title: Papillary and follicular thyroid carcinomas show distinctly different microarray expression profiles and can be distinguished by a minimum of five genes.
abstract: OBJECTIVE
  We have previously conducted independent microarray expression analyses of the two most common types of nonmedullary thyroid carcinoma, namely papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC). In this study, we sought to combine our data sets to shed light on the similarities and differences between these tumor types.
  
  
  METHODS
  Microarray data from six PTCs, nine FTCs, and 13 normal thyroid samples were normalized to remove interlaboratory variability and then analyzed by unsupervised clustering, t test, and by comparison of absolute and change calls. Expression changes in four genes not previously implicated in thyroid carcinogenesis were verified by reverse transcriptase polymerase chain reaction on these same samples, together with eight additional FTC tumors.
  
  
  RESULTS
  PTCs showed two distinct groups of genes that were either over- or underexpressed compared with normal thyroid, whereas the predominant changes in FTCs were of decreased expression. Five genes could collectively distinguish the two tumor types. PTCs showed overexpression of CITED1, claudin-10 (CLDN10), and insulin-like growth factor binding protein 6 (IGFBP6) but showed no change in expression of caveolin-1 (CAV1) or -2 (CAV2); conversely, FTCs did not express CLDN10 and had decreased expression of IGFBP6 and/or CAV1 and CAV2.
  
  
  CONCLUSIONS
  PTC and FTC show distinctive microarray expression profiles, suggesting that either they have different molecular origins or they diverge distinctly from a common origin. Furthermore, if verified in a larger series of tumors, these genes could, in combination with known tumor-specific chromosome translocations, form the basis of a valuable diagnostic tool.
authors.affiliation: Human Cancer Genetics Program, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Micheala A
authors.initials: MA
authors.lastname: Aldred
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Sandya
authors.initials: S
authors.lastname: Liyanarachchi
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Pellegata
authors.forename: Oliver
authors.initials: O
authors.lastname: Gimm
authors.forename: Sissy
authors.initials: S
authors.lastname: Jhiang
authors.forename: Ramana V
authors.initials: RV
authors.lastname: Davuluri
authors.forename: Albert
authors.initials: A
authors.lastname: de la Chapelle
authors.forename: Charis
authors.initials: C
authors.lastname: Eng
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000235:genetics*; D014408:Biomarkers, Tumor / Q000235:genetics; D002291:Carcinoma, Papillary / Q000235:genetics*; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D013961:Thyroid Gland; D013964:Thyroid Neoplasms / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor