Research Of Dendrobtum Candidum Inhibiting Effect On Breast Cancer Cell Proliferation

Breast cancer is a kind of malignant carcinoma occurs in breast glandulartissues. Its morbidity shows an increasing trend every year.99%breast cancer patientsare female, which makes it a common carcinoma treating women’s physical andmental health. Its incidence has obvious hereditary tendency. In situ breast cancer is notfatal; however, breast cancer cells lost the normal cell-cell contact as in normal cells,the linkage between breast cancer cells becomes loose and easy to come off the tumortissue. Once it shed from tumor tissue, circulating tumor cells can spread the wholebody with blood or lymph, forming metastases, thereby endangering lives.Cyclin-dependent kinase (CDK) is a serine/threonine kinase family associatedwith cell cycle progression. All different CDK molecules contain a similar kinasedomain, which a conserved sequence, PSTAIRE, and it can mediated the combinationof kinases and cyclin. When CDK and cyclin binds, it will trigger the kinase activity,thus, it is called cyclin-dependent kinases. CDK triggers the cell cycle throughchemical activation of serine/threonine protein. It synergically interacts with cyclinto form a heterodimer. CDK is the catalytic subunit, and cyclin is the regulatorysubunit, which is an important regulation factor in cell cycle. Different cyclin-CDKcomplexes catalyze the phosphorylation of different substrates to achieve thepromotion and transformation of the different phases within the cell cycle.They activate and phosphorylate corresponding substrates in turn along the cellcycle, activated CDK1can phosphorylate the target protein to produce thecorresponding physiological effects, such as the lamin phosphorylation leads to thedisintegration and disappearance of the nuclear membrane and H1phosphorylationleads to chromosome condensation et al. The final results of these effects guaranteethe orderly ongoing of every cell cycle in every cells. Therefore, CDK kinases andtheir regulators are also known as the cell cycle engine. CDK activity depends on itspositive regulatory subunit cyclin sequentially expression and the concentration of thenegative regulatory subunit CDI (dependent kinase inhibitor, CDK inhibiting factor). Meanwhile, CDK activity is also regulated by oncogenes and tumor suppressor genes.It can be inferred that the increase of CDK activity in human breast cancer cells is oneof the reasons that cancer cells proliferate in a high speed. Therefore CDK is a targetof inhibiting breast cancer cell proliferation. Exploring CDK inhibitors is an effectiveway of developing treatment for breast cancer.Dendrobium candidum is a traditional Chinese medicine, and its knownpharmacological effects are promoting glandular secretion and organ movement,hypoglycemic effect and enhancing the body immunity. Some recent studies showthat Dendrobium contains a variety of reactive phenanthrene and phenolic compounds,which can reduce the proliferation of a variety of malignant cells in lung cancer,stomach cancer, esophageal cancer, colon cancer and prostate cancer. Thus weconclude that it may have inhibition effect in breast cancer cell proliferation. Afterusing the extract of Dendrobium to treat human breast cancer cells, we foundDendrobium extract can significantly decrease the viability of breast cancer cells. Wecultured breast cancer cells in96-well plates, about5000cells per well, then addedDendrobium extract with different concentrations and incubated for different hours. Itcan be detected that compared to the control group, the cancer cells cultured withDendrobium extract exhibited a significant decrease in number. This shows that theDendrobium does inhibit breast cancer cell proliferation.We thus further speculated Dendrobium inhibited breast cancer cell proliferationthrough affecting the activity of the CDK in breast cancer cells. We reversetranscribed mRNA into cDNA, and by RT-qPCR method, we designed specificprimers and added a fluorescent molecular probes. When the cDNA of CDKreplicated, the fluorescent signal will enhance. So by comparing the fluorescenceintensity we can detect the amount of mRNA expression of CDK in a cell after cellexposed to Dendrobium extract.