Description: Chronic inflammation drives liver cancer pathogenesis, invasion, and metastasis. Liver Kupffer cells have crucial roles in mediating the inflammatory processes that promote liver cancer, but the mechanistic basis for their contributions are not fully understood. Here we show that expression of the proinflammatory myeloid cell surface receptor TREM-1 expressed by Kupffer cells is a crucial factor in the development and progression of liver cancer. Deletion of the murine homolog Trem1 in mice attenuated hepatocellular carcinogenesis triggered by diethylnitrosamine (DEN). Trem1 deficiency attenuated Kupffer cell activation by downregulating transcription and protein expression of interleukin (IL)-6, IL-1β, TNF, CCL2, and CXCL10. In addition, Trem1 ablation diminished activation of the p38, extracellular regulated kinase 1/2, JNK, mitogen-activated protein kinase, and NF-κB signaling pathways in Kupffer cells, resulting in diminished liver injury after DEN exposure. Adoptive transfer of wild-type Kupffer cells to Trem1-deficient mice complemented these defects and reversed unresponsiveness to DEN-induced liver injury and malignant development. Together, our findings offer causal evidence that TREM-1 is a pivotal determinant of Kupffer cell activation in liver carcinogenesis, deepening mechanistic insights into how chronic inflammation underpins the development and progression of liver cancer. Cancer Res; 72(16); 3977–86. ©2012 AACR.

Description: Purpose: We previously showed that targeting Delta-like ligand 4 (DLL4) in colon and breast tumors inhibited tumor growth and reduced tumor initiating cell frequency. In this report, we have extended these studies to pancreatic cancer and probed the mechanism of action in tumor and stromal cells involved in antitumor efficacy. Experimental Design: Patient-derived pancreatic xenograft tumor models were used to evaluate the antitumor effect of anti-DLL4. To investigate the mechanism of action, we compared the activity of targeting DLL4 in tumor cells with an anti-human DLL4 antibody (anti-hDLL4) and in the host stroma/vasculature with an anti-mouse DLL4 antibody (anti-mDLL4). The effect of these antibodies on cancer stem cell frequency was examined by in vivo limiting dilution assays. Results: The combination of anti-hDLL4 and anti-mDLL4 was efficacious in a broad spectrum of pancreatic tumor xenografts and showed additive antitumor activity together with gemcitabine. Treatment with either anti-hDLL4 or anti-mDLL4 delayed pancreatic tumor recurrence following termination of gemcitabine treatment, and the two together produced an additive effect. Anti-hDLL4 had a pronounced effect in reducing the tumorigenicity of pancreatic cancer cells based on serial transplantation and tumorsphere assays. In contrast, disruption of tumor angiogenesis with anti-mDLL4 alone or with anti-VEGF had minimal effects on tumorigenicity. Gene expression analyses indicated that anti-DLL4 treatment regulated genes that participate in Notch signaling, pancreatic differentiation, and epithelial-to-mesenchymal transition. Conclusions: Our findings suggest a novel therapeutic approach for pancreatic cancer treatment through antagonism of DLL4/Notch signaling. Clin Cancer Res; 18(19); 5374–86. ©2012 AACR .

Description: Angiogenesis is a major clinical feature of esophageal squamous cell carcinoma (ESCC), an aggressive disease of increasing incidence in developed countries. In ESCCs, the proangiogenic factor VEGF-C is an independent prognostic factor for ESCC, where understanding the mechanisms of VEGF-C upregulation may cue possible therapeutic insights. Here, we report that expression of the transcription factor Nkx2-8 is downregulated in ESCCs where it inversely correlates with progression and VEGF-C upregulation. Patients with ESCCs with lower Nkx2-8 expression exhibited reduced overall survival. Modulating expression of Nkx2-8 up or down inhibited or enhanced, respectively, proangiogenic activity in vitro and in vivo. Mechanistic investigations showed that Nkx2-8 repressed NF-κB activity by restraining nuclear localization of NF-κB p65 via downregulation of AKIP1, a NF-κB p65 binding partner, and also by directly targeting the AKIP1 promoter. We confirmed evidence for the importance of the Nkx2-8/AKIP1/NF-κB axis identified in ESCC cell models through an immunohistochemical analysis of a large cohort of human ESCC specimens. Taken together, our results showed that Nkx2-8 functions as a tumor suppressor in ESCCs, the downregulation of which contributes to NF-κB activation and ESCC angiogenesis. Cancer Res; 73(12); 3638–48. ©2013 AACR.

Description: Purpose: miR-452 is reported to be required for neural crest stem cell differentiation during neural crest development. However, the biologic role of miR-452 in gliomas remains unclear. The aim of the present study was to evaluate the effect of miR-452 on the stem-like properties and tumorigenesis of glioma cells. Experimental Design: The expression of miR-452 was examined in glioma cells and glioma tissues using real-time PCR. The effects of miR-452 on stem-like traits and tumorigenesis were investigated in vitro and in vivo using patient-derived glioma cells and glioma cell lines. Western blotting and luciferase reporter assays were conducted to examine the negative regulation of Bmi-1, LEF1, and TCF4 by miR-452. The methylation of the miR-452 promoter region was examined by bisulfite genomic sequencing PCR. Results: miR-452 was markedly downregulated in glioma cells and clinical glioma tissues. miR-452 levels were inversely correlated with World Health Organization (WHO) grades and patient survival. miR-452 directly targeted and suppressed multiple stemness regulators, including Bmi-1, LEF1, and TCF4, resulting in reduced stem-like traits and tumorigenesis of glioma cells in vitro and in vivo . Furthermore, we showed that downregulation of miR-452 in gliomas was caused by hypermethylation of its promoter region. Conclusions: Downregulation of miR-452 plays an important role in promoting the stem-like traits and tumorigenesis of gliomas and may represent a novel prognostic biomarker and therapeutic target for the disease. Clin Cancer Res; 19(13); 3429–38. ©2013 AACR .

Description: Metastasis, the leading cause of cancer death, requires tumor cell intravasation, migration through the bloodstream, arrest within capillaries, and extravasation to invade distant tissues. Few mechanistic details have been reported thus far regarding the extravasation process or re-entry of circulating tumor cells at metastatic sites. Here, we show that neuropilin-2 (NRP-2), a multifunctional nonkinase receptor for semaphorins, vascular endothelial growth factor (VEGF), and other growth factors, expressed on cancer cells interacts with α5 integrin on endothelial cells to mediate vascular extravasation and metastasis in zebrafish and murine xenograft models of clear cell renal cell carcinoma (RCC) and pancreatic adenocarcinoma. In tissue from patients with RCC, NRP-2 expression is positively correlated with tumor grade and is highest in metastatic tumors. In a prospectively acquired cohort of patients with pancreatic cancer, high NRP-2 expression cosegregated with poor prognosis. Through biochemical approaches as well as Atomic Force Microscopy (AFM), we describe a unique mechanism through which NRP-2 expressed on cancer cells interacts with α5 integrin on endothelial cells to mediate vascular adhesion and extravasation. Taken together, our studies reveal a clinically significant role of NRP-2 in cancer cell extravasation and promotion of metastasis. Cancer Res; 73(14); 4579–90. ©2013 AACR.

Description: Inflammatory stimuli clearly contribute to lung cancer development and progression, but the underlying pathogenic mechanisms are not fully understood. We found that the proinflammatory cytokine IL-1β is dramatically elevated in the serum of patients with non–small cell lung cancer (NSCLC). In vitro studies showed that IL-1β promoted the proliferation and migration of NSCLC cells. Mechanistically, IL-1β acted through the COX2–HIF1α pathway to repress the expression of microRNA-101 (miR-101), a microRNA with an established role in tumor suppression. Lin28B was identified as critical effector target of miR-101 with its repression of Lin28B, a critical aspect of tumor suppression. Overall, IL-1β upregulated Lin28B by downregulating miR-101. Interestingly, cyclooxygenase-2 inhibition by aspirin or celecoxib abrogated IL-1β-mediated repression of miR-101 and IL-1β-mediated activation of Lin28B along with their stimulatory effects on NSCLC cell proliferation and migration. Together, our findings defined an IL-1β–miR-101–Lin28B pathway as a novel regulatory axis of pathogenic inflammatory signaling in NSCLC. Cancer Res; 74(17); 4720–30. ©2014 AACR.

Description: Myeloid-derived suppressor cells (MDSC) contribute significantly to the malignant characters conferred by hypoxic tumor microenvironments. However, selective biomarkers of MDSC function in this critical setting have not been defined. Here, we report that miR-210 expression is elevated by hypoxia-inducible factor-1α (HIF1α) in MDSC localized to tumors, compared with splenic MDSC from tumor-bearing mice. In tumor MDSC, we determined that HIF1α was bound directly to a transcriptionally active hypoxia-response element in the miR-210 proximal promoter. miR-210 overexpression was sufficient to enhance MDSC-mediated T-cell suppression under normoxic conditions, while targeting hypoxia-induced miR-210 was sufficient to decrease MDSC function against T cells. Mechanistic investigations revealed that miR-210 modulated MDSC function by increasing arginase activity and nitric oxide production, without affecting reactive oxygen species, IL6, or IL10 production or expression of PD-L1. In splenic MDSC, miR-210 regulated Arg1, Cxcl12, and IL16 at the levels of both mRNA and protein, the reversal of which under normoxic conditions decreased T-cell–suppressive effects and IFNγ production. Interestingly, miR-210 overexpression or targeting IL16 or CXCL12 enhanced the immunosuppressive activity of MDSC in vivo, resulting in increased tumor growth. Taken together, these results provide a preclinical rationale to explore miR-210 inhibitory oligonucleotides as adjuvants to boost immunotherapeutic responses in cancer patients. Cancer Res; 75(18); 3771–87. ©2015 AACR.

Description: Purpose: STAT3 is known to have both oncogenic and tumor suppressive effects, but the regulation of these opposing effects is elusive. We hypothesized that STAT3β, one of the two STAT3 isoforms, is the key determinant in this context. Experimental Design: The prognostic significance of STAT3β and phospho-STAT3α Y705 (pSTAT3α Y705 ) was evaluated in 286 cases of patients with esophageal squamous cell carcinoma (ESCC). STAT3β-induced changes in the chemosensitivity to cisplatin and 5-fluorouracil were assessed both in vitro and in vivo . STAT3β-induced changes in the frequency of cancer stem cells were evaluated using Hoechst and CD44 staining. How STAT3β regulates STAT3α was determined using immunoprecipitation, confocal microscopy, DNA-binding, and chromatin immunoprecipitation-PCR. Results: STAT3β expression is an independent protective prognostic marker in patients with ESCC, which strongly correlated with longer overall survival ( P = 0.0009) and recurrence-free survival ( P = 0.0001). STAT3β significantly decreased the cancer stem cell population, and sensitized ESCC cells to cisplatin and 5-fluorouracil in tumor xenografts. Mechanistically, STAT3β markedly attenuated the transcription activity of STAT3α via inducing STAT3α:STAT3β heterodimers. However, the heterodimer formation decreased the binding between STAT3α and PTPN9 (better known as PTP-MEG2), a protein tyrosine phosphatase, thereby promoting the phosphorylation of STAT3α Y705 and enhancing its nuclear translocation and DNA binding. Correlating with this, high STAT3β expression converts the prognostic value of pSTAT3α Y705 from unfavorable to favorable in patients with ESCC. Conclusions: STAT3β suppresses chemoresistance and cancer stemness by blocking the transcriptional activity of STAT3α. The paradoxical increase in pSTAT3α Y705 induced by STAT3β carries important implications as to how the biologic and prognostic significance of STAT3 in cancers should be interpreted. Clin Cancer Res; 22(3); 691–703. ©2015 AACR .

Description: Traditional approaches to evaluating antitumor agents using human tumor xenograft models have generally used cohorts of 8 to 10 mice against a limited panel of tumor models. An alternative approach is to use fewer animals per tumor line, allowing a greater number of models that capture greater molecular/genetic heterogeneity of the cancer type. We retrospectively analyzed 67 agents evaluated by the Pediatric Preclinical Testing Program to determine whether a single mouse, chosen randomly from each group of a study, predicted the median response for groups of mice using 83 xenograft models. The individual tumor response from a randomly chosen mouse was compared with the group median response using established response criteria. A total of 2,134 comparisons were made. The single tumor response accurately predicted the group median response in 1,604 comparisons (75.16%). The mean tumor response correct prediction rate for 1,000 single mouse random samples was 78.09%. Models had a range for correct prediction (60%–87.5%). Allowing for misprediction of ± one response category, the overall mean correct single mouse prediction rate was 95.28%, and predicted overall objective response rates for group data in 66 of 67 drug studies. For molecularly targeted agents, occasional exceptional responder models were identified and the activity of that agent confirmed in additional models with the same genotype. Assuming that large treatment effects are targeted, this alternate experimental design has similar predictive value as traditional approaches, allowing for far greater numbers of models to be used that more fully encompass the heterogeneity of disease types. Cancer Res; 76(19); 5798–809. ©2016 AACR.

Description: The intermediate filament protein Nestin serves as a biomarker for stem cells and has been used to identify subsets of cancer stem–like cells. However, the mechanistic contributions of Nestin to cancer pathogenesis are not understood. Here, we report that Nestin binds the hedgehog pathway transcription factor Gli3 to mediate the development of medulloblastomas of the hedgehog subtype. In a mouse model system, Nestin levels increased progressively during medulloblastoma formation, resulting in enhanced tumor growth. Conversely, loss of Nestin dramatically inhibited proliferation and promoted differentiation. Mechanistic investigations revealed that the tumor-promoting effects of Nestin were mediated by binding to Gli3, a zinc finger transcription factor that negatively regulates hedgehog signaling. Nestin binding to Gli3 blocked Gli3 phosphorylation and its subsequent proteolytic processing, thereby abrogating its ability to negatively regulate the hedgehog pathway. Our findings show how Nestin drives hedgehog pathway–driven cancers and uncover in Gli3 a therapeutic target to treat these malignancies. Cancer Res; 76(18); 5573–83. ©2016 AACR.