Boylan, Khrista

Poly(GP) proteins are a promising pharmacodynamic marker for developing and testing therapeutics for treating C9ORF72 -associated amyotrophic lateral sclerosis.

Targeting three defects with one strategy The neurodegenerative diseases amyotrophic lateral sclerosis and frontotemporal dementia are most commonly caused by a mutation in the C9orf72 gene. The mutation is an expanded hexanucleotide repeat in a noncoding region. The expanded repeat produces sense and antisense RNA transcripts, which accumulate in patient cells and appear to sequester RNA-binding proteins. The sense and antisense transcripts are also translated into dipeptide repeat proteins, which are aggregation-prone and accumulate in the brain and spinal cord. Last, loss of function from reduced expression of C9orf72 in neurons and glia could contribute to the disease. Kramer et al. targeted both sense and antisense repeats by blocking a single gene called SPT4 , which mitigated degeneration in human cells by reducing all three types of pathologies. Science , this issue p. 708

A mouse model for ALS A G4C2 repeat expansion in C9ORF72 is known to be the major genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis (c9FTD/ALS). However, a lack of animal models recapitulating key disease features has hindered efforts to understand and prevent c9FTD/ALS-related neurodegeneration. Until now. Chew et al. describe a mouse model that mimics both neuropathological and clinical phenotypes of c9FTD/ALS. Science , this issue p. 1151

Abstract 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. In this study, the cell adhesion molecule, Nectin-4, was investigated as a potential mediator of several steps involved in ovarian cancer progression. In particular, due to the ability of Nectin-4 to promote cell-cell adhesions, we were interested in determining its role in mediating the formation of cell-cell aggregates (spheroids) which are commonly seen in the peritoneal fluid of ovarian cancer patients. Furthermore, since spheroids are known to have a decreased rate of cell proliferation and are chemoresistant, we were also interested in the role of Nectin-4 in ovarian cancer cell proliferation and invasion. In our previous studies, we performed gene microarray analysis and identified Nectin-4 overexpression in ovarian cancer tissues compared to normal ovaries and other normal tissues. By ELISA, we found soluble Nectin-4 in the sera of 50% of women with ovarian cancer. In this study, we performed a series of experiments in which two human ovarian cancer cells lines were transfected with Nectin-4 or shRNA targeting Nectin-4, and then the resultant cells were tested in functional assays. In the first case, MA148 cells, which do not express Nectin-4, were transfected with full-length Nectin-4. The resultant MA148 cells which expressed high levels of Nectin-4 showed an increased rate of proliferation compared to control cells which did not express Nectin-4. They also formed the initial cell-cell adhesions involved in spheroid formation faster than control cells. Furthermore, the spheroids which expressed Nectin-4 were slower to disaggregate and invade through monolayers of mesothelial cells. In the second case, NIH:OVCAR5 cells, which express moderate levels of Nectin-4, were transfected with shRNA targeting Nectin-4, resulting in the partial knockdown of Nectin-4 expression. We found that the NIH:OVCAR5 cells that express lower levels of Nectin-4 on their surface required a substantially longer time to form spheroids and migrated more slowly in a wound healing assay. In both cases, we verified the expression of Nectin-4 in the transfected cells by Western immunoblotting and flow cytometry. These results suggest that Nectin-4: (a) is important in the early events of cell-cell adhesion, (b) plays a role in multicellular aggregation within the ascites of ovarian cancer patients, and (c) causes tight spheroid formations that may impede disaggregation. 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. Citation Format: Kristin L. Boylan, Adam Meyer, Petra C. Buchanan, Melissa S. DeRycke, Amy P. Skubitz. Role of nectin-4 in the progression of ovarian cancer. [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 1984. doi:10.1158/1538-7445.AM2014-1984