Crosstalk between tumor and stromal cells in the tumor microenvironment alter its properties in ways that facilitate the invasive behavior of tumor cells. Here we demonstrate that cancer-associated fibroblasts (CAF) increase the stiffness of the extracellular matrix (ECM) and promote anisotropic fiber orientation, two mechanical signals generated through a Snail1/RhoA/alpha SMA-dependent mechanism that sustains oriented tumor cell migration and invasiveness. Snail1-depleted CAF failed to acquire myofibroblastic traits in response to TGF Beta, including RhoA activation, alpha-SMA-positive stress fibers, increased fibronectin fibrillogenesis and production of a stiff ECM with oriented fibers. Snail1 expression in human tumor-derived CAF was associated with an ability to organize the ECM. In co-culture, a relatively smaller number of Snail1-expressing CAF were capable of imposing an anisotropic ECM architecture, compared to non-activated fibroblasts.
Pathologically, human breast cancers with Snail1+ CAF tended to exhibit desmoplastic areas with anisotropic fibers, lymph node involvement and poorer outcomes. Snail1 involvement in driving an ordered ECM was further confirmed in wound healing experiments in mice, with Snail1 depletion preventing the anisotropic organization of granulation tissue and delaying wound healing. Overall, our results showed that inhibiting Snail1 function in CAF could prevent tumor-driven ECM reorganization and cancer invasion.

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm associated with asbestos exposure. Although previous studies based on candidate gene approaches have identified important common somatic mutations in MPM, these studies have focused on small sets of genes and have provided a limited view of the genetic alterations underlying this disease. Here, we performed whole-exome sequencing on DNA from 22 MPMs and matched blood samples, and identified 517 somatic mutations across 490 mutated genes. Integrative analysis of mutations and somatic copy-number alterations revealed frequent genetic alterations in BAP1, NF2, CDKN2A, and CUL1. Our study presents the first unbiased view of the genomic basis of MPM. Cancer Res; 1–6. ©2014 AACR.

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm associated with asbestos exposure. Although previous studies based on candidate gene approaches have identified important common somatic mutations in MPM, these studies have focused on small sets of genes and have provided a limited view of the genetic alterations underlying this disease. Here, we performed whole exome sequencing on DNA from 22 MPMs and matched blood samples, and identified 517 somatic mutations across 490 mutated genes. Integrative analysis of mutations and somatic copy number alterations (SCNAs) revealed frequent genetic alterations in BAP1, NF2, CDKN2A, and CUL1. Our study presents the first unbiased view of the genomic basis of MPM.

Anaplastic thyroid cancer (ATC) is one of the most lethal human malignancies, but its genetic drivers remain little understood. In this study, we report losses in expression of the miRNA miR30a, which is downregulated in ATC compared with differentiated thyroid cancer and normal tissue. miR30a downregulation was associated with advanced differentiated thyroid cancer and higher mortality. Mechanistically, we found miR30a decreased cellular invasion and migration, epithelial–mesenchymal transition marker levels, lysyl oxidase (LOX) expression, and metastatic capacity. LOX was identified as a direct target of miR30a that was overexpressed in ATC and associated with advanced differentiated thyroid cancer and higher mortality rate. Consistent with its role in other cancers, we found that LOX inhibited cell proliferation, cellular invasion, and migration and metastasis in vitro and in vivo. Together, our findings establish a critical functional role for miR30a downregulation in mediating LOX upregulation and thyroid cancer progression, with implications for LOX targeting as a rational therapeutic strategy in ATC. Cancer Res; 75(2); 1–11. ©2014 AACR.

Immune rejection of tumors is mediated by IFNγ production and T-cell cytolytic activity. These processes are impeded by PD-1, a coinhibitory molecule expressed on T cells that is elevated in tumor-infiltrating lymphocytes (TIL). PD-1 elevation may reflect T-cell exhaustion marked by decreased proliferation, production of type I cytokines, and poor cytolytic activity. Although anti–PD-1 antibodies enhance IFNγ secretion after stimulation of the T-cell receptor (TCR), the mechanistic link between PD-1 and its effects on T-cell help (Tc1/Th1 skewing) remains unclear. In prospectively collected cancer tissues, we found that TIL exhibited dampened Tc1/Th1 skewing and activation compared with peripheral blood lymphocytes (PBL). When PD-1 bound its ligand PD-L1, we observed a marked suppression of critical TCR target genes and Th1 cytokines. Conversely, PD-1 blockade reversed these suppressive effects of PD-1:PD-L1 ligation. We also found that the TCR-regulated phosphatase SHP-2 was expressed higher in TIL than in PBL, tightly correlating with PD-1 expression and negative regulation of TCR target genes. Overall, these results defined a PD-1/SHP-2/STAT1/T-bet signaling axis mediating the suppressive effects of PD-1 on Th1 immunity at tumor sites. Our findings argue that PD-1 or SHP-2 blockade will be sufficient to restore robust Th1 immunity and T-cell activation and thereby reverse immunosuppression in the tumor microenvironment. Cancer Res; 75(3); 1–11. ©2014 AACR.