RESUMO
Improving poor outcomes in patients with pancreatic cancer requires a greater understanding of the biological mechanisms contributing to radioresistance. We, therefore, sought to identify genes involved in the radioresistance of pancreatic cancer cells. Two pancreatic cancer cell lines, CFPAC-1 and Capan-1, were repeatedly exposed to radiation, establishing two radioresistant cell lines. Gene expression profiling using cDNA microarrays was performed to identify genes responsible for radioresistance. The levels of expression of mRNAs encoded by selected genes and their correlation with radiation dose resulting in 50% survival rate were analyzed in pancreatic cancer cell lines. The radiation dose resulting in a 50% survival rate was significantly higher in irradiated (IR) compared to parental CFPAC-1 cells (8.31 ± 0.85 Gy vs. 2.14 ± 0.04 Gy, P<0.0001), but was lower in IR compared with parental Capan-1 cells (2.66 ± 0.24 Gy vs. 2.25 ± 0.03 Gy, P=0.04). cDNA microarray analysis identified 4 genes, including S100 calcium binding protein A4 (S100A4), overexpressed and 23 genes underexpressed in the IR compared with the parental cell lines. The levels of S100A4 mRNA expression were correlated with radiation dose resulting in a 50% survival rate (Pearson's test, R2=0.81, P=0.0025). S100A4 mRNA expression may predict radioresistance of pancreatic cancer cells and may play an important role in the poor response of pancreatic cancer cells to radiation therapy.
Assuntos
Neoplasias Pancreáticas/radioterapia , Tolerância a Radiação/genética , Proteínas S100/genética , Proteínas S100/efeitos da radiação , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Perfilação da Expressão Gênica , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias Pancreáticas/genética , RNA Mensageiro/biossíntese , Proteína A4 de Ligação a Cálcio da Família S100 , Proteínas S100/biossíntese , Proteínas S100/metabolismoAssuntos
Biomarcadores Tumorais/metabolismo , Melanoma/diagnóstico , Fatores de Crescimento Neural/metabolismo , Proteínas S100/metabolismo , Neoplasias Cutâneas/diagnóstico , Raios Ultravioleta , Biomarcadores Tumorais/efeitos da radiação , Humanos , Melanócitos/metabolismo , Melanócitos/efeitos da radiação , Fatores de Crescimento Neural/efeitos da radiação , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/efeitos da radiaçãoRESUMO
Ultraviolet B (UVB) radiation has been shown to induce significant alterations in both function and surface antigen expression of epidermal Langerhans cells (ELC). In this study we investigated the effect of UVB radiation on ELC marker S-100 protein antigen (S-100 Ag) which is present in the nucleus and cytoplasm of human ELC. A total of 34 sites on 31 volunteers were exposed to 3 MED (minimal erythema dose) of UVB and biopsied at various times up to 7 days after irradiation. Skin from 9 noninjured and 7 slice-wounded subjects served as controls. The avidin-biotin-peroxidase staining technique was used to identify S-100 Ag in sections of formalin-fixed, paraffin-embedded tissue, and the numbers of stained suprabasal dendritic cells were then counted over a 200 basal cell length of interfollicular epidermis. Noninjured skin had 3.56 +/- 3.01 cells, whereas slice-wounded skin had elevated numbers (greater than 10.0 cells) at 1, 24, and 48 h after injury. Following UVB irradiation, a significant (p less than 0.001) increase in antigen-positive cells (14 +/- 3.46) was found at 1 h; this number declined to just below normal at 12 h, but by 48 h returned to and remained at preinjury levels. In contrast to previous observations of the depletion of ELC surface markers by UVB radiation, we demonstrate here that the numbers of S-100 Ag-positive ELC actually increase following comparable doses of radiation. Since this increase occurs so rapidly following both UVB irradiation and slice injury, S-100 Ag may be synthesized or unmasked within the ELC as a response to wounding of the epidermis.
