Immunohistochemical detection of Hsp90 and Ki-67 in pterygium

Diagnostic Pathology (Impact Factor: 2.6). 02/2013; 8(1). DOI: 10.1186/1746-1596-8-32
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To examine the immunohistochemical expression of heat shock protein 90 (Hsp90) and Ki-67 protein in human pterygium.

Materials and methods
Tissues obtained during pterygium surgery of 15 patients who underwent the bare-sclera procedure and 10 normal conjunctivae were studied. All of these pterygia were primary ones. Recurrent pterygia were excluded. Normal bulbar conjunctivas (2 x 2 mm) were obtained from the nasal region close to the limbus from patients during their cataract and retina surgeries. Immunohistochemical detection of Hsp90 and Ki67 was done using the streptavidin–biotin method in paraffin embedded tissue sections.

The percentage of cells stained for Hsp90 was greater for pterygium epithelium (76 ± 10.8) than for normal conjunctiva (1.4 ± 0.8). In each pterigyum sample more than 60% of cells were positive. The differences in positive cells between normal and pterigyum epithelium were highly significant for Hsp90 (P < 0,001).
Pterygium epithelium also showed a higher percentage of cells that stained for Ki67 (10.1 ± 9.5) than for normal conjunctiva (2.1 ± 1.9). The differences in positive cells were also statistically significant for Ki67 (P < 0.01). Although there were significant differences in the majority of samples observed. It was noted that in some samples there was no difference between normal and pterygium epithelium for Ki67.

Our results indicate an abnormal expression of Hsp90 and ki-67 in pterygium samples when compared to normal conjunctiva.The finding of abnormal expression of levels of Hsp90 in pterygium samples can stimulate new research into pterygium and its recurrence.

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Available from: Maria E Orellana, Mar 03, 2014
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    • "Immunohistochemically, a significantly higher percentage of immunopositive epithelial pterygial cells for Hsp90 and Hsp27 was detected in pterygia whereas the expression levels of Hsp70 did not differentiate between normal conjunctival and pterygium epithelium (Table 3). A recent study by Sebastiá et al. [70] also reported highly statistically significant differences in Hsp90 positive cells between normal conjunctiva and pterygium epithelium. "
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    ABSTRACT: Εnhanced expression of transcription factor hypoxia inducible factor HIF-1α is known to play a critical role in the modulation of cell metabolism and survival pathways as well as having stem-cell-like properties. Furthermore, accumulated data reveal the existence of cross-regulation between the oxygen-sensing and heat shock pathways contributing to the adaptation of cells under stressful conditions. Pterygium, a stem cell disorder with premalignant features, has been reported to demonstrate hypoxia. The purpose of this study was to investigate the co-expression patterns of transcription factor HIF-1α and von Hippel Lindau protein (pVHL)-which normally acts to keep levels of HIF-1α activity low under normoxic conditions-in pterygium and normal conjunctival human samples. Additionally, expression of HIF-1α compared to the activation of heat shock proteins (Hsp90, Hsp70, and Hsp27) was studied. Emphasis was placed on the detection of HIF-1α and Hsp90, which associates with and stabilizes HIF-1α to promote its transcriptional activity. Semi-serial paraffin-embedded sections and tissue extracts from pterygium and normal conjunctival samples were studied by immunohistochemistry and western blot analysis, respectively, with the use of specific antibodies. Double labeling immunofluorescence studies on cryostat sections were also included. Statistically significant increased expression of HIF-1α and Hsps (Hsp90, Hsp70, and Hsp27) in pterygia compared to normal conjunctiva was demonstrated (p<0.05). In contrast, no significant difference was detected for pVHL expression (p>0.05). Immunohistochemical findings revealed nuclear HIF-1α immunoreactivity in all the epithelial layers of 23/32 (71.8%) pterygium tissues. Furthermore, all epithelial layers of the majority (75%) of pterygium samples showed strong cytoplasmic immunoreactivity for Hsp27 while Hsp27 expression was detected in all pterygia (100%) examined. Hsp27 expression was not observed in the superficial layer of goblet cells. In some samples, focal basal epithelial cells exhibited weak Hsp27 expression or were Hsp27 immunonegative. Ιmmunoreactivity of phopsho-Hsp27 showed the same distribution pattern as Hsp27 did. Epithelium of all pterygia (100%) displayed moderate to strong Hsp90 cytoplasmic immunoreactivity. Furthermore, the majority of pterygia, specifically, 30/32 (93.7%) and 27/32 (84.3%) demonstrated, respectively, Hsp70 and pVHL cytoplasmic immunoreactivity. Hsp90, Hsp70, and pVHL immunoreactivity was mainly detected in basal and suprabasal epithelial layers even though strong immunoreactivity in all epithelial layers was also observed in some pterygia. Stroma vessels were immunopositive for Hsps (Hsp90, Hsp70, and Hsp27) and pVHL. A statistically significant correlation between the expression of HIF-1α and the activation status of Hsps (Hsp90, Hsp70, and Hsp27; p<0.05) was observed whereas HIF-1α expression did not correlate with pVHL expression (p>0.05). Double labeling immunofluorescence studies showed nuclear HIF-1α co-localization with cytoplasmic Hsp90 expression in cells distributed in the entire epithelium of pterygia, in contrast to, normal conjunctiva, which exhibited only a few scattered epithelial cells with cytoplasmic HIF-1α expression and basal epithelial cells with Hsp90 expression. The upregulation of coordinated activation of HIF-1α and Hsps in pterygium may represent an adaptive process for the survival of cells under stressful conditions. The significance of the association of HIF-1α with Hsp90 with respect to the therapeutic approach of pterygium requires further evaluation.
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    • "As far as our case is concerned, the rarity of cystically dilated glands, the marked atypia of the lesional cells and the focal pagetoid spread, suggesting, per se, worrisome histological findings, were in keeping with the diagnosis of atypical nevus. Ki-67 findings were not significantly increased if compared to normal conjunctiva [6] Immunohistochemical results concerning p16 were in line with our histological findings. p16 protein regulates the cell cycle and plays a major role in melanomagenesis, and is expressed in several types of benign melanocytic nevi [7]. "
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    ABSTRACT: Virtual slides The virtual slide(s) for this article can be found here: Melanocytic nevi are the most common tumors of the conjunctiva, accounting for 28% of all neoplastic lesions. These tumors, despite their benign behavior, share some atypical histological features with nevi found in other anatomic sites like the genital and acral regions, globally designated as nevi with site-related atypia. Moreover, in children and adolescents, rapidly growing conjunctival nevi show sometimes worrisome histological patterns in association with a prominent inflammatory infiltrate that may lead to diagnostic problems. In this paper we describe a juvenile compound nevus characterized by marked melanocytic atypia and severe inflammation, which can be considered a rare case of juvenile conjunctival atypical nevus. The final diagnosis relied on morphological and immunohistochemical characterization of the large epithelioid melanocytic cells, and on the results of FISH analysis.
    Diagnostic Pathology 04/2013; 8(1):64. DOI:10.1186/1746-1596-8-64 · 2.60 Impact Factor
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    • "The imunohistochemical staining results showed although Ki67 labeling index was variable in NF, there was generally a higher expression level (mean index 23.71±15.01%). Ki67 has been proved to be a useful marker for distinguishing many benign and malignant lesions [6,7]. Gong et al. [19] found a significantly higher expression of Ki67 in ghost cell odontogenic carcinoma than in calcifying cystic odontogenic tumor. "
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