Side population of pancreatic cancer cells predominates in TGF‐β‐mediated epithelial to mesenchymal transition and invasion

Abstract

We report here side population (SP) cells, a cancer stem cell enriched fraction from pancreatic cancer cell line, have enormous superior potential of the epithelial to mesenchymal transition (EMT), invasion, and metastasis. In an isolated SP cell culture, the cells rapidly expressed and up-regulated E-cadherin, an epithelial phenotypic marker, and the cells formed tightly contacted cell cluster, which is a representative epithelial phenotypic appearance. When the SP cells were incubated in the presence of TGF-b, SP cells changed their shape into mesenchymal-like appearance including spindle shaped assembly. This alteration was associated with significant reduction of E-cadherin expression level. TGF-b induced EMT-associated gene alteration such as reduction of Ecadherin mRNA and induction of Snail mRNA and matrixmetalloproteinase (MMP)-2 mRNA. Finally, SP cells exerted notable matrigel invasion activity in response to TGF-b treatment, whereas MP cells did not respond to TGF-b-mediated invasion. In conclusion, these results suggest that SP cells from pancreatic cancer cell line possess superior potentials of phenotypic switch, i.e., EMT/MET, micro-invasion, and in vivo metastasis, as compared to MP cells. Because micro-invasion and metastasis are key mechanisms of cancer malignant potential, SP cells would be the attractive target for preventing cancer progression. ' UICCKey words: TGF-beta; cancer stem cell; invasion; metastasis; E-cadherin Pancreatic cancer is a worldwide health problem with an increasing incidence and poor prognosis. 1 Because of highly metastatic and/or invasive properties of this cancer, the prognosis of the patients with unresectable disease is very poor. For example, the locally advanced disease is observed in 15-20% of pancreatic cancer patients, and associated with a median survival time (MST) of 6 to 10 months. 1,2 In addition, a much higher percentage (40 to 45%) of patients present with metastatic disease, which carries a shorter MST of only 3 to 6 months. 2 Thus, the key to improving the patient survival is to control their local invasion and distant metastasis.Execution of metastasis is composed of multiple processes including cancer cell detachment from the primary tumor, local invasion to disseminate through surrounding blood vessels or lymphatic vessels, and attachment and proliferation at the metastatic site. These processes are at least in part mediated by the phenotypic switch of cancer cells between epithelial phenotype and mesenchymal phenotype, the so-called epithelial to mesenchymal transition (EMT). 3 The EMT is an important process during embryonic development as well as cancer progression. 3 The loss of epithelial characteristics and the acquisition of mesenchymal phenotype lead to enhanced motility and invasive predisposition of cancer cells. The increased migratory activity is mediated by repression of cell to cell adhesion proteins such as E-cadherin, and the induction of invasion-associated integrins and matrix metalloproteinases (MMPs). 4 The cells which obtained...

Excessive Hyaluronan Production Promotes Acquisition of Cancer Stem Cell Signatures through the Coordinated Regulation of Twist and the Transforming Growth Factor β (TGF-β)-Snail Signaling Axis

“…Thus, there was a discrepancy between TGF-␤ and Snail expressions in non-SP cells. It is likely that SP cells are more responsive to TGF-␤, based on an earlier report that the TGF-␤ response is greater in SP than non-SP cells (35). TGF-␤ is secreted by most cells as a biologically inactive complex, termed a large latent TGF-␤ complex and stored in the ECM.…”

Multiple uses of basement membrane‐like matrix (BME/Matrigel) in vitro and in vivo with cancer cells

“…It has also been used to study cancer stem/progenitor cell invasion. 28 In addition, the assay has been used in various ways beyond just measuring the invasive activity of cancer cells (Table 3). The invasion chamber is used to select for the invasive cell subpopulations (the cells that are highly invasive) vs the non invasive cells (cells that remain on top of the BME on the filter).…”

Transforming growth factor β-induced epithelial-mesenchymal transition increases cancer stem-like cells in the PANC-1 cell line

“…EMT is characterized by the loss of epithelial characteristics and the acquisition of a mesenchymal phenotype, which increases the invasion and migration activity of cancer cells (10)(11)(12)(13)(14). Growth factors, such as transforming growth factor β (TGF-β) and epidermal growth factor, are currently used to induce EMT (15,16).…”