[Experimental research of neutrophil gelatinase-associated lipocalin siRNA encapsulated by urocanic acid-coupled chitosan on colon cancer cells].

Objective To explore the impact of neutrophil gelatinase-associated lipocalin (NGAL) knockdown by NGAL siRNA encapsulated with urocanic acid-modified chitosan nanoparticles (UAC) on the proliferation, migration and apoptosis of human colon cancer cells. Methods NGAL siRNA was encapsulated by UAC and chitosan (CTS) respectively, and then was transfected into human colon cancer cell lines HT29. The NGAL mRNA was detected by real-time quantitative PCR (RT-QPCR) . Relationships of NGAL gene silencing with the proliferation, migration and apoptosis of HT29 cell were analyzed. Results Under the fluorescence microscope, the transfection efficiency of siRNA in UAC group was (37.52 ± 7.17) %, which was significantly higher than (11.32 ± 3.39) % in CTS group (t= 6.102, P= 0.005) . Forty-eight hours after transfection, RT-QPCR examination showed that the level of NGAL mRNA expression was 0.350 in UAC group and 0.529 in CTS group with significant difference (t=-3.743, P= 0.02) , meanwhile both levels were significantly lower as compared to control group (F= 163.538, P < 0.001) . Proliferation analysis revealed that after silencing NGAL gene, proliferation rate of UAC group and CTS group was slightly lower than control group, and no significant differences were found (F= 9.520, P= 0.438) . However, migration assay demonstrated that the 24-hour migration rate of UAC group and CTS group was significantly lower than that of control group (F= 6.756, P= 0.029) , meanwhile the migration rate of UAC group was slightly lower than that of CTS group[ (77.90 ± 7.14) % vs. (87.67 ± 3.98) %, t=-1.704, P= 0.164]. Apoptosis detection revealed that the apoptosis rate in UAC group was significantly higher than that in CTS group and the control group 2 days after transfection[ (15.800 ± 1.054) % vs. (12.900 ± 0.656) %, (11.933 ± 1.914) %, F=7.004, P= 0.027]. Conclusions The encapsulated ability and transfection efficiency of chitosan modified by urocanic acid elevate significantly. Silencing NGAL gene by UAC carrier can down-regulate the expression of NGAL mRNA in HT29 colon cell line, inhibit their migration and facilitate their apoptosis. Key words: Colorectal neoplasms; Neutrophil gelatinase-associated lipocalin; Chitosan; RNA interference