Novel ANO1 Inhibitor from Mallotus apelta Extract Exerts Anticancer Activity through Downregulation of ANO1

Anoctamin1 (ANO1), a calcium-activated chloride channel, is frequently overexpressed in several cancers, including human prostate cancer and oral squamous cell carcinomas. ANO1 plays a critical role in tumor growth and maintenance of these cancers. In this study, we have isolated two new compounds (1 and 2) and four known compounds (3-6) from Mallotus apelta. These compounds were evaluated for their inhibitory effects on ANO1 channel activity and their cytotoxic effects on PC-3 prostate cancer cells. Interestingly, compounds 1 and 2 significantly reduced both ANO1 channel activity and cell viability. Electrophysiological study revealed that compound 2 (Ani-D2) is a potent and selective ANO1 inhibitor, with an IC₅₀ value of 2.64 μM. Ani-D2 had minimal effect on cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel activity and intracellular calcium signaling. Notably, Ani-D2 significantly reduced ANO1 protein expression levels and cell viability in an ANO1-dependent manner in PC-3 and oral squamous cell carcinoma CAL-27 cells. In addition, Ani-D2 strongly reduced cell migration and induced activation of caspase-3 and cleavage of PARP in PC-3 and CAL-27 cells. This study revealed that a novel ANO1 inhibitor, Ani-D2, has therapeutic potential for the treatment of several cancers that overexpress ANO1, such as prostate cancer and oral squamous cell carcinoma.

Xylan deposition and lignification in the multi-layered cell walls of phloem fibres in Mallotus japonicus (Euphorbiaceae)

Phloem fibres in Mallotus japonicus Müll. Arg. were found to have a multi-layered structure that is S1 + S2 + n(G + L), where a non-lignified gelatinous layer (G) and a lignified layer (L) are formed alternately and n indicates the number of repetitions of these two layers. The aim of this study was to determine the process of xylan deposition and lignification in the multi-layered cell walls of phloem fibres. The formation process of the multi-layered structure of secondary phloem fibres was examined by light microscopy, ultraviolet microscopy and transmission electron microscopy. The distribution of glucuronoxylan was examined by immunoelectron microscopy. The activity of peroxidase was also determined using metal-enhanced diaminobenzidine substrates. Immunolabelling of glucuronoxylan occurred in lignified cell wall layers, except in the compound middle lamella (CML), i.e., the S1, S2 and L layers but not the G layers. Change in immunolabelling density suggests that xylan deposition in these lignified layers occurs appositionally, i.e., xylan is deposited into the lignified layers directly and not by a penetrative mechanism, and deposition does not occur after the layers are fully deposited. Peroxidase activity was found in CML including cell corners during S2 layer formation, then in developing G layers during G layer formation. Peroxidase activity was also found in the thin L layers that formed recently and was not found in the L layers already present. Xylan labelling was not found in the thin L layers that formed recently but did occur in L layers that developed earlier. Lignification of the S1 and S2 layers continued during the formation of the G layers, whereas in the L layers it finished just after deposition of the L layer.

Effects of light on direct and indirect defences against herbivores of young plants of Mallotus japonicus demonstrate a trade-off between two indirect defence traits

BACKGROUND AND AIMS

Although most studies on plant defence strategies have focused on a particular defence trait, some plant species develop multiple defence traits. To clarify the effects of light on the development of multiple defence traits, the production of direct and indirect defence traits of young plants of Mallotus japonicus were examined experimentally under different light conditions.

METHODS

The young plants were cultivated under three light conditions in the experimental field for 3 months from May to July. Numbers of ants and pearl bodies on leaves in July were examined. After cultivation, the plants were collected and the developments of trichomes and pellucid dots, and extrafloral nectaries (EFNs) on the leaves were examined. On plants without nectar-collecting insects, the size of EFNs and the volume of extrafloral nectar secreted from the EFNs were examined.

KEY RESULTS

Densities of trichomes and pellucid dots did not differ significantly among the plants under the different light conditions, suggesting that the chemical and physical defences function under both high and low light availability. The number of EFNs on the leaves did not differ significantly among the plants under the different light conditions, but there appeared to be a trade-off between the size of EFNs and the number of pearl bodies; the largest EFNs and the smallest number of pearl bodies were found under high light availability. EFN size was significantly correlated with the volume of extrafloral nectar secreted for 24 h. The number of ants on the plants was smaller under low light availability than under high and moderate light availability.

CONCLUSIONS

These results suggest that direct defence traits function regardless of light conditions, but light conditions affected the development of indirect defence traits.