Screening The Compounds With Anti-tumor And Anti-aging Activity From Congea Chinensis

Aging and tumorigenesis have always been the important subjects for human research.The pursuit of health and longevity has become a fashion today.However,in recent years,due to the worsening natural environment and social stress,the human cancer incidence and mortality rates stay at a high level.At the same time,the abuse of drugs and hormones during the anti-aging process make people susceptible to tumorigenesis.Aging shared common molecular mechanisms and played conflict role with the molecules in tumorigenesis.Therefore,seeking the balance between tumor and aging and using the double-sided sword of aging on tumor inhibition have been the new direction of aging research.The p53 gene,telomere and telomerase have played important roles in balancing aging and tumorigenesis.As an important cellular transcription factor,p53 is activated and stabilized in response to stress including DNA damage,exaggerate cellular proliferation signals.Once the signaling pathway is activated,p53 will regulate the expression of its down stream genes,inducing repairing,cell cycle arrest or apoptosis.The activation of oncogene will result to the activation of p19ARF,stabilized and activated p53,induce the cellular damage response status,and prevent the tumroigenesis.The telomerase activity is not detectable in normal adult human cells,and the length of telomere is limited.The telomere will be continuously shortening along with the cell division.When the length of telomere is short to certain degree,it will induce DNA damage response and induce cellular senescence or apoptosis.However,in tumor cells,the telomerase is activated and maintain the length of telomere,enable tumor cells the unlimited proliferation potential.Thus,telomerase is an important target in the prevention and treatment of tumor and aging-related disease.It has been shown that simultaneously increase of the expression level of p53 and p19ARF in mice could decrease the DNA damage in vivo,and the mice are resistant to tumorigenesis,thus elongate the lifespan.Further study revealed that if overexpressing the catalytic subunit of telomerase TERT,the aging of the mouse organs,such as skin and intestinal epithelia,is delayed obviously.The lifespan is elongated obviously without the elevation of tumor incidence.These results suggested that the simultaneously increase of the level of cell proliferation(telomerase)and the level of tumor inhibition(p53)might reach the goal of anti-aging and anti-tumor at the same time.Therefore,aim the activation of telomerase and p53,we might get the natural compounds with the activity of anti-aging and anti-tumor.Yunnan province is rich in biodiversity,which provided us abundant resources for medicinal plants.Researchers from the Yunnan Provincial Academy of Agriculture Science have established the bank for medicinal plants of Yunnan.Screening with the fluorescence reporter system established in the lab earlier,we got 7 kinds of medicinal plants that could activate p53 genes.Using SRB(Sulforhodamine B)assay,we tested the cytotoxicity and selectivity for tumor and normal cells after treating with the ethanol extracts from these plants.The results showed that the ethanol extract from Congea chinensis could selectively kill tumor cells and be less toxic to normal cells.Congea chinensis is well known as gardening ornamental plant,its medicinal function has not been reported.Congea chinensis located in the valley of rain forest in Menna county,Xishuangbanna,Yunnan.Congea chinensis is a kind of climbing bush,Branchlets densely grayish pilose.Petiole to 7 mm,pilose;leaf blade narrowly elliptic,5 cm,abaxially densely pilose,base subrounded to cordate,margin entire,apex acuminate;veins abaxially prominent,pilose when young.Cymes 5-7-flowered,densely grayish pilose;peduncle 1-2 cm;involucral bracts 4,narrowly oblong.Calyx campanulate,7-8 mm,outside densely white pilose,inside pubescent.Corolla grayish,ca.7 mm,tube cylindric.Stamens 4,long exserted.Ovary ca.2 mm,glabrous.By real-time PCR,we further tested the action of Congea chinensis extract on the expression of the reverse transcription enzyme of telomerase:TERT.The results showed that Congea chinensis extract dramatically increased the expression of TERT.Together we found that Congea chinensis extract could kill tumor cells and increase the expression of TERT,provided us a potential for balancing anti-aging and anti-tumor.We harvested large amount of Congea chinensis and tried to isolate the fractions from the extract and establish the screening protocol to screen the active site:Firstly we used SBR assay to screen the active factions that selectively killed tumor cells;Secondly we tested the action of these active factions on the TERT expression by real-time PCR;Then we tested the action of these active factions on the p53 expression by Western blotting assay.By this screening strategy,we have gotten the relatively purified active site of Congea chinensis:G2-7.In summary,the total extract of Congea chinensis and its active factions showed selective cytotoxicity to tumor cells.These characteristics could reduce the toxic side effect to normal cells,which is a common problem for the regular chemo-therapy drugs.Furthermore,the active fractions could kill tumor cells and elevate the telomerase at the same time,which provided the basis for balancing anti-aging and anti-tumor.