HMGB1 and HMGB2 Expression Patterns in Human Papillary Renal Cancers

Takumi Takeuchi,Masayoshi Zaitsu,Koji Mikami,Yuta Takeshima,Toshimasa Uekusa,Akiko Tonooka,Koichi Sakazume,Mami Hattori

doi:10.4236/oju.2013.31005

Abstract

High mobility group box (HMGB) proteins are nuclear nonhistone chromosomal proteins that bend DNA, bind preferentially to distorted DNA structures, and promote the assembly of site-specific DNA binding proteins. Recent reports indicate that HMGB1 has a dual function, a cytokine in addition to a nuclear protein. The increased expression of HMGB1 has been reported for several different tumors. Here, we assessed HMGB1 and HMGB2 expressions in two cases of papillary renal cell carcinoma. One case with pT1a, Grade 2 showed HMGB1 expression in the nucleus and cytosol and HMGB2 expression in the nucleus, but not in the cytosol. In the other case, there were three renal tumors, one of which was clear cell renal cell carcinoma with pT1a, Grade 3 and two were papillary renal cell carcinomas, Grade 2 (5 mmand2 mmin the diameter). Both HMGB1 and HMGB2 were expressed in the nucleus and cytosol of papillary carcinoma. In the clear cell carcinoma of this case, HMGB1 expression was stained both in the nucleus and cytosol, while HMGB2 was observed in the nucleus, but not in the cytosol. More samples need to be further investigated in order to draw conclusions concerning HMGB expressions in papillary renal cell carcinomas.

Highlights

High mobility group box (HMGB) proteins are nuclear nonhistone chromosomal proteins that bend DNA, bind preferentially to distorted DNA structures, and promote the assembly of site-specific DNA binding proteins leading to the regulation of gene transcription [1]
In the clear cell carcinoma of this case, HMGB1 expression was stained both in the nucleus and cytosol, while HMGB2 was observed in the nucleus, but not in the cytosol
HMGB1/2 expression in papillary renal cancer has not previously been reported. In both cases of papillary renal cell carcinoma in the present study whose pathological stage is pT1a, HMGB1 was expressed in the cytosol as well as in the nucleus

Summary

Introduction

High mobility group box (HMGB) proteins are nuclear nonhistone chromosomal proteins that bend DNA, bind preferentially to distorted DNA structures, and promote the assembly of site-specific DNA binding proteins leading to the regulation of gene transcription [1]. Ubiquitous expressions of HMGB1 and HMGB2 have the potential to regulate the transcriptional activity of different members of the p53 family in cell-specific and promotor-specific manners in vivo [13]. Both HMGB1 and HMGB2 are sensors of DNA damage inducing a p53-mediated DNA damage response, abrogation of which increased chemoresistance in some cancer cell lines [14]. We have concluded that HMGB1expressed in the cytoplasm was correlated with poor pathological characteristics In this line, we assessed HMGB1 and HMGB2 expressions in two cases of papillary renal cell carcinoma. Papillary renal cell carcinoma is the second most common subtype of RCC next to the clear cell subtype and activating mutations in the tyrosine kinase domain of MET have been detected in the hereditary and sporadic type 1 papillary renal cell carcinomas [16]

Immunohistochemistry

Case Presentation

Findings

Discussion