Association of cytokeratin 17 expression with differentiation in oral squamous cell carcinoma

Abstract

Purpose: The aim of this study was to confirm the expression profile of cytokeratin (CK)17 in comparison with that of CK13 in oral squamous cell carcinoma (OSCC) and leukoplakia and to clarify an association of CK17 with the OSCC differentiation.

Materials: The expression of CK17 and CK13 was immunohistochemically examined in 105 patients with OSCC and 108 patients with leukoplakia. A correlation of CK expression with clinicopathological variables was carried out. The over-expression levels of CK17 mRNA were analyzed by real-time RT-PCR in 5 OSCC cell lines (HSC-2, HSC-3, SAS, SQUU-A, SQUU-B).

Results: CK17 and CK13 were detected in 101 (96.2 %) and three (2.9 %) of the 105 OSCCs, respectively. CK17 was significantly expressed in well-differentiated OSCC compared to moderately/poorly differentiated OSCC (p < 0.01). As detected in 19 of the 34 dysplastic leukoplakias (55.9 %) and 36 of the 74 hyperplastic leukoplakias (48.6 %), CK17 was significantly expressed in dysplastic leukoplakias (p < 0.01). As detected in 11 of the 34 dysplastic (32.4 %) and 52 of the 74 hyperplastic leukoplakias (70.3 %), CK13 was significantly expressed in hyperplastic leukoplakias (p < 0.01). The relative expression of CK17 mRNA in HSC-2 was significantly higher than in HSC-3 and SAS (p < 0.05). Moreover, the relative expression of CK17 mRNA in SQUU-A was significantly higher than in SQUU-B (p < 0.05).

Conclusion: CK17 expression could be associated with the differentiation and the malignancy of OSCC. A combination pattern of CK17/CK13 might be a suitable marker of malignant transformation.

Fig. 1

Immunohistochemical staining of CK17 and CK13 in OSCC. Serial sections were stained with HE (a, b, c) anti-CK17 antibody (d, e, f), and anti-CK13 antibody (g, h, i), and each representative case is shown here. In well-differentiated OSCC, CK17 was strongly expressed in the majority of tumor cells and was strongly expressed in the inner of cancer nest (d). In moderately differentiated OSCC, CK17 was weakly expressed in the majority of tumor cells (e). In poorly differentiated OSCC, CK17 was not expressed in the majority of tumor cells (f). CK13 was not expressed in most of OSCC cases (g–i). (Original magnification ×100, scale bars 100 μm)

Fig. 2

A representative case of OSCC with dysplasia, cancer nests, and infiltrating cells. Serial sections were stained with HE (A, a–c) and anti-CK17 antibody (B, d–f). High-magnification views of selected areas are shown (a–f). CK17 was markedly expressed in dysplasia, while not in normal epithelium (d). CK17 was obviously expressed in the inner layer of cancer nest, while not in the outer (e). CK17 was absent in the infiltrating cells (f). (Original magnification ×40, scale bars 200 μm)

Fig. 3

Immunohistochemical staining of CK17 and CK13 in the normal oral epithelium and dysplastic and hyperplastic leukoplakias. Serial sections were stained with HE (a–c), anti-CK17 antibody (d–f), and anti-CK13 antibody (g–i), and each representative case is shown here. CK17 was not expressed in normal oral epithelium and hyperplastic leukoplakia (d, e). CK17 was markedly expressed (f) in dysplastic leukoplakia. CK13 was expressed in normal oral epithelium and hyperplastic leukoplakia (g, h) and not expressed in dysplastic leukoplakia (i). (Original magnification ×100, scale bars 100 μm)

Fig. 4

Percentage of CK17- and CK13-positive cases in normal oral epithelium, leukoplakia, and OSCC. The percentages of CK17-positive cases were 0/10 (0 %), 35/74 (48.6 %), 18/34 (54.5 %), and 101/105 (96.2 %), respectively, while the percentages of CK13-positive cases were 10/10 (100 %), 52/74 (70.3 %), 11/34 (32.4 %), and 3/105 (2.9 %), respectively, in normal oral epithelium, hyperplastic leukoplakia, dysplastic leukoplakia, and OSCC

Fig. 5

Immunohistochemical staining of CK17 and CK13 in the border between dysplastic leukoplakia and hyperplastic leukoplakia. CK17 was clearly expressed in dysplastic leukoplakia, while it was disappeared in hyperplastic leukoplakia (a). CK13 was disappeared in dysplastic leukoplakia, while it was clearly expressed in hyperplastic leukoplakia (b). A reciprocal expression of CK17 and CK13 could be found between the two different lesions (original magnification×100, scale bars 100 μm)

Fig. 6

Relative expression of CK17 mRNA in OSCC cell lines and human epithelium cell line. The relative expression of CK17 mRNA in HSC-2 was significantly higher than in HSC-3 and SAS. Moreover, the relative expression of CK17 mRNA in SQUU-A was significantly higher than in SQUU-B. The relative expression of CK17 mRNA in HaCaT was significantly lower than the others. Statistical analyses were performed by Student’s t-test