastoma multiforme (GBM) specimens compared with normal brain tissues. Growth curve and colony formation assays revealed that miR-34a suppresses proliferation of U373MG and SHG44 glioblastoma cells. Overexpression of miR-34a could induce apoptosis of glioblastoma cells. Also, we identified notch1 as a direct target gene of miR-34a. Knockdown of notch1 showed similar cellular functions as overexpression of miR-34a both in vitro and in vivo. Collectively, our findings show that miR-34a is downregulated in GBM cells and inhibits GBM growth by targeting notch1.

Open Access Article

The DNA damage mark pH2AX differentiates the cytotoxic effects of small molecule HDAC inhibitors in ovarian cancer cells

Andrew J. Wilson, Edward Holson, Florence Wagner, Yan-Ling Zhang, Daniel M. Fass, Stephen J. Haggarty, Srividya Bhaskara, Scott W. Hiebert, Stuart L. Schreiber and Dineo Khabele
Pages 484 - 493
http://dx.doi.org/10.4161/cbt.12.6.15956
Abstract | PDF

High grade epithelial ovarian cancers are relatively sensitive to DNA damaging platinum-based chemotherapy, suggesting that the dependencies of ovarian tumors on DNA damage response pathways can be harnessed for therapeutic purposes. Our goal was to determine if the DNA damage mark gamma-H2AX phosphorylation (pH2AX) could be used to identify suitable cytotoxic histone deacetylase inhibitors (HDACi) for ovarian cancer treatment. Nineteen chemically diverse HDACi compounds were tested in 7 ovarian cancer cell lines. Fluorescent, biochemical and cell-based assays were performed to assess DNA damage by induction of pH2AX and to measure cell viability and apoptosis. The relationships between pH2AX and the cellular effects of cell viability and apoptosis were calculated. Selected HDACi were tested in combination with cisplatin and other DNA damaging agents to determine if the HDACi improved upon the effects of the DNA damaging agents. The HDACi compounds induced differing levels of pH2AX expression. High levels of pH2AX in HDACi-treated ovarian cancer cells were tightly associated with decreased cell viability and increased apoptosis. Consequently, a ketone-based HDACi was chosen and found to enhance the effects of cisplatin, even in ovarian cancer cells with extreme resistance to DNA damaging drugs. In conclusion, a fluorescent-based assay for pH2AX can be used to determine cellular responses to HDACi in vitro and may be a useful tool to identify potentially more effective HDACi for the treatment of ovarian cancer. In addition, these results lend support to the inclusion of ketone-derived HDACi compounds for future development.

Open Access Article

Interferon-α sensitizes human gastric cancer cells to TRAIL-induced apoptosis via activation of the c-CBL-dependent MAPK/ERK pathway

Jinglei Qu, Mingfang Zhao, Yuee Teng, Ye Zhang, Kezuo Hou, Youhong Jiang, Xianghong Yang, Hong Shang, Xiujuan Qu and Yunpeng Liu
Pages 494 - 502
http://dx.doi.org/10.4161/cbt.12.6.15973
Abstract | PDF

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family that induces apoptosis in cancer cells. However, gastric cancer cells are insensitive to TRAIL. In the present study, we show that pretreatment with IFN-α enhanced TRAIL-induced apoptosis of gastric cancer MGC803 cells. IFN-α up-regulated death receptor 5 (DR5) expression and down-regulated survivin expression. Furthermore, extracellular-regulated protein kinase (ERK1/2) activation was induced by IFN-α, and a combination of IFN-α and TRAIL led to further activation of ERK1/2. Inhibition of the MAPK/ERK signaling pathway partially reversed apoptosis, as well as the expression patterns of DR5 and survivin. Moreover, the expression of the c-casitas B-lineage lymphoma (c-Cbl) family was down-regulated by IFN-α. Transfection of c-Cbl suppressed IFN-α-induced ERK activation. These results indicate that IFN-α enhances TRAIL-induced apoptosis in gastric cancer cells at least partially via downregulation of c-Cbl, and subsequent up-regulation of the MAPK/ERK pathway.

Open Access Article

Interaction of the ARF tumor suppressor with cytosolic HSP70 contributes to its autophagy function

Julia Pimkina and Maureen E. Murphy
Pages 503 - 509
http://dx.doi.org/10.4161/cbt.12.6.15976
Abstract | PDF

The p14/p19^ARF (ARF) tumor suppressor gene is frequently mutated in human cancer. Recently ARF has been shown to localize to mitochondria and to induce autophagy. However the controls that regulate the trafficking of ARF to mitochondria remain unknown. We recently reported that 2-phenylethynesulfonamide (PES) selectively interacts with cytosolic heat shock protein 70 (HSP70) and inhibits its function; we further showed that PES promotes the death of tumor cells, and that this is associated with an impairment of lysosome function and an inhibition of autophagy. In the present work we used a mass spectrometry-based approach to identify mitochondrial ARF-binding proteins. We report that mitochondrial ARF interacts with HSP70. We show that treatment of cells with PES blocks the trafficking of ARF to mitochondria, indicating that interaction with HSP70 mediates the mitochondrial localization of ARF. We also show that PES inhibits the ability of ARF to induce autophagy, supporting the premise that localization to this organelle is critical for ARF-induced autophagy. Finally, we report that cells expressing high levels of ARF are more sensitive to PES than counterparts with ARF silenced. High levels of ARF are characteristic of tumor cells with enhanced MAPK signaling and advanced stage; therefore, these data support the premise that PES may show preferential cytotoxicity to advanced stage cancers.

Open Access Article

Quantitative tissue proteomics of esophageal squamous cell carcinoma for novel biomarker discovery

Harsh Pawar, Manoj Kumar Kashyap, Nandini A. Sahasrabuddhe, Santosh Renuse, H. C. Harsha, Praveen Kumar, Jyoti Sharma, Kumaran Kandasamy, Arivusudar Marimuthu, Bipin Nair, Sudha Rajagopalan, Jagadeesha Maharudraiah, Chennagiri Shrinivasamurthy Premalatha, Kariyanakatte Veeraiah Veerendra Kumar, M. Vijayakumar, Raghothama Chaerkady, Thotterthodi Subrahmanya Keshava Prasad, Rekha V. Kumar and Akhilesh Pandey
Pages 510 - 522
http://dx.doi.org/10.4161/cbt.12.6.16833
Abstract | PDF

Esophageal squamous cell carcinoma (ESCC) is among the top ten most frequent malignancies worldwide. In this study, our objective was to identify potential biomarkers for ESCC through a quantitative proteomic approach using the isobaric tags for relative and absolute quantitation (iTRAQ) approach. We compared the protein expression profiles of ESCC tumor tissues with the corresponding adjacent normal tissue from ten patients. LC-MS/MS analysis of strong cation exchange chromatography fractions was carried out on an Accurate Mass QTOF mass spectrometer, which led to the identification of 687 proteins. In all, 257 proteins were identified as differentially expressed in ESCC as compared to normal. We found several previously known protein biomarkers to be upregulated in ESCC including thrombospondin 1 (THBS1), periostin 1 (POSTN) and heat shock 70 kDa protein 9 (HSPA9) confirming the validity of our approach. In addition, several novel proteins that had not been reported previously were identified in our screen. These novel biomarker candidates included prosaposin (PSAP), plectin 1 (PLEC1) and protein disulfide isomerase A 4 (PDIA4) that were further validated to be overexpressed by immunohistochemical labeling using tissue microarrays. The success of our study shows that this mass spectrometric strategy can be applied to cancers in general to develop a panel of candidate biomarkers, which can then be validated by other techniques.

Open Access Article

Hyperthermia increases the therapeutic efficacy of survivinT34A in mouse tumor models

Zhi-Mian Li, Yu-Wei Zhao, Cheng-Jian Zhao, Xiao-Ping Zhang, Li-Juan Chen, Yu-Quan Wei and Han-Shuo Yang
Pages 523 - 530
http://dx.doi.org/10.4161/cbt.12.6.15983
Abstract | PDF

The use of survivinT34A mutant targeted disruption of survivin, the strongest inhibitor of apoptosis protein overexpressed in tumors, has proved a promising strategy for advanced cancers. However, hyperthermia, as a cytotoxic enhancer, regularly activates the expression of survivin to counteract the heat-induced antitumor activity. Here, we investigated the combinational antitumor effect by using liposome-encapsulated mouse survivinT34A and hyperthermia in mouse models. We observed that the combination treatment of surivinT34A and hyperthermia significantly increased the growth inhibition and apoptosis of tumor cells in vitro compared with single treatment or other controls, which was similar to the effect of survivin silencing in combination with hyperthermia. Moreover, the inhibition of tumor growth in vivo was also remarkably enhanced by combination of surivinT34A and hyperthermia when compared with other treatments. Naturally, the tumor tissues in combination treatment presented the larger necrosis-like areas, more apoptotic cells and less microvessel density. Our findings suggest that the antitumor efficacy of survivin disruption can be enhanced by hyperthermia, which might be a new feasible approach for cancer therapy.

Open Access Article

c-Met-Akt pathway-mediated enhancement of inhibitory c-Raf phosphorylation is involved in vitamin K1 and sorafenib synergy on HCC growth inhibition

Brian I. Carr, Ziqiu Wang, Meifang Wang, Aldo Cavallini, Rosalba D’Alessandro and Maria Gratzia Refolo
Pages 531 - 538
http://dx.doi.org/10.4161/cbt.12.6.16053
Abstract | PDF

Sorafenib is an FDA-approved agent for treatment of human hepatocellular carcinoma (HCC), but tumor shrinkage is minor. We therefore developed a strategy to combine K vitamins with sorafenib to treat HCC, and found that this combination enhanced sorafenib-induced HCC cell growth inhibition. To explore the mechanisms involved, we examined the role of Raf kinase, since both vitamins K and sorafenib were reported to inhibit tumor cell growth via Raf signaling pathway. We found that whereas lower concentration of vitamin K1 (25 μM) or sorafenib (2.5 μM) alone slightly induced c-Raf phosphorylation at both Ser-43 and Ser-259, combination vitamin K1 plus sorafenib resulted in strong c-Raf phosphorylation at these two serine residues. A Raf kinase activity assay confirmed that combination vitamin K1 plus sorafenib had a synergistic inhibitory effect on it. Since c-Raf phosphorylation at Ser-43 and Ser-259 can be regulated by either PKA or Akt kinase, we examined the effects of both vitamin K1 and sorafenib on their phosphorylation. Although vitamin K1 or sorafenib alone induced PKA phosphorylation, no enhanced phosphorylation effects on PKA were found using this combination. However, vitamin K1 enhanced sorafenib-induced c-Met phosphorylation at Tyr-1349, a DEP-1 protein phosphatase acting site, and consequently induced phosphorylation of PI3K-Akt. Both PI3K inhibitor Ly294002 as well as dominate negative Akt plasmid transfection antagonized vitamin K1 plus sorafenib actions on c-Raf phosphorylation and cell growth inhibition, suggesting that c-Met-PI3K-Akt signaling pathway mediated inhibitory c-Raf phosphorylation may play a central role in vitamin K1 plus sorafenib synergy in inhibiting HCC cell growth.

Open Access Article

Oncogenic roles of astrocyte elevated gene-1 (AEG-1) in osteosarcoma progression and prognosis

Feng Wang, Zun-Fu Ke, Shi-Jun Sun, Wen-Fang Chen, Shi-Cong Yang, Shu-Hua Li, Xiao-Peng Mao and Lian-Tang Wang
Pages 539 - 548
http://dx.doi.org/10.4161/cbt.12.6.16301
Abstract | PDF

Astrocyte elevated gene-1 (AEG-1) is overexpressed in several cancers and plays an important role in cancer progression. However, AEG-1 expression, biological function, and clinical significance in osteosarcoma have not been uncovered. Utilizing manipulated human osteosarcoma cell lines and osteosarcoma tissues, we found that increasing expression of AEG-1 enhanced osteosarcoma cell proliferation and invasion in vitro, and knockdown of AEG-1 significantly attenuated osteosarcoma cell malignancy. Moreover, AEG-1 was overexpressed in osteosarcoma tissues, and overexpression of AEG-1 was strongly associated with gender (p = 0.018), clinical stages (p < 0.001), classification (p < 0.001), metastasis (p = 0.013), differentiation (p < 0.001), and poor survival (p = 0.021). Mechanistic studies conducted in vitro and in vivo revealed that AEG-1-mediated carcinogenesis and invasiveness might be through upregulating MMP-2. Taken together, our data strongly suggest that AEG-1 plays a crucial role in osteosarcoma progression through MMP-2, and AEG-1 could be a useful biomarker for the prediction of osteosarcoma progression and prognosis.

Open Access Article

Augmentation of NVP-BEZ235's anticancer activity against human lung cancer cells by blockage of autophagy

Cheng-Xiong Xu, Liqun Zhao, Ping Yue, Guofu Fang, Hui Tao, Taofeek K. Owonikoko, Suresh S. Ramalingam, Fadlo R. Khuri and Shi-Yong Sun
Pages 549 - 555
http://dx.doi.org/10.4161/cbt.12.6.16397
Abstract | PDF

Autophagy is a cellular lysosomal degradation pathway essential for regulation of cell survival and death to maintain homeostasis. This process is negatively regulated by mammalian target of rapamycin (mTOR) signaling and often counteracts efficacy of certain cancer therapeutic agents. NVP-BEZ235 (BEZ235) is a novel, orally bioavailable dual PI3K/mTOR inhibitor that has exhibited promising activity against non-small cell lung cancer (NSCLC) in preclinical models. The current study focuses on evaluating the role of BEZ235 in regulating autophagy. BEZ235 was effective in inhibiting the growth of NSCLC cells including induction of apoptosis. It also potently induced the expression of type-II LC3, indicating induction of autophagy. When BEZ235 was used in combination with the lysosomal or autophagic inhibitor chloroquine (CQ), enhanced inhibitory effects on monolayer growth and colony formation of NSCLC cells was observed. In addition, enhanced induction of apoptosis was also detected in cells exposed to the combination of BEZ235 and CQ. Moreover, the combination of BEZ235 and CQ was more effective than each single agent alone in inhibiting the growth of NSCLC xenografts in nude mice. Thus, induction of autophagy by BEZ235 appears to be a survival mechanism that may counteract its anticancer effects. Based on these, we suggest a strategy to enhance BEZ235's anticancer efficacy by blockade of autophagy.