ABSTRACT: The purpose of this study is to search for aberrant genes in HaCaT keratinocytes after chronic exposure to arsenic trioxide. The objective of the investigation was to discover the mechanism of arsenic carcinogenicity in human epidermal keratinocytes. We hypothesize that a combined strategy of DNA microarray, qRT-PCR and gene function annotation will identify aberrantly expressed genes in HaCaT keratinocyte cell line after chronic treatment with arsenic trioxide. HaCaT cells were chronically exposed to 0.5M-BM-5g/mL arsenic trioxide (As2O3) up to 22 passages and RNA was extracted. Microarray data analysis identified 14 up-regulated genes and 21 down-regulated genes in response to arsenic trioxide Two experimental groups: 1. The treatment group was sub-cultured up to passage 22 to establish a chronic exposure state. 2. The passage control group was also sub-cultured up to 22 passages but with no exposure to arsenic trioxide. 4 technical replicates with 3 replicates making a total of 8X3 =24 samples HaCat Cell untreated (passage control): 1. H1_H001, H1_H002, H1_H003 2. H2_ H004, H2_H005, H2_H006 3. H3_ H007, H3_H008, H3_H009 4. H4_ H010, H4_H011, H4_H012 HaCat Cell treated with 0.5M-BM-5g/ml of arsenic trioxide: 5. A1_H013, A1_H014, A1_H015 6. A2_H016, A2_H017, A2_H018 7. A3_H019, A3_H020, A3_H021 8. A4_H022, A4_H023, A4_H024 Cell Type: Human Skin Keratinocyte: 1.5 M-CM-^W105 HaCaT cells were cultured in 7.5 ml of complete DMEM containing 10% Fetal Bovine Serum (FBS) and 1% penicillin, streptomycin in T-25 culture plate. Cells were incubated in a humidified atmosphere with 5% CO2 at 37 M-BM-:C. The treatment groups were exposed to 0.5M-BM-5g/mL As2O3 (equivalent to LC 0.5), and passaged at 90% confluent. Total RNA was extracted from 4 technical replicates of unexposed HaCaT cells and HaCaT cells chronically exposed to arsenic trioxide up to passage 22 using RNA STAT-60 (TEL-TEST, INC, Friendswood, TX, USA).
