title: Isolation and sequencing of a novel tropomyosin isoform preferentially associated with colon cancer.
abstract: OBJECTIVE
  Nonmuscle human tropomyosin (hTM) isoforms have distinct functions and may play important roles in various disease processes.
  
  
  METHODS
  In an attempt to identify colon epithelial tropomyosin isoform, a complementary DNA library prepared from a human colon cancer cell line T84 was screened by an oligonucleotide probe complementary to messages of all known hTM isoforms. A novel clone called TC22 was obtained. The amino acid sequence of TC22 isoform is identical to isoform 5 (hTM5) apart from the C terminal domain, amino acids 222-247 coding the exon 9.
  
  
  RESULTS
  Northern blot analysis showed that TC22 message is expressed in transformed epithelial cell lines and tumor tissues but not in normal epithelial cells. We developed a monoclonal antibody specific to TC22 isoform (TC22-4). By Western blot and immunoperoxidase assays, we analyzed 105 colonic specimens (fresh frozen and formalin fixed) from 96 patients with colon polyps (hyperplastic) or adenomas with or without dysplasia and cancer. Twenty-one of 22 (95%) of colon cancer specimens showed the presence of TC22, compared with only 1 of the 17 normal colon specimens and none of the 13 hyperplastic polyps (P < 0.0001). As assayed by immunoperoxidase staining, TC22 expression progressively increased in benign adenomatous polyps (35%) and polyps with mild and severe dysplasia (57% and 100%, respectively).
  
  
  CONCLUSIONS
  We cloned and sequenced a novel hTM isoform, TC22, which is strongly associated with colonic neoplasia and carcinoma. TC22 may provide a useful biomarker for surveillance of colon cancer.
authors.affiliation: Department of Biological Sciences, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Jenny L-C
authors.initials: JL
authors.lastname: Lin
authors.forename: Xin
authors.initials: X
authors.lastname: Geng
authors.forename: Sangeeta Das
authors.initials: SD
authors.lastname: Bhattacharya
authors.forename: Jae-Ran
authors.initials: JR
authors.lastname: Yu
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Reiter
authors.forename: Bhagyalakshmi
authors.initials: B
authors.lastname: Sastri
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Glazier
authors.forename: Zafar K
authors.initials: ZK
authors.lastname: Mirza
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Wang
authors.forename: Peter S
authors.initials: PS
authors.lastname: Amenta
authors.forename: Kiron M
authors.initials: KM
authors.lastname: Das
authors.forename: Jim J-C
authors.initials: JJ
authors.lastname: Lin
mesh_terms: D000236:Adenoma / Q000235:genetics* / Q000378:metabolism; D018256:Adenomatous Polyps / Q000378:metabolism; D000595:Amino Acid Sequence / Q000235:genetics; D001483:Base Sequence / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D003106:Colon / Q000378:metabolism; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism; D003111:Colonic Polyps / Q000378:metabolism / Q000473:pathology; D018076:DNA, Complementary / Q000235:genetics; D004274:DNA, Recombinant; D014644:Genetic Variation; D006801:Humans; D007124:Immunoenzyme Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D012016:Reference Values; D014335:Tropomyosin / Q000235:genetics* / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D004274:DNA, Recombinant; D009363:Neoplasm Proteins; D014335:Tropomyosin