THE ROLE OF JAK-STAT SIGNALING PATHWAY IN CHOLESTEATOMA: AN IMMUNOHISTOCHEMICAL ASSAY

Görkem Eskiizmir,1 H. Seda Vatansever,2 Erdoğan Özgür,3 Asım Aslan,4 Derya Gözüaçık,5 M. Kemal Özbilgin,2 Cemal Cingi6

1 Associate Professor, Department of Otolaryngology-Head & Neck Surgery, Celal Bayar University, Manisa, Turkey; 2Professor, Department of Histology & Embryology, Celal Bayar University, Manisa, Turkey; 3Resident, Department of Otolaryngology-Head & Neck Surgery, Celal Bayar University, Manisa, Turkey; 4Professor, Department of Otolaryngology-Head & Neck Surgery, Celal Bayar University, Manisa, Turkey; 5Resident, Department of Histology & Embryology, Celal Bayar University, Manisa, Turkey; 6Professor, Department of Otolaryngology-Head & Neck Surgery Osmangazi University, Eskişehir, Turkey

Introduction

Histologically, the epithelium of cholesteatoma is similar to the epidermis of the skin, however, uncontrolled keratinocyte hyperproliferation is one of the major differences.1 In literature, the relationship between cytokines and uncontrolled keratinocyte hyperproliferation in cholesteatoma has been demonstrated in several studies.2,7 The biological functions of cytokines such as cell activation, proliferation, differentiation, and survival or apoptosis are triggered by signal transduction cascades. One of the major cellular signalling pathways for cytokines is Janus tyrosine kinase (Jak)/signal transducers and activators of transcription terminators (Stat) signaling pathway. In addition, any perturbation in Jak/Stat signaling pathway may predispose dysregulation of cellular proliferation, differentiation, and apoptosis, which processes also have a significant part in the pathogenesis of cholesteatoma.

Patients and methods

Skin and cholesteatoma specimens were obtained from ten patients who underwent otological surgeries for chronic otitis media with cholesteatoma (n = 10). Skin specimens were obtained from external acoustic meatus after surgical incision. Both skin and cholesteatoma specimens were collected for histopathological and immunohistochemical examination.

The intensity of immunostaining for each parameter (Jak1, Jak2, Jak3, Stat1, Stat2, Stat3, Stat4, and Stat5) was graded as: (i) no staining: 0; (ii) weakly stained: 1; (iii) moderately stained: 2; and (iv) strongly stained: 3. In addition, H-score measurement [Σn (i+1); n: percentage of immunostained cells, i: intensity of immu-nostained cells] was performed for cholesteatoma and skin specimens individually.

Results

In cholesteatoma, Jak1, Jak2, Jak3, Stat1 and Stat3 immunoreactivities were absent; on the other hand, Jak1, Jak2, Jak3, Stat1 and Stat3 immunoreactivities were detected in skin specimens. In addition, the comparison of cholesteatoma and skin demonstrated a statistically significant difference for Jak1, Jak2, Jak3, Stat1 and Stat3. Stat2, Stat4 and Stat5 immunoreactivities were detected in both cholesteatoma (mean values of 172.8, 166.7 and 120.0) and skin (mean values of 400.0, 284.9 and 292.0) specimens. However, the differences between the H-scores of cholesteatoma and skin were statistically significant for Stat1, Stat4 and Stat5.

Discussion

In this study, absence of Jak1, Jak2 and Jak3 immunoreactivities in cholesteatoma was determined; in contrast, Jak1 (H-score: 149), Jak2 (H-score: 289) and Jak3 (H-score:32) immunoreactivities were detected in skin. It was demonstrated that Jak3-deficient mice had a high apoptotic index and Jak3 provides survival signals, in the light of this knowledge we believe that absence of Jak kinases in cholesteatoma may augment the apop-totic processes in keratinocytes which also have a behavior of uncontrolled hyperproliferation. A statistically significant difference between Stat1 and Stat5 immunoreactivity of cholesteatoma and skin was determined (p = 0.0005, p < 0.0001). Stat1 is a negative regulator of cell growth and have an proapoptotic effect8 Stat5 is an important regulator protein for hyperproliferation and differentiation.9 Ultimately, we believe that the absence or deficiency in the members of Jak/Stat signaling pathway may trigger the uncontrolled hyperproliferation, migration of keratinocytes and apoptotic processes in cholesteatoma.

References

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2.Yan SD, Huang CC. Tumor necrosis factor alpha in middle ear cholesteatoma and its effect on keratinocytes in vitro. Ann Otol Rhinol Laryngol 100:157–161, 1991

3.Bujia J, Kim C, Ostos P, Kastenbauer E, Hultner L. Role of interleukin 6 in epithelial hyperproliferation and bone resorption in middle ear cholesteatomas. Eur Arch Otorhinolaryngol 253:152–157, 1996

4.Chung JW, Yoon TH. Different production of interleukin-1a interleukin-1b and interleukin-8 from cholesteatomatous and normal epithelium. Acta Otolaryngol (Stockh.) 118:386–391, 1998

5.Ottaviani F, Neglia CB, Berti E. Cytokines and adhesion molecules in middle ear. A role in epithelial growth? Acta Otolaryngol 119:462–467, 1999

6.Yetiser S, Satar B, Aydin N. Expression of epidermal growth factor tumor necrosis factor-alpha and interleukin-1alpha in chronic otitis media with or without cholesteatoma. Otol Neurotol 23:647–652, 2002

7.Yamamoto-Fukuda T, Takahashi H, Terakado M, Hishikawa Y, Koji T. Expression of keratinocyte growth factor and its receptor in noncholesteatomatous and cholesteatomatous chronic otitis media. Otol Neurotol 31:745–751, 2010

8.O’Shea JJ, Gadina M, Schreiber RD. Cytokine signalling in 2002: New surprises in Jak/Stat pathway. Cell 109:S121-S131, 2002

9.Nosaka T, Kawashima T, Misawa K, et al. STAT5 as a molecular regulator of proliferation, differentiation and apoptosis in hematopoietic cells. EMBO J. 18:4754–4765, 1999


Address for correspondence: Görkem Eskiizmir, MD, FTBORLHNS, Celal Bayar University, Department of Otolaryngology-Head Neck Surgery, Manisa, Turkey. geskiizmir@hotmail.com

Cholesteatoma and Ear Surgery - An Update, pp. 211–212

Edited by Haruo Takahashi

2013 © Kugler Publications, Amsterdam, The Netherlands