Tangeretin derivative, 5-acetyloxy-6,7,8,4′-tetramethoxyflavone induces G2/M arrest, apoptosis and autophagy in human non-small cell lung cancer cells in vitro and in vivo

Abstract

Tangeretin, a major phytochemicals in tangerine peels--an important Chinese herb, has been found to have anti-carcinogenic properties. To improve bioavailability and increase potency of tangeretin, its derivative, 5-acetyloxy-6,7,8,4'-tetramethoxyflavone (5-AcTMF), has been synthesized and shown potent inhibition of proliferation activity against human breast and leukemia cancer cell lines. In this study, we have further investigated the anticancer effects of 5-AcTMF on CL1-5 non-small cell lung cancer cells (NSCLC) both in vitro and in vivo and demonstrated that 5-AcTMF effectively inhibited cancer cell proliferation, induced G2/M-phase arrest associated with cdc2 and CDC25c and increased in the apoptotic cells associated with caspase activation, down regulation of Bcl-2, XIAP and Survivn, inducing release of cytochrome c into the cytosol and disruption of mitochondrial membrane potential. We also found that 5-AcTMF treatment of CL1-5 activated autophagy, indicated by triggered autophagosome formation and increased LC3-II levels and formation of LC3 puncta. Moreover, we also found that 5-AcTMF lowered phophoatidylinositol 3-kinase/AKT/mTOR signaling pathway. Over-expression of AKT by AKT cDNA transfection decreased 5-AcTMF mediated apoptosis and autophagy, supporting the induction of apoptosis and autophagy by inhibition of AKT pathway. In an animal study, 5-AcTMF effectively delayed tumor growth in a nude mouse model of CL1-5 xenografts without observed adverse effect. Immunohistochemistry Analysis indicated that 5-AcTMF induced CL1-5 cell apoptosis and autophagy in vivo. Taken together, these data demonstrate that 5-AcTMF is a novel small molecule agent that can inhibit NSCLC cell proliferation, and induce G(2)/M phase arrest and via the mitochondrial apoptotic pathway and autophagy.

Nutraceuticals: Curative Integrative Cancer Treatment

“…Nobiletin modulates hypoxia-TGFinduced epithelial-mesenchymal transition, inhibits notch-1 and TGF-β1/Smad3 signaling, while promoting microRNA-200b re-expression [51]. In vitro, the tangeretin derivative 5-AcTMF is antiproliferative to MCF-7, the U226 myeloma and CL1-5 NSCLC cell lines [52]. The tangeretin derivative 5-demethyltangeretin is more cytotoxic than tangeretin against A549, H460, and HI299 cell lines, with 79, 57 and 56 fold lower IC50 respectively [51].…”

“…Apigenin and luteolin have other sources, including celery and parsley [43]. Polymethoxyflavones (PMF) are unique to citrus species' peels, thus used in TCM [52]. Tangeretin, a tangerine derived PMF is anti-inflammatory in microglial cells, suppresses adipocyte storage of triglycerides, and induces G1 arrest or apoptosis in cancer cells [52].…”

“…Polymethoxyflavones (PMF) are unique to citrus species' peels, thus used in TCM [52]. Tangeretin, a tangerine derived PMF is anti-inflammatory in microglial cells, suppresses adipocyte storage of triglycerides, and induces G1 arrest or apoptosis in cancer cells [52]. Tangeretin and nobiletin (another PMF) are antiproliferative to A549, MCF-7 and MDA-MB-435 breast cancer, HT-29 colon cancer, and HL-60 leukemia cell lines [51,53,54].…”

“…C. maculatum ethanolic extract should undergo in vivo murine trials against A375, A549, HeLa, HepG2, and WRL68 cell lines, to assess efficacy and tolerability. Tangeretin, nobiletin and 5-AcTMF should be further trialed for breast, colon, leukemia, myeloma, and NSCLC treatment [52][53][54]. BITC should be further studied for breast cancer treatment [82].…”

“…In this light, quercetin is being studied as an enhancer for green tea polyphenol bioavailability and activity [98]. Pro-drug derivatives may need to be developed [52]. Similarly, with synthetic analogs, bioavailability enhancement may be possible without adverse effects as displayed by CYD-6-28 [69].…”