Antitumor effect of nanosponge-encapsulated camptothecin in human prostate tumors

ANTITUMOR EFFECT OF NANOSPONGE-ENCAPSULATED CAMPTOTHECIN IN HUMAN PROSTATE TUMORS. 1Rosalba Minelli, 1Roberta Cavalli, 2 Sergio Occhipinti, 3Luca Gigliotti, 1Roberto Fantozzi, 2Mirella Giovarelli, 3Umberto Dianzani and 1Chiara Dianzani 1Departement of Science and Pharmaceutical Technology, University of Turin, Turin, Italy; 2Department of Medicine and Experimental Oncology, University of Turin, Turin, Italy; 3Interdisciplinary Research Center of Autoimmune Diseases (IRCAD) and Department of Health Sciences, “A. Avogadro” University of Eastern Piedmont, Novara, Italy Camptothecin (CPT) is a pentacyclic quinoline alkaloid that exerts a potent DNA Topoisomerase I inhibitor effect with anti-tumor activity in hematological and solid tumors. However, its clinical use is prevented by major limitations such as poor solubility and hydrolysis. Some camptothecin analogs, either semi-synthetic or synthetic such as topotecan and irinotecan, have been used in cancer therapy. An alternative approach is to take advantage by nanomedicine that has enormous potentials in improving drug availability, stability and decreasing side effects. In this line, here, we evaluated whether β-cyclodextrin-based nanosponge carriers can overcome CPT chemical disadvantages and improve the in vitro anti-tumor efficacy in androgen refractory (DU145 and PC-3 cell lines) and androgen sensitive (LNCaP cell line) models of prostate cancer. HPLC analysis, performed on the cell pellet after treatment with CPT-loaded β-cyclodextrin nanosponge (CN-CPT), revealed that CPT concentration increased over time indicating a prolonged release of the drug. Moreover, CN-CPT inhibited Topoisomerase I activity, induced DNA damage and cell cycle arrest, indicating that the CN-CPT formulation does not affect activity of the drug. CN-CPT exerted an increased anti-tumor activity, in both cell line models, as compared to CPT. Moreover, Annexin V/Propidium Iodide staining showed an induction of cell death at low concentrations that were not effective for CPT. LNCaP cells were less sensitive to both CPT and CN-CPT, than PC-3 and DU145 cells, but CN-CPT always exerted higher antiproliferative activity and DNA damage ability than CPT. Moreover in LNCaP cells, CN-CPT treatment inhibited expression of the androgen receptor at doses that were ineffective for CPT. To evaluate the antimetastatic activity of CPT, in vitro experiments of tumor cell adhesion to HUVECs and cell motility were performed. Results showed that CN-CPT was effective at lower doses than CPT and irinotecan in inhibiting cell adhesion and motility. HUVEC treatment with CPT or CN-CPT did not modulate surface expression of adhesion molecules. Finally, the anti-tumor effect of CN-CPT was tested in vivo using PC3-xenograft SCID/beige mice and results confirmed a significant improvement of antitumoral activity of CN-CPT as compared to CPT. Taken together, these results support the use of the β-cyclodextrin nanosponge technology to deliver anticancer drugs for the treatment of both androgen sensitive and refractory prostate cancers.