Abstract 1548: Re-isolated metastatic pancreatic cancer cells show distinct modulation of gene expression during liver colonization
Authors: Al-Taee Khamael M K , Berger Martin R. , Adwan Hassan 
Published: July 2016

Gastrointestinal cancers typically metastasize into the liver. By re-isolation of pancreatic ductal adenocarcinoma (PDAC) cells from the liver of rats harboring these cells in their liver we assessed gene expression during various stages and investigated whether extracellular matrix (ECM) genes play a role in metastatic pancreatic cancer cells. We used ASML rat pancreatic cancer cells, which were inoculated into the portal vein of isogenic BDX rats. These cells had been marked by eGFP, which allowed their re-isolation following liver perfusion by FACS sorting after early (1,3 days), intermediate (9 days), advanced (16 days), and terminal (21 days) stages of liver metastasis. Re-isolated ASML cells were used for total RNA isolation and subsequently their gene expression was investigated by Illumina chip array for mRNA and miRNA species, followed by Ingenuity pathway analysis (IPA).

Pending on the time span following re-isolation, 7-15% of all known genes and 10% of miRNA species were modulated significantly in expression. By IPA analysis, significant alterations in diseases, disorders and canonical pathways were found. Interestingly, cancer was ranked second within the five top diseases and disorders at early and terminal stages, and third at intermediate and advanced stages. Within the cancer category, the gene groups related to metastasis and advanced malignant tumor were most significantly altered, but found decreased at early and advanced stages, and increased at the terminal stage only. In addition, ECM genes were modulated significantly. These genes included gene families as chemokines, transforming growth factor -beta (TGF-β), laminins, A Disintegrin and Metalloproteinase (ADAM) peptidases, matrix metallopeptidases (MMPs), collagens, and others. From all 59 chemokines investigated, 18 and 11 mRNAs were significantly up- and down regulated. Similarly, from 21 MMPs, 6 and 2 mRNAs were significantly up and down modulated. Finally, from 39 collagens, 16 and 7 were significantly up and down regulated in expression. Also, the respective miRNAs species were modulated: In case of collagens, the miR-29b-3p species was significantly down modulated (2-fold) in accord with the upregulation of respective target collagens. Also, the miRNA species regulating chemokines were altered as shown e.g. for CCR5, which was more than 10 fold increased at mRNA level with the corresponding miR-125b-5p being ca. 2 fold decreased.

In conclusion, among the top five modulated diseases and disorders,

cancer ranked only at intermediate positions. In addition, the expression profiles of ECM genes were altered significantly in metastatic pancreatic cancer cells and thus hypothetically contributed to successful colonization of the liver by these cells.

Citation Format: Khamael M K Al-Taee, Martin R. Berger, Hassan Adwan. Re-isolated metastatic pancreatic cancer cells show distinct modulation of gene expression during liver colonization. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1548.