EGCG: The antioxidant powerhouse in lung cancer management and chemotherapy enhancement

Lung cancer is the main cause of cancer-related deaths throughout the world. Its treatment involves intensive cycles of chemotherapy and radiotherapy, which are associated with serious adverse effects. EGCG, an active component of green tea/white tea, regulates cell molecular pathways of apoptosis, angiogenesis, proliferation, differentiation, and self-renewal ability of cancer stem cells. It also acts as a pro-oxidant that can cause cell death in cancer cells via apoptosis. It can control lung carcinogenesis by altering the molecules involved in multiple signal transduction pathways like Ras-GTPase, ERK, COX2, VEGF, and protein kinases. Moreover, it can also affect other signalling molecules or pathways such as DNMT1, MAPK, NF-κB, Bcl/Bax, HIF-1α, EGFR, Akt/PI3, Wnt/β-catenin, caspases, NEAT1, TGF-β, HDGF, and CLOCK. Recent studies on cell lines and animals have focused on the role of EGCG in enhancing the efficacy of chemotherapeutic drugs and reducing their adverse effects. The low bioavailability and rapid metabolism of EGCG can act as a hurdle in the translation of this agent from lab to bedside. The uses of synthetic agents such as COMT inhibitors and nano-drug delivery tools have been shown to enhance the plasma levels of EGCG and its cancer preventive and therapeutic ability.