title: Astrocytes facilitate melanoma brain metastasis via secretion of IL-23.
abstract: Melanoma is the leading cause of skin cancer mortality. The major cause of melanoma mortality is metastasis to distant organs, frequently to the brain. The microenvironment plays a critical role in tumourigenesis and metastasis. In order to treat or prevent metastasis, the interactions of disseminated tumour cells with the microenvironment at the metastatic organ have to be elucidated. However, the role of brain stromal cells in facilitating metastatic growth is poorly understood. Astrocytes are glial cells that function in repair and scarring of the brain following injury, in part via mediating neuroinflammation, but the role of astrocytes in melanoma brain metastasis is largely unresolved. Here we show that astrocytes can be reprogrammed by human brain-metastasizing melanoma cells to express pro-inflammatory factors, including the cytokine IL-23, which was highly expressed by metastases-associated astrocytes in vivo. Moreover, we show that the interactions between astrocytes and melanoma cells are reciprocal: paracrine signalling from astrocytes up-regulates the secretion of the matrix metalloproteinase MMP2 and enhances the invasiveness of brain-metastasizing melanoma cells. IL-23 was sufficient to increase melanoma cell invasion, and neutralizing antibodies to IL-23 could block this enhanced migration, implying a functional role for astrocyte-derived IL-23 in facilitating the progression of melanoma brain metastasis. Knocking down the expression of MMP2 in melanoma cells resulted in inhibition of IL-23-induced invasiveness. Thus, our study demonstrates that bidirectional signalling between melanoma cells and astrocytes results in the formation of a pro-inflammatory milieu in the brain, and in functional enhancement of the metastatic potential of disseminated melanoma cells.
authors: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel; Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors: Anat
authors: A
authors: Klein
authors: Hila
authors: H
authors: Schwartz
authors: Orit
authors: O
authors: Sagi-Assif
authors: Tsipi
authors: T
authors: Meshel
authors: Sivan
authors: S
authors: Izraely
authors: Shlomit
authors: S
authors: Ben Menachem
authors: Roman
authors: R
authors: Bengaiev
authors: Amir
authors: A
authors: Ben-Shmuel
authors: Clara
authors: C
authors: Nahmias
authors: Pierre-Olivier
authors: PO
authors: Couraud
authors: Isaac P
authors: IP
authors: Witz
authors: Neta
authors: N
authors: Erez
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism* / Q000556:secondary; D006801:Humans; D053759:Interleukin-23 / Q000378:metabolism*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism* / Q000556:secondary; D008819:Mice, Nude; D015398:Signal Transduction / Q000502:physiology; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology; D015854:Up-Regulation
chemical_list: D053759:Interleukin-23; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse
keywords: IL-23; astrocytes; brain metastasis; melanoma; microenvironment; neuroinflammation