Nuclear and mitochondrial DNA s microsatellite instability and mitochondrial DNA copy number in adenocarcinoma and squamous cell carcinoma of lung: a pilot study

Mitochondrial genetic changes are considered as a key molecular step of mutations in various cancers. To clarify the role of genetic instability in lung cancer, we analyzed clinicopathological characteristics and frequencies of nuclear and mitochondrial microsatellite instability ( nMSI and mt MSI ), and alteration of mitochondrial DNA copy number (mt CN ) in adenocarcinoma ( ADC ) and squamous cell carcinoma ( SCC ) of lung. DNA was isolated from 48 patients with ADC and 42 with SCC . Markers for nMSI , BAT 25 and 26, and markers for mt MSI , (C)n and ( CA )n in mitochondrial D‐loop region, were utilized. The mt CN were measured by real‐time polymerase chain reaction. The nMSI was found in two patients (4.2%) of ADC and 6 (14.3%) of SCC . The mt MSI was detected in 10 patients (20.8%) of ADC and 8 (19.0%) of SCC . Mean mt CN was 5.05 ± 8.17 and 3.34 ± 5.14 in ADC and SCC respectively. The mt CN was increased in 35 patients (72.9%) of ADC and 30 (71.4%) of SCC . The mt MSI more frequently appeared in more advanced pathologic T stage in ADC (p = 0.003). Alterations of mt CN and a high frequency of mt MSI in our patient samples indicate that mitochondrial DNA is a potential molecular marker in lung cancers ( ADC and SCC ) correlating with their histological classification.