Hypomethylation of the DNMT3L promoter in ocular surface squamous neoplasia.
BACKGROUND
Cancer is known to have epigenetic inputs, with events like genomewide hypomethylation and gene-specific hypermethylation of DNA. The DNA methyltransferase enzymes act as effectors of this reprogramming. A previous study revealed that hypomethylation at the DNA methyltransferase 3-like (DNMT3L) promoter could be a potential biomarker in cervical tumors. Because the pathobiology of ocular surface squamous neoplasia (OSSN) is similar to that of cervical tumors, we wanted to determine whether similar changes occur in the methylation pattern at the DNMT3L promoter in OSSN.


OBJECTIVE
To evaluate the methylation status of the DNMT3L promoter in OSSN compared with healthy conjunctiva.


METHODS
We evaluated DNA methylation at the DNMT3L promoter in the tumor tissues of 6 patients with histologically proven OSSN and in healthy conjunctiva tissue from 7 individuals for controls using the sodium bisulfite-assisted conversion of genomic DNA. Extracted genomic DNA was treated with sodium bisulfite and amplified with specific primers for the DNMT3L promoter region. The specific polymerase chain reaction products were cloned and sequenced.


RESULTS
The mean age of these patients was 50.2 years (range, 35-65 years). Histologically, 4 OSSN cases were invasive; 2 were intraepithelial. Healthy conjunctival tissues exhibited a methylated promoter region, whereas a variable loss of methylation was observed in all 6 OSSN cases.


CONCLUSIONS
We have, for the first time to our knowledge, identified loss of methylation at the DNMT3L promoter in OSSN cases, but its physiologic significance is yet to be understood. Further studies are warranted to substantiate our results.
Manderwad
Guru Prasad
GP
Ophthalmic Pathology Services, Kallam Anji Reddy Campus, L. V. Prasad Eye Institute, Hyderabad, India.
Gokul
Gopinathan
G
Kannabiran
Chitra
C
Honavar
Santosh G
SG
Khosla
Sanjeev
S
Vemuganti
Geeta K
GK
D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D003230:Conjunctival Neoplasms / Q000235:genetics* / Q000473:pathology; D003316:Corneal Diseases / Q000235:genetics* / Q000473:pathology; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D019175:DNA Methylation; D020868:Gene Silencing; D006801:Humans; D008875:Middle Aged; D010865:Pilot Projects
C412484:DNMT3L protein, human; D004248:DNA (Cytosine-5-)-Methyltransferases