Conclusion
Our preclinical studies demonstrated that RNAi therapy
against PLK-1 using atelocollagen is effective against liver
metastatic NSCLC cancers. Recently, several clinical trials
for cancer therapy are ongoing (Additional file 1: Table
S1, http://clinicaltrials.gov/ct2/home). Although RNAi
shows excellent specificity in gene-silencing, several
adverse effects including activation of immune reaction
[66,67] and off-target effects (induction of unintended
gene silencing) [68] are brought in in vivo application.
Safer and more efficient DDSs for systemic delivery are
warranted to be developed. Moreover, studies to establish
the pharmacokinetics and pharmacodynamics of siRNAs
on the administration are necessary steps in the potential
approval of siRNA as a tool for cancer therapy. To maximize
efficacy and to minimize adverse effects of RNAi, it
should be determined whether siRNAs are best administered
alone or in combination with chemotherapeutic
agents [69,70], and whether it is better to administer asingle specific siRNA or multiple specific siRNAs
[57,71-73]. In conclusion, RNAi therapy represents a
powerful strategy against advanced lung cancers and may
offer a novel and attractive therapeutic option. The success
of RNAi depends on the suitable selection of target
genes and the development of DDSs. We anticipate that
the continued development of effective DDSs and the
accumulation of evidence further proving the success of
siRNA treatment will advance RNAi as a promising strategy
for lung cancer therapy.