Dasatinib, a second-generation tyrosine kinase inhibitor, induces melanogenesis via ERK-CREB-MITF-tyrosinase signaling in normal human melanocytes

Dasatinib: a potential tyrosine kinase inhibitor to fight against multiple cancer malignancies

Dasatinib is the 2nd generation TKI (Tyrosine Kinase Inhibitor) having the potential to treat numerous forms of leukemic and cancer patients and it is 300 times more potent than imatinib. Cancer is the major cause of death globally and need to enumerate novel strategies to coping with it. Various novel therapeutics introduced into the market for ease in treating various forms of cancer. We reviewed and evaluated all the related aspects of dasatinib, which can enhance the knowledge about dasatinib therapeutics methodology, pharmacodynamic and pharmacokinetics, side effects, advantages, disadvantages, various kinds of interactions and its novel formulations as well.

The Hypopigmentation Mechanism of Tyrosinase Inhibitory Peptides Derived from Food Proteins: An Overview

Skin hyperpigmentation resulting from excessive tyrosinase expression has long been a problem for beauty lovers, which has not yet been completely solved. Although researchers are working on finding effective tyrosinase inhibitors, most of them are restricted, due to cell mutation and cytotoxicity. Therefore, functional foods are developing rapidly for their good biocompatibility. Food-derived peptides have been proven to display excellent anti-tyrosinase activity, and the mechanisms involved mainly include inhibition of oxidation, occupation of tyrosinase’s bioactive site and regulation of related gene expression. For anti-oxidation, peptides can interrupt the oxidative reactions catalyzed by tyrosinase or activate an enzyme system, including SOD, CAT, and GSH-Px to scavenge free radicals that stimulate tyrosinase. In addition, researchers predict that peptides probably occupy the site of the substrate by chelating with copper ions or combining with surrounding amino acid residues, ultimately inhibiting the catalytic activity of tyrosinase. More importantly, peptides reduce the tyrosinase expression content, primarily through the cAMP/PKA/CREB pathway, with PI3K/AKT/GSK3β, MEK/ERK/MITF and p38 MAPK/CREB/MITF as side pathways. The objective of this overview is to recap three main mechanisms for peptides to inhibit tyrosinase and the emerging bioinformatic technologies used in developing new inhibitors.

2-Hydroxyestradiol Overcomes Mesenchymal Stem Cells-Mediated Platinum Chemoresistance in Ovarian Cancer Cells in an ERK-Independent Fashion

Ovarian cancer (OC) is the second most common type of gynecological malignancy. Platinum (Pt)-based chemotherapy is the standard of care for OC, but toxicity and acquired chemoresistance has proven challenging. Recently, we reported that sensitivity to platinum was significantly reduced in a co-culture of OC cells with MSC. To discover compounds capable of restoring platinum sensitivity, we screened a number of candidates and monitored ability to induce PARP cleavage. Moreover, we monitored platinum uptake and expression of ABC transporters in OC cells. Our results showed that 2-hydroxyestradiol (2HE2), a metabolite of estradiol, and dasatinib, an Abl/Src kinase inhibitor, were significantly effective in overcoming MSC-mediated platinum drug resistance. Dasatinib activity was dependent on ERK1/2 activation, whereas 2HE2 was independent of the activation of ERK1/2. MSC-mediated platinum drug resistance was accompanied by reduced intracellular platinum concentrations in OC cells. Moreover, MSC co-cultured with OC cells resulted in downregulation of the expression of cellular transporters required for platinum uptake and efflux. Exposure to 2HE2 and other modulators resulted in an increase in intracellular platinum concentrations. Thus, 2HE2 and dasatinib might act as sensitizers to restore platinum drug sensitivity to OC cells and thus to limit TME-mediated chemoresistance in OC.

The Anticancer Potential of Doxycycline and Minocycline-A Comparative Study on Amelanotic Melanoma Cell Lines

Malignant melanoma is still a serious medical problem. Relatively high mortality, a still-growing number of newly diagnosed cases, and insufficiently effective methods of therapy necessitate melanoma research. Tetracyclines are compounds with pleiotropic pharmacological properties. Previously published studies on melanotic melanoma cells ascertained that minocycline and doxycycline exerted an anti-melanoma effect. The purpose of the study was to assess the anti-melanoma potential and mechanisms of action of minocycline and doxycycline using A375 and C32 human amelanotic melanoma cell lines. The obtained results indicate that the tested drugs inhibited proliferation, decreased cell viability, and induced apoptosis in amelanotic melanoma cells. The treatment caused changes in the cell cycle profile and decreased the intracellular level of reduced thiols and mitochondrial membrane potential. The exposure of A375 and C32 cells to minocycline and doxycycline triggered the release of cytochrome c and activated initiator and effector caspases. The anti-melanoma effect of analyzed drugs appeared to be related to the up-regulation of ERK1/2 and MITF. Moreover, it was noticed that minocycline and doxycycline increased the level of LC3A/B, an autophagy marker, in A375 cells. In summary, the study showed the pleiotropic anti-cancer action of minocycline and doxycycline against amelanotic melanoma cells. Considering all results, it could be concluded that doxycycline was a more potent drug than minocycline.

Skin senescence: mechanisms and impact on whole-body aging

The skin is the largest organ and has a key protective role. Similar to any other tissue, the skin is influenced not only by intrinsic/chronological aging, but also by extrinsic aging, triggered by environmental factors that contribute to accelerating the skin aging process. Aged skin shows structural, cellular, and molecular changes and accumulation of senescent cells. These senescent cells can induce or accelerate the age-related dysfunction of other nearby cells from the skin, or from different origins. However, the extent and underlying mechanisms remain unknown. In this opinion, we discuss the possible relevant role of skin senescence in the induction of aging phenotypes to other organs/tissues, contributing to whole-body aging. Moreover, we suggest that topical administration of senolytics/senotherapeutics could counteract the overall whole-body aging phenotype.

Comparative study of the photo‑protective and anti‑melanogenic properties of gomisin D, J and O

Skin cancer is the most common human malignancy worldwide and solar ultraviolet (UV) radiation is known to serve an important role in its pathogenesis. Natural candidate compounds with antioxidant, photoprotective and anti-melanogenic effects were investigated against the background of skin photoprotective and anti-melanogenic properties. Gomisin D, J and O are dibenzocyclooctadiene lignans present in Kadsura medicinal plants and possess several pharmacological activities. In this study, the functions and mechanisms underlying the effects of gomisin D, J and O in UVA-and UVB-irradiated keratinocytes and α-melanocyte stimulating hormone (α-MSH)-stimulated melanocytes were explored. Following UVA and UVB irradiation, keratinocytes were treated with gomisin D, J and O, and keratinocyte viability, lactate dehydrogenase (LDH) release, intracellular reactive oxygen species (ROS) production and apoptosis were examined. The results demonstrated that gomisin D and J improved keratinocyte viability and reduced LDH release under UVA and UVB irradiation. Intracellular ROS production induced by UVA and UVB irradiation was suppressed by gomisin D and J. In addition, Annexin V and TUNEL staining analysis indicated that gomisin D and J have significant anti-apoptotic effects on UVA-and UVB-irradiated keratinocytes. After α-MSH stimulation, melanocytes were treated with gomisin D, J and O, and the changes in melanocyte viability, intracellular melanin content, intracellular tyrosinase activity, and mechanisms underlying these changes were examined. Gomisin D markedly inhibited the α-MSH-induced increase in intracellular melanin content and tyrosinase activity. Mechanistically, gomisin D reduced the protein and mRNA expression levels of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1 and TRP-2 in α-MSH-stimulated melanocytes. In addition, gomisin D markedly downregulated α-MSH-induced phosphorylation of protein kinase A and cAMP response element binding protein, which are known to be present upstream of the MITF, tyrosinase, TRP-1 and TRP-2 genes. Overall, gomisin D has photoprotective and anti-melanogenic effects; these findings provide a basis for the production of potential brightening and photoprotective agents using natural compounds such as gomisin D.

Increase in NO causes osteoarthritis and chondrocyte apoptosis and chondrocyte ERK plays a protective role in the process

BACKGROUND

Nitric oxide (NO) and reactive oxygen species (ROS) play an important role in the pathology of human osteoarthritis (OA). Ankylosing spondylitis (AS) and atypical OA have similar clinical manifestations and often require differential diagnosis. The mechanism is however not totally clear yet. This study aims to investigate the effects of excessive NO-ROS in OA patients and the effects of extracellular signal-regulated kinases (ERK) pathway in NO-induced apoptosis of chondrocytes during OA progress.

METHODS AND RESULTS

Serum samples from OA or AS as pathological control patients and healthy controls were collected for NO and related chemical measurements. The rabbit articular chondrocytes were cultured in vitro, and NO was applied by Sodium Nitroprusside (SNP) in culture medium to mimic OA condition in patients. The level of SNP-evoked chondrocyte apoptosis with or without PD98059 (ERK-specific inhibitor) was evaluated by TUNEL assay, Annexin V flow cytometry and Western blotting. The activity and mRNA expression of caspase-3 in chondrocytes were measured by assay kits and RT-PCR. The levels of NO and malondialdehyde (MDA) in serum were significantly higher in OA patients, while only MDA was significantly higher in AS patients. However, the level of superoxide dismutase (SOD) was lower in both OA and AS patients. SNP induced chondrocyte apoptosis was enhanced by PD98059 with increased protein expression and functional activity of caspase-3.

CONCLUSIONS

The increase in nitric oxide occurs specifically in OA patients. ERK pathway may play a protective role on the NO-induced chondrocyte apoptosis, and inhibition of ERK pathway enhances the NO-induced apoptosis.

Highlights on selected growth factors and their receptors as promising anticancer drug targets

Growth factor receptors (GFRs) and receptor tyrosine kinases (RTK) are groups of proteins mediating a plethora of physiological processes, including cell growth, proliferation, survival, differentiation and migration. Under certain circumstances, expression of GFRs and subsequently their downstream kinase signaling are deregulated by genetic, epigenetic, and somatic changes leading to uncontrolled cell division in many human diseases, most notably cancer. Cancer cells rely on growth factors to sustain the increasing need to cell division and metabolic reprogramming through cancer-associated activating mutations of their receptors (i.e., GFRs). In this review, we highlight the recent advances of selected GFRs and their ligands (growth factors) in cancer with emphasis on structural and functional differences. We also interrogate how overexpression and/or hyperactivation of GFRs contribute to cancer initiation, development, progression, and resistance to conventional chemo- and radiotherapies. Novel approaches are being developed as anticancer agents to target growth factor receptors and their signaling pathways in different cancers. Here, we illustrate how the current knowledge of GFRs biology, and their ligands lead to development of targeted therapies to inhibit and/or block the activity of growth factors, GFRs and downstream kinases to treat diseases such as cancer.

A Comparative Study on Photo-Protective and Anti-Melanogenic Properties of Different Kadsura coccinea Extracts

Kadsura coccinea (KC), a beneficial plant for human health, has been used for centuries in China, Thailand, and Korea in folk medicine and food. There is evidence supporting the biological effects of highly bioactive ingredients in KC such as lignans, triterpenoids, flavonoids, phenolic acids, steroids, and amino acids. In this study, we aimed to explore the effects, functions, and mechanisms of the extracts from KC root (KCR), stem (KCS), leaf (KCL), and fruit (KCF) in UVA and UVB-irradiated keratinocytes and α-melanocyte stimulating hormone (α-MSH)-stimulated melanocytes. First, the total polyphenol and flavonoid contents of KCR, KCS, KCL, and KCF and their radical scavenging activities were investigated. These parameters were found to be in the following order: KCL > KCR > KCS > KCF. UVA and UVB-irradiated keratinocytes were treated with KCR, KCS, KCL, and KCF, and keratinocyte viability, LDH release, intracellular ROS production, and apoptosis were examined. Our results demonstrated that KC extracts improved keratinocyte viability and reduced LDH release, intracellular ROS production, and apoptosis in the presence UVA and UVB irradiation. The overall photoprotective activity of the KC extracts was confirmed in the following order: KCL > KCR > KCS > KCF. Moreover, KC extracts significantly decreased the intracellular melanin content and tyrosinase activity in α-MSH-stimulated melanocytes. Mechanistically, KC extracts reduced the protein and mRNA expression levels of tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2) in α-MSH-stimulated melanocytes. In addition, these extracts markedly downregulated myophthalmosis-related transcription factor expression and cAMP-related binding protein phosphorylation, which is upstream of the regulation of Tyrosinase, TRP-1, and TRP-2. The overall anti-melanogenic activity of the KC extracts was established in the following order. KCL > KCR > KCS > KCF. Overall, the KC extracts exert photoprotective and anti-melanogenic effects, providing a basis for developing potential skin-whitening and photoprotective agents.