hti-286 and Urinary-Bladder-Neoplasms

HTI-286 is a fully synthetic analogue of the natural tripeptide hemiasterlin that inhibits tubulin polymerization and has strong cytotoxic potential. In this study, we evaluate the inhibitory effects of HTI-286 on human bladder cancer growth, both in vitro and as an intravesical agent in an orthotopic murine model.. Various bladder cancer cell lines were treated with HTI-286 and mitomycin C (MMC) in vitro. Human KU-7 bladder tumor cells that stably express firefly luciferase were inoculated in female nude mice by intravesical instillation and quantified using bioluminescence imaging. Mice with established KU-7-luc tumors were given HTI-286 or MMC intravesically twice a week for 2 h. Pharmacokinetic data was obtained using high-performance liquid chromatography-mass spectrometry analyses.. In vitro, HTI-286 was a potent inhibitor of proliferation in all tested cell lines and induced marked increases in apoptosis of KU-7-luc cells even after brief exposure. In vivo, HTI-286 significantly delayed cancer growth of bladder tumors in a dose-dependent fashion. HTI-286, at a concentration of 0.2 mg/mL, had comparable strong cytotoxicity as 2.0 mg/mL of MMC. The estimated systemic bioavailability of intravesically given HTI-286 was 1.5% to 2.1% of the initial dose.. Intravesical HTI-286 instillation therapy showed promising antitumor activity and minimal toxicity in an orthotopic mouse model of high-grade bladder cancer. These findings provide preclinical proof-of-principle for HTI-286 as an intravesical therapy for nonmuscle-invasive bladder cancer and warrant further evaluation of efficacy and safety in early-phase clinical trials.

Topics: Administration, Intravesical; Animals; Antibiotics, Antineoplastic; Apoptosis; Cell Cycle; Cell Proliferation; Drug Therapy, Combination; Female; Humans; Luminescence; Mice; Mice, Nude; Mitomycin; Oligopeptides; Tumor Cells, Cultured; Urinary Bladder Neoplasms; Xenograft Model Antitumor Assays

Clinical results of current intravesical chemotherapeutics are insufficient, and novel and safe intravesical options for high-risk bladder cancer are required to prevent both recurrence and progression. In this study, we show promising efficacy of intravesical combination treatment using antisense oligonucleotides targeting heat shock protein-27 (Hsp27; OGX427) with HTI-286, a synthetic analogue of the marine sponge product hemiasterlin. The expression of Hsp27 in bladder cancer was examined using tissue microarray analysis. Then, four bladder cancer cell lines were screened for combination effects of OGX427 with HTI-286, and the molecular mechanisms underlying the synergic effect were analyzed. Chemosensitivity against HTI-286 was also compared between mock-transfected T24 (T24 mock) cells and Hsp27-overexpressing T24 (T24 Hsp27) cells. Furthermore, in vivo data were obtained in a bioluminescent orthotopic murine model of high-grade disease. Hsp27 is expressed at higher levels in bladder cancers compared with normal bladder epithelium. OGX427 significantly enhanced cytotoxicity of HTI-286. Combination treatment induced Akt inactivation and Bcl-2 down-regulation. T24 Hsp27 cells were more resistant to HTI-286 than T24 mock cells and showed stronger Akt activation after HTI-286 treatment. The protective effect of Hsp27 against HTI-286 was suppressed by LY294002, a phosphatidylinositol 3-kinase inhibitor, indicating that Hsp27-Akt interactions are key mechanisms to enhance chemosensitivity via OGX427. Intravesical combination therapy effectively inhibited orthotopic tumor growth without toxic side effects. Our results suggest that OGX427 enhances cytotoxicity of HTI-286 through Akt inactivation and provide strong preclinical proof-of-principle for intravesical administration of OGX427 in combination with HTI-286 for high-grade bladder cancer.

Topics: Administration, Intravesical; Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Female; HSP27 Heat-Shock Proteins; Humans; Oligonucleotides, Antisense; Oligopeptides; Urinary Bladder Neoplasms