Aging Microenvironment Modulates Melanoma Invasion And Metastasis

The incidence of melanoma rises dramatically after the age of 55. Due to an increase in aging population, it is important to study the change in molecular mechanisms due to aging that would allow development of therapies that are tailored to the age of the patients. The role of the tumor microenvironment in modulating cancer characteristics is widely recognized and it also provides targets for therapeutic intervention. Due to this, we hypothesized that changes in tumor microenvironment due to aging could affect the progression of the melanoma. We obtained skin fibroblasts from healthy donors aged 25-35, as well as skin fibroblasts from healthy donors aged 55-65. We cultured these fibroblasts and used conditioned media from them to affect the invasion of melanoma cells in 3D spheroid invasion assays, where aged fibroblasts promoted invasion of melanoma cells into collagen. We also built artificial skin (reconstructs) using young and aged fibroblasts and demonstrated that skin built with aged fibroblasts promoted melanoma cell invasion. Finally using a transgenic mouse model of melanoma (Yumm1.7, BRAFV600E/PTEN-/-) we observed that the injection of melanoma cells into the tail vein of aged mice (52 weeks) formed metastastic colonies much more rapidly than those injected into the tail vein of young mice (8 weeks). To study the factors involved in the aging microenvironment, we performed a proteomics study of the secretome from young and aged fibroblasts. From this study, we observed that aged fibroblasts secreted inhibitors of canonical Wnt signaling, as well as increased deposition of extracellular matrix components in the aging microenvironment. Since inhibition of canonical Wnt signaling has been linked to decreased sensitivity towards BRAF inhibitors in melanoma, we injected Yumm 1.7 cells subcutaneously into aged and young mice. These mice were then treated with BRAF inhibitors. We observed an increased resistance in response to therapy in the aged mice. We also prepared skin reconstruct from fibroblasts with knockdown of the proteins that we identified from secretome and treated them with PLX4720. These results indicated the role of these extracellular matrix proteins in melanoma. We are exploring the mechanisms of how these extracellular matrix proteins affect the sensitivity towards chemotherapeutics. We concluded that aging could alter tumor microenvironment thus resulting in increased metastasis and therapy resistance. It is important that the studies in cancer therapies take into account the age of the patient to achieve better response in patients. Citation Format: Amanpreet Kaur, Katie Marchbank, Vanessa Dang, Michael O9Connell, Marie Webster, Jessica Appleton, Phil Cheng, Alexander Valiga, Rachel Morissette, Nazli McDonnell, Luigi Ferrucci, Andrew Kossenkov, Katrina Meeth, Marcus Bosenberg, Hsin-Yao Tang, Xiangfan Yin, William Wood, III, Elin Lehrmann, Kevin Becker, Keith Flaherty, Dennie Frederick, Jennifer Wargo, Katherine Aird, Rugang Zhang, Xiaowei Xu, Qin Liu, David Speicher, Ashani Weeraratna. Aging microenvironment modulates melanoma invasion and metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr A04.