Genomic DNA Copy Number Aberrations, Histological Diagnosis, Oral Subsite and Aneuploidy in OPMDs/OSCCs.

Patrizio Castagnola,Walter Giaretti,Davide Malacarne,David Brown,Monica Pentenero,Sergio Gandolfo,Roberto Marino,Cinzia Aiello,Gabriella Cirmena,Massimo Maffei,Massimiliano Monticone,Gabriele Zoppoli,Lars Kaderali

doi:10.1371/journal.pone.0142294

Abstract

Oral potentially malignant disorders (OPMDs) characterized by the presence of dysplasia and DNA copy number aberrations (CNAs), may reflect chromosomal instability (CIN) and predispose to oral squamous cell carcinoma (OSCC). Early detection of OPMDs with such characteristics may play a crucial role in OSCC prevention. The aim of this study was to explore the relationship between CNAs, histological diagnosis, oral subsite and aneuploidy in OPMDs/OSCCs. Samples from OPMDs and OSCCs were processed by high-resolution DNA flow cytometry (hr DNA-FCM) to determine the relative nuclear DNA content. Additionally, CNAs were obtained for a subset of these samples by genome-wide array comparative genomic hybridization (aCGH) using DNA extracted from either diploid or aneuploid nuclei suspension sorted by FCM. Our study shows that: i) aneuploidy, global genomic imbalance (measured as the total number of CNAs) and specific focal CNAs occur early in the development of oral cancer and become more frequent at later stages; ii) OPMDs limited to tongue (TNG) mucosa display a higher frequency of aneuploidy compared to OPMDs confined to buccal mucosa (BM) as measured by DNA-FCM; iii) TNG OPMDs/OSCCs show peculiar features of CIN compared to BM OPMDs/OSCCs given the preferential association with total broad and specific focal CNA gains. Follow-up studies are warranted to establish whether the presence of DNA aneuploidy and specific focal or broad CNAs may predict cancer development in non-dysplastic OPMDs.

Highlights

Oral cancer is often diagnosed at a late stage and as a result is characterized by poor prognosis
When we tested the hypothesis that the occurrence of DNA aneuploidy differed between tongue (TNG) and buccal mucosa (BM) oral potentially malignant disorders (OPMDs)/oral squamous cell carcinomas (OSCCs), we found that the proportion of DNA aneuploidy was higher in ND-OPMDs limited to TNG mucosa compared to ND-OPMDs limited to the BM (P = 3.6 E-03, OR 4.9, CI 1.6–15.2, q = 1.3E-02) and in dysplastic OPMD (D-OPMD)/OSCC limited to the TNG mucosa compared to D-OPMD/OSCC limited to the BM (P = 6.6E-03, OR 5.7, CI 1.4–24, q = 1.3E-02) (Fig 2A)
The absence or presence of these copy number aberrations (CNAs) versus ploidy status (DI = 1 or DNA index (DI) 61⁄4 1) and versus histology (ND-OPMD or D-OPMDs/OSCCs) were evaluated by 2 by 2 contingency table analysis. By using this approach we found that 6 CNAs were associated with DNA aneuploidy and 2 CNAs were associated with a DNA diploid status in ND-OPMDs (Table 3), whereas in D-OPMDs/OSCCs, 21 CNAs were associated with DNA aneuploidy and none with DNA diploid status (Table 3)