AIM:To identify the altered gene expression patterns insquamous cell carcinoma of esophagus(ESCC)in relationto adjacent normal esophageal epithelium.METHODS:Total RNA was extracted using SV total RNAisolation kit from snap frozen tissues of ESCC samples andnormal esophageal epithelium far from the tumor.Radio-labeled cDNA were synthesized from equal quantities oftotal RNAs of tumor and normal tissues using combinationsof 24 arbitrary 13-mer primers and three differentanchoring oligo-dT primers and separated on sequencinggels.cDNA with considerable different amounts of signalsin tumor and normal tissue were reamplified and cloned.Using southern blot,the clones of each band were controlledfor false positive results caused by probable heterogeneityof cDNA population with the same size.Clones thatconfirmed differential expression by slot blot selected forsequencing and northern analysis.Corresponding full-lengthgene sequences was predicted using human genomeproject data,related transcripts were translated and usedfor various protein/motif searches to speculate theirprobable functions.RESULTS:The 97 genes showed different levels of cDNAin tumor and normal tissues of esophagus.The expressionof real gene was remarkably down regulated in all 10surveyed tumor tissues.Akrlc2,a member of the aldo-keto reductase 1C family,which is involved in metabolismof sex hormones and xenobiotics,was up-regulated in 8out of 10 inspected ESCC samples.Rablla,RPL7,andRPL28 showed moderate levels of differential expression. Many other cDNAs remained to further studies.CONCLUSION:The mal gene which is switched-off in allESCC samples can be considered as a tumor suppressorgene that more studies in its regulation may lead to valuableexplanations in ESCC development.Akr1c2 which is up-regulated in ESCC probably plays an important role in tumordevelopment of esophagus and may be proposed as apotential molecular target in ESCC treatments.Differentialdisplay technique in spite of many disadvantages is still avaluable technique in gene function exploration studies tofind new candidates for improved ones like gene chips. AIM: To identify the altered gene expression patterns insquamous cell carcinoma of esophagus (ESCC) in relation to adjacent normal esophageal epithelium. METHODS: Total RNA was extracted using SV total RNAisolation kit from snap frozen tissues of ESCC samples and normal esophageal epithelium far from the tumor. Radio-labeled cDNA was synthesized from equal quantities of total RNAs of tumor and normal tissues using combinations of 24 arbitrary 13-mer primers and three different anchoring oligo-dT primers and separated on sequencing genes. CDNA with considerable different amounts of signals in tumor and normal tissue were reamplified and cloned. Southern blot, the clones of each band were controlled for false positive results caused by probable heterogeneity of cDNA population with the same size. Clones that confirmed differential expression by slot blot selected forsequencing and northern analysis. Resolution full-length gene sequences was predicted using human genome project data, related transcripts were translated and used for various protein / motif searches to speculate their proficiency functions .RESULTS: The 97 genes showed different levels of cDNAin tumor and normal tissues of esophagus. expression of real genes were remarkably down regulated in all 10 surveyed tumor tissues. Akrlc2, a member of the aldo-keto reductase 1C family, which is involved in metabolism of sex hormones and xenobiotics, was up-regulated in 8 out of 10 inspected ESCC samples. Ribella, RPL7, and RPL28 showed moderate levels of differential expression. CONCLUSION: The mal gene which is switched-off in all ESCC samples can be considered as a tumor suppressor gene that more studies in its regulation may lead to valuable plans in ESCC development. Akr1c2 which is up-regulated in ESCC probably plays an important role in tumor development esophagus and may be proposed as apotential molecular target in ESCC treatments. Differential display technique in spite of many deficiencies is still avaluable technique in gene function exploration studies tofind new candidates for improved ones like gene chips.