In this abstract, we present preliminary data from a research project related to epigenetic modifications as the use of omics in cancer symptom assessment, diagnosis, and potentially intervention. Fatigue, one of the most frequently reported symptoms in patients with cancer, can profoundly affect a cancer patient’s quality of life, treatment adherence, and health care utilization. 1-3 Currently, there is no Food and Drug Administration (FDA)-approved pharmacological agent that effectively prevents or treats fatigue.8 Understanding the molecular mechanisms of fatigue is critical to its successful management and development of targeted therapies. Recent studies have linked cancer-related fatigue with inflammation even long after the completion of cancer treatment.9-11 However, the mechanisms for the persistence of inflammation and fatigue long after treatment completion have yet to be understood. Epigenetics refers to the regulation of gene activities that does not involve alteration of DNA sequence.12 Environmental stimuli, such as diet, pollution, infections, or cancer treatment, have profound effects on epigenetic modifications that can, thereafter, trigger susceptibility to disease or synmptoms.13,14 Therefore, one potential explanation could be that cancer and its treatment leads to acute, but long-lasting epigenetic changes that may predispose to persistent inflammation and fatigue. DNA methylation is the well-studied epigenetic modification, and has been characterized in various disease processes including cancer, psychiatric symptoms, and inflammation.12,15-17 This study sought to explore DNA methylation changes associated with inflammation and fatigue in patients undergoing chemoradiotherapy for head and neck cancer (HNC). The reported methods and preliminary data were from our ongoing study. This presentation may also provide how we, as nurse scientists, design our studies to link the epigenetic changes to biological pathways that may help us to understand the mechanisms and potential intervention targets for patient-reported symptoms.
Methods:
Data were collected at pre- and one-month post radiotherapy. Patients were enrolled at the Radiation Oncology Clinics of Emory Healthcare. The main inclusion criteria were: histological proof of squamous cell carcinoma of the head and neck region; any clinical stage with no distant metastasis; and no major organ disease. Main exclusion criteria were: evidence of metastases; simultaneous primaries; previous invasive malignancies; and patients with major psychiatric disorders or those who cannot understand English.
Demographic and clinical variables were collected at baseline and/or follow up as appropriate through administration of standardized patient reported questionnaires. Fatigue was measured by using the Multidimensional Fatigue Inventory (MFI)-20, with a well-established validity and reliability (α=0.84) in use with patients with cancer.18,19 Blood samples were collected at the same day as the questionnaires using EDTA tubes. DNA was isolated from peripheral blood monocyte cells (PBMCs) according to the manufacturer’s protocol. The HumanMethylation450K BeadChip (Illumina; San Diego, CA) was used to test >480,000, methylation sites quantitatively across the genome.
Results:
Pilot data was generated from 12 HNC patients, 6 of whom had a significant increase in fatigue (defined as an increase of more than 25 points out of 100 from pre-to one-month post-chemoIMRT) and another 6 that had less than a 15 point increase over time). These data showed a promising link between fatigue status and DNA methylation changes. We evaluated DNA methylation changes across the genome before and after chemoIMRT. DNA methylation of CpG sites in 643 genes changed more than 10%. Genes whose methylation levels changed in response to chemoIMRT were enriched for 338 specific Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways (6.73x10-22<pcorr<.05) including immune response and cancer pathways. We next evaluated whether methylation of CpG sites that changed before and after chemoIMRT associated with differences in fatigue. Recognizing that a study of 12 subjects is unlikely to have the power necessary to achieve significance after multiple test correction, we concentrated on the 1199 CpG sites that changed in response to chemoIMRT. Overall, 306 chemoIMRT-responsive CpG sites (25.5%) associated with fatigue (p<.05), which is more than 5x what would be expected by chance (p<.0001). Among the top 5 CpG sites that most associated with fatigue, RNASET2, the gene containing the most associated CpG site (cg11301670), has been implicated in chromosomal rearrangements and tumor malignancy CITE.20-22 In addition, CpG sites in the interleukin (IL)-6 receptor (cg21262032) and a Tumor Necrosis Factor (TNF) Ligand (cg12045829), both of which are inflammatory markers, were also among the top five that most associated with fatigue.
Conclusion:
The preliminary data from the pilot study suggested that epigenetic regulation of immune mediators may contribute to inflammation and persistent fatigue in these patients. Larger data are needed to verify the findings. As nurse scientists, we may be able to identify epigenetic modifications and to use them as predictive and prognostic biomarkers for symptoms and as interventional targets for the management of these symptoms.