Effect of human umbilical cord blood derived CD34+ hematopoietic stem cell on the expression of Wnt4 and P53 genes in a rat model of hepatocellular carcinoma

BACKGROUND AND AIM OF THE WORK: Hepatocellular carcinoma (HCC) is the most frequent primary liver malignancy. Chronic liver injuries as chronic hepatitis C and hepatitis B viruses, aflatoxins consumption and nonalcoholic fatty liver disease are well-established causes of HCC. HCC is associated with a series of molecular changes, as alternation in glypican-3, P53 expression and Wnt/β-catenin pathway. Hepatic cancer progenitor cells could contribute to HCC development. This research aimed to study the effectiveness of human CD34+ hematopoietic stem cell on Wnt4 and P53 genes expression, histopathological grading and hepatic progenitor cells percentage in HCC rat model.

MATERIALS AND METHODS: HCC was induced in the experimental group of outbred Sprague Dawley rats by administration of 50 mg/L N-nitroso-Di-Ethylamine (DEN) in drinking water for 15 weeks. Forty-six animals were used in total, they were initially subdivided into two groups; control (n = 6) and experimental (n = 40), the latter consisting of 4 DEN-unaffected, 6 DEN-lethalities and 30 surviving DEN-animals with elevated AFP. These 30 animals with elevated AFP were then subdivided into a new HCC control group (n = 15) and the stem cell treated group (n = 15). The latter group was injected with CD34+ human hematopoietic stem cell (1 × 106 cells/rat) in the rat's tail vein. Cyclosporine A (10 mg/kg) was injected intraperitoneal, starting 24 h before human stem cell transplantation. After 20 weeks passing since the beginning of the experiment, all rats were sacrificed and liver specimens were subjected to histopathological examination, RT-PCR in order to examine Wnt4 and P53 gene expression and flow cytometry to measure hepatic progenitor OV6 positive cells percentage.

RESULTS: The saline-treated HCC group (with prior 15 week DEN exposure) showed higher levels of wnt4 and p53 gene expression (1.59 and 1.36 fold, respectively) and increased percentage in OV6+ progenitor cells (+4.9% in absolute terms) compared to saline-treated controls (p < 0.01, ANOVA). Compared with the saline HCC-group, transplantation with CD34+ human hematopoietic stem cells produced a further increase in the levels of wnt4 (+19.4%) and p53 gene expression (+53%), a 2-fold increase in the percentage of cancer progenitor cells and increased HCC pathology grading (all p < 0.01). The positive correlation between p53 and HCC grade (Spearman rho +0.73, p < 0.05) and negative correlation between wnt and OV6+% levels (rho -0.65, p < 0.05) in the saline-HCC group were not observed in the CD34+ HCC group.

CONCLUSIONS: Human CD34+ cells transplantation has a deteriorating effect on HCC.