Open AccessA novel form of pRb expressed during normal myelopoiesis and in tumour‐associated macrophages
Author(s) -
Liu H. P.,
Thompson A. M.,
Macleod K. F.
Publication year - 2005
Publication title -
cell proliferation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.647
H-Index - 74
eISSN - 1365-2184
pISSN - 0960-7722
DOI - 10.1111/j.1365-2184.2005.00326.x
Subject(s) - myelopoiesis , myeloid , retinoblastoma , biology , cancer research , retinoblastoma protein , spleen , bone marrow , cell cycle , microbiology and biotechnology , cell , immunology , haematopoiesis , genetics , stem cell , gene
. The retinoblastoma (Rb) tumour suppressor promotes cell cycle exit, terminal differentiation and survival during normal development and is functionally inactivated in most human cancers. We have identified a novel myeloid‐specific form of retinoblastoma protein (pRb), termed ΔRb‐p70, that exists in vivo as an N‐terminally truncated form of full‐length pRb. ΔRb‐p70 appears to be the product of alternative translation and is expressed in primary myeloid cells in fetal liver, bone marrow and spleen. It is also expressed in the human myelomonocytic cell line U937 and is down‐regulated as U937s are induced to differentiate. We have also detected ΔRb‐p70 expression in primary human breast tumours and we have determined that ΔRb‐p70 is specifically expressed in tumour‐associated macrophages. These data identify a novel mechanism for regulating pRb expression that is unique to the myeloid system.