Objective: EGFR is a receptor on the cell membrane with tyrosine-kinase activity and which is a regulator of proliferation, apoptosis, angiogenesis, tumor invasion. He is found to be overexpressed in some lung cancer histological subtypes. MEN1 is a tumor suppressor gene, with a role in cellular growth and differentiation, DNA reparation, and apoptosis. Method: Surgically resected specimen from 99 patients (men n=66; women n=33, age 57±11) with lung cancer were studied: carcinoid tumors (CT)-23, small cell lung carcinomas (SCLC)-13, large cell neuroendocrine carcinomas (LCNEC)-6, adenocarcinomas (AC)-29, and squamous cell carcinomas (SCC)-28. The histological subtype, pTNM stage, and gene expression of MEN1 and EGFR in tumor and normal lung tissue were evaluated. Results: Overexpression of EGFR was observed in 34 %(SCC-61 %, AC-31 %, SCLC-23 %, LCNEC-17 %, CT-13 %). Decreased expression was observed in 22 %(LCNEC-66 %, SCLC-54 %, CT-22 %, AC-14 %, SCC-7 %) (p<0.001). Overexpresssion of MEN1 was observed in 57 % of all tumors (SCLC-69 %, CT-65 %, SCC-57 %, LCNEC-50 %, AC-48 %) (p>0.05). Significant correlation between overexpression of MEN1 and early stage SCC was observed (p=0.03). Conclusion: EGFR is a target for therapy with monoclonal antibodies, so the tumors that overexpress EGFR can be considered for treatment with these drugs. MEN1 can eventually be a marker for good prognosis and a potential target for therapy. Objective: Homeobox genes encode transcription factors controlling cellular proliferation and differentiation. Altered expression of PROX1 homeobox gene is related to many cancers, including breast, esophagus, lymphatic and oral. Method: After overexpression of PROX1 gene in SCC9 cell line, total RNA was extracted from three overexpressing-PROX1 clones (OC) and one control-transfection cell clone (CC). Microarray analyses were performed using the Whole Human Genome 44 K according to the manufacturer's instructions. Genes with a fold change of greater or lower than 2.0 in OC versus CC, were considered as increased or decreased, respectivelly. Gene Ontology (GO) was used to assign biological process related to significantly differentially expressed genes. Results: Down-regulated genes MMP2, TIMP3 and NOTCH1 were further validated by qRT-PCR. Comparative gene analysis of OC and CC revealed 925 up-regulated and 789 down-regulates genes. Pathways induced upon PROX1 overexpression in GO terms included vascular development control, cellular adhesion, regulation of proliferation, among others. MMP2, TIMP3 and NOTCH1 expression by qRT-PCR showed reduced expression leves in OC. These genes are commonly overexpressed in oral squamous cell carcinoma and have been related with metastatic tumors and worse prognosis. Objective: Barrett´s Esophagus is the unique known precursor for esophageal adenocarcinoma (EAC), in a gradual progression to dysplasia. Our objective is to determine the correlation between the hypermethylation in CpG islands of the promoter region of p16 tumoral suppressor gen in epithelial DNA and the histopathological pattern, as possible biomarker for risk of progression. Method: 1. A study was performed about the evolution of precursor lesions, in a group of 55 patients diagnosed following the Vienna classification. 2. p16 hypermethylation is analyzed in paraffin embedding samples, through laser microdissection, DNA extraction, PCR amplification, pyrosequencing and quantification. Results: 1.14 of 20 cases with 2 to 5 biopsies remained as ND, ID or LGD, and 6 cases progressed to HGD and/or EAC. 2. Within the control group the methylation grade is 6.53 % and in the diagnostic groups is 12.04 % (ND), 7 % (ID), 17.05 % (LGD), 8.50 % (HGD) and 23.33 % (EAC).