Inhibition of the aquaporin 3 water channel increases the sensitivity of prostate cancer cells to cryotherapy

Aquaporins (AQPs) are intrinsic membrane proteins that facilitate selective water and small solute movement across the plasma membrane. In this study, we investigate the role of inhibiting AQPs in sensitising prostate cancer cells to cryotherapy. PC-3 and DU145 prostate cancer cells were cooled to 0, −5 and −10°C. The expression of AQP3 in response to freezing was determined using real-time quantitative polymerase chain reaction (RT–qPCR) and western blot analysis. Aquaporins were inhibited using mercuric chloride (HgCl2) and small interfering RNA (siRNA) duplex, and cell survival was assessed using a colorimetric assay. There was a significant increase in AQP3 expression in response to freezing. Cells treated with AQP3 siRNA were more sensitive to cryoinjury compared with control cells (P<0.001). Inhibition of the AQPs by HgCl2 also increased the sensitivity of both cell lines to cryoinjury and there was a complete loss of cell viability at −10°C (P<0.01). In conclusion, we have shown that AQP3 is involved directly in cryoinjury. Inhibition of AQP3 increases the sensitivity of prostate cancer cells to freezing. This strategy may be exploited in the clinic to improve the efficacy of prostate cryotherapy

ToMI-FBA: A genome-scale metabolic flux based algorithm to select optimum hosts and media formulations for expressing pathways of interest

The Total Membrane Influx constrained Flux Balance Analysis (ToMI-FBA) algorithm was developed in this research as a new tool to help researchers decide which microbial host and medium formulation are optimal for expressing a new metabolic pathway. ToMI-FBA relies on genome-scale metabolic flux modeling and a novel in silico cell membrane influx constraint that specifies the flux of atoms (not molecules) into the cell through all possible membrane transporters. The ToMI constraint is constructed through the addition of an extra row and column to the stoichiometric matrix of a genome-scale metabolic flux model. In this research, the mathematical formulation of the ToMI constraint is given along with four case studies that demonstrate its usefulness. In Case Study 1, ToMI-FBA returned an optimal culture medium formulation for the production of isobutanol from Bacillus subtilis. Significant levels of L-valine were recommended to optimize production, and this result has been observed experimentally. In Case Study 2, it is demonstrated how the carbon to nitrogen uptake ratio can be specified as an additional ToMI-FBA constraint. This was investigated for maximizing medium chain length polyhydroxyalkanoates (mcl-PHA) production from Pseudomonas putida KT2440. In Case Study 3, ToMI-FBA revealed a strategy of adding cellobiose as a means to increase ethanol selectivity during the stationary growth phase of Clostridium acetobutylicum ATCC 824. This strategy was also validated experimentally. Finally, in Case Study 4, B. subtilis was identified as a superior host to Escherichia coli, Saccharomyces cerevisiae, and Synechocystis PCC6803 for the production of artemisinate

EN2: A candidate antigen for the development of targeted therapies in ovarian cancer.

Background: Ovarian cancer remains the most lethal gynaecologic tumour in the Western world. Stimulation of the immune system to consolidate response to chemotherapy can potentially be beneficial however so far none of the vaccination strategies have offered survival advantage. Thus identifying and targeting clinically relevant antigens for immunotherapy continues to be an important research strategy. We have evaluated Engrailed-2 (EN2) as a potential target for vaccine strategy. EN2 is a homeodomain-containing transcription factor with a multifunctional role in neural development. There is evidence that over-expression of EN2 protein maybe linked to tumour development. Methods: Ovarian cancer cell lines were analysed by FACS for EN2 cell surface expression. EN2 expression in ovarian cancer tissue arrays were done by immunohistochemistry. A serum analysis (ELISA) was done to evaluate the presence of antibodies to EN2 in ovarian cancer patients and age-matched controls. A set of potentially immunogenic HLA-A2 restricted epitopes from the EN2 protein was identified using a computer algorithm SYFPEITHI. These peptides have been tested on HLA-A2 positive ovarian cancer patients’ PBMC using an in vitro culture method. The specificity of these T cell lines was analysed against T2 target cells loaded with or without EN2 peptides Results: Cell surface expression of EN2 was observed in ovarian cancer cell lines OVCAR3, OV90, CaOV-3, ES-2 and SKOV-3 of which ES-2 and SKOV3 showed strong expression. EN2 was also present in approximately 80% of ovarian cancer tissues whereas EN-2 expression was very low (<10%) or absent in normal tissues. Out of the 67 ovarian cancer patients 20.9% (14/67) had antibodies against EN2 compared to 2.4% (1/42) of age-matched female controls. 4 of the identified EN2 epitopes were able to generate peptide specific cytotoxic T lymphocytes in the ovarian cancer patients tested. Conclusions: The over-expression and immunogenicity of EN2 in ovarian cancer makes it a credible antigen to exploit as a novel target for ovarian cancer immunotherapy.