Cancer is a disease of aging, and aged cancer patients have a poorer prognosis. This may be due to accumulated cellular damage, decreases in adaptive immunity, and chronic inflammation. However, the effects of the aged microenvironment on tumor progression have been largely unexplored. Since dermal fibroblasts can have profound impacts on melanoma progression1–4 we examined whether age-related changes in dermal fibroblasts could drive melanoma metastasis and response to targeted therapy. We find that aged fibroblasts secrete a Wnt antagonist, sFRP2, which activates a multi-step signaling cascade in melanoma cells that results in a decrease in β-catenin and MITF, and ultimately the loss of a key redox effector, APE1. Loss of APE1 attenuates the response of melanoma cells to ROS-induced DNA damage, rendering them more resistant to targeted therapy (vemurafenib). Age-related increases in sFRP2 also augment both angiogenesis and metastasis of melanoma cells. These data provide an integrated view of how fibroblasts in the aged microenvironment contribute to tumor progression, offering new paradigms for the design of therapy for the elderly.

The MYC oncogene is frequently mutated and overexpressed in human renal cell carcinoma (RCC). However, there have been no studies on the causative role of MYC or any other oncogene in the initiation or maintenance of kidney tumorigenesis. Here, we show through a conditional transgenic mouse model that the MYC oncogene, but not the RAS oncogene, initiates and maintains RCC. Desorption electrospray ionization-mass-spectrometric imaging was used to obtain chemical maps of metabolites and lipids in the mouse RCC samples. Gene expression analysis revealed that the mouse tumors mimicked human RCC. The data suggested that MYC-induced RCC up-regulated the glutaminolytic pathway instead of the glycolytic pathway. The pharmacologic inhibition of glutamine metabolism with bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl) ethyl sulfide impeded MYC-mediated RCC tumor progression. Our studies demonstrate that MYC overexpression causes RCC and points to the inhibition of glutamine metabolism as a potential therapeutic approach for the treatment of this disease.MYC oncogene | renal cell carcinoma | desorption electrospray ionization mass spectrometry imaging | glutamine metabolism R enal cell adenocarcinoma (RCC) is a kidney cancer that originates in the lining of the proximal convoluted tubule, a part of the very small tubes in the kidney that transport waste molecules from the blood to the urine. Most patients who present with advanced RCC have a dismal prognosis because RCC easily metastasizes and advances in therapy have been limited (1-3). A lack of transgenic models of RCC has made it difficult to identify and test new therapeutic modalities.The MYC pathway is activated in most cases of human RCC (4), genomically amplified in 5-10% of patients, overexpressed in 20% (5), and associated with a hereditary RCC syndrome (6) suggesting a causal role in the pathogenesis, but this has never been examined. Here, we report the development of a conditional transgenic mouse model for MYC-deregulated human RCC. The MYC oncogene contributes to tumorigenesis of many types of cancer through various mechanisms (7-10), including the regulation of proliferation and growth, protein and ribosomal biogenesis, changes in metabolism, lipid synthesis, and induction of angiogenesis (11)(12)(13)(14). MYC reprogramming can result in tumors that are addicted to glucose and/or glutamine for their energy metabolism (15-19). MYC directly regulates specific genes of the glycolytic and glutaminolytic pathways (15,17,20,21), including lactate dehydrogenase A (LDHA), glucose transporter 1 (Glut1), hexokinase 2 (HK2), phosphofructokinase-M 1 (PFKM1), and enolase 1 (Eno1) (21-23). Also, MYC coordinates genes involved in glutamine catabolism (SI MYC and Glutamine Catabolism). However, there has been no evidence to show that MYC overexpression directly drives and maintains RCC or how this occurs.Through our new transgenic mouse model, we showed that transgenic MYC, but not mutant RAS, overexpression in vivo rapidly initiates a highly aggressive RCC that histologi...

We have previously shown that Wnt5A drives invasion in melanoma. We have also shown that Wnt5A promotes resistance to therapy designed to target the BRAFV600E mutation in melanoma. Here, we show that melanomas characterized by high levels of Wnt5A respond to therapeutic stress by increasing p21 and expressing classical markers of senescence, including positivity for senescence-associated β-galactosidase (SA-β-gal), senescence associated heterochromatic foci (SAHF), H3K9Me chromatin marks, and PML bodies. We find that despite this, these cells retain their ability to migrate and invade. Further, despite the expression of classic markers of senescence like SA-β-gal and SAHF, these Wnt5A-high cells are able to colonize the lungs in in vivo tail-vein colony forming assays. This clearly underscores the fact that these markers do not indicate true senescence in these cells, but instead an adaptive stress response that allows the cells to evade therapy and invade. Notably, silencing Wnt5A reduces expression of these markers and decreases invasiveness. The combined data point to Wnt5A as a master regulator of an adaptive stress response in melanoma, which may contribute to therapy resistance.

Mammalian spermatogenesis is a complex differentiation process that occurs in several stages in the seminiferous tubules of the testes. Currently, there is no reliable cell culture system allowing for spermatogenic differentiation in vitro, and most biological studies of spermatogenic cells require tissue harvest from animal models like the mouse and rat. Because the testis contains numerous cell types -both nonspermatogenic (Leydig, Sertoli, myeloid, and epithelial cells) and spermatogenic (spermatogonia, spermatocytes, round spermatids, condensing spermatids and spermatozoa) -studies of the biological mechanisms involved in spermatogenesis require the isolation and enrichment of these different cell types. The STA-PUT method allows for the separation of a heterogeneous population of cells -in this case, from the testesthrough a linear BSA gradient. Individual cell types sediment with different sedimentation velocity according to cell size, and fractions enriched for different cell types can be collected and utilized in further analyses. While the STA-PUT method does not result in highly pure fractions of cell types, e.g. as can be obtained with certain cell sorting methods, it does provide a much higher yield of total cells in each fraction (~1 x 10 8 cells/spermatogenic cell type from a starting population of 7-8 x 10 8 cells). This high yield method requires only specialized glassware and can be performed in any cold room or large refrigerator, making it an ideal method for labs that have limited access to specialized equipment like a fluorescence activated cell sorter (FACS) or elutriator. Video LinkThe video component of this article can be found at

Purpose Aging is a poor prognostic factor for melanoma. We have shown that melanoma cells in an aged microenvironment, are more resistant to targeted therapy than identical cells in a young microenvironment. This is dependent on age-related secreted factors. Klotho is an age-related protein, whose serum levels decrease dramatically by age 40. Most studies on klotho in cancer have focused on the expression of klotho in the tumor cell. We have shown that exogenous klotho inhibits internalization and signaling of Wnt5A, which drives melanoma metastasis and resistance to targeted therapy. We investigate here whether increasing klotho in the aged microenvironment could be an effective strategy for the treatment of melanoma. Experimental Design PPARγ increases klotho levels, and is increased by glitazones. Using rosiglitazone, we queried the effects of rosiglitazone on Klotho/ Wnt5A crosstalk, in vitro and in vivo, and the implications of that for targeted therapy in young vs. aged animals. Results We show that rosiglitazone increases klotho and decreases Wnt5A in tumor cells, reducing the burden of both BRAF-inhibitor sensitive, and BRAF inhibitor-resistant tumors in aged, but not young mice. However, when used in combination with PLX4720, tumor burden was reduced in both young and aged mice, even in resistant tumors. Conclusions Using glitazones as adjuvant therapy for melanoma may provide a new treatment strategy for older melanoma patients who have developed resistance to vemurafenib. As klotho has been shown to play a role in other cancers too, our results may have wide relevance for multiple tumor types.

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Melanoma is an aggressive disease. Although about 13% of melanoma cases are diagnosed at metastatic stage, the 5-year survival rate for these patients is 16%. We have previously shown that metastatic melanoma cells express high levels of Wnt5a. Wnt5a is a member of the Wnt family of proteins, which play an important role during development and tumorigenesis. In melanoma, Wnt5a signaling is mediated by an autocrine loop that also modulates the activity of midkine. Midkine is a 16kDa protein that is elevated in many different cancers. Overexpression of midkine promotes the growth, migration, survival and angiogenic capability of the tumors. However, the molecular mechanisms that regulate the activity of midkine are unknown, especially in metastatic melanoma. We asked whether Wnt5a can positively regulate the functions of midkine to promote the progression of metastatic melanoma. To address this, we analyzed melanoma cells for midkine expression and observed that Wnt5a high melanoma cells also express high levels of midkine. Further, an increase in Wnt5a signaling by treatment with recombinant Wnt5a led to an increased midkine signaling. By performing 3D spheroid assays, we observed that higher expression of midkine is correlated with an increased metastatic ability of the cells. The expression of midkine also correlated with an increased resistance to BRAF inhibitors in BRAF V600E mutated melanoma. This indicates that midkine may signal through MAPK pathway to affect invasion and drug resistance in metastatic melanoma. Developing adjuvant therapies targeting midkine can prolong the overall survival of patients with metastatic melanoma. Citation Format: Amanpreet Kaur, Michael O'Connell, Marie Webster, Reeti Behera, Vanessa Dang, Abibatou Ndoye, Ashani Weeraratna. Midkine as a potential target for combating drug resistance and invasion in melanoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5092. doi:10.1158/1538-7445.AM2015-5092