Expression of type IV collagen α1(IV)–α6(IV) polypeptides in normal and developing human kidney and in renal cell carcinomas and oncocytomas

✍ Scribed by Jouni Lohi; Matti Korhonen; Ilmo Leivo; Lauri Kangas; Taneli Tani; Raghuram Kalluri; Jeffrey H. Miner; Veli-Pekka Lehto; Ismo Virtanen

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: French
• Weight: 491 KB
• Volume: 72
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/(sici)1097-0215(19970703)72:1<43::aid-ijc6>3.0.co;2-4

✦ Synopsis

Type IV collagen trimer is a major component of basement membranes (BMs). It is composed of polypeptides named a1(IV)-a6(IV) chains. Chains a1,2(IV) are widely expressed in BMs while a3(IV)-a6(IV) are more restricted in human tissues. We have now studied by immunohistochemical means the distribution of collagen IV chains in fetal and adult human kidney, in oncocytomas, in renal cell carcinomas (RCCs) and their metastases and in experimental xenografts of human tumors. a1,2(IV) chains were found in all BMs of fetal and adult kidney as well as of renal tumors, while a3(IV)-a6(IV) chains were found in BMs of distal segments of developing and mature tubules. a3(IV)-a5(IV) chains were seen also in BMs of developing fetal glomeruli after the capillary loop stage. Most of the RCCs and their metastases showed occasional expression of a3(IV)-a6(IV) with papillary variants showing only expression of a5(IV) chain. There was a distinct expression of a3(IV)-a5(IV) chains in BMs of 3 oncocytomas. In 2 of them a variable expression of the a6(IV) chain was seen. In 3 of 4 xenografts, immunoreactivity for human-specific monoclonal antibody (MAb) for a1,2(IV) was seen in the BM-like structures. No a3-a6(IV) was seen in any of the xenografts, while polyclonal antiserum for type IV collagen presented immunoreactivity in BMs of all xenografts. Our results show that oncocytomas and most of the RCCs express scarce variants of type IV collagen containing a3(IV)-a6(IV) chains. In experimental xenograft tumors, both implanted RCC cells and host stromal cells have a capacity to produce type IV collagen.