WT1 gene silencing by aerosol delivery of PEI–RNAi complexes inhibits B16-F10 lung metastases growth

Abstract

The Wilms' tumor gene 1 (WT1) is a universal tumor antigen and consequently a good therapeutic target for the development of gene therapy strategies. Earlier, we reported the in vitro efficacy of WT1 RNAi in the inhibition of B16F10 murine melanoma cell line growth. In this study, we used an aerosol system to deliver WT1 RNAi complexes, polyethyleneimine (PEI)-WT1-1 or PEI-WT1-2, to the lungs of mice with B16F10 lung metastasis. This treatment produced a statistically significant (P ¼ 0.020) reduction in the number and size of lung tumor foci, resulting in decreased lung weight and tumor index in treated mice compared with controls. The WT1 RNAi treatment also reduced the number and size of tumor blood vessels, suggesting decreased angiogenesis. Furthermore, the treated lung tissue showed cells in the tumor infiltrations undergoing apoptosis and elevated expression of the proapoptotic genes Bcl-xS and Bax, suggesting an activation of the intrinsic apoptotic pathway. Overall, WT1-1 treatment prolonged the mean survival time of tumor-bearing mice in comparison with the control and WT1-2-treated mice. Our data show that WT1 gene silencing in vivo by aerosol delivery of PEI-WT1 RNAi complexes is an effective therapeutic strategy for the treatment of lung metastases.

WT1 silencing by RNAi synergizes with chemotherapeutic agents and induces chemosensitization to doxorubicin and cisplatin in B16F10 murine melanoma cells

“…It was previously reported that the B16F10 melanoma cell line has high WT1 expression and that downregulation of this protein by RNAi is capable of inhibiting its growth [Zamora-Avila et al (27)]. To determine the LD50s to WT1-1 and WT1-2, we used a MTT assay and western blot analysis to characterize the effect of the downregulation of WT1 expression in the B16F10 cell line.…”

“…B16F10 cells were transfected with WT1-1, WT1-2 and pEGFP-N2 plasmids (Clontech) using 25 kDa of cationic polymer branched polyethylenimine (PEI). The complex PEI: DNA was performed as described by Zamora-Avila et al (27). Following 72 h, a MTT assay was performed.…”

“…RNAi technology has been used as a strategy in a number of studies in melanoma cell lines to silence genes involved in tumor progression and metastasis, including C-MYC (26) and WT1 (27). WT1 silencing significantly reduced the expression of Nestin and Zyxin genes, inhibited cell proliferation (24) and induced apoptosis by caspase-3 and poly-ADP-ribose polymerase activation (5).…”

Polymer-drug conjugates as inhalable drug delivery systems: A review

“…Pulmonary administration of PEI-RNA and WT1 (Wilms' tumor gene) complex was successfully delivered as an aerosol to the lungs of mice bearing B16-F10 melanoma metastases [60]. The PEI-RNA-WT1 complex promoted the apoptosis of B16-F10 cancer…”

HtrA2, taming the oncogenic activities of WT1

“…Indeed, clinical trials using WT1 peptide vaccines have shown effects in reducing adult leukemia cell counts and also promoting shrinkage of solid tumors. 6,9,[11][12][13] Thus, WT1 is a significant target for therapy in both pediatric and adult tumors. However, because WT1 can act as both a tumor suppressor and an oncogene, effective therapies will need to enhance WT1 activity in the former and ablate it in the latter.…”