Roflumilast inhibits tumor growth and migration in STK11/LKB1 deficient pancreatic cancer.

Pancreatic cancer is a malignant tumor of the digestive system. It is highly aggressive, easily metastasizes, and extremely difficult to treat. This study aimed to analyze the genes that might regulate pancreatic cancer migration to provide an essential basis for the prognostic assessment of pancreatic cancer and individualized treatment. A CRISPR knockout library directed against 915 murine genes was transfected into TB 32047 cell line to screen which gene loss promoted cell migration. Next-generation sequencing and PinAPL.py- analysis was performed to identify candidate genes. We then assessed the effect of serine/threonine kinase 11 (STK11) knockout on pancreatic cancer by wound-healing assay, chick agnosia (CAM) assay, and orthotopic mouse pancreatic cancer model. We performed RNA sequence and Western blotting for mechanistic studies to identify and verify the pathways. After accelerated Transwell migration screening, STK11 was identified as one of the top candidate genes. Further experiments showed that targeted knockout of STK11 promoted the cell migration and increased liver metastasis in mice. Mechanistic analyses revealed that STK11 knockout influences blood vessel morphogenesis and is closely associated with the enhanced expression of phosphodiesterases (PDEs), especially PDE4D, PDE4B, and PDE10A. PDE4 inhibitor Roflumilast inhibited STK11-KO cell migration and tumor size, further demonstrating that PDEs are essential for STK11-deficient cell migration. Our findings support the adoption of therapeutic strategies, including Roflumilast, for patients with STK11-mutated pancreatic cancer in order to improve treatment efficacy and ultimately prolong survival.

HbMYB44, a Rubber Tree MYB Transcription Factor With Versatile Functions in Modulating Multiple Phytohormone Signaling and Abiotic Stress Responses.

The vital roles of R2R3-MYB transcription factors (TFs) in regulating stress response and phytohormone signaling have been thoroughly studied in numerous plant species, but the functions of these TFs in rubber tree are poorly understood. Rubber tree is the most important source of natural rubber but often suffers from various abiotic and biotic stresses that cause severe yield losses each year. In this study, we reported a novel MYB44 gene in rubber tree (named HbMYB44) and revealed its biological function. HbMYB44 was highly similar to AtMYB44 and clustered into subgroup 22. Transient expression indicated that HbMYB44 is a nuclear localized protein and displays transactivation activity at the C-terminus. HbMYB44 was ubiquitously expressed in rubber tree, and its expression was strongly induced by multiple phytohormones, drought stress, wounding, and H2O2 treatments. Furthermore, overexpression of HbMYB44 in Arabidopsis (OE) demonstrated that OE plants significantly enhanced stress tolerance, i.e., salt stress, osmotic stress, and drought stress. Additionally, HbMYB44 promoted recovery from root growth inhibition of OE plants caused by exogenous phytohormones (including abscisic acid, methyl jasmonic acid, gibberellic acid 3, and salicylic acid), but the opposite effect was present in response to ethephon. Interestingly, HbMYB44 increased the expression of its homologous genes and interacting protein-encoding genes in OE plants. Overall, HbMYB44 plays versatile functions in modulating multiple phytohormone signaling pathways and stress tolerance.

Identification of a Ribose-Phosphate Pyrophosphokinase that Can Interact In Vivo with the Anaphase Promoting Complex/Cyclosome.

5-Phospho-d-ribosyl-1-diphosphate (PRPP) synthase (PRS) catalyzes the biosynthesis of PRPP, which is an important compound of metabolism in most organisms. However, no PRS genes have been cloned, let alone studied for their biological function in rubber tree. In this study, we identify a novel protein (PRS4) that interacts in vivo with rubber tree anaphase promoting complex/cyclosome (APC/C) subunit 10 (HbAPC10) by yeast two-hybrid assays. PRS4 has been cloned from rubber tree and named as HbPRS4. Blastp search in the genome of Arabidopsis thaliana showed that HbPRS4 shared the highest similarity with AtPRS4, with 80.71% identity. qRT-PCR was used to determine the expression of HbPRS4 in different tissues and under various treatments. HbPRS4 was preferentially expressed in the bark. Moreover, the expression level of HbPRS4 was significantly induced by the proteasome inhibitor MG132 treatment, suggesting it might be regulated by the ubiquitin/26S proteasome pathway. The amount of HbPRS4 transcript was obviously decreased after mechanical wounding and abscisic acid (ABA) treatments, while a slight increase was observed at 24 h after ABA treatment. HbPRS4 transcript in the latex was significantly upregulated by ethephon (ET) and methyl jasmonate (MeJA) treatments. These results suggested that HbPRS4 may be a specific substrate of HbAPC10 indirectly regulating natural rubber biosynthesis in rubber tree.

Effect of propofol on generation of inflammatory mediator of monocytes.

OBJECTIVE: To evaluate the effect of propofol with different concentrations on the expression of inflammatory mediators of interleukin and tumor-necrosis factor-α (TNF-α) by stimulating the mouse primary monocytes and human monocytic cell line with lipopolysaccharide (LPS) and also discuss the effect of propofol on the secretion of inflammatory mediator and its possible molecular mechanism. METHODS: The mononuclear cells of mouse spleen were separated and then purified to obtain the primary monocytes. The dose-effect relationship of production of pro-inflammatory cytokines by monocytes which were stimulated by LPS, namely the monocytes were stimulated by the dose of 0-500 ng/mL for 24 h. ELISA was employed to detect the concentration of IL-6, IL-8 and TNF-α. The effect of propofol on the secretion of above pro-inflammatory cytokines by the monocytes was observed. Cells were divided into the control group, the 0.1% DMSO group, the LPS group and the treatment group with LPS + different dose of propofol (propofol 1-100 µg/mL). ELISA was employed to detect the concentration of IL-6, IL-8 and TNF-α. The change in the expression of important signaling molecules in Toll-like receptor and NF-κB signaling pathway was detected after THP-1 cells were treated with propofol. RESULTS: The concentration of TNF-α was (3863 ± 153) pg/mL after 12 h of stimulation by LPS and then its concentration was decreased gradually. But the concentration of IL-6 and IL-8 was relatively high after 24 h of stimulation by LPS, (5627 ± 330) pg/mL and (1626 ± 200) pg/mL, respectively. The propofol could inhibit the expression of IL-6, IL-8 and TNF-α caused by LPS. After the intervention treatment of 50 µg/mL propofol, the concentration of IL-6, IL-8 and TNF-α was significantly decreased (P < 0.01). CONCLUSIONS: The propofol can inhibit the expression of TLR-4 and NF-κB to inhibit the activation of p38 and the expression of pro-inflammatory cytokines.