Short hairpin RNA targeting AKT1 and PI3K/p85 suppresses the proliferation and self-renewal of lung cancer stem cells.

The aim of the present study was to investigate the effect of short hairpin (sh)RNA targeting AKT1 and phosphatidylinositol 3-kinase (PI3K)/p85 on the proliferation and self-renewal of lung cancer stem cells (LCSCs). The recombinant adenovirus expression vector, which contained shRNA targeting open reading frames of AKT1 and PI3K/p85, was transfected into LCSCs. It was found that AKT1 and PI3K/p85 expression was upregulated in LCSCs compared with that in the primary lung cancer cells. Recombinant adenovirus vector rAd5-siAKT1-siPI3K/p85 significantly downregulated AKT1 and PI3K/p85 mRNA and protein expression in LCSCs. The downstream factors, proliferating cell nuclear antigen (PCNA) and cyclin D1 were also downregulated, while p53 was upregulated. Following silencing of AKT1 and PI3K/p85, cell proliferation, tumor sphere formation and tumor formation in NOD/SCID mice were also reduced. According to the present results, it was hypothesized that the PI3K/Akt signaling pathway is important in the self­renewal and proliferation of LCSCs, and that targeting the PI3K/Akt signaling pathway decreases the rate of tumor formation in vivo.

Isolation, cultivation and identification of human lung adenocarcinoma stem cells.

Recently, an increasing number of studies have demonstrated that lung cancer is a stem cell disease. However, ideal cell surface markers for isolating stem cells in lung cancer are yet to be identified. In the present study, a cell population with a cluster of differentiation (CD)133+ phenotype was successfully isolated from a single cell suspension of lung adenocarcinoma tissue using magnetic-activated cell sorting (MACS) and enriched in a serum-free culture. In comparison to CD133- cells, the CD133+ cells exhibited an enhanced capacity for self-renewal and differentiation, and a greater potential for in vivo tumor formation, in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. Tumors could be induced in NOD/SCID mice by the transplantation of 102 stem-like cells per mouse. The results of the present study demonstrated that CD133 may serve as a specific cell surface marker for lung adenocarcinoma stem cells, and that MACS combined with serum-free culture is an effective method for isolating and enriching lung cancer stem cells.

In vivo evaluation of curcumin-loaded nanoparticles in a A549 xenograft mice model.

Curcumin (Cum) has been reported to have potential chemo-preventive and chemotherapeutic activity through influencing various processes, inducing cell cycle arrest, differentiation and apoptosis in a series of cancers. However, the poor solubility of Cum limits its further applications in the treatment of cancer. We have previously reported Cum-loaded nanoparticles (Cum-NPs) prepared with amphilic methoxy poly(ethylene glycol)-polycaprolactone (mPEG-PCL) block copolymers. The current study demonstrated superior antitumor efficacy of Cum-NPs over free Cum in the treatment of lung cancer. In vivo evaluation further demonstrated superior anticancer effects of Cum-NPs by delaying tumor growth compared to free Cum in an established A549 transplanted mice model. Moreover, Cum-NPs showed little toxicity to normal tissues including bone marrow, liver and kidney at a therapeutic dose. These results suggest that Cum-NPs are effective to inhibit the growth of human lung cancer with little toxicity to normal tissues, and could provide a clinically useful therapeutic regimen. They thus merit more research to evaluate the feasibility of clinical application.