Inhibition of Cell Proliferation in an NRAS Mutant Melanoma Cell Line by Combining Sorafenib and α-Mangostin

Autophagy as a targeted therapeutic approach for skin cancer: Evaluating natural and synthetic molecular interventions

Skin cancer, a prevalent malignancy worldwide, poses significant health concerns owing to its increasing incidence. Autophagy, a natural cellular process, is a pivotal event in skin cancer and has advantageous and detrimental effects. This duality has prompted extensive investigations into medical interventions targeting autophagy modulation for their substantial therapeutic potential. This systematic review aimed to investigate the relationship between skin cancer and autophagy and the contribution and mechanism of autophagy modulators in skin cancer. We outlined the effectiveness and safety of targeting autophagy as a promising therapeutic strategy for the treatment of skin cancer. This comprehensive review identified a diverse array of autophagy modulators with promising potential for the treatment of skin cancer. Each of these compounds demonstrates efficacy through distinct physiological mechanisms that have been elucidated in detail. Interestingly, findings from a literature search indicated that none of the natural, synthetic, or semisynthetic compounds exhibited notable adverse effects in either human or animal models. Consequently, this review offers novel mechanistic and therapeutic perspectives on the targeted modulation of autophagy in skin cancer.

In vitro and in silico study on the effect of carvedilol and sorafenib alone and in combination on the growth and inflammatory response of melanoma cells

Melanoma is an aggressive skin cancer. Increasing evidence has shown the role of β-adrenergic receptors in the pathogenesis of melanoma. Carvedilol is a widely used non-selective β-AR antagonist with potential anticancer activity. The purpose of the study was to estimate the influence of carvedilol and sorafenib alone and in combination on the growth and inflammatory response of C32 and A2058 melanoma cells. Furthermore, this study also aimed to predict the probable interaction of carvedilol and sorafenib when administered together. Predictive study of the interaction of carvedilol and sorafenib was performed using the ChemDIS-Mixture system. Carvedilol and sorafenib alone and in combination showed a growth inhibitory effect on cells. The greatest synergistic antiproliferative effect on both cell lines was observed at Car 5 μM combined with Sor 5 μM. Analysis in silico identified diseases, proteins, and metabolic pathways that can be affected by the interaction of carvedilol and sorafenib. The results obtained demonstrated that carvedilol and sorafenib modulated the secretion of IL-8 by IL-1β-stimulated by melanoma cell lines but the use of a combination of both drugs did not intensify the effect. In summary, the results presented indicate that the combination of carvedilol and sorafenib may have a promising anticancer effect on melanoma cells.

The purple mangosteen (Garcinia mangostana): Defining the anticancer potential of selected xanthones

The purple mangosteen (Garcinia mangostana) is a popular Southeast Asian fruit that has been used traditionally for its health promoting benefits for years. Unique to the mangosteen are a class of phytochemicals known as xanthones that have been reported to display significant anti-cancer and anti-tumor activities, specifically through the promotion of apoptosis, targeting of specific cancer-related proteins, or modulation of cell signaling pathways. α-Mangostin, the most abundant xanthone isolated from the mangosteen, has received substantial attention as it has proven to be a potent phytochemical, specifically as an anticancer agent, in numerous different cancer cell studies and cancer animal models. While the mechanisms for these anticancer effects have been reported in many studies, lesser xanthones, including gartanin, β-mangostin, γ-mangostin, garcinone C, and garcinone E, and mangosteen extracts from the pericarp, roots, rind, and stem show promise for their anticancer activity but their mechanisms of action are not as well developed and remain to be determined. Mangosteen products appear safe and have been well tolerated in human clinical trials where they show antioxidant activity, though their clinical anticancer activity has not yet been evaluated. This review summarizes the work that has been done to explore and explain the anticancer and antitumor activities of α-mangostin, lesser xanthones, and mangosteen extracts in vitro, in vivo, and in humans in various cancers.

α-Mangostin Synergizes the Antineoplastic Effects of 5-Fluorouracil Allowing a Significant Dose Reduction in Breast Cancer Cells

Breast cancer is the most common neoplasm and the leading cause of cancer death in women worldwide. Although 5-fluorouracil is a conventional chemotherapeutic agent for breast cancer treatment, its use may result in severe side effects. Thus, there is widespread interest in lowering 5-fluorouracil drawbacks, without affecting its therapeutic efficacy by the concomitant use with natural products. Herein, we aimed at evaluating whether α-mangostin, a natural antineoplastic compound, could increase the anticancer effect of 5-fluorouracil in different breast cancer cell lines, allowing for dose reduction. Cell proliferation was evaluated by sulforhodamine-B assays, inhibitory concentrations and potency were calculated by dose-response curves, followed by analysis of their pharmacological interaction by the combination-index method and dose-reduction index. Cell cycle distribution was evaluated by flow cytometry. Each compound inhibited cell proliferation in a dose-dependent manner, the triple negative breast cancer cells being the most sensitive. When 5-fluorouracil and α-mangostin were used concomitantly, synergistic antiproliferative effect was observed. The calculated dose-reduction index suggested that this combination exhibits therapeutic potential for reducing 5-fluorouracil dosage in breast cancer. Mechanistically, the cotreatment induced cell death in a greater extent than each drug alone. Therefore, α-mangostin could be used as a potent co-adjuvant for 5-fluorouracil in breast cancer.

Natural Products Targeting the Mitochondria in Cancers

There are abundant sources of anticancer drugs in nature that have a broad prospect in anticancer drug discovery. Natural compounds, with biological activities extracted from plants and marine and microbial metabolites, have significant antitumor effects, but their mechanisms are various. In addition to providing energy to cells, mitochondria are involved in processes, such as cell differentiation, cell signaling, and cell apoptosis, and they have the ability to regulate cell growth and cell cycle. Summing up recent data on how natural products regulate mitochondria is valuable for the development of anticancer drugs. This review focuses on natural products that have shown antitumor effects via regulating mitochondria. The search was done in PubMed, Web of Science, and Google Scholar databases, over a 5-year period, between 2015 and 2020, with a keyword search that focused on natural products, natural compounds, phytomedicine, Chinese medicine, antitumor, and mitochondria. Many natural products have been studied to have antitumor effects on different cells and can be further processed into useful drugs to treat cancer. In the process of searching for valuable new drugs, natural products such as terpenoids, flavonoids, saponins, alkaloids, coumarins, and quinones cover the broad space.

The Effect of Alpha Mangostin on Epithelial-Mesenchymal Transition on Human Hepatocellular Carcinoma HepG2 Cells Surviving Sorafenib via TGF-β/Smad Pathways

Purpose: This study was intended to find out the impact of alpha mangostin administration on the epithelial-mesenchymal transition (EMT) markers and TGF-β/Smad pathways in hepatocellular carcinoma Hep-G2 cells surviving sorafenib.

Methods: Hepatocellular carcinoma HepG2 cells were treated with sorafenib 10 μM. Cells surviving sorafenib treatment (HepG2^surv) were then treated vehicle, sorafenib, alpha mangostin, or combination of sorafenib and alpha mangostin. Afterward, cells were observed for their morphology with an inverted microscope and counted for cell viability. The concentrations of transforming growth factor (TGF)-β1 in a culture medium were examined using ELISA. The mRNA expressions of TGF-β1, TGF-β1-receptor, Smad3, Smad7, E-cadherin, and vimentin were evaluated using quantitative reverse transcriptase–polymerase chain reaction. The protein level of E-cadherin was also determined using western blot analysis.

Results: Treatment of alpha mangostin and sorafenib caused a significant decrease in the viability of sorafenib-surviving HepG2 cells versus control (both groups with P <0.05). Our study found that alpha mangostin treatment increased the expressions of vimentin (P <0.001 versus control). In contrast, alpha mangostin treatment tends to decrease the expressions of Smad7 and E-cadherin (both with P >0.05). In line with our findings, the expressions of TGF-β1 and Smad3 are significantly upregulated after alpha mangostin administration (both with P <0.05) versus control.

Conclusion: Alpha mangostin reduced cell viability of sorafenib-surviving HepG2 cells; however, it also enhanced epithelial–mesenchymal transition markers by activating TGF-β/Smad pathways.

Antitumor and anti-nematode activities of α-mangostin

α-Mangostin, one of the major xanthones isolated from pericarp of mangosteen (Garcinia mangostana Linn), exhibits a wide range of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial as well as anticancer, both in in vitro and in vivo studies. In the present study, α-mangostin' anti-cancer and anti-parasitic properties were tested in vitro against three human cell lines, including squamous carcinoma (SCC-15) and glioblastoma multiforme (U-118 MG), compared to normal skin fibroblasts (BJ), and in vivo against Caenorhabditis elegans. The drug showed cytotoxic activity, manifested by decrease of cell viability, inhibition of proliferation, induction of apoptosis and reduction of adhesion at concentrations lower than 10 μM (the IC₅₀ values were 6.43, 9.59 and 8.97 μM for SCC-15, U-118 MG and BJ, respectively). The toxicity, causing cell membrane disruption and mitochondria impairment, was selective against squamous carcinoma with regard to normal cells. Moreover, for the first time anti-nematode activity of α-mangostin toward C. elegans was described (the LC₅₀ = 3.8 ± 0.5 μM), with similar effect exerted by mebendazole, a well-known anthelmintic drug.

Design, synthesis and structure–activity relationships of mangostin analogs as cytotoxic agents

A series xanthone derivatives were synthesized and cytotoxicity results indicated that the isopentene group at C-8 is essential.

Treatment of NRAS-mutated advanced or metastatic melanoma: rationale, current trials and evidence to date

The disease course of BRAF (v-raf murine sarcoma viral oncogene homolog B1)-mutant melanoma has been drastically improved by the arrival of targeted therapies. NRAS (neuroblastoma RAS viral oncogene homolog)-mutated melanoma represents 15–25% of all metastatic melanoma patients. It currently does not have an approved targeted therapy. Metastatic patients receive immune-based therapies as first-line treatments, then cytotoxic chemotherapy like carboplatin/paclitaxel (C/P), dacarbazine (DTIC) or temozolomide (TMZ) as a second-line treatment. We will review current preclinical and clinical developments in NRAS-mutated melanoma, and analyze ongoing clinical trials that are evaluating the benefit of different targeted and immune-based therapies, either tested as single agents or in combination, in NRAS-mutant melanoma.

The naturally occurring xanthone α-mangostin induces ROS-mediated cytotoxicity in non-small scale lung cancer cells

Small cell lung cancer (NSCLC) accounts for 85% of total deaths globally, and recent studies indicate the increasing risks of NSCLC in China and South Asian countries. Hence, development of new therapeutics against NSCLC has been a major concern. α-Mangostin, a naturally occurring xanthone, found abundantly in pericarps of mangosteen fruit is well known for its medicinal importance. The anticancer properties of α-mangostin against several types of cancer are also well documented. But the mechanism of action of α-mangostin against lung cancer is not well understood and requires further investigation. Therefore in the present study, we explored the therapeutic potential of α-mangostin against A549 cells. Treatment of A549 cells with α-mangostin resulted in a dose-dependent loss of cell viability, while the non-malignant cells such as hPBMC and WI-38 remained unaffected. Further we observed that the ROS plays an important role in α-mangostin -induced apoptosis in A549 cells, and administration of N-acetyl cysteine significantly abrogates α-mangostin -mediated cytotoxicity in lung cancer cells. Overall, α-mangostin induces ROS-mediated cytotoxicity in NSCLC cells.

Autophagy: In the cROSshairs of cancer

Two prominent features of tumors that contribute to oncogenic survival signaling are redox disruption, or oxidative stress phenotype, and high autophagy signaling, making both phenomena ideal therapeutic targets. However, the relationship between redox disruption and autophagy signaling is not well characterized and the clinical impact of reactive oxygen species (ROS)-generating chemotherapeutics on autophagy merits immediate attention as autophagy largely contributes to chemotherapeutic resistance. In this commentary we focus on melanoma, using it as an example to provide clarity to current literature regarding the roles of autophagy and redox signaling which can be applicable to initiation and maintenance of most tumor types. Further, we address the crosstalk between ROS and autophagy signaling during pharmacological intervention and cell fate decisions. We attempt to elucidate the role of autophagy in regulating cell fate following treatment with ROS-generating agents in preclinical and clinical settings and discuss the emerging role of autophagy in cell fate decisions and as a cell death mechanism. We also address technical aspects of redox and autophagy evaluation in experimental design and data interpretation. Lastly, we present a provocative view of the clinical relevance, emerging challenges in dual targeting of redox and autophagy pathways for therapy, and the future directions to be addressed in order to advance both basic and translational aspects of this field.