CD44v3 and CD44v6 expression activity in mouse isograft CRC metastatic and liver colonisation system. A. Semi-quantitative CD44v3 and v6 gene expression activity of primary and secondary C26 colon carcinoma isograft tumours implanted orthotopically (colonic) and intrasplenic (liver colonisation model) into Balb/C mice.While in „proper” metastatic system (orthotopic implantation) liver metastases expressed CD44v3/v6 at significantly higher level than colon primaries, in colonisation model liver colonies showed similar expression profile to spleen primaries. B. CD44 v3 and v6 gene expression activity of primary and secondary HT29 human colon carcinoma xenografts in orthotopic and intrasplenic implantation models to scid mice. Selection of CD44v3/v6 high subclone at primary site can be suspected, as liver metastases in orthotopic implantation model system showed higher expression activities than colon primaries. No „clone selection” effect was detected in liver colonisation model (after intrasplenic implantation). C. CD44v3 and v6 gene expression activity of non-metastatic (implanted into adult) and metastatic (implanted into newborn) primary human colon carcinoma xenograft tumours implanted subcutaneously (heterotopicaly) into scid mice. Expression rates are normalized on beta-actin expression rates and non-metastatic v3/v6 expression rates. All three examined human colorectal carcinoma cell types showed higher CD44v3 and CD44v6 expression activities in metastatic system (subcutaneously implanted colon tumours in newborn mice, which developed distant metastases in each animal cases) than in non-metastatic (the same colon carcinomas implanted into adult mice subcuticularly without any single case of distant metastasis formation).