Inhibition of activated receptor tyrosine kinases by Sunitinib induces growth arrest and sensitizes melanoma cells to Bortezomib by blocking Akt pathway

Angiogenesis Still Plays a Crucial Role in Human Melanoma Progression

Angiogenesis plays a pivotal role in tumor progression, particularly in melanoma, the deadliest form of skin cancer. This review synthesizes current knowledge on the intricate interplay between angiogenesis and tumor microenvironment (TME) in melanoma progression. Pro-angiogenic factors, including VEGF, PlGF, FGF-2, IL-8, Ang, TGF-β, PDGF, integrins, MMPs, and PAF, modulate angiogenesis and contribute to melanoma metastasis. Additionally, cells within the TME, such as cancer-associated fibroblasts, mast cells, and melanoma-associated macrophages, influence tumor angiogenesis and progression. Anti-angiogenic therapies, while showing promise, face challenges such as drug resistance and tumor-induced activation of alternative angiogenic pathways. Rational combinations of anti-angiogenic agents and immunotherapies are being explored to overcome resistance. Biomarker identification for treatment response remains crucial for personalized therapies. This review highlights the complexity of angiogenesis in melanoma and underscores the need for innovative therapeutic approaches tailored to the dynamic TME.

The role of angiogenesis in melanoma: Clinical treatments and future expectations

The incidence of melanoma has increased rapidly over the past few decades, with mortality accounting for more than 75% of all skin cancers. The high metastatic potential of Melanoma is an essential factor in its high mortality. Vascular angiogenic system has been proved to be crucial for the metastasis of melanoma. An in-depth understanding of angiogenesis will be of great benefit to melanoma treatment and may promote the development of melanoma therapies. This review summarizes the recent advances and challenges of anti-angiogenic agents, including monoclonal antibodies, tyrosine kinase inhibitors, human recombinant Endostatin, and traditional Chinese herbal medicine. We hope to provide a better understanding of the mechanisms, clinical research progress, and future research directions of melanoma.

Sunitinib malate inhibits hemangioma cell growth and migration by suppressing focal adhesion kinase signaling

Sunitinib malate is a small molecule that targets multiple receptor tyrosine kinases and blocks their activity. Receptors targeted by sunitinib are implicated in tumor vascularization and are overexpressed by vascular tumors encountered in infants, namely, hemangiomas. Of note is that there is still no definitive treatment for these commonly occurring tumors of infancy. The purpose of this study was to investigate the effects of sunitinib malate on hemangioma using endothelial cells isolated from a murine model of the neoplasm (sEnd.2). The effects of the drug on cell growth were evaluated using the crystal violet assay and flow cytometry, while the scratch assay was employed to measure cell migration. Proteins associated with cell migration and angiogenesis were detected using western blotting. Sunitinib was investigated further to determine its effects on the production of reactive oxygen species, a parameter associated with the promotion of neovascularization in tumors. The results showed that sunitinib significantly reduced the growth of sEnd.2 cells by causing the cells to accumulate in the sub-G1 phase of the cell cycle, and also induced a significant decrease in the migration of these hemangioma cells (P < 0.05). The western blot assay showed a decrease in the expression of adhesion proteins, focal adhesion kinase and paxillin at IC50 doses, although the expression of cadherin did not change significantly (P < 0.05). In addition, transforming growth factor-β1 (TGF-β1) expression was decreased in sunitinib-treated cells at the same dose. The adhesion proteins as well as TGF-β1 regulate cell movement and have been implicated in tumor progression. Thus, sunitinib malate may have potential in the treatment of hemangiomas.

Peptides, proteins and nanotechnology: a promising synergy for breast cancer targeting and treatment

INTRODUCTION

The use of nanoparticles for breast cancer targeting and treatment has become a reality. They are safe and possess interesting peculiarities such as the unspecific accumulation into the tumor site and the possibility to activate controlled drug release as compared to free drugs. However, there are still many areas of improvement which can certainly be addressed with the use of peptide-based elements.

AREAS COVERED

The article reviews different preclinical strategies employing peptides and proteins in combination with nanoparticles for breast cancer targeting and treatment as well as peptide and protein-targeted encapsulated drugs, and it lists the current clinical status of therapies using peptides and proteins for breast cancer.

EXPERT OPINION

The conjugation of protein and peptides can improve tumor homing of nanoparticles, increase cellular penetration and attack specific drivers and vulnerabilities of the breast cancer cell to promote tumor cytotoxicity while reducing secondary effects in healthy tissues. Examples are the use of antibodies, arginylglycylaspartic acid (RGD) peptides, membrane disruptive peptides, interference peptides, and peptide vaccines. Although their implementation in the clinic has been relatively slow up to now, we anticipate great progress in the field which will translate into more efficacious and selective nanotherapies for breast cancer.

From Seabed to Bedside: A Review on Promising Marine Anticancer Compounds

The marine environment represents an outstanding source of antitumoral compounds and, at the same time, remains highly unexplored. Organisms living in the sea synthesize a wide variety of chemicals used as defense mechanisms. Interestingly, a large number of these compounds exert excellent antitumoral properties and have been developed as promising anticancer drugs that have later been approved or are currently under validation in clinical trials. However, due to the high need for these compounds, new methodologies ensuring its sustainable supply are required. Also, optimization of marine bioactives is an important step for their success in the clinical setting. Such optimization involves chemical modifications to improve their half-life in circulation, potency and tumor selectivity. In this review, we outline the most promising marine bioactives that have been investigated in cancer models and/or tested in patients as anticancer agents. Moreover, we describe the current state of development of anticancer marine compounds and discuss their therapeutic limitations as well as different strategies used to overcome these limitations. The search for new marine antitumoral agents together with novel identification and chemical engineering approaches open the door for novel, more specific and efficient therapeutic agents for cancer treatment.

Sensitizing endometrial cancer to ionizing radiation by multi-tyrosine kinase inhibition

Objective

Endometrial carcinoma is the most frequent gynecological cancer. About 15% of these cancers are of high risk and radiotherapy still remains the most suitable treatment. In this context, agents able to promote radiosensitization are of great interest. Here, we describe for the first time the radiosensitization ability of sunitinib in endometrial carcinoma.

Methods

Four endometrial carcinoma cell lines were used for the study. The activation of apoptosis signalling pathways and tyrosine kinase receptors were analysed by Western blot, luciferase assays and Immunoprecipitation. Radiosensitization effects were assessed using clonogenic assays. p65 and phosphatase and tensin homolog (PTEN) were upregulated by lentiviral transduction.

Results

We discovered that ionizing radiation activates the pro-oncogenic proteins and signalling pathways KIT, protein kinase B (AKT), and nuclear factor kappa B (NF-κB) and these activations were abrogated by sunitinib, resulting in a radiosensitization effect. We found out that AKT pathway is greatly involved in this process as PTEN restoration in the PTEN-deficient cell line RL95-2 is sufficient to inhibit AKT, rendering these cells more susceptible to ionizing radiation and sunitinib-induced radiosensitization. In Ishikawa 3-H-12 cells, radiosensitization effects and inhibition of AKT were achieved by PTEN restoration plus treatment with the phosphoinositide-3-kinase inhibitor LY294002. This suggests that endometrial tumors could have different sensitivity degree to radiotherapy and susceptibility to sunitinib-induced radiosensitization depending on their AKT activation levels.

Conclusions

Our results provide the rationale of using sunitinib as neoadjuvant treatment prior radiotherapy which could be a starting point for the implementation of sunitinib and radiotherapy in the clinic for the treatment of recalcitrant endometrial cancers.

Inhibition of the PI3K/AKT signaling pathway sensitizes diffuse large B-cell lymphoma cells to treatment with proteasome inhibitors via suppression of BAG3

Proteasome inhibitors represent a novel class of drugs that have clinical efficacy against hematological and solid cancer types, including acute myeloid leukaemia, myelodysplastic syndrome an non-small cell lung cancer. It has been demonstrated that the anti-apoptotic protein B-cell lymphoma-2-associated athanogene 3 (BAG3) is induced by proteasome inhibitors in various cancer cells and serves an important role in chemotherapy resistance. The phosphatidylinositol 3-kinase (PI3K)/RAC-α serine/threonine-protein kinase (AKT) pathway is constitutively activated in a number of lymphoid malignancy types, including diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma. In the present study, the aim was to elucidate the role of the PI3K/AKT signaling pathway in the induction of BAG3, following exposure to a proteasome inhibitor in DLBCL cell lines. Bortezomib and MG132 were used as proteasome inhibitors. Western blotting was used to evaluate the roles of proteasome inhibitors and the PI3K/AKT pathway in BAG3 induction in DLBCL cells (LY1 and LY8), and LY294002 was used to block the PI3K/AKT pathway. Cell viability was detected using a Cell Counting Kit-8 assay. Apoptosis of LY1 and LY8 cells was quantified by Annexin V/7-amino-actinomycin D flow cytometry. The BAG3 protein was markedly induced upon exposure to bortezomib and MG132 in a dose-dependent manner. The PI3K/AKT inhibitor LY294002 significantly suppressed the induction of BAG3 by proteasome inhibitors. Inhibition of the PI3K/AKT pathway decreased the proliferation and increased the apoptosis induced by proteasome inhibitors. The present results indicated that the PI3K/AKT pathway is associated with the activation of BAG3 expression in DLBCL cells, and is involved in the protective response against proteasome inhibition.

Autophagy inhibitors chloroquine and LY294002 enhance temozolomide cytotoxicity on cutaneous melanoma cell lines in vitro

Patients with metastatic melanoma are difficult to treat and have a very poor prognosis because of high resistance to therapy. Recent evidence indicates that tumors could overcome death through autophagy, a survival mechanism, which cancer cells use under lack of energy and nutrient deprivation. Melanoma cells have different sensitivity to temozolomide (TMZ) treatment. In this study, we showed that the combination of autophagy inhibitors chloroquine or LY294002 and TMZ induced enhanced cytotoxicity of alkylating agents on human melanoma cell lines. All assays were performed on patient-derived melanoma cell lines. The effectiveness of the combined treatment of TMZ and autophagy inhibitors was determined using an MTT assay. Next, we analyzed the expression mRNA level of Beclin 1, LC3B, and p62/STSQM1 and the relative expression of LC3B protein under combined treatment. Autophagic flux was determined by analysis of colocalization of Lysotracker Red and LC3B puncta. Apoptosis was measured by Annexin V/PI staining. Cell cycle analyses were carried out by flow cytometry. We showed that autophagy inhibition could enhance melanoma cell death combined with TMZ therapy. Chloroquine synergistically enhanced the TMZ-induced growth arrest and increased the G0/G1 population in Mel Z and Mel IL cell lines, but not Mel MTP. The expression analysis showed that autophagy involvement in TMZ enhanced cytotoxicity. Furthermore, LY294002, an early-stage autophagy, and PI3K inhibitor were found to exert similar effects. Both chloroquine and LY294002 improved the cytotoxic effect of TMZ treatment, making this combination applicable as a potent antitumor treatment for metastatic melanoma.

Synthesis of piperazine-based thiazolidinones as VEGFR2 tyrosine kinase inhibitors inducing apoptosis

Aim: VEGFR2 tyrosine kinase is a main target in suppressing cancer growth and metastasis. Materials & methods: Piperazine-based thiazolidinones were synthesized and screened for their anticancer and VEGFR2 tyrosine kinase inhibitory activity. Results: Compounds 11, 13 and 16 displayed potent anticancer activity against HepG-2 with IC50 values 0.03–0.06 μM. They were safe on normal human fibroblasts with selectivity indices 8.09, 11.40 and 4.37, respectively. Also, these compounds showed VEGFR2 tyrosine kinase inhibitory activities more than the reference staurosporine with IC50 values <0.3 μM. Lineweaver–Burk plot revealed that these compounds behaved as uncompetitive VEGFR2 tyrosine kinase inhibitors. They also induced caspase-dependent apoptosis in HepG-2. In addition, these compounds revealed good binding within VEGFR2 tyrosine kinase enzyme in comparison with sorafenib reference. Conclusion: Compounds 11, 13 and 16 comprise a new promising scaffold of selective VEGFR2 tyrosine kinase inhibitors with caspase-dependent apoptotic activities.

Tetraspanin 8 is a novel regulator of ILK-driven β1 integrin adhesion and signaling in invasive melanoma cells

Melanoma is well known for its propensity for lethal metastasis and resistance to most current therapies. Tumor progression and drug resistance depend to a large extent on the interplay between tumor cells and the surrounding matrix. We previously identified Tetraspanin 8 (Tspan8) as a critical mediator of melanoma invasion, whose expression is absent in healthy skin. The present study investigated whether Tspan8 may influence cell-matrix anchorage and regulate downstream molecular pathways leading to an aggressive behavior. Using silencing and ectopic expression strategies, we showed that Tspan8-mediated invasion of melanoma cells resulted from defects in cell-matrix anchorage by interacting with β1 integrins and by interfering with their clustering, without affecting their surface or global expression levels. These effects were associated with impaired phosphorylation of integrin-linked kinase (ILK) and its downstream target Akt-S473, but not FAK. Specific blockade of Akt or ILK activity strongly affected cell-matrix adhesion. Moreover, expression of a dominant-negative form of ILK reduced β₁ integrin clustering and cell-matrix adhesion. Finally, we observed a tumor-promoting effect of Tspan8 in vivo and a mutually exclusive expression pattern between Tspan8 and phosphorylated ILK in melanoma xenografts and human melanocytic lesions. Altogether, the in vitro, in vivo and in situ data highlight a novel regulatory role for Tspan8 in melanoma progression by modulating cell-matrix interactions through β1 integrin-ILK axis and establish Tspan8 as a negative regulator of ILK activity. These findings emphasize the importance of targeting Tspan8 as a means of switching from low- to firm-adhesive states, mandatory to prevent tumor dissemination.

AURKA Overexpression Is Driven by FOXM1 and MAPK/ERK Activation in Melanoma Cells Harboring BRAF or NRAS Mutations: Impact on Melanoma Prognosis and Therapy

The cell cycle-related genes AURKA and FOXM1 are overexpressed in melanoma. We show here that AURKA overexpression is associated with poor prognosis in three independent cohorts of melanoma patients and correlates with the presence of genomic amplification of AURKA locus and BRAF^V600E mutation. AURKA overexpression may also be driven by increased promoter activation through elements such as ETS and FOXM1 found within the 5' proximal promoter region. Activated MAPK/ERK signaling pathway mediates robust AURKA promoter activation, thereby knockdown of BRAF^V600E and ERK inhibition results in reduced AURKA transcription and expression. We show a positive correlation between FOXM1 and AURKA expression in three independent cohorts of melanoma patients. FOXM1 silencing decreases expression of AURKA and late cell cycle genes in melanoma cells. We further found that FOXM1 expression levels are significantly higher in tumors carrying the BRAF^V600E mutation compared with the wild-type BRAF (BRAF^wt). Accordingly, the knockdown of BRAF^V600E also reduces the expression of FOXM1 in BRAF^V600E cells. Moreover, Aurora kinase A and FOXM1 inhibition by either genetic knockdown or pharmacologic inhibitors impair melanoma growth and survival both in culture and in vivo, underscoring their therapeutic value for melanoma patients who fail to benefit from BRAF/MEK signaling inhibition.

Functional exploration of colorectal cancer genomes using Drosophila

The multigenic nature of human tumours presents a fundamental challenge for cancer drug discovery. Here we use Drosophila to generate 32 multigenic models of colon cancer using patient data from The Cancer Genome Atlas. These models recapitulate key features of human cancer, often as emergent properties of multigenic combinations. Multigenic models such as ras p53 pten apc exhibit emergent resistance to a panel of cancer-relevant drugs. Exploring one drug in detail, we identify a mechanism of resistance for the PI3K pathway inhibitor BEZ235. We use this data to identify a combinatorial therapy that circumvents this resistance through a two-step process of emergent pathway dependence and sensitivity we term ‘induced dependence'. This approach is effective in cultured human tumour cells, xenografts and mouse models of colorectal cancer. These data demonstrate how multigenic animal models that reference cancer genomes can provide an effective approach for developing novel targeted therapies.

Colorectal cancers carry multiple mutations. Here, the authors use Drosophila as a model organism and assess multiple combinations of mutations and their response to various drugs, providing further insight into drug resistance mechanisms.

Synergistic suppression of the PI3K inhibitor CAL-101 with bortezomib on mantle cell lymphoma growth

Objective

To investigate the effects of CAL-101, particularly when combined with bortezomib (BTZ) on mantle cell lymphoma (MCL) cells, and to explore its relative mechanisms.

Methods

MTT assay was applied to detect the inhibitory effects of different concentrations of CAL-101. MCL cells were divided into four groups: control group, CAL-101 group, BTZ group, and CAL-101/BTZ group. The expression of PI3K-p110σ, AKT, ERK, p-AKT and p-ERK were detected by Western blot. The apoptosis rates of CAL-101 group, BTZ group, and combination group were detected by flow cytometry. The location changes of nuclear factor kappa-B (NF-κB) of 4 groups was investigated by NF-κB Kit exploring. Western blot was applied to detect the levels of caspase-3 and the phosphorylation of AKT in different groups.

Results

CAL-101 dose- and time-dependently induced reduction in MCL cell viability. CAL-101 combined with BTZ enhanced the reduction in cell viability and apoptosis. Western blot analysis showed that CAL-101 significantly blocked the PI3K/AKT and ERK signaling pathway in MCL cells. The combination therapy contributed to the inactivation of NF-κB and AKT in MCL cell lines. However, cleaved caspase-3 was up-regulated after combined treatment.

Conclusion

Our study showed that PI3K/p110σ is a novel therapeutic target in MCL, and the underlying mechanism could be the blocking of the PI3K/AKT and ERK signaling pathways. These findings provided a basis for clinical evaluation of CAL-101 and a rationale for its application in combination therapy, particularly with BTZ.

Synergistic Antivascular and Antitumor Efficacy with Combined Cediranib and SC6889 in Intracranial Mouse Glioma

Prognosis remains extremely poor for malignant glioma. Targeted therapeutic approaches, including single agent anti-angiogenic and proteasome inhibition strategies, have not resulted in sustained anti-glioma clinical efficacy. We tested the anti-glioma efficacy of the anti-angiogenic receptor tyrosine kinase inhibitor cediranib and the novel proteasome inhibitor SC68896, in combination and as single agents. To assess anti-angiogenic effects and evaluate efficacy we employed 4C8 intracranial mouse glioma and a dual-bolus perfusion MRI approach to measure K^trans, relative cerebral blood flow and volume (rCBF, rCBV), and relative mean transit time (rMTT) in combination with anatomical MRI measurements of tumor growth. While single agent cediranib or SC68896 treatment did not alter tumor growth or survival, combined cediranib/SC68896 significantly delayed tumor growth and increased median survival by 2-fold, compared to untreated. This was accompanied by substantially increased tumor necrosis in the cediranib/SC68896 group (p<0.01), not observed with single agent treatments. Mean vessel density was significantly lower, and mean vessel lumen area was significantly higher, for the combined cediranib/SC68896 group versus untreated. Consistent with our previous findings, cediranib alone did not significantly alter mean tumor rCBF, rCBV, rMTT, or K^trans. In contrast, SC68896 reduced rCBF in comparison to untreated, but without concomitant reductions in rCBV, rMTT, or K^trans. Importantly, combined cediranib/SC68896 substantially reduced rCBF, rCBV. rMTT, and K^trans. A novel analysis of K^trans/rCBV suggests that changes in K^trans with time and/or treatment are related to altered total vascular surface area. The data suggest that combined cediranib/SC68896 induced potent anti-angiogenic effects, resulting in increased vascular efficiency and reduced extravasation, consistent with a process of vascular normalization. The study represents the first demonstration that the combination of cediranib with a proteasome inhibitor substantially increases the anti-angiogenic efficacy produced from either agent alone, and synergistically slows glioma tumor growth and extends survival, suggesting a promising treatment which warrants further investigation.

The 26S proteasome is a multifaceted target for anti-cancer therapies

Proteasomes play a critical role in the fate of proteins that are involved in major cellular processes, including signal transduction, gene expression, cell cycle, replication, differentiation, immune response, cellular response to stress, etc. In contrast to non-specific degradation by lysosomes, proteasomes are highly selective and destroy only the proteins that are covalently labelled with small proteins, called ubiquitins. Importantly, many diseases, including neurodegenerative diseases and cancers, are intimately connected to the activity of proteasomes making them an important pharmacological target. Currently, the vast majority of inhibitors are aimed at blunting the proteolytic activities of proteasomes. However, recent achievements in solving structures of proteasomes at very high resolution provided opportunities to design new classes of small molecules that target other physiologically-important enzymatic activities of proteasomes, including the de-ubiquitinating one. This review attempts to catalog the information available to date about novel classes of proteasome inhibitors that may have important pharmacological ramifications.

PDGFRα up-regulation mediated by sonic hedgehog pathway activation leads to BRAF inhibitor resistance in melanoma cells with BRAF mutation

Control of BRAF(V600E) metastatic melanoma by BRAF inhibitor (BRAF-I) is limited by intrinsic and acquired resistance. Growth factor receptor up-regulation is among the mechanisms underlying BRAF-I resistance of melanoma cells. Here we demonstrate for the first time that PDGFRα up-regulation causes BRAF-I resistance. PDGFRα inhibition by PDGFRα-specific short hairpin (sh)RNA and by PDGFRα inhibitors restores and increases melanoma cells' sensitivity to BRAF-I in vitro and in vivo. This effect reflects the inhibition of ERK and AKT activation which is associated with BRAF-I resistance of melanoma cells. PDGFRα up-regulation is mediated by Sonic Hedgehog Homolog (Shh) pathway activation which is induced by BRAF-I treatment. Similarly to PDGFRα inhibition, Shh inhibition by LDE225 restores and increases melanoma cells' sensitivity to BRAF-I. These effects are mediated by PDGFRα down-regulation and by ERK and AKT inhibition. The clinical relevance of these data is indicated by the association of PDGFRα up-regulation in melanoma matched biopsies of BRAF-I +/- MEK inhibitor treated patients with shorter time to disease progression and less tumor regression. These findings suggest that monitoring patients for early PDGFRα up-regulation will facilitate the identification of those who may benefit from the treatment with BRAF-I in combination with clinically approved PDGFRα or Shh inhibitors.

Matrine inhibits the growth and induces apoptosis of osteosarcoma cells in vitro by inactivating the Akt pathway

Matrine, a natural product, has been demonstrated to be a promising chemotherapeutic drug for some cancers. Using flow cytometric analysis of the cell cycle and apoptosis, we found that matrine inhibited the proliferation and induced apoptosis in the human osteosarcoma (OS) cell lines MG63, HOS, U2OS, and SAOS2 in vitro in a dose-dependent manner. We therefore assessed the role of the serine/threonine kinase Akt in the regulation of matrine-mediated cell growth inhibition and apoptosis induction in human OS cell lines. After treatment for 48 h, matrine induced G0/G1-stage cell cycle arrest in MG63, U2OS, and SAOS2 cells associated with an increase in the expression of p27(Kip1) and a decrease in the expression of Akt, glycogen synthase kinase 3 (GSK3)-β (Ser9), and cyclin D1. Furthermore, the pro-apoptotic factor Bax was upregulated. Overall, our findings suggest that matrine may be an effective anti-osteosarcoma drug due to its ability to inhibit proliferation and induce apoptosis in OS cells, possibly through the involvement of Akt signaling.

Distinct antifibrogenic effects of erlotinib, sunitinib and sorafenib on rat pancreatic stellate cells

AIM: To study if three clinically available small molecule kinase inhibitors (SMI), erlotinib, sunitinib and sorafenib, exert antifibrogenic effects on pancreatic stellate cells (PSC) and analyze the basis of their action.

METHODS: Cultured rat PSC were exposed to SMI. Cell proliferation and viability were assessed employing 5-bromo-2’-deoxyuridine incorporation assay and flow cytometry, respectively. 2-Deoxy-2-[¹⁸F] fluoroglucose (¹⁸F-FDG) uptake was measured to study metabolic activity. Exhibition of the myofibroblastic PSC phenotype was monitored by immunofluorescence analysis of α-smooth muscle actin (α-SMA) expression. Levels of mRNA were determined by real-time PCR, while protein expression and phosphorylation were analyzed by immunoblotting. Transforming growth factor-β1 (TGF-β1) levels in culture supernatants were quantified by ELISA.

RESULTS: All three SMI inhibited cell proliferation and ¹⁸F-FDG uptake in a dose-dependent manner and without significant cytotoxic effects. Furthermore, additive effects of the drugs were observed. Immunoblot analysis showed that sorafenib and sunitib, but not erlotinib, efficiently blocked activation of the AKT pathway, while all three drugs displayed little effect on phosphorylation of ERK1/2. Cells treated with sorafenib or sunitinib expressed less interleukin-6 mRNA as well as less collagen type 1 mRNA and protein. Sorafenib was the only drug that also upregulated the expression of matrix metalloproteinase-2 and reduced the secretion of TGF-β1 protein. All three drugs showed insignificant or discordant effects on the mRNA and protein levels of α-SMA.

CONCLUSION: The tested SMI, especially sorafenib, exert inhibitory effects on activated PSC, which should be further evaluated in preclinical studies.

Towards combinatorial targeted therapy in melanoma: from pre-clinical evidence to clinical application (review)

Over the last few years, clinical trials with BRAF and mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitors have shown significant clinical activity in melanoma, but only a fraction of patients respond to these therapies, and development of resistance is frequent. This has prompted a large set of preclinical studies looking at several new combinatorial approaches of pathway- or target-specific inhibitors. At least five main drug association strategies have been verified in vitro and in preclinical models. The most promising include: i) vertical targeting of either MEK or phosphoinositide-3 kinase (PI3K)/mammalian target of rapamycin (mTOR) pathways, or their combined blockade; ii) association of receptor tyrosine kinases (RTKs) inhibitors with other pro-apoptotic strategies; iii) engagement of death receptors in combination with MEK-, mTOR/PI3K-, histone deacetylase (HDAC)-inhibitors, or with anti-apoptotic molecules modulators; iv) strategies aimed at blocking anti-apoptotic proteins belonging to B-cell lymphoma (Bcl-2) or inhibitors of apoptosis (IAP) families associated with MEK/BRAF/p38 inhibition; v) co-inhibition of other molecules important for survival [proteasome, HDAC and Signal transducers and activators of transcription (Stat)3] and the major pathways activated in melanoma; vi) simultaneous targeting of multiple anti-apoptotic molecules. Here we review the anti-melanoma efficacy and mechanism of action of the above-mentioned combinatorial strategies, together with the potential clinical application of the most promising studies that may eventually lead to therapeutic benefit.

The antiproliferative effect of C2-ceramide on lung cancer cells through apoptosis by inhibiting Akt and NFκB

The anticancer effects of ceramide have been reported in many types of cancers but less in lung cancer. In this study, we used C₂-ceramide to further investigate its possible anticancer effects and mechanisms on non-small cell lung cancer (NSCLC) H1299 cells. The result of cell proliferation in terms of trypan blue assay showed high dose of C₂-ceramide inhibited cell survival after 24 h treatment. The flow cytometry-based assays indicated the effect of apoptosis, chromatin condensation, and G₁ arrest in terms of Annexin V/propidium iodide (PI), DAPI, and PI stainings, respectively. Moreover, the decreased protein level of p-Akt, p-NFκB, survivin and cyclin A2 were detected by Western blot assay. Taken together, these results indicated the antiproliferative effect of C₂-ceramide is majorly responsible for cell apoptosis in lung cancer H1299 cells.

Synthesis and antiproliferative evaluation of 9-methoxy-6-(piperazin-1-yl)-11H-indeno[1,2-c]quinoline-11-one derivatives. Part 4

A number of 6,11-disubstituted indenoquinolines were synthesized and evaluated for their antiproliferative activities and mechanism studies.

The Bruton tyrosine kinase (BTK) inhibitor PCI-32765 synergistically increases proteasome inhibitor activity in diffuse large-B cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) cells sensitive or resistant to bortezomib

Interactions between the Bruton tyrosine kinase (BTK) inhibitor PCI-32765 and the proteasome inhibitor (bortezomib) were examined in diffuse large-B cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) cells, including those highly resistant to bortezomib. Co-administration of PCI-32765/bortezomib synergistically increased mitochondrial injury and apoptosis in germinal centre- or activated B-cell-like-DLBCL cells and in MCL cells. These events were accompanied by marked AKT and nuclear factor (NF)-κB (NFKB1) inactivation, down-regulation of Mcl-1 (MCL1), Bcl-xL (BCL2L1), and XIAP, and enhanced DNA damage (e.g., γH2A.X formation) and endoplasmic reticulum (ER) stress. Similar interactions were observed in highly bortezomib-resistant DLBCL and MCL cells, and in primary DLBCL cells. In contrast, PCI-32765/bortezomib regimens displayed minimal toxicity toward normal CD34(+) bone marrow cells. Transfection of DLBCL cells with a constitutively active AKT construct attenuated AKT inactivation and significantly diminished cell death, whereas expression of an NF-κB "super-repressor" (IκBαser34/36 ) increased both PCI-32765 and bortezomib lethality. Moreover, cells in which the ER stress response was disabled by a dominant-negative eIF2α construct were resistant to this regimen. Finally, combined exposure to PCI-32765 and bortezomib resulted in more pronounced and sustained reactive oxygen species (ROS) generation, and ROS scavengers significantly diminished lethality. Given promising early clinical results for PCI-32765 in DLBCL and MCL, a strategy combining BTK/proteasome inhibitor warrants attention in these malignancies.

A phase 1 Bayesian dose selection study of bortezomib and sunitinib in patients with refractory solid tumor malignancies

BACKGROUND

This phase 1 trial utilising a Bayesian continual reassessment method evaluated bortezomib and sunitinib to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLT), and recommended doses of the combination.

METHODS

Patients with advanced solid organ malignancies were enrolled and received bortezomib weekly with sunitinib daily for 4 weeks, every 6 weeks. Initial doses were sunitinib 25 mg and bortezomib 1 mg m(-2). Cohort size and dose level estimation was performed utilising the Escalation with Overdose Control (EWOC) adaptive method. Seven dose levels were evaluated; initially, sunitinib was increased to a goal dose of 50 mg with fixed bortezomib, then bortezomib was increased. Efficacy assessment occurred after each cycle using RECIST criteria.

RESULTS

Thirty patients were evaluable. During sunitinib escalation, DLTs of grade 4 thrombocytopenia (14%) and neutropenia (6%) at sunitinib 50 mg and bortezomib 1.3 mg m(-2) were seen. Subsequent experience showed tolerability and activity for sunitinib 37.5 mg and bortezomib 1.9 mg m(-2). Common grade 3/4 toxicities were neutropenia, thrombocytopenia, hypertension, and diarrhoea. The recommended doses for further study are bortezomib 1.9 mg m(-2) and sunitinib 37.5 mg. Four partial responses were seen. Stable disease >6 months was noted in an additional six patients.

CONCLUSION

Bortezomib and sunitinib are well tolerated and have anticancer activity, particularly in thyroid cancer. A phase 2 study of this combination in thyroid cancer patients is planned.

Targeting angiogenesis as a promising modality for the treatment of prostate cancer

Antiangiogenic therapy has been successful for the treatment of solid tumors. Several strategies have been used to target angiogenesis in prostate cancer. These strategies include blocking proangiogenic factors via monoclonal antibodies or small molecule inhibitors targeting downstream signaling effector pathways, or using agents with immune-modulatory effects. This review examines the general concepts of tumor angiogenesis and the key clinical trials that have used these agents and other novel biologics in prostate cancer. Targeting angiogenesis is still a promising treatment strategy in prostate cancer with a rational trial design and combination approach.

Metastatic melanoma - a review of current and future drugs

Background:

Melanoma is one of the most aggressive cancers, and it is estimated that 76,250 men and women will be diagnosed with melanoma of the skin in the USA in 2012. Over the last few decades many drugs have been developed but only in 2011 have new drugs demonstrated an impact on survival in metastatic melanoma.

Methods:

A systematic search of literature was conducted, and studies providing data on the effectiveness of current and/or future drugs used in the treatment of metastatic melanoma were selected for review. This review discusses the advantages and limitations of these agents, evaluating past, current and future clinical trials designed to overcome such limitations.

Results:

To date, there are four drugs approved by the Food and Drug Administration for melanoma (dacarbazine, interleukin-2, ipilimumab and vemurafenib). Despite efforts to develop new drugs, few of them have demonstrated any clinical benefits. Approved in 1975, dacarbazine remains the gold standard in chemotherapy, although ipilimumab and vemurafenib have raised many hopes in the last few years. Combining dacarbazine or other chemotherapy agents with new pharmacological agents may be a new way to achieve better clinical responses in patients with metastatic melanoma.

Discussion:

Advances in the molecular knowledge of melanoma have led to major improvements in the treatment of patients with metastatic melanoma, providing new targets and insights. However, heterogeneity amongst study populations, different approaches to treatment and the different melanoma types and localisations included in the trials makes their comparison difficult. New studies focusing on drugs developed in recent decades are warranted.

Matrine induces apoptosis in human acute myeloid leukemia cells via the mitochondrial pathway and Akt inactivation

Acute myeloid leukemia (AML) is a hematological malignancy characterized by a rapid increase in the number of immature myeloid cells in bone marrow. Despite recent advances in the treatment, AML remains an incurable disease. Matrine, a major component extracted from Sophora flavescens Ait, has been demonstrated to exert anticancer effects on various cancer cell lines. However, the effects of matrine on AML remain largely unknown. Here we investigated its anticancer effects and underlying mechanisms on human AML cells in vitro and in vivo. The results showed that matrine inhibited cell viability and induced cell apoptosis in AML cell lines as well as primary AML cells from patients with AML in a dose- and time-dependent manner. Matrine induced apoptosis by collapsing the mitochondrial membrane potential, inducing cytochrome c release from mitochondria, reducing the ratio of Bcl-2/Bax, increasing activation of caspase-3, and decreasing the levels of p-Akt and p-ERK1/2. The apoptotic effects of matrine on AML cells were partially blocked by a caspase-3 inhibitor Z-DEVD-FMK and a PI3K/Akt activator IGF-1, respectively. Matrine potently inhibited in vivo tumor growth following subcutaneous inoculation of HL-60 cells in SCID mice. These findings indicate that matrine can inhibit cell proliferation and induce apoptosis of AML cells and may be a novel effective candidate as chemotherapeutic agent against AML.

Blockade of NFκB activity by Sunitinib increases cell death in Bortezomib-treated endometrial carcinoma cells

Endometrial carcinoma is one of the most common malignancies in the female genital tract, usually treated by surgery and radiotherapy. Chemotherapy is used when endometrial carcinoma is associated with widespread metastasis or when the tumor recurs after radiation therapy. In the present study, we demonstrate that the tyrosine kinase receptor inhibitor Sunitinib reduces cell viability, proliferation, clonogenicity and induces apoptotic cell death in endometrial carcinoma cell lines, which is not due to its action through the most known targets like VEGFR, nor through EGFR as demonstrated in this work. Interestingly, Sunitinib reduces NFκB transcriptional activity either at basal level or activation by EGF or TNF-α. We observed that Sunitinib was able to inhibit the Bortezomib-induced NFκB transcriptional activity which correlates with a decrease of the phosphorylated levels of IKKα and β, p65 and IκBα. We evaluated the nature of the interaction between Sunitinib and Bortezomib by the dose effect method and identified a synergistic effect (combination index < 1). Analogously, silencing of p65 expression by lentiviral-mediated short-hairpin RNA delivery in Bortezomib treated cells leads to a strongly increased sensitivity to Bortezomib apoptotic cell death. Altogether our results suggest that the combination of Sunitinib and Bortezomib could be considered a promising treatment for endometrial carcinoma after failure of surgery and radiation.

Functional expression of voltage-gated calcium channels in human melanoma

The expression of voltage-gated calcium channels (VGCCs) has not been reported previously in melanoma cells in spite of increasing evidence of a role of VGCCs in tumorigenesis and tumour progression. To address this issue we have performed an extensive RT-PCR analysis of VGCC expression in human melanocytes and a range of melanoma cell lines and biopsies. In addition, we have tested the functional expression of these channels using Ca(2+) imaging techniques and examined their relevance for the viability and proliferation of the melanoma cells. Our results show that control melanocytes and melanoma cells express channel isoforms belonging to the Ca(v) 1 and Ca(v) 2 gene families. Importantly, the expression of low voltage-activated Ca(v) 3 (T-type) channels is restricted to melanoma. We have confirmed the function of T-type channels as mediators of constitutive Ca(2+) influx in melanoma cells. Finally, pharmacological and gene silencing approaches demonstrate a role for T-type channels in melanoma viability and proliferation. These results encourage the analysis of T-type VGCCs as targets for therapeutic intervention in melanoma tumorigenesis and/or tumour progression.