Expression profiling of retinoblastoma and meibomian cell carcinoma using cDNA microarray. A. Kumar1, S.K. Dorairaj2, R. Prakash2, C.P. Venkatesh2, S. Chakraborty1. 1) MRDG, Indian Inst Science, Bangalore, India; 2) Minto Ophthalmic Hospital, Bangalore, India.
Development and progression of tumors is a multistep process dictated by expression of many genes. DNA microarray could facilitate identification of genes involved in tumor development by hybridizing cDNA samples from normal and tumor tissues on cDNA microarrays. Although it is well known that the loss-of-function of retinoblastoma protein causes retinoblastoma, it is not known as to how many other genes are involved in development and progression of retinoblastoma. Besides, the most common treatment available till date to treat retinoblastoma is enucleation of the affected eye(s). Therefore, finding targets for therapeutic intervention for retinoblastoma using microarray technique will be of paramount importance. Nothing is known about the genes involved in development and progression of meibomian cell carcinoma. The purpose of this study was to fill this gap using cDNA microarray technology. We have ascertained a total of 11 retinoblastoma (Rb) and five meibomian cell carcinoma (MCC) samples. We have also ascertained normal retina samples from eye globes which were discarded after removing cornea for corneal transplantation from individuals who donated their eyes. We have also collected normal eyelids from individuals who went through eyelid reconstruction surgery for a variety of reasons. We have isolated total RNAs from all of the retinoblastoma, meibomian cell carcinoma, normal retina and normal eyelid samples. We have analyzed three retinoblastoma samples using three 19K human microarray slides (University Health Network, Toronto). A comparison of the hybridization data showed up-regulation of 1,002 and down-regulation of 480 genes. Using semi-quantitative PCR, we have validated six genes so far. We have also carried out microarray analysis for two MCC tumors using human 8K microarray slides. Seventy genes were upregulated and 405 genes were downregulated. We have validated five genes so far in a panel of five MCC samples. The results will be presented and discussed. (Funding from ICMR, New Delhi is gratefully acknowledged).