title: Expression of various insulin-like growth factor-1 mRNA isoforms in colorectal cancer.
abstract: OBJECTIVE
  Several epidemiological studies have attempted to demonstrate a relationship between increased serum level of insulin-like growth factor 1 (IGF-1) and an augmented risk of developing colorectal cancers (CRC). The human IGF-1 gene is composed of 6 exons and demonstrated expression of 6 different splice variants (isoforms) of mRNA (IA, IB, IC, IIA, IIB and IIC). The aim of the study was to evaluate the expression of different isoforms of IGF-1 mRNA in CRC and normal colon tissue.
  
  
  METHODS
  13 paired tissue specimens (colorectal tumor and non-tumor tissues) were analyzed using both quantitative polymerase chain reaction (PCR) and immunocytochemistry methods (IHC). The expression of classes I and II and variants A, B, C of IGF-1 mRNA were measured.
  
  
  RESULTS
  In CRC higher amounts of IGF-1 class II mRNA than class I mRNA were detected. Among A, B, C isoforms, A variant of IGF-1 mRNA prevailed. The amounts of IGF-1 class I and class II mRNAs and of IGF-1 variant B mRNA were lowered in CRC as compared to the control. In CRC significant correlations were detected between reciprocal expression of class I and class II as well as between I and II isoforms and A, B and C.
  
  
  CONCLUSIONS
  Expression of IGF-1 mRNA isoforms differs between normal and CRC tissues. Even if all isoforms of IGF-1 mRNA manifested correlations with each other in tissues of CRC, expression of all transcripts (except that of isoform A) was significantly decreased as compared to the control.
authors.affiliation: Department of Histology and Embryology, Poznan University of Medical Sciences.
authors.forename: Aldona
authors.initials: A
authors.lastname: Kasprzak
authors.forename: Witold
authors.initials: W
authors.lastname: Szaflarski
authors.forename: Jacek
authors.initials: J
authors.lastname: Szmeja
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Andrzejewska
authors.forename: Wiesława
authors.initials: W
authors.lastname: Przybyszewska
authors.forename: Maria
authors.initials: M
authors.lastname: Koczorowska
authors.forename: Michał
authors.initials: M
authors.lastname: Drews
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Kaczmarek
keywords: IGF-1 isoforms; QPCR; colorectal carcinoma; immunocytochemistry