Transforming Growth Factor-β Limits Secretion of Lumican by Activated Stellate Cells within Primary Pancreatic Adenocarcinoma Tumors

Abstract

Purpose Pancreatic ductal adenocarcinoma (PDAC) is lethal cancer whose primary tumor is characterized by dense composition of cancer cells, stromal cells and extracellular matrix (ECM) composed largely of collagen. Within the PDAC tumor microenvironment, activated pancreatic stellate cells (PSC) are the dominant stromal cell type and responsible for collagen deposition. Lumican is a secreted proteoglycan that regulates collagen fibril assembly. We have previously identified that the presence of lumican in the ECM surrounding PDAC cells is associated with improved patient outcome after multimodal therapy and surgical removal of localized PDAC. Experimental Design Lumican expression in PDAC from 27 patients was determined by IHC and quantitatively analyzed for co-localization with PSC. In vitro studies examined the molecular mechanisms of lumican transcription and secretion from PSC (HPSC, HPaSteC), and cell adhesion and migration assays examined the effect of lumican on PSC in a collagen-rich environment. Results Here we identify PSC as a significant source of extracellular lumican production through quantitative IHC analysis. We demonstrate that the cytokine, transforming growth factor-β (TGF-β), negatively regulates lumican gene transcription within HPSC through its canonical signaling pathway and binding of SMAD4 to novel SBEs identified within the promoter region. Additionally, we found that the ability of HPSC to produce and secrete extracellular lumican significantly enhances HPSC adhesion and mobility on collagen. Conclusion Our results demonstrate that activated pancreatic stellate cells within PDAC secrete lumican under the negative control of TGF-β; once secreted, the extracellular lumican enhances stellate cell adhesion and mobility in a collagen rich environment.

Hypoxia-induced autophagy of stellate cells inhibits expression and secretion of lumican into microenvironment of pancreatic ductal adenocarcinoma

“…As illustrated in Fig. 1a, positive HIF1α staining was seen in the stroma and the epithelial compartments, suggesting hypoxic conditions within the TME; lumican protein was primarily located in stromal compartment, a finding consistent with our previous studies which showed that activated pancreatic stellate cells in the tumor are a principal source of stromal lumican [14,15]. Importantly, lumican and HIF1α expression were observed within the same microscopic regions within tumor stromal compartment, suggesting lumican expression and secretion occurs within hypoxic regions of the TME.…”

“…A growing body of literature has identified lumican as an inhibitor of multiple hallmarks Edited by G. Del Sal characteristics of cancer biology including: cancer cell proliferation, invasion and metastasis as well as tumor growth promoting inflammation and angiogenesis [8][9][10][11][12][13]. Our laboratory has observed that activated pancreatic stellate cells within the tumor microenvironment (TME) are a principal source of stromal lumican [14,15], and mounting evidence suggests lumican is also a key regulator of ECM and ECM-cell interactions within the TME [16].…”

Prolonged exposure to extracellular lumican restrains pancreatic adenocarcinoma growth

“…2,4 Our recent work demonstrated that activated pancreatic stellate cells within the tumour are a principle source of stromal lumican and the presence of lumican within the stroma of primary PDAC tumours is associated with decreased metastasis and prolonged survival. 10,13 Based on these results, we investigated whether the absence of host lumican would influence PDAC growth (Figure 1a, upper-right). Using a syngeneic orthotopic pancreatic tumour model, we compared growth of PanO2 cells within the pancreas of wild-type C57B6 mice versus those with loss of one or both copies of the LUM gene.…”

Preclinical Evaluation of Sequential Combination of Oncolytic Adenovirus Delta-24-RGD and Phosphatidylserine-Targeting Antibody in Pancreatic Ductal Adenocarcinoma

“…Paraffin embedded tumor tissues were cut into 5 µm sections. Immunohistochemistry or immunofluorescence staining was performed using the methods described previously (18). Images were captured with an Olympus DP72 camera and CellSens software (Center Valley, PA) on an Olympus BX51 microscope.…”