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

Kalungi S, Steine SJ, Wabinga H, Bostad L, Molven A - BMC Clin Pathol (2009)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section for Pathology, the Gade Institute, University of Bergen, Bergen, Norway. skalungi@gmail.com

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 1922 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.

No MeSH data available.


Related in: MedlinePlus

Representative examples of pRb2 staining in BL patients from Uganda. A) Negative staining (original magnification: ×400). B) Low staining, i.e. less than 50% of tumour cells expressing pRb2 (original magnification: ×400). C) High staining, i.e. more than 50% of tumour cells expressing pRb2 (original magnification: ×400) D) Cytoplasmic expression of pRb2 in tumour cells undergoing mitosis. Dividing cells are indicated by arrows (original magnification: ×630).
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Figure 1: Representative examples of pRb2 staining in BL patients from Uganda. A) Negative staining (original magnification: ×400). B) Low staining, i.e. less than 50% of tumour cells expressing pRb2 (original magnification: ×400). C) High staining, i.e. more than 50% of tumour cells expressing pRb2 (original magnification: ×400) D) Cytoplasmic expression of pRb2 in tumour cells undergoing mitosis. Dividing cells are indicated by arrows (original magnification: ×630).

Mentions: Forty-two (84.0%) of the 50 cases for which immunohistochemical data could be obtained, stained positively for pRb2 while eight (16.0%) were negative (Table 2). Among the positives, immune reactivity varied from close to 100% of the tumour cells to only a few positive cells in the section (Figure 1A-1C). The staining was predominantly nuclear. Also, cells undergoing mitosis were positive, with immune reactivity present throughout the cytoplasm (Figure 1D). Table 2 shows the staining scores for the cases included in the study. We did not find any statistically significant association between pRb2 staining (positive/negative) and age below 8 years (p = 0.69), or gender (p = 0.71), or tumour site (p = 1.00). Of the 42 positive cases, 31 (73.8%) cases were scored as highly expressing tumours and 11 (26.2%) as low-expressing. pRb2 staining (high versus low) did not show any statistically significant association with tumour site (p = 0.86), gender (p = 0.88), or age (p = 0.71).


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

Kalungi S, Steine SJ, Wabinga H, Bostad L, Molven A - BMC Clin Pathol (2009)

Representative examples of pRb2 staining in BL patients from Uganda. A) Negative staining (original magnification: ×400). B) Low staining, i.e. less than 50% of tumour cells expressing pRb2 (original magnification: ×400). C) High staining, i.e. more than 50% of tumour cells expressing pRb2 (original magnification: ×400) D) Cytoplasmic expression of pRb2 in tumour cells undergoing mitosis. Dividing cells are indicated by arrows (original magnification: ×630).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2735744&req=5

Figure 1: Representative examples of pRb2 staining in BL patients from Uganda. A) Negative staining (original magnification: ×400). B) Low staining, i.e. less than 50% of tumour cells expressing pRb2 (original magnification: ×400). C) High staining, i.e. more than 50% of tumour cells expressing pRb2 (original magnification: ×400) D) Cytoplasmic expression of pRb2 in tumour cells undergoing mitosis. Dividing cells are indicated by arrows (original magnification: ×630).
Mentions: Forty-two (84.0%) of the 50 cases for which immunohistochemical data could be obtained, stained positively for pRb2 while eight (16.0%) were negative (Table 2). Among the positives, immune reactivity varied from close to 100% of the tumour cells to only a few positive cells in the section (Figure 1A-1C). The staining was predominantly nuclear. Also, cells undergoing mitosis were positive, with immune reactivity present throughout the cytoplasm (Figure 1D). Table 2 shows the staining scores for the cases included in the study. We did not find any statistically significant association between pRb2 staining (positive/negative) and age below 8 years (p = 0.69), or gender (p = 0.71), or tumour site (p = 1.00). Of the 42 positive cases, 31 (73.8%) cases were scored as highly expressing tumours and 11 (26.2%) as low-expressing. pRb2 staining (high versus low) did not show any statistically significant association with tumour site (p = 0.86), gender (p = 0.88), or age (p = 0.71).

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section for Pathology, the Gade Institute, University of Bergen, Bergen, Norway. skalungi@gmail.com

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 1922 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.

No MeSH data available.


Related in: MedlinePlus