Expression analysis of the mouse S100A7/psoriasin gene in skin inflammation and mammary tumorigenesis

BACKGROUND: The human psoriasin (S100A7) gene has been implicated in inflammation and tumor progression. Implementation of a mouse model would facilitate further investigation of its function, however little is known of the murine psoriasin gene. In this study we have cloned the cDNA and characterized the expression of the potential murine ortholog of human S100A7/psoriasin in skin inflammation and mammary tumorigenesis. METHODS: On the basis of chromosomal location, phylogenetic analysis, amino acid sequence similarity, conservation of a putative Jab1-binding motif, and similarities of the patterns of mouse S100A7/psoriasin gene expression (measured by RT-PCR and in-situ hybridization) with those of human S100A7/psoriasin, we propose that mouse S100A7/psoriasin is the murine ortholog of human psoriasin/S100A7. RESULTS: Although mouse S100A7/psoriasin is poorly conserved relative to other S100 family members, its pattern of expression parallels that of the human psoriasin gene. In murine skin S100A7/psoriasin was significantly upregulated in relation to inflammation. In murine mammary gland expression is also upregulated in mammary tumors, where it is localized to areas of squamous differentiation. This mirrors the context of expression in human tumor types where both squamous and glandular differentiation occur, including cervical and lung carcinomas. Additionally, mouse S100A7/psoriasin possesses a putative Jab1 binding motif that mediates many downstream functions of the human S100A7 gene. CONCLUSION: These observations and results support the hypothesis that the mouse S100A7 gene is structurally and functionally similar to human S100A7 and may offer a relevant model system for studying its normal biological function and putative role in tumor progression

A Top panel Expression of mouse S100A7/psoriasin in normal skin RNA from normal mouse skin from 6 different animals (1–6) was subjected to RT-PCR analysis using mouse psoriasin-ORF primers and β-actin primers as described in Materials and Methods

<p><b>Copyright information:</b></p><p>Taken from "Expression analysis of the mouse S100A7/psoriasin gene in skin inflammation and mammary tumorigenesis"</p><p>BMC Cancer 2005;5():17-17.</p><p>Published online 17 Feb 2005</p><p>PMCID:PMC553966.</p><p>Copyright © 2005 Webb et al; licensee BioMed Central Ltd.</p> PCR products of 344 bp for mouse S100A7/psoriasin and 330 bp for β-actin are shown. Bottom panel Expression of mouse S100A7/psoriasin in normal mouse mammary gland) and DMB A induced mammary tumors RNA from freshly frozen matched normal mammary gland (Normal MG) and DMBA induced mammary tumors (MG tumor) from 6 different CD1 mice (1–6) was extracted and subjected to RT-PCR analysis using mouse psoriasin-ORF primers and β-actin primers as described in Materials and Methods. PCR products of 344 bp for mouse S100A7/psoriasin and 330 bp for β-actin are shown. B Semi-quantitative analysis of the results shown in bottom panel of A Data points represent the means of three independent PCR reactions. The value of mouse S100A7 normalized to β-actin for each matched normal MG and MG tumor sample are joined by red lines. Blue lines represent the median value of mouse S100A7/psoriasin expression for each tissue type. Increased expression in MG tumors is significant (p < 0.05, one sided Wilcoxon signed rank test)