IMP3 Expression in Thyroid Carcinomas
WC Huang, YM Jeng. National Taiwan University Hospital, Taipei, Taiwan; National Taiwan University, Taipei, Taiwan
Background: The majority of carcinomas of follicular cell origin are indolent, and undifferentiated thyroid carcinoma represents the most aggressive tumor of the thyroid gland. Poorly differentiated thyroid carcinoma lies in-between well-differentiated and undifferentiated carcinoma morphologically, immunohistochemically, and behaviorally. The insulin-like growth factor mRNA-binding protein 3 (IGF2BP3, IMP3) is a prognostic biomarker in renal clear cell carcinoma, low-stage urothelial carcinoma of the bladder, ovarian clear cell carcinoma and hepatocellular carcinoma. Our aim is to evaluate the expression of IMP3 protein and its possible influence on prognosis in thyroid carcinomas.
Design: From the surgical pathological files compiled during 1988-2004, we selected 175 specimens of thyroid cancer, including 96 cases of papillary carcinoma, 47 cases of follicular carcinoma, 12 cases of poorly differentiated carcinoma and 20 cases of undifferentiated carcinoma. These specimens were obtained from a total of 130 patients; amongst these, 30 patients had multiple surgical specimens, including primary, metastatic and recurrent lesions. IMP3 protein expression was analyzed by immunohistochemistry.
Results: Negative IMP3 immunostaining was found in the majority of papillary carcinoma (83.3%), follicular carcinoma (85.1%) and poorly differentiated carcinoma (66.7%). In contrast, IMP3 protein was extensively expressed in most cases of undifferentiated carcinoma (95.0%). The background thyroid tissues in all specimens were negative for IMP3 staining.
|Extent of IMP3 staining||Total|
|Papillary carcinoma||80 (83.3%)||13 (13.5%)||1 (1.0%)||2 (2.1%)||96|
|Follicular carcinoma||40 (85.1%)||5 (10.6%)||0 (0%)||2 (4.3%)||47|
|Poorly differentiated carcinoma||8 (66.7%)||1 (8.3%)||3 (25%)||0 (0%)||12|
|Undifferentiated carcinoma||1 (5.0%)||0 (0%)||0 (0%)||19 (95.0%)||20|