Upregulation of matrix metalloproteinase MMP-14 (MT1-MMP) is associated with poor prognosis in cancer patients, but it is unclear how MMP-14 becomes elevated in tumors. Here we show that miR-181a-5p is downregulated in aggressive human breast and colon cancers where its levels correlate inversely with MMP-14 expression. In clinical specimens, enhanced expression of MMP-14 was observed in cancer cells located at the invasive front of tumors where miR-181a-5p was downregulated relative to adjacent normal cells. Bioinformatics analyses defined a potential miR-181a-5p response element within the 3′ untranslated region (UTR) of MMP-14 that was validated in reporter gene experiments. Ectopic miR-181a-5p reduced MMP-14 expression, whereas miR-181a-5p attenuation elevated MMP-14 expression. In support of a critical relationship between these two genes, miR-181a-5p-mediated reduction of MMP-14 levels was sufficient to decrease cancer cell migration, invasion and activation of pro-MMP-2. Further, this reduction in MMP-14 levels was sufficient to reduce in vivo invasion and angiogenesis in chick chorioallantoic membrane assays. Taken together, our results establish the regulation of MMP-14 in cancers by miR-181a-5p through a post-transcriptional mechanism, and they further suggest strategies to elevate miR-181a-5p to prevent cancer metastasis.

TNF plays a dual, still enigmatic role in melanoma, either acting as a cytotoxic cytokine or favoring a tumorigenic inflammatory microenvironment. Herein, the tumor growth of melanoma cell lines expressing major histocompatibility complex class I molecules at high levels (MHC-Ihigh) was dramatically impaired in TNF-deficient mice, and this was associated with enhanced tumor-infiltrating CD8+ T lymphocytes. Immunodepletion of CD8 T cells fully restored melanoma growth in TNF−/− mice. Systemic administration of Etanercept inhibited MHC-Ihigh melanoma growth in immunocompetent but not in immunodeficient (IFNγ−/−, nude, or CD8−/−) mice. MHC-Ihigh melanoma growth was also reduced in mice lacking TNF-R1, but not TNF-R2. TNF−/− and TNF-R1−/− mice as well as Etanercept-treated WT mice displayed enhanced intratumor content of high endothelial venules surrounded by high CD8+ T-cell density. Adoptive transfer of activated TNF-R1–deficient or –proficient CD8+ T cells in CD8-deficient mice bearing B16K1 tumors demonstrated that TNF-R1 deficiency facilitates the accumulation of live CD8+ T cells into the tumors. Moreover, in vitro experiments indicated that TNF triggered activated CD8+ T cell death in a TNF-R1–dependent manner, likely limiting the accumulation of tumor-infiltrating CD8+ T cells in TNF/TNF-R1–proficient animals. Collectively, our observations indicate that TNF-R1–dependent TNF signaling impairs tumor-infiltrating CD8+ T-cell accumulation and may serve as a putative target to favor CD8+ T-cell–dependent immune response in melanoma. Cancer Res; 75(13); 1–10. ©2015 AACR.

Tumor Necrosis Factor α (TNF) plays a dual, still enigmatic role in melanoma, either acting as a cytotoxic cytokine or favoring a tumorigenic inflammatory microenvironment. Herein, the tumor growth of melanoma cell lines expressing major histocompatibility complex class I molecules at high levels (MHC-Ihigh) was dramatically impaired in TNF-deficient mice and this was associated with enhanced tumor-infiltrating CD8+ T lymphocytes. Immunodepletion of CD8 T cells fully restored melanoma growth in TNF-/- mice. Systemic administration of Etanercept inhibited MHC-Ihigh melanoma growth in immunocompetent but not in immunodeficient (IFNγ-/-, nude or CD8-/-) mice. MHC-Ihigh melanoma growth was also reduced in mice lacking TNF-R1, but not TNF-R2. TNF-/- and TNF-R1-/- mice as well as Etanercept-treated WT mice displayed enhanced intra-tumor content of high endothelial venules (HEV) surrounded by high CD8+ T cell density. Adoptive transfer of activated TNF-R1-deficient or proficient CD8+ T cells in CD8-deficient mice bearing B16K1 tumors demonstrated that TNF-R1 deficiency facilitates the accumulation of live CD8+ T cells into the tumors. Moreover, in vitro experiments indicated that TNF triggered activated CD8+ T cell death in a TNF-R1-dependent manner, likely limiting the accumulation of tumor-infiltrating CD8+ T cells in TNF/TNF-R1-proficient animals. Collectively, our observations indicate that TNF-R1-dependent TNF signaling impairs tumor-infiltrating CD8+ T cell accumulation and may serve as a putative target to favor CD8+ T cell-dependent immune response in melanoma.

Pancreatic cancer, one of the most lethal forms of human cancer, is largely resistant to many conventional chemotherapeutic agents. Although many therapeutic approaches focus on tumor growth, metastasis is a primary factor contributing to lethality. Therefore, novel therapies to target metastatic invasion could prevent tumor spread and recurrence resulting from local and distant metastasis. The protein Vav1 is aberrantly expressed in more than half of pancreatic cancers. Its expression promotes activation of Rac and Cdc42 and leads to enhanced invasion and migration, as well as increased tumor cell survival and proliferation, suggesting that Vav1 could be a potent therapeutic target for pancreatic cancer. The purine analogue azathioprine, well known for its function as an anti-inflammatory compound, was recently shown to function by inhibiting Vav1 signaling in immune cells. We therefore hypothesized that azathioprine could also inhibit Vav1 in pancreatic tumor cells to reduce its proinvasive functions. Indeed, we have found that treatment of cultured pancreatic tumor cells with azathioprine inhibited Vav1-dependent invasive cell migration and matrix degradation, through inhibition of Rac and Cdc42 signaling. Furthermore, azathioprine treatment decreased metastasis in both xenograft and genetic mouse models of pancreatic cancer. Strikingly, metastasis was dramatically reduced in Vav1-expressing tumors arising from p48Cre/+, KrasG12D/+, p53F/+ mice. These inhibitory effects were mediated through Vav1, as Vav1-negative cell lines and tumors were largely resistant to azathioprine treatment. These findings demonstrate that azathioprine and related compounds could be potent antimetastatic agents for Vav1-positive pancreatic tumors. Cancer Res; 75(14); 1–9. ©2015 AACR.

TMPRSS2 gene rearrangements occur at DNA breaks formed during androgen receptor–mediated transcription and activate expression of ETS transcription factors at the early stages of more than half of prostate cancers. NKX3.1, a prostate tumor suppressor that accelerates the DNA repair response, binds to androgen receptor at the ERG gene breakpoint and inhibits both the juxtaposition of the TMPRSS2 and ERG gene loci and also their recombination. NKX3.1 acts by accelerating DNA repair after androgen-induced transcriptional activation. NKX3.1 influences the recruitment of proteins that promote homology-directed DNA repair. Loss of NKX3.1 favors recruitment to the ERG gene breakpoint of proteins that promote error-prone nonhomologous end-joining. Analysis of prostate cancer tissues showed that the presence of a TMPRSS2–ERG rearrangement was highly correlated with lower levels of NKX3.1 expression consistent with the role of NKX3.1 as a suppressor of the pathogenic gene rearrangement. Cancer Res; 75(13); 1–13. ©2015 AACR.