Targeting Phosphatidylinositol-3-Kinase Signaling with Simultaneous DNA Damage in Cancer Cells by Cholesterol Based Chimeric Nanoparticle

Introduction: Phosphatidylinositol-3-kinase (PI3K) signaling has been a major target as it is found to be mutated and over expressed in many types of cancers. PI3K inhibition alone by small molecules often fails to offer... [ view full abstract ]

Introduction: Phosphatidylinositol-3-kinase (PI3K) signaling has been a major target as it is found to be mutated and over expressed in many types of cancers. PI3K inhibition alone by small molecules often fails to offer effective therapy because of emergence of drug resistance. Recent studies revealed that inhibiting singling pathways with simultaneous DNA damage is effective to combat cancer. However, targeting PI3K signaling with small molecules in combination with DNA damaging drugs is challenging as it leads to severe side effects due to nonspecific interactions in cancer patients. To overcome this we have synthesized chimeric nanoparticles (CNPs).

Methods: Cholesterol drug conjugates were synthesized and conjugates 3, 4, and 6 (Fig.1) were mixed with phosphatidylcholine and DSPE-PEG and synthesized  CNPs by lipid film formation, hydration, and extrusion method. CNPs were characterized for their size, shape, and morphology  by dynamic light scattering (DLS), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Drug loading and release kinetics were assessed by UV- visible spectroscopy.  To demonstrate the efficacy of these CNPs in inhibiting tumor cell growth in different cancer cells, different in-vitro cell experiments were performed.

Results and Discussions: CNPs have shown simultaneous loading of PI103, cisplatin and doxorubicin in a controlled ratiometric manner also demonstrated increased release of all three drugs through sustainable manner over 120 h at pH = 5.5 compared to neutral pH. The CNPs showed much improved in vitro cytotoxicity in HeLa, HL60, MCF7, and MDAMB- 231 cancer cells compared to a free drug cocktail at 24 and 48 h also induced apoptosis. Confocal imaging revealed that these CNPs were internalized into cells through endocytosis in a time dependent mode over 6 h in HeLa, MDA-MB-231, and MCF-7 cells. These CNPs exhibited their efficacy by damaging DNA and inhibiting Akt as a downstream modulator of PI3K signaling in HeLa cervical cancer cells. To conclude, these CNPs have the potential to open up new directions in next-generation nanomedicine by targeting multiple oncogenic signaling pathways with simultaneous induction of DNA damage for the augmented therapeutic outcome by reducing off-target toxicity and overcoming drug resistance.