Cancer stem cells (CSCs) represent a small subpopulation within a tumour. These cells possess stem cell-like properties but also initiate resistance to cytotoxic agents, which contributes to cancer relapse. Natural compounds such as curcumin that contain high amounts of polyphenols can have a chemosensitivity effect that sensitises CSCs to cytotoxic agents such as cisplatin. This study was designed to investigate the efficacy of curcumin as a chemo-sensitiser in CSCs subpopulation of non-small cell lung cancer (NSCLC) using the lung cancer adenocarcinoma human alveolar basal epithelial cells A549 and H2170. The ability of curcumin to sensitise lung CSCs to cisplatin was determined by evaluating stemness characteristics, including proliferation activity, colony formation, and spheroid formation of cells treated with curcumin alone, cisplatin alone, or the combination of both at 24, 48, and 72 h. The mRNA level of genes involved in stemness was analysed using quantitative real-time polymerase chain reaction. Liquid chromatography-mass spectrometry was used to evaluate the effect of curcumin on the CSC niche. A combined treatment of A549 subpopulations with curcumin reduced cellular proliferation activity at all time points. Curcumin significantly (p < 0.001) suppressed colonies formation by 50% and shrank the spheroids in CSC subpopulations, indicating inhibition of their self-renewal capability. This effect also was manifested by the down-regulation of SOX2, NANOG, and KLF4. Curcumin also regulated the niche of CSCs by inhibiting chemoresistance proteins, aldehyde dehydrogenase, metastasis, angiogenesis, and proliferation of cancer-related proteins. These results show the potential of using curcumin as a therapeutic approach for targeting CSC subpopulations in non-small cell lung cancer.
The active isolate of LF1 in Leptospermum javanicum was further looked into its capabilities in provoking an apoptotic reaction and suppressing the metastasis process in treated non-small lung cancer cells. LF1 underwent isolation and purification to yield a white powder which was identified as Betulinic acid (BA) via NMR, LCMS and IR spectroscopy. The isolate, BA, which produced an encouraging cytotoxic effect against non-small lung cancer cells (A549 and NCI-H1299) through the MTT assay, was further assessed with TUNEL, Sub-G1 population quantification, acridine orange/ethidium bromide staining as well as activated caspase-3 detection. The results pointed towards the induction of apoptosis as a result of increasing doses of BA, regardless of the p53 status in both cell lines. Treatment with BA also prevented an effective attachment of the invasive A549 cells onto a new culture surface in addition to diminishing the migratory potential of treated cells across a porous membrane. Further investigation through the ELISA detection and gelatin zymography showed an adverse effect to production of matrix metalloproteinase-2 (MMP-2) while the levels of matrix metalloproteinase-9 (MMP-9) were not negatively affected. The findings from this study validate the potential of L. javanicum as a potential anti-cancer treatment as stated in our previous study. The isolate, BA not only showed a capacity in inducing apoptotic cell death in non-small lung cancer cells, but managed to distort the ability of the cancer cells in effectively undergoing the metastasis process.
This study aimed to determine whether the clinicopathological features of lung cancer in patients younger than 40 years differ from that of older patients in an Asian country.