Inhibition Of Isoharringtonine On Triple Negative Breast Cancer

Triple negative breast cancer(TNBC)is malignant subtype of breast cancer,which is charactered by lack of ER(estrogen receptor),PR(progesterone receptor)and not over expression in HER2(human epidermal growth factor receptor 2)and often confer the patients with poor prognosis,metastasis and recurrence.For lack of the receptors above,the hormone therapy for TNBC is not available in clinical treatment.Neoadjuvant chemotherapy is common for treatment of TNBC.It is proposed the cancer stem cells(CSCs)are a subpopulation of stem-cell like cells in tumor.Just like the stem cells,the population of cell can maintain by self-renew and differentiate into various types of cell,contributing to heterogeneity.For the ability to initiate cancer,the cells are also called tumor-initiation cells(TICs),the cells are thought to be underlying cause of tumor development,metastasis and recurrence as so far.In term of treatment for cancer,the researches on cancer stem cell and reagents targeting at CSCs are centered on.Similar to stem cells,maintenance of CSCs is associated to the pathways as below:Wnt pathway,notch pathway,Hedgehog pathway,TGF-?/BMP pathway,in addition with Jak/Stat pathway.For example,Wnt pathway regulates expressions of a serious genes related to stemness like NANOG,SOX2 and OCT4,and transcription of NANOG is also activated by via binding of STAT3 to the promoter,then maintains the stemness of CSCs.Jak/Stat pathway is necessary for breast cancer stem cells(BCSCs)marked by CD44+CD24-.IHT(isoharringtonine)is one of Cephalotaxus alkaloids,which is isolated from Cephalotaxus,most common in China.IHT is analogous to HHT(homoharringtonine)in chemical structures,various researches are for IHT,but seldom for IHT.We invested the effect of IHT on TNBC and potential mechanism,taking consideration the difference.As it is reported,paclitaxel used in the Neoadjuvant chemotherapy for treatment of TNBC can lead to enrichment of BCSCs,then contribute to the heterogeneity of tumor with chemical resistance and recurrence.Breast cancer stem cell contribute to tumor initiation,metastasis,chemical and radio resistance,tumor immune escape and reforming the cancer niche,then finally recurrence.Researchers have been taking efforts to develop treatment aim at breast cancer stem cells to overcome the problem facing us.In our research,we test effect of IHT on cell proliferation by MTS,cell migration by wound healing assay,and invested inhibition of IHT on breast cancer stem cell via FACS,then confirmed our results by soft-agar clone and tumorsphere formation assay,finally,revealed the mechanism by western blot and RT-qPCR.Our result presented that IHT could inhibited proliferation and migration of TNBC cells at concentrations ranging from 0 nM to 300 nM for HOC 180 and 0 nM to 600 nM for HCC1937,when the treatment was for 24 h,meanwhile,the BCSCs were also reduced,accordance with reduction of formation in soft-agar clone and tumosphere,with cells treated with IHT at the concerntions.We also revealed that IHT down regulated p-STAT3,the same as HHT,when treating cells with IHT as that for cell proliferation assay,and transcription of NANOG,one of down stream genes of STAT3 and related to sternness,was also inhibited.We inferred that IHT inhibited BCSCs in TNB via down regulation of STAT3/NANOG pathway,causing inhibition on cell proliferation and migration though the protein levels of Cyclin and EMT marker not in accordance with each other.Although similar to HHT in mechanism,but IHT did not induced apoptosis.IHT alone was not effective for breast cancer in nude mouse.