Abstract: Objective To observe NLS-KALA-SA-PTX (NKSP) for lung adenocarcinoma cell line A549 in vitro with paclitaxel monotherapy, and the mechanism thereof. Methods MTT assay was used to detect A549 cell proliferation influenced by different concentrations of NKSP (20, 40, 80, 100 μg/L) and paclitaxel monotherapy (20, 40, 80, 100 μg/L) for 24 h, 48 h and 72 h.. Subsequent experiments were divided into four groups, namely, group A (without any drug treatment), group B (added polypeptide 80 μg/L of self-assembled nanoparticles, NKS), group C (80 μg/L paclitaxel monotherapy) and group D (80 μg/L NKSP). Flow cytometry was used to detect the cell apoptotic rates after 48 h and 72 h treatment in four groups. Western blot assay was used to analyse the protein expressions of bax and caspase-3 after 48 h and 72 h treatment in four groups. Results Both paclitaxel monotherapy and NKSP can inhibit the proliferation of A549 cells. The inhibitory rates of paclitaxel monotherapy group at 48 h and 72 h and NKSP group at 72 h showed an increasing trend in a dose-dependent manner (P < 0.05). After treatment for 48 hours, the apoptotic rate was significantly higher in D group than that of C group (P < 0.05). But the apoptotic rate at 72 h was lower in D group than that of C group (P < 0.05). The protein expressions of bax and caspase-3 at 48 h were significantl lower in D group than those of C group, which were higher at 72 h in D group than those of C group (P < 0.05). Conclusion Compared to paclitaxel monotherapy group, NKS promotes slow release of paclitaxol, which reduces the cytotoxicity and extends the antitumor effects.

Key words: lung neoplasms, adenomatosis, pulmonary, nanospheres, antineoplastic agents, in vitro, paclitaxel, A549 cells