Resveratrol Enhances Chemosensitivity in Mouse Melanoma Model Through Connexin 43 Upregulation

Exposure to phenols reduces melanogenesis in B16F10 cells and zebrafish

Phenols, ubiquitous environmental contaminants found in water, soil, and air, pose risks to organisms even at minimal concentrations, and many are classified as hazardous pollutants. Skin pigmentation is a natural shield against ultraviolet-induced DNA damage and oxidative stress, pivotal in reducing skin cancer incidences. Studies on B16F10 melanoma cells and zebrafish offer valuable insights into potential therapeutic avenues for melanoma in the context of phenol exposure. Upon phenol treatment, there was a marked decrease in melanin content and melanogenesis-associated protein expression, such as tyrosinase and the microphthalmia-associated transcription factor (MITF) in these melanoma cells. Additionally, phenols led to diminished p38 phosphorylation, amplified extracellular signal-regulated kinase (ERK) phosphorylation, and curtailed melanin expression in zebrafish. These observations underscore the detrimental impact of phenols on melanogenesis and propose a mechanism of action centered on the ERK/p38 signaling pathway. Consequently, our data spotlight the adverse effects of phenols on melanogenesis."

NEDD4L inhibits migration, invasion, cisplatin resistance and promotes apoptosis of bladder cancer cells by inactivating the p62/Keap1/Nrf2 pathway

PURPOSE

This study identified the function of neural precursor cell expressed developmentally down-regulated 4-like (NEDD4L) on bladder cancer (BLCA).

METHODS

NEDD4L expression in BLCA patients was scrutinized. The function of NEDD4L on the viability, apoptosis, migration and invasion of BLCA cells was evaluated by cell counting kit-8, flow cytometry and Transwell assays. The effect of NEDD4L on the cisplatin (DDP) resistance of the DDP-resistant BLCA cells was explored. The influence of NEDD4L on the p62/Keap1/Nrf2 pathway activity in BLCA cells was tested by Western blot. Rescue experiments were implemented to verify whether NEDD4L regulated BLCA cell malignant behavior by mediating the Keap1/Nrf2 pathway activity via p62. The effect of NEDD4L on the growth and the p62/Keap1/Nrf2 pathway activity in vivo was researched in xenograft tumor nude mice models.

RESULTS

The down-regulated NEDD4L in BLCA patients was associated with unfavorable survival. NEDD4L suppressed the viability (inhibition rate 57.1%/49.0%), migration (inhibition rate 49.7%/77.1%), invasion (inhibition rate 50.6%/75.7%), promoted the apoptosis of T24/5637 cells (promotion rate 243.8%/201.9%), reduced IC 50 of DDP-resistant T24/5637 cells from 132.2/101.8 to 57.81/59.71 μM, respectively, and inactivated the p62/Keap1/Nrf2 pathway in T24/5637 cells. p62 up-regulation partially abrogated the inhibition of NEDD4L on the Keap1/Nrf2 pathway activity, the malignant behavior of BLCA cells, and the DDP resistance of DDP-resistant BLCA cells. NEDD4L overexpression inhibited the tumor growth and the p62/Keap1/Nrf2 pathway activity in vivo in BLCA.

CONCLUSION

NEDD4L inhibits the progression of BLCA by inactivating the p62/Keap1/Nrf2 pathway. It may be an effective target for BLCA treatment.

Exceptional Properties of Lepidium sativum L. Extract and Its Impact on Cell Viability, Ros Production, Steroidogenesis, and Intracellular Communication in Mice Leydig Cells In Vitro

The prevalence of reproductive dysfunction in males has risen in the last few years, and alternative therapies are gradually gaining in popularity. Our in vitro study aimed to evaluate the potential impact of Lepidium sativum L. on mice TM3 Leydig cells, concerning basal parameters such as cell viability, cell membrane integrity, and lysosomal activity, after 24 h and 48 h exposure. Moreover, reactive oxygens species generation, sex-steroid hormone secretion, and intercellular communication were quantified. In the present study, the microgreen extract from Lepidium was rich in ferulic acid, 4-OH benzoic acid, and resveratrol, with a significant antioxidant activity. The results showed that lower experimental doses (62.5–250 µg/mL) could positively affect the observed parameters, with significant differences at 250 µg/mL after 24 h and 48 h, respectively. Potential risks could be associated with higher concentrations, starting at 500 µg/mL, 1000 µg/mL, and 2000 µg/mL of Lepidium. Nevertheless, biochemical quantification indicated a significant antioxidant potential and a rich content of biologically active molecules at the applied doses, and time determined the intracellular response of the cultured model.

Potential Therapeutic Targets of Resveratrol, a Plant Polyphenol, and Its Role in the Therapy of Various Types of Cancer

Cancer is among the most prominent causes of mortality worldwide. Different cancer therapy modes employed, including chemotherapy and radiotherapy, have been reported to be significant in cancer management, but the side effects associated with these treatment strategies are still a health problem. Therefore, alternative anticancer drugs based on medicinal plants or their active compounds have been generating attention because of their less serious side effects. Medicinal plants are an excellent source of phytochemicals that have been recognized to have health-prompting effects through modulating cell signaling pathways. Resveratrol is a well-known polyphenolic molecule with antioxidant, anti-inflammatory, and health-prompting effects among which its anticancer role has been best defined. Additionally, this polyphenol has confirmed its role in cancer management because it activates tumor suppressor genes, suppresses cell proliferation, induces apoptosis, inhibits angiogenesis, and modulates several other cell signaling molecules. The anticancer potential of resveratrol is recognized in numerous in vivo and in vitro studies. Previous experimental data suggested that resveratrol may be valuable in cancer management or improve the efficacy of drugs when given with anticancer drugs. This review emphasizes the potential role of resveratrol as an anticancer drug by modulating numerous cells signaling pathways in different types of cancer.

Connexin channels modulation in pathophysiology and treatment of immune and inflammatory disorders

Connexin-mediated intercellular communication mechanisms include bidirectional cell-to-cell coupling by gap junctions and release/influx of molecules by hemichannels. These intercellular communications have relevant roles in numerous immune system activities. Here, we review the current knowledge about the function of connexin channels, mainly those formed by connexin-43, on immunity and inflammation. Focusing on those evidence that support the design and development of therapeutic tools to modulate connexin expression and/or channel activities with treatment potential for infections, wounds, cancer, and other inflammatory conditions.

Connexins in melanoma: Potential role of Cx46 in its aggressiveness

Melanoma is the most aggressive skin cancer, and in metastatic advanced states, it is completely refractory to chemotherapy. Therefore, it is relevant to understand the molecular bases that rule their aggressiveness. Connexins (Cxs) are proteins that under normal physiological conditions participate in intercellular communication, via the exchange of signaling molecules between the cytoplasm and extracellular milieu and the exchange of ions/second messengers between the cytoplasm of contacting cells. These proteins have shown important roles in cancer progression, chemo- and radiotherapy resistance, and metastasis. Accordingly, Cx26 and Cx43 seem to play important roles in melanoma progression and metastasis. On the other hand, Cx46 is typically expressed in the eye lens, where it seems to be associated with oxidative stress protection in fiber lens cells. However, in the last decade, Cx46 expression has been associated with breast and brain cancers, due to its role in potentiation of both extracellular vesicle release and cancer stem cell-like properties. In this review, we analyzed a potential role of Cx46 as a new biomarker and therapeutic target in melanoma.

Cx43 deficiency confers EMT-mediated tamoxifen resistance to breast cancer via c-Src/PI3K/Akt pathway

Tamoxifen (TAM) resistance has indicated a significant challenge during endocrine therapy for hormone-sensitive breast cancer. Thus, it is significant to elucidate the molecular events endowing TAM resistance to endocrine therapy. In this study, we found that epithelial-mesenchymal transition (EMT) was an important event to confer TAM resistance, and attenuating EMT by elevating connexin (Cx) 43 expression could reverse TAM resistance. Specifically, Cx43 overexpression improved TAM sensitivity, while Cx43 depletion facilitated TAM insensitivity by modulating EMT in T47D TAM-resistant and -sensitive cells, and transplanted xenografts. Importantly, we found a novel reciprocal regulation between Cx43 and c-Src/PI3K/Akt pathway contributing to EMT and TAM resistance in breast cancer. Moreover, we identified that Cx43 deficiency was significantly correlated with poor relapse-free survival in patients undergoing TAM treatment. Therefore, Cx43 represents a prognostic marker and an attractive target for breast cancer treatments. Therapeutic strategies designed to increase or maintain Cx43 function may be beneficial to overcome TAM resistance.

Effects of Alpha-Connexin Carboxyl-Terminal Peptide (aCT1) and Bowman-Birk Protease Inhibitor (BBI) on Canine Oral Mucosal Melanoma (OMM) Cells

Oral mucosal melanomas (OMM) are aggressive cancers in dogs, and are good models for human OMM. Gap junctions are composed of connexin units, which may have altered expression patterns and/or subcellular localization in cancer cells. Cell-to-cell communication by gap junctions is often impaired in cancer cells, including in melanomas. Meanwhile, the upregulated expression of the gap junction protein connexin 43 (Cx43) inhibits melanoma progression. The α-connexin carboxyl-terminal (aCT1) peptide reportedly maintains Cx43 expression and cell-cell communication in human mammary cells and increases the communication activity through gap junctions in functional assays, therefore causing decreased cell proliferation. The Bowman-Birk protease inhibitor (BBI), a component of soybeans, induces Cx43 expression in several tumor cells as a trypsin–chymotrypsin inhibition function, with antineoplastic effects. This study investigated the effect of aCT1 peptide and BBI treatment, alone or in combination, on TLM1 canine melanoma cell viability. Cell viability after treatment with aCT1, the reverse sequence peptide (R-pep), and/or BBI for 5 days was analyzed by PrestoBlue assay. Immunofluorescence was used to observe Cx43 localization and expression. aCT1 (200 μM) alone did not significantly decrease cell viability in TLM1 cells, whereas BBI (400 μg/ml) alone significantly decreased the TLM1 viability. Combined treatment with both aCT1 (200 μM) and BBI (400 μg/ml) significantly decreased cell viability in TLM1 cells. Cx43 expression, as identified by immunostainings in TLM1 cells, was increased in the cell membrane after the combination treatment with BBI and aCT1. This dual treatment can be combined to achieve the anticancer activity, possibly by increasing Cx 43 expression and affecting Cx43 migration to the cell membrane. In conclusion, a treatment strategy targeting Cx43 with BBI and aCT1 may possibly lead to new effective therapies for canine OMM.

Resveratrol as Chemosensitizer Agent: State of Art and Future Perspectives

Resistance to chemotherapy still remains a major challenge in the clinic, impairing the quality of life and survival rate of patients. The identification of unconventional chemosensitizing agents is therefore an interesting aspect of cancer research. Resveratrol has emerged in the last decades as a fascinating molecule, able to modulate several cancer-related molecular mechanisms, suggesting a possible application as an adjuvant in cancer management. This review goes deep into the existing literature concerning the possible chemosensitizing effect of resveratrol associated with the most conventional chemotherapeutic drugs. Despite the promising effects observed in different cancer types in in vitro studies, the clinical translation still presents strong limitations due to the low bioavailability of resveratrol. Recently, efforts have been moved in the field of drug delivery to identifying possible strategies/formulations useful for a more effective administration. Despite the necessity of a huge implementation in this research area, resveratrol appears as a promising molecule able to sensitize resistant tumors to drugs, suggesting its potential use in therapy-refractory cancer patients.

Resveratrol's Anti-Cancer Effects through the Modulation of Tumor Glucose Metabolism

Simple Summary

The prevention and treatment of cancer is an ongoing medical challenge. In the context of personalized medicine, the well-studied polyphenol resveratrol could complement classical tumor therapy. It may affect key processes such as inflammation, angiogenesis, proliferation, metastasis, glucose metabolism, and apoptosis in various cancers because resveratrol acts as a multi-targeting agent by modulating multiple signal transduction pathways. This review article focuses on resveratrol’s ability to modify tumor glucose metabolism and its associated therapeutic capacity. Resveratrol reduces glucose uptake and glycolysis by affecting Glut1, PFK1, HIF-1α, ROS, PDH, and the CamKKB/AMPK pathway. It also inhibits cell growth, invasion, and proliferation by targeting NF-kB, Sirt1, Sirt3, LDH, PI-3K, mTOR, PKM2, R5P, G6PD, TKT, talin, and PGAM. In addition, resveratrol induces apoptosis by targeting integrin, p53, LDH, and FAK. In conclusion, resveratrol has many potentials to intervene in tumor processes if bioavailability can be increased and this natural compound can be used selectively.

Abstract

Tumor cells develop several metabolic reprogramming strategies, such as increased glucose uptake and utilization via aerobic glycolysis and fermentation of glucose to lactate; these lead to a low pH environment in which the cancer cells thrive and evade apoptosis. These characteristics of tumor cells are known as the Warburg effect. Adaptive metabolic alterations in cancer cells can be attributed to mutations in key metabolic enzymes and transcription factors. The features of the Warburg phenotype may serve as promising markers for the early detection and treatment of tumors. Besides, the glycolytic process of tumors is reversible and could represent a therapeutic target. So-called mono-target therapies are often unsafe and ineffective, and have a high prevalence of recurrence. Their success is hindered by the ability of tumor cells to simultaneously develop multiple chemoresistance pathways. Therefore, agents that modify several cellular targets, such as energy restriction to target tumor cells specifically, have therapeutic potential. Resveratrol, a natural active polyphenol found in grapes and red wine and used in many traditional medicines, is known for its ability to target multiple components of signaling pathways in tumors, leading to the suppression of cell proliferation, activation of apoptosis, and regression in tumor growth. Here, we describe current knowledge on the various mechanisms by which resveratrol modulates glucose metabolism, its potential as an imitator of caloric restriction, and its therapeutic capacity in tumors.

Salmonella alters heparanase expression and reduces tumor metastasis

Salmonella causes salmonellosis, is a facultative anaerobe and is one of the common Gram-negative bacteria. Salmonella has anti-tumor potential and tumor-targeting activity. The heparin sulfate on cell surfaces can be cleaved by heparanase that is an endo-β-D-glucuronidase. Heparanase can destroy the extracellular matrix and is involved in tumor metastasis and angiogenic activity. Previously, Salmonella was demonstrated to inhibit tumor metastasis. It remains unclear whether Salmonella inhibits metastasis by regulating heparanase. The expression of heparanase in Salmonella-treated tumor cells was found to be decreased. Transwell and wound-healing assays demonstrated the inhibition of cell migration after Salmonella treatment. Salmonella was found to influence the levels of phosphate-protein kinase B (P-AKT) and phosphate-extracellular regulated protein kinases (P-ERK), which are involved in heparanase expression. Salmonella reduced the heparanase expression induced upregulating PERK and PAKT signaling pathways. The mice bearing an experimental metastasis tumor model was used to evaluate the anti-tumor metastatic effects of Salmonella. Compared with the control group, Salmonella significantly reduced the number of metastatic nodules and enhanced survival. The results of our study indicate that Salmonella plays a vital role in the inhibition of tumor metastasis through the downregulation of heparanase.

Emerging functions and clinical prospects of connexins and pannexins in melanoma

Cellular communication through gap junctions and hemichannels formed by connexins and through channels made by pannexins allows for metabolic cooperation and control of cellular activity and signalling. These channel proteins have been described to be tumour suppressors that regulate features such as cell death, proliferation and differentiation. However, they display cancer type-dependent and stage-dependent functions and may facilitate tumour progression through junctional and non-junctional pathways. The accumulated knowledge and emerging strategies to target connexins and pannexins are providing novel clinical opportunities for the treatment of cancer. Here, we provide an updated overview of the role of connexins and pannexins in malignant melanoma. We discuss how targeting of these channel proteins may be used to potentiate antitumour effects in therapeutic settings, including through improved immune-mediated tumour elimination.

Resveratrol Sensitizes Colorectal Cancer Cells to Cetuximab by Connexin 43 Upregulation-Induced Akt Inhibition

Cetuximab is a monoclonal antibody that acts as an anti-epidermal growth factor receptor (EGFR) agent. Cetuximab inhibits the phosphorylation and activation of EGFR and blocks downstream signal pathways of EGF/EGFR, including Ras-Raf-MAPK and PI3K-Akt pathways. Akt activation is an important factor in cetuximab resistance. It has been reported that resveratrol and connexin 43 regulate Akt in different ways based on tissue type. Since connexin 43 interacts with Akt, and resveratrol is known to upregulate connexin 43, we investigated whether resveratrol can sensitize colorectal cancer cells to cetuximab via connexin 43 upregulation. Our work confirmed that resveratrol increases the inhibition of growth by cetuximab in vitro and in vivo, upregulates connexin 43 expression and phosphorylation, increases gap junction function, and inhibits the activation of Akt and NFκB in parental or cetuximab-treated parental HCT116 and CT26 cells. Resveratrol did not exhibit these effects on connexin 43-shRNA transfected cells, so connexin 43 upregulation may contribute to Akt inhibition in these cells. Given these data, resveratrol may sensitize colorectal cancer cells to cetuximab via upregulating connexin 43 to inhibit the Akt pathway.

Unraveling the molecular mechanisms and the potential chemopreventive/therapeutic properties of natural compounds in melanoma

Melanoma is the most fatal form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, targeted therapy and immunotherapy. However, these treatment strategies are associated with development of drug resistance and severe side effects. In recent years, natural compounds have also been extensively studied for their anti-melanoma effects, including tumor growth inhibition, apoptosis induction, angiogenesis and metastasis suppression and cancer stem cell elimination. Moreover, a considerable number of studies reported the synergistic activity of phytochemicals and standard anti-melanoma agents, as well as the enhanced effectiveness of their synthetic derivatives and novel formulations. However, clinical data confirming these promising effects in patients are still scanty. This review emphasizes the anti-tumor mechanisms and potential application of the most studied natural products for melanoma prevention and treatment.

Eicosapentaenoic acids enhance chemosensitivity through connexin 43 upregulation in murine melanoma models

Chemotherapy is now in common use for the treatment of tumors; however, with tumor growth retardation comes the severe side effects that occur after a chemotherapy cycle. Eicosapentaenoic acids (EPA) used in combination with chemotherapy has an additive effects and provides a rationale for using EPA in tandem with chemotherapy. To improve the efficacy and safety of this combination therapy, a further understanding that EPA modulates with the tumor microenvironment is necessary. Connexin 43 (Cx43) is involved in enhancing chemosensitivity that was suppressed in a tumor microenvironment. We aim to investigate the role of EPA in chemosensitivity in murine melanoma by inducing Cx43 expression. The dose-dependent upregulation of Cx43 expression and gap junction intercellular communication were observed in B16F10 cells after EPA treatment. Furthermore, EPA significantly increased the expression levels of mitogen-activated protein kinases (MAPK) signaling pathways. The EPA-induced Cx43 expression was reduced after MAPK inhibitors. Knockdown Cx43 in B16F10 cells reduced the therapeutic effects of combination therapy (EPA plus 5-Fluorouracil). Our results demonstrate that the treatment of EPA is a tumor induced Cx43 gap junction communication and enhances the combination of EPA and chemotherapeutic effects.

The extracts of Astragalus membranaceus enhance chemosensitivity and reduce tumor indoleamine 2, 3-dioxygenase expression

Astragalus membranaceus has been shown to possess anti-inflammation and antitumor properties. Several studies have indicated that extracts of Astragalus membranaceus (PG2) have growth inhibitory effects on tumor. However, the effect of PG2 on enhancing the chemotherapy, modulating tumor immune escape and their mechanism of action is unknown and need further investigation. Connexin (Cx) 43 is ubiquitous in cells and involved in facilitating the passage of chemotherapeutic drugs to bystander tumor cells. The indoleamine 2, 3-dioxygenase (IDO) depletes tryptophan, reduces the active T cell number and destroys immune surveillance. Herein, we provide evidence that the treatment of PG2 induced Cx43 expression, decreases IDO expression and enhances the distribution of chemotherapeutic drug. However, the effects of combination therapy (PG2 plus cisplatin) in animal models significantly retarded tumor growth and prolonged the survival. We believe that the information provided in this study may aid in the design of future therapy of PG2, suggest suitable combinations with chemotherapies.

Resveratrol alleviates oxidative damage in enteric neurons and associated gastrointestinal dysfunction caused by chemotherapeutic agent oxaliplatin

Oxaliplatin is a first-line chemotherapeutic agent used for the treatment of colorectal cancer. Its use is associated with severe gastrointestinal (GI) side-effects, associated with oxidative damage and neurotoxicity to the enteric neurons. Resveratrol is a potent anti-oxidant that has been shown to protect against oxidative damage and neurotoxicity in other neurons and could therefore prevent oxaliplatin-induced damage to enteric neurons. We determined whether co-administration of resveratrol with oxaliplatin alleviates enteric neuron toxicity and GI dysfunction in mice. Colons were collected for immunohistochemical analysis of myenteric neurons and assessment of motor activity in organ-bath experiments. Morphological damage to the colonic mucosa and muscles was analysed. Oxaliplatin treatment induced translocation of nitrated proteins into the nuclei of myenteric neurons and significant damage to the mucosal lining, vacuolisation and a decrease in muscle thickness. This damage is linked to motor dysfunction due to inhibition of the amplitude of colonic contractions, leading to chronic constipation. Co-treatment with resveratrol prevented oxaliplatin-induced neurotoxicity, alleviated damage to GI mucosa, crypts and muscle layer, resulting in improved contractility and a decrease in constipation. Resveratrol could be integrated as part of a therapeutic regimen to help alleviate oxaliplatin-induced GI dysfunction.

The inhibition of indoleamine 2, 3-dioxygenase 1 by connexin 43

Upregulation of connexin 43 (Cx43) showed potential in enhancing immune surveillance that was suppressed in the tumor microenvironment. The expression of indoleamine 2, 3-dioxygenase (IDO) is one of the crucial factors contributing to tumor immune tolerance by depletion of tryptophan and IDO-mediated tryptophan metabolites. Here, we aim to investigate the role of Cx43 in IDO production in murine tumor by using Cx43 inducers. Resveratrol (trans-3, 5, 4 '-trihydroxystilbene) is a natural plant-derived polyphenol possessing positive effect against cancer. Salmonella enterica serovar choleraesuis (S.C.) was proved to target and inhibit tumor growth. Both of them regulated Cx43 expression in tumor cells and led to either chemosensitizing or immune-activating. In this study, the correlation between Cx43 and IDO were determined by the treatment of resveratrol and S.C. Our data showed an increase in Cx43 while IDO protein and IDO-mediated inhibited effects on T cell decreased after tumor cells are given with resveratrol and S.C.

TREATMENTS

All of which could be inhibited once the expression of Cx43 was blocked. Cx43 involved in IDO regulation might be useful in developing IDO-targeted cancer immune therapy.

Cisplatin and resveratrol induce apoptosis and autophagy following oxidative stress in malignant mesothelioma cells

Malignant mesothelioma (MM) is characterized by poor responsiveness to current chemotherapeutic drugs, usually owing to high resistance to apoptosis. Here, we investigated chemosensitizing effects of phytochemical resveratrol, in combination with cisplatin, on MM cells. The combination treatment of cisplatin and resveratrol (CDDP/RSV) synergistically induced apoptosis, as evidenced by typical cell morphological changes, the appearance of sub-G0/G1 peak, an increase in the Annexin V(+) cells and the cleavage of caspase-3 and PARP. CDDP/RSV increased ROS production and depolarization of mitochondrial membrane potential with an increase in the Bax/Bcl-2 ratio. These changes were attenuated by pretreatment with N-acetylcysteine, suggesting that CDDP/RSV induced apoptosis through oxidative mitochondrial damage. Compared with MSTO-211H cells, CDDP/RSV was less efficient in killing H-2452 cells. H-2452 cells exhibited an enhanced autophagy to CDDP/RSV, as observed by an increase in viable cells exhibiting intense LysoTracker Red staining and up-regulation of Beclin-1 and LC3A. Inhibition of autophagy by bafilomycin A1 rendered cells more sensitive to CDDP/RSV-induced cytotoxicity and this was associated with induction of apoptosis. These data indicate that the increased resistance of H-2452 cells to CDDP/RSV is closely related to the activation of self-defensive autophagy, and provide the rationale for targeting the autophagy regulation in the treatment of MM.

Targeting drivers of melanoma with synthetic small molecules and phytochemicals

Melanoma is the least common form of skin cancer, but it is responsible for the majority of skin cancer deaths. Traditional therapeutics and immunomodulatory agents have not shown much efficacy against metastatic melanoma. Agents that target the RAS/RAF/MEK/ERK (MAPK) signaling pathway - the BRAF inhibitors vemurafenib and dabrafenib, and the MEK1/2 inhibitor trametinib - have increased survival in patients with metastatic melanoma. Further, the combination of dabrafenib and trametinib has been shown to be superior to single agent therapy for the treatment of metastatic melanoma. However, resistance to these agents develops rapidly. Studies of additional agents and combinations targeting the MAPK, PI3K/AKT/mTOR (PI3K), c-kit, and other signaling pathways are currently underway. Furthermore, studies of phytochemicals have yielded promising results against proliferation, survival, invasion, and metastasis by targeting signaling pathways with established roles in melanomagenesis. The relatively low toxicities of phytochemicals make their adjuvant use an attractive treatment option. The need for improved efficacy of current melanoma treatments calls for further investigation of each of these strategies. In this review, we will discuss synthetic small molecule inhibitors, combined therapies and current progress in the development of phytochemical therapies.

Connexin 43 suppresses tumor angiogenesis by down-regulation of vascular endothelial growth factor via hypoxic-induced factor-1α

Previous work showed that connexin 43 (Cx43) reduced the expression of hypoxic-induced factor-1α (HIF-1α) in astrocytes. HIF-1α is a master transcription factor for angiogenesis in tumor. Angiogenesis is essential for tumor progression. Here, we investigated the role of Cx43 in vascular endothelial growth factor (VEGF) production and angiogenesis in murine tumor. In the study, mouse B16F10 and 4T1 cells were overexpressed or knockdown with Cx43. The expression profiles as well as activity of the treated cells were examined. Furthermore, reduced Cx43 expression in B16F10 and 4T1 cells causes increased expression of VEGF and enhanced the proliferation of endothelial cells. On the contrary, the expression of VEGF and the proliferation of endothelial were increased in the conditioned medium of Cx43-knockdown tumor cells. We subcutaneously transplanted Cx43-overexpressing B16F10 cells into mice to evaluate the roles of Cx43 in the tumor angiogenesis. Both tumor size and the number of vessels growing in the tumor were markedly decreased compare with control group. Our findings suggest that Cx43 inhibited tumor growth by reducing angiogenesis.

Diet in dermatology: Part II. Melanoma, chronic urticaria, and psoriasis

The roles of dietary factors in aggravating, preventing, or treating skin diseases are common questions encountered in dermatology practice. Part II of this two-part series reviews dietary modifications that can potentially be utilized in the management of melanoma, chronic urticaria, and psoriasis patients. Specifically, we examine the effect of alcohol consumption and supplementation with vitamins D and E, polyunsaturated fatty acids, selenium, green tea, resveratrol, and lycopene on melanoma risk. The relationships between chronic urticaria symptoms and dietary pseudoallergens, gluten, and vitamin D are analyzed. We explore weight loss, reduced alcohol consumption, and gluten avoidance as means of reducing psoriasis-associated morbidity, as well as the possible utility of supplementation with polyunsaturated fatty acids, folic acid, vitamin D, and antioxidants. With proper knowledge of the role of diet in these cutaneous disease processes, dermatologists can better answer patient inquiries and consider implementation of dietary modifications as adjuncts to other treatments and preventative measures.