The tumor cell-secreted matricellular protein WISP1 drives pro-metastatic collagen linearization.

Collagen linearization is a hallmark of aggressive tumors and a key pathogenic event that promotes cancer cell invasion and metastasis. Cell-generated mechanical tension has been proposed to contribute to collagen linearization in tumors, but it is unknown whether other mechanisms play prominent roles in this process. Here, we show that the secretome of cancer cells is by itself able to induce collagen linearization independently of cell-generated mechanical forces. Among the tumor cell-secreted factors, we find a key role in this process for the matricellular protein WISP1 (CCN4). Specifically, WISP1 directly binds to type I collagen to promote its linearization in vitro (in the absence of cells) and in vivo in tumors. Consequently, WISP1-induced type I collagen linearization facilitates tumor cell invasion and promotes spontaneous breast cancer metastasis, without significantly affecting gene expression. Furthermore, higher WISP1 expression in tumors from cancer patients correlates with faster progression to metastatic disease and poor prognosis. Altogether, these findings reveal a conceptually novel mechanism whereby pro-metastatic collagen linearization critically depends on a cancer cell-secreted factor.

Matricellular Protein WISP2 Is an Endogenous Inhibitor of Collagen Linearization and Cancer Metastasis.

Collagen remodeling contributes to many physiologic and pathologic processes. In primary tumors, the linearization of collagen fibers promotes cancer cell invasion and metastasis and is indicative of poor prognosis. However, it remains unknown whether there are endogenous inhibitors of collagen linearization that could be exploited therapeutically. Here, we show that collagen linearization is controlled by two secreted matricellular proteins with antagonistic functions. Specifically, WISP1 was secreted by cancer cells, bound to type I collagen (Col I), and linearized Col I via its cysteine-rich C-terminal (CT) domain. In contrast, WISP2, which lacks a CT domain, inhibited Col I linearization by preventing WISP1-Col I binding. Analysis of patient data revealed that WISP2 expression is lower in most solid tumors, in comparison with normal tissues. Consequently, genetic or pharmacologic restoration of higher WISP2 levels impaired collagen linearization and prevented tumor cell invasion and metastasis in vivo in models of human and murine breast cancer. Thus, this study uncovers WISP2 as the first inhibitor of collagen linearization ever identified and reveals that collagen architecture can be normalized and metastasis inhibited by therapeutically restoring a high WISP2:WISP1 ratio. SIGNIFICANCE: Two secreted factors, WISP1 and WISP2, antagonistically regulate collagen linearization, and therapeutically increasing the WISP2:WISP1 ratio in tumors limits collagen linearization and inhibits metastasis.See related commentary by Barcus and Longmore, p. 5611.