Hydrogen sulfide (H₂S), once recognized only as a poisonous gas, is now considered the third endogenous gaseous transmitter, along with nitric oxide (NO) and carbon monoxide (CO). Multiple lines of emerging evidence suggest that H₂S plays positive roles in plant growth and development when at appropriate concentrations, including seed germination, root development, photosynthesis, stomatal movement, and organ abscission under both normal and stress conditions. H₂S influences these processes by altering gene expression and enzyme activities, as well as regulating the contents of some secondary metabolites. In its regulatory roles, H₂S always interacts with either plant hormones, other gasotransmitters, or ionic signals, such as abscisic acid (ABA), ethylene, auxin, CO, NO, and Ca²⁺. Remarkably, H₂S also contributes to the post-translational modification of proteins to affect protein activities, structures, and sub-cellular localization. Here, we review the functions of H₂S at different stages of plant development, focusing on the S-sulfhydration of proteins mediated by H₂S and the crosstalk between H₂S and other signaling molecules.

The development of multifunctional nano drug delivery carriers has been one of the most effective and prevailing approaches to overcome drug non-selectivity, low cell uptake efficiency and various side effects of traditional chemotherapy drugs. Herein, we report a novel doxorubicin (DOX)-loaded mesoporous silica nanoparticle (MSN) coated with polydopamine (PDA) and polyethylene glycol (PEG) (MSNs-DOX@PDA-PEG) for the treatment of breast cancer. In this system, PDA functions as a pH-sensitive gatekeeper to control the release of DOX from MSNs in response to pH-stimulus and PEG was further grafted on the surface of PDA to increase the stability and biocompatibility under physiological conditions. The in vitro release results suggested that MSNs-DOX@PDA-PEG exhibits a high sensitivity to low pH. A cellular uptake assay showed a high cellular uptake efficiency of MSNs-DOX@PDA-PEG compared to free DOX. Furthermore, MSNs-DOX@PDA-PEG also demonstrated an improved anti-cancer efficacy compared to free DOX both in vivo and vitro breast cancer experiments. Mechanistic studies revealed that MSNs-DOX@PDA-PEG causes a stronger pro-death autophagy compared to free DOX via inhibition of the AKT-mTOR-p70S6K signaling pathway. Taken in concert, our results suggest that the novel material MSNs-DOX@PDA-PEG may represent a promising nanoformulation for breast cancer treatment.

Non-small cell lung cancer (NSCLC) exhibits radioresistance to conventional rays, due to its DNA damage repair systems. NSCLC may potentially be sensitized to radiation treatment by reducing those factors that continuously enhance the repair of damaged DNA. In the present study, normal lung fibroblast MRC-5 and lung cancer A549 cells were treated with NU7026 and CGK733, which are inhibitors of the DNA-dependent protein kinase catalytic subunit (PKcs) and ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR), respectively, followed by exposure to X-rays and carbon ion irradiation. The cytotoxic activity, cell survival rate, DNA damage repair ability, cell cycle arrest and apoptosis rate of the treated cells were analyzed with MTT assay, colony formation assay, immunofluorescence and flow cytometry, respectively. The transcription and translation levels of the ATM, ATR and DNA-PKcs genes were detected by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. The results indicated that the radiosensitivity and DNA repair ability of A549 cells were reduced, and the percentages of apoptotic cells and those arrested at the G2/M phase of the cell cycle were significantly increased, following ionizing radiation with inhibitor-pretreatment. The expression levels of ATM, ATR, DNA-PKcs and phosphorylated histone H2AX, a biomarker for DNA double-strand breaks, were all upregulated at the transcriptional or translational level in A549 cells treated with carbon ion irradiation, compared with the control and X-rays-treated cells. In addition, the treatment with 5–50 µM NU7026 or CGK733 did not produce any obvious cytotoxicity in MRC-5 cells, and the effect of the DNA-PKcs-inhibitor on enhancing the radiosensitivity of A549 cells was stronger than that observed for the ATM and ATR-inhibitor. These findings demonstrated a minor role for ATM and ATR in radiation-induced cell death, since the upregulation of ATM and ATR did not rescue the A549 cells subjected to ionizing irradiation. Therefore, future studies on DNA-PKcs, ATM and ATR may lead to novel specific therapies that supplement general radiotherapy for the treatment of lung cancer.

The leaf explants from the eight-week-old Gentiana macrophyllaPall sterile seedlings were precultured for three days on Murashige and Skoog (MS) agar medium with 1 mg/l of 6-benzyladenine, and then...