Analysis of Saliva Gene Expression during Head and Neck Cancer Radiotherapy: A Pilot Study

Abstract

Saliva, a biological fluid, is a promising candidate for novel approaches to prognosis, clinical diagnosis, monitoring and management of patients with both oral and systemic diseases. However, to date, saliva has not been widely investigated as a biomarker for radiation exposure. Since white blood cells are also present in saliva, it should theoretically be possible to investigate the transcriptional biomarkers of radiation exposure classically studied in whole blood. Therefore, we collected whole blood and saliva samples from eight head and neck cancer patients before the start of radiation treatment, at mid-treatment and after treatment. We then used a panel of five genes: BAX, BBC3, CDKN1A, DDB2 and MDM2, designated for assessing radiation dose in whole blood to evaluate gene expression changes that can occur during radiotherapy. The results revealed that the expression of the five genes did not change in whole blood. However, in saliva, CDKN1A and DDB2 were significantly overexpressed at the end, compared to the start, of radiotherapy, and MDM2 was significantly underexpressed between mid-treatment and at the end of treatment. Interestingly, CDKN1A and DDB2 expressions also showed an increasing monotonic relationship with total radiation dose received during radiotherapy. To our knowledge, these results show for the first time the ability to detect gene expression changes in saliva after head and neck cancer radiotherapy, and pave the way for further promising studies validating saliva as a minimally invasive means of biofluid collection to directly measure radiation dose escalation during treatment.

Candidate gene biodosimetry markers of exposure to external ionizing radiation in human blood: A systematic review

“…Finally, this review focused on the expression of protein-coding genes in blood, but some studies also investigated other types of radiation biomarkers or other biofluids. Thus, gene expression changes in saliva have been assessed during radiation treatment for head and neck cancer [ 78 ]. Radiation-induced changes in non-coding RNAs such as miRNAs or recently discovered lncRNAs have also been investigated as potential radiation dosimetry biomarkers [ 79 – 84 ].…”

Salivary Biomarkers for Oral Squamous Cell Carcinoma Diagnosis and Follow-Up: Current Status and Perspectives

“…As described in Table 1, many studies have applied salivary ctDNA in the management of head and neck squamous cell carcinoma (HNSCC) (Liao et al, 2000;El-Naggar et al, 2001;Viet and Schmidt, 2008;Sethi et al, 2009;Demokan et al, 2010;Carvalho et al, 2011;Guerrero-Preston et al, 2011;Sun et al, 2012;Rettori et al, 2013;Ramadoss et al, 2015;Wang et al, 2015;Ferlazzo et al, 2017;Lacombe et al, 2017). When HNSCC patients with tumors at the oral cavity, oropharynx, larynx, and hypopharynx were enrolled at the early stages (I and II) and late stages (III and IV), ctDNA was detected, respectively, in 100% of HNSCC patients enrolled at the early stages and in 95% enrolled at the late stages, with an enrichment in saliva of all patients affected by OSCC; this result is very specific for OSCC detection.…”

“…Epigenetic alterations such as DNA methylation rate can be easily detected in salivary ctDNA, proving to be a valuable sensitive and specific marker for OSCC diagnosis and prognosis (Demokan et al, 2010;Pattani et al, 2010;Guerrero-Preston et al, 2011;Ferlazzo et al, 2017). Moreover, the evaluation of the methylation status of genes, involved in OSCC development at diagnosis, seems to be useful as a predictive factor to develop a personalized therapy and assess the patient response during surveillance (Viet and Schmidt, 2008;Lacombe et al, 2017).…”

Overcoming challenges in human saliva gene expression measurements

“…Besides DNA, proteins and various metabolites, RNA has also been shown as a promising marker in other tissues and body fluids, providing complex gene expression information. Because saliva is derived from several tissue sources and that it also contains large amounts of total RNA make it one of the most attractive diagnostic, prognostic, and monitoring tools for both systemic and oral diseases [2][3][4] . Hereby, saliva has been shown to contain RNA biomarkers (mRNA and small RNA species) for prediction and diagnosis of several diseases 5 , especially of the oral cavity such as oral cancer 6,7 or disorders of the salivary glands 8,9 .…”