Target For Treatment Of Melanoma Research Articles

Erythroid Differentiation Regulator 1, an Interleukin 18-Regulated Gene, Acts as a Metastasis Suppressor in Melanoma

Erythroid differentiation regulator (Erdr1) was first discovered in mouse leukemia cell lines and functions as a stress-related survival factor. This study investigated whether Erdr1 regulates murine melanoma progression, as well as the mechanism involved in Erdr1-regulated metastasis. The expression of Erdr1 is negatively correlated with IL-18 expression, which has a pro-cancer effect in melanoma. To study the role of Erdr1 as an anti-cancer factor, cell migration, invasion, and proliferation were measured. Erdr1 overexpression markedly inhibited the level of cell migration, invasion, and proliferation in B16F10 cells in vitro. In addition, Erdr1 overexpression significantly suppressed melanoma lung colonization, metastasis, and tumor growth in vivo. To identify the factors involved in Erdr1-reduced metastasis, heat shock protein 90 (HSP90), a well-known stress protein and contributor to tumor metastasis, was examined. We found that HSP90 was significantly decreased in Erdr1-overexpressing cells. Functional analysis demonstrated that HSP90 small-interfering RNA transfection reduced the migration ability and metastasis of melanoma. In conclusion, Erdr1 shows a powerful anti-metastasis effect that leads to the ability to reduce the metastatic potential of murine malignant melanoma cells. Erdr1 is an anti-metastatic factor that may be a possible therapeutic target for treatment of melanoma.

Abstract 2435: Validation of Cynomolgus monkeys as relevant species for safety assessment of a novel human BiTE antibody platform for cancer therapy

Abstract Nonclinical safety assessment of biopharmaceuticals for human use relies on their cross-reactivity with the respective target in other species, the absence of which precludes testing in commonly used animal models. This is the case for a first-generation of T cell-engaging BiTE antibodies, which solely cross-react with T cells of chimpanzee. BiTE antibodies are designed to transiently connect the CD3 subunit of T cell receptors on T cells with an antigen on target cells. This can very effectively activate T cells, leading to a potent redirected lysis of target cells. Here, we have generated a series of novel human anti-CD3 antibodies that cross-react with non-human primate species, including Cynomolgus monkeys (Macaca fascicularis) and marmoset (Callithrix jacchus). The variable domains of a selected anti-CD3 antibody were used to generate next-generation BiTE antibodies specific for (1) CD33, a target antigen for treatment of acute myelogenous leukemia, (2) melanoma-associated chondroitin sulfate proteoglycan (MCSP), a potential target for treatment of melanoma, and (3) epidermal growth factor receptor 1 (EGFR), a validated target for treatment of colorectal cancer. In vitro, CD33-, MCSP- and EGFR-specific BiTE antibodies showed comparable binding to CD3 on human and macaque T cells, and to CHO cells expressing CD33, MCSP and EGFR of human or macaque origin. In human and macaque cell-based assays, bispecific binding triggered redirected target cell lysis as well as conditional T cell activation, as previously described for first-generation BiTE antibodies. When continuously infused for one week to Cynomolgus monkeys, the CD33-specific BiTE antibody caused depletion of CD33-expressing peripheral blood cells at tolerated doses, and reached a maximum tolerated dose (MTD) at 120 µg/m2/day. The EGFR-specific BiTE antibody reached an MTD at 150 µg/m2/kg. In contrast, the MCSP-specific BiTE antibody was well-tolerated up to a dose of 5,000 µg/m2/day. Our primate data suggest that the tolerability and toxicity of CD33-, MCSP- and EGFR-specific BiTE antibodies were apparently determined by target cell-dependent bispecific binding, and not by monovalent binding to CD3 on macaque T cells. Our data validate the Cynomolgus monkey as a relevant species for assessing the safety and tolerability of next-generation BiTE antibodies that use a more broadly cross-reactive anti-CD3 human single-chain antibody. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2435.

Abstract 659: Overexpression of TPX2 accelerates cell cycle progression in melanoma and is an indicator of response to Aurora A kinase inhibitors

Abstract There is a tremendous need to identify more effective treatments for metastatic melanoma. In order to detect genetic changes in melanoma that might facilitate the development of novel therapies, we performed aCGH in melanoma cell lines and tumors and identified that Targeting Protein for Xklp2 (TPX2) was the most commonly amplified gene on 20q11.21, a region of frequent gain. Gene expression profiling studies also demonstrated overexpression of TPX2, suggesting a previously unknown role in the development of melanoma. TPX2 is a microtubule-associated protein that regulates bipolar spindle assembly and centrosome replication; the TPX2 - Aurora A interaction is essential for accurate segregation of chromosome and mitosis progression. We evaluated a potential role for TPX2 overexpression in melanoma using TPX2 overexpressing melanoma cell lines as a model. TPX2 overexpressing cell lines display accelerated cell cycle progression, increased CDK1/CDK2 activity, cyclin A/B1 levels, and constitutive activation and overexpression of Aurora A. We depleted TPX2 using shRNA to further dissect its role in melanoma. In unsynchronized cells, TPX2 depletion causes prolonged mitotic arrest accompanied by persistent activation of the spindle-assembly checkpoint (SAC) and caspase-3, and subsequent caspase-dependent cell death. In contrast, with G1/S synchronization, TPX2 depletion decreases S phase entry and delays S-G2-M phase transition followed by marked cell death. Accordingly, TPX2 depletion was associated with decreased CDK1 activity but not CDK2 activity, and activation of caspase and low activation of the SAC. Our data demonstrate that TPX2 overexpression is required for increased CDK1-cyclinB1 activity, thus accelerating cell cycle progression. Accordingly, TPX2-overexpressing melanoma cell lines are dependent on TPX2 for proliferation, whereas non-overexpressing cell lines and melanocytes are not. Additionally, TPX2-overexpressing cell lines are 3-10 time more sensitive to an Aurora A kinase inhibitor (VX680) than non-overexpressing cell line, suggesting that TPX2-activating Aurora A kinase could become a novel therapeutic target for treatment of melanoma with highly expressed TPX2, Finally, TPX2-IHC staining demonstrated that a significantly increased expression of TPX2 in primary and metastatic melanoma as compared to begin nevi, suggesting it is a marker of progression. Thus, we have identified TPX2 as a novel gene upregulated in melanoma. Overexpression of TPX2 may be a marker of tumors sensitive to Aurora A inhibitors allowing patient stratification for optimal therapeutic selection. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 659.

Abstract 2564: High-throughput siRNA library screen for discovery and identification of new melanoma therapeutic targets in combination with antioxidant pretreatment

Abstract Melanoma is one of the most prevalent cancers in the United States, having the fifth highest cancer incidence in males and sixth highest incidence in females. Primary cutaneous melanoma can often be cured by surgery, but for those patients in whom metastasis has occurred, mortality is high in part due to numerous chemoresistance mechanisms. Thus, there is an urgent need to discover and identify novel therapeutic targets for the efficient treatment of this lethal disease. Gene silencing by RNA interference (RNAi) is a powerful tool to identify novel genes involved in specific biological processes. In our study, we used high-throughput druggable siRNA library (Dharmacon) targeting 6028 human genes to screen metastatic melanoma cell lines and found that knockdown of gene expression by siRNA pools targeting 885 genes significantly inhibited melanoma growth (p<0.005). Among them, 67 siRNA pools resulted in >50% inhibition of cell viability in the melanoma A375 cells which we employed for the screening analysis. We validated the top-six cancer-related genes (RRM2, BCAR3, PSMA2, UBB, RRM1, TCP1) as potential melanoma therapeutic target candidates, as knockdown of these 6 genes significantly inhibited cell growth and induced apoptosis in multiple melanoma cell lines. We have hypothesized that antioxidant treatment relieves resistance mechanisms, and showed that among the screened >6000 siRNA pools, treatment with 20 pools significantly increased the growth inhibition in the presence of nontoxic levels of bardoxolone methyl (p<0.005), a novel semi-synthetic triterpenoid (previously known as CDDO-Me) with potent antioxidant activity generously provided by Reata Pharmaceuticals. We also selected 5 additional cancer-related genes (GNPAT, SUMO1, SPINT2, FLI1 and SSX1) for further analysis and validated them as additional candidates for therapeutic targeting in the presence of antioxidant. Our results thus demonstrate the feasibility of the high-throughput siRNA library screen system in discovering new melanoma therapeutic targets and shows that these new candidate genes are promising for the development of novel therapeutic targets for melanoma treatment, many of which are revealed by antioxidant pretreatment. Results from our study provide the basis for significant advances in identifying targets for the treatment of melanoma patients. (This study was partially supported by the grant from the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation and the NIH Melanoma SPORE grant P50, CA093459). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2564.

Abstract 1175: PCR array-based gene expression profiling identifies CD70 and CD74 as molecular markers and potential therapeutic targets for human melanoma

Abstract Melanoma is one of the most prevalent cancers. While early detection and surgical excision can cure melanoma, patients with advanced disseminated disease have a very poor prognosis due to its extremely aggressive growth characteristics and high resistance to chemotherapy and radiation. Improvement of our understanding of the mechanisms that lead to progression of metastatic melanoma, as well as development of novel therapeutic strategies are urgently required for patients. In our study, we applied PCR arrays and bioinformatics analysis to evaluate gene expression of metastatic melanoma cells and normal skin cells. We used the Human Inflammatory Cytokine and Receptors RT2 Profiler™ PCR Array to analyze the differential expression of genes in metastatic melanoma cell lines (A375) and primary normal epidermal melanocytes (NHEM), which are the precursor cell of melanoma. We found the 43 genes were highly expressed in A375 which were upregulated by more than 20 fold in comparison to NHEM. We next selected the top-ten differentially expressed genes (CD70, IL-1β, MGLL, SERPINA3, MDK, IL13RA2, CD74, VEGFA, CXCL1, and IL8), whose expression levels in A375 cells were > 250-fold higher than in the primary normal NHEM, for further validation. The results from our RT-PCR, immunoblot, immunocytochemistry (ICC) and tissue microarray (TMA) analysis showed that CD70, SERPINA3, IL13RA2 and CD74 genes were highly expressed at mRNA and protein levels in various melanoma cell lines and metastatic melanoma tumor tissues. A much lower level of expression of each gene was detected in normal human skin cell lines and normal skin tissues. These results thus demonstrated that the four genes identified by our PCR array are likely of molecular markers and should be pursued as therapeutic targets for melanoma treatment. To further verify their potentials as potential melanoma therapeutic targets, we also evaluated the effects of siRNAs targeting CD70 and CD74 genes and the monoclonal antibodies against CD70 and CD74 proteins for regulation of melanoma growth. Treatment with CD70 or CD74-specific siRNAs and also monoclonal antibodies dramatically inhibited cell growth in various melanoma cell lines, indicating that CD70 and CD74 are also attractive molecular targets in the treatment of human metastatic melanoma. Our findings have important implications in understanding the metastatic process of melanoma and discovering novel therapeutic strategies for melanoma treatment. The molecular markers and therapeutic targets developed in this study will have a direct and immediate translational application. If successful, our study will represent a significant advance in the diagnosis and treatment of melanoma. (This study was partially supported by the grant from the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation and the Melanoma SPORE grant from the NCI, P50, CA093459). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1175.

Notch1 is an effector of Akt and hypoxia in melanoma development

Melanomas are highly aggressive neoplasms resistant to most conventional therapies. These tumors result from the interaction of altered intracellular tumor suppressors and oncogenes with the microenvironment in which these changes occur. We previously demonstrated that physiologic skin hypoxia contributes to melanomagenesis in conjunction with Akt activation. Here we show that Notch1 signaling is elevated in human melanoma samples and cell lines and is required for Akt and hypoxia to transform melanocytes in vitro. Notch1 facilitated melanoma development in a xenograft model by maintaining cell proliferation and by protecting cells from stress-induced cell death. Hyperactivated PI3K/Akt signaling led to upregulation of Notch1 through NF-kappaB activity, while the low oxygen content normally found in skin increased mRNA and protein levels of Notch1 via stabilization of HIF-1alpha. Taken together, these findings demonstrate that Notch1 is a key effector of both Akt and hypoxia in melanoma development and identify the Notch signaling pathway as a potential therapeutic target in melanoma treatment.

Thrombospondin-1 and Cutaneous Melanoma

Background: Thrombospondins (TSPs) are recognized as important glycoproteins that regulate a wide variety of cell functions and interactions. TSPs in malignant tumors can both enhance and inhibit tumor progression, invasion, and metastasis, depending on cell type, stromal interactions, and microenvironment. These proteins are potential targets for anticancer therapy. Objective: The aim of our article is to review the role of thrombospondin-1 (TSP1) in cutaneous melanoma. Conclusions: TSP1 expression is variable in melanoma cell lines and tumors. Similar to findings in other human cancers, expression of TSP1 by melanoma cells usually inhibits tumor progression via the antiangiogenic effect of TSP1. Conversely, stromal TSP1 overexpression in melanoma is a poor prognostic factor associated with decreased survival. Understanding the interactions of TSP1 with other melanoma- and matrix-associated proteins should provide new prognostic indices and possible therapeutic targets for melanoma treatment.