Cationic lipid-conjugated bis-arylidene oxindole derivatives as broad-spectrum breast cancer-selective therapeutics

Bis-arylidene oxindoles for colorectal cancer nanotherapy

Oxindoles are potent anti-cancer agents and are also used against microbial and fungal infections and for treating neurodegenerative diseases. These oxindoles are earlier established as estrogen receptor (ER)-targeted agents for killing ER (+) cancer cells. Our previously developed bis-arylidene oxindole, Oxifen (OXF) exhibits effective targeting towards ER (+) cancer cells which has a structural resemblance with tamoxifen. Herein, we have designed and synthesized few structural analogues of OXF such as BPYOX, ACPOX and ACPOXF to examine its cytotoxicity in different cancer as well as non-cancer cell lines and its potential to form self- aggregates in aqueous solution. Among these series of molecules, ACPOXF showed maximum toxicity in colorectal cancer cell line which are ER (-) but it also kills non-cancer cell line HEK-293, thereby reducing its cancer cell selectivity. Incidentally, ACPOXF exhibits self-aggregation, without the help of a co-lipid with nanometric size in aqueous solution. ACPOXF self-aggregate was co-formulated with glucocorticoid receptor (GR) synthetic ligand, dexamethasone (Dex) (called, ACPOXF-Dex aggregate) which could selectively kill ER (-) colorectal cancer cells and also could increase survivability of colon-tumour bearing mice. ACPOXF-Dex induced ROS up-regulation followed by apoptosis through expression of caspase-3. Further, we observed upregulation of antiproliferative factor, p53 and epithelial-to-mesenchymal (EMT) reversal marker E-cadherin in tumour mass. In conclusion, a typical structural modification in ER-targeting Oxifen moiety resulted in its self-aggregation that enabled it to carry a GR-ligand, thus broadening its selective antitumor property especially as colon cancer therapeutics.

Progesterone-Cationic Lipid Conjugate-Based Self-Aggregates for Cancer Cell-Selective Uptake through Macropinocytosis and the Antitumour Effect

Progesterone (PR) is an endogenous steroid hormone that activates the progesterone receptor (PgR) and is known to play a critical role in cancer progression. Herein, we report the development of cationic lipid-conjugated PR derivatives by covalently conjugating progesterone with cationic lipids of varying hydrocarbon chain lengths (n = 6-18) through a succinate linker. Cytotoxicity studies performed on eight different cancer cell lines reveal that PR10, one of the lead derivatives, exerts notable toxicity (IC₅₀ = 4-12 μM) in cancer cells irrespective of their PgR expression status and remains largely nontoxic to noncancerous cells. Mechanistic studies show that PR10 induces G2/M-phase cell cycle arrest in cancer cells, leading to apoptosis and cell death by inhibiting the PI3K/AKT cell survival pathway and p53 upregulation. Further, in vivo study shows that PR10 treatment significantly reduces melanoma tumor growth and prolongs the overall survival of melanoma tumor-bearing C57BL/6J mice. Interestingly, PR10 readily forms stable self-aggregates of ∼190 nm size in an aqueous environment and exhibits selective uptake into cancerous cell lines. In vitro uptake mechanism studies in various cell lines (cancerous cell lines B16F10, MCF7, PC3, and noncancerous cell line HEK293) using endocytosis inhibition proves that PR10 nanoaggregates enter selectively into the cancer cells predominantly using macropinocytosis and/or caveolae-mediated endocytosis. Overall, this study highlights the development of a self-aggregating cationic derivative of progesterone with anticancer activity, and its cancer cell-selective accumulation in nanoaggregate form holds great potential in the field of targeted drug delivery.