Molecular characterization of highly tumorigenic cell lines used in a xenograph model to investigate cellular therapy for the treatment of refractory ovarian cancer

Abstract

e16516 Background: Because current therapies for ovarian cancer (OC) have little impact on the long-term survival, there is a compelling need to develop innovative strategies. Our aim was to characterize OC cell lines which can be utilized to test cellular therapy in combination with cytokines or chemotherapies to elicit a graph versus tumor response to treat refractory OC patients. Methods: SKOV-3-RFP, a red fluorescent protein (RFP) expressing line, was passaged through nude mice to create more tumorigenic lines compared to parental SKOV-3 cells. Three SKOV-3-derived lines were established and characterized for IFNα-2b sensitivity, E-cadherinand CCN1gene expression, and STAT3 activation. The cells were grown in the presence of IFNα-2b to determine proliferative effects. Tumors were harvested when mice became moribund; ascitic fluid (AF) and solid tumor (ST) tissue were snap-frozen. Expression of E-cadherinand CCN1, which have been implicated to play role(s) in OC pathobiology, were analyzed in ST harvested from the mice and from SKOV3-derived lines (SKOV3-RFP, AF1, AF2, and AF3). We investigated the activation status in the SKOV3-derived cells of STAT3, which has been associated with malignant transformation and tumor progression. Results: Parental SKOV3-RFP cells when injected at a dose of 5x106 gave a tumor incidence of 4/6 in 14 weeks. AF1 and AF2, when injected at a dose of 1x106 resulted in 100% tumor incidence in 5-weeks (n = 5). These two lines were also more resistant to IFNα-2b compared to RFP. All SKOV3-derived lines and ST expressed E-cadherin by RT-PCR. None of the SKOV3-derived lines expressed CCN1; however, one of the two AF1 ST tested expressed CCN1. Both AF2 ST evaluated showed weak expression of CCN1. In vitro DNA-binding with electrophoretic mobility shift assay (EMSA), showed AF1 and AF3 cells harbor constitutively-active STAT3, whereas the RFP line does not. Conclusions: The SKOV3-derived lines that we developed will be a better model to test novel OC treatment regiments because these lines exhibit increased resistance to IFNα-2b, are more tumorigenic in a xenograph model, show aberrant STAT3 activation, and tumors harvested from these lines express genes that make these lines more aggressive. No significant financial relationships to disclose.