KDM3A promotes oral squamous cell carcinoma cell proliferation and invasion via H3K9me2 demethylation-activated DCLK1.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is a frequently-diagnosed malignancy with high potential for proliferation and invasion. Histone methylation is known as a crucial mechanism that regulates pathological processes in various cancers, including OSCC. OBJECTIVE: This study sought to delve into the molecular mechanism of lysine demethylase 3 A (KDM3A) in OSCC cell proliferation and invasion. METHODS: Expression levels of KDM3A, lysin-9 of di-methylated histone H3 (H3K9me2), and doublecortin-like kinase 1 (DCLK1) in cells were determined by reverse-transcription quantitative polymerase chain reaction or Western blot analysis. Cell proliferation and invasion were evaluated by cell counting kit-8, colony formation, and Transwell assays. The enrichment of KDM3A and H3K9me2 on the DCLK1 promoter was determined by chromatin immunoprecipitation assay. The functional rescue experiment was performed with DCLK1 overexpression vector and si-KDM3A in CAL-27 and SCC-9 cells. RESULTS: KDM3A was elevated in OSCC cells. KDM3A knockdown suppressed OSCC proliferation and invasion, along with increased H3K9me2 level in OSCC cells. KDM3A and H3K9me2 were enriched on the DCLK1 promoter and inhibiting H3K9me2 improved DCLK1 expression levels. DCLK1 overexpression neutralized the inhibition of KDM3A knockdown on OSCC proliferation and invasion. CONCLUSIONS: KDM3A facilitated OSCC proliferation and invasion by eliminating H3K9me2 to upregulate DCLK1 expression levels.

Effects of cadmium and flooding on the formation of iron plaques, the rhizosphere bacterial community structure, and root exudates in Kandelia obovata seedlings.

In the rhizosphere, plant root exudates (REs) serve as a bridge between plant and soil functional microorganisms, which play a key role in the redox cycle of iron (Fe). This study examined the effects of periodic flooding and cadmium (Cd) on plant REs, the rhizosphere bacterial community structure, and the formation of root Fe plaques in the typical mangrove plant Kandelia obovata, as well as the relationship between REs and Fe redox cycling bacteria. Based on two-way analysis of variance, flooding and Cd had a considerable effect on the REs of K. obovata. DOC, NH4+-N, NO3--N, dissolved inorganic phosphorus, acetic acid, and malonic acid concentrations in REs of K. obovata increased considerably with the increase of Cd concentration under 5 and 10 h flooding conditions. Fe plaque development in the plant root was stimulated by flooding and Cd, although flooding was more effective. After Cd treatment, the ways in which Fe-oxidizing bacteria (FeOB) and Fe-reducing bacteria (FeRB) were enriched in the rhizosphere and rhizoplane of plants were different. Thiobacillus and Sideroxydans (dominant FeOB) were more abundant in the plant rhizosphere, whereas Acinetobacter (dominant FeRB) was more abundant in the rhizoplane. Cd considerably decreased the relative abundance of unclassified_f_Gallionellaceae in the rhizosphere and rhizoplane but dramatically enhanced the relative abundance of Thiobacillus, Shewanella, and unclassified_f_Geobacteraceae. Unclassified_f_Geobacteraceae and Thiobacillus exhibited substantial positive correlations with citric acid and DOC in REs in the rhizosphere and rhizoplane but strong negative correlations with Sideroxydans. The findings indicate that Cd and flooding treatments may play a role in the production and breakdown of Fe plaque in K. obovata roots by affecting the relative abundance of Fe redox cycling bacteria in the rhizosphere and rhizoplane.

Ferrous iron facilitates the formation of iron plaque and enhances the tolerance of Spartina alterniflora to artificial sewage stress.

The ferrous iron (Fe2+) facilitates the formation of root Fe plaque of wetland plants, but its effect on the tolerance of wetland plants to artificial sewage stress has been seldom reported. In this study, the influences of Fe2+ on the formation of Fe plaque and its effects on the tolerance of Spartina alterniflora to artificial sewage stress were investigated. The artificial sewage stress decreased the plant height and chlorophyll content and significantly increased the MDA content in leaves. The symptoms of these stresses were alleviated with increasing Fe2+ concentration accompanied by significant increase in leaf alcohol dehydrogenase activity. The increase of Fe2+ concentration significantly increased the root Fe plaque content and reduced the accumulation of toxic metals in leaves of S. alterniflora. These results support our hypothesis that the exogenous Fe2+ supply may enhance the stress resistance of S. alterniflora to artificial sewage containing heavy metals.

Decomposition of Spartina alterniflora and concomitant metal release dynamics in a tidal environment.

The decomposition of salt marsh plants is affected by the variation of physiochemical factors caused by the change of tide level. In the present study, plant tissues of Spartina alterniflora from controlled metal exposure experiments were subjected to a field decomposition trial at different tidal levels in a tidal flat of Chongming Island, Shanghai. The contents of the metals and Pb stable isotope ratios of the plant litter and the adjacent sediment were followed. The mass loss rate of the root and leaf litters of S. alterniflora decreased with the increase of burial time. Leaf had the highest decomposition rate (0.009 day-1 to 0.020 day-1) compared to that of the roots (0.004 day-1 to 0.005 day-1) and stems (0.002 day-1 to 0.006 day-1). Leaf had the highest decomposition rate possibly due to the significantly lower C/N ratio (16.0-44.6) compared to that of the roots (32.8-88.9) and stems (43.7-120.9). The mass loss rate of the roots and leaves of S. alterniflora was higher in the high tidal marsh than that in the low tidal marsh, especially at the late stages of decomposition. The concentrations of metals in leaf litter of S. alterniflora increased, whereas the pools of metals in most of the plant litters decreased significantly with the increasing of the decomposition time. The ratios of 207Pb/206Pb and 208Pb/206Pb in the root litters decreased significantly in the first 290 days of decomposition and then increased significantly at Day 350, while the Pb isotope ratios in adjacent sediment showed no significant changes. Fast mass loss of plant litters induced the significant decrease in metals' pools at early stages of decomposition, and release of the plant tissue Pb was greatly inhibited due to the slowed mass loss at the late stages of decomposition.

Formation of iron plaque in the roots of Spartina alterniflora and its effect on the immobilization of wastewater-borne pollutants.

Iron plaque (IP) plays an important role in the absorption of heavy metals (HMs) and nutrients in wetland plants. The present study aims to investigate the effect of IP in Spartina alterniflora on the immobilization of wastewater borne HMs and nutrients. The physiological responses and effect of IP formation on the uptake of HMs, nitrogen (N), and phosphorus (P) were studied in S. alterniflora subjected to different synthetic wastewater (SW) levels and waterlogging durations. Results showed that IP formed in roots of S. alterniflora increased significantly with increasing SW concentration but decreased under prolonged waterlogging. Increasing the waterlogging time enhanced the alcohol dehydrogenase activity and the ethylene content in the roots of S. alterniflora. HMs including Cu, Pb, and Cr, did not significantly accumulate in the IP, despite that the IP content increased with the increasing of SW levels. The SEM-EDX analysis revealed that IP formed on the surface of S. alterniflora did absorb HMs such as Cu, Zn, and Cr. At a fixed level of SW, the amount of HMs that accumulated in the DCB extract was substantially proportional to the IP concentration in the root. Increasing of the SW level enhanced the accumulation of P in the leaves and roots of S. alterniflora. In conclusion, IP formed on S. alterniflora helped immobilize SW pollutants, including HMs and P, and the formation of IP and its effect on pollutant immobilization were influenced by the waterlogging conditions.

Combined effect of water inundation and heavy metals on the photosynthesis and physiology of Spartina alterniflora.

The frequency and duration of tidal flooding significantly influence the bioavailability of heavy metals (HMs) in sediment and hence exert toxicological effects on coastal wetland plants. In this study, the combined effects of different water inundation times (3, 6, 9, and 12 h) and HMs (Cu, Zn, Pb, and Cr) on the photosynthesis and physiology of Spartina alterniflora were investigated under greenhouse conditions. Results showed that S. alterniflora was somehow tolerant to the combined HMs treatments, and only the highest level of HM treatment decreased leaf chlorophyll content. Furthermore, the plants did not show any signs of victimization. Different times of water inundation with HMs did not exert any significant effect on the malonaldehyde (MDA) and chlorophyll contents in the leaves of S. alterniflora at day 20. Prolonged water inundation time at day 60 significantly reduced leaf chlorophyll content with the decrease in leaf photosynthetic rate, which was accompanied by a significant increase in the intercellular concentration of CO2. At day 60, abscisic acid dose-dependently increased along the different water inundation times, indicating that this phytohormone is involved in plant responses to flooding stress. Peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), showed different responses to the combined treatment of water inundation and HMs at different times. At day 20, the long duration of water inundation and HMs treatments (9 h+HMs and/or 12 h+HMs) significantly increased enzyme activity in the leaves compared with the control group (6 h). At day 60, the POD and SOD activities in the leaves of S. alterniflora decreased with prolonged water inundation time, and root APX activity significantly decreased compared with the 6 h water inundation treatment.

Iron plaque formation and heavy metal uptake in Spartina alterniflora at different tidal levels and waterlogging conditions.

Tidal flat elevation in the estuarine wetland determines the tidal flooding time and flooding frequency, which will inevitably affect the formation of iron plaque and accumulations of heavy metals (HMs) in wetland plants. The present study investigated the formation of iron plaque and HM's (copper, zinc, lead, and chromium) accumulation in S. alterniflora, a typical estuarine wetland species, at different tidal flat elevations (low, middle and high) in filed and at different time (3, 6, 9, 12 h per day) of waterlogging treatment in greenhouse conditions. Results showed that the accumulation of copper, zinc, lead, and chromium in S. alterniflora was proportional to the exchangeable fraction of these metals in the sediments, which generally increased with the increase of waterlogging time, whereas the formations of iron plaque in roots decreased with the increase of waterlogging time. Under field conditions, the uptake of copper and zinc in the different parts of the plants generally increased with the tidal levels despite the decrease in the metals' exchangeable fraction with increasing tidal levels. The formation of iron plaque was found to be highest in the middle tidal positions and significantly lower in low and high tidal positions. Longer waterlogging time increased the metals' accumulation but decreased the formation of iron plaque in S. alterniflora. The binding of metal ions on iron plaque helped impede the uptake and accumulation of copper and chromium in S. alterniflora.