Determine Changes to Nascent ECM on Therapy Resistant Cells — 72p — Kyle Schubert^1,2, Kristin Calar¹, Pilar de la Puente^1,3

¹ Cancer Biology and Immunotherapies Group, Sanford Research, Sioux Falls, SD, USA. 

² Sanford Program for Undergraduate Research (SPUR), Sanford Research, Sioux Falls, SD, USA.

³ Department of Surgery, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, USA

Ovarian carcinoma (OC) is one of the deadliest forms of cancer in women, with 80% of patients developing resistance to treatment within 5 years. This chemoresistance in OC has been associated with the dysregulation of the tumor extracellular matrix (ECM) composition and structure. The effects of ECM composition and structure on therapeutic response have been well explored, but the bidirectional effects of ECM changes associated with chemotherapy is relatively uncharted. Our goal is to track ECM dynamics of newly synthesized ECM (nascent ECM) in response to treatment. An OC cell line (SKOV3) was either not exposed (naïve) or exposed to 3 (therapy resistant cycle 3, TR-C3) or 6 cycles (therapy resistant cycle 6, TR-C6) of on-off cisplatin treatment mimicking clinical patient treatment. Naïve, TR-C3, and and TR-C6 cells were incubated with cancer-associated fibroblasts (CAFs) and co-cultured for 7 days in the absence or presence of additional cisplatin treatment (1.75 uM) in a 3D hybrid hydrogel matrix. Using metabolic labeling with azidohomoalanine (AHA), newly deposited nascent ECM protein was tracked by super resolution confocal imaging and quantified with Arivis Pro software. Nascent ECM was identified to be increased in terms of intensity, volume, and distance upon cisplatin treatment in naïve cells and exacerbated overtime compared to controls. Nascent ECM secretion was increased in TR-C3 and TR-C6 compared to naïve in untreated conditions, highlighting the effects of continuous cisplatin treatment on ECM secretion. However, TR-C3 and TR-C6 cells did not have changes in sensitivity compared to naïve cells. Our studies suggest that chemotherapy itself induces nascent ECM secretion. Future studies would include proteomics analysis of the nascent ECM to identify specific ECM proteins. These studies could shed light onto novel markers that may restrict chemotherapy-induced ECM remodeling and further combat the development of chemoresistance.

Sanford Research
Pilar de la Puente