Upregulation of α-synuclein during localized radiation therapy signals the association of cancer-related fatigue with the activation of inflammatory and neuroprotective pathways.

PURPOSE: Neuroinflammatory mechanisms are associated with fatigue in neurodegenerative conditions such as Parkinson's. The symptoms in Parkinson's including fatigue are thought to be related to α-synuclein overexpression. This study investigated genomic correlates of fatigue experienced by men with prostate cancer receiving external beam radiation therapy (EBRT). PATIENTS AND METHODS: Sixteen men with non-metastatic prostate cancer who were scheduled to receive EBRT were enrolled. Fatigue scores and blood were obtained at baseline (prior to EBRT, D0); one hour following initiation of EBRT (D1), day 7 (D7), day 14 (D14), midpoint (days 19-21, D21), completion (days 38-42, D42), and four weeks post-EBRT (days 68-72, D72). Gene expression profiling using microarray analysis was performed from peripheral blood and confirmatory qPCR and protein (ELISA) analyses verified the microarray results. Correlations between fatigue and gene/protein expressions were determined using a mixed model approach. RESULTS: Microarray data showed significant, differential expression of 463 probesets following EBRT. SNCA had a 2.95-fold change at D21 from baseline. SNCA expression was confirmed by qPCR (p<0.001) and ELISA (p<0.001) over time during EBRT. Fatigue scores were significantly correlated with SNCA gene expression on D14 (r=0.55, p<0.05) and plasma α-synuclein concentrations on D42 of EBRT (r=0.54, p=0.04). CONCLUSION: Fatigue experienced during EBRT may be mediated by α-synuclein overexpression. Alpha-synuclein may serve as a useful biomarker to understand the mechanisms and pathways related to the development of fatigue in this population.

A systematic review of the association between immunogenomic markers and cancer-related fatigue.

Fatigue, which is one of the most commonly reported symptoms in cancer, can negatively impact the functional status and the health-related quality of life of individuals. This paper systematically reviews 34 studies to determine patterns of associations between immunogenomic markers and levels of cancer-related fatigue (CRF). Findings from the longitudinal studies revealed that elevated fatigue symptoms especially of women with early stages of breast cancer were associated with high levels of neutrophil/monocyte, IL-1ra, and IL-6 during radiation therapy; high levels of CD4+, IL-1ß, and IL-6 with stressing stimuli; high levels of IL-1ß during chemotherapy; low NK cell levels after chemotherapy; and presence of homozygous IL-6 and TNF alleles. In the cross-sectional studies, associations between levels of fatigue and immune/inflammatory markers were not consistently found, especially when covariates such as BMI, ethnicity, menopausal status, and educational level were controlled in the statistical analyses. However, a number of genomic markers were observed to be elevated mostly in fatigued breast cancer survivors in the cross-sectional studies. Gaps in knowledge and recommendations for future research are discussed.

Lower brain-derived neurotrophic factor levels associated with worsening fatigue in prostate cancer patients during repeated stress from radiation therapy.

OBJECTIVES: Fatigue during cancer treatment is associated with depression. Neurotrophic factors play a major role in depression and stress and might provide insight into mechanisms of fatigue. This study investigated the association between plasma concentrations of three neurotrophic factors (BDNF, brain-derived neurotrophic factor; GDNF, glial-derived neurotrophic factor; and SNAPIN, soluble N-ethylmaleimide sensitive fusion attachment receptor-associated protein) and initial fatigue intensification during external beam radiation therapy (EBRT) in euthymic non-metastatic prostate cancer men. METHODS: Fatigue, as measured by the 13-item Functional Assessment of Cancer Therapy-Fatigue (FACT-F), and plasma neurotrophic factors were collected at baseline (prior to EBRT) and mid-EBRT. Subjects were categorized into fatigue and no fatigue groups using a > 3-point change in FACT-F scores between the two time points. Multiple linear regressions analysed the associations between fatigue and neurotrophic factors. RESULTS: FACT-F scores of 47 subjects decreased from baseline (43.95 ± 1.3) to mid-EBRT (38.36 ± 1.5, P < 0.001), indicating worsening fatigue. SNAPIN levels were associated with fatigue scores (rs = 0.43, P = 0.005) at baseline. A significant decrease of BDNF concentration (P = 0.008) was found in fatigued subjects during EBRT (n = 39). CONCLUSIONS: Baseline SNAPIN and decreasing BDNF levels may influence worsening fatigue during EBRT. Further investigations are warranted to confirm their role in the pathophysiology and therapeutics of fatigue.