In vitro antitumour activity of resveratrol in human melanoma cells sensitive or resistant to temozolomide

Bitter Phytochemicals as Novel Candidates for Skin Disease Treatment

Skin diseases represent a global healthcare challenge due to their rising incidence and substantial socio-economic burden. While biological, immunological, and targeted therapies have brought a revolution in improving quality of life and survival rates for certain dermatological conditions, there remains a stringent demand for new remedies. Nature has long served as an inspiration for drug development. Recent studies have identified bitter taste receptors (TAS2Rs) in both skin cell lines and human skin. Additionally, bitter natural compounds have shown promising benefits in addressing skin aging, wound healing, inflammatory skin conditions, and even skin cancer. Thus, TAS2Rs may represent a promising target in all these processes. In this review, we summarize evidence supporting the presence of TAS2Rs in the skin and emphasize their potential as drug targets for addressing skin aging, wound healing, inflammatory skin conditions, and skin carcinogenesis. To our knowledge, this is a pioneering work in connecting information on TAS2Rs expression in skin and skin cells with the impact of bitter phytochemicals on various beneficial effects related to skin disorders.

A Review: PI3K/AKT/mTOR Signaling Pathway and Its Regulated Eukaryotic Translation Initiation Factors May Be a Potential Therapeutic Target in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant tumor developing from the esophageal squamous epithelium, and is the most common histological subtype of esophageal cancer (EC). EC ranks 10th in morbidity and sixth in mortality worldwide. The morbidity and mortality rates in China are both higher than the world average. Current treatments of ESCC are surgical treatment, radiotherapy, and chemotherapy. Neoadjuvant chemoradiotherapy plus surgical resection is recommended for advanced patients. However, it does not work in the significant promotion of overall survival (OS) after such therapy. Research on targeted therapy in ESCC mainly focus on EGFR and PD-1, but neither of the targeted drugs can significantly improve the 3-year and 5-year survival rates of disease. Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is an important survival pathway in tumor cells, associated with its aggressive growth and malignant progression. Specifically, proliferation, apoptosis, autophagy, and so on. Related genetic alterations of this pathway have been investigated in ESCC, such as PI3K, AKT and mTOR-rpS6K. Therefore, the PI3K/AKT/mTOR pathway seems to have the capability to serve as research hotspot in the future. Currently, various inhibitors are being tested in cells, animals, and clinical trials, which targeting at different parts of this pathway. In this work, we reviewed the research progress on the PI3K/AKT/mTOR pathway how to influence biological behaviors in ESCC, and discussed the interaction between signals downstream of this pathway, especially eukaryotic translation initiation factors (eIFs) and the development and progression of ESCC, to provide reference for the identification of new therapeutic targets in ESCC.

Novel Curcumin-Resveratrol Solid Nanoparticles Synergistically Inhibit Proliferation of Melanoma Cells

Polyphenols such as curcumin (Cur) and resveratrol (Res) have been recently shown to have potential to inhibit proliferation of highly aggressive melanoma cells. This study was designed to investigate the feasibility of a topical delivery system, using a solid lipid nanoparticles (SLNs) loaded delivery systems, that can enhance the skin penetration and anti-cancer efficacy of combination of these polyphenols. Negatively charged Cur-Res SLNs with a mean diameter of 180.2 ± 7.7 nm were prepared using high shear homogenization method. Cur-Res SLNs were found to be stable up to 2 weeks under 4°C. The in vitro release study showed that Res was released five time more than curcumin. The permeability of resveratrol was about 1.67 times that of curcumin from the SLN-gel formulation which was significantly (p < 0.05) lower than from SLN suspension. More than 70% of Cur-Res SLNs were bound to skin locally in a skin binding study suggesting potentially utility of Cur-Res SLNs in the treatment of localized melanoma. In fact, the electrical cell-substrate impedance sensing (ECIS) measurements suggested that Cur-Res combination has potential to stop cell migration of B16F10 melanoma cells. Furthermore, both, Cur-Res SLNs and Cur-Res solution at the ratio of 3:1 demonstrated a strong synergistic inhibition of SK-MEL-28 melanoma cell proliferation. Further evaluation of Cur-Res SLNs in vivo melanoma models are warranted to establish the clinical utility of Cur-Res formulations in melanoma therapy.

An Update on the Role of Dietary Phytochemicals in Human Skin Cancer: New Insights into Molecular Mechanisms

Human skin is continuously subjected to environmental stresses, as well as extrinsic and intrinsic noxious agents. Although skin adopts various molecular mechanisms to maintain homeostasis, excessive and repeated stresses can overwhelm these systems, leading to serious cutaneous damage, including both melanoma and non-melanoma skin cancers. Phytochemicals present in the diet possess the desirable effects of protecting the skin from damaging free radicals as well as other benefits. Dietary phytochemicals appear to be effective in preventing skin cancer and are inexpensive, widely available, and well tolerated. Multiple in vitro and in vivo studies have demonstrated the significant anti-inflammatory, antioxidant, and anti-angiogenic characteristics of dietary phytochemicals against skin malignancy. Moreover, dietary phytochemicals affect multiple important cellular processes including cell cycle, angiogenesis, and metastasis to control skin cancer progression. Herein, we discuss the advantages of key dietary phytochemicals in whole fruits and vegetables, their bioavailability, and underlying molecular mechanisms for preventing skin cancer. Current challenges and future prospects for research are also reviewed. To date, most of the chemoprevention investigations have been conducted preclinically, and additional clinical trials are required to conform and validate the preclinical results in humans.

Beta-Blockers and Berberine: A Possible Dual Approach to Contrast Neuroblastoma Growth and Progression

The use of nutraceuticals during cancer treatment is a long-lasting debate. Berberine (BBR) is an isoquinoline quaternary alkaloid extracted from a variety of medicinal plants. BBR has been shown to have therapeutic effects in different pathologies, particularly in cancer, where it affects pathways involved in tumor progression. In neuroblastoma, the most common extracranial childhood solid tumor, BBR, reduces tumor growth by regulating both stemness and differentiation features and by inducing apoptosis. At the same time, the inhibition of β-adrenergic signaling leads to a reduction in growth and increase of differentiation of neuroblastoma. In this review, we summarize the possible beneficial effects of BBR in counteracting tumor growth and progression in various types of cancer and, in particular, in neuroblastoma. However, BBR administration, besides its numerous beneficial effects, presents a few side effects due to inhibition of MAO A enzyme in neuroblastoma cells. Therefore, herein, we proposed a novel therapeutic strategy to overcome side effects of BBR administration consisting of concomitant administration of BBR together with β-blockers in neuroblastoma.

Role of Resveratrol in Regulating Cutaneous Functions

Protective role of the skin is against external insults and maintenance of electrolyte homeostasis of the body. Cutaneous dysfunction can account for the development of both cutaneous and systemic disorders. Thus, improvements in cutaneous functions can benefit a number of extracutaneous and cutaneous functions. Resveratrol, a natural ingredient, displays multiple benefits for various systems/organs, including the skin. The benefits of resveratrol for cutaneous functions include stimulation of keratinocyte differentiation and antimicrobial peptide expression, inhibition of keratinocyte proliferation and cutaneous inflammation, UV protection, anticancer, antiaging, and inhibition of melanogenesis. The mechanisms of action of resveratrol include activation of sirtuin 1 and nuclear factor erythroid 2-related factor 2, and inhibition of mitogen-activated protein kinase signaling. Evidence suggests that topical resveratrol could be a valuable alternative not only for daily skin care, but also for the prevention and treatment of various cutaneous disorders. This review summarizes the benefits of resveratrol for cutaneous functions.

Shedding light on the interaction of polydatin and resveratrol with G-quadruplex and duplex DNA: a biophysical, computational and biological approach

Among polyphenols, trans-resveratrol (tRES) and trans-polydatin (tPD) exert multiple biological effects, particularly antioxidant and antiproliferative. In this work, we have investigated the interaction of tPD with three cancer-related DNA sequences able to form G-quadruplex (G4) structures, as well as with a model duplex, and compared its behaviour with tRES. Interestingly, fluorescence analysis evidenced the ability of tPD to bind all the studied DNA systems, similarly to tRES, with tRES displaying a higher ability to discriminate G4 over duplex with respect to tPD. However, neither tRES nor tPD produced significant conformational changes of the analyzed DNA upon binding, as determined by CD-titration analysis. Computational analysis and biological data confirmed the biophysical results: indeed, molecular docking evidenced the stronger interaction of tRES with the promoter of c-myc oncogene, and immunoblotting assays revealed a reduction of c-myc expression, more effective for tRES than tPD. Furthermore, in vitro assays on melanoma cells proved that tPD was able to significantly reduce telomerase activity, and inhibit cell proliferation, with tRES producing higher effects than tPD.

P-Glycoprotein 1 Affects Chemoactivities of Resveratrol against Human Colorectal Cancer Cells

Resveratrol has been proposed to prevent tumor growth and the different steps of carcinogenesis; nevertheless, these biological effects are sometimes discordant between different cell types. Several hypotheses and works have suggested that the metabolism of resveratrol could be at the origin of a different cellular response. We show here, using colorectal tumor cell lines, that the biological effects of RSV result mainly from its carriage by carriers of the superfamily of ABC transporter, i.e., P-gP, MRP, or BCRP. Using cell lines overexpressing these different transporters, we have been able to highlight the importance of P-gP in the response of cells to RSV. These results were confirmed by invalidating the gene coding for P-gP, which restored the sensitivity of colorectal cells resistant to the polyphenol. Subsequently, the status of P-glycoprotein expression is an important element to be taken into consideration in the cytotoxic activity of resveratrol in colorectal cancer cells.

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.

Antitumour activity of resveratrol on human melanoma cells: A possible mechanism related to its interaction with malignant cell telomerase

BACKGROUND

trans-Resveratrol (tRES) is a polyphenolic stilbene found in plant products which has attracted great attention because of its antioxidant, anti-inflammatory and anticancer properties.

METHODS

The possible correlation between tRES-induced suppression of melanoma cell growth and its influence on telomerase expression has been investigated by biological assays. Moreover, in order to gain new knowledge about possible mechanisms of action of tRES as antineoplastic agent, its interaction with biologically relevant secondary structure-forming DNA sequences, its aggregation properties and copper-binding activity have been studied by CD, UV and fluorescence spectroscopies.

RESULTS

Biological assays have confirmed that growth inhibitory properties of tRES well correlate with the reduction of telomerase activity and hTERT gene transcript levels in human melanoma cells. Biophysical studies in solution have proved that tRES binds all the studied DNA model systems with low affinity, however showing high ability to discriminate G-quadruplex vs. duplex DNA. In addition, tRES has shown no propensity to form aggregates in the explored concentration range and has been found able to bind Cu²⁺ ions with a 2:1 stoichiometry.

CONCLUSIONS

From these biological and biophysical analyses it has emerged that tRES produces cytotoxic effects on human melanoma cells and, at a molecular level, is able to bind Cu²⁺ and cancer-involved G-quadruplexes, suggesting that multiple mechanisms of action could be involved in its antineoplastic activity.

GENERAL SIGNIFICANCE

Expanding the knowledge on the putative mechanisms of action of tRES as antitumour agent can help to develop novel, effective tRES-based anticancer drugs.

Synergistic anti-glioma effect of a coloaded nano-drug delivery system

The anti-glioma effect of temozolomide (Tem) is sometimes undermined by the emerging resistance. Recently, resveratrol (Res), herbal medicine extracted from grape seeds, has been demonstrated for its potential use in chemosensitization. In the current study, both these drugs were loaded simultaneously into nanoparticles with methoxy poly(ethylene glycol)-poly epsilon caprolactone (mPEG-PCL) as drug carriers in order to achieve better antitumor efficiency. Tem/Res-coloaded mPEG-PCL nanoparticles were constructed, characterized, and tested for antitumor effect on glioma cells by using in vitro and xenograft model system. The nanoparticle constructs were satisfactory with drug loading content (Res =~12.4%; Tem =~9.3%) and encapsulation capacity of >85% for both the drugs. In addition, the coencapsulation led to better in vitro stability of the nanoparticles than Tem-loaded nanoparticles. An in vitro uptake study demonstrated a high uptake efficiency of the nanoparticles by glioma cells. The synergistic antitumor effect against glioma cells was observed in the combinational treatment of Res and Tem. Tem/Res-coloaded nanoparticles induced higher apoptosis in U87 glioma cells as compared to cells treated by the combination of free drugs. Tem/Res-coloaded particles caused more effective inhibition of phosphor-Akt, leading to upregulation of the downstream apoptotic proteins. In addition, the in vivo study showed the superior tumor delaying effect of coloaded nanoparticles than that of free drug combination. These results suggest that Tem/Res-coloaded nanoparticles could be a potential useful chemotherapeutic formulation for glioma therapy.

Use of Polyphenolic Compounds in Dermatologic Oncology

Polyphenols are a widely used class of compounds in dermatology. While phenol itself, the most basic member of the phenol family, is chemically synthesized, most polyphenolic compounds are found in plants and form part of their defense mechanism against decomposition. Polyphenolic compounds, which include phenolic acids, flavonoids, stilbenes, and lignans, play an integral role in preventing the attack on plants by bacteria and fungi, as well as serving as cross-links in plant polymers. There is also mounting evidence that polyphenolic compounds play an important role in human health as well. One of the most important benefits, which puts them in the spotlight of current studies, is their antitumor profile. Some of these polyphenolic compounds have already presented promising results in either in vitro or in vivo studies for non-melanoma skin cancer and melanoma. These compounds act on several biomolecular pathways including cell division cycle arrest, autophagy, and apoptosis. Indeed, such natural compounds may be of potential for both preventive and therapeutic fields of cancer. This review evaluates the existing scientific literature in order to provide support for new research opportunities using polyphenolic compounds in oncodermatology.

Downregulation of proinflammatory cytokines in HTLV-1-infected T cells by Resveratrol

BACKGROUND

Human T-cell leukemia virus (HTLV-1) is a lymphotropic retrovirus associated to adult T cell leukemia (ATL) and to non-neoplastic inflammatory conditions affecting the central nervous system, lung or skin. The inflammatory disorders associated to HTLV-1 are mediated by different proinflammatory cytokines as IL-1α, IL-6, TNF-α. The release and the role of IL-17 is still debated. Aims of this study were to analyze IL-17 induction by HTLV-1 infection and to determine whether resveratrol (RES) is able to down regulate the pathway of cytokines production either in HTLV-1 chronically infected MT-2 cell line or in human CD4+ cells infected in vitro with HTLV-1.

METHODS

MT-2 and HTLV-1 infected CD4+ cells were analyzed for proinflammatory cytokine production before or after RES treatment. The concentrations of IL-17, IL-1α, IL-6, and TNF-α were measured in cell culture supernatants by ELISA and SearchLight™ technology. The IL-17 mRNA expression was evaluated by RT-PCR. NF-kB activation was detected by non-radioactive, Electro Mobility Shift Assay (EMSA). HTLV-1 RNA expression was detected by Real-time-PCR (RQ-PCR).

RESULTS

We found that RES is capable of inducing a dose-dependent inhibition of IL-1α, IL-6 and TNF-α production in vitro and can down regulate the expression of IL-17 at both mRNA and protein levels in HTLV-1 infected cells. This effect was associated with a dose-dependent inhibition of the of the nuclear factor kappa-B (NF-kB) activity. Conversely, RES did not apparently affect HTLV-1 proliferation.

CONCLUSIONS

These results support the anti-inflammatory properties of RES, suggesting that it might be a useful therapeutic agent for the treatment of HTLV-1 related inflammatory diseases.

Aloe-emodin exerts a potent anticancer and immunomodulatory activity on BRAF-mutated human melanoma cells

Aim of this study was to extend the knowledge on the antineoplastic effect of aloe-emodin (AE), a natural hydroxyanthraquinone compound, both in metastatic human melanoma cell lines and in primary stem-like cells (melanospheres). Treatment with AE caused reduction of cell proliferation and induction of SK-MEL-28 and A375 cells differentiation, characterized by a marked increase of transamidating activity of transglutaminase whose expression remained unmodified. In vitro antimetastatic property of AE was evaluated by adhesion and Boyden chamber invasion assays. The effect of AE on melanoma cytokines/chemokines production was determined by a multiplex assay: interestingly AE showed an immunomodulatory activity through GM-CSF and IFN-γ production. We report also that AE significantly reduced the proliferation, stemness and invasive potential of melanospheres. Moreover, AE treatment significantly enhanced dabrafenib (a BRAF inhibitor) antiproliferative activity in BRAF mutant cell lines. Our results confirm that AE possesses remarkable antineoplastic properties against melanoma cells, indicating this anthraquinone as a promising agent for differentiation therapy of cancer, or as adjuvant in chemotherapy and targeted therapy. Further, its mechanisms of action support a potential efficacy of AE treatment to counteract resistance of BRAF-mutated melanoma cells to target therapy.

Polydatin, a natural precursor of resveratrol, induces cell cycle arrest and differentiation of human colorectal Caco-2 cell

Background

Human colon adenocarcinoma cells are resistant to chemotherapeutic agents, such as anthracyclines, that induce death by increasing the reactive oxygen species. A number of studies have been focused on chemo-preventive use of resveratrol as antioxidant against cardiovascular diseases, aging and cancer. While resveratrol cytotoxic action was due to its pro-oxidant properties. In this study, we investigate whether the Resveratrol (trans-3,5,49-trihydroxystilbene) and its natural precursor Polydatin (resveratrol-3-O-b-mono- D-glucoside, the glycoside form of resveratrol) combination, might have a cooperative antitumor effect on either growing or differentiated human adenocarcinoma colon cancer cells.

Methods

The polydatin and resveratrol pharmacological interaction was evaluated in vitro on growing and differentiated Caco-2 cell lines by median drug effect analysis calculating a combination index with CalcuSyn software. We have selected a synergistic combination and we have evaluated its effect on the biological and molecular mechanisms of cell death.

Results

Simultaneous exposure to polydatin and resveratrol produced synergistic antiproliferative effects compared with single compound treatment. We demonstrated that polydatin alone or in combination with resveratrol at 3:1 molar ratio synergistically modulated oxidative stress, cell cycle, differentiation and apoptosis. Worthy of note treatment with polydatin induced a nuclear localization and decreased expression of heat shock protein 27, and vimentin redistributed within the cell.

Conclusions

From morphological, and biochemical outcome we obtained evidences that polydatin induced a transition from a proliferative morphology to cell-specific differentiated structures and caused human CaCo-2 cell death by induction of apoptosis. Our data suggest the potential use of polydatin in combination chemotherapy for human colon cancer.

Resveratrol-induced apoptosis is enhanced by inhibition of autophagy in esophageal squamous cell carcinoma

The anti-cancer activity of resveratrol in human esophageal squamous cell carcinoma (ESCC) was investigated focusing on the role of autophagy and its effects on apoptotic cell death. We demonstrated that resveratrol inhibits ESCC cell growth in a dose-dependent manner by inducing cell cycle arrest at the sub-G1 phase and resulting in subsequent apoptosis. Mechanistically, resveratrol-induced autophagy in the ESCC cells is AMPK/mTOR pathway independent. Since both pharmacological and genetic inhibition of autophagy enhanced the resveratrol-induced cytotoxicity to the ESCC cells, this provided a novel strategy in potentiating the anti-cancer effects of resveratrol and other chemotherapeutic reagents in ESCC cancer treatment.

Resveratrol abrogates the temozolomide-induced G2 arrest leading to mitotic catastrophe and reinforces the temozolomide-induced senescence in glioma cells

Background

Temozolomide (TMZ) is the most widely used drug to treat glioblastoma (GBM), which is the most common and aggressive primary tumor of the Central Nervous System and one of the hardest challenges in oncotherapy. TMZ is an alkylating agent that induces autophagy, apoptosis and senescence in GBM cells. However, therapy with TMZ increases survival after diagnosis only from 12 to 14.4 months, making the development of combined therapies to treat GBM fundamental. One candidate for GBM therapy is Resveratrol (Rsv), which has additive toxicity with TMZ in several glioma cells in vitro and in vivo. However, the mechanism of Rsv and TMZ additive toxicity, which is the aim of the present work, is not clear, especially concerning cell cycle dynamics and long term effects.

Methods

Glioma cell lines were treated with Rsv and TMZ, alone or in combinations, and the induction and the role of autophagy, apoptosis, cell cycle dynamics, protein expression and phosphorylation status were measured. We further evaluated the long term senescence induction and clonogenic capacity.

Results

As expected, temozolomide caused a G2 cell cycle arrest and extensive DNA damage response. Rsv did not reduced this response, even increasing pATM, pChk2 and gammaH2Ax levels, but abrogated the temozolomide-induced G2 arrest, increasing levels of cyclin B and pRb(S807/811) and reducing levels of pWee1(S642) and pCdk1(Y15). This suggests a cellular state of forced passage through G2 checkpoint despite large DNA damage, a scenario that may produce mitotic catastrophe. Indeed, the proportion of cells with high nuclear irregularity increased from 6 to 26% in 48 h after cotreatment. At a long term, a reduction in clonogenic capacity was observed, accompanied by a large induction of senescence.

Conclusion

The presence of Rsv forces cells treated with TMZ through mitosis leading to mitotic catastrophe and senescence, reducing the clonogenic capacity of glioma cells and increasing the chronic effects of temozolomide.

Anti-tumor and immunomodulatory activity of resveratrol in vitro and its potential for combining with cancer immunotherapy

We evaluated the anti-tumor effect of Resveratrol (RV) on M21 and NXS2 tumor cell lines and its immunosuppressive activity on human and murine immune cells to determine the potential for combining RV and immunotherapy. In vitro, concentrations of RV≥25 mcM, inhibited cell proliferation, blocked DNA synthesis and induced G1 phase arrest in tumor and immune cells. RV at 12-50 mcM inhibited antibody dependent cell mediated cytotoxicity (ADCC) of tumor cells facilitated by the hu14.18-IL2 immunocytokine (IC). The in vivo anti-tumor and immunomodulating activity of RV given systemically were assessed in mice. Results showed that this RV regimen inhibited the growth of NXS2 tumors in vivo but did not appear to interfere with blood cell count, splenocyte or macrophage function. Thus, RV may be a candidate for combining with immunotherapy.

Autophagy interplay with apoptosis and cell cycle regulation in the growth inhibiting effect of resveratrol in glioma cells

Prognosis of patients with glioblastoma (GBM) remains very poor, thus making the development of new drugs urgent. Resveratrol (Rsv) is a natural compound that has several beneficial effects such as neuroprotection and cytotoxicity for several GBM cell lines. Here we evaluated the mechanism of action of Rsv on human GBM cell lines, focusing on the role of autophagy and its crosstalk with apoptosis and cell cycle control. We further evaluated the role of autophagy and the effect of Rsv on GBM Cancer Stem Cells (gCSCs), involved in GBM resistance and recurrence. Glioma cells treated with Rsv was tested for autophagy, apoptosis, necrosis, cell cycle and phosphorylation or expression levels of key players of these processes. Rsv induced the formation of autophagosomes in three human GBM cell lines, accompanied by an upregulation of autophagy proteins Atg5, beclin-1 and LC3-II. Inhibition of Rsv-induced autophagy triggered apoptosis, with an increase in Bax and cleavage of caspase-3. While inhibition of apoptosis or autophagy alone did not revert Rsv-induced toxicity, inhibition of both processes blocked this toxicity. Rsv also induced a S-G2/M phase arrest, accompanied by an increase on levels of pCdc2(Y15), cyclin A, E and B, and pRb (S807/811) and a decrease of cyclin D1. Interestingly, this arrest was dependent on the induction of autophagy, since inhibition of Rsv-induced autophagy abolishes cell cycle arrest and returns the phosphorylation of Cdc2(Y15) and Rb(S807/811), and levels of cyclin A, and B to control levels. Finally, inhibition of autophagy or treatment with Rsv decreased the sphere formation and the percentage of CD133 and OCT4-positive cells, markers of gCSCs. In conclusion, the crosstalk among autophagy, cell cycle and apoptosis, together with the biology of gCSCs, has to be considered in tailoring pharmacological interventions aimed to reduce glioma growth using compounds with multiple targets such as Rsv.

Botanicals for the prevention and treatment of cutaneous melanoma

Cutaneous melanoma, a cancer of melanocytes, when detected at later stages is arguably one of the most lethal cancers and the cause of more years of lost life than any other cancer among young adults. There is no standard therapy for advanced-stage melanoma and the median survival time for patients with metastatic melanoma is <1 yr. An urgent need for novel strategies against melanoma has directed research towards the development of new chemotherapeutic and biologic agents that can target the tumor by several different mechanisms. Recently, several dietary agents are being investigated for their role in the prevention and treatment of various forms of cancer and may represent the future modality of the treatment. Here, we have reviewed emerging data on botanicals that are showing promise for their potential inhibitory effect against cutaneous melanoma.

The anti-tumor effect of resveratrol alone or in combination with immunotherapy in a neuroblastoma model

We investigated the anti-tumor effect of peritumoral resveratrol in combination with immunotherapy in vivo in neuroblastoma-bearing mice. Subcutaneous NXS2 tumors were induced in A/J mice. On day 10, some mice received 15 mcg of intravenous immunocytokine for 5 days, mice received 20 mg of peritumoral resveratrol twice a week (starting on day 12) for a total of 5 injections, and a separate group received a combination of both regimens. Tumor progression and survival were assessed every 3-4 days. Blood and primary tumor tissue samples were collected on day 20 for Complete Blood Count and CD45 immunohistochemistry and histology, respectively. The primary tumor regressed in all mice receiving peritumoral resveratrol. Most of these mice receiving peritumoral resveratrol alone developed metastatic tumors and recurrence of the primary tumor after cessation of therapy. When resveratrol and immunocytokine regimens were combined, 61% of the mice receiving this combination therapy resolved their primary tumors and survived without developing metastatic tumors, compared to 15 and 13% receiving resveratrol or immunocytokine alone, respectively. None of the therapeutic regimes prevented lymphocyte infiltration or affected the complete blood count. Greater necrosis was observed microscopically in tumors from mice receiving the combination therapy. These results demonstrate that the combination therapy of peritumoral resveratrol plus intravenous immunocytokine provides better anti-tumor effects in this model than either therapy alone.

Natural products and their role in cancer therapy

This paper documented several natural products that have antineoplastic activities. Detailed descriptions of the mechanism of action of these products are given. Side effects of these natural products are also described. Based on these side effect profiles and their benefits, these natural products could be used as adjuvant cancer therapies. Traditional anticancer agents usually have debilitating side effects. These natural products would be of great benefit due to their anticancer activities. Additionally, some of these natural products can work proactively in preventing cancer formation with their chemopreventive properties. Incorporation into diet can be recommended after discussion with physician and other health care professionals.

Current research and development of chemotherapeutic agents for melanoma

Cutaneous malignant melanoma is the most lethal form of skin cancer and an increasingly common disease worldwide. It remains one of the most treatment-refractory malignancies. The current treatment options for patients with metastatic melanoma are limited and in most cases non-curative. This review focuses on conventional chemotherapeutic drugs for melanoma treatment, by a single or combinational agent approach, but also summarizes some potential novel phytoagents discovered from dietary vegetables or traditional herbal medicines as alternative options or future medicine for melanoma prevention. We explore the mode of actions of these natural phytoagents against metastatic melanoma.

Combined treatment with Ad-hTRAIL and DTIC or SAHA is associated with increased mitochondrial-mediated apoptosis in human melanoma cell lines

BACKGROUND

Currently, dacarbazine (DTIC) is the only approved systemic treatment for metastatic malignant melanoma. However, the modest treatment effect encourages studies on novel therapeutic molecules, delivery systems and combination therapies. Full-length TRAIL, delivered from an adenoviral vector (Ad-hTRAIL), was studied in combination with DTIC or the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) in human melanoma cell lines.

METHODS

The cytotoxic potential of the combination treatments was assessed by cell viability measurements and CalcuSyn analysis. Involvement of apoptosis was analyzed by TUNEL staining, mitochondrial membrane potential measurements, and activation and expression levels of caspases and other mediators of apoptosis.

RESULTS

Ad-hTRAIL in combination with DTIC or SAHA resulted in additive or synergistic growth inhibition compared to each treatment used as single agent. Both combinations augmented apoptosis, which was mediated through the death receptor (DR) pathway by enhanced activation of caspase-8, and through increased loss of mitochondrial integrity. Provoked cleavage of Bid, which bridges the extrinsic and intrinsic apoptosis pathways, and downregulation of the anti-apoptotic mediators Bcl-X(L), Mcl-1 and XIAP (but not Bcl-2) were critical contributing factors. Increased levels of DR4 and DR5 were not a common underlying mechanism as DTIC did not affect the levels of either of the receptors. However, SAHA-induced expression of DR4 may have reduced the TRAIL resistance in the SKMEL-28 cell line.

CONCLUSION

Administration of Ad-hTRAIL in combination with DTIC or SAHA enhances apoptosis in human melanoma cell lines, and suggests that the therapeutic potential of such treatment strategies should be further evaluated for possible clinical use.

Cell surface F1Fo ATP synthase: a new paradigm?

The mitochondrial F1Fo adenosine triphosphate (ATP) synthase is one of the most thoroughly studied enzyme complexes known. Yet, a number of new observations suggesting that the enzyme is also located on the cell surface necessitate further investigation. While the mitochondrial synthase utilizes the proton gradient generated by oxidative phosphorylation to power ATP synthesis, the cell surface synthase has instead been implicated in numerous activities, including the mediation of intracellular pH, cellular response to antiangiogenic agents, and cholesterol homeostasis. Intriguingly, a common thread uniting these various models of cell surface ATP synthase functions is the apparently caveolar distribution of the enzyme. Recent studies concerning the cell surface ATP synthase manifest applications in the regulation of serum cholesterol levels, cellular proliferation and antitumor strategies. This review addresses the expression, interactions, functions, and consequences of inhibition of cell surface ATP synthase, an enzyme now displaying a shift in paradigm, as well as of location.

Angiostatin's molecular mechanism: aspects of specificity and regulation elucidated

Tumor growth requires the development of new vessels that sprout from pre-existing normal vessels in a process known as "angiogenesis" [Folkman (1971) N Engl J Med 285:1182-1186]. These new vessels arise from local capillaries, arteries, and veins in response to the release of soluble growth factors from the tumor mass, enabling these tumors to grow beyond the diffusion-limited size of approximately 2 mm diameter. Angiostatin, a naturally occurring inhibitor of angiogenesis, was discovered based on its ability to block tumor growth in vivo by inhibiting the formation of new tumor blood vessels [O'Reilly et al. (1994a) Cold Spring Harb Symp Quant Biol 59:471-482]. Angiostatin is a proteolytically derived internal fragment of plasminogen and may contain various members of the five plasminogen "kringle" domains, depending on the exact sites of proteolysis. Different forms of angiostatin have measurably different activities, suggesting that much remains to be elucidated about angiostatin biology. A number of groups have sought to identify the native cell surface binding site(s) for angiostatin, resulting in at least five different binding sites proposed for angiostatin on the surface of endothelial cells (EC). This review will consider the data supporting all of the various reported angiostatin binding sites and will focus particular attention on the angiostatin binding protein identified by our group: F(1)F(O) ATP synthase. There have been several developments in the quest to elucidate the mechanism of action of angiostatin and the regulation of its receptor. The purpose of this review is to describe the highlights of research on the mechanism of action of angiostatin, its' interaction with ATP synthase on the EC surface, modulators of its activity, and issues that should be explored in future research related to angiostatin and other anti-angiogenic agents.