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.

Background: Previous reports related the presence of mouse mammary tumor virus (MMTV)-like gene sequences to human breast carcinoma. The aim of this study was to determine whether MMTV-like env gene sequences are present in breast cancer samples of Mexican women and in breast and lung cancer cell lines. Methods: Using specific primers for MMTV, we tested 3 breast cancer cell lines, 4 non-small lung cancer cell lines and 119 breast cancer samples from Mexican women. Results: MMTV-like gene sequences were amplified in the lung cancer cell INER-51, but not in the MCF-7 cell line that has been used as a positive control in other reports and in 5 of 119 (4.2%) breast cancer biopsy tissues. Furthermore, the identity of sequences of PCR products from INER-51 and a breast cancer-positive sample are 98 and 99% when compared with the env region of MMTV (GenBank accession No. AY161347). Conclusion: These results indicate that MMTV-like gene sequences are present in the Mexican population.

The Wilms' tumor protein 1 (WT1) is essential for tumor cell proliferation and is highly expressed in various hematological and solid malignancies including human malignant melanoma. We investigated whether WT1 expression is essential for growth in the B16F10 murine melanoma cell line. Toward this end, we examined WT1 protein expression and WT1 isoforms (17AA+/17AA-, KTS+/KTS-) in this cell line. WT1 was silenced by two RNA interference constructs, designated WT1-1 and WT1-2. RNA interference-mediated reduction of WT1 protein expression significantly inhibited B16F10 cell viability. Loss of WT1 also increased caspase-3 and poly-ADP-ribose polymerase activation, as well as apoptotic body formation, chromatin condensation, and DNA fragmentation. Together, these findings implicate decreased WT1 protein levels in the induction of apoptosis. These results imply that WT1 plays a distinct role in B16F10 melanoma growth.

These observations suggest that IMMUNEPOTENT CRP can be used to suppress growth and metastasis by using targeting proteins such as VEGF.

Abstract. The Wilm's tumor gene (WT1), encoding a transcription factor that modulates the expression of certain genes that are involved in proliferation and apoptosis, is overexpressed in numerous solid tumors. WT1 is important for cell proliferation and in the diagnosis of melanoma. The objectives of this study were to investigate whether WT1 silencing is capable of synergizing with chemotherapeutic agents and whether this silencing is capable of sensitizing cancer cells to doxorubicin and cisplatin in the B16F10 murine melanoma cell line. In the present study, B16F10 cells were simultaneously treated with median lethal doses (LD50s) of WT1-1 or WT1-2 small hairpin RNAs (shRNAs) and chemotherapeutic agents. A total of 24 h posttransfection, a [3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide assay] MTT assay was performed. To determine whether shRNA interference (shRNAi) is capable of sensitizing B16F10 cells to chemotherapeutic agents, cells were transfected with an LD50 of each of the recombinant plasmids, treated with varying concentrations of doxorubicin or cisplatin 24 h post-transfection, and analyzed 48 h later for inhibition of cell proliferation using the MTT assay. We observed that WT1-RNAi and the two chemotherapeutic agents acted synergistically to inhibit B16F10 cell proliferation. The greatest inhibition of cell proliferation was observed with the WT1-2/cisplatin (91%) and WT1-1/cisplatin combinations (85%). WT1 silencing using shRNAi induced the chemosensitization of cells to doxorubicin and cisplatin, with the greatest inhibition (85%) of cell proliferation being observed in the cells treated with the WT1-2/cisplatin 6 ng/µl combination. Our results provide direct evidence that WT1 gene silencing has a synergistic effect with chemotherapeutic drugs and sensitizes B16F10 melanoma cells to doxorubicin and cisplatin. This suggests that these combination strategies are potentially utilized in melanoma therapy.