B cell receptor signaling suppressor SHP-1 is active in CLL lymph node and peripheral blood

• Protein tyrosine phosphatase SHP-1 expression and activity is downregulated or lost in several leukemias and lymphomas due to DNA promotor hypermethylation, catalytic site mutation or oxidation, or phosphorylation at inhibitory sites, implying a negative role of SHP-1 in development of leukemias/lymphomas. In chronic lymphocytic leukemia (CLL), B cell receptor (BcR) and microenvironment signal levels are important in the pathogenesis. Considering that SHP-1 is a BcR signaling suppressor, we hypothesized that SHP-1 would be down-regulated and/or inactivated in the proliferative center lymph node (LN) cells. We analyzed PTPN6 (SHP-1) gene expression, SHP-1 protein expression and phosphorylation status in matched CD5+/CD19+ peripheral blood (PB) and LN cells from 6 CLL patients, and in comparison, BcR (anti-IgM) in vitro triggered CLL PB cells from 10 patients. Gene expression of PTPN6 was significantly higher in PB compared to LN CLL cells in 50% of the cases. SHP-1 protein expression level and phosphorylation at SHP-1Y536 and SHP-1S591 were, however, equal in PB and LN samples. SHP-1 phosphorylation at Y536 and S591, in PB CLL cells cultured ex vivo was significantly reduced upon BcR engagement in all patient samples. These results indicate that in vivo BcR signaling in CLL is paralyzed.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Cell- och molekylärbiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Cell and Molecular Biology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

Keyword

B cell

chronic lymphocytic leukemia

SHP-1

suppressor

tyrosine phosphorylation

Publication and Content Type

vet (subject category)

ovr (subject category)