Abstract
BackgroundMelanoma represents one of the most aggressive and therapeutically challenging malignancies as it often gives rise to metastases and develops resistance to classical chemotherapeutic agents. Although diverse therapies have been generated, no major improvement of the patient prognosis has been noticed. One promising alternative to the conventional therapeutic approaches currently available is the inactivation of proteins essential for survival and/or progression of melanomas by means of RNA interference. Survivin and cyclin B1, both involved in cell survival and proliferation and frequently deregulated in human cancers, are good candidate target genes for siRNA mediated therapeutics.MethodsWe used our newly developed sticky siRNA-based technology delivered with linear polyethyleneimine (PEI) to inhibit the expression of survivin and cyclin B1 both in vitro and in vivo, and addressed the effect of this inhibition on B16-F10 murine melanoma tumor development.ResultsWe confirm that survivin and cyclin B1 downregulation through a RNA interference mechanism induces a blockage of the cell cycle as well as impaired proliferation of B16-F10 cells in vitro. Most importantly, PEI-mediated systemic delivery of sticky siRNAs against survivin and cyclin B1 efficiently blocks growth of established subcutaneaous B16-F10 tumors as well as formation and dissemination of melanoma lung metastases. In addition, we highlight that inhibition of survivin expression increases the effect of doxorubicin on lung B16-F10 metastasis growth inhibition.ConclusionPEI-mediated delivery of sticky siRNAs targeting genes involved in tumor progression such as survivin and cyclin B1, either alone or in combination with chemotherapeutic drugs, represents a promising strategy for melanoma treatment.
Highlights
Melanoma represents one of the most aggressive and therapeutically challenging malignancies as it often gives rise to metastases and develops resistance to classical chemotherapeutic agents
Transfection of B16-F10 cells with jetPEI® and different concentrations of specific Sticky siRNA (ssiRNA) ranging from 25 to 100 nM was performed and all led to a significant reduction of cyclin B1 and survivin mRNA
We looked at the MITF mRNA level in lungs of ssiRNA-treated mice, and observed a significant diminution after either survivin or cyclin B1 ssiRNA systemic treatment compared to the level of MITF present in lungs of glucose or negative control ssiRNA treated mice (65 and 56% inhibition compared to negative control ssiRNA, respectively, Figure 5b)
Summary
Melanoma represents one of the most aggressive and therapeutically challenging malignancies as it often gives rise to metastases and develops resistance to classical chemotherapeutic agents. Various approaches involving molecular inhibitors have been developed to inhibit its expression in tumor cells [6,13,14,15,16,17] Another potential therapeutic target for cancer treatment is represented by cyclin B1, the regulatory subunit of cyclin-dependent kinase 1 (cdk1), which plays a pivotal role in the transition of the cell cycle from G2 phase to mitosis [18]. Several studies have demonstrated its clinical significance as a poor prognosis factor for several cancer types [24,25,26,27], including melanoma [28], and cyclin B1 overexpression is responsible for radiotherapy resistance in different tumors [29,30,31]
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