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Breast cancer is one of the most common cancers in women worldwide and metastasis is the major cause of breast cancer death. Development of new therapeutic agents for inhibiting breast cancer metastasis is therefore an urgent need. We previously demonstrated that recombinant DNA-derived viral capsid protein VP1 (rVP1) of foot-and-mouth disease virus-induced apoptosis of MCF-7 breast cancer cells in vitro. Here, we investigated whether rVP1 exhibits any inhibitory effects on migration/metastasis and human epidermal growth factor receptor 2 (HER-2), a well-known biomarker for poor prognosis of breast cancer. The effects of rVP1 on cancer cell migration/invasion and metastasis were evaluated using Transwell migration assay and animal cancer models of metastasis. Western blotting, RT-PCR, flow cytometry, immunohistochemistry, and immunofluorescence staining techniques were used to investigate the effects of rVP1 on HER-2 and signal transduction mediators. Non-cytotoxic concentrations of rVP1-induced mesenchymal-epithelial transition and significantly suppressed AP-2α and HER-2 expression as well as the migration and invasion of a variety of breast cancer cell lines in a β1-integrin-dependent manner in vitro. Gross and histopathologic examinations showed that rVP1 also suppressed metastasis of several breast cancer cell lines, including HER-2-overexpressing SK-BR-3 and BT-474 cells to lung, liver, or peripheral lymph node in orthotopic allograft/xenograft murine models. In addition, rVP1 significantly prolonged survival in breast cancer-bearing mice. Notably, no apparent side effects of rVP1 were detected, as shown by normal complete blood count levels and serum biochemistry profiles, including AST, ALT, BUN, and creatine. This study demonstrates that rVP1 suppresses the migration, invasion, and metastasis of breast cancer cells via binding to β1 integrin receptor and down-regulation of AP-2α and HER-2 expression. The effectiveness of rVP1 on inhibiting migration/metastasis of breast cancer and HER-2 expression suggests that it may be suitable for serving as potential therapeutics for metastatic breast cancer particularly HER-2-overexpressing cancer.

Background and Purpose: As prognosis for patients with metastatic ovarian cancer is generally poor, advances in treatment are needed. Here, we studied the mechanism of action of a recombinant viral capsid protein (rVP1) and explored its effect against ovarian tumour growth and metastasis in vivo., Experimental Approach: The human ovarian cancer cell line SKOV3 and BALB/cAnN-Foxn1 female nude mice were used. Effects of rVP1 on the viability, invasive ability, matrix metalloproteinase (MMP)-2 activity and cancer cell proliferation and metastasis were determined by cell proliferation assay, Matrigel invasion assay, gelatin zymographic analysis, as well as bioluminescence imaging and immunohistological analysis in xenograft mouse models respectively. Levels of total and phosphorylated focal adhesion kinase (FAK), PKB/Akt, phosphatase and tensin homologue (PTEN) and glycogen synthase kinase-3β (GSK-3β) were detected by Western blotting., Key Results: rVP1 promoted apoptosis and decreased invasion of human ovarian cancer cells. This effect of rVP1 was accompanied by activation of PTEN and GSK-3β as well as down-regulation of FAK, Akt and MMP-2. Anti-integrin antibodies or overexpression of constitutively active Akt reversed the cellular effects of rVP1. Orthotopic and intraperitoneal xenograft mouse models demonstrated that rVP1 attenuated survival and metastasis of human ovarian cancer SKOV3 cell line in vivo through selective regulation of Akt and GSK-3β activity as shown by bioluminescence imaging of mice and immunohistochemical analysis., Conclusion and Implications: These results indicate that negative regulation of Akt signalling and MMP-2 by rVP1 may have the potential to suppress ovarian tumour growth and metastasis in vivo., (© 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.)

Background: The application of viral elements in tumor therapy is one facet of cancer research. Recombinant capsid protein VP1 (rVP1) of foot-and-mouth disease virus has previously been demonstrated to induce apoptosis in cancer cell lines. Here, we aim to further investigate its apoptotic mechanism and possible anti-metastatic effect in murine models of hepatocellular carcinoma (HCC), one of the most common human cancers worldwide., Methodology/principal Findings: Treatment with rVP1 inhibited cell proliferation in two murine HCC cell lines, BNL and Hepa1-6, with IC₅₀ values in the range of 0.1-0.2 µM. rVP1 also induced apoptosis in these cells, which was mediated by Akt deactivation and dissociation of Ku70-Bax, and resulted in conformational changes and mitochondrial translocation of Bax, leading to the activation of caspases-9, -3 and -7. Treatment with 0.025 µM rVP1, which did not affect the viability of normal hepatocytes, suppressed cell migration and invasion via attenuating CCL2 production. The production of CCL2 was modulated by Akt-dependent NF-κB activation that was decreased after rVP1 treatment. The in vivo antitumor effects of rVP1 were assessed in both subcutaneous and orthotopic mouse models of HCC in immune-competent BALB/c mice. Intratumoral delivery of rVP1 inhibited subcutaneous tumor growth as a result of increased apoptosis. Intravenous administration of rVP1 in an orthotopic HCC model suppressed tumor growth, inhibited intra-hepatic metastasis, and prolonged survival. Furthermore, a decrease in the serum level of CCL2 was observed in rVP1-treated mice., Conclusions/significance: The data presented herein suggest that, via inhibiting Akt phosphorylation, rVP1 suppresses the growth, migration, and invasion of murine HCC cells by inducing apoptosis and attenuating CCL2 production both in vitro and in vivo. Recombinant protein VP1 thus has the potential to be developed as a new therapeutic agent for HCC.

Streptococcus iniae (S. iniae) has become an important aquatic pathogen to cause serious streptococcosis outbreaks in cultured fish species, thus resulting in great economic losses in the worldwide aquaculture industry. Although vaccination has been so far an effective strategy to alleviate the threats of streptococcosis, antigenic variations displayed by different strains/isolates of S. iniae have brought about a severe challenge in the vaccine development. In the present study, three local S. iniae isolates, MML SI-007, MML SI-018 and MML SI-148, were first evaluated for their virulence in tilapia. Proteomics was then performed to analyze protein profiles between the highly virulent isolate (MML SI-007) and lowly virulent isolate (MML SI-018) in order to identify important virulence factors/antigens shared by different isolates. After proteomics, eleven proteins that displayed more than four times the differences in expression between MML SI-007 and MML SI-018 were identified. Two proteins, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and superoxide dismutase (SOD), were selected to be vaccine candidates for respectively cloning their genes and expressing their recombinant proteins, rGAPDH and rSOD. After peritoneal vaccination in tilapia, mixed recombinant proteins (rGAPDH + rSOD) elicited significantly higher serum titers and lymphocyte proliferation than individual recombinant proteins (rGAPDH or rSOD). In addition, maximum production of IL-6 in the head kidney was detected in fish peritoneally vaccinated with mixed recombinant proteins. More importantly, 84% (21/25) of tilapia peritoneally vaccinated with mixed recombinant proteins survived at least four weeks after a lethal peritoneal challenge of heterologous S. iniae (MML SI-148). Taken together, our results have pointed out that both GAPDH and SOD identified via proteomics are crucial virulence factors that can be protective antigens for future development of an effective cross-protective subunit vaccine against S. iniae. • The distinct S. iniae virulence was assessed by peritoneal infection in tilapia. • S. iniae crucial virulence factors, GAPDH and SOD, were identified by proteomics. • Recombinant proteins, rGAPDH and rSOD, still displayed their strong antigenicity. • rGAPDH + rSOD readily elicited protective immunity against S. iniae in tilapia. [ABSTRACT FROM AUTHOR]