Study for the Development of Therapy Based on the Regulation of the myc Gene Expression in Lung Cancer

小细胞肺癌(SCLC)中c-myc基因表达和视黄醇信号转导通路异常常见，常伴有肿瘤复发，是导致SCLC患者预后不良的原因之一。在这项研究中，我们研究了c-myc反义寡核苷酸硫代磷酸(OPT)与全反式维甲酸(RA)联合使用是否能更有效地抑制高表达c-myc并扩增c-myc基因的小细胞肺癌细胞株NCI-H82的生长，以及这种联合应用是否可以作为抗小细胞肺癌的实验性治疗工具。在Northern和Western印迹分析中，c-myc反义OPT降低了c-myc的表达，从而使细胞生长抑制率达到40%，细胞凋亡率比对照和正义OPT高10%(分别为P&lt；0.01和P&lt；0.05)。全反式维甲酸还通过下调c-myc的表达抑制细胞增殖，抑制率达40%。在获得这些结果后，我们检验了这样的假设，即c-myc反义OPT与全反式RA联合使用可能进一步降低c-myc的表达，并导致改善细胞生长控制。联合用药比单独使用任何一种药物(P&lt；0.01)都显示出抑制细胞增殖的作用(与对照组或正义OPT单独使用相比，细胞生长抑制了60%，P&lt；0.01)，这是通过增强c-myc表达的下调而实现的。总之，c-myc反义DNA联合其他方法下调c-myc可能是未来基于基因调控的小细胞肺癌治疗的一种有吸引力的方法，尽管需要进一步使用新的寡核苷酸类似物、针对DNA进入细胞的特定干预措施以及更有效的治疗药物来加强c-myc下调和细胞生长抑制。

The disregulation of both c-myc expression and retinoid signaling pathways commonly occurs in small cell lung cancers (SCLCs), frequently accompanying tumor relapse, and contributing to the poor prognosis of patients with SCLCs. In this study, we investated whether c-myc antisense oligodeoxynucleoside phosphorothioate (OPT) covering the translational site of c-myc mRNA used in combination with all-trans-retinoic acid (RA) would be more effective than either agent alone in inhibiting the growth of an SCLS cell line, NCI-H82, overexpressing c-myc with amplification of the gene, and whether this combination could be an experimental therapeutic tool against SCLCs. C-myc Antisense OPT decreased c-myc expression in Northern and Western blot analyses, thus including 40% cell growth inhibition and 10% higher frequency of apoptosis compared with control scrambled and sense OPTs (P<0.01, and P<0.05, respectively). All-trans RA also inhibited cell proliferation at the rate of 40% by down-regulating c-myc expression. Having obtained these results, we tested the hypothesis that c-myc antisense OPT in combination with all-trans-RA may further reduce c-myc expression and lead to improved cell growth control. This combination showed an inhibition of cell proliferation than either agent given alone (P<0.01) (60% inhibition of cell growth compared with treatment of control scrambled or sense OPT alone, p<0.01) through enhanced down-regulation of c-myc expression. In conclusion, c-myc antisense DNA in combination with other modalities for c-myc down-regulation may represent an attractive gene regulation-based therapy of SCLCs in the future, although further efforts using new oligodeoxynucleotide analogues, specific interventions for DNA delivery into cells, and more potent therapeutic agents are required to increase the potentiation of c-myc down-regulation and cell growth inhibition.