ABSTRACT
Due to the complexity of tumor pathology, the demand for the combined use of multiple drugs in clinical treatment has become increasingly clear-cut. Multi-drug combination can act on multiple pathways and multiple targets simultaneously to exert synergistic effects. However, the current delivery strategy for multi-drug combination still needs to be optimized. Nano-drug delivery systems can carry drugs to overcome physiological and pathological barrier to target tumor tissues and cells, achieve the goal of continuous, controllable, and targeted delivery, and enhance the efficacy of anti-tumor synergism and detoxification. To meet the new requirements for smarter and more accurate antitumor multi-drug combinational therapy, the nano-drug delivery system has been well-designed to realize more functions. For instance, delivery of multiple drugs in accurate proportions and doses can make the multi-drug synergistic effect more precise; stimulus-responsive drug release can improve selectivity and reduce side effects; controlling the time-course relationship of multiple drugs can realize sequential drug combination effect. It has shown broad prospects in the field of tumor multidrug therapy and has become one of the new directions of research and development. This article reviews the recent developments in the application of tumor drug combination therapy strategies and their delivery systems, and analyzes the new requirements and challenges of multidrug combination for the development of nano-drug delivery systems.
ABSTRACT
Objective·To investigate the function of sahH gene in exopolysaccharides synthesis of Streptococcus mutans LuxS null strain. Methods·sahH+luxS-SmUA159 was constructed by introducing sahH gene into Streptococcus mutans LuxS null strain,while PIB169+luxS-SmUA159 and its wild strain SmUA159 were used as vector control and blank control. Real-time qPCR and anthrone test were performed to investigate the differences in exopolysaccharides synthesis among sahH+luxS-SmUA159, PIB169+luxS-SmUA159 and the wide-type strain SmUA159. Results·The transcriptional levels of gtfA and gtfD were upregulated in the sahH+luxS-SmUA159,compared to SmUA159 and PIB169+luxS-SmUA159(both P<0.05),but there was no statistical difference in the transcriptional levels of gtfB and gtfC.The results of the anthrone test showed exopolysaccharides synthesis of the three groups was also similar. Conclusion·sahH gene affects the expression of some genes related to exopolysaccharides synthesis,but it has little effect on the whole content of bacterial exopolysaccharides.