Lysosomal P-gp targeted agent 1 (Compound 14) is an antitumor drug that targets lysosomal P-glycoprotein (Pgp). It is selectively transported to lysosomes via overexpressed Pgp, releasing nitric oxide that generates reactive oxygen species (ROS), causing lysosomal membrane permeabilization (LMP) and inducing apoptosis. This compound can overcome resistance mediated by P-glycoprotein, leading to cell cycle arrest while maintaining relatively low toxicity to normal cells. It exhibits antitumor activity by significantly inhibiting tumor growth.

Lysosomal P-gp targeted agent 1 exhibits potent anti-multidrug resistance (MDR) activity against MCF-7/ADR and A549/Taxol cells over 48 hours. It shows significant antitumor activity against MCF-7/ADR cells with an IC50 of 0.024 μM and PC-3 cells at 3.36 μM. The agent inhibits and is cytotoxic to resistant A549/Taxol cells (IC50 = 1.43 μM) and exhibits toxicity to HepG2 cells (IC50 = 6.57 μM). It displays weak inhibitory activity against MCF-7 (IC50 = 21.20 μM) and low antitumor activity against A549 cells (IC50 = 23.75 μM), while showing minimal cytotoxicity to MCF10A (IC50 = 14.32 μM) and BEAS-2B cells (IC50 = 14.80 μM). At 100 μM, the agent increases nitric oxide levels in MCF-7/ADR cells compared to MCF-7 cells, correlating with its antitumor activity. It is selectively transported into lysosomes by overexpressed P-gp and releases nitric oxide in a time-dependent manner when used at 100 nM in MCF-7/ADR and 5 μM in A549/Taxol over 1 to 3 hours. As a Pgp substrate, it does not alter Pgp expression across various concentrations (25 nM, 50 nM, 100 nM in MCF-7 and MCF-7/ADR, and 1 μM, 2 μM, 4 μM in A549, A549/Taxol for 24 hours). This agent upregulates the pro-apoptotic protein Bax and downregulates anti-apoptotic protein Bcl-2, inducing PARP1 cleavage and caspase-3 expression, thereby inducing apoptosis in MCF-7/ADR cells at 25-50 nM concentrations. It increases the total number of apoptotic cells from 8.6% to 65.9% in a dose-dependent manner over 24 hours at concentrations of 10-50 nM. Long-term efficacy is noted in MCF-7/ADR cells, where colony growth is reduced at 40 and 50 nM concentrations over 12 days. Furthermore, the agent interferes with DNA formation and causes cell cycle arrest at 20-40 nM over 24 hours.

Lysosomal P-gp targeted agent 1, administered at 1.25-5 mg/kg via intraperitoneal injection every four days for a total of 21 days, exhibits antitumor activity. It significantly reduces tumor volume and induces tumor cell death, apoptosis, or dormancy, with no detectable histological abnormalities or systemic toxicity.