Antitumor Activity And Mechanism Of Two Exopolysaccharide From Microalgae

Microalgal polysaccharides are one of the most important physiological active substances in microalgae and have become a new drug resource in tumor treatment.In this study,the toxicity and growth inhibition of Chlorella sp.exopolysaccharide?CEPS?and Dunaliella salina exopolysaccharide?DsEPS?on cervical cancer cells?Hela?were analyzed,and the mechanism of their antitumor activity was revealed by transcriptome analysis.The results showed that both CEPS and DsEPS could inhibit Hela cell proliferation,reduce cell viability and change cell morphology.The results of inhibition rate showed that at the concentration of 1.0 mg/ml,both of them had higher inhibition rate on Hela cells than IC₅₀,but had no toxic side effects on normal Vero cells.The analysis of apoptotic rate showed that the spontaneous apoptotic rate of Hela cells was 5.42%;when the concentration of CEPS and DsEPS was 1 mg/mL,the apoptotic rates corresponding to CEPS were37.34%,42.26%,45.1%and 39.78%,40.15%,43.56%to DsEPS at different time?24h,48h,72h?,respectively.Transcriptome analysis showed that there were 1894differentially expressed genes between the control group and the CEPS group,of which 1076 were up-regulated and 818 were down-regulated;there were 2032differentially expressed genes?DEGs?between the control group and the DsEPS group,of which 1132 were up-regulated and 900 were down-regulated.GO functional annotation analysis showed that 63 GO classifications were generated in CEPS group and 62 GO classifications were generated in DsEPS group,while the results from GO functional classification showed that cell processes,single-organism process and biological regulation were the main types of biological processes,and binding was the main type of molecular functions.At the same time,many DEGs are enriched in biological adhesion,reproductive process,signaling and other items,confirming that the function of differentially expressed genes are closely related to cell proliferation,signal transduction,cell adhesion and other important functions.KEGG enrichment analysis showed that 43 metabolic pathways were significantly different between CEPS group and control group?p<0.05?,38 metabolic pathways were significantly different between DsEPS group and control group;many signal transduction pathways related to tumors were significantly enriched,including TNF signaling pathway,MAPK signaling pathway,VEGF signaling pathway,Ras signaling pathway,cAMP signaling pathway and PI3K-Akt signaling pathway,etc.The protein interaction network was constructed by DEGs,and the PPI network of CEPS consisted of 279 nodes with 13 hub genes;while the PPI network of DsEPS group consisted of 161 nodes with 10 hub genes calculated;and it was found that the common hub genes of CEPS group and DsEPS group formed a local network,including PTPN11,RSAD2,ISG15,IFIT1,MX2,IFIT2.OASL,OAS1,JUN,OAS2,XAF1,ISG20,and IRF9,most of these hub genes involved in the development of cancer.To validate the transcriptome sequencing results,13 DEGs were selected from different signaling pathways for real-time fluorescence quantitative PCR?qPCR?,and the qPCR results were consistent with the trend of differential expression of transcriptome sequenced genes,indicating that the transcriptome sequencing results were true and effective.This study shows that CEPS and DsEPS can be used as potential drug molecules for subsequent interventional treatment of cancer.