The role of MMP3 and Rac1b during development and progression of pancreatic cancer
Chronic pancreatitis is a major risk factor for pancreatic ductal adenocarcinoma (PDAC), one of the deadliest cancer types. During the progression to cancer the inflammatory-harmed tissue undergoes formations such as acinar to ductal metaplasia (ADM), pancreatic intraepithelial neoplasia (PanIN) and...
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|Chronic pancreatitis is a major risk factor for pancreatic ductal adenocarcinoma (PDAC), one of the deadliest cancer types. During the progression to cancer the inflammatory-harmed tissue undergoes formations such as acinar to ductal metaplasia (ADM), pancreatic intraepithelial neoplasia (PanIN) and epithelial mesenchymal transition (EMT). Previously it has been shown that MMP3 and Rac1b play important roles during the progression of lung and mammary cancer and transition in different cell lines. To investigate whether MMP3 and Rac1b have an influence on the development and progression of pancreatic cancer, different cell lines for in vitro and two triple transgenic mouse models (rtTA-Ela1/tet-HA-MMP3/tet-KRAs and rtTA-Ela1/tet-YFP-Rac1b/tet-KRas) for in vivo experiments were examined. The in vitro results were achieved by comparing different cell lines to the amount of endogenous MMP3 and Rac1b and the growth behavior. S2-007, an invasive and epithelial cell line, and MiaPaCa, a more mesenchymal behaving cell line, were the most promising ones and used for further investigations. To examine the effects on EMT, the cells were treated with recombinant protein or adenoviral constructs to overexpress MMP3 and Rac1b and screened for EMT marker proteins by RT-qPCR. The results show an influence of MMP3 and Rac1b on EMT machinery mainly in S2-007 cells and less in MiaPaCa cells. In the same way, a higher migration potential in S2-007 cells after MMP3 overexpression was found by using a wound healing assay performed. The infection with adenoviral constructs showed different effects on EMT marker expression compared to the ectopic expression with recombinant proteins. Additionally, both kinds of treatment resulted in higher Rac1b, E-cadherin, and Vimentin expression levels on Plastic than on Matrigel.
For in vivo experiments mice were treated for 5 months either with NaCl or Caerulein to induce chronic pancreatitis. The transgene was activated by using a reverse tetracycline-dependent promotor. The expectation that KRas on the background of chronic pancreatitis drives forward the tissue alterations to pancreatic cancer could not be confirmed, but ADM was found, what is one of the pre-stages of PDAC.
All these findings suggested that MMP3 and Rac1b seem not to influence the EMT machinery in pancreatic tissue as much as expected, especially under in vivo conditions. Here additional pathways, such as TGFβ or NFκB signaling, seem to prefer Rac1b as interaction partner to promote EMT.