Hyperexpression of low-density lipoprotein receptors and hydroxy-methylglutaryl-coenzyme A-reductase in human pinguecula and primary pterygium.
OBJECTIVE
There is now increasing evidence that pterygium and pinguecula are tumorlike tissues and that cell growth and DNA replication are closely linked to cholesterol metabolism. In this study, the expression of two main genes correlated to cholesterol metabolism--namely, the low-density lipoprotein receptor (LDL-R) gene and the hydroxy-methylglutaryl-coenzyme A-reductase (HMG-CoA-R) gene--were investigated in primary pterygium, pinguecula, and normal conjunctiva.


METHODS
Pterygium, pinguecula, and normal conjunctiva samples were obtained from 30 eyes (50% men) at the time of surgery. Total RNA extracted from the specimens was subjected to semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Equal amounts of total RNA were reverse transcribed into cDNA. The cDNA was subsequently amplified by the PCR in the presence of specific primers for low-density lipoprotein receptor (LDL-R) and for hydroxy-methylglutaryl coenzyme A reductase (HMG-CoA-R).


RESULTS
Semiquantitative RT-PCR analysis revealed that the mRNA levels of LDL-R and HMG-CoA-R were increased in pterygia, compared with levels in both pingueculae and normal conjunctivae. Differences were statistically significant (P <0.05), including pingueculae versus normal conjunctivae.


CONCLUSIONS
This study indicates that pterygium and pinguecula have an altered metabolism of cholesterol-namely increased LDL-R and HMG-CoA-R mRNAs-as is characteristic of tumorlike tissues, and that the high expression of LDL receptors renders them amenable to be treated by photodynamic therapy with intravenously injected verteporfin.
Peiretti
Enrico
E
Department of Surgical Sciences, Eye Clinic, University of Calgiri, Italy.
Dessì
Sandra
S
Putzolu
Marirosa
M
Fossarello
Maurizio
M
D002784:Cholesterol / Q000378:metabolism; D003229:Conjunctival Diseases / Q000378:metabolism*; D003240:Connective Tissue Diseases / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011625:Pterygium / Q000378:metabolism*; D012313:RNA / Q000302:isolation & purification; D012333:RNA, Messenger / Q000378:metabolism*; D011973:Receptors, LDL / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D012333:RNA, Messenger; D011973:Receptors, LDL; D012313:RNA; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases