Research article

pRb2/p130 protein expression and RBL2 mutation analysis in Burkitt lymphoma from Uganda

Sam Kalungi^1,2 , Solrun J Steine¹ , Henry Wabinga² , Leif Bostad^1,3 and Anders Molven^1,3

¹Section for Pathology, the Gade Institute, University of Bergen, Bergen, Norway

²Department of Pathology, Makerere University College of Health Sciences, Kampala, Uganda

³Department of Pathology, Haukeland University Hospital, Bergen, Norway

author email corresponding author email

BMC Clinical Pathology 2009, 9:6doi:10.1186/1472-6890-9-6

Published:	19 August 2009

Abstract

Background

The members of the retinoblastoma protein family, pRb, p107 and pRb2 (p130), are central players in controlling the cell cycle. Whereas disturbed function of pRb is commonly seen in human cancers, it is still an open question whether pRb2 is involved in tumorigenic processes. However, altered subcellular localization of pRb2 and mutations in the pRb2-encoding gene RBL2 have been described for some tumours, including Burkitt lymphomas (BL).

Methods

We retrieved 51 biopsy specimens of endemic BL cases from Uganda. The expression of pRb2 was determined by immunohistochemistry. Exons 19-22 of the RBL2 gene, the region known to contain a nuclear localization signal, were screened for mutations by PCR amplification and direct DNA sequencing.

Results

Nearly all of our cases (84.0%) were positive for pRb2 protein expression although this protein is a marker for growth arrest and Burkitt lymphoma is characterized by a high proliferation rate. Of the positive cases, 73.8% were scored as expressing the protein at a high level. Subcellular pRb2 localization was predominantly nuclear and no cases with expression restricted to the cytoplasm were observed. We did not detect any RBL2 mutations in the part of the gene that encodes the C-terminal end of the protein.

Conclusion

The majority of endemic BL cases from Uganda express pRb2, but somatic RBL2 mutations affecting the protein's nuclear localization signal appear to be rare.