Cell senescence in myxoid/round cell liposarcoma.

[liposarcoma]

Myxoid /round cell liposarcoma (MLS /RCLS ) is the second most common liposarcoma type and characterized by the fusion oncogenes FUS -DDIT 3 or EWSR 1 -DDIT 3 . Previous analysis of cell cycle regulatory proteins revealed a prominent expression of G 1 -cyclins , cyclin dependent kinases , and their inhibitors but very few cells progressing through the G 1 /S boundary . Here , we extend the investigation to proteins involved in cell senescence in an immunohistochemistry based study of 17 MLS /RCLS cases . Large subpopulations of tumor cells expressed the RBL 2 pocket protein and senescence associated heterochromatin 1 γ and IL 8 receptor β . We conclude that MLS /RCLS tissues contain major populations of senescent tumor cells and this may explain the slow growth rate of this tumor type .