Apoptosis and proliferation related molecules (Bcl-2, Bax, p53, PCNA) in papillary microcarcinoma versus papillary carcinoma of the thyroid.
OBJECTIVE
To gain a better insight into the differences in biological behaviour between papillary microcarcinoma (PMC) and clinically evident papillary thyroid carcinoma (PTC).


METHODS
Immunohistochemical analysis of apoptosis related molecules (Bcl-2, Bax, p53) and proliferation related marker (PCNA) in 39 archival cases of PMC and 46 cases of PTC.


RESULTS
Bcl-2 and Bax were expressed in most PMCs and PTCs. The average Bcl-2 staining score did not differ significantly between PMCs and PTCs (p > 0.05), but the average Bax score was significantly lower in PMCs (p < 0.05). The Bcl-2/Bax ratio was significantly higher in PMCs than in PTCs (p < 0.05). The expression of p53 was similar in PMCs and PTCs, without a correlation with clinical data, but was associated with high Bax expression (p < 0.05) in these cases in both groups. Non-malignant tissue expressed only Bcl-2, but not p53 or Bax. PCNA expression was significantly lower (p < 0.05) in PMC than in PTC and positively correlated with tumour size (p < 0.05).


CONCLUSIONS
The higher Bcl-2/Bax ratio and lower proliferative activity in PMC suggest differences from PTC in the balance between apoptosis and proliferation. However, the presence of p53 and Bax in PMC indicates malignant potential, and thus PMC should be treated with caution.
Cvejic
Dubravka
D
Institute for the Application of Nuclear Energy-INEP, University of Belgrade, Serbia. dubravka@inep.co.yu
Selemetjev
Sonja
S
Savin
Svetlana
S
Paunovic
Ivan
I
Petrovic
Ivana
I
Tatic
Svetislav
S
D000231:Adenocarcinoma, Papillary / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D017209:Apoptosis / Q000502:physiology; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis*
D018809:Proliferating Cell Nuclear Antigen; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein