PTCH1+/− Dermal Fibroblasts Isolated from Healthy Skin of Gorlin Syndrome Patients Exhibit Features of Carcinoma Associated Fibroblasts

Alexandre Valin,Marie-Françoise Avril,Stéphanie Barnay-Verdier,Odile Chevallier-Lagente,Florence Brellier,Thomas Robert,Thierry Magnaldo,Hugues Ripoche

doi:10.1371/journal.pone.0004818

Abstract

Gorlin's or nevoid basal cell carcinoma syndrome (NBCCS) causes predisposition to basal cell carcinoma (BCC), the commonest cancer in adult human. Mutations in the tumor suppressor gene PTCH1 are responsible for this autosomal dominant syndrome. In NBCCS patients, as in the general population, ultraviolet exposure is a major risk factor for BCC development. However these patients also develop BCCs in sun-protected areas of the skin, suggesting the existence of other mechanisms for BCC predisposition in NBCCS patients. As increasing evidence supports the idea that the stroma influences carcinoma development, we hypothesized that NBCCS fibroblasts could facilitate BCC occurence of the patients. WT (n = 3) and NBCCS fibroblasts bearing either nonsense (n = 3) or missense (n = 3) PTCH1 mutations were cultured in dermal equivalents made of a collagen matrix and their transcriptomes were compared by whole genome microarray analyses. Strikingly, NBCCS fibroblasts over-expressed mRNAs encoding pro-tumoral factors such as Matrix Metalloproteinases 1 and 3 and tenascin C. They also over-expressed mRNA of pro-proliferative diffusible factors such as fibroblast growth factor 7 and the stromal cell-derived factor 1 alpha, known for its expression in carcinoma associated fibroblasts. These data indicate that the PTCH1+/− genotype of healthy NBCCS fibroblasts results in phenotypic traits highly reminiscent of those of BCC associated fibroblasts, a clue to the yet mysterious proneness to non photo-exposed BCCs in NBCCS patients.

Highlights

Non melanocytic skin cancers are the most prevailing cancers in human and 80 percent of them are basal cell carcinomas (BCCs) [1,2]
Whole genome microarray comparison of control and nevoid basal cell carcinoma syndrome (NBCCS) fibroblasts transcriptomes We compared the genome wide expression profile of 9 primary independent fibroblasts strains cultured in dermal equivalents (CTRL, n = 3; NBCCS, n = 6)
reverse transcription and quantitative polymerase chain reactions (RT-QPCR) confirmed the decreased average mRNA amounts of Collagen type 3 alpha 1 (COL3A1), collagen type 7 alpha 1 (COL7A1), and laminin alpha 2 (LAMA2) by 1.52, 1.72 and 2.33 respectively (p#0.05; p#0.05; p,0.025), in NBCCS compared to control fibroblasts (Table 2). Together these results indicate that some extracellular matrix (ECM) and basement membrane components are expressed differentially between NBCCS and control fibroblasts under organotypic culture conditions

Summary

Introduction

Non melanocytic skin cancers are the most prevailing cancers in human and 80 percent of them are basal cell carcinomas (BCCs) [1,2]. NBCCS is associated to a dramatic predisposition to BCCs (up to hundreds) [5]. In 1996, mutations in the tumor suppressor gene PATCHED (PTCH1) were found to be associated to NBCCS [6,7]. Most PTCH1 germinal mutations lead to premature stop codon [8], and in BCCs, are accompanied by somatic mutations or loss of heterozygosity (LOH) at the PTCH1 locus (9q22.3) [9,10], as expected for a tumor suppressor gene [11]. In sporadic BCCs somatic mutations in PTCH1 have been reported in up to 67% of cases; most of them correspond to ultraviolet fingerprints, CRT and CCRTT transitions [12–14]. Sporadic BCCs display frequent (93% cases) LOH of the PTCH1 locus [15,16]

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Results

Conclusion