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. 2022 May;51(5):429-435.
doi: 10.1111/jop.13299. Epub 2022 Apr 26.

Integrity and quantity of salivary cell-free DNA as a potential molecular biomarker in oral cancer: A preliminary study

Óscar Rapado-González  1   2   3 , José Luis López-Cedrún  4 , Ramón Manuel Lago-Lestón  2 , Alicia Abalo  2 , Guillermo Rubin-Roger  4 , Ángel Salgado-Barreira  5   6 , Rafael López-López  7 , Laura Muinelo-Romay  2   3 , María Mercedes Suárez-Cunqueiro  1   3   7
Affiliations

Integrity and quantity of salivary cell-free DNA as a potential molecular biomarker in oral cancer: A preliminary study

Óscar Rapado-González et al. J Oral Pathol Med. 2022 May.

Abstract

Background: Differences in cell-free DNA (cfDNA) fragments have been described as a valuable tool to distinguish cancer patients from healthy individuals. We aim to investigate the concentration and integrity of cfDNA fragments in saliva from oral squamous cell carcinoma (OSCC) patients and healthy individuals in order to explore their value as diagnostic biomarkers.

Methods: Saliva samples were collected from a total of 34 subjects (19 OSCC patients and 15 healthy controls). The total concentration of salivary cfDNA (scfDNA) was determined using a fluorometry method and quantitative real-time polymerase chain reaction (qPCR). To evaluate the scfDNA quantity and integrity, qPCR targeting Arthobacter luteus (ALU) sequences at three amplicons of different lengths (60, 115, and 247 bp, respectively) was carried out. ScfDNA integrity indexes (ALU115/ALU60 and ALU247/ALU60) were calculated as the ratio between the absolute concentration of the longer amplicons 115 bp and 247 bp and the total scfDNA amount (amplicon 60 bp).

Results: The total scfDNA concentration (ALU60) was higher in OSCC than in healthy donors, but this trend was not statistically significant. The medians of scfDNA integrity indexes, ALU115/ALU60 and ALU247/ALU60, were significantly higher in OSCC, showing area under the curve values of 0.8211 and 0.7018, respectively.

Conclusion: Our preliminary results suggest that scfDNA integrity indexes (ALU115/ALU60 and ALU247/ALU60) have potential as noninvasive diagnostic biomarkers for OSCC.

Keywords: ALU repeat; DNA integrity; liquid biopsy; oral squamous cell carcinoma (OSCC); saliva; salivary cell-free DNA (scfDNA).

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Conflict of interest statement

R. López‐López reports other from Nasasbiotech, during the conduct of the study; grants and personal fees from Roche, grants and personal fees from Merck, personal fees from AstraZeneca, personal fees from Bayer, personal fees, and nonfinancial support from BMS, personal fees from Pharmamar, personal fees from Leo, outside the submitted work. The rest of the authors have nothing to disclose.

Figures

FIGURE 1
FIGURE 1
ScfDNA integrity indexes in OCSCC patients and HC: (A) Ratio ALU115/ALU60 and (B) Ratio ALU247/ALU60. HC, healthy controls; OCSCC, oral cavity squamous cell carcinoma; scfDNA, salivary cell‐free DNA
FIGURE 2
FIGURE 2
Percentages of scfDNA fragments of different length ranging 60–115, 115–247, and ≥247 in OCSCC patients (red column) and HC (white columm). p < 0.05; **p < 0.01. HC, healthy controls; OCSCC, oral cavity squamous cell carcinoma; scfDNA, salivary cell‐free DNA
FIGURE 3
FIGURE 3
ROC curves of scfDNA integrity indexes ALU115/ALU60 and ALU247/ALU60 for discriminating OCSCC patients from HC. HC, healthy controls; OCSCC, oral cavity squamous cell carcinoma; ROC, receiver operating characteristic; scfDNA, salivary cell‐free DNA
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