In the Feburary 5th issue of Cancer Cell, Chinese scientists from the University of Hong Kong, Z. F. Yang et al., published the results of their study on the role of CD90+ cells in hepatocellular carcinoma (HCC) cell lines, tumor specimens, and blood samples. The investigators found that CD90+ cancer stem cells from HCC cell lines had tumorigenic capabilities. The study results revealed that the malignant cells with CD90+CD45- phenotype, which had been isolated from primary tumors (100%) and 91.6% from blood samples could generate tumors when implanted into immunodeficient mice. It was also found that cell isolates with the CD90+CD44+ phenotype formed more aggressive tumors and metastatic lesions in the immunodeficient mice than cells withCD90+CD44-. By blocking the CD44 epitope, the cancer stem cells lost their ability to form metastatic nodules in the lungs of the mice. (It should be noted that M. Romero-Ramos et al. reported (J. Neuroscience Res 69:894-907 [2002]) pluripotent stem cells from rat muscle tissues express the CD90 surface marker)

Scientists from The Hong Kong University, Z. F. Yange et al., reported in the February issue of Cancer Cell the results of their study in characterizing cancer stem cells in human liver cancers. The investigators found that cells from hepatocellular carcinoma cell line, tumor specimens and blood samples that were tumorgenic expressed the surface marker CD90. It also found that in blood samples from liver cancer patients a subpopulation of CD45-CD90+ were able to generate tumors in immunodeficient mice. The investigators also discovered that cancer cells with the CD90+CD44+ phenotype produce tumors that were highly invasive and formed metastatic lesions in SCID mice. With CD44 blockaded, the cancer stem cells loss their ability to form these highly invasive tumors in the SCID mice. The authors concluded that cancer stem cells in human liver cancers expressed the CD90 surface marker.