Involvement of Circulating Cell-Free Mitochondrial DNA and Proinflammatory Cytokines in Pathogenesis of Chronic Obstructive Pulmonary Disease and Lung Cancer

Olga Bulgakova, A. Zh. Kausbekova, Assiya Kussainova, Nurtas Kalibekov, Dulat Serikbaiuly, Rakhmetkazhi I. Bersimbaev

Asian Pacific Journal of Cancer Prevention, 2021

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DOI 10.31557/apjcp.2021.22.6.1927
Data confidence 85 high
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Abstract

OBJECTIVE: Circulating cell-free mitochondrial DNA (cf-MtDNA) has been reported in patients with chronic obstructive pulmonary disease (COPD) and lung cancers. However, inter-relationships among the three biological events have not been well-characterized. Therefore, our investigation was conducted to better understand the role of cf-MtDNA on pathogenesis of the two diseases. METHODS: Plasma samples were collected from 64 non-small cell lung cancer (NSCLC) patients (before therapy), 45 patients with COPD and 62 healthy individuals. cf-MtDNA copy numbers were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and cytokines were determined using a human ELISA kit. RESULTS: Our data indicate that smoking statuses of the patients and controls were significantly associated with increased cf-MtDNA in plasma samples. Furthermore, NSCLC patients had significantly higher cf-MtDNA copy numbers than COPD patients (p < 0.03) and normal controls (p < 0.02), together with elevated proinflammatory cytokines over the controls (p < 0.05). Our study shows that the copy numbers for the NSCLC patients were positively associated with their subsequent metastasis but inversely associated with their overall survival. Conclusion: Our study indicates certain lung injury (e.g., from cigarette smoking) was responsible for the release of cf-MtDNA and proinflammatory cytokines into plasmas among our patients and controls. The increase in cf-MtDNA copy numbers was significantly associated with the development of both COPD and NSCLC, with increase in interleukin 6, and from our 5-year follow-up, with poor prognosis among the NSCLC patients. Therefore, with further validation, cf-MtDNA can be considered for use as diagnostic and prognostic biomarkers for NSCLC.