(A-39) In Vitro Approach to Interrogate Confinement in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for about 90% of all pancreatic cancer cases and 5-year survival rates have remained below 12% since the 1970’s, in part due to the difficulty in detection prior to metastasis (migration and invasion into neighboring organs and glands). Cancerous PDAC tissue is correlated with increased elastic modulus (E ≈ 10 kPa) compared with healthy tissue (E ≈ 1 kPa). Mechanical memory is a concept that has emerged over the past decade that may provide a path towards understanding how invading PDAC cells “remember” the mechanical properties of their original (stiff) microenvironment even whilst in contact with a softer environment. Here, we investigated the role of mechanical memory by culturing a dilute suspension of PDAC (MIA PaCa-2) cells within a 3D microgel platform with tunable mechanical and rheological properties. We conducted a suite of acute (short- term) priming studies where we cultured PDAC cells in either a soft (E ≈ 1 kPa) or stiff (E ≈ 10 kPa) environment for 6 h, then removed cells and placed them into a new soft or stiff 3D environment for another 18 h. Following these steps, we conducted RNA-seq analyses to quantify the gene expression profiles. Initial priming in 3D culture showed some persistent gene expression for the duration of the study, regardless of the subsequent environments (stiff or soft). Stiff 3D culture was associated with the down-regulation of tumor suppressors (LATS1, BCAR3, CDKN2C), as well as several other cancer-associated genes. Stiff-primed genes were stratified against patient data found in The Cancer Genome Atlas (TCGA). Upregulated genes in stiff-primed 3D culture were associated with decreased survival in patient data, suggesting a link between patient survival and mechanical memory.