Age-related increases in fibroblast-secreted IGFBP2 increase melanoma cell invasion and lipid synthesis.

Aged melanoma patients (>65 years old) have more aggressive disease relative to young patients (<55 years old) for reasons that are not completely understood. Analysis of the young and aged secretome from human dermal fibroblasts identified >5-fold levels of insulin-like growth factor binding protein 2 (IGFBP2) in the aged fibroblast secretome. IGFBP2 functionally triggers upregulation of the PI3K-dependent fatty acid biosynthesis program in melanoma cells. Melanoma cells co-cultured with aged dermal fibroblasts have higher levels of lipids relative to co-cultured with young dermal fibroblasts, which can be lowered by silencing IGFBP2 expression in fibroblasts, prior to treating with conditioned media. Conversely, ectopically treating melanoma cells with recombinant IGFBP2 in the presence of conditioned media from young fibroblasts, or overexpressing IGFBP2 in melanoma cells promoted lipid synthesis and accumulation in the melanoma cells. Treatment of young mice with rIGFBP2 increases tumor growth. Neutralizing IGFBP2 in vitro reduces migration and invasion in melanoma cells, and in vivo studies demonstrate that neutralizing IGFBP2 in syngeneic aged mice reduces tumor growth amd metastasis. Our results suggest that aged dermal fibroblasts increase melanoma cell aggressiveness through increased secretion of IGFBP2, stressing the importance of considering age when designing studies and treatment.

Age-dependent loss of HAPLN1 erodes vascular integrity via indirect upregulation of endothelial ICAM1 in melanoma.

Melanoma, the most lethal form of skin cancer, often has worse outcomes in older patients. We previously demonstrated that an age-related decrease in the secreted extracellular matrix (ECM) protein HAPLN1 has a role in slowing melanoma progression. Here we show that HAPLN1 in the dermal ECM is sufficient to maintain the integrity of melanoma-associated blood vessels, as indicated by increased collagen and VE-cadherin expression. Specifically, we show that HAPLN1 in the ECM increases hyaluronic acid and decreases endothelial cell expression of ICAM1. ICAM1 phosphorylates and internalizes VE-cadherin, a critical determinant of vascular integrity, resulting in permeable blood vessels. We found that blocking ICAM1 reduces tumor size and metastasis in older mice. These results suggest that HAPLN1 alters endothelial ICAM1expression in an indirect, matrix-dependent manner. Targeting ICAM1 could be a potential treatment strategy for older patients with melanoma, emphasizing the role of aging in tumorigenesis.

Collagen VI deposition mediates stromal T cell trapping through inhibition of T cell motility in the prostate tumor microenvironment.

The tumor extracellular matrix (ECM) is a barrier to anti-tumor immunity in solid tumors by disrupting T cell-tumor cell interaction underlying the need for elucidating mechanisms by which specific ECM proteins impact T cell motility and activity within the desmoplastic stroma of solid tumors. Here, we show that Collagen VI (Col VI) deposition correlates with stromal T cell density in human prostate cancer specimens. Furthermore, motility of CD4+ T cells is completely ablated on purified Col VI surfaces when compared with Fibronectin and Collagen I. Importantly, T cells adhered to Col VI surfaces displayed reduced cell spreading and fibrillar actin, indicating a reduction in traction force generation accompanied by a decrease in integrin ß1 clustering. We found that CD4+ T cells largely lack expression of integrin α1 in the prostate tumor microenvironment and that blockade of α1ß1 integrin heterodimers inhibited CD8+ T cell motility on prostate fibroblast-derived matrix, while re-expression of ITGA1 improved motility. Taken together, we show that the Col VI-rich microenvironment in prostate cancer reduces the motility of CD4+ T cells lacking integrin α1, leading to their accumulation in the stroma, thus putatively inhibiting anti-tumor T cell responses.

Age-related increases in IGFBP2 increase melanoma cell invasion and lipid synthesis.

Aged melanoma patients (>65 years old) have more aggressive disease relative to young patients (<55 years old) for reasons that are not completely understood. Analysis of the young and aged secretome from human dermal fibroblasts identified >5-fold levels of insulin-like growth factor binding protein 2 (IGFBP2) in the aged fibroblast secretome. IGFBP2 functionally triggers upregulation of the PI3K-dependent fatty acid biosynthesis program in melanoma cells through increases in FASN. Melanoma cells co-cultured with aged dermal fibroblasts have higher levels of lipids relative to young dermal fibroblasts, which can be lowered by silencing IGFBP2 expression in fibroblasts, prior to treating with conditioned media. Conversely, ectopically treating melanoma cells with recombinant IGFBP2 in the presence of conditioned media from young fibroblasts, promoted lipid synthesis and accumulation in the melanoma cells. Neutralizing IGFBP2 in vitro reduces migration and invasion in melanoma cells, and in vivo studies demonstrate that neutralizing IGFBP2 in syngeneic aged mice, ablates tumor growth as well as metastasis. Conversely, ectopic treatment of young mice with IGFBP2 in young mice increases tumor growth and metastasis. Our data reveal that aged dermal fibroblasts increase melanoma cell aggressiveness through increased secretion of IGFBP2, stressing the importance of considering age when designing studies and treatment. Significance: The aged microenvironment drives metastasis in melanoma cells. This study reports that IGFBP2 secretion by aged fibroblasts induces FASN in melanoma cells and drives metastasis. Neutralizing IGFBP2 decreases melanoma tumor growth and metastasis.