Table of Contents

Volume 13, Issue 4

  February 15, 2012

  Pages 191 - 236

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RESEARCH PAPERS

Thymosin β-4 in colorectal cancer is localized predominantly at the invasion front in tumor cells undergoing epithelial mesenchymal transition

Sonia Nemolato, Angelo Restivo, Tiziana Cabras, Pierpaolo Coni, Luigi Zorcolo, Germano Orrù, Mattia Fanari, Flaviana Cau, Clara Gerosa, Daniela Fanni, Irene Messana, Massimo Castagnola, Giuseppe Casula and Gavino Faa
Pages 191 - 197
http://dx.doi.org/10.4161/cbt.13.4.18691
Abstract | Full Text | PDF

Objective

Thymosin β-4 (Tβ₄) is a ubiquitous peptide that plays pivotal roles in the cytoskeletal system and in cell differentiation during embryogenesis. Recently, a role for Tβ₄ has been proposed in experimental and human carcinogenesis. This study was aimed at evaluating the correlation between Tβ₄ immunoractivity and colorectal cancer, with particular attemption to tumor cells undergoing epithelial-mesenchymal transition.

Methods and Results

86 intestinal biopsies were retrospectively analyzed including 76 colorectal adenocarcinomas with evident features of epithelial-mesenchymal transition, and 10 samples of normal colorectal mucosa. Paraffin sections were immunostained for Tβ₄ and for E-cadherin. Total RNA was isolated from frozen specimens obtained, at surgery, from the normal colon mucosa, the deeper regions and the superficial tumor regions in four cases of colon cancer. Tβ₄ immunoreactivity was detected in the vast majority (59/76) of colon carcinomas, showing a patchy distribution, with well differentiated areas significantly more reactive than the less differentiated tumor zones. We also noted a zonal pattern in the majority of tumors, characterized by a progressive increase in immunostaining for Tβ₄ from the superficial toward the deepest tumor regions. The strongest expression for Tβ₄ was frequently detected in invading tumor cells with features of epithelial-mesenchymal transition. The increase in reactivity for Tβ₄ matched with a progressive decrease in E-cadherin expression in invading cancer cells. At mRNA level, the differences in Tβ₄ expression between the surrounding colon mucosa and the tumors samples were not significant.

Conclusions

Our data show that Tβ₄ is expressed in the majority of colon cancers, with preferential immunoreactivity in deep tumor regions. The preferential expression of the peptide and the increase in intensity of the immunostaining at the invasion front suggests a possible link between the peptide and the process of epithelial mesenchymal transition, suggesting a role for Tβ₄ in colorectal cancer invasion and metastasis.

HIPK2 downregulates vimentin and inhibits breast cancer cell invasion

Cristina Nodale, Michal Sheffer, Jasmine Jacob-Hirsch, Valentina Folgiero, Rita Falcioni, Aurora Aiello, Alessia Garufi, Gideon Rechavi, David Givol and Gabriella D’Orazi
Pages 198 - 205
http://dx.doi.org/10.4161/cbt.13.4.18694
Abstract | Full Text | PDF

Vimentin, a mesenchymal marker, is frequently overexpressed in epithelial carcinomas undergoing epithelial to mesenchymal transition (EMT), a condition correlated with invasiveness and poor prognosis. Therefore, vimentin is a potential molecular target for anticancer therapy. Emerging studies in experimental models underscore the functions of homeodomain-interacting protein kinase 2 (HIPK2) as potential oncosuppressor by acting as transcriptional corepressor or catalytic activator of molecules involved in apoptosis and response to antitumor drugs. However, an involvement of HIPK2 in limiting tumor invasion remains to be elucidated. This study, by starting with a microarray analysis, demonstrates that HIPK2 downregulates vimentin expression in invasive, vimentin-positive, MDA-MB-231 breast cancer cells and in the non-invasive MCF7 breast cancer cells subjected to chemical hypoxia, a drive for mesenchymal shift and tumor invasion. At functional level, vimentin downregulation by HIPK2 correlates with inhibition of breast tumor cell invasion. Together, these data show that vimentin is a novel target for HIPK2 repressor function and that HIPK2-mediated vimentin downregulation can contribute to inhibition of breast cancer cells invasion that might be applied in clinical therapy.

RGD-conjugated albumin nanoparticles as a novel delivery vehicle in pancreatic cancer therapy

Shunrong Ji, Jin Xu, Bo Zhang, Wantong Yao, Wenyan Xu, Wenzhe Wu, Yongfeng Xu, Hao Wang, Quanxing Ni, Huimin Hou and Xianjun Yu
Pages 206 - 215
http://dx.doi.org/10.4161/cbt.13.4.18692
Abstract | Full Text | PDF

Integrin αvβ3 receptor is expressed on several types of cancer cells, including pancreatic cancer cells, and plays an important role in tumor growth and metastasis. The ability to target the integrin αvβ3 receptor on cancer cells increases the efficacy of targeted therapy and reduces the side effects. The aim of this study is to develop a novel arginine-glycine-aspartic acid (RGD) peptide-conjugated albumin nanoparticle to enhance the intracellular uptake of anticancer drug into the pancreatic cancer cells through receptor-mediated endocytosis. In cellular uptake studies, the fluorescent signal of RGD-conjugated BSANPs in BxPC3 cells was higher than that of BSANPs without RGD conjugation as determined by fluorescence spectrophotometer. We also found that BSANPs bound to BxPC3 cells in a time- and concentration-dependent manner. The uptake of RGD-conjugated BSANPs by pancreatic cancer cells was inhibited by an excess amount of free RGD peptide, indicating that the binding and/or uptake were mediated by the αvβ3 receptor. Furthermore, the nanoparticles were found to be located close to the nuclei by using laser scanning confocal microscopy. Besides, no significant in vitro cytotoxicity was observed as measured with MTT assay. Both in vitro and in vivo antitumor efficacy was improved by targeting gemcitabine-loaded nanoparticles to BxPC-3 cells using RGD peptides. Therefore, the RGD-conjugated BSANPs hold great potential as an effective drug delivery system to deliver therapeutic agents to pancreatic cancer.

HIF prolyl hydroxylase-2 inhibition diminishes tumor growth through matrix metalloproteinase-induced TGFβ activation

Anne Klotzsche-von Ameln, Antje Muschter, Markus M. Heimesaat, Georg Breier and Ben Wielockx
Pages 216 - 223
http://dx.doi.org/10.4161/cbt.13.4.18830
Abstract | Full Text | PDF

A right amount of oxygen and nutrients is essential for a tumor to develop. The role of oxygen dependent pathways and their regulators is therefore of utmost importance although little is known about the detailed impact they can have. Recently we have shown that inhibition of the oxygen sensor PHD2 in tumor cells blocks tumor growth due to the anti-proliferative activity of TGFβ. In this study, we refined these results by comparing different shPHD2 sequences in depth in the early phase of tumor growth. Our findings also reveal an intriguing role for MMP2 and MT1MMP in these settings, as these activated proteases display an anti-proliferative characteristic through the activation of downstream TGFβ targets. In conclusion, PHD2 inhibition is essential for the regulation of the anti-tumoral activity in mouse tumor cells and might bring some new insight in our understanding of tumor growth inhibition.

OSU-03012 suppresses GRP78/BiP expression that causes PERK-dependent increases in tumor cell killing

Laurence Booth, Sophie C. Cazanave, Hossein A. Hamed, Adly Yacoub, Besim Ogretmen, Ching-Shih Chen, Steven Grant and Paul Dent
Pages 224 - 236
http://dx.doi.org/10.4161/cbt.13.4.18877
Abstract | Full Text | PDF

We have further defined mechanism(s) by which the drug OSU-03012 (OSU) kills tumor cells. OSU lethality was suppressed by knock down of PERK and enhanced by knock down of ATF6 and IRE1α. OSU treatment suppressed expression of the chaperone, BiP/GRP78, and did so through reduced stability of the protein. Knock down of BiP/GRP78 further enhanced OSU lethality. Overexpression of BiP/GRP78 abolished OSU toxicity. Pre-treatment of cells with OSU enhanced radiosensitivity to a greater extent than concomitant or sequential drug treatment with radiation exposure. Expression of a mutant active p110 PI3K, or mutant active forms of the EGFR in GBM cells did not differentially suppress OSU killing. In contrast loss of PTEN function reduced OSU lethality, without altering AKT, p70 S6K or mTOR activity, or the drug’s ability to radiosensitize GBM cells. Knock down of PTEN protected cells from OSU and radiation treatment whereas re-expression of PTEN facilitated drug lethality and radiosensitization. In a dose-dependent fashion OSU prolonged the survival of mice carrying GBM tumors and interacted with radiotherapy to further prolong survival. Collectively, our data show that reduced BiP/GRP78 levels play a key role in OSU-3012 toxicity in GBM cells, and that this drug has in vivo activity against an invasive primary human GBM isolate.