Born to be alive: a role for the BCL-2 family in melanoma tumor cell survival, apoptosis, and treatment

Melanocortin receptor 4 as a new target in melanoma therapy: Anticancer activity of the inhibitor ML00253764 alone and in association with B-raf inhibitor vemurafenib

The aim of our study is to investigate in vitro and in vivo MC4R as a novel target in melanoma using the selective antagonist ML00253764 (ML) alone and in combination with vemurafenib, a B-rafV600E inhibitor. The human melanoma B-raf mutated A-2058 and WM 266-4 cell lines were used. An MC4R null A-2058 cell line was generated using a CRISPR/Cas9 system. MC4R protein expression was analysed by western blotting, immunohistochemistry, and immunofluorescence. Proliferation and apoptotic assays were performed with ML00253764, whereas the synergism with vemurafenib was evaluated by the combination index (CI) and Loewe methods. ERK1/2 phosphorylation and BCL-XL expression were quantified by western blot. In vivo experiments were performed in Athymic Nude-Foxn1nu male mice, injecting subcutaneously melanoma cells, and treating animals with ML, vemurafenib and their concomitant combination. Comet and cytome assays were performed. Our results show that human melanoma cell lines A-2058 and WM 266-4, and melanoma human tissue, express functional MC4R receptors on their surface. MC4R receptors on melanoma cells can be inhibited by the selective antagonist ML, causing antiproliferative and proapoptotic activity through the inhibition of phosphorylation of ERK1/2 and a reduction of BCL-XL. The concomitant combination of vemurafenib and ML caused a synergistic effect on melanoma cells in vitro and inhibited in vivo tumor growth in a preclinical model, without causing mouse weight loss or genotoxicity. Our original research contributes to the landscape of pharmacological treatments for melanoma, providing MC4R antagonists as drugs that can be added to established therapies.

Therapeutic potential of marine peptides in malignant melanoma

Malignant melanoma is the most dangerous type of skin cancer. It is becoming more common globally and is increasingly resistant to treatment options. Despite extensive research into its pathophysiology, there are still no proven cures for metastatic melanoma. Unfortunately, current treatments are frequently ineffective and costly, and have several adverse effects. Natural substances have been extensively researched for their anti-MM capabilities. Chemoprevention and adjuvant therapy with natural products is an emerging strategy to prevent, cure or treat melanoma. Numerous prospective drugs are found in aquatic species, providing a plentiful supply of lead cytotoxic chemicals for cancer treatment. Anticancer peptides are less harmful to healthy cells and cure cancer through several different methods, such as altered cell viability, apoptosis, angiogenesis/metastasis suppression, microtubule balance disturbances and targeting lipid composition of the cancer cell membrane. This review addresses marine peptides as effective and safe treatments for MM and details their molecular mechanisms of action.

Therapeutic targeting of anoikis resistance in cutaneous melanoma metastasis

The acquisition of resistance to anoikis, the cell death induced by loss of adhesion to the extracellular matrix, is an absolute requirement for the survival of disseminating and circulating tumour cells (CTCs), and for the seeding of metastatic lesions. In melanoma, a range of intracellular signalling cascades have been identified as potential drivers of anoikis resistance, however a full understanding of the process is yet to be attained. Mechanisms of anoikis resistance pose an attractive target for the therapeutic treatment of disseminating and circulating melanoma cells. This review explores the range of small molecule, peptide and antibody inhibitors targeting molecules involved in anoikis resistance in melanoma, and may be repurposed to prevent metastatic melanoma prior to its initiation, potentially improving the prognosis for patients.

BCL-xL inhibition potentiates cancer therapies by redirecting the outcome of p53 activation from senescence to apoptosis

Cancer therapies trigger diverse cellular responses, ranging from apoptotic death to acquisition of persistent therapy-refractory states such as senescence. Tipping the balance toward apoptosis could improve treatment outcomes regardless of therapeutic agent or malignancy. We find that inhibition of the mitochondrial protein BCL-xL increases the propensity of cancer cells to die after treatment with a broad array of oncology drugs, including mitotic inhibitors and chemotherapy. Functional precision oncology and omics analyses suggest that BCL-xL inhibition redirects the outcome of p53 transcriptional response from senescence to apoptosis, which likely occurs via caspase-dependent down-modulation of p21 and downstream cytostatic proteins. Consequently, addition of a BCL-2/xL inhibitor strongly improves melanoma response to the senescence-inducing drug targeting mitotic kinase Aurora kinase A (AURKA) in mice and patient-derived organoids. This study shows a crosstalk between the mitochondrial apoptotic pathway and cell cycle regulation that can be targeted to augment therapeutic efficacy in cancers with wild-type p53.

Anti-cancer properties of Caulerpa racemosa by altering expression of Bcl-2, BAX, cleaved caspase 3 and apoptosis in HeLa cancer cell culture

The main cause of cervical cancer is infection with Human Papilloma Virus (HPV). Loss of apoptotic control allows cancer cells to survive longer and allows time for mutation accumulation thereby increasing the ability to invade during tumor development. Treatment options for cervical cancer today are surgery, radiotherapy, and chemotherapy. Toxicity to normal cells, adverse side effects, and drug resistance are the main barriers to the use of chemotherapy. Among marine organisms such as bacteria, fungi, actinobacteria, and seaweed have been used for the treatment of cancer. Caulerpa has bioactive metabolites, namely alkaloids, terpenoids, flavonoids, steroids and tannins and its bioactivity has been reported against many diseases including cancer. This study aimed to evaluate the anticancer activity of C. racemosa on HeLa cervical cancer cells. The study used a true experimental post-test only control group design to determine the effect of C. racemosa extract on HeLa cancer cells. C. racemosa extract was given in doses of 50 μg/mL, 100 μg/mL, 200 μg/mL, and 0 μg/mL as controls. Quantitative measurement of apoptosis was measured using flowcytometry and the expression of Bcl-2, BAX, and cleaved-caspase 3 as pro and anti-apoptotic proteins was measured using immunofluorescence. Trypan blue exclusion test was performed to measure cell viability. C. racemosa extract significantly increased the expression of pro-apoptotic proteins BAX and cleaved caspase-3 compared to controls. Annexin V-PI analysis showed the induction of apoptosis in treated cells and decreased HeLa cell viability at 24 hours and 48 hours post-treatment (p-value <0.05). C. racemosa extract has potential as an anti-cancer with pro-apoptotic and anti-proliferative activity on HeLa cancer cells and can be explored further as a cervical cancer therapy.

Pharmacological properties of indirubin and its derivatives

BACKGROUND

Indirubin is the main bioactive component of the traditional Chinese medicine Indigo naturalis and is a bisindole alkaloid. Multiple studies have shown that indirubin exhibits good anticancer, anti-inflammatory and neuroprotective properties.

METHODS

The purpose of this review is to provide a summary of the pharmacological mechanisms of indirubin and its derivatives.

RESULTS

Indirubin and its derivatives exert anticancer effects by regulating the expression of cyclin-dependent kinases (CDKs), GSK-3β, Bax, Bcl-2, C-MYC, matrix metalloproteinases (MMPs), and focal adhesion kinase (FAK) through the PI3K/AKT/mTOR, nuclear factor (NF)-κB, mitogen-activated protein kinase (MAPK), JAK/signal transducer and activator of transcription 3 (STAT3) pathways and other signaling pathways. We also reviewed the anti-inflammatory and neuroprotective properties of indirubin and its derivatives.

CONCLUSION

The findings of recent studies assessing indirubin and its derivatives suggest that these compounds can be used as potential drugs to treat tumors, inflammation, neuropathy and bacterial infection.

Assessment of Betulinic Acid Cytotoxicity and Mitochondrial Metabolism Impairment in a Human Melanoma Cell Line

Melanoma represents one of the most aggressive and drug resistant skin cancers with poor prognosis in its advanced stages. Despite the increasing number of targeted therapies, novel approaches are needed to counteract both therapeutic resistance and the side effects of classic therapy. Betulinic acid (BA) is a bioactive phytocompound that has been reported to induce apoptosis in several types of cancers including melanomas; however, its effects on mitochondrial bioenergetics are less investigated. The present study performed in A375 human melanoma cells was aimed to characterize the effects of BA on mitochondrial bioenergetics and cellular behavior. BA demonstrated a dose-dependent inhibitory effect in both mitochondrial respiration and glycolysis in A375 melanoma cells and at sub-toxic concentrations (10 μM) induced mitochondrial dysfunction by eliciting a decrease in the mitochondrial membrane potential and changes in mitochondria morphology and localization. In addition, BA triggered a dose-dependent cytotoxic effect characterized by apoptotic features: morphological alterations (nuclear fragmentation, apoptotic bodies) and the upregulation of pro-apoptotic markers mRNA expression (Bax, Bad and Bak). BA represents a viable therapeutic option via a complex modulatory effect on mitochondrial metabolism that might be useful in advanced melanoma or as reliable strategy to counteract resistance to standard therapy.

BAX and SMAC regulate bistable properties of the apoptotic caspase system

The initiation of apoptosis is a core mechanism in cellular biology by which organisms control the removal of damaged or unnecessary cells. The irreversible activation of caspases is essential for apoptosis, and mathematical models have demonstrated that the process is tightly regulated by positive feedback and a bistable switch. BAX and SMAC are often dysregulated in diseases such as cancer or neurodegeneration and are two key regulators that interact with the caspase system generating the apoptotic switch. Here we present a mathematical model of how BAX and SMAC control the apoptotic switch. Formulated as a system of ordinary differential equations, the model summarises experimental and computational evidence from the literature and incorporates the biochemical mechanisms of how BAX and SMAC interact with the components of the caspase system. Using simulations and bifurcation analysis, we find that both BAX and SMAC regulate the time-delay and activation threshold of the apoptotic switch. Interestingly, the model predicted that BAX (not SMAC) controls the amplitude of the apoptotic switch. Cell culture experiments using siRNA mediated BAX and SMAC knockdowns validated this model prediction. We further validated the model using data of the NCI-60 cell line panel using BAX protein expression as a cell-line specific parameter and show that model simulations correlated with the cellular response to DNA damaging drugs and established a defined threshold for caspase activation that could distinguish between sensitive and resistant melanoma cells. In summary, we present an experimentally validated dynamic model that summarises our current knowledge of how BAX and SMAC regulate the bistable properties of irreversible caspase activation during apoptosis.

Reduced graphene oxide, but not carbon nanotubes, slows murine melanoma after thermal ablation using LED light in B16F10 lineage cells

Photodynamic therapy is a minimally invasive health technology used to treat cancer and other non-malignant diseases, as well as inactivation of viruses, bacteria and fungi. In this work, we sought to combine the phototherapy technique using low intensity LED (660 nm) to induce ablation in melanoma tumor in mice treated with nanoparticles. In vitro and in vivo studies were conducted, and our results demonstrated that multi-walled carbon nanotubes (MWCNTs) do not destroy tumor cells in vivo, but stimulate the inflammatory process and angiogenesis. Reduced graphene oxide (rGO), has been shown to play a protective role associated with the LED ablation, inducing necrosis, stimulation of immune response by lymphoproliferation, and decreased tumor mass in vivo. We consider that LED alone can be very effective in controlling the growth of melanoma tumors and its association with rGO is potentiated.

Melanoma in the liver: Oxidative stress and the mechanisms of metastatic cell survival

Metastatic melanoma is a fatal disease with a rapid systemic dissemination. The most frequent target sites are the liver, bone, and brain. Melanoma metastases represent a heterogeneous cell population, which associates with genomic instability and resistance to therapy. Interaction of melanoma cells with the hepatic sinusoidal endothelium initiates a signaling cascade involving cytokines, growth factors, bioactive lipids, and reactive oxygen and nitrogen species produced by the cancer cell, the endothelium, and also by different immune cells. Endothelial cell-derived NO and H₂O₂ and the action of immune cells cause the death of most melanoma cells that reach the hepatic microvascularization. Surviving melanoma cells attached to the endothelium of pre-capillary arterioles or sinusoids may follow two mechanisms of extravasation: a) migration through vessel fenestrae or b) intravascular proliferation followed by vessel rupture and microinflammation. Invading melanoma cells first form micrometastases within the normal lobular hepatic architecture via a mechanism regulated by cross-talk with the stroma and multiple microenvironment-related molecular signals. In this review special emphasis is placed on neuroendocrine (systemic) mechanisms as potential promoters of liver metastatic growth. Growing metastatic cells undergo functional and metabolic changes that increase their capacity to withstand oxidative/nitrosative stress, which favors their survival. This adaptive process also involves upregulation of Bcl-2-related antideath mechanisms, which seems to lead to the generation of more resistant cell subclones.

Inhibition of BCL2 Family Members Increases the Efficacy of Copper Chelation in BRAFV600E-Driven Melanoma

The principal unmet need in BRAF^V600E-positive melanoma is lack of an adequate therapeutic strategy capable of overcoming resistance to clinically approved targeted therapies against oncogenic BRAF and/or the downstream MEK1/2 kinases. We previously discovered that copper (Cu) is required for MEK1 and MEK2 activity through a direct Cu-MEK1/2 interaction. Repurposing the clinical Cu chelator tetrathiomolybdate (TTM) is supported by efficacy in BRAF^V600E-driven melanoma models, due in part to inhibition of MEK1/2 kinase activity. However, the antineoplastic activity of Cu chelators is cytostatic. Here, we performed high-throughput small-molecule screens to identify bioactive compounds that synergize with TTM in BRAF^V600E-driven melanoma cells. Genetic perturbation or pharmacologic inhibition of specific members of the BCL2 family of antiapoptotic proteins (BCL-W, BCL-XL, and MCL1) selectively reduced cell viability when combined with a Cu chelator and induced CASPASE-dependent cell death. Further, in BRAF^V600E-positive melanoma cells evolved to be resistant to BRAF and/or MEK1/2 inhibitors, combined treatment with TTM and the clinically evaluated BCL2 inhibitor, ABT-263, restored tumor growth suppression and induced apoptosis. These findings further support Cu chelation as a therapeutic strategy to target oncogene-dependent tumor cell growth and survival by enhancing Cu chelator efficacy with chemical inducers of apoptosis, especially in the context of refractory or relapsed BRAF^V600E-driven melanoma. SIGNIFICANCE: This study unveils a novel collateral drug sensitivity elicited by combining copper chelators and BH3 mimetics for treatment of BRAF^V600E mutation-positive melanoma.

SIRT1 Protects Against Apoptosis by Promoting Autophagy in the Oxygen Glucose Deprivation/Reperfusion-Induced Injury

Silent information regulator 1 (SIRT1) contributes to cellular regulation. Previous studies have reported SIRT1 to be abnormally expressed in the ischemic penumbra of cerebral ischemia/reperfusion (I/R) injury rat model. We investigated the effect of SIRT1 on oxygen and glucose deprivation/reperfusion (OGD/R) cell injury. Over-expressed or silenced SIRT1 pheochromocytoma 12 (PC12) cells were exposed to an in-vitro OGD/R injury. Western blot, TUNEL staining and immunofluorescence analyses were performed to assess apoptosis and autophagy. We found autophagy and apoptosis to be up-regulated and down-regulated, respectively, following the over-expression of SIRT1 in the OGD/R-induced PC12 cells. We also found the silencing of SIRT1 to culminate in the down-regulation and up-regulation of autophagy and apoptosis, respectively. On the basis of our results, we surmise that SIRT1 can promote autophagy and inhibit apoptosis in-vitro, and thus exhibit potential neuroprotection against OGD/R-induced injury. This could facilitate in the development of therapeutic approaches for cerebral I/R injury.

Conjunctival Melanoma: Genetic and Epigenetic Insights of a Distinct Type of Melanoma

Conjunctival melanoma (CjM) is a rare, primary cancer of the ocular region. Genetic and epigenetic characteristics of conjunctival melanoma have not been completely elucidated yet. Conjunctival melanoma presents similarities with cutaneous melanoma, with substantial differences in the biological behavior. We reviewed the genetic and epigenetic insights of CjM involved in invasion and metastatic spread. CjM is commonly characterized by mutations of v-raf murine sarcoma viral oncogene homolog B1 (BRAF), neurofibromin 1 (NF1) and telomerase reverse transcriptase (TERT), high expression of mammalian target of rapamycin (mTOR) and heat shock protein 90 (HSP90), frequent phosphatase and tensin homolog (PTEN) loss and upregulation of specific miRNAs. These features should identify CjM as a distinct subset of melanoma with its own profile, which is more similar to cutaneous melanoma than mucosal melanoma and remarkably different from uveal melanoma.

Systems biology-based investigation of cooperating microRNAs as monotherapy or adjuvant therapy in cancer

MicroRNAs (miRNAs) are short, noncoding RNAs that regulate gene expression by suppressing mRNA translation and reducing mRNA stability. A miRNA can potentially bind many mRNAs, thereby affecting the expression of oncogenes and tumor suppressor genes as well as the activity of whole pathways. The promise of miRNA therapeutics in cancer is to harness this evolutionarily conserved mechanism for the coordinated regulation of gene expression, and thus restoring a normal cell phenotype. However, the promiscuous binding of miRNAs can provoke unwanted off-target effects, which are usually caused by high-dose single-miRNA treatments. Thus, it is desirable to develop miRNA therapeutics with increased specificity and efficacy. To achieve that, we propose the concept of miRNA cooperativity in order to exert synergistic repression on target genes, thus lowering the required total amount of miRNAs. We first review miRNA therapies in clinical application. Next, we summarize the knowledge on the molecular mechanism and biological function of miRNA cooperativity and discuss its application in cancer therapies. We then propose and discuss a systems biology approach to investigate miRNA cooperativity for the clinical setting. Altogether, we point out the potential of miRNA cooperativity to reduce off-target effects and to complement conventional, targeted, or immune-based therapies for cancer.

Interactions between BIM Protein and Beta-Amyloid May Reveal a Crucial Missing Link between Alzheimer's Disease and Neuronal Cell Death

Extensive neuronal cell death is among the pathological hallmarks of Alzheimer's disease. While neuron death is coincident with formation of plaques comprising the beta-amyloid (Aβ) peptide, a direct causative link between Aβ (or other Alzheimer's-associated proteins) and cell toxicity is yet to be found. Here we show that BIM-BH3, the primary proapoptotic domain of BIM, a key protein in varied apoptotic cascades of which elevated levels have been found in brain cells of patients afflicted with Alzheimer's disease, interacts with the 42-residue amyloid isoform Aβ42. Remarkably, BIM-BH3 modulated the structure, fibrillation pathway, aggregate morphology, and membrane interactions of Aβ42. In particular, BIM-BH3 inhibited Aβ42 fibril-formation, while it simultaneously enhanced protofibril assembly. Furthermore, we discovered that BIM-BH3/Aβ42 interactions induced cell death in a human neuroblastoma cell model. Overall, our data provide a crucial mechanistic link accounting for neuronal cell death in Alzheimer's disease patients and the participation of both BIM and Aβ42 in the neurotoxicity process.

Mitochondrial transplantation regulates antitumour activity, chemoresistance and mitochondrial dynamics in breast cancer

Background

The transfer of whole mitochondria that occurs during cell contact has been found to support cancer progression. However, the regulatory role of mitochondria alone is difficult to elucidate due to the complex microenvironment. Currently, mitochondrial transplantation is an available approach for restoring mitochondrial function in mitochondrial diseases but remains unclear in breast cancer. Herein, effects of mitochondrial transplantation via different approaches in breast cancer were investigated.

Methods

Whole mitochondria (approximately 10.5 μg/ml) were transported into MCF-7 breast cancer cells via passive uptake or Pep-1-mediated delivery. Fresh mitochondria isolated from homeoplasmic 143B osteosarcoma cybrids containing mitochondrial DNA (mtDNA) derived from health individuals (Mito) or mtDNA with the A8344G mutation (Mito⁸³⁴⁴) were conjugated with cell-penetrating peptide Pep-1 (P-Mito) or not conjugated prior to cell co-culture. Before isolation, mitochondria were stained with MitoTracker dye as the tracking label. After 3 days of treatment, cell viability, proliferation, oxidative stress, drug sensitivity to Doxorubicin/Paclitaxel and mitochondrial function were assessed.

Results

Compared with P-Mito, a small portion of Mito adhered to the cell membrane, and this was accompanied by a slightly lower fluorescent signal by foreign mitochondria in MCF-7 cells. Both transplantations induced cell apoptosis by increasing the nuclear translocation of apoptosis-inducing factor; inhibited cell growth and decreased oxidative stress in MCF-7 cells; and increased the cellular susceptibility of both the MCF-7 and MDA-MB-231 cell lines to Doxorubicin and Paclitaxel. Mitochondrial transplantation also consistently decreased Drp-1, which resulted in an enhancement of the tubular mitochondrial network, but a distinct machinery through the increase of parkin and mitochondrial fusion proteins was observed in the Mito and P-Mito groups, respectively. Furthermore, although there were no differences in energy metabolism after transplantation of normal mitochondria, metabolism was switched to the energetic and glycolytic phenotypes when the mitochondria were replaced with dysfunctional mitochondria, namely, Mito⁸³⁴⁴ and P-Mito⁸³⁴⁴, due to dramatically induced glycolysis and reduced mitochondrial respiration, respectively. Consequently, transplant-induced growth inhibition was abolished, and cell growth in the Mito⁸³⁴⁴ group was even higher than that in the control group.

Conclusion

This study reveals the antitumour potential of mitochondrial transplantation in breast cancer via distinct regulation of mitochondrial function.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1028-z) contains supplementary material, which is available to authorized users.

Bayesian Hierarchical Varying-sparsity Regression Models with Application to Cancer Proteogenomics

Identifying patient-specific prognostic biomarkers is of critical importance in developing personalized treatment for clinically and molecularly heterogeneous diseases such as cancer. In this article, we propose a novel regression framework, Bayesian hierarchical varying-sparsity regression (BEHAVIOR) models to select clinically relevant disease markers by integrating proteogenomic (proteomic+genomic) and clinical data. Our methods allow flexible modeling of protein-gene relationships as well as induces sparsity in both protein-gene and protein-survival relationships, to select ge-nomically driven prognostic protein markers at the patient-level. Simulation studies demonstrate the superior performance of BEHAVIOR against competing method in terms of both protein marker selection and survival prediction. We apply BEHAV-IOR to The Cancer Genome Atlas (TCGA) proteogenomic pan-cancer data and find several interesting prognostic proteins and pathways that are shared across multiple cancers and some that exclusively pertain to specific cancers.

Spontaneously hypertensive rats are sensitive to thoracic aorta damage induced by a hot and humid environment

The purpose of this study was to investigate the effect of a hot and humid environment on thoracic aorta damage in spontaneously hypertensive rats (SHRs). Wistar-Kyoto (WKY) rats were randomly divided into three groups (n=8 in each group): Control group (WKY-CN), heat exposure for 8 h group (WKY-8) and heat exposure for 24 h group (WKY-24). The CN group was exposed to room temperature (24°C); WKY-8 and WKY-24 group were exposed to heat (32°C) and 65% relative humidity for 8 and 24 h, respectively. Accordingly, SHRs were randomly divided into three groups (n=8 each group): SHR-CN, SHR-8 and SHR-24. After 7 days of heat exposure, the weight, food consumption and blood pressure of rats was measured. Noradrenaline (NA)-induced contraction of aorta rings was measured using an organ bath system, and vascular morphology was observed. Expression levels of apoptotic genes and proteins in the thoracic aorta were also measured. The experimental results indicated that, in the heat exposure environment, rat food intake was reduced. Rat weight was significantly increased in all groups except SHR-24 (all P<0.01 except SHR-8, P<0.05). Heat exposure significantly increased the blood pressure of rats in the WKY-24 (P<0.01 for systolic; P<0.05 for diastolic), SHR-8 and SHR-24 (all P<0.01) groups. This effect was more notable in SHR compared with WKY. NA-induced contraction of aorta rings significantly increased in the SHR-CN group, compared with the WKY-CN group (P<0.01). Heat exposure significantly elevated the NA-induced contraction in both 8 h groups compared with the CN groups (P<0.01). This effect was accompanied by structural damage to the thoracic aorta and increased expression of apoptotic genes and proteins. In conclusion, thoracic aorta damages in SHRs were more sensitive to heat exposure. The enhanced NA-induced contraction may have partly been due to increased apoptosis in the thoracic aorta.

Efficient ferrocifen anticancer drug and Bcl-2 gene therapy using lipid nanocapsules on human melanoma xenograft in mouse

Metastatic melanoma has been described as a highly aggressive cancer with low sensibility to chemotherapeutic agents. New types of drug, such as metal-based drugs (ferrocifens) have emerged and could represent an alternative for melanoma treatment since they show interesting anticancer potential. Furthermore, molecular analysis has evidenced the role of apoptosis in the low sensibility of melanomas and especially of the key regulator, Bcl-2. The objective of this study was to combine two strategies in the same lipid nanocapsules (LNCs): i) gene therapy to modulate anti-apoptotic proteins by the use of Bcl-2 siRNA, and ii) ferrocifens as a new type of anticancer agent. The efficient gene silencing with LNCs was verified by the specific extinction of Bcl-2 in melanoma cells. The cellular toxicity of ferrocifens (ferrociphenol (FcDiOH) or Ansa-FcDiOH) was demonstrated, showing higher efficacy than dacarbazine. Interestingly, the association of siBcl-2 LNCs with Ansa-FcDiOH demonstrated a significant effect on melanoma cell viability. Moreover, the co-encapsulation of siRNA and ferrocifens was successfully performed into LNCs for animal experiments. A reduction of tumor volume and mass was proved after siBcl-2 LNC treatment and Ansa-FcDiOH LNC treatment, individually (around 25%). Finally, the association of both components into the same LNCs increased the reduction of tumor volume to about 50% compared to the control group. In conclusion, LNCs appeared to provide a promising tool for the co-encapsulation of a metal-based drug and siRNA.

Mitochondrial dynamics as regulators of cancer biology

Mitochondria are dynamic organelles that supply energy required to drive key cellular processes, such as survival, proliferation, and migration. Critical to all of these processes are changes in mitochondrial architecture, a mechanical mechanism encompassing both fusion and fragmentation (fission) of the mitochondrial network. Changes to mitochondrial shape, size, and localization occur in a regulated manner to maintain energy and metabolic homeostasis, while deregulation of mitochondrial dynamics is associated with the onset of metabolic dysfunction and disease. In cancers, oncogenic signals that drive excessive proliferation, increase intracellular stress, and limit nutrient supply are all able to alter the bioenergetic and biosynthetic requirements of cancer cells. Consequently, mitochondrial function and shape rapidly adapt to these hostile conditions to support cancer cell proliferation and evade activation of cell death programs. In this review, we will discuss the molecular mechanisms governing mitochondrial dynamics and integrate recent insights into how changes in mitochondrial shape affect cellular migration, differentiation, apoptosis, and opportunities for the development of novel targeted cancer therapies.

Prognostic Significance of Apoptosis-related Markers in Patients With Soft-Tissue Sarcomas of Extremities

Bcl-2 and Bax proteins are key regulators of apoptosis, a process that is deregulated in many human diseases, particularly cancer. Overexpression of antiapoptotic Bcl-2 protein is associated with drug resistance and poor clinical outcome in cancer patients, whereas the expression of proapoptotic Bax protein, commonly detected in soft-tissue sarcoma (STS), is often associated with chemiosensitivity in different tumors. Studies on the clinical implications of apoptosis-related markers Bcl-2 and Bax in STS are limited. In this study, immunohistochemistry for Bcl-2 and Bax was performed on tissue microarrays of 86 multiple types of adult STS of the extremities. Bcl-2 and Bax positive expression was detected in 25.9% and 66.7% of the sarcomas, respectively. Overexpression of both, Bcl-2 and Bax, was directly associated with histologic grade and clinical stage. A significant association between Bax and Bcl-2 expression was also observed (P=0.007). The 5-year overall survival for the group was 57%, and it was lower for cases that overexpressed Bcl-2 (47.6% vs. 58.3%) and Bax (50% vs. 66.7%), although not statistically significant. After multivariate analysis, only the high histologic grade appeared as an independent prognostic factor for the patients (P=0.043; HR=8.0; 95% CI, 1.1-60.1). In our study, Bcl-2 and Bax expression was significantly associated with histologic grade and clinical stage, which are classic factors of poor prognosis. We suggest the use of these proteins as potential prognostic markers in STS of extremities.

BH3-only protein Bim predicts advanced stage of cutaneous melanoma

BACKGROUND

Bim having strong pro-apoptotic effects belongs to the BH3-only proteins of the Bcl-2 protein family and contributes to survival pathways in cancer cells.

OBJECTIVES

We aimed to investigate Bim protein expression in cutaneous melanoma (CM).

METHODS

Bim protein expression was assessed by immunohistochemistry in primary and metastatic melanomas and correlated with clinical and histopathological features.

RESULTS

The Bim immunoreactivity score of the primary melanomas investigated (4.6 ± 1.5) was significantly (P < 0.0001) higher than that observed in metastases (2.8 ± 1.1). Low Bim expression was significantly associated with primary nodular melanoma type (P = 0.005). Moreover, Bim expression was significantly inversely correlated with tumour thickness (r = -0.36; P = 0.0035), advanced stage of disease (stage III and IV; r = -0.60; P < 0.0001), disease relapse (r = -0.18; P = 0.034) and disease-related death (r = -0.19; P = 0.026). Advanced stage of disease was independently predicted by low Bim expression (P = 0.0010, odds ratio: 0.22, 95% CI: 0.10-0.56) on multivariate analysis; however, Bim was not shown to be an independent predictor for disease relapse (P = 0.40) and disease-related death (P = 0.77).

CONCLUSIONS

Our data demonstrate that Bim protein expression is significantly inversely correlated with melanoma features that are associated with worse prognosis. We have shown that Bim protein expression in CM is an independent predictor for advanced disease confirming that this pro-apoptotic BH3-only protein might be a potent biomarker and promising therapeutic target.

Leishmania donovani-Induced Increase in Macrophage Bcl-2 Favors Parasite Survival

Members of the Bcl-2 family are major regulators of apoptosis in mammalian cells, and hence infection-induced perturbations in their expression could result into elimination of the parasites or creation of a niche favoring survival. In this investigation, we uncover a novel role of host Bcl-2 in sustaining Leishmania donovani infection. A rapid twofold increase in Bcl-2 expression occurred in response to parasite challenge. Downregulation of post infection Bcl-2 increase using siRNA or functional inhibition using Bcl-2 small molecule inhibitors interfered with intracellular parasite survival confirming the necessity of elevated Bcl-2 during infection. An increased nitric oxide (NO) response and reduced parasitic burden was observed upon Bcl-2 inhibition, where restitution of the NO response accounted for parasite mortality. Mechanistic insights revealed a major role of elevated Th₂ cytokine IL-13 in parasite-induced Bcl-2 expression via the transcription factor STAT-3, where blocking at the level of IL-13 receptor or downstream kinase JAK-2 dampened Bcl-2 induction. Increase in Bcl-2 was orchestrated through Toll like receptor (TLR)-2-MEK-ERK signaling, and changes in TLR-2 levels affected parasite uptake. In a mouse model of visceral leishmaniasis (VL), Bcl-2 inhibitors partially restored the antimicrobial NO response by at least a twofold increase that resulted in significantly reduced parasite burden. Interestingly, monocytes derived from the peripheral blood of six out of nine human VL subjects demonstrated Bcl-2 expression at significantly higher levels, and sera from these patients showed only marginally quantifiable nitrites. Collectively, our study for the first time reveals a pro-parasitic role of host Bcl-2 and the capacity of host-derived IL-13 to modulate NO levels during infection via Bcl-2. Here, we propose Bcl-2 inhibition as a possible therapeutic intervention for VL.

BET and BRAF inhibitors act synergistically against BRAF-mutant melanoma

Despite major advances in the treatment of metastatic melanoma, treatment failure is still inevitable in most cases. Manipulation of key epigenetic regulators, including inhibition of Bromodomain and extra‐terminal domain (BET) family members impairs cell proliferation in vitro and tumor growth in vivo in different cancers, including melanoma. Here, we investigated the effect of combining the BET inhibitor JQ1 with the BRAF inhibitor Vemurafenib in in vitro and in vivo models of BRAF‐mutant melanoma. We performed cytotoxicity and apoptosis assays, and a xenograft mouse model to determine the in vitro and in vivo efficacy of JQ1 in combination with Vemurafenib against BRAF‐mutant melanoma cell lines. Further, to investigate the molecular mechanisms underlying the effects of combined treatment, we conducted antibody arrays of in vitro drug‐treated cell lines and RNA sequencing of drug‐treated xenograft tumors. The combination of JQ1 and Vemurafenib acted synergistically in BRAF‐mutant cell lines, resulting in marked apoptosis in vitro, with upregulation of proapoptotic proteins. In vivo, combination treatment suppressed tumor growth and significantly improved survival compared to either drug alone. RNA sequencing of tumor tissues revealed almost four thousand genes that were uniquely modulated by the combination, with several anti‐apoptotic genes significantly down‐regulated. Collectively, our data provide a rationale for combined BET and BRAF inhibition as a novel strategy for the treatment of melanoma.

Anti-apoptotic BCL-2 proteins govern cellular outcome following B-RAF(V600E) inhibition and can be targeted to reduce resistance

In theory, pharmacological inhibition of oncogenic signaling is an effective strategy to halt cellular proliferation, induce apoptosis and eliminate cancer cells. In practice, drugs (for example, PLX-4032) that inhibit oncogenes like B-RAFV600E provide relatively short-term success in patients, owing to a combination of incomplete cellular responses and the development of resistance. To define the relationship between PLX-4032-induced responses and resistance, we interrogated the contributions of anti-apoptotic BCL-2 proteins in determining the fate of B-RAFV600E-inhibited melanoma cells. Although PLX-4032 eliminated B-RAFV600E signaling leading to marked cell cycle arrest, only a fraction of cells eventually underwent apoptosis. These data proposed two hypotheses regarding B-RAFV600E inhibition: (1) only a few cells generate a pro-apoptotic signal, or (2) all the cells generate a pro-apoptotic signal but the majority silences this pathway to ensure survival. Indeed, the latter hypothesis is supported by our observations as the addition of ABT-737, an inhibitor to anti-apoptotic BCL-2 proteins, revealed massive apoptosis following PLX-4032 exposure. B-RAFV600E inhibition alone sensitized cells to the mitochondrial pathway of apoptosis characterized by the rapid accumulation of BIM on the outer mitochondrial membrane, which could be functionally revealed by ABT-737 to promote apoptosis and loss of clonogenic survival. Furthermore, PLX-4032-resistant cells demonstrated collateral resistance to conventional chemotherapy, yet could be re-sensitized to PLX-4032 by BCL-2 family inhibition in vivo and conventional chemotherapies in vitro. Our data suggest that inhibiting anti-apoptotic BCL-2 proteins will enhance primary responses to PLX-4032, along with reducing the development of resistance to both targeted and conventional therapies.

Long-term expression pattern of melanocyte markers in light- and dark-pigmented dermo-epidermal cultured human skin substitutes

PURPOSE

Transplantation of pigmented tissue-engineered human autologous skin substitutes represents a promising procedure to cover skin defects. We have already demonstrated that we can restore the patient's native light or dark skin color by adding melanocytes to our dermo-epidermal skin analogs. In this long-term study, we investigated if melanocytes in our skin substitutes continue to express markers as BCL2, SOX9, and MITF, known to be involved in survival, differentiation, and function of melanocytes.

METHODS

Human epidermal melanocytes and keratinocytes, as well as dermal fibroblasts from light- and dark-pigmented skin biopsies were isolated and cultured. Bovine collagen hydrogels containing fibroblasts were prepared, and melanocytes and keratinocytes were seeded in a 1:5 ratio onto the gels. Pigmented dermo-epidermal skin substitutes were transplanted onto full-thickness wounds of immuno-incompetent rats and analyzed for the expression of melanocyte markers after 15 weeks.

RESULTS

Employing immunofluorescence staining techniques, we observed that our light and dark dermo-epidermal skin substitutes expressed the same typical melanocyte markers including BCL2, SOX9, and MITF 15 weeks after transplantation as normal human light and dark skin.

CONCLUSIONS

These data suggest that, even in the long run, our light and dark dermo-epidermal tissue-engineered skin substitutes contain melanocytes that display a characteristic expression pattern as seen in normal pigmented human skin. These findings have crucial clinical implications as such grafts transplanted onto patients should warrant physiological numbers, distribution, and function of melanocytes.

Key regulators of apoptosis execution as biomarker candidates in melanoma

Resistance to apoptosis is frequently detected in malignant melanoma, a skin cancer with rapidly growing incidence rates. Apoptosis resistance may develop with disease progression and may be associated with the poor responsiveness of metastatic melanoma to apoptosis-inducing treatments, such as genotoxic chemotherapy and radiotherapy. Likewise, the efficacy of novel treatment options (targeted kinase inhibitors and immunotherapeutics) that indirectly lead to cell death may depend on the susceptibility of melanoma to apoptosis. At its core, apoptosis execution is regulated by the interplay between a comparatively small number of pro- and anti-apoptotic proteins, and consequently numerous studies have investigated the potential of these players as biomarker candidates. Here, we provide a comprehensive overview of biomarker discovery studies focusing on key regulators of apoptosis execution, critically review the findings of these studies, and outline strategies that address current limitations and challenges in exploiting regulators of apoptosis execution as prognostic or predictive biomarkers in melanoma.

Putting the pieces together: How is the mitochondrial pathway of apoptosis regulated in cancer and chemotherapy?

In order to solve a jigsaw puzzle, one must first have the complete picture to logically connect the pieces. However, in cancer biology, we are still gaining an understanding of all the signaling pathways that promote tumorigenesis and how these pathways can be pharmacologically manipulated by conventional and targeted therapies. Despite not having complete knowledge of the mechanisms that cause cancer, the signaling networks responsible for cancer are becoming clearer, and this information is serving as a solid foundation for the development of rationally designed therapies. One goal of chemotherapy is to induce cancer cell death through the mitochondrial pathway of apoptosis. Within this review, we present the pathways that govern the cellular decision to undergo apoptosis as three distinct, yet connected puzzle pieces: (1) How do oncogene and tumor suppressor pathways regulate apoptosis upstream of mitochondria? (2) How does the B-cell lymphoma 2 (BCL-2) family influence tumorigenesis and chemotherapeutic responses? (3) How is post-mitochondrial outer membrane permeabilization (MOMP) regulation of cell death relevant in cancer? When these pieces are united, it is possible to appreciate how cancer signaling directly impacts upon the fundamental cellular mechanisms of apoptosis and potentially reveals novel pharmacological targets within these pathways that may enhance chemotherapeutic success.

Melanoma genotypes and phenotypes get personal

Traditionally, the diagnosis of metastatic melanoma was terminal to most patients. However, the advancements towards understanding the fundamental etiology, pathophysiology, and treatment have raised melanoma to the forefront of contemporary medicine. Indeed, the evidence of durable remissions are being heard ever more frequently in clinics around the globe. Despite having more gene mutations per cell than any other type of cancer, investigators are overcoming complex genomic landscapes, signaling pathways, and immune checkpoints by generating novel technological methods and clinical protocols with breath-taking speed. Significant progress in deciphering molecular genetics, epigenetics, kinase-driven networks, metabolomics, and immune-enhancing pathways to achieve personalized and positive outcomes has truly provided new hope for melanoma patients. However, obstacles requiring breakthroughs include understanding the influence of sunlight exposure on melanoma etiology, and overcoming all too frequently acquired drug resistance, complicating targeted therapy. Pathologists continue to have critically important roles in advancing the field, particularly in the area of transitioning from microscope-based diagnostic reports to pharmacogenomics through molecularly informed tumor boards. Although melanoma is no longer considered just 'one disease', pathologists will continue this rapidly progressing and exciting journey to identify tumor subtypes, to utilize tumorgraft or so-called patient-derived xenograft (PDX) models, and to develop companion diagnostics to keep pace with the bewildering breakthroughs occurring on a regular basis. Exactly which combination of drugs will ultimately be required to eradicate melanoma cells remains to be determined. However, it is clear that pathologists who are as dedicated to melanoma as the pioneering pathologist Dr Sidney Farber was committed to childhood cancers, will be required as the battle against melanoma continues. In this review, we describe what sets melanoma apart from other tumors, and demonstrate how lessons learned in the melanoma clinic are being transferred to many other types of aggressive neoplasms.

Rapamycin increases pCREB, Bcl-2, and VEGF-A through ERK under normoxia

Rapamycin may serve as a new anti-osteosarcoma (OSA) agent due to its ability to inhibit the metastatic behavior of OSA. However, only limited benefit is observed in rodent studies and clinical trials using rapamycin as a single agent in the treatment of OSA. The target of rapamycin, mammalian target of rapamycin has multiple biological functions and may be linked with the kinases that mediate the phosphorylation of cyclic AMP-responsive element-binding (CREB) protein, an import factor in tumor progression. By employing an OSA cell line MG-63, we investigated how rapamycin regulates the phosphorylation of CREB (pCREB) at Ser133 and the expressions of two putative CREB targets, B-cell lymphoma 2 (Bcl-2) and vascular endothelial growth factor-A (VEGF-A). Under normoxia, we found that rapamycin (100 nM) induced an increase of pCREB that was prevented by mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) inhibitor U0126 or cAMP-dependent protein kinase (PKA) inhibitor H89. However, H89 enhanced Akt phosphorylation and did not decrease the cell viability upon rapamycin treatment. In contrast, U0126 did not enhance Akt phosphorylation and decreased the cell viability upon rapamycin treatment. Moreover, U0126 prevented the rapamycin-induced increase of Bcl-2 and VEGF-A levels. Under hypoxia, rapamycin effectively prevented the hypoxia-induced increase of pCREB, Bcl-2, and VEGF-A. Our study demonstrated that rapamycin might be less effective in treating OSA cells under normoxia and provided the rationale for a combination of rapamycin and MEK/ERK inhibitor in the treatment of OSA.

Apigenin-induced apoptosis in A375 and A549 cells through selective action and dysfunction of mitochondria

We isolated apigenin (5,7,4'-trihydroxy flavone) from ethanolic extract of Lycopodium clavatum (LC) used as a homeopathic mother tincture for treatment of various diseases. We assessed the anticancer potentials of the compound using human malignant melanoma cell line A375 and a lung carcinoma cell line A549 and focussed on its putative molecular mechanism of action on apoptosis induction. We examined the cytotoxicity of apigenin in both cancer cells and normal peripheral blood mononuclear cells (PBMC). A375 cells were more prone to apigenin-induced apoptosis, as compared with A549 cells after 24 h of treatment, while PBMC showed little or no cytotoxicity to apigenin. We also evaluated the effects of apigenin on interaction with DNA by comparative analysis of circular dichroism spectral data and melting temperature profiles (Tm) of calf thymus DNA (CT-DNA) treated with or without apigenin. Reactive oxygen species (ROS) accumulation in mitochondria, super-oxide dismutase and total thiol group (GSH) activities were also analyzed. The apoptotic process involved mitochondrial pathway associated with apigenin-DNA interaction, DNA fragmentation, ROS accumulation, cytochrome c (cyt c) release and mitochondrial transmembrane potential depolarization, Bax, caspase 3, 9, PARP, up-regulation, Bcl-2 down-regulation and down-regulation of cyt c in the mitochondrial fraction. Results of mitochondrial inner membrane swelling measurements, intracellular ADP/ATP ratio and ATPase activity showed that in A549 cells, apigenin did not appear to directly target the mitochondrial oxidative phosphorylation system but rather acted at an upstream step to activate the mitochondrial apoptotic pathway. However, apigenin could directly target and impair mitochondrial function in A375 cells by breaking down their oxidative phosphorylation system. Collectively, these results suggest that apigenin exhibits anticancer potential in A375 and A549 cells that may be mediated through DNA interaction, damage and mitochondrial dysfunction either by direct or indirect action on mitochondrial oxidative phosphorylation system.

Anti-apoptotic proteins on guard of melanoma cell survival

Apoptosis plays a pivotal role in sustaining proper tissue development and homeostasis. Evading apoptosis by cancer cells is a part of their adaption to microenvironment and therapies. Cellular integrity is predominantly maintained by pro-survival members of Bcl-2 family and IAPs. Melanoma cells are characterized by a labile and stage-dependent phenotype. Pro-survival molecules can protect melanoma cells from apoptosis and mediate other processes, thus enhancing aggressive phenotype. The essential role of Bcl-2, Mcl-1, Bcl-X(L), livin, survivin and XIAP was implicated for melanoma, often in a tumor stage-dependent fashion. In this review, the current knowledge of pro-survival machinery in melanoma is discussed.

Irradiated riboflavin diminishes the aggressiveness of melanoma in vitro and in vivo

Melanoma is one of the most aggressive skin cancers due to its high capacity to metastasize. Treatment of metastatic melanomas is challenging for clinicians, as most therapeutic agents have failed to demonstrate improved survival. Thus, new candidates with antimetastatic activity are much needed. Riboavin (RF) is a component of the vitamin B complex and a potent photosensitizer. Previously, our group showed that the RF photoproducts (iRF) have potential as an antitumoral agent. Hence, we investigated the capacity of iRF on modulating melanoma B16F10 cells aggressiveness in vitro and in vivo. iRF decreases B16F10 cells survival by inhibiting mTOR as well as Src kinase. Moreover, melanoma cell migration was disrupted after treatment with iRF, mainly by inhibition of metalloproteinase (MMP) activity and expression, and by increasing TIMP expression. Interestingly, we observed that the Hedgehog (HH) pathway was inhibited by iRF. Two mediators of HH signaling, GLI1 and PTCH, were downregulated, while SUFU expression (an inhibitor of this cascade) was enhanced. Furthermore, inhibition of HH pathway signaling by cyclopamine and Gant 61 potentiated the antiproliferative action of RF. Accordingly, when a HH ligand was applied, the effect of iRF was almost completely abrogated. Our findings indicate that Hedgehog pathway is involved on the modulation of melanoma cell aggressiveness by iRF. Moreover, iRF treatment decreased pulmonary tumor formation in a murine experimental metastasis model. Research to clarify the molecular action of flavins, in vivo, is currently in progress. Taken together, the present data provides evidence that riboflavin photoproducts may provide potential candidates for improving the efficiency of melanoma treatment.

Sensitization to the mitochondrial pathway of apoptosis augments melanoma tumor cell responses to conventional chemotherapeutic regimens

Metastatic malignant melanoma is highly resistant to chemotherapy, and the average survival rate is under 1 year. The only FDA-approved conventional chemotherapy (i.e., dacarbazine) targets melanoma tumor cells by inducing a form of cell death referred to as apoptosis. However, dacarbazine exhibits a response rate of ∼5%, and combination chemotherapies consisting of cisplatin, vinblastine, and dacarbazine often offer little clinical advantage over dacarbazine alone. Apoptosis is governed by the BCL-2 family of proteins, which is comprised of anti-apoptotic and pro-apoptotic members. To determine if the anti-apoptotic BCL-2 repertoire established the cell death threshold and chemoresistance in melanoma, a novel treatment strategy was designed to inhibit the anti-apoptotic BCL-2 members with ABT-737. Using various melanoma model systems, we determined the affects of ABT-737 on sensitivity to dacarbazine-based regimens. Strikingly, ABT-737 re-sensitized melanoma cell lines to common chemotherapeutics leading to marked BIM-mediated apoptosis. Cellular features of the ABT-737 combination treatments were loss of proliferation, mitochondrial fragmentation, nuclear condensation, phosphatidylserine exposure, and decreased clonogenic survival. We also observed significant anti-tumor activity in an in vivo melanoma model system. Our data indicate that ABT-737 may be a beneficial adjuvant therapy to improve melanoma response rates when conventional chemotherapy is the only option.

1,3-Bis(3,5-dichlorophenyl) urea compound 'COH-SR4' inhibits proliferation and activates apoptosis in melanoma

The current clinical interventions in malignant melanomas are met with poor response to therapy due to dynamic regulation of multiple melanoma signaling pathways consequent to administration of single target agents. In this context of limited response to single target agents, novel candidate molecules capable of effectively inducing tumor inhibition along with targeting multiple critical nodes of melanoma signaling assume translational significance. In this regard, we investigated the anti-cancer effects of a novel dichlorophenyl urea compound called COH-SR4 in melanoma. The SR4 treatment decreased the survival and inhibited the clonogenic potential of melanomas along with inducing apoptosis in vitro cultures. SR4 treatments lead to inhibition of GST activity along with causing G2/M phase cell cycle arrest. Oral administration of 4 mg/kg SR4 leads to effective inhibition of tumor burdens in both syngeneic and nude mouse models of melanoma. The SR4 treatment was well tolerated and no overt toxicity was observed. The histopathological examination of resected tumor sections revealed decreased blood vessels, decrease in the levels of angiogenesis marker, CD31, and proliferation marker, Ki67, along with an increase in pAMPK levels. Western blot analyses of resected tumor lysates revealed increased PARP cleavage, Bim, pAMPK along with decreased pAkt, vimentin, fibronectin, CDK4 and cyclin B1. Thus, SR4 represents a novel candidate for the further development of mono and combinatorial therapies to effectively target aggressive and therapeutically refractory melanomas.