Pulmonary metastasis in xenograft model after orthotopic implantation

Metastasis is a major factor for mortality in patients with hepatocellular carcinoma (HCC). Thus, there is a need for predictive biomarker(s) for detecting the tipping point before metastasis, so as to prevent further deterioration. To discover early warning signals of pulmonary metastasis in HCC, we analysed time-series gene expression data in the spontaneous pulmonary metastasis mouse HCCLM3-RFP model with our novel dynamic network biomarker (DNB) method. To simulate tumour growth and metastasis in patient livers, we used the spontaneous pulmonary metastasis mouse model, HCCLM3-RFP, which involves the orthotopic transplanted human HCCLM3 cell line labelled with a stable fluorescent protein.We observed that, hepatic tumours in orthotopic xenograft HCCLM3-RFP mice grew gradually from the second to the fifth week after orthotopic implantation in the primary liver tissue, whereas spontaneous pulmonary metastasis occurredonly at the last time point (the fifth week after orthotopic implantation).Thus, we chose the second, third, fourth, and fifth weeks after orthotopic implantation as observation points to collect liver tumours of five orthotopic xenograft mice at each time point and to assess the whole-genome expression. In total, 20 nude mice that underwent orthotopic tumour implantation, were divided into four groups. After the orthotopic tumour implantation, one group of mice were sacrificed each at the second, third, fourth, and fifth weeks for autopsy.