Lung cancer remains the leading cause of cancer mortality in men and women in the U.S. and worldwide. About 90% of lung cancer cases are caused by smoking and the use of tobacco products. However, other factors such as radon gas, asbestos, air pollution exposures, and chronic infections can contribute to lung carcinogenesis. In addition, multiple inherited and acquired mechanisms of susceptibility to lung cancer have been proposed. Lung cancer is divided into two broad histologic classes, which grow and spread differently: small-cell lung carcinomas (SCLC) and non-small cell lung carcinomas (NSCLC). Treatment options for lung cancer include surgery, radiation therapy, chemotherapy, and targeted therapy. Therapeutic-modalities recommendations depend on several factors, including the type and stage of cancer. Despite the improvements in diagnosis and therapy made during the past 25 years, the prognosis for patients with lung cancer is still unsatisfactory. The responses to current standard therapies are poor except for the most localized cancers. However, a better understanding of the biology pertinent to these challenging malignancies, might lead to the development of more efficacious and perhaps more specific drugs. The purpose of this review is to summarize the recent developments in lung cancer biology and its therapeutic strategies, and discuss the latest treatment advances including therapies currently under clinical investigation.

We previously showed that the cell adhesion molecule Nectin-4 is overexpressed in ovarian cancer tumors, and its cleaved extracellular domain can be detected in the serum of ovarian cancer patients. The ADAM (isintegrin ndetalloproteinase) proteases are involved in ectodomain cleavage of transmembrane proteins, and ADAM17 is known to cleave Nectin-4 in breast cancer. However, the mechanism of Nectin-4 cleavage in ovarian cancer has not yet been determined. Analysis of ovarian cancer gene microarray data showed that higher expression of Nectin-4, ADAM10, and ADAM17 is associated with significantly decreased progression-free survival. We quantified Nectin-4 shedding from the surface of ovarian cancer cells after stimulation with lysophosphatidic acid. We report that ADAM17 and ADAM10 cleave Nectin-4 and release soluble Nectin-4 (sN4). Small molecule inhibitors and siRNA knockdown of both ADAM proteases confirmed these results. In matched samples from 11 high-grade serous ovarian cancer patients, we detected 2-20-fold more sN4 in ascites fluid than serum. Co-incubation of ovarian cancer cells with ascites fluid significantly increased sN4 shedding, which could be blocked using a dual inhibitor of ADAM10 and ADAM17. Furthermore, we detected RNA for Nectin-4, ADAM10, and ADAM17 in primary ovarian carcinoma tumors, secondary omental metastases, and ascites cells isolated from serous ovarian cancer patients. In a signaling pathway screen, lysophosphatidic acid increased phosphorylation of AKT, EGF receptor, ERK1/2, JNK1/2/3, and c-Jun. Understanding the function of Nectin-4 shedding in ovarian cancer progression is critical to facilitate its development as both a serum biomarker and a therapeutic target for ovarian cancer.

The cell adhesion molecule Nectin-4 is overexpressed in epithelial cancers, including ovarian cancer. The objective of this study was to determine the biological significance of Nectin-4 in the adhesion, aggregation, migration, and proliferation of ovarian cancer cells. Nectin-4 and its binding partner Nectin-1 were detected in patients’ primary tumors, omental metastases, and ascites cells. The human cell lines NIH:OVCAR5 and CAOV3 were genetically modified to alter Nectin-4 expression. Cells that overexpressed Nectin-4 adhered to Nectin-1 in a concentration and time-dependent manner, and adhesion was inhibited by antibodies to Nectin-4 and Nectin-1, as well as synthetic Nectin peptides. In functional assays, CAOV3 cells with Nectin-4 knock-down were unable to form spheroids and migrated more slowly than CAOV3 parental cells expressing Nectin-4. NIH:OVCAR5 parental cells proliferated more rapidly, migrated faster, and formed larger spheroids than either the Nectin-4 knock-down or over-expressing cells. Parental cell lines expressed higher levels of epithelial markers and lower levels of mesenchymal markers compared to Nectin-4 knock-down cells, suggesting a role for Nectin-4 in epithelial-mesenchymal transition. Our results demonstrate that Nectin-4 promotes cell-cell adhesion, migration, and proliferation. Understanding the biology of Nectin-4 in ovarian cancer progression is critical to facilitate its development as a novel therapeutic target.

AimsLung cancer is one of the most deadly cancers; median survival from diagnosis is less than one year in those with advanced disease. Novel lung cancer biomarkers are desperately needed. In this study, we evaluated SULF2 expression by immunohistochemistry and its association with overall survival in a cohort of patients with non-small cell lung cancer (NSCLC). We also looked for the presence of SULF2 protein in plasma to evaluate its potential as an early detection biomarker for NSCLC.MethodsWe identified patients who underwent surgical resection for pulmonary adenocarcinoma or squamous cell carcinoma at our institution. A section from each paraffin-embedded specimen was stained with a SULF2 antibody. A pathologist determined the percentage and intensity of tumor cell staining. Survival analysis was performed using a multivariate Cox proportional hazards model. Using a novel SULF2 ELISA assay, we analyzed plasma levels of SULF2 in a small cohort of healthy donors and patients with early stage NSCLC.ResultsSULF2 staining was present in 82% of the lung cancer samples. Squamous cell carcinomas had a higher mean percentage of staining than adenocarcinomas (100% vs. 60%; p<0.0005). After adjusting for age, sex, race, histologic type, stage, and neoadjuvant therapy, there was a non-significant (31%; p = 0.65) increase in the risk of death for patients with adenocarcinoma with SULF2 staining in tumor cells. In contrast, there was a significant decrease in the risk of death (89%; p = 0.02) for patients with squamous cell carcinoma with SULF2 staining in tumor cells. SULF2 protein was present in plasma of patients with early stage NSCLC, and soluble SULF2 levels increased with age. Finally, plasma SULF2 levels were significantly elevated in early stage NSCLC patients, compared to healthy controls.ConclusionsTumor expression of SULF2 may affect prognosis in NSCLC, while blood SULF2 levels may have a significant role in the diagnosis of this fatal disease.

Purpose of the Study: The mechanisms by which ovarian cancer cells are released from the primary tumor, seed throughout the peritoneal cavity, attach to local organs, and then invade these organs, are not understood. A unique aspect of ovarian cancer progression is the collection of ascites fluid in the abdominal cavity, which contains free-floating tumor cells in the form of single cells and multicellular aggregates. In previous studies, we showed that the cell adhesion molecule Nectin-4 is highly expressed in ovarian cancer tumors, whereas its expression in normal tissues is limited; making Nectin-4 an attractive target for therapy. Nectins are a family of four cell adhesion molecules that are important in the formation and maintenance of cell junctions. Other studies have suggested that the extracellular domain of Nectins can be proteolytically cleaved by the A Disintegrin And Metalloprotease 17 (ADAM17) to release a soluble fragment. We hypothesize that this cleavage step may be important in regulating Nectin function and increases the likelihood of cancer dissemination. We have shown that the soluble fragment of Nectin-4 (sN4) is detected in the sera of 50% of ovarian cancer patients, but is not detected in the sera of women with benign gynecological conditions. The purpose of this study was to determine how Nectin-4 is cleaved from the surface of ovarian cancer cells and the role that Nectin-4 plays in the aggregation, migration, and proliferation of ovarian cancer cells. Experimental Procedures: In the first series of experiments, NIH:OVCAR5, a human ovarian cancer cell line that expresses moderate levels of Nectin-4, was transfected with shRNA targeting Nectin-4, resulting in the partial knockdown of Nectin-4 expression. The cells were then tested in several functional assays. In the second series of experiments, NIH:OVCAR5 cells were transfected with full length Nectin-4 and the level of sN4 in the spent media in the presence of various inhibitors of metalloproteases was quantified by ELISA and Western blotting. We also tested these cells for their rate of proliferation. Summary of Data: NIH:OVCAR5 cells that expressed low levels of Nectin-4 required a substantially longer time to form multicellular aggregates, migrate, and proliferate. NIH:OVCAR5 cells that expressed high levels of Nectin-4 shed sN4 following 3 hours of stimulation with phorbol myristate acetate (PMA). A broad spectrum inhibitor of matrix metalloproteases (MMPs) and ADAMs completely inhibited Nectin-4 shedding, while inhibitors of ADAM17 and/or ADAM10 inhibited Nectin-4 shedding by 30-100%. NIH:OVCAR5 cells that expressed high levels of Nectin-4 proliferated more rapidly than the parental cell line. Conclusions: This study suggests that Nectin-4 promotes cell-cell adhesion (important in the formation of multicellular aggregates), yet it can be cleaved from the surface of cells to allow cells to disaggregate (important in invasion). Additional functional studies leading to a better understanding of the role of Nectin-4 overexpression and shedding in ovarian cancer are currently underway. Understanding the role of Nectin-4 in ovarian cancer progression is critical in order to facilitate its development as a novel therapeutic target for ovarian cancer. This project was funded by the Minnesota Ovarian Cancer Alliance. Citation Format: Kristin L.M. Boylan, Petra C. Buchanan, Adam Meyer, Bruce Walcheck, Amy P.N. Skubitz. Cleavage of the cell adhesion molecule nectin-4 from the surface of ovarian cancer cells: a mechanism for cancer progression and a novel serum biomarker [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-BIOL-1304.