Mutations in the mitochondrial genome confer resistance of cancer cells to anticancer drugs

已经确定大多数癌细胞在线粒体基因组（mtDNA）中具有同质体细胞突变。我们表明mtDNA中的体细胞突变与抗癌药物耐受性有关。我们使用跨线粒体杂交细胞（cybrids）通过排除核背景的影响，揭示mtDNA突变在胰腺癌中的作用。来源于具有mtDNA突变的去核胰腺癌细胞（CFPAC-1，CAPAN-2）。我们构建了几个具有来自癌细胞的突变的胞质杂交体以及具有来自健康个体的野生mtDNA的胞质杂交体。比较了突变体和野生体对星孢菌素（STS）、5-FU、顺铂（CDDP）的体外耐药性，发现突变体对STS、5-FU、CDDP的耐药性均高于野生体，但对高温的耐药性除外。接下来，检查Sub-G1群体以估计细胞凋亡期间的核DNA片段化。STS处理增加Sub-G1种群更大的野生型胞质杂种比突变型胞质杂种。值得注意的是，细胞色素c氧化酶的抑制剂阻止了STS野生型胞质杂种的Sub-G1群体的增加，表明呼吸链活性参与STS诱导的细胞凋亡。此外，我们还研究了cyt。c从免疫染色中释放。野生型胞质杂交体的细胞大多数丢失m，抗cyt染色。c抗体，表示cyt。c释放到胞质溶胶中。相反，突变体胞质杂交体保持线粒体膜电位和共定位的细胞色素。C.这些结果表明，胰腺癌的mtDNA突变抑制了细胞周期。我们的结果表明mtDNA突变可以赋予癌细胞化疗耐药性.

It has been established that the majority of cancer cells harbor homoplasmic somatic mutations in the mitochondrial genome(mtDNA).We show that somatic mutations in mtDNA are involved in anticancer drug-tolerance.We used trans-mitochondrial hybrid cells (cybrids) to reveal the role of mutations in mtDNA in the pancreatic cancer by excluding any effects of the nuclear background.Cybrids were constructed by repopulating HeLa devoid of mtDNA with mtDNA derived from enucleated the pancreatic cancer cells(CFPAC-1,CAPAN-2)harboring mtDNA mutations. We constructed several cybrids with mutations derived from the cancer cells as well as those with wild mtDNA derived healthy individuals. We compared the mutant and wild cybrids in resistance against staurosporine(STS), 5FU, CDDP in vitro.The experiment revealed mutant cybrids were more resistant against the drugs than wild cybrids except hyperthermia. Next, Sub-G1 populations were examined to estimate nuclear DNA fragmentation during apoptosis. STS treatment increased Sub-G1 populations more greatly in wild cybrids than in mutant cybrids. Notably, an inhibitor of cytchrome c oxidase prevented the increase in Sub-G1 population of wild cybrids with STS, suggesting respiratory chain activity is involved in STS-induced apoptosis. Furthermore, we investigated cyt. c release from mitochondriaby immunostaining. Most cells of wild cybrid lost m and were stained with anti-cyt. c antibody,indicating cyt. c release to the cytosol. In contrast, mutant cybrids maintained mitochondrial membrane potential and co-localization of cyt. c. These results indicate that mtDNA mutations of the pancreatic cancer inhibit cyt. c -dependent apoptosis.Our results demonstrate that mtDNA mutationscan confer chemoresistance on cancer cells.