Citations

Circulating tumor cells (CTCs) in blood are associated with poor survival of patients with breast, prostate, or colon cancer. We hypothesized that CTCs are associated with poor survival of patients with cholangiocarcinoma (CCA). Eighty‐eight patients with CCA were prospectively enrolled at Mayo Clinic Rochester between June 2010 and September 2014. The CellSearch system by Veridex was used for detection of CTCs in peripheral blood. Associations between CTC, patient and tumor characteristics, and survival were examined using the Cox's proportional hazards model. Fifteen patients (17%) were positive for CTC ≥2 and 8 patients (9%) for CTC ≥5. CTCs were associated with tumor extent. CTC ≥2 (hazard ratio [HR]: 2.5; 95% confidence interval [CI]: 1.1‐5.4; P = 0.02) and CTC ≥5 (HR, 4.1; 95% CI: 1.4‐10.8; P = 0.01) were both independent predictors of survival. In subgroup analyses, CTC ≥2 (HR, 8.2; 95% CI: 1.8‐57.5; P < 0.01) and CTC ≥5 (HR, 7.7; 95% CI: 1.4‐42.9; P = 0.02) were both associated with shorter survival among patients with metastasis. There was a trend toward association of CTC ≥5 with shorter survival in patients with nonmetastatic CCA (HR, 4.3; 95% CI: 1.0‐13.8; P = 0.06). CTC ≥2 (HR, 10.5; 95% CI: 2.2‐40.1; P < 0.01) and CTC ≥5 (HR, 10.2; 95% CI: 1.5‐42.3; P = 0.02) were both associated with shorter survival among patients with perihilar/distal CCA. CTC ≥5 was associated with shorter survival of patients with intrahepatic CCA (HR, 4.2; 95% CI: 1.1‐14.1; P = 0.04). Conclusion: CTCs were associated with more‐aggressive tumor characteristics and independently associated with survival in patients with CCA. Assessment of CTCs may be useful for identifying CCA patients at risk of early mortality. (Hepatology 2016;63:148–158)

Abstract Targeting membrane PD-1 molecules expressed by tumor-reactive T cells is gaining acceptance as a potentially effective anti-tumor immunotherapy. PD-1 blockade mediated by monoclonal antibodies has yielded promising therapeutic effects in treatment of melanoma, lung cancer and kidney cancers. Although detecting PD-1 expression by T cells is relatively straightforward, a simple and reliable method for determining whether PD-1 on T cells has engaged its ligand B7-H1 (PD-L1) is wanting. Our previous studies have revealed that engagement of PD-1 or B7-1 by B7-H1 results in alternations of apoptosis signaling pathway by up-regulating pro-apoptotic molecules among activated T cells and are correlated with B7-H1-mediated T cell death. Those observations suggest that intracellular levels of apoptosis-related Bcl2 family molecules among PD-1 positive CD8 T cells may be barometers of the extent to which PD-1 has been triggered by B7-H1. Using PD-1 and B7-H1 deficient animal models, we found that lower levels of intracellular pro-apoptosis molecules identify those activated T cells whose PD-1 molecules have not yet been extensively engaged, thus T cell function might be restored to their normal function once PD-1 signals from B7-H1 are blocked. Similarly, human PD-1 positive CD8 T cells engaged by B7-H1 also expressed higher levels of pro-apoptosis molecules during antigen stimulation. Our clinical data demonstrated that pro-apoptosis molecule expression by tumor-reactive T cell levels are higher among advanced melanoma and prostate cancers than healthy controls, reflecting chronic engagement with B7-H1. Thus, using pro-apoptosis status as signaling biomarkers for T cell PD-1 engagement, it may be possible to select patients who are most likely to have strong benefit from PD-1 or B7-H1 (PD-L1) blockade therapy. Citation Format: Wei Zhao, Haidong Dong. T cell apoptosis signaling biomarker of PD-1 engagement in cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2552. doi:10.1158/1538-7445.AM2014-2552

Abstract Development of resistance to chemotherapy and immunotherapy is a major obstacle in extending the survival of cancer patients. Although several molecular mechanisms have been identified that can contribute to chemoresistance, the role of immune checkpoint molecules in tumor chemoresistance has received little consideration. Elevated expression of B7-H1 (also named PD-L1) is predictive of an aggressive disease course, including increases in disease progression and cancer-related mortality in a variety of cancers (ovary, breast, liver, pancreas, esophagus, colon and lung). Although the aggressiveness of B7-H1 positive tumors has been attributed to B7-H1's immune-suppressive function, B7-H1 itself may be directly altering tumor cell intracellular signaling pathways promoting acquisition of drug resistance. It has been reported that overexpression of B7-H1 confers chemoresistance in human cancers. However, the mechanisms by which B7-H1 contributes to tumor chemoresistance have yet to be defined. We show that B7-H1 transfected tumor cells are resistant to chemotherapy. This resistance is due to increased activation of MAPK/ERK pathway in tumor cells with B7-H1 overexpression. Inhibition of ERK activation restored drug sensitivity of B7-H1 positive tumor cells. We further analyzed the downstream elements of B7-H1 signaling pathway and identified a new B7-H1 associated protein that is involved in DNA damage repair and MAPK/ERK activation mechanisms. We conclude that B7-H1 mediates tumor chemoresistance by enhancing the activation of MAPK/ERK pathway via its intracellular signaling pathway. Our studies may identify a novel pharmaceutical target for treatment of B7-H1 positive refractory tumor cells. Citation Format: Amanda Orzechowski, Haidong Dong. B7-H1 confers tumor chemoresistance by regulating MAPK/ERK activation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5026. doi:10.1158/1538-7445.AM2014-5026

Multiple pulmonary conditions are characterized by an abnormal misbalance between various tissue components, for example, an increase in the fibrous connective tissue and loss/increase in extracellular matrix proteins (ECM). Such tissue remodeling may adversely impact physiological function of airway smooth muscle cells (ASMCs) responsible for contraction of airways and release of a variety of bioactive molecules. However, few efforts have been made to understand the potentially significant impact of tissue remodeling on ASMCs. Therefore, this study reports how ASMCs respond to a change in mechanical stiffness of a matrix, to which ASMCs adhere because mechanical stiffness of the remodeled airways is often different from the physiological stiffness. Accordingly, using atomic force microscopy (AFM) measurements, we found that the elastic modulus of the mouse bronchus has an arithmetic mean of 23.1 ± 14 kPa (SD) (median 18.6 kPa). By culturing ASMCs on collagen-conjugated polyacrylamide hydrogels with controlled elastic moduli, we found that gels designed to be softer than average airway tissue significantly increased cellular secretion of vascular endothelial growth factor (VEGF). Conversely, gels stiffer than average airways stimulated cell proliferation, while reducing VEGF secretion and agonist-induced calcium responses of ASMCs. These dependencies of cellular activities on elastic modulus of the gel were correlated with changes in the expression of integrin-β1 and integrin-linked kinase (ILK). Overall, the results of this study demonstrate that changes in matrix mechanics alter cell proliferation, calcium signaling, and proangiogenic functions in ASMCs.

Abstract We investigated the influence of PD-1 expression on the systemic antitumor response (abscopal effect) induced by stereotactic ablative radiotherapy (SABR) in preclinical melanoma and renal cell carcinoma models. We compared the SABR-induced antitumor response in PD-1–expressing wild-type (WT) and PD-1–deficient knockout (KO) mice and found that PD-1 expression compromises the survival of tumor-bearing mice treated with SABR. None of the PD-1 WT mice survived beyond 25 days, whereas 20% of the PD-1 KO mice survived beyond 40 days. Similarly, PD-1–blocking antibody in WT mice was able to recapitulate SABR-induced antitumor responses observed in PD-1 KO mice and led to increased survival. The combination of SABR plus PD-1 blockade induced near complete regression of the irradiated primary tumor (synergistic effect), as opposed to SABR alone or SABR plus control antibody. The combination of SABR plus PD-1 blockade therapy elicited a 66% reduction in size of nonirradiated, secondary tumors outside the SABR radiation field (abscopal effect). The observed abscopal effect was tumor specific and was not dependent on tumor histology or host genetic background. The CD11ahigh CD8+ T-cell phenotype identifies a tumor-reactive population, which was associated in frequency and function with a SABR-induced antitumor immune response in PD-1 KO mice. We conclude that SABR induces an abscopal tumor-specific immune response in both the irradiated and nonirradiated tumors, which is potentiated by PD-1 blockade. The combination of SABR and PD-1 blockade has the potential to translate into a potent immunotherapy strategy in the management of patients with metastatic cancer. Cancer Immunol Res; 3(6); 610–9. ©2015 AACR.

Introduction. We investigated the expression of microRNAs and mRNAs in pleural tissues from patients with either malignant pleural mesothelioma or benign asbestos-related pleural effusion.Methods. Fresh frozen tissues from a total of 18 malignant pleural mesothelioma and 6 benign asbestos-related pleural effusion patients were studied. Expression profiling of mRNA and microRNA was performed using standard protocols.Results. We discovered significant upregulation of multiple microRNAs in malignant pleural mesothelioma compared to benign asbestos-related pleural effusion. Hsa-miR-484, hsa-miR-320, hsa-let-7a, and hsa-miR-125a-5p were able to discriminate malignant from benign disease. Dynamically regulated mRNAs were also identified. MET was the most highly overexpressed gene in malignant pleural mesothelioma compared to benign asbestos-related pleural effusion. Integrated analyses examining microRNA-mRNA interactions suggested multiple altered targets within the Notch signaling pathway.Conclusions. Specific microRNAs and mRNAs may have diagnostic utility in differentiating patients with malignant pleural mesothelioma from benign asbestos-related pleural effusion. These studies may be particularly helpful in patients who reside in a region with a high incidence of mesothelioma.