title: Claudin-7 is highly expressed in chromophobe renal cell carcinoma and renal oncocytoma.
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.
authors: Department of Pathology, Chonnam National University Medical School, 5 Hak-dong, Dong-gu, Gwangju, Korea.
authors: Yoo Duk
authors: YD
authors: Choi
authors: Ki Seung
authors: KS
authors: Kim
authors: Sunhyo
authors: S
authors: Ryu
authors: Youngkyu
authors: Y
authors: Park
authors: Nam Hoon
authors: NH
authors: Cho
authors: Seo Hee
authors: SH
authors: Rha
authors: Ja June
authors: JJ
authors: Jang
authors: Jae Y
authors: JY
authors: Ro
authors: Sang Woo
authors: SW
authors: Juhng
authors: Chan
authors: C
authors: Choi
mesh_terms: D018249:Adenoma, Oxyphilic / Q000175:diagnosis* / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000378:metabolism*; D057167:Claudins; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D009399:Nephrons / Q000378:metabolism; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
chemical_list: D014408:Biomarkers, Tumor; C473255:CLDN7 protein, human; D057167:Claudins; D008565:Membrane Proteins; D009363:Neoplasm Proteins