Curcumin-docetaxel co-loaded nanosuspension for enhanced anti-breast cancer activity.

PURPOSE: A curcumin-docetaxel co-loaded nanosuspension with increased anti-breast cancer activity was developed. Curcumin is a potential anticancer agent with p-glycoprotein (p-gp) inhibiting activity may be co-administered with docetaxel as a nanosuspension to enhance its anticancer effect by increasing the oral bioavailability and decreasing drug efflux. METHODS: Nanosuspensions of curcumin and docetaxel were prepared by precipitation-homozenisation technique and evaluated for particle size, polydispersity, zeta potential and drug release. The in vitro MTT assay was conducted using MCF-7 for anti-breast cancer activity. The in vivo biodistribution by radiolabeling and tumor inhibition study was conducted in mice. RESULTS: Homogenous nanosuspensions of 80 ± 20 nm were obtained with increased solubility. The drugs as nanosuspensions showed higher cytotoxicity on MCF-7 cell line compared to their suspensions due to the increased in vitro cellular uptake. Due to this increased solubility, sensitization of tumor cells and inhibition of p-gp the in-vivo results showed greater tumor inhibition rate of up to 70% in MCF-7 treated mice. Histopathological results showed higher apoptotic activity and reduced level of angiogenesis. CONCLUSIONS: The in vitro and in vivo study of the nanosuspensions has shown that Co-administration of Curcumin as a p-gp inhibitor with docetaxel may have the potential to increase the anti-breast cancer efficacy of both drugs.

Autoregulation and heterogeneity in expression of human Cripto-1.

Cripto-1 (CR-1) is involved in various processes in embryonic development and cancer. Multiple pathways regulate CR-1 expression. Our present work demonstrates a possible positive feedback circuit where CR-1 induces its own expression. Using U-87 MG cells treated with exogenous CR-1, we show that such induction involves ALK4/SMAD2/3 pathway. Stochasticity in gene expression gives rise to heterogeneity in expression in genetically identical cells. Positive feedback increases such heterogeneity and often gives rise to two subpopulations of cells, having higher and lower expression of a gene. Using flow cytometry, we show that U-87 MG cells have a minuscule subpopulation with detectable expression of CR-1. Induction of CR-1 expression, by exogenous CR-1, increases the size of this CR-1 positive subpopulation. However, even at very high dose, most of the cells remain CR-1 negative. We show that population behavior of CR-1 induction has a signature similar to bimodal expression expected in a transcriptional circuit with positive feedback. We further show that treatment of U-87 MG cells with CR-1 leads to higher expression of drug efflux protein MDR-1 in the CR-1 positive subpopulation, indicating correlated induction of these two proteins. Positive feedback driven heterogeneity in expression of CR-1 may play crucial role in phenotypic diversification of cancer cells.

Human recombinant Cripto-1 increases doubling time and reduces proliferation of HeLa cells independent of pro-proliferation pathways.

Human oncofetal protein Cripto-1 (CR-1) is overexpressed in many types of cancers. CR-1 binds to cell surface Glypican-1 to activate Erk1/2 MAPK and Akt pathways leading to cell proliferation. However, we show that treatment with recombinant CR-1 reduces proliferation of HeLa cells by increasing the doubling time without triggering cell death or cell cycle arrest. Using a comparative study with U-87 MG cells, we show that the pro-proliferative pathway of CR-1 is not effective in HeLa cells due to lower expression of Glypican-1. Further we show that treatment with recombinant CR-1 increases PTEN in HeLa cells leading to downregulation of PI3K/Akt pathway. The anti-proliferative effect gets potentiated when the pro-proliferative pathway is blocked.