Discovery, synthesis, and optimization of teixobactin, a novel antibiotic without detectable bacterial resistance.

Discovering new antibiotics with novel chemical scaffolds and antibacterial mechanisms presents a challenge for medicinal scientists worldwide as the ever-increasing bacterial resistance poses a serious threat to human health. A new cyclic peptide-based antibiotic termed teixobactin was discovered from a screen of uncultured soil bacteria through iChip technology in 2015. Teixobactin exhibits excellent antibacterial activity against all the tested gram-positive pathogens and Mycobacterium tuberculosis, including drug-resistant strains. Given that teixobactin targets the highly conserved lipid II and lipid III, which induces the simultaneous inhibition of both peptidoglycan and teichoic acid synthesis, the emergence of resistance is considered to be rather difficult. The novel structure, potent antibacterial activity, and highly conservative targets make teixobactin a promising lead compound for further antibiotic development. This review provides a comprehensive treatise on the advances of teixobactin in the areas of discovery processes, antibacterial activity, mechanisms of action, chemical synthesis, and structural optimizations. The synthetic methods for the key building block l-allo-End, natural teixobactin, representative teixobactin analogs, as well as the structure-activity relationship studies will be highlighted and discussed in details. Finally, some insights into new trends for the generation of novel teixobactin analogs and tips for future work and directions will be commented.

Astragaloside IV promotes keratinocyte proliferation and migration through upregulating lncRNA H19 recruited ILF3 to enhance the stability of CDK4 mRNA.

Skin is the first line of the body to resist pathogen invasion. A potentially fatal infection may result from problems with wound healing. Small molecule drugs like astragaloside IV (AS-IV) show pro-healing activities, but the mechanisms are not fully understood. Using real-time quantitative PCR and a western blot assay, the amount of gene expression was evaluated. The proliferation and migration of keratinocytes were determined by MTS and wound healing assay, respectively. The binding of lncRNA H19 to RBP protein ILF3 and the binding of ILF3 protein to CDK4 mRNA were confirmed by RNA immunoprecipitation. Treatment with AS-IV enhanced the expression of lncRNA H19, ILF3, and CDK4 and improved the proliferation and migration of keratinocytes HaCaT. Additionally, apoptosis of keratinocytes was attenuated by AS-IV. Further studies showed that both lncRNA H19 and ILF3 were important for AS-IV-mediated keratinocyte growth and migration. In addition, lncRNA H19 recruited ILF3 to increase CDK4 mRNA level and enhanced cell proliferation. We discovered a lncRNA H19/ILF3/CDK4 axis that is activated by AS-IV to promote keratinocyte migration and proliferation. These results elucidate the mechanism of action of AS-IV and justify its application in further application in wound healing treatment.

Impact of adequate lymph nodes dissection on survival in patients with stage I rectal cancer.

Background and Aims: The NCCN guidelines recommended an assessment of ≥ 12 lymph nodes (LN) as an adequate LN dissection (LND) for rectal cancer (RC). However, the impact of adequate LND on survival in stage I RC patients remained unclear. Thus, we aimed to compare the survival between stage I RC patients with adequate and inadequate LND. Methods: A total of 1,778 stage I RC patients in the SEER database from 2010 to 2017 treated with radical proctectomy were identified. The association between ≥ 12 LND and survival was examined using the multivariate Cox regression and the multivariate competing risk model referenced to < 12 LND. Results: Stage I RC patients with ≥ 12 LND experienced a significantly lower hazard of cancer-specific death compared with those with < 12 LND in both multivariate Cox regression model (adjusted HR [hazard ratio], 0.44, 95% CI, 0.29-0.66; P < 0.001) and the multivariate competing risk model (adjusted subdistribution HR [SHR], 0.45, 95% CI, 0.30-0.69; P < 0.001). Further, subgroup analyses performed by pT stage. No positive association between ≥ 12 LND and survival was found in pT1N0 RC patients (adjusted HR: 0.62, 95%CI, 0.32-1.19; P = 0.149; adjusted SHR: 0.63, 95%CI, 0.33-1.20; P = 0.158), whereas a positive association between ≥ 12 LND and survival was found in pT2N0 RC patients (adjusted HR: 0.35, 95%CI, 0.21-0.58; P < 0.001; adjusted SHR: 0.36, 95%CI, 0.21-0.62; P < 0.001). Conclusions: The long-term survival benefit of adequate LND was not found in pT1N0 but in pT2N0 RC patients, which suggested that pT2N0 RC patients should be treated with adequate LND and those with inadequate LND might need additional therapy.