Objective        To compare the mitochondrial DNA (mtDNA) mutations between small cell lung cancer (SCLC) cell lines and their corresponding multidrug-resistant cell lines

and to investigate whether the mtDNA mutations were involved in the development and multidrug-resistant phenotype of SCLC.       Methods      The SCLC cell lines of H446

H69 and H1395

and the multidrug-resistant SCLC cell lines of H69AR

H446/CDDP and H1395/CDDP were cultured. After the genomic DNA was extracted from the 6 cell lines

respectively

the mtDNA genome was amplified and sequenced using 26 primer pairs. mtDNA mutations were determined using DNASTAR Lasergene v7.1 software to compare the sequencing data with the revised Cambridge Reference Sequence (rCRS) of mtDNA.       Results       H446 and H446/CDDP belonged to mtDNA haplogroup G

H1395 and H1395/CDDP belonged to mtDNA haplogroup C

and H69 and H69/AR belonged to mtDNA haplogroup N. Additionally

several mtDNA mutations detected among the SCLC cells mentioned above might not only affect the second structure of rRNA and tRNA

but also cause the changes of amino acid types and their biological properties. The changes might affect mitochondrial oxidation and cell apoptosis. However

no specific mtDNA mutations were detected between the cells of progenitor cell lines and multidrug-resistant cell lines in the present study.       Conclusion       Multidrug-resistant phenotype of SCLC may not be associated with mtDNA mutation

but the occurrence and development of SCLC might be closely related to mtDNA mutation. The study provides an experimental and theoretical basis for further investigation of the mechanism of SCLC occurrence and development.