The folate receptor (FR) is a well-validated and common target for cancer due to its high over-expression in many different cancer cells. Herein, we developed a new FR-targeting ligand (FA8) by conjugating folic acid and a cationic lipid. Owing to its favorable structural property FA8 as a ligand could be accommodated at an unusually higher molar ratio for a ligand-targeted liposome. We then encapsulated a drug-like molecule, bis-arylidene oxindole (NME2), in the targeted liposome. The resulting formulation induced potent caspase-8 up-regulation even in FR-moderately expressing melanoma cells. The NME2-associated non-targeted liposome (i.e., without FA8) or pristine NME2 could not up-regulate caspase-8. Caspase-8, an important apoptotic protein involved in the extrinsic pathway of apoptosis-signalling and inhibition of acquired drug resistance, was induced in cancer cells due to the combination treatment of liposomally associated FA8 and NME2 through the activation and subsequent cleavage of RIP-1. Consistently, in a melanoma tumor model too wherein FR is moderately expressed, significant tumour regression was obtained with this liposomal combination of FA8 and NME2. In conclusion, we demonstrate the development of a new FR-targeting ligand molecule whose higher level of inclusion (>10 mol%) in the liposomal formulation altered the mode of anticancer action of the encapsulated drug, thereby indicating a new therapeutic possibility involving FR targeted cancer treatment.

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Molecules offering simultaneous detection and killing of cancer cells are advantageous. Hybrid of cancer cell-selective, ROS generator betulinic acid and bis-arylidene oxindole with amino propyl-linker is developed. With intrinsic fluorescence, the molecule exhibited cancer cell-specific residence. Further, it generated ROS, triggered apoptosis, and exhibited potent cytotoxicity in cancer cells selectively. We demonstrate the first example and use of isatins as betulinic acid conjugate for selective detection of cancer and subsequent killing of cancer cells via apoptosis.

We report a new family of bis-arylidene oxindole derivatives that show highly selective estrogen receptor (ER)-mediated anticancer activity at low-nanomolar concentrations in ER-positive (ER+) breast cancer cells. In terms of cell growth inhibition, IC50 values for these compounds in ER+ breast cancer cells are two to three orders of magnitude lower than in ER-negative (ER-) breast cancer cells and non-cancer cells. In comparison with known bis-arylidene drugs, these compounds are at least three orders of magnitude more toxic than tamoxifen and 1.5-4-fold more toxic than 4-hydroxytamoxifen in ER+ MCF-7 cancer cells. These oxindoles inhibit ER transactivation, and their anticancer activities are inhibited in ER-depleted MCF-7 cells. Some of these nonsteroidal molecules also exhibit essential properties of selective ER down-regulation. From the development of two series of bis-arylidene oxindole-based compounds, we report a new series of anticancer agents for estrogen-responsive breast cancer.