Curcumin, an ingredient of turmeric, exhibits a variety of biological activities such as anti-inflammatory, anti-atherosclerotic, anti-proliferative, anti-oxidant, anti-cancer and anti-metastatic. It is a highly pleiotropic molecule that inhibits cell proliferation and induces apoptosis in cancer cells. Despite its imperative biological activities, chemical instability, photo-instability and poor bioavailability limits its utilization as an effective therapeutic agent. Therefore, enhancing the bioavailability of curcumin may improve its therapeutic index for clinical setting. In the present study, we have conjugated curcumin with a biodegradable polymer Poly (D, L-lactic-co-glycolic acid) and evaluated its apoptotic potential in human colon carcinoma cells (HCT 116). The results show that curcumin-PLGA conjugate efficiently inhibits cell proliferation and cell survival in human colon carcinoma cells as compared to native curcumin. Additionally, curcumin conjugated with PLGA shows improved cellular uptake and exhibits controlled release at physiological pH as compared to native curcumin. The curcumin-PLGA conjugate efficiently activates the cascade of caspases and promotes intrinsic apoptotic signaling. Thus, the results suggest that conjugation potentiates the sustainability, anti-proliferative and apoptotic activity of curcumin. This approach could be a promising strategy to improve the therapeutic index of cancer therapy.

The receptor for advanced glycation end-products (RAGE) is a multiligand member of the immunoglobulin superfamily, which plays an important role in maintaining cellular homeostasis. It is normally expressed on immune cells, including macrophages, monocytes, dendritic cells and T cells to maintain homeostasis, but highly upregulated at sites of vascular pathology. Accumulating evidence suggest that the elevated expression of RAGE and its ligand HMGB-1 was found in various types of cancer. The accumulation of RAGE and its ligand high-mobility group box proteins-1 (HMGB1) activates complex signaling network for cell survival and evades apoptosis. Therefore, targeting the RAGE-mediated signaling could be the promising strategies for the therapeutic potential of cancer. This study was aimed to examine the biological potential of quercetin on the regulation of RAGE-and HMGB1-mediated activation of NF-jB and induction of apoptotic cell death in MCF-7 cells. Our findings demonstrate that quercetin inhibits the expression of RAGE and HMGB1 in MCF-7 cells. In addition, quercetin protects necrotic insult and augments apoptosis in MCF-7 cells. Taken together, these results suggest that quercetin plays an important role in modulating RAGE and HMGB1 signaling and induces apoptotic cell death in MCF-7 cells.