Dibutylstannanediyl (2Z,2'Z)-bis(4-(benzylamino)-4-oxobut-2-enoate inhibits prostate cancer progression by activating p38 MAPK/PPARα/SMAD4 signaling.

Organotin (IV) compounds are a focus of research for potential use in cancer chemotherapy. Here, we established anticancer profile of dibutyltin (IV) carboxylate derivatives in prostate cancer (PCa) model. We determined cytotoxicity of a library of dibutyltin (IV) carboxylate derivatives and observed that dibutylstannanediyl (2Z,2'Z)-bis(4-(benzylamino)-4-oxobut-2-enoate (Ch-620; 10 µM) was minimally toxic to normal fibroblasts. Ch-620 (1-1.25 µM) inhibited proliferation of PCa and melanoma cells on short- and long-term exposures with induction of cell cycle arrest. Ch-620 treatment increased population of apoptotic cells, as assessed by flow cytometry, and activated caspase 3. Proteomics showed activation of PPARα, with repression of SMAD4 and integrin ß5 (ITGB5) in Ch-620-treated PCa cells. Further analysis demonstrated that Ch-620 resulted in phosphorylation of p38 MAPK, upregulation of PPARα and decreased expression of SMAD4 and ITGB5 with reduced migration of PCa cells. In vivo studies in PC3M grafted athymic nude mice showed that Ch-620 (5 µg/week; 7 weeks) treatment reduced tumor growth as opposed to untreated controls. Immunoblot analysis of tumors demonstrated upregulated p-p38 MAPK and PPARα, followed by a decline in SMAD4 and ITGB5. Immunohistochemistry reinforced these results with increased caspase 3 and p-p38 MAPK and diminished Ki67 staining in Ch-620 treated animals. Taken together, our data indicate that Ch-620 inhibited proliferation of PCa through modulation of MAPK/PPARα/SMAD4 signaling. Organotin (IV) carboxylate compounds; specifically Ch-620 can be a potential anticancer agent for the treatment of PCa subject to detailed pre-clinical and clinical investigations. This unlocks prospects for the development of new tin-based drugs in cancer therapeutics.

The triphenyltin carboxylate derivative triphenylstannyl 2-(benzylcarbamoyl)benzoate impedes prostate cancer progression via modulation of Akt/FOXO3a signaling.

Prostate cancer (PCa) incidence is surging in United States and other parts of the world. Synthetic and natural compounds have been explored as potential modulators of PI3K/Akt signaling that is known to drive PCa growth. Here, we evaluated the efficacy of a series of triphenyltin (IV) carboxylate derivatives against PCa. From this library, triphenylstannyl 2-(benzylcarbamoyl)benzoate (Ch-319) resulted in reduced viability and induction of cell cycle arrest in PTEN-/- PC3M and PTEN+/- DU145 cells. In parallel, downregulation of PI3K p85/p110 subunits, dephosphorylation of Akt-1 and increase in FOXO3a expression were observed. In silico studies indicated binding interactions of Ch-319 within the ATP binding site of Akt-1 at Met281, Phe442 and Glu234 residues. Elevated po-pulation of apoptotic cells, activation of Bax and reduced Bcl2 expression indicated apoptosis by Ch-319. Pre-sensitization of PCa cells with Ch-319 augmented the effect of cabazitaxel, a commonly used taxane in patients with castration-resistant PCa. Next, in a prostate-specific PTENp-/- mice, Ch-319 showed reduced weights of genitourinary apparatus as compared to DMSO treated controls. Histological studies indicated absence of neoplastic foci in Ch-319 treated prostates. Consistently, dephosphorylation of Akt-1, reduced expression of PRAS40 and androgen receptor and increase in FOXO3a were observed in treated group. Notably, no overt organ toxicity was noted in Ch-319 treated animals. Our studies identify Akt/FOXO3a signaling as a target of triphenyltin (IV) carboxylate Ch-319 and provide a molecular basis of its growth inhibitory effect in PCa cells. We propose that Ch-319 has the potential to be developed as an anticancer agent against PCa.

Polyalthia longifolia Extract Triggers ER Stress in Prostate Cancer Cells Concomitant with Induction of Apoptosis: Insights from In Vitro and In Vivo Studies.

Plant-based therapies are being explored to prevent or treat several cancer types. The antioxidant properties of Polyalthia longifolia plant are well established. In our previous work, we demonstrated the presence of cytotoxic compounds in the methanol extract of Polyalthia longifolia (MEP) with potent activity against human leukemia cells. In the present study, we evaluated the efficacy of MEP against prostate cancer (PCa) and established the molecular basis of its effect in in vitro and in vivo models. We observed that MEP treatment resulted in a significant decrease in the growth and viability of PCa cells, associated with arrest in the G1/S phase of the cell cycle. Apoptosis was confirmed as the primary mode of MEP-induced cell death through activation of the intrinsic apoptotic machinery. Proteomic and biochemical studies identified BiP as an important target of MEP with the activation of the ER stress pathway, as a potential mechanism driving MEP-induced apoptosis. The extract exhibited strong efficacy in the PCa xenograft mouse model with significant inhibition of tumor growth and reduced tumor burden. Taken together, our findings indicate that MEP-induced apoptosis in PCa cells concomitant with the activation of the ER stress pathways results in the inhibition of tumor growth, in vitro and in vivo. Our studies provide initial evidence of the efficacy of MEP against PCa and advocate for in-depth studies in other preclinical models for its possible use in clinical settings.

Hepatic Stearoyl-CoA desaturase-1 deficiency-mediated activation of mTORC1- PGC-1α axis regulates ER stress during high-carbohydrate feeding.

Stearoyl CoA desaturase 1 (SCD1) is a key enzyme in lipogenesis as it catalyzes the synthesis of monounsaturated fatty acids (MUFAs), mainly oleate (18:1n9) and palmitoleate (16:1n7) from saturated fatty acids (SFA), stearate (18:0) and palmitate (16:0), respectively. Studies on SCD1 deficiency in mouse models demonstrated beneficial metabolic phenotypes such as reduced adiposity and improved glucose tolerance. Even though, SCD1 represents a potential target to resolve obesity related metabolic diseases; SCD1 deficiency causes endoplasmic reticulum (ER) stress and activates unfolded protein response (UPR). The induction of ER stress in response to SCD1 deficiency is governed by the cofactor, PGC-1α. However, the mechanism by which SCD1 deficiency increases PGC-1α and subsequently induces ER stress still remains elusive. The present study demonstrates that despite reduced lipogenesis, liver specific SCD1 deficiency activates the mechanistic target of rapamycin complex 1 (mTORC1) along with induction of PGC-1α and ER stress. Further, mTORC1 inhibition attenuates SCD1 deficiency-mediated induction of both PGC-1α and ER stress. Similar observations were seen by restoring endogenously synthesized oleate, but not palmitoleate, suggesting a clear mTORC1-mediated regulation of ER stress during SCD1 deficiency. Overall, our results suggest a model whereby maintaining adequate levels of hepatic oleate is required to suppress mTORC1-mediated ER stress. In addition, the activation of mTORC1 by SCD1 deficiency reveals an important function of fatty acids in regulating different cellular processes through mTORC1 signaling.

Fisetin targets YB-1/RSK axis independent of its effect on ERK signaling: insights from in vitro and in vivo melanoma models.

The anti-proliferative activity of dietary flavonoid fisetin has been validated in various cancer models. Establishing its precise mechanism of action has proved somewhat challenging given the multiplicity of its targets. We demonstrated that YB-1 promotes epithelial-to-mesenchymal transition and its inhibition suppressed tumor cell proliferation and invasion. The p90 ribosomal S6 kinase (RSK), an important ERK effector, activates YB-1 to drive melanoma growth. We found that fisetin treatment of monolayer/3-D melanoma cultures resulted in YB-1 dephosphorylation and reduced transcript levels. In parallel, fisetin suppressed mesenchymal markers and matrix-metalloproteinases in melanoma cells. Data from cell-free/cell-based systems indicated that fisetin inhibited RSK activity through binding to the kinase. Affinity studies for RSK isoforms evaluated stronger interaction for RSK2 than RSK1. Competition assays performed to monitor binding responses revealed that YB-1 and RSK2 do not compete, rather binding of fisetin to RSK2 promotes its binding to YB-1. Fisetin suppressed YB-1/RSK signaling independent of its effect on ERK, and reduced MDR1 levels. Comparable efficacy of fisetin and vemurafenib for inhibiting melanoma growth was noted albeit through divergent modulation of ERK. Our studies provide insight into additional modes of regulation through which fisetin interferes with melanoma growth underscoring its potential therapeutic efficacy in disease progression.

Targeting epithelial to mesenchymal transition in prostate cancer by a novel compound, plectranthoic acid, isolated from Ficus microcarpa.

Epithelial-to-mesenchymal transition (EMT) plays a crucial role in prostate cancer (PCa) metastasis. This has led to a surge in the efforts for identification of safer and more effective compounds which can modulate EMT and consequently inhibiting migration and invasion of PCa cells. We reported previously that Plectranthoic acid (PA), a natural compound isolated from the extracts of Ficus microcarpa, has the capability to induce cell cycle arrest and apoptosis in PCa cells. Here, we determined the effects of PA on EMT, migration, and invasion of PCa cells. Inhibition of EMT induced by different mitogens was effectively inhibited by PA treatment with subsequent decrease in migration of PCa cells. Employing a PCa cell culture model of TGF-ß-induced EMT, we showed that PA has the ability to reverse EMT. PA treatment was associated with induction of epithelial markers and decrease in the expression of mesenchymal markers in PCa cells. Proteomic analysis identified Rac1 as the major cadherin signaling protein modulated with PA treatment. In silico studies indicated that PA docked to the CH domain of NEDD9 protein with an estimated free binding energy of -7.34 Kcal/moL. Our studies revealed significant inhibition of Rac1/NEDD9 pathway in PA treated cells thereby providing a molecular basis of the inhibitory effect of PA on PCa cell migration and invasion. In conclusion, our data suggest that PA should be investigated further as an adjuvant treatment in human PCa cells, given its potential as an anti-invasive agent.

Ousting RAGE in melanoma: A viable therapeutic target?

Melanoma remains an important health concern, given the steady increase in incidence and acquisition of resistance to systemic therapies. The receptor for advanced glycation end products (RAGE) initially identified for its binding to advanced glycation end products was subsequently acknowledged as a pattern recognition receptor given its ability to recognize similar structural elements within numerous ligands. Recent studies have elucidated a plausible role of RAGE in melanoma progression through modulation of inflammatory, proliferative and invasive cellular responses. Several of its ligands including the S100 proteins and HMGB1 are being investigated for their involvement in melanoma metastasis and as potential biomarkers of the disease. Targeting RAGE signaling represents a viable therapeutic strategy which remains underexplored in cutaneous malignancies. Here we have summarized current knowledge on the functionality of RAGE with special focus on specific ligands enumerated in various in vitro and in vivo melanoma models.

Synthetic transcription elongation factors license transcription across repressive chromatin.

The release of paused RNA polymerase II into productive elongation is highly regulated, especially at genes that affect human development and disease. To exert control over this rate-limiting step, we designed sequence-specific synthetic transcription elongation factors (Syn-TEFs). These molecules are composed of programmable DNA-binding ligands flexibly tethered to a small molecule that engages the transcription elongation machinery. By limiting activity to targeted loci, Syn-TEFs convert constituent modules from broad-spectrum inhibitors of transcription into gene-specific stimulators. Here we present Syn-TEF1, a molecule that actively enables transcription across repressive GAA repeats that silence frataxin expression in Friedreich's ataxia, a terminal neurodegenerative disease with no effective therapy. The modular design of Syn-TEF1 defines a general framework for developing a class of molecules that license transcription elongation at targeted genomic loci.

Insights into Stearoyl-CoA Desaturase-1 Regulation of Systemic Metabolism.

Stearoyl-coenzyme A desaturase 1 (SCD1) is a central regulator of fuel metabolism and may represent a therapeutic target to control obesity and the progression of related metabolic diseases including type 2 diabetes and hepatic steatosis. SCD1 catalyzes the synthesis of monounsaturated fatty acids (MUFAs), mainly oleate and palmitoleate, which are important in controlling weight gain in response to feeding high carbohydrate diets. In this review, we evaluate the role of SCD1 isoform in the regulation of lipid and glucose metabolism in metabolic tissues. These highlights of recent findings are aimed toward advancing our understanding of the role of SCD1 in the development of metabolic diseases, which may help evaluate the possible health outcomes of modulating MUFA levels through targeting SCD1 activity.

Dual Inhibition of PI3K/Akt and mTOR by the Dietary Antioxidant, Delphinidin, Ameliorates Psoriatic Features In Vitro and in an Imiquimod-Induced Psoriasis-Like Disease in Mice.

AIM: The treatment of psoriasis remains elusive, underscoring the need for identifying novel disease targets and mechanism-based therapeutic approaches. We recently reported that the PI3K/Akt/mTOR pathway that is frequently deregulated in many malignancies is also clinically relevant for psoriasis. We also provided rationale for developing delphinidin (Del), a dietary antioxidant for the management of psoriasis. This study utilized high-throughput biophysical and biochemical approaches and in vitro and in vivo models to identify molecular targets regulated by Del in psoriasis. RESULTS: A kinome-level screen and Kds analyses against a panel of 102 human kinase targets showed that Del binds to three lipid (PIK3CG, PIK3C2B, and PIK3CA) and six serine/threonine (PIM1, PIM3, mTOR, S6K1, PLK2, and AURKB) kinases, five of which belong to the PI3K/Akt/mTOR pathway. Surface plasmon resonance and in silico molecular modeling corroborated Del's direct interactions with three PI3Ks (α/c2ß/γ), mTOR, and p70S6K. Del treatment of interleukin-22 or TPA-stimulated normal human epidermal keratinocytes (NHEKs) significantly inhibited proliferation, activation of PI3K/Akt/mTOR components, and secretion of proinflammatory cytokines and chemokines. To establish the in vivo relevance of these findings, an imiquimod (IMQ)-induced Balb/c mouse psoriasis-like skin model was employed. Topical treatment of Del significantly decreased (i) hyperproliferation and epidermal thickness, (ii) skin infiltration by immune cells, (iii) psoriasis-related cytokines/chemokines, (iv) PI3K/Akt/mTOR pathway activation, and (v) increased differentiation when compared with controls. Innovation and Conclusion: Our observation that Del inhibits key kinases involved in psoriasis pathogenesis and alleviates IMQ-induced murine psoriasis-like disease suggests a novel PI3K/AKT/mTOR pathway modulator that could be developed to treat psoriasis. Antioxid. Redox Signal. 26, 49-69.

Nanoencapsulation of dietary flavonoid fisetin: Formulation and in vitro antioxidant and α-glucosidase inhibition activities.

The bioactive flavonoid fisetin (FS) is a diet-derived antioxidant that is being increasingly investigated for its health-promoting effects. Unfortunately, the poor physicochemical and pharmacokinetic properties affect and limit the clinical application. In this study, novel polymeric nanoparticles (NPs), based on Poly-(ε-caprolactone) (PCL) and PLGA-PEG-COOH, encapsulating FS were formulated as suitable oral controlled release systems. Results showed NPs having a mean diameter of 140-200nm, and a percent loading of FS ranging from 70 to 82%. In vitro release studies revealed that NPs are able to protect and preserve the release of FS in gastric simulated conditions, also controlling the release in the intestinal medium. Moreover, the DPPH and ABTS scavenging capacity of FS, as well as α-glucosidase inhibition activity, that resulted about 20-fold higher than commercial Acarbose, were retained during nanoencapsulation process. In summary, our developed NPs can be proposed as an attractive delivery system to control the release of antioxidant and anti-hyperglycemic FS for nutraceutical and/or therapeutic application.

Dietary flavonoid fisetin increases abundance of high-molecular-mass hyaluronan conferring resistance to prostate oncogenesis.

We and others have shown previously that fisetin, a plant flavonoid, has therapeutic potential against many cancer types. Here, we examined the probable mechanism of its action in prostate cancer (PCa) using a global metabolomics approach. HPLC-ESI-MS analysis of tumor xenografts from fisetin-treated animals identified several metabolic targets with hyaluronan (HA) as the most affected. Efficacy of fisetin on HA was then evaluated in vitro and also in vivo in the transgenic TRAMP mouse model of PCa. Size exclusion chromatography-multiangle laser light scattering (SEC-MALS) was performed to analyze the molar mass (Mw) distribution of HA. Fisetin treatment downregulated intracellular and secreted HA levels both in vitro and in vivo Fisetin inhibited HA synthesis and degradation enzymes, which led to cessation of HA synthesis and also repressed the degradation of the available high-molecular-mass (HMM)-HA. SEC-MALS analysis of intact HA fragment size revealed that cells and animals have more abundance of HMM-HA and less of low-molecular-mass (LMM)-HA upon fisetin treatment. Elevated HA levels have been shown to be associated with disease progression in certain cancer types. Biological responses triggered by HA mainly depend on the HA polymer length where HMM-HA represses mitogenic signaling and has anti-inflammatory properties whereas LMM-HA promotes proliferation and inflammation. Similarly, Mw analysis of secreted HA fragment size revealed less HMM-HA is secreted that allowed more HMM-HA to be retained within the cells and tissues. Our findings establish that fisetin is an effective, non-toxic, potent HA synthesis inhibitor, which increases abundance of antiangiogenic HMM-HA and could be used for the management of PCa.

Exploring the molecular targets of dietary flavonoid fisetin in cancer.

The last few decades have seen a resurgence of interest among the scientific community in exploring the efficacy of natural compounds against various human cancers. Compounds of plant origin belonging to different groups such as alkaloids, flavonoids and polyphenols evaluated for their cancer preventive effects have yielded promising data, thereby offering a potential therapeutic alternative against this deadly disease. The flavonol fisetin (3,3',4',7-tetrahydroxyflavone), present in fruits and vegetables such as strawberries, apple, cucumber, persimmon, grape and onion, was shown to possess anti-microbial, anti-inflammatory, anti-oxidant and more significantly anti-carcinogenic activity when assessed in diverse cell culture and animal model systems. The purpose of this review is to update and discuss key findings obtained till date from in vitro and in vivo studies on fisetin, with special focus on its anti-cancer role. The molecular mechanism(s) described in the observed growth inhibitory effects of fisetin in different cancer cell types is also summarized. Moreover, an attempt is made to delineate the direction of future studies that could lead to the development of fisetin as a potent chemopreventive/chemotherapeutic agent against cancer.

The pentacyclic triterpenoid, plectranthoic acid, a novel activator of AMPK induces apoptotic death in prostate cancer cells.

Epidemiologic studies indicated that diabetics treated with metformin had a lower incidence of cancer than those taking other anti-diabetes drugs. This led to a surge in the efforts for identification of safer and more effective metformin mimetic compounds. The plant Ficus microcarpa is widely used for the treatment of type 2 diabetes in traditional medicine in South Asia. We obtained extracts from this plant and identified a small molecule, plectranthoic acid (PA), with potent 5'AMP-activated kinase (AMPK) activating properties far superior than metformin. AMPK is the central hub of metabolic regulation and a well-studied therapeutic target for metabolic syndrome, type-2 diabetes and cancer. We observed that treatment of prostate cancer (PCa) cells with PA inhibited proliferation and induced G0/G1 phase cell cycle arrest that was associated with up-regulation of cyclin kinase inhibitors p21/CIP1 and p27/KIP1. PA treatment suppressed mTOR/S6K signaling and induced apoptosis in PCa cells in an AMPK-dependent manner. Interestingly, PA-induced autophagy in PCa cells was found to be independent of AMPK activation. Combination studies of PA and metformin demonstrated that metformin had an inhibitory effect on PA-induced AMPK activation and suppressed PA-mediated apoptosis. Given the anti-proliferative role of PA in cancer and its potent anti-hyperglycemic activity, we suggest that PA should be explored further as a novel activator of AMPK for its ultimate use for the prevention of cancers and treatment of type 2 diabetes.

FICZ: A Messenger of Light in Human Skin.

Photosensitization, subsequent to photon absorption by chromophores present in the human skin, appears to be a key mechanism of UV-induced oxidative stress. The tryptophan photoproduct 6-formylindolo[3,2-b]carbazole (FICZ), an aryl hydrocarbon receptor ligand, has been found to be a potent UVA photosensitizer, effective at nanomolar concentrations. A novel addition to the family of endogenous photosensitizers, the precise mechanism(s) through which it mediates oxidative stress in UVA exposed skin and its response to the UVB spectrum of the solar UV flux remains unexplored. Further studies related to its functionality in the human skin, its utility as a tool against UV-induced adverse effects, and its role in inflammatory skin diseases will have the potential to open up new avenues in the realms of human skin photobiology.

Potent anti-proliferative, pro-apoptotic activity of the Maytenus royleanus extract against prostate cancer cells: evidence in in-vitro and in-vivo models.

Prostate cancer is a leading of cause of cancer related death in men. Despite intensive investment in improving early diagnosis, it often escapes timely detection. Mortality remains high in advanced stage prostate cancer where palliative care remains the only option. Effective strategies are therefore needed to prevent the occurrence and progression of the disease. Plant-derived compounds have been an important source of several clinically useful anti-cancer agents and offer an attractive approach against prostate cancer. We previously showed that the methanol extract of Maytenus royleanus (MEM) leaves and its fractions possess significant antioxidant activity with therapeutic potential against free-radical associated damages. The present study evaluated the anti-proliferative activity of MEM in the prostate cancer model system. Analysis of MEM and its various fractions revealed the presence of triterpenoids, flavonoids and tannins, conjugated to one or more polar groups and carbohydrate moieties. Further studies against known standards established the existence of caffeic acid and quercetin 3-rhamnoside in varying concentration in different MEM fractions. Time course analysis of MEM treated prostate cancer cells indicated significant decrease in cell viability, assessed by MTT and clonogenic survival assays. This was accompanied by G2 phase arrest of cell cycle, downregulation of cyclin/cdk network and increase in cdk inhibitors. MEM treated cells exhibited cleavage of Caspase-3 and PARP, and modulation of apoptotic proteins, establishing apoptosis as the primary mechanism of cell death. Notably MEM suppressed AR/PSA signaling both in prostate cancer cell cultures and in the in vivo model. Intraperitoneal injection of MEM (1.25 and 2.5 mg/ animal) to athymic nude mice implanted with androgen sensitive CWR22Rν1 cells showed significant inhibition in tumor growth and decreased serum PSA levels reciprocating in vitro findings. Taken together, our data suggest that MEM may be explored further for its potential therapeutic effects against prostate cancer progression in humans.

Dietary polyphenols in prevention and treatment of prostate cancer.

Prostate cancer is the most prevalent disease affecting males in many Western countries, with an estimated 29,480 deaths in 2014 in the US alone. Incidence rates for prostate cancer deaths have been decreasing since the early 1990s in men of all races/ethnicities, though they remain about 60% higher in African Americans than in any other group. The relationship between dietary polyphenols and the prevention of prostate cancer has been examined previously. Although results are sometimes inconsistent and variable, there is a general agreement that polyphenols hold great promise for the future management of prostate cancer. Various dietary components, including polyphenols, have been shown to possess anti-cancer properties. Generally considered as non-toxic, dietary polyphenols act as key modulators of signaling pathways and are therefore considered ideal chemopreventive agents. Besides possessing various anti-tumor properties, dietary polyphenols also contribute to epigenetic changes associated with the fate of cancer cells and have emerged as potential drugs for therapeutic intervention. Polyphenols have also been shown to affect post-translational modifications and microRNA expressions. This article provides a systematic review of the health benefits of selected dietary polyphenols in prostate cancer, especially focusing on the subclasses of polyphenols, which have a great effect on disease prevention and treatment.

Prodifferentiation, anti-inflammatory and antiproliferative effects of delphinidin, a dietary anthocyanidin, in a full-thickness three-dimensional reconstituted human skin model of psoriasis.

BACKGROUND: Psoriasis is a chronic inflammatory disorder of skin and joints for which conventional treatments that are effective in clearing the moderate-to-severe disease are limited due to long-term safety issues. This necessitates exploring the usefulness of botanical agents for treating psoriasis. We previously showed that delphinidin, a diet-derived anthocyanidin endowed with antioxidant and anti-inflammatory properties, induces normal epidermal keratinocyte differentiation and suggested its possible usefulness for the treatment of psoriasis [1]. OBJECTIVES: To investigate the effect of delphinidin (0-20 µM; 2-5 days) on psoriatic epidermal keratinocyte differentiation, proliferation and inflammation using a three-dimensional reconstructed human psoriatic skin equivalent (PSE) model. METHODS: PSEs and normal skin equivalents (NSEs) established on fibroblast-contracted collagen gels with respective psoriatic and normal keratinocytes and treated with/without delphinidin were analyzed for histology, expression of markers of differentiation, proliferation and inflammation using histomorphometry, immunoblotting, immunochemistry, qPCR and cultured supernatants for cytokine with a Multi-Analyte ELISArray Kit. RESULTS: Our data show that treatment of PSE with delphinidin induced (1) cornification without affecting apoptosis and (2) the mRNA and protein expression of markers of differentiation (caspase-14, filaggrin, loricrin, involucrin). It also decreased the expression of markers of proliferation (Ki67 and proliferating cell nuclear antigen) and inflammation (inducible nitric oxide synthase and antimicrobial peptides S100A7-psoriasin and S100A15-koebnerisin, which are often induced in psoriatic skin). ELISArray showed increased release of psoriasis-associated keratinocyte-derived proinflammatory cytokines in supernatants of the PSE cultures, and this increase was significantly suppressed by delphinidin. CONCLUSIONS: These observations provide a rationale for developing delphinidin for the management of psoriasis.

MicroRNAs and photocarcinogenesis.

As a new class of sequence-specific regulators of gene expression, the microRNAs (miRNA) form a regulatory network with growth factors and transcription factors participating in various biological processes. It is now being recognized that the various key processes involved in cancer induction are under the control of these small noncoding RNAs, which regulate ~30% of all human genes by targeting sequences in their 3'-untranslated regions. Photocarcinogenesis is a complex interplay of signaling events in the UV exposed human skin including DNA damage and repair, apoptosis, cell survival, mutations and the immune system. In this review, we have scrutinized the role of miRNAs in skin cancer biology focusing on the three most common types of skin cancer namely the basal cell carcinoma, squamous cell carcinoma and cutaneous malignant melanoma. An overview of these studies will be useful in gaining insights into the mechanisms of cancer development in the human skin. A better understanding of the functionality of miRNAs will have enormous implications to risk assessment, and to target interventions against signaling events involved in photocarcinogenesis.

Involvement of ER stress and activation of apoptotic pathways in fisetin induced cytotoxicity in human melanoma.

The prognosis of malignant melanoma remains poor in spite of recent advances in therapeutic strategies for the deadly disease. Fisetin, a dietary flavonoid is currently being investigated for its growth inhibitory properties in various cancer models. We previously showed that fisetin inhibited melanoma growth in vitro and in vivo. Here, we evaluated the molecular basis of fisetin induced cytotoxicity in metastatic human melanoma cells. Fisetin treatment induced endoplasmic reticulum (ER) stress in highly aggressive A375 and 451Lu human melanoma cells, as revealed by up-regulation of ER stress markers including IRE1α, XBP1s, ATF4 and GRP78. Time course analysis indicated that the ER stress was associated with activation of the extrinsic and intrinsic apoptotic pathways. Fisetin treated 2-D melanoma cultures displayed autophagic response concomitant with induction of apoptosis. Prolonged treatment (16days) with fisetin in a 3-D reconstituted melanoma model resulted in inhibition of melanoma progression with significant apoptosis, as evidenced by increased staining of cleaved Caspase-3 in the treated constructs. However, no difference in the expression of autophagic marker LC-3 was noted between treated and control groups. Fisetin treatment to 2-D melanoma cultures resulted in phosphorylation and activation of the multifunctional AMP-activated protein kinase (AMPK) involved in the regulation of diverse cellular processes, including autophagy and apoptosis. Silencing of AMPK failed to prevent cell death indicating that fisetin induced cytotoxicity is mediated through both AMPK-dependent and -independent mechanisms. Taken together, our studies confirm apoptosis as the primary mechanism through which fisetin inhibits melanoma cell growth and that activation of both extrinsic and intrinsic pathways contributes to fisetin induced cytotoxicity.