Tumor progression is associated with a significant decrease in the expression of the endostatin precursor collagen XVIII in human hepatocellular carcinomas.
Endostatin inhibits angiogenesis and tumor growth in mice. The role of its endogenous precursor collagen XVIII in human cancer is unknown. In normal tissues, two variants of collagen XVIII, namely, the short and long forms regulate tissue specificity, the long form being almost exclusively expressed by hepatocytes in the liver. We analyzed RNA arrays from 57 hepatocellular carcinomas (HCCs) with common and variant-specific probes and investigated the relationships between collagen XVIII expression and angiogenesis by measuring the CD34-positive microvessel density. Low collagen XVIII expression by tumor hepatocytes was associated with large tumor size (r, -0.63; P < 0.001) and replacement of trabeculae with pseudoglandular-solid architecture (chi2, 28; P < 0.001), which indicate tumor progression. Tumors expressing the highest collagen XVIII levels were smaller and had lower microvessel density (P = 0.01) than those expressing moderate levels; and HCCs with the lowest collagen XVIII levels approached a plateau of microvessel density, which indicated that a decrease in collagen XVIII expression is associated with angiogenesis in primary liver cancer. HCCs recurring within 2 years of resection showed 2.2-fold lower collagen XVIII mRNA than nonrecurring ones (P = 0.02). The findings relied on the hepatocyte-specific long form. Thus, the endogenous expression of the endostatin precursor decreases along with tumor progression in HCCs.
Musso
O
O
Institut National de la Santé et de la Recherche Médicale U-456, Detoxication and Tissue Repair Unit, Université de Rennes 1, France.
Rehn
M
M
Théret
N
N
Turlin
B
B
Bioulac-Sage
P
P
Lotrian
D
D
Campion
J P
JP
Pihlajaniemi
T
T
Clément
B
B
D017398:Alternative Splicing; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D003094:Collagen / Q000096:biosynthesis*; D043170:Collagen Type XVIII; D018450:Disease Progression; D043169:Endostatins; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009389:Neovascularization, Pathologic / Q000378:metabolism; D010446:Peptide Fragments / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism
D043170:Collagen Type XVIII; D043169:Endostatins; D010446:Peptide Fragments; D012333:RNA, Messenger; D003094:Collagen