Liver metastasis of pancreatic cancer: the hepatic microenvironment impacts differentiation and self-renewal capacity of pancreatic ductal epithelial cells

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is often diagnosed at advanced stages with the liver as the main site of metastases. The hepatic microenvironment has been shown to determine outgrowth of liver metastases. Cancer stem cells (CSCs) are essential for initiation and maintenance of tumors and acquisition of CSC-properties has been linked to Epithelial-Mesenchymal-Transition. Thus, this study aimed at elucidating whether and how the hepatic microenvironment impacts stemness and differentiation of disseminated pancreatic ductal epithelial cells (PDECs). Culture of premalignant H6c7-kras and malignant Panc1 PDECs together with hepatocytes and hepatic stellate cells (HSC) promoted self-renewal capacity of both PDEC lines. This was indicated by higher colony formation compared to cells cocultured with hepatocytes and hepatic myofibroblasts. Different Panc1 colony types derived from an HSC-enriched coculture were expanded and characterized revealing that holoclones exhibited an enhanced colony formation ability, elevated and exclusive expression of the CSC-marker Nestin and a more pronounced mesenchymal phenotype compared to paraclones. Moreover, Panc1 holoclone cells showed an increased tumorigenic potential in vivo leading to formation of undifferentiated tumors in 7/10 animals, while inoculation of paraclone cells only led to formation of tumors in 2/10 animals being smaller in number and size. Holoclone tumors were characterized by elevated expression of mesenchymal markers, complete loss of E-cadherin expression and high expression of Nestin. Finally, Etanercept-mediated TNF-α blocking partly reversed the mesenchymal CSC-phenotype of Panc1 holoclone cells. Overall, these data provide evidence that the hepatic microenvironment determines stemness and differentiation of PDECs, thereby substantially contributing to liver metastases of PDAC.

A Phase Ib Study of Single-Agent Idelalisib Followed by Idelalisib in Combination with Chemotherapy in Patients with Metastatic Pancreatic Ductal Adenocarcinoma

“…In comparison with previous studies, AST and ALT values were elevated, whereas diarrhea and colitis were lower or not observed [11,12,19]. The observed AST and ALT elevations may be due to the nature of mPDAC itself, as most individuals have liver metastasis [20]; however, the small sample size may also have inflated the rate of these TEAEs. Although limited, this study suggests that idelalisib may produce a different safety profile in patients with mPDAC as compared with previous studies of patients with hematologic malignancies.…”

The role of liver microenvironment in hepatic metastasis

“…A specific example involves the migration of pancreatic adenocarcinoma to the liver, in which Knaack et al studied in vitro, manipulating CSCs as well as the microenvironment by incorporating HSCs and hepatic myofibroblasts (HMF) to mimic physiological and inflammatory conditions. The data expressed the importance of HSCs and HMF in the formation of disseminated pancreatic ductal epithelial cell (PDEC) colonies, showing a marked relationship between liver microenvironment and pancreatic CTCs [30]. In addition, these colonies expressed a greater amount of Nestin, a CSC-marker, than their counterparts, which reveals the increased metastatic capabilities of these cells [30].…”

“…The data expressed the importance of HSCs and HMF in the formation of disseminated pancreatic ductal epithelial cell (PDEC) colonies, showing a marked relationship between liver microenvironment and pancreatic CTCs [30]. In addition, these colonies expressed a greater amount of Nestin, a CSC-marker, than their counterparts, which reveals the increased metastatic capabilities of these cells [30].…”

Simulating the human tumor microenvironment in colorectal cancer organoids in vitro and in vivo

“…In the current study we used hepatic stellate cells (LX2) to simulate stromal cells that are involved in collagen remodeling of the liver metastasis microenvironment. [26][27][28][29] The results, demonstrating that LX2mediated ECM structured microarchitecture push the HCT116 metastatic CRC cells towards an epithelial phenotype vs. a mesenchymal phenotype induced by unstructured ECM architecture are especially intriguing as they suggest that under certain conditions the hepatic stellate cells, commonly known to support EMT and growth of liver metastasis 9,30,31 , may act to suppress growth and spreading of metastasis if given an opportunity to create structured matrix around the metastatic foci. Furthermore, HCT116 cells demonstrated reduced chemotherapeutic sensitivity in the LX2 organoids as well.…”