Influence Of Midkine On Proliferation And Apotosis Of Lung Adenocarcinoma Cell Lines A₅₄₉

Objective: 1. To clarify the influence of Midkine (MDK) on proliferation and apoptosis of lung adenocarcinoma cell lines A549; 2 . To study new biological diagnosis criteria and therapeutic methods for lung adenocarcinoma.Methods: RNA interference technique was applied to silent the MDK gene on lung adenocarcinoma A549 lines. According to the different MDK siRNA sequences transfected, lung adenocarcinoma cell lines A549 were divided into three groups (group MDKsiRNA-1, MDK siRNA -2 and MDKsiRNA-3). In addition, cells were transfected with non-treated were processed and no-load liposome and negative siRNA sequences, positive siRNA sequences as control groups (Control A, control B,control C and control D respectively).Liposome transfection method was used to transfect MDK siRNA , Cell proliferation rate was tested by the MTT, Western blot test was performed to detect the Caspase-3 protein , member of Caspase family , expression on all groups of cells, additionally, the activity of Caspase - 3 was examined with Caspase -3 Activity Assay kit.Results: MTT results showed the proliferation rate were: MDKsiRNA-1(17.8±12.9)%,MDKsiRNA-2(12.9±4.6)%,MDKsiRNA-3(13.5±3.9)%, Control group A(23.8±2.7)%,and Control B(25.3±4.3) % .Both proliferation rates of MDKsiRNA-2 and MDKsiRNA-3 were remark- ably lower than those in Control group (p < 0.05), while MDK siRNA - 1 had no considerable difference (p>0.05), there was no significant difference between the control groups (p>0.05). Compared with control groups, western blot results showed the expression amount of caspase-3 OD value were: Control-A (0.03±0.0040), MDKsiRNA-3(0.40±0.013), MDKsiRNA-2(0.51±0.013), MDKsiRNA-1(0.10±0.019), Control-D(0.13±0.007), Control-C(0.07±0.004) Compared with control groups, MDKsiRNA- 2 and -3 group were increased in various degree (p< 0.05), and those of MDK siRNA-1 were not raised majorly (p > 0.05). Caspase -3 Activity Assay kit results revealed the A405 OD value of all groups of cells: MKsiRNA-1 (0.19±0.004), MDKsiRNA-2(0.45±0.021), MDKsiRNA-3 (0.41±0.005), Control-A(0.14±0.003), Control-C(0.15±0.003), Compared with control groups, MDKsiRNA- 2 and -3 group were increased in various degree (p< 0.05), and those of MDK siRNA-1 were not raised majorly (p > 0.05).Conclusion: 1. MDKsiRNA in vitro can inhibit the proliferation of lung adenocarcinoma cells A549.2 .MDKsiRNA in vitro is able to promote the expression and activity of Caspase-3 on cells A549, and thus to induce its apoptosis.3 .Three MDKsiRNA designed have various impact on proliferation and apoptosis on cells A549, which provided experimental evidence for selecting highly specific MDKsiRNA.4. This study shows the potential of it to establish new biological diagnosis and target treatment for lung adenocarcinoma cancer.