Parafibromin expression in breast cancer: a novel marker for prognostication?
BACKGROUND
Parafibromin is a novel protein product of HRPT2, a recently identified tumour suppressor gene. Mutations of the HRPT2 gene are common in parathyroid carcinomas, and these exhibit reduced protein expression. Parafibromin expression in breast cancer has not been previously studied.


OBJECTIVE
To determine the distribution of parafibromin in breast cancer tissues, and correlate its expression with conventional pathological parameters.


METHODS
Tissue microarrays were constructed from archival paraffin embedded breast cancer samples. Sections cut from tissue microarray blocks were subjected to immunohistochemistry. Immunopositivity for parafibromin and intensity-percentage scores were derived by blinded evaluation. Findings were correlated with clinicopathological parameters.


RESULTS
163 breast cancers were assessed. Larger tumours were less likely to express parafibromin than smaller ones, with the association approaching statistical significance (p = 0.05). Staining intensity correlated inversely with tumour size (p = 0.016) and pathological stage (p = 0.008); as did parafibromin intensity-percentage score with pathological stage (p = 0.03), lymphovascular invasion (p = 0.03) and cerbB2 intensity-percentage score (p = 0.04).


CONCLUSIONS
Parafibromin in breast cancer, as in parathyroid tumours, appears to have tumour suppressor functions, with loss of protein expression associated with adverse pathological parameters. These findings may indicate a potential role of parafibromin as a prognostic marker in breast cancer.
Selvarajan
S
S
Department of Pathology, Singapore General Hospital, Singapore.
Sii
L-H
LH
Lee
A
A
Yip
G
G
Bay
B-H
BH
Tan
M-H
MH
Teh
B-T
BT
Tan
P-H
PH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000378:metabolism; D009367:Neoplasm Staging; D011379:Prognosis; D046888:Tissue Array Analysis / Q000379:methods; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
D014408:Biomarkers, Tumor; C454900:CDC73 protein, human; D009363:Neoplasm Proteins; D025521:Tumor Suppressor Proteins