Is Development Of Hepatocellular Carcinoma Driven By Liver Homing Signals?

There are a limited number of models to study hepatocellular carcinoma (HCC). Hepa 1-6 cell line can be used to develop tumors when injected directly in the liver of C57/BL6 mice. We isolated cells from a tumor which developed in the liver following the intrasplenic injection of Hepa 1-6 cells and found that the daughter cells led to more systematic development of tumors. Studies were performed to test the characteristics of the 2 cell lines. In vivo tumorigenicity was assessed by injecting cells in the spleen. Minimal cell dose and liver specificity were assessed at 28 days. Tumors (≥0,5mm) were counted and alpha-fetoprotein (AFP) mRNA measured by relative RT-PCR. Cell lines were compared in vitro for their alpha-1 integrin (ITGa1), beta1-integrin (ITGb1), AFP and Epithelial Cell Adhesion Molecule (EpCAM) mRNA expression. Apoptosis was measured following exposure to cisplatinum [25µg/ml]. Invasiveness and motility were assessed using a modified wound healing assay and a double layered COL1 hemisphere invasion assay. Cell doubling time (CDT) was measured by cell count. Intrahepatic tumours developed more quickly (21d vs. 70d) and more often (66% (4/6) vs. 15% (1/7)) with the daughter cell line. Tumors first appeared 21 days after intrasplenic injection and increased steadily thereafter: this was associated with increased AFP expression in liver homogenates. The minimal cell concentration required to give raise to visible tumors was 10K with the daughter cell line while no tumor was observed at 28d with the parental cell line (1M cells). No extra hepatic tumours were found at any point and with any cell concentration. However, subcutaneous injection induced hepatic tumours in every animal only when using the more tumorigenic daughter cell line (100% 3/3 at 28d). In vitro, the daughter cell line showed increased resistance to apoptosis when exposed to COL1, did not show increase proliferation, but were less motile and less invasive. Cell doubling time was longer with the daughter cell line then with the parental one (45.5h±2.7h vs 34.6h±0.4h; p Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4426. doi:1538-7445.AM2012-4426