Nowadays women are sparing more efforts to understand what breast cancer is, how to prevent, early detection and cure of breast cancer. Breast cancer is the most commonly diagnosed cancer among women and it develops at any age and elder women have higher risks of getting breast cancer. Professor LIU Suling and her team demonstrate that a small RNA, MicroRNA-100 (miR-100), associates with proliferation and differentiation of breast cancer stem-like cells and inhibits growth and migration of breast cancer cells, which indicates a novel cure method of breast cancer.
According to US Breast Cancer Statistics, about 5-10% of breast cancers can be linked to gene mutations inherited from one’s mother or father while around 85% of breast cancers occur due to genetic mutations that happen as a result of the aging process and life in general, rather than inherited mutations.
MicroRNA (miRNA) is a kind of single-stranded non-coding RNA, usually encoded by endogenous genes and of 22 nucleotides. MiRNAs widely regulate gene expression and many cellular functions by specific base-pairing to target mRNA and thus initiating degradation of target mRNA or the inhibition of translation. Extensive literature has proved that abnormal regulation of miRNAs is closely related to development of cancer and new evidence shows that miRNAs play an important role in self-renewal and differentiation of stem cells via regulating the expression of key regulatory genes of stem cells.
Professor LIU proved that miR-100 involves in the breast cancer stem-like cell self-renewal. The expression level of miR-100 relates to the differentiation state of the cells and miR-100 expresses very lowly in breast cancer stem cells. The researchers treated breast cancer cells with tetracycline-inducible lentivirus to elevate expression of miR-100 in human cells, they found over expression of miR-100 decrease production of breast cancer stem-like cells. Further study indicates that miR-100 prevents proliferation of cancer cells in vitro and in mouse tumor xenografts through down-regulation of breast cancer stem-like cells regulatory genes like SMARCA5, SMARCD1 and BMPR2. Immediate miR-100 induction blocked tumor growth upon their orthotopic implantation or intracardiac injection. Clinically, they identified there is significant correlation between expression of miR-100 and patient survival.
Figure：mir-100 inhibits metastasis of SUM159 cells in vivo. SUM159 CTRL or SUM159 mir-100 were labeled with DsRed and cultured atop the chick CAM, a tissue whose stromal compartment is rich in interstitial collagens. After a 3-day culture period, control SUM159 cells rapidly cross the CAM surface and infiltrate the underlying stromal tissues.
The research indicates a new target to cope with breast cancer and provides scientists clue to find a novel treatment to save lives from breast cancer. The research entitled “microRNA100 inhibits self-renewal of breast cancer stem-like cells and breast tumor” was published online on Cancer Research on September 12, 2014.
(JI Jiaojiao, USTC News Center)
