Abstract
Purpose: :
Pterygium is a fibrovascular overgrowth from the conjunctiva onto the cornea. However, after surgical removal there is often a high recurrence rate. The aim of this study was to determine differential gene expression associated with recurrent pterygium.
Methods: :
We have separately analysed primary and recurrent pterygium tissues as well as uninvolved conjunctiva tissue frozen immediately after surgical removal. Eight primary pterygium tissues, 3 recurrent pterygium tissues and 4 pools of conjunctiva (4 conjunctiva/pool) were used for extraction of total RNA and hybridization to the human genome U133A Genechip (Affymetrix Inc.). The RMA algorithm was applied to extract information from the image file. Determination of significant genes was by t–test with p<0.05 level and with a fold change more than 2.
Results: :
Multiple group comparisons of the microarray data revealed that a total of 470 probe sets were differentially expressed. Sixty probe sets were differentially regulated in primary pterygium compared to conjunctiva, 395 probe sets were significantly changed when comparing the recurrent to conjunctiva and 298 probe sets were differentially regulated in recurrent when compared to primary pterygium. Genes commonly down regulated in both primary and recurrent pterygium included ATF3, BTG2, IGFBP3, FosB and Jun and up regulated genes included CD24, MUC5AC, SERPINB13 and keratin 6a. Genes significantly up regulated in only the primary pterygium include ß–microseminoprotein (MSMB), melan–A (MLANA) and CEACAM5. On the other hand, genes specifically up–regulated in recurrent pterygium included CDC25a, CDC2 and PAQR4.
Conclusions: :
It is suggested that environmental factors may lead to damage of ocular surface cells triggering a wound response and a protective cellular response. If this challenge is not diminished it may result in the transformation of cells into a stage characterized by the abnormal growth seen as a pterygium. Funded by BMRC 03/1/35/19/231 and NMRC IBG.
Keywords: Pterygium • gene microarray