Table of Contents

Volume 13, Issue 3

  February 1, 2012

  Pages 123 - 189

View covers archive

REVIEW

Fibroblast activation protein: A potential therapeutic target in cancer

Rui Liu, Hui Li, Liang Liu, Jinpu Yu and Xiubao Ren
Pages 123 - 129
http://dx.doi.org/10.4161/cbt.13.3.18696
Abstract | Full Text | PDF

The concept of targeting antigens selectively expressed on the surface of tumor capillary endothelial cells or in tumor stroma has emerged as a promising strategy for cancer therapeutics. Identification of stromal targets for anticancer therapy and development of selective inhibitors of these targets are of great clinical interest. Fibroblast activation protein (FAP), a member of the serine protease family, selectively expressed in the stromal fibroblasts associated with epithelial cancers, whereas with low or undetectable expression in the resting fibroblasts of normal adult tissues. The proteolytic activity of FAP has been shown to support tumor growth and proliferation, making it a potential target for novel anticancer therapies, such as those by immune-based approaches.




RESEARCH PAPERS

Dietary calcium supplementation enhances efficacy but also toxicity of EGFR inhibitor therapy for colon cancer

Erica Rinella, Eric Bankaitis and David Threadgill
Pages 130 - 137
http://dx.doi.org/10.4161/cbt.13.3.18690
Abstract | Full Text | PDF

The inverse correlation between levels of dietary calcium and colorectal cancer (CRC) incidence has been extensively investigated. However, the impact of supplemental calcium on cancer therapy remains unknown. We used four models of CRC, Caco-2 and HCT116 human cancer cell lines and Apc^Min/+ and azoxymethane carcinogen-induced mouse models, to investigate the impact of a Western-style diet low in calcium (0.05%) vs. a similar diet but supplemented with calcium (5%) on therapeutic targeting of the epidermal growth factor receptor (EGFR). We found that calcium supplementation combined with pharmacologic blockade of EGFR results in an additive effect on tumor growth inhibition in all models. Unexpectedly, the combined use of dietary calcium supplementation and EGFR inhibitors also resulted in elevated toxicity suggesting that careful consideration be given when combining dietary supplements with prescribed cancer therapies.

Dioscin induces cancer cell apoptosis through elevated oxidative stress mediated by downregulation of peroxiredoxins

Wang Zhiyu, Cheng Yue, Wang Neng, Wang Dong Mei, Li Ying Wei, Han Feng, Shen Jian Gang, Yang De Po, Guan Xin Yuan and Chen Jian-Ping
Pages 138 - 147
http://dx.doi.org/10.4161/cbt.13.3.18693
Abstract | Full Text | PDF

Dioscin has been shown to promote anticancer activity against several forms of cancers. However, its detailed molecular mechanisms have not been clarified. In this study, we demonstrate that dioscin induces apoptosis in cancer cells through the induction of oxidative stress. Treatment with cancer cells in vitro with dioscin resulted in rapid generation of reactive oxygen species (ROS) and the induction of mitochondrial pathway apoptosis in human esophageal cancer cell line Kyse510. Inhibition of oxidative stress by the antioxidant N-acetylcysteine blocked the induction of apoptosis by dioscin, indicating that ROS generation is the primary mechanism responsible for the proapoptotic activity of dioscin. Proteomic analysis and protein gel blotting further revealed peroxiredoxins 1 and 6 (PRDX 1 and 6), which are implicated in ROS metabolism and apoptosis, were associated with the anticancer effects of dioscin. Meanwhile, overexpression of PRDX 1 and 6 significantly blocked the elevated ROS and apoptosis induced by dioscin. In conclusion, we suggest that PRDX1 and PRDX6 are key targets in the process of dioscin-induced apoptosis that involves intracellular elevated ROS.

Downregulation of insulin-like growth factor-binding protein 7 in cisplatin-resistant non-small cell lung cancer

Jun Okamura, Yiping Huang, David Moon, Mariana Brait, Xiaofei Chang and Myoung Sook Kim
Pages 148 - 155
http://dx.doi.org/10.4161/cbt.13.3.18695
Abstract | Full Text | PDF

Cisplatin is an effective anticancer drug used to treat many types of cancer, including non-small cell lung carcinoma (NSCLCs), but development of resistance is the primary impediment in cancer treatment. Insulin-like growth factor-binding protein 7 (IGFBP7) is a secreted tumor suppressor that is inactivated in human lung cancer. IGFBP7 is known to alter sensitivity to interferon-based anticancer therapy, and here, we examined loss of IGFBP7 as a potential contributor to chemo-resistance to cisplatin. The transcriptional level of IGFBP7 was decreased in cisplatin-resistant human cancer cell lines and NSCLC xenografts. IGFBP7 knock-down increased cellular resistance to cisplatin and increased the level of mitogen-activated protein kinase phosphatases (MKP) 3 levels. The expression of MKP3 increased in a cisplatin-resistant NSCLC cell line and lung xenografts. MKP3 knock-down increased IGFBP7 level, indicating that MKP3 regulates IGFBP7. These findings suggest a novel molecular mechanism responsible for the tumor suppressive function of IGFBP7 in cisplatin-resistant human lung cancer and could lead to the development of IGFBP7 as a cisplatin-sensitizing agent.

Overexpression of centrosomal protein Nlp confers breast carcinoma resistance to paclitaxel

Weihong Zhao, Yongmei Song, Binghe Xu and Qimin Zhan
Pages 156 - 163
http://dx.doi.org/10.4161/cbt.13.3.18697
Abstract | Full Text | PDF

Nlp (ninein-like protein), an important molecule involved in centrosome maturation and spindle formation, plays an important role in tumorigenesis and its abnormal expression was recently observed in human breast and lung cancers. In this study, the correlation between overexpression of Nlp and paclitaxel chemosensitivity was investigated to explore the mechanisms of resistance to paclitaxel and to understand the effect of Nlp upon apoptosis induced by chemotherapeutic agents. Nlp expression vector was stably transfected into breast cancer MCF-7 cells. With Nlp overexpression, the survival rates, cell cycle distributions and apoptosis were analyzed in transfected MCF-7 cells by MTT test and FCM approach. The immunofluorescent assay was employed to detect the changes of microtubule after paclitaxel treatment. Immunoblotting analysis was used to examine expression of centrosomal proteins and apoptosis associated proteins. Subsequently, Nlp expression was retrospectively examined with 55 breast cancer samples derived from paclitaxel treated patients. Interestingly, the survival rates of MCF-7 cells with Nlp overexpressing were higher than that of control after paclitaxel treatment. Nlp overexpression promoted G₂-M arrest and attenuated apoptosis induced by paclitaxel, which was coupled with elevated Bcl-2 protein. Nlp expression significantly lessened the microtubule polymerization and bundling elicited by paclitaxel attributing to alteration on the structure or dynamics of β-tubulin but not on its expression. The breast cancer patients with high expression of Nlp were likely resistant to the treatment of paclitaxel, as the response rate in Nlp negative patients was 62.5%, whereas it was 58.3 and 15.8% in Nlp (+) and Nlp (++) patients respectively (p = 0.015). Nlp expression was positively correlated with those of Plk1 and PCNA. These findings provide insights into more rational chemotherapeutic regimens in clinical practice, and more effective approaches might be developed through targeting Nlp to increase chemotherapeutic sensitivity.

A single nucleotide polymorphism of the cholecystokinin-B receptor predicts risk for pancreatic cancer

Jill P. Smith, John Harms, Gail L. Matters, Christopher O. McGovern, Francesca M. Ruggiero, Jiangang Liao, Kristin K. Fino, Emily E. Ortega, Evan L. Gilius and John A. Phillips III
Pages 164 - 174
http://dx.doi.org/10.4161/cbt.13.3.18698
Abstract | Full Text | PDF

There currently are no tests available for early diagnosis or for the identification of patients at risk for development of pancreatic cancer. We report the discovery of single nucleotide polymorphism (SNP) in the cholecystokinin B receptor (CCKBR) gene predicts survival and risk of pancreatic cancer. Growth of human pancreatic cancer is stimulated by gastrin through the CCKBR and an alternatively spliced isoform of the CCKBR gene called CCKCR. One hundred and ten surgically resected benign and malignant pancreatic tissues as well as normal pancreas were prospectively evaluated for CCKBR genotype and protein expression. Analysis demonstrated the expression of the spliced isoform, CCKCR, was associated with a (SNP) (C > A) at position 32 of the intron 4 (IVS 4) of the CCKBR gene. Since the SNP is within an intron, it has not previously been identified in the GWAS studies. Only patients with the A/A or A/C genotypes, exhibited immunoreactivity to a selective CCKCR antibody. Survival among pancreatic cancer patients with the A-SNP was significantly shorter (p = 0.0001, hazard ratio = 3.63) compared with individuals with C/C genotype. Other variables such as surgical margins, lymph node status, histologic grade or adjuvant chemotherapy were not associated with survival. Furthermore, having one or two of the A-alleles was found to increase the risk of pancreatic adenocarcinoma by 174% (p = 0.0192) compared with the C/C wild type. Cancer cells transfected to overexpress the CCKCR demonstrated increased proliferation over controls. Genetic screening for this SNP may aid in early detection of pancreatic cancer in high risk subjects.

MicroRNA-101 (miR-101) post-transcriptionally regulates the expression of EP4 receptor in colon cancers

Anupama Chandramouli, Benjamin Chidi Onyeagucha, Melania E. Mercado-Pimentel, Lenka Stankova, Nisreen Abu Shahin, Bonnie J. LaFleur, Ronald L. Heimark, Achyut K. Bhattacharyya and Mark A. Nelson
Pages 175 - 183
http://dx.doi.org/10.4161/cbt.13.3.18874
Abstract | Full Text | PDF

Purpose: Expression of the PGE2 receptor, EP4, is up-regulated during colorectal carcinogenesis. However the mechanism leading to deregulation of the EP4 receptor is not known. The present study was conducted to investigate the regulation of EP4 receptor by miRNAs.

Experimental Design: We analyzed 26 colon cancers (i.e. 15 adenocarcinomas and 9 adenomas) and 16 normal colon specimens for EP4 receptor expression by immunohistochemistry. A bioinformatics approached identified putative microRNA binding sites with the 3'-UTR of the EP4 receptor. Both colon cancer cell lines and tumor specimens were analyzed for miR-101 and EP4 expression by qRT-PCR and Western analysis respectively and simultaneously in situ hybridizations was used to confirm our results. In vitro and in vivo assays were used to confirm our clinical findings.

Results: We observed an inverse correlation between the levels of miR-101 and EP4 receptor protein. Transfection of LS174T cells with miR-101 significantly suppressed a luciferase reporter containing the EP4 receptor-3'-UTR. In contrast, a mutant EP4 receptor-3'-UTR construct was unaffected. Ectopic expression of miR-101 markedly reduced cell proliferation and motility. Co-transfection of EP4 receptor could rescue colon cancer cells from the tumor suppressive effects of miR-101. Moreover, the pharmacologic inhibition of EP4 receptor signaling or silencing of EP4 receptor phenocopied the effect of miR-101. This is the first study to show that the EP4 receptor is negatively regulated by miR-101.

Conclusions: These data provide new insights in the modulation of EP-4 receptor expression at the post-transcriptional level by miR-101 and suggests therapeutic strategies against miR-101 targets may be warranted.

Combination with bortezomib enhances the antitumor effects of nanoparticle-encapsulated thiostrepton

Ming Wang and Andrei L. Gartel
Pages 184 - 189
http://dx.doi.org/10.4161/cbt.13.3.18875
Abstract | Full Text | PDF

Bortezomib is well-known for inducing cell death in cancer cells, specifically through the mechanism of proteasome inhibition. Thiostrepton, a thiazole antibiotic, has also been described for its proteasome inhibitory action, although differing slightly to bortezomib in the proteasomal site to which it is active. Previously we had shown the synergic effect of bortezomib and thiostrepton in breast cancer cells in vitro, where sub-apoptotic concentrations of both proteasome inhibitors resulted in synergic increase in cell death when combined as a treatment. Here, we administered such a combination to MDA-MB-231 xenograft tumors in vivo, and found that the effect of complementary proteasome inhibitors reduced tumor growth rates more efficiently than compared with when administered alone. Increased induction of apoptotic activity in tumors was found be associated with the growth inhibitory activity of combination treatment. Further examination additionally revealed that combination-treated tumors exhibited reduced proteasome activity, compared with non-treated and single drug-treated tumors. These data suggest that this drug combination may be useful as a therapy for solid tumors.