Diagnostic value of neutrophil gelatinase-associated lipocalin (NGAL) immunoexpression in follicular-patterned lesions of the thyroid gland

Abstract

Neutrophil gelatinase-associated lipocalin (NGAL) is a protein which participates in iron trafficking and which is involved in cancerogenesis and cancer progression. Since its over-expression has been documented in thyroid malignancies in comparison to thyroid normal gland, in the present study, we aimed to determine whether the evaluation of NGAL immunoexpression may be of help in the differential diagnosis of follicular-patterned thyroid lesions. Our additional aim was to test the possible interference of endogenous biotin on the immunohistochemical findings. Thus, all the immunohistochemical procedures, carried out with labeled streptavidin biotin method, were doubly performed, with or without the preliminary inhibition of endogenous biotin. No NGAL staining was found in the normal thyroid gland nor in the nodular colloid goiters or in Hashimoto's thyroiditis. NGAL expression appeared to be significantly more frequent in the malignant tumors in comparison to benign ones (P < 0.000001). Even more, NGAL expression appeared to be specific (specificity 93%) for carcinoma and represented a sensitive method (sensitivity 84%), with high negative (88%) and positive (94%) predictive values, as well as high diagnostic accuracy (88%), in the identification of follicular-patterned thyroid malignant tumors. The specificity, positive predictive value and diagnostic accuracy lowered when biotin was not preliminary inhibited, due to the presence of false positives among benign Hürthle cell tumors. In conclusion, the immunohistochemical detection of NGAL may be helpful in the differential diagnosis between malignant and benign follicular-patterned lesions of the thyroid. The use of biotin free system or the preliminary biotin inhibition is warranted for the detection of NGAL in thyroid samples, especially when dealing with Hürthle cell tumors.

The value of tumor markers in the diagnosis of papillary thyroid carcinoma alone and in combination

“…In line with research by Barresiet al [13,14],NGALexpressionappearedto bespecific(100%)forthyroidcarcinomaandrepresentedasensitivemethod(93%)inPTCincomparisontoC.Inaddition,thecontentoffollicularcavities inCalsoshowedoccasionalNGALexpression,while intumorswithfollicularstructure(suchasPTC-FV), it was negative. In conclusion, all these features of NGAL can contribute to differentiating malignant tumorsfrombenignlesions.Itwasnoteworthythat all immunohistochemical procedures were repeated severaltimeswithanendogenousbiotin-freesystem, butthecontentsofbenignthyroidfollicularcavities still occasionally showed NGAL protein expression, whichwaslikelytocauseNGALfalsepositivityinC.…”

“…The cells were regarded as positive for these proteins when immunoreactivity was clearly observed in their nuclei, membrane and/orcytoplasm.Stainingofthefollicularcolloidin the absence of staining of the follicular epithelium was considered nonspecific and negative. We used asemi-quantitativescoringmethodforeachimmunohistochemicalmarkerwiththecut-offvaluesbased ondatapublishedpreviously [4,11,[14][15][16][17]andthe clinicalexperienceofthepathologistsinvolved(NapingLiandXiWang).Thepercentageofpositivecells for each section was counted under 5 high power fields,andthemeanvalueofeachcasewasscoredas follows:0,stainingin<10%ofthecells;1,staining in10-25%ofthecells;2,stainingin26-50%ofthe cells; 3, staining in > 50% of the cells. A score of 0 was considered as negative, and scores of 1 to 3 wereconsideredaspositive.…”

“…It is involvedincancero-genesisandcancerprogressionby increasingironuptakefromtheextracellularspaceto inner cells which is essential for neoplastic cell multiplication [13].Barresiet al [13,14]reportedthat NGAL expression appeared to be significantly more frequent in the malignant thyroid tumors than in benignones,thelaterincludingfollicularadenomas, Hürthlecelladenomasandatypicaladenomas.What ismore,noNGALstainingwasfoundinthenormal thyroidgland,nodularcolloidgoitersorinHashimoto's thyroiditis. Hence, NGAL and claudin-1 might constituteaneffectiveauxiliarydiagnosisindexinthe discriminationofthyroidcarcinoma.…”

Roles of neutrophil gelatinase-associated lipocalin (NGAL) in human cancer

“…In contrast, no protein expression was detect by IHC (Human Protein Atlas web site). According to mRNA expression data, previous studies showed that NGAL is overexpressed in thyroid cancer [79-81]. …”

Neutrophil Gelatinase-Associated Lipocalin in Cancer

“…Barresi et al investigated whether or not NGAL immunoexpression using with a primary antibody (Santa Cruz Biotechnology) may be helpful for differential diagnosis of follicular-patterned thyroid lesions [70]. The thyroid tumors included 25 cases of follicular adenomas, 14 of Hürthle cell adenomas, 2 atypical adenomas, 10 minimally invasive follicular carcinomas (5 with capsular invasion only and 5 with both capsular and vascular invasion), 10 widely invasive follicular carcinomas, 3 Hürthle cell follicular carcinomas, and 8 follicular variant papillary carcinomas.…”