Macro phage stimulating protein activates the RON re ceptor tyrosine kinase, which regulates several activities of epithelial cells. The MSP RON pathway plays also a role in epithelial carcinogenesis and RON is found over expressed in many breast, colon, and pancreatic tumors. As activation of the MSP RON pathway directs invasive growth, it can be inferred that the decreased expression of genes involved in this pathway in SiHaCDV versus SiHaparental will be translated in a re duced tumorigenicity in vivo. In the context of developing CDV as an anti cancer drug, our findings have therapeuticbiological signifi cance since we showed that acquisition of CDV resistance is expected to result in a reduced malignant phenotype. Today, no evidence for the development of resistance to CDV in the treatment of HPV associated lesions has been reported.
Conclusions Although several studies have characterized CDV resistant selelck kinase inhibitor herpes, and poxviruses, this is the first study reporting the in vivo characterization of tumor cells selected for CDV resistance. Similarly to a reduced pathogenicity described for CDV resistant viruses, de velopment of resistance to CDV as an anti cancer drug was associated with a marked reduction in pathogenicity. The present study contributes to our understanding on how the alterations in inflammatory response following acquisition of CDV resistance while not causing the resistant phenotype per se affect the tumor microenvironment in vivo and contribute to a reduced pathogenicity and tumorigenicity. Methods Compounds Cidofovir, PMEG and cPr PMEDAP {cyclo propyl 9 was obtained from Sigma. Cells SiHa cells, HPV16 positive cervical carcinoma, were maintained in Dulbeccos modified Eagles medium supplemented with 10% fetal calf serum.
SiHa cells resistant to CDV were selected PD0325901 clinical trial by passing the cells under increasing drug concentration for approxi mately 45 passages during a 2 years time. The parental SiHa cells and those selected for re sistance to CDV were denoted SiHaparental and SiHaCDV, respectively. In order to demonstrate that both cell lines were related, short tandem repeat analysis was performed at the Forensic Laboratory of UZ Leuven. Despite some small alterations fol lowing long term culturing of the cells, the STR analysis confirmed that SiHaparental and SiHaCDV were related and thus that the resistant cell line is indeed a derivative of the parental cell line. Drug antiproliferative effects and in vitro growth rate Inhibition of SiHaparental and SiHaCDV growth was deter mined following different times of incubation with the compounds. Compounds were tested at different con centrations in a range of 0. 63 uM 634. 7 uM for CDV, 0.