The microtubule depolymerizing agent naphthazarin induces both apoptosis and autophagy in A549 lung cancer cells

Abstract

Naphthazarin (DHNQ, 5,8-dihydroxy-l,4-naphthoquinone) is a naturally available 1,4-naphthoquinone derivatives. In this study, we focused on elucidating the cytotoxic mechanism of naphthazarin in A549 non-small cell lung carcinoma cells. Naphthazarin reduced the A549 cell viability considerably with an IC(50) of 16.4 ± 1.6 μM. Naphthazarin induced cell death in a dose- and time-dependent manner by activating apoptosis and autophagy pathways. Specifically, we found naphthazarin inhibited the PI3K/Akt cell survival signalling pathway, measured by p53 and caspase-3 activation, and PARP cleavage. It also resulted in an increase in the ratio of Bax/Bcl2 protein levels, indicating activation of the mitochondrial apoptotic pathway. Similarly naphthazarin triggered LC3II expression and induced autophagic flux in A549 cells. We demonstrated further that naphthazarin is a microtubule inhibitor in cell-free system and in A549 cells. Naphthazarin treatment depolymerized interphase microtubules and disorganised spindle microtubules and the majority of cells arrested at the G(2)/M transition. Together, these data suggest that naphthazarin, a microtubule depolymerizer which activates dual cell death machineries, could be a potential novel chemotherapeutic agent.

Naphthazarin suppresses cell proliferation and induces apoptosis in human colorectal cancer cells via the B-cell lymphoma 2/B-cell associated X protein signaling pathway

“…The results of the present study revealed that naphthazarin promoted Bax expression and inhibited Bcl-2 protein expression, and increased caspase-3 activation in SW480 cells. These results are in accordance with those of Acharya et al (9) who reported that naphthazarin increases the Bax/Bcl-2 protein ratio in A549 lung cancer cells.…”

“…Naphthazarin is an important active ingredient, which exhibits extensive pharmacological activities, including antitumor activity, and due to its low toxicity, it has gained considerable attention (9,10). However, to date the anticancer effects of naphthazarin on human colorectal cancer cells have not been reported.…”

Autophagy and microtubules – new story, old players

“…Indeed, at least part of the cytotoxic effect of the MT-stabilizer Taxol is dependent on its ability to block autophagosome maturation (Veldhoen et al, 2012). Conversely, other tubulin-binding drugs, such as vinblastine, naphtharazin or 2-methoxyestradiol, might instead stimulate autophagy, which could contribute to their anticancer activity (Acharya et al, 2011;Chen et al, 2008;Kamath et al, 2006;Köchl et al, 2006;Lorin et al, 2009). In the context of neurodegenerative diseases, the link between MT-acting drugs and autophagy could also prove to be important.…”

A synthetic curcumin derivative hydrazinobenzoylcurcumin induces autophagy in A549 lung cancer cells

“…Autophagy is the process of sequestering cytoplasmic proteins into the lytic component and is characterized by the formation and promotion of acidic vesicular organelles (AVOs) (Acharya et al, 2011;Wang et al, 2012). To detect the development of AVOs, A549 cells were treated with various concentrations of HBC for different lengths of time, and then cells were stained with acridine orange (5 mg/mL) for 40 s at room temperature.…”

“…During authophagy, autophagosomes fuse with lysosomes to form autophagolysosomes (Acharya et al, 2011;Wang et al, 2012). Autophagolysosomes could be dyed by acridine-orange which produced the red fluorescence.…”