Total HLA Class I Antigen Loss with the Downregulation of Antigen-Processing Machinery Components in Two Newly Established Sarcomatoid Hepatocellular Carcinoma Cell Lines.

Limited information is currently available concerning HLA class I antigen abnormalities in sarcomatoid hepatocellular carcinoma (sHCC). Here, we have analyzed the growth characteristics and HLA class I antigen status of four sHCC cell lines (sHCC29, sHCC63, sHCC74, and SAR-HCV); the first three were newly established in this study. Among the four, sHCC29 showed the highest growth rate in vitro and tumorigenicity in NOD-SCID mice. Unlike sHCC74 and SAR-HCV, both sHCC29 and sHCC63 had no detectable surface HLA class I antigen expression, alongside undetected intracellular ß 2-microglobulin (ß 2m) and marked HLA class I heavy chain and selective antigen-processing machinery (APM) component downregulation. The loss of ß 2m in sHCC29 and sHCC63 was caused by a >49 kb deletion across the B2M locus, while their downregulation of APM components was transcriptional, reversible by IFN-γ only in several components. ß 2m was also undetected in the primary HCC lesions of the patients involved, indicating its in vivo relevance. We report for the first time HLA class I antigen loss with underlying B2M gene deficiency and APM defects in 50% (2 of 4) of the sHCC cell lines tested. These findings may have implications for a proper design of T cell immunotherapy for the treatment of sHCC patients.

Differential expression of CD44 and CD24 markers discriminates the epitheliod from the fibroblastoid subset in a sarcomatoid renal carcinoma cell line: evidence suggesting the existence of cancer stem cells in both subsets as studied with sorted cells.

Epithelioid and fibroblastoid subsets coexist in the human sarcomatoid renal cell carcinoma (sRCC) cell line, RCC52, according to previous clonal studies. Herein, using monoclonal antibodies to CD44 and CD24 markers, we identified and isolated these two populations, and showed that CD44bright/CD24dim and CD44bright/CD24bright phenotypes correspond to epithelioid and fibroblastoid subsets, respectively. Both sorted subsets displayed different levels of tumorigenicity in xenotransplantation, indicating that each harbored its own cancer stem cells (CSCs). The CD44bright/CD24bright subset, associated with higher expression of MMP-7, -8 and TIMP-1 transcripts, showed greater migratory/invasive potential than the CD44bright/CD24dim subset, which was associated with higher expression of MMP-2, -9 and TIMP-2 transcripts. Both subsets differentially expressed stemness gene products c-Myc, Oct4A, Notch1, Notch2 and Notch3, and the RCC stem cell marker, CD105 in 4-5% of RCC52 cells. These results suggest the presence of CSCs in both sRCC subsets for the first time and should therefore be considered potential therapeutic targets for this aggressive malignancy.