MSLN Gene Silencing Has an Anti-Malignant Effect on Cell Lines Overexpressing Mesothelin Deriving from Malignant Pleural Mesothelioma

Abstract

Genes involved in the carcinogenetic mechanisms underlying malignant pleural mesothelioma (MPM) are still poorly characterized. So far, mesothelin (MSLN) has aroused the most interest. It encodes for a membrane glycoprotein, frequently over-expressed in various malignancies such as MPM, and ovarian and pancreatic cancers. It has been proposed as a diagnostic and immunotherapeutic target with promising results. However, an alternative therapeutic approach seems to rise, whereby synthetic molecules, such as antisense oligonucleotides, could be used to inhibit MSLN activity. To date, such a gene-level inhibition has been attempted in two studies only, both on pancreatic and ovarian carcinoma cell lines, with the use of silencing RNA approaches. With regard to MPM, only one cell line (H2373) has been employed to study the effects of MSLN depletion. Indeed, the knowledge on the role of MSLN in MPM needs expanding. Accordingly, we investigated the expression of MSLN in a panel of three MPM cell lines, i.e. NCI-H28, Mero-14, and IstMes2; one non-MPM cell line was used as reference (Met5A). MSLN knock-down experiments on MSLN-overexpressing cells were also performed through silencing RNA (siRNA) to verify whether previous findings could be generalized to a different set of cell cultures. In agreement with previous studies, transient MSLN-silencing caused decreased proliferation rate and reduced invasive capacity and sphere formation in MSLN-overexpressing Mero-14 cells. Moreover, MSLN-siRNA combined with cisplatin, triggered a marked increase in apoptosis and a decrease in proliferation as compared to cells treated with each agent alone, thereby suggesting a sensitizing effect of siRNA towards cisplatin. In summary, our findings confirm that MSLN should be considered a key molecular target for novel gene-based targeted therapies of cancer.

Diagnosis and Treatment of Malignant Pleural Mesothelioma

“…To this end, different strategies, such as "suicide genes" (which make the tumor sensitive to certain drugs), administration of tumor suppressor genes, or the transfer of immunomodulatory genes to the pleural space have been proposed. [96][97][98][99] Results in the clinic are rather disheartening to date due to vector-related problems and relative inefficiency in controlling large tumor masses. However, gene therapy is most likely to be incorporated into the multimodal strategy, and when combined with nanotechnology techniques it will contribute very significantly to the improvement of treatment of malignant pleural mesothelioma in the future.…”

Validity of mesothelin in occupational medicine practice

“…For these purposes, the use of recombinant immunotoxins, monoclonal antibodies and T-cell therapy has been studied, all in potential combination with chemotherapy, as well as of antimesothelin vaccines or antibody-conjugates [46][47][48][49]. Most recently, gene-based targeted therapy considering mesothelin a key molecular target has been suggested [17]. Generally, it may be concluded that more recent studies suggest the use of SMRP levels as a suitable marker in association with the effectiveness of MM therapy and investigate the potential for further improvement of the diagnostic accuracy of SMRP levels by combining them with other markers.…”

“…In serum or pleural fluid, SMRPs may be determined by immunoenzymatic diagnostic assays, a very common example being Mesomark, as documented in numerous studies [13][14][15][16]. Although the role of mesothelin in normal and cancer cells still remains unclear [17], it has been suggested that mesothelin could be a factor promoting tumor invasion [18]. It has been shown that under normal circumstances, mesothelin is present in several human tissues, including the mesothelium and is aberrantly expressed mainly by MM but also by pancreatic cancer, ovarian cancer or some breast and lung cancers [7,12,19].…”

p53 modeling as a route to mesothelioma patients stratification and novel therapeutic identification

“…The human mesothelioma cell line Mero-14 that has wild type p53 and expresses p53 protein (Additional file 17 : Figure S2) was used as a predicted wild type p53 source and was donated by Prof. Landi (University of Pisa) [ 36 ]. Mero-14 cells were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM) (Sigma, UK) supplemented with 10% fetal bovine serum (Gibco, UK), and 1% penicillin/streptomycin (Lonza, USA) and maintained at 37 °C in a 5% CO 2 humidified atmosphere.…”