Isoliquiritigenin (ISL), a member of the flavonoids, is known to have anti-tumor activity in vitro and in vivo. The effect of ISL on reprogramming in cancer cells, however, remains elusive. In this study, we investigated the effect of ISL on reprogramming in human melanoma A375 cells. ISL (15 μg/ml) significantly inhibited A375 cell proliferation, anchorage independent cell proliferation and G2/M cell cycle arrest after ISL exposure for 24 h. However, there were no significant changes in apoptosis rate. Terminal differentiation indicators (melanin content, melanogenesis mRNA expression, tyrosinase (TYR) activity) were all up-regulated by ISL treatment. In ISL-treated cells, glucose uptake, lactate levels and mRNA expression levels of GLUT1 and HK2 were significantly decreased, and accompanied by an increase in O2 consumption rate (OCR) and adenosine triphosphate (ATP) deficiency. Protein expression levels of mTORC2-AKT-GSK3β signaling pathway components (mTOR, p-mTOR, RICTOR, p-AKT, p-GSK3β) decreased significantly after ISL treatment. Co-treatment of ISL and the mTOR-specific inhibitor Ku-0063794 had a synergistic effect on the inhibition of proliferation, and increased melanin content and TYR activity. Glucose uptake and lactate levels decreased more significantly than treatment with ISL alone. These findings indicate that ISL induced reprogramming in A375 melanoma cells by activating mTORC2-AKT-GSK3β signaling.

Venenum bufonis has been used as an antitumor drug in China for many years. Bufotalin, as an active component of Venenum bufonis, has been proven to exhibit antitumor effects in cancer types. In the present study, the effect of bufotalin on the human melanoma skin cancer cell line A375 was analyzed using MTT and colony formation assays. Bufotalin significantly inhibited the proliferation and colony formation of A375 cells. Further studies demonstrated that bufotalin significantly upregulated the protein levels of ATM serine/threonine kinase and Chk2, downregulated CDC25C protein expression, and subsequently inhibited CDK1 expression, leading to cell cycle arrest at the G2/M phase of the A375 cells. Furthermore, bufotalin significantly increased BAX expression levels, decreased BCL-2 expression, and then upregulated apoptosis-related proteins, caspase-3/-9, followed by A375 cell apoptosis. Taken together, these results show that bufotalin induces cell cycle arrest at the G2/M phase and cell apoptosis, resulting in the inhibition of A375 cell proliferation, thereby suggesting that bufotalin may be utilized in melanoma treatment.

Melanoma is the most malignant type of skin cancer and is resistant to numerous chemotherapeutic and radiotherapy-based treatment approaches due to the activation of rapid and reversible pro-survival signaling pathways. As a result, patients will often present with a poor prognosis. Therefore, novel preventive methods and treatments are urgently required for patients with melanoma. Vitamin C (also known as L-ascorbic acid) is a water-soluble vitamin that is widely used as a dietary additive and has been demonstrated to exhibit anti-cancer properties. In the present study, the effects of vitamin C in human melanoma A375 cells, and the mechanisms underlying these effects were investigated. Vitamin C potently suppressed human melanoma A375 cell proliferation by inducing apoptosis in A375 cells. Induction of apoptosis was related to caspase-9 and caspase-3 activation and the mitochondrial membrane potential of A375 cells significantly decreased in the presence of vitamin C. Furthermore, vitamin C induced apoptosis in A375 cells by activating the Bax-and Bcl-2-mediated mitochondrial pathway. These results indicate that vitamin C may be a potentially useful clinical anti-tumor drug for treating patients with melanoma.Abbreviations: Bcl-2, BCL2 apoptosis regulator; Bax, BCL2 associated X; ROS, reactive oxygen species; JC-1, 5,5', 6,6'-tetrachloro-1,1',3,3'-tetraethyl enzamidazolocarbocyanin iodide

The mitochondrial protein mitoNEET is a type of iron-sulfur protein localized to the outer membrane of mitochondria and is involved in a variety of human pathologies including cystic fibrosis, diabetes, muscle atrophy, and neurodegeneration. In the current study, we found that isoliquiritigenin (ISL), one of the components of the root of Glycyrrhiza glabra L., could decrease the expression of mitoNEET in A375 melanoma cells. We also demonstrated that mitoNEET could regulate the content of reactive oxygen species (ROS), by showing that the ISL-mediated increase in the cellular ROS content could be mitigated by the mitoNEET overexpression. We also confirmed the important role of ROS in ISL-treated A375 cells. The increased apoptosis rate and the decreased mitochondrial membrane potential were mitigated by the overexpression of mitoNEET in A375 cells. These findings indicated that ISL could decrease the expression of mitoNEET, which regulated ROS content and subsequently induced mitochondrial dysfunction and apoptosis in A375 cells. Our findings also highlight mitoNEET as a promising mitochondrial target for cancer therapy.

Background: A recent patent has been issued for hydroxysafflor yellow A (HSYA) as a drug to prevent blood circulation disorders. Hydroxysafflor yellow B (HSYB), an isomer of HSYA with antioxidative effects, has been isolated from the florets of Carthamus tinctorius. The effects of HSYB on the proliferation of cancer cells and its mechanism of action have not been investigated. Objective: The aims of this study were to investigate the anti-cancer effects and the molecular mechanism of HSYB for breast cancer MCF-7 cells. Methods: MTT assays and colony formation assays were used to assess the survival and proliferation of MCF-7 cells, respectively. Hoechst 33258 and flow cytometry were used to measure cell apoptosis and flow cytometry to determine effects on the cell cycle. Western blots were used to measure protein levels. Results: Treatment with HSYB reduced survival and proliferation of human breast cancer MCF-7 cells in a dose-dependent manner. Furthermore, HSYB arrested the MCF-7 cell cycle at the S phase and downregulated cyclin D1, cyclin E, and CDK2. Compared with a control group, HSYB suppressed the protein levels of p-PI3K, PI3K, AKT, and p-AKT in MCF-7 cells. In addition, HSYB decreased the levels of Bcl- 2, increased the levels of Bax, cleaved caspase-3 and caspase-9, and subsequently induced MCF-7 cell apoptosis. Conclusion: These data demonstrate that HSYB arrests the MCF-7 cell cycle at the S phase and induces cell apoptosis. Patent US20170246228 indicates that HSYB can be potentially used for the prevention and treatment of human breast cancer.

Doxorubicin (DOX) is currently the preferred chemotherapeutic agent for breast cancer, and hydroxyl safflower yellow B (HSYB) has a tumor growth-inhibiting activity. The present study aimed to investigate the effects of HSYB combined with DOX on the proliferation of human breast cancer MCF-7 cells and explore the underlying mechanism. MTT and cell colony formation assays revealed that the proliferation rate of MCF-7 cells was signifiscantly decreased after HSYB and DOX treatment. Combined HSYB and DOX treatment significantly decreased the expression levels of BCL-2 in MCF-7 cells, while the expression levels of apoptosis-associated proteins, including cleaved caspase-9, BAX and cleaved caspase-3, were markedly increased. Furthermore, flow cytometry and western blot analysis demonstrated that combined HSYB and DOX treatment stimulated an increase in intracellular reactive oxygen species and promoted the release of cytochrome c, leading to apoptosis. The current data suggested that the combination of HSYB and DOX may have marked antitumor activity.

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