J Korean Med Sci.  2007 Apr;22(2):305-310. 10.3346/jkms.2007.22.2.305.

Claudin-7 is Highly Expressed in Chromophobe Renal Cell Carcinoma and Renal Oncocytoma

Affiliations
  • 1Department of Pathology, Chonnam National University Medical School, 5 Hak-dong, Dong-gu, Gwangju, Korea. cchoi@chonnam.ac.kr
  • 2Department of Urology, Kwangju Christian Hospital, Gwangju, Korea.
  • 3Department of Surgery, Chonnam National University Medical School, Gwangju, Korea.
  • 4Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.
  • 5Department of Pathology, Dong-A University College of Medicine, Busan, Korea.
  • 6Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
  • 7Department of Pathology, The Methodist Hospital, Houston, Texas, U.S.A.

Abstract

Claudin-7 has recently been suggested to be a distal nephron marker. We tested the possibility that expression of claudin-7 could be used as a marker of renal tumors originating from the distal nephron. We examined the immunohistochemical expression of claudin-7 and parvalbumin in 239 renal tumors, including 179 clear cell renal cell carcinoma (RCC)s, 29 papillary RCCs, 20 chromophobe RCCs, and 11 renal oncocytomas. In addition, the methylation specific-PCR (MSP) of claudin-7 was performed. Claudin-7 and parvalbumin immunostains were positive in 3.4%, 7.8% of clear cell RCCs, 34.5%, 31.0% of papillary RCCs, 95.0%, 80.0% of chromophobe RCCs, and 72.7%, 81.8% of renal oncocytomas, respectively. The sensitivity and specificity of claudin-7 in diagnosing chromophobe RCC among subtypes of RCC were 95.0% and 92.3%. Those of parvalbumin were 80.0% and 88.9%. The expression pattern of claudin-7 was mostly diffuse in chromophobe RCC and was either focal or diffuse in oncocytoma. All of the cases examined in the MSP revealed the presence of unmethylated promoter of claudin-7 without regard to claudin-7 immunoreactivity. Hypermethylation of the promoter might not be the underlying mechanism for loss of its expression in RCC. Claudin-7 can be used as a useful diagnostic marker in diagnosing chromophobe RCC and oncocytoma.

Keyword

Chromophobe Renal Cell Carcinoma; Oncocytoma; Claudin-7
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