BackgroundCombretastatin A4 (CA4) is a potential therapeutic candidate for a variety of human cancer treatments. However, the inhibitive effects of CA4 on thyroid cancer cells are still not well-clarified. This study aimed to investigate the potential effect of CA4 on thyroid cancer cells, as well as underlying mechanism.Material/MethodsHuman thyroid papillary carcinoma cell line TPC1 was pre-treated with 5 concentrations of CA4 (0, 1, 2, 5, or 10 μM) for 2 h. Cell proliferation was determined by 3-(4, 5-dimethyl-2- thiazolyl)-2, 5-diphenyl -2-H-tetrazolium bromide (MTT) assay. Cell migration and invasion were detected by a modified Boyden chamber assay. Moreover, cell apoptosis was detected by terminal deoxynucleotidyl (TUNEL) staining assay and flow cytometry method. Western blot analysis was performed to determine the expression changes of epithelial-mesenchymal transition (EMT)-related proteins and phosphatidylinositol-3-kinase/serine/threonine kinase (PI3K/Akt) signaling pathway proteins.ResultsCA4 significantly inhibited the cell proliferation, migration, and invasion, and significantly promoted cell apoptosis in a dose-dependent manner compared with the control group. The EMT-related protein levels of N-Cadherin, Vimentin, Snail1, Slug, Twist1, and ZEB1 were significantly decreased by CA4, while E-cadherin had no significant difference compared with the control group. Moreover, PI3K/Akt signaling pathway protein levels of p-PI3K and p-Akt were significantly decreased, whereas PI3K and Akt had no significant differences compared with the control group.ConclusionsCA4 can inhibit proliferation, migration, and invasion and promote apoptosis of TPC1 cells. These effects might be through the PI3K/Akt signaling pathway. CA4 may be a potential therapeutic target for the treatment of thyroid cancer.

The runoff threshold is one of the important parameters in hillslope hydrology. Information on the combined roles of rainfall types and antecedent soil moisture in the runoff generation threshold is still scarce. Therefore, we linked the runoff generation behaviours of a 150‐m hillslope with rainfall types and antecedent soil moisture conditions during a 4‐year observation period between January 2017 and December 2020 in the red soil region of China. We found that the surface runoff of a hillslope could be modelled with a relatively high accuracy using HYDRUS 1D. Rainfall event types, classified into four types (I, II, III and IV) using a machine learning based k‐means clustering algorithm, significantly affected the modelling accuracy of runoff. The prediction accuracy decreased as the level of rainfall type increased, with R2 decreasing from 0.93 for type I to 0.41 for type IV and RMSE increasing from 0.0082 to 0.025 italiccm3italiccm−3 accordingly. The scope of the runoff threshold, represented by antecedent soil water storage of 0–30 cm and event rainfall amount (ASW+P), ranged between 97 and 139 mm. That is, when ASW+P was lower than the lower limit, no runoff occurred in all of the rainfall events, and runoff would be generated without considering the hydrological conditions if ASW+P was higher than 139 mm. The driving factors of runoff generation were strongly dependent on the classified rainfall types. Hourly maximum rainfall intensity was the main contributor to runoff generation for the relatively slight rainfall events (i.e., types I and II). The rainfall amount, however, played a dominant role for the rainfall types with larger amounts and intensities (i.e., types III and IV). These findings provide insights into the method of determining runoff thresholds as well as the inner mechanisms of runoff generation behaviours at the hillslope scale under regions with similar climatic and hydrological conditions to the present study. Highlights Heavy rainfall events were the main error sources of runoff modelling. The threshold of runoff generation was identified by the combination of antecedent soil moisture and rainfall. Threshold scope of runoff generation ranged between 97 and 139 mm. Rainfall classification is valuable in understanding runoff generation behaviours. Runoff driving factors depended on rainfall types.

Tillage practices significantly influence soil nutrient retention, soil structure, and stability. However, the impact of tillage practices on soil stability and erosion resistance through the perturbation approach of soil structure remains unclear. This study aimed to establish universal principles across slope surface and soil profile scales. We evaluated the effects of various tillage practices, including conventional tillage (CT), soil compaction (CM), subsoil tillage (ST), no tillage (NT), and subsoil tillage and soil compaction (SCM) on soil stability and erosion resistance in China’s red soil hilly region. Soil stability, erosion resistance, and other soil properties were quantified using field surveys and laboratory experiments. We discovered significant variations in soil aggregate stability (SAS), wet aggregate stability (WAS), soil mechanical stability (SMS), and soil erodibility (SE) among the five tillage methods. The K factor’s average value indicated that the 0–40 cm soil layer was more erodible for CT (0.472) than for other methods, with NT (0.26) being the least erodible. NT (0.43) was the most effective treatment for reducing SE, while SCM (0.41) enhanced soil fertility, controlled SE, and mitigated machinery-induced soil compaction risks. CM (0.38) maintained soil stability without improving the soil nutrient storage, while ST (0.33) improved the soil stability such as alleviating the soil hardening caused by CM. The results provide reference parameter values for selecting appropriate tillage methods to decrease soil degradation and erosion while enhancing the soil productivity in a red soil hilly region.