Matthew Rosenow (Presenter)
Translational Genomics Research Institute
Authorship: Matthew Rosenow (1), Sukriti Bagchi (1), Nagar Rajabi (1), Victoria David (1), Hiayong Han (1), Patrick Pirrotte (1)
(1) Translational Genomics Research Institute, Phoenix Arizona
| Short Abstract Poor prognosis in pancreatic cancer has largely been linked to therapeutic resistance to first-line treatments. Tumor heterogeneity in pancreatic adenocarcinoma microenvironment (consisting of fibroblasts, pancreatic stellate cells (PSC), and extracellular matrix proteins (EMPs)) may confer this resistance. Studies have implied that secreted factors targeting tumor growth and metastasis pathways may play an important role in conferring drug resistance as well as the secretion of EMPs that contribute to fibrosis and act by physically limiting drug entry. We carried out a bottom-up mass spectrometry discovery analysis on the secretome to identify secreted factors from PSCs and MiaPaCa—a pancreatic carcinoma cell line—in the presence of the chemotherapeutic drug triptolide. Highly targeted pathways were identified that may provide insight to additional therapeutic strategies or targets. |
Long Abstract
Poor prognosis in pancreatic cancer has been largely linked to therapeutic resistance to first-line treatments. It has been previously reported that tumor heterogeneity in pancreatic adenocarcinoma microenvironment confers this resistance. This complex microenvironment mainly consists of fibroblasts (FBs), pancreatic stellate cells (PSCs), as well as extracellular matrix proteins (EMPs). Although the mechanisms by which stromal cells confer drug resistance is not well characterized, studies have implied that secreted factors targeting tumor growth and metastasis pathways may play an important role, as well as the secretion of EMPs that contribute to fibrosis and act by physically limiting drug entry.
The objective of this study is to elucidate the efficacy of triptolide –a promising chemotherapeutic agent currently being deployed in early clinical trials, as well as to provide insight into possible mechanisms of drug resistance in the presence of this drug. We carried out a bottom-up mass spectrometry discovery analysis to first, identify secreted factors from PSCs and pancreatic carcinoma cells (MIA PaCa-2) in the presence of triptolide, and second, to determine what influence secreted factors from stromal cells have on MIA PaCa-2 cells. This comprehensive characterization of the pancreatic tumor microenvironment may then expose additional therapeutic strategies or targets in the context of pancreatic cancer treatment.
The first part of this project was carried out comparing the proteins of the secretome and the cellular proteome of both the pancreatic stellate cells and MIA PaCa-2 cells grown in culture in the absence and presence of triptolide. This revealed the differential effects of triptolide on each cell type with respect to both secreted proteins and cellular proteins. Results show that triptolide has a unique effect on each cell type, and pathway analysis was performed on those proteins that showed a greater than two-fold differential change. For the stellate cells, pathways involving the extracellular matrix proteins and fibrosis were highly targeted, suggesting that triptolide reduces fibrosis. The pathway analysis also suggests that triptolide works on MIA PaCa-2 cells primarily by affecting metabolic pathways—an effect not seen in the stellate cells.
Then, to determine what influence secreted factors from stromal cells have on cancer cells, MIA PaCa-2 cells were cultured in conditioned media from stellate cells that were grown in triptolide treated and untreated conditions. The MIA PaCa-2 cells were collected and the cellular protein component was analyzed to potentially reveal pathways directly affected by factors secreted by these stellate cells. Results from pathway analysis show metabolic pathways involving oxidative phosphorylation, glycolysis/gluconeogenesis, and CFTR (cystic fibrosis transmembrane conductance regulator) are highly represented in the MIA PaCa-2 cells exposed to conditioned media.
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