PDAC-cells Differentially Modulate Expression of Neutrophil Serine Proteases and Their Inhibitors

Pro-inflammatory tumors are a defining feature of pancreatic cancer. Infiltrating leukocytes modulate inflammation and aid in PDAC disease progression; this leads them to be therapeutic targets for researchers. Neutrophils, which are pro-tumorigenic, are the most abundant leukocyte in circulation; although past research has indicated that neutrophils aid in tumor progression, the mechanisms behind tumor-associated neutrophils are relatively unknown. One focus of my laboratory is neutrophil serine proteases (NSP), enzymes produced by neutrophils capable of inducing apoptosis. The inhibitors of these NSPs are serine protease inhibitors (serpins), and past research has shown that deficiencies in them have led to high cell mortality, indicating that these serpins and NSPs may modulate apoptosis levels (4). My lab has also shown that neutrophil survival increases with the treatment of PDAC-conditioned media. The specific objective of my project is to understand how PDAC cells modulate the expression of neutrophil serine proteases and their inhibitors. We used cDNA from a mouse promyelocyte neutrophil cell line (MPRO) that was treated with different PDAC-conditioned media. Expression levels of NSP genes (Cathepsin G (CatG), Neutrophil Elastase (NE), and Proteinase 3 (PR3)) and their inhibitors (Serpin b1a, Serpin b6a, and Serpin a1a) were observed using qRT-PCR (1). We observed that for NSPs, the trend indicated greater expression in the gemcitabine-resistant treated cell lines (CD18/HPAF GemR and T3M4 GemR), compared to the parental treated cell lines (CD18/HPAF and T3M4). Additionally, for L3.3 (low metastatic) and L3.6 (high metastatic) treated neutrophils, we see upregulation expression of serine proteases in L3.6 treated cells compared to L3.3 treated cells. In contrast, for NSP inhibitors, the trend indicates greater expression in the parental cell lines than in gemcitabine-resistant cell lines. There is upregulation in both L3.3 and L3.6 cell expression as well. Together, our data suggests that PDAC cells differentially modulate the expression of NSPs and their inhibitors.