Targeted delivery of topotecan via folic acid functionalized phycocyanin nanoparticles for ovarian cancer.

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Background: Ovarian cancer remains the deadliest gynecologic malignancy due to late-stage diagnosis and frequent treatment resistance. The aim of the present work was to evaluate improved therapeutic efficacy of topotecan with regards to combating drug resistance in ovarian cancer cells. Methods: Folic acid tagged topotecan loaded phycocyanin nanoparticles were prepared by modified desolvation process. Nanoformulation was characterized in terms of size and shape by electron microscopy. Surface modification was observed by FTIR. The release kinetics of nanoformulation in PBS solutions at pH 7.4 and pH 5.5 was studied to mimic the plasma and lysosomal environment in vitro. The anti-cancer activity was investigated in vitro by MTT assay in resistant (PA-1R) as well as sensitive (PA-1) ovarian cancer cell line. pK and acute toxicity studies were also performed in female mice and safety profiling of nanoformulation was performed by histopathological study in vital organs. Apoptosis involvement was studied using ELISA for measuring anti and pro apoptotic proteins. Expression levels of proteins like ABCG2, ABCB1, PTPRK were studied through RT-PCR assay. Results: Nanoformulation revealed spherical nanoparticles with 72-80 nm size range. The release rate of topotecan from nanoformulation was significantly faster at pH 5.5 throughout 96-h release period than at pH 7.4. Cytotoxic effect of nanoformulation was more pronounced against PA-1R cells as compared to topotecan alone. This was substantiated by various other studies like migration assay and 3D spheroid formation restriction activity. There was 2 fold increase in BAX and almost 7 fold increase in caspase 3 activity after 12 h of incubation. Likewise 4.5 fold decrease in Bcl-2 levels were observed. Altered levels of ABCB1 and PTPRK were modulated by nanoformulation. ABCB1 showed 6 fold increase in nanoformulation treated PA-1R cells as compared to 4 fold increase in case of parent topotecan. Similarly, 2 fold change in PTPRK was observed in nanoformulation treated resistant cells. Although ABCG2 levels showed similar pattern, however difference was not very significant. No toxicity was observed in terms of body weight, feeding habits during 14 days observation period while performing acute toxicity assay, which was confirmed by histopathological analysis. Conclusions: This preliminary characterization of the formulation shows a new insight for improving the therapeutic efficacy of topotecan, by adopting new delivery strategies, using phycocyanin nanoparticles.