Estrogen Regulation Of CD147Expression In Normal Mammary Gland Development And Tumorigenesis

IntroductionBreast cancer is an endocrine related malignant tumor. Estrogen playsan important role in the development and progression of breast cancer.Metastasis is often the direct cause which makes the cancer patients succumb.Therefore prevention and treatment of metastasis is the key to reduce breastcancer mortality. However, the molecular mechanism of metastasis is still notfully understood. CD147belongs to the immunoglobulin superfamily, and is atransmembrane glycoprotein. It is able to induce the expression of severalmatrix metalloproteinases （MMPs） which play an essential role in themetastasis of cancer by degrading the stroma matrix. Over expression ofCD147has been demonstrated in many cancers. However, we know littleabout the expression regulation of CD147itself.The signal of estrogen is mediated by its receptor ER. There is twotypes of ER, i.e., ERα and ERβ. In this thesis, ER means ERα. In thenon-activated state, ER binds the heat shock protein （HSP) and exists in the cytoplasm. After binding with estrogens, the ER space conformation ischanged and it is transferred to the nucleus. The activated ER combines withERE sites in the target genes and starts transcription. ERE is the classic actionsite of ER. Besides ERE, ER can also act on the SP1binding site and AP1binding sites of target genes by combining with SP1and AP1and promote thetranscription of the target genes. In view of the fact that CD147promoterupstream sequence containing SP1protein binding sites, CD147should beone of the target genes of ER.This study aims to deep our understanding of the biological function ofCD147, estrogen and its receptor signaling system in breast cancer progression,and metastasis.ObjectivesTo explore estrogen regulation of CD147expression in human breastcancer, and the biological role of CD147in normal mammary gland breastcancer progression. To test the expression of CD147in uterus of adult miceafter spayed, in order to prove that CD147expression is regulated by ER andestrogen is the upstream signal. To examine the expression CD147in normalhuman mammary glands, ER positive breast cancer vs ER negative breastcancer.Methods1) Six female Kunming mice of8-week old were divided into two groups.Each group has three mice. One group was ovariectomized. Another groupwas Sham operated. After48hours of ovariectomy or sham operation, micewere sacrificed and uterus dissected out. Western blot was used to examineCD147protein levels of the uterus then. 2) Human breast cancer samples, twenty-two ER positive and eighteen ERnegative, were archived specimen from Department of Pathology of XijingHospital. Immunohistochemical staining was used to examime their CD147protein expression level.3) MCF-7human breast cancer cells were treated with estrogen24hrs. CD147mRNA levels were examined by qRT-PCR before and after treatment.Western blot was used to examine CD147protein levels.4) MCF-7cells were treated by estrogen. Detect the morphology of MCF-7cells by inverted microscope. Determine the metastasis of MCF-7cells byScratch assay.Results1) Western blot showed that CD147expression was decreased obviously in theuterus of ovariectomized mice after48hours.2) There is CD147expression in normal breast epithelial cell membrane.CD147expression is in breast cancer tissue and mainly in cancer cellsmembrane. And CD147expression in cancerous tissue edge is higher.CD147expression in ER positive cancerous tissue was significantly higherthan in the ER negative cancerous tissue.3) In the ER positive human breast cancer cells， the expression ofCD147mRNA and protein increased after treated by estrogen. And there wasno obvious effect in the ER negtive human breast cancer cells.4) MCF-7cells turned round without estrogen treated. The growth andmetastasis of MCF-7cells turned fast after estrogen treated.Conclusions1) CD147expression was reduced in the uterus of ovariectomized mice. It indicated that CD147expression was regulated by ER and estrogen was theupstream signal.2) There is CD147expression in normal breast epithelial cell membrane andmainly in cancer cells membrane. And CD147expression in canceroustissue edge is higher. CD147expression in ER positive cancerous tissue wassignificantly higher than in the ER negative cancerous tissue.3) Estrogen could activate the expression of CD147though ER to promotegrowth and metastasis of breast cancer.4) The shape of MCF-7cells became oval without estrogen treatment. Thegrowth and metastasis of MCF-7cells turned fast after estrogen treatment.