Liétard J, Loréal O, Théret N, Campion J P, L'Helgoualc'h A, Turlin B, Ramée M P, Yamada Y, Clément B
Unité Détoxication et Réparation Tissulaire INSERM U-456, Rennes, France.
J Hepatol. 1998 Apr;28(4):691-9. doi: 10.1016/s0168-8278(98)80294-8.
BACKGROUND/AIMS: Laminins, the major non-collagenous basement membrane components, are involved in various biological processes. Laminin isoforms have never been characterized in human livers. The expression of five laminin mRNA was investigated in livers with or without cancer and in hepatoma cells and, by comparison, in both rat hepatoma and hepatic stellate cells.
Laminin alpha1, alpha2, beta1, beta2 and gamma1 mRNA was detected by northern blot and/or RT-PCR in livers without chronic disease (n=5), in both tumoral and non-tumoral areas of livers with hepatocellular carcinomas (n=13) or metastases (n=18), in human HBGC2 and rat Faza-567 hepatoma cell lines, and in 6-day-old rat hepatic stellate cell cultures.
Laminin alpha1, alpha2 and beta1 mRNA were found in 25-33% and gamma1 mRNA in 58% of the livers, the signal for laminin beta2 mRNA being faint in all the samples. Laminin alpha2, beta1, beta2 and gamma1 mRNA were expressed in hepatoma and stellate cells. The laminin alpha2 cDNA probe recognized a 3.5 kb mRNA different from the expected 9 kb mRNA. Using degenerated oligonucleotides, RT-PCR products from both rat hepatoma and stellate cells revealed 90% identity with the alpha2 chain sequence. Antibodies against peptide deduced from the conserved C-terminal domain of both alpha1 and alpha2 chains recognized polypeptides corresponding to the degradation products of alpha2 chain in liver extracts and both media and cell layers from hepatoma and stellate cells. In addition, a Mr=130000 polypeptide was revealed by these antibodies in liver extracts and cell layers, which was consistent with the expected size deduced from the 3.5 kb mRNA.
This first report on laminin isoforms in human livers indicates that laminin 1 (alpha1-beta1-gamma1), 2 (alpha2-beta1-gamma1), 3 (alpha1-beta2-gamma1) and 4 (alpha2-beta2-gamma1) mRNA and a polypeptide homologous to the alpha2 isoform, which could correspond to a truncated form of this chain, are usually expressed in non-tumoral and/or tumoral livers.
背景/目的：层粘连蛋白是基底膜的主要非胶原蛋白成分，参与多种生物学过程。层粘连蛋白异构体在人类肝脏中尚未得到鉴定。本研究检测了五种层粘连蛋白mRNA在有癌或无癌肝脏、肝癌细胞中的表达情况，并与大鼠肝癌细胞和肝星状细胞进行了比较。
采用Northern印迹法和/或逆转录-聚合酶链反应（RT-PCR）检测了5例无慢性疾病肝脏、13例肝细胞癌（HCC）或18例转移癌肝脏的肿瘤及非肿瘤组织、人HBGC2和大鼠Faza-567肝癌细胞系以及6日龄大鼠肝星状细胞培养物中层粘连蛋白α1、α2、β1、β2和γ1 mRNA的表达。
在25% - 33%的肝脏中检测到层粘连蛋白α1、α2和β1 mRNA，58%的肝脏中检测到γ1 mRNA，所有样本中层粘连蛋白β2 mRNA信号均较弱。层粘连蛋白α2、β1、β2和γ1 mRNA在肝癌细胞和星状细胞中均有表达。层粘连蛋白α2 cDNA探针识别出一条3.5 kb的mRNA，与预期的9 kb mRNA不同。使用简并寡核苷酸，大鼠肝癌细胞和星状细胞的RT-PCR产物与α2链序列的同源性为90%。抗α1和α2链保守C末端结构域推导肽段的抗体识别肝提取物、肝癌细胞和星状细胞培养基及细胞层中与α2链降解产物相对应的多肽。此外，这些抗体在肝提取物和细胞层中还检测到一条Mr = 130000的多肽，与3.5 kb mRNA推导的预期大小一致。
本研究首次报道了人类肝脏中层粘连蛋白异构体的情况，表明层粘连蛋白1（α1-β1-γ1）、2（α2-β1-γ1）、3（α1-β2-γ1）和4（α2-β2-γ1）mRNA以及与α2异构体同源的一种多肽（可能是该链的截短形式）通常在非肿瘤和/或肿瘤肝脏中表达。
