Mevalonate metabolism regulates Basal breast cancer stem cells and is a potential therapeutic target

There is increasing evidence that breast tumors are organized in a hierarchy, with a subpopulation of tumorigenic cancer cells, the cancer stem cells (CSCs), which sustain tumor growth. The characterization of protein networks that govern CSC behavior is paramount to design new therapeutic strategies targeting this subpopulation of cells. We have sought to identify specific molecular pathways of CSCs isolated from 13 different breast cancer cell lines of luminal or basal/mesenchymal subtypes. We compared the gene expression profiling of cancer cells grown in adherent conditions to those of matched tumorsphere cultures. No specific pathway was identified to be commonly regulated in luminal tumorspheres, resulting from a minor CSC enrichment in tumorsphere passages from luminal cell lines. However, in basal/mesenchymal tumorspheres, the enzymes of the mevalonate metabolic pathway were overexpressed compared to those in cognate adherent cells. Inhibition of this pathway with hydroxy-3-methylglutaryl CoA reductase blockers resulted in a reduction of breast CSC independent of inhibition of cholesterol biosynthesis and of protein farnesylation. Further modulation of this metabolic pathway demonstrated that protein geranylgeranylation (GG) is critical to breast CSC maintenance. A small molecule inhibitor of the geranylgeranyl transferase I (GGTI) enzyme reduced the breast CSC subpopulation both in vitro and in primary breast cancer xenografts. We found that the GGTI effect on the CSC subpopulation is mediated by inactivation of Ras homolog family member A (RHOA) and increased accumulation of P27(kip1) in the nucleus. The identification of protein GG as a major contributor to CSC maintenance opens promising perspectives for CSC targeted therapy in basal breast cancer.     

Normal breast stem cells, malignant breast stem cells, and the perinatal origin of breast cancer

Both experimental and epidemiological evidence support the concept that the in utero environment can influence an individual's risk of breast cancer in adult life. Recently identified breast stem cells may be the key to understanding the mechanism underlying this phenomenon. It has been theorized that breast cancers arise from breast stem cells. Our emerging view of the characteristics of normal breast stem cells and their link to malignant breast stem cells is reviewed here. It has also been postulated that factors that expand the normal breast stem cell pool in utero would increase the probability that one such cell might undergo an oncogenic mutation or epigenetic change. We dicuss how a number of proposed perinatal determinants of adult breast cancer risk, including (1) in utero estrogen and IGF-1 levels, (2) birthweight, (3) breast density, and (4) early-life mutagen exposure, can be tied together by this “breast stem cell burden” hypothesis.     

上皮-间质转化与乳腺癌干细胞

乳腺癌干细胞是导致乳腺癌复发、转移和耐药的根源之一。上皮间质转化(epithelial-mesenchymal transition,EMT)不仅赋予乳腺癌细胞迁移和侵袭特征,还可使癌细胞获得自我更新能力而具有干细胞的特性,从而促进乳腺癌干细胞的产生。EMT可以作为乳腺癌干细胞研究的一个新的切入点。本文就近年来该方面的研究进展做简要综述。     

The role of tumor-associated macrophages in the development,metastasis and treatment of breast cancer

Tumor-associated macrophages (TAMs) play an important role in promoting cancer in the breast cancer microenvironment. A large number of preclinical studies have demonstrated that TAMs regulate related signaling pathways by releasing a variety of chemokines, affecting breast cancer growth, metastasis, and drug resistance. In recent years, TAMs have attracted much attention as potential biomarkers for breast cancer. This article reviews the preclinical evidence of the relationship between TAMs and the breast cancer microenvironment, the role of TAMs in prognosis, and the clinical outcomes related to targeted therapy.     

The molecular pathology of hereditary breast cancer: genetic testing and therapeutic implications.

Cancer arising in carriers of mutations in the BRCA1 and BRCA2 genes differs from sporadic breast cancer of age-matched controls and from non-BRCA1/2 familial breast carcinomas in its morphological, immunophenotypic and molecular characteristics. Most BRCA1 carcinomas have the basal cell phenotype, a subtype of high-grade, highly proliferating, estrogen receptor- and HER2-negative breast carcinomas, characterized by the expression of basal or myoepithelial markers such as basal keratins, P-cadherin, epidermal growth factor receptor, etc. This phenotype is rarely found in BRCA2 carcinomas, which are of higher grade than sporadic age-matched controls, but tend to be estrogen receptor- and progesterone receptor-positive. The expression of the cell-cycle proteins cyclins A, B1 and E and SKP2 is associated with a BRCA1 phenotype, whereas cyclin D1 and p27 expression is associated with BRCA2 carcinomas. Recent studies have shown that hereditary carcinomas that are not attributable to BRCA1/2 mutations have phenotypic similarities to BRCA2 tumors, but tend to be of lower grade and proliferation index. Somatic mutations in the BRCA genes are rarely found in hereditary tumors; by contrast, BRCA1 and BRCA2 loss of heterozygosity (LOH) is found in almost all BRCA1 and BRCA2 carcinomas, respectively. Furthermore, all types of hereditary breast carcinomas have a low frequency of HER2 expression. Finally, comparative genomic hybridization studies have revealed differences in chromosomal gains and losses between genotypes. The pathological and molecular features of hereditary breast cancer can drive specific treatments and influence the process of mutation screening. In addition, detecting molecular changes such as BRCA1/2 LOH in nonatypical cells obtained by random fine-needle aspiration, ductal lavage or nipple aspirate fluid may help to earlier identify carrier women who are at an even higher risk of developing breast carcinoma.     

Bone metastasis: pathogenesis and therapeutic implications

Advanced cancers are prone to metastasize. Visceral metastases are more likely to be fatal, while patients with only metastases to bone can survive up to 10 years or more. However, effective treatments for bone metastases are not yet available and bisphosphonates improve the quality of life with no life-prolonging benefits. Bone metastases are classified as osteolytic, osteosclerotic or mixed lesions according to the bone cell types more prominently involved. Either conditions induce high morbidity and dramatically increase the risk of pathological fractures. Several molecular mechanisms bring about cancer cells to metastasize to bone, and osteotropic cancer cells are believed to acquire bone cell-like properties which improve homing, adhesion, proliferation and survival in the bone microenvironment. The acquisition of a bone cell pseudo-phenotype, denominated osteomimicry, is likely to rely on expression of osteoblastic and osteoclastic genes, thus requiring a multigenic programme. Several microenvironmental factors improve the ability of cancer cells to develop at skeletal sites, and a reciprocal deleterious stimulation generates a vicious cycle between the tumour cells and the cells residing in the bone environment. The impact of the stem cell niche in the development of bone metastases and in the phenomenon of tumour dormancy, that allows tumour cells to remain quiescent for decades before establishing overt lesions, is at present only speculative. However, the osteoblast niche, known to maintain the haematopoietic stem cell population in a quiescent status, is likely to be involved in the development of bone metastases and this promising research field is rapidly expanding.     

The Measure of DAMPs and a role for S100A8 in recruiting suppressor cells in breast cancer lung metastasis

To determine whether there was a relationship between damage associated molecular pattern molecule (DAMP) expression and recruitment of suppressor cells to sites of metastasis we measured relative expression of DAMPs, regulatory T cells (Tregs), and myeloid derived suppressor cells (MDSC) in mice at various stages of breast cancer progression using the 4T1 model. Although S100A8 was expressed at relatively low levels in the tumor cells, expression was 100-fold higher in the lung and liver which are common sites of metastasis for this tumor. Despite the relatively high level of S100A8 expression in the lungs of naïve mice, the level of expression increased further and was significantly elevated after only 7 days of tumor growth. The same pattern was observed for MDSC, and both S100A8 and MDSC expression peaked in the lungs of mice following 21 days of tumor growth. Characterization of MDSC from the lungs revealed expression of RAGE, and the cells were capable of migrating in a dose-dependent manner toward S100A8. In addition, the MDSC expressed low levels of MHC Class I, MHC Class II, CD80, and secreted TGF-β. Taken together, these data suggest that expression of S100A8 in the lungs may facilitate recruitment of MDSC, which may in turn aid in establishing a metastatic niche capable of suppressing a localized immune response.     

乳腺原发癌和淋巴结转移癌干细胞Hedgehog信号通路相关基因的比较

目的:探讨Hedgehog信号通路相关基因在乳腺原发癌干细胞与其相应的淋巴结转移癌干细胞中的表达及意义。方法:收集新鲜的乳腺癌标本,经快速病理诊断为乳腺浸润性导管癌,且伴有腋窝淋巴结的转移,采用免疫磁珠分选法分别提取乳腺原发癌与淋巴结转移癌干细胞,采用Real-time PCR检测Hedgehog信号通路相关基因Shh、Ptch、Smo和Gli-1在乳腺原发癌干细胞与相应转移癌干细胞中的表达。结果:Shh在乳腺原发癌干细胞和相应淋巴结转移癌干细胞中的表达没有统计学意义;Ptch在乳腺原发癌干细胞的表达明显高于转移癌干细胞,而Smo、Gli-1在乳腺原发癌干细胞的表达明显低于转移癌干细胞。结论:与乳腺原发癌干细胞相比,转移癌干细胞Hedgehog信号通路处于更高的活化状态,从而具有更强的侵袭和转移能力,有可能成为新的治疗靶点。     

胃癌干细胞CSC-G在胃癌侵袭和转移中的作用

BACKGROUND: Studies have shown that cancer stem cells play an important role in tumor invasion and metastasis, but studies on the role of gastric cancer stem cells in invasion and metastasis of gastric cancer cells were rarely reported. OBJECTIVE: To study the effect of gastric cancer stem cells CSC-G on invasion and metastasis of gastric cancer cells. METHODS: Gastric cancer stem cells CSC-G and gastric cancer cells SGC7901 were cultured in vitro for 10 days followed by spherical colony formation assay, western blot assay for detecting OCT4, SOX2, E-cadherin and CD44 protein expression levels in gastric cancer stem cells CSC-G and gastric cancer cells SGC7901, and Transwell assay for detecting the invasion and migration of gastric cancer stem cells and gastric cancer cells SGC7901. RESULTS AND CONCLUSION: Gastric cancer cells SGC7901 in RPMI1640 medium presented with adherent growth and were quadrilateral or polygonal after passage; gastric cancer stem cells CSC-G in serum-free medium presented with suspension growth, and adherent gastric cancer stem cells were spindle-shaped or round. Compared with gastric cancer cells SGC7901, the protein expressions of OCT4, SOX2 and CD44, the number of cancer cell spheres and the number of trans-membrane cells were significantly increased in the gastric cancer stem cells CSC-G (P < 0.05), and the expression of E-cadherin protein was significantly decreased (P < 0.05). These findings indicate that the gastric cancer stem cells CSC-G can be successfully cultured in vitro, and have enhanced invasion and migration compared with the gastric cancer cells SGC7901, which play an important role in gastric cancer invasion and metastasis.      

The role of EphB4 and IGF-IR expression in breast cancer cells

Objective: to investigate the role of EphB4 and IGF-1R in the proliferation and migration of breast cancer. Methods: The relative mRNA levels of EphB4 were measured by RT-PCR. The proliferation of the cells was determined by MTT assay, and cells migration and invasive ability was analyzed using the scratch migration assay. Results: The expression of EphB4 in control group was significantly decreased when compared with IGF-I group (P < 0.001). The expression of EphB4 in IGF-I+LY and LY group were lower than that of the control group (P < 0.001).The cell proliferation and migration ability of the cells in IGF-I group increased significantly compared to the cells in the control group (P < 0.001), while the cells in IGF-1+LY group and LY group showed a decreased proliferation and migration ability compared to the control group (P < 0.001). Conclusion: IGF-IR might be a upstream gene of EphB4. Besides, higher expression of EphB4 shows increased tumor proliferation and migration in breast cells. The study of EphB4 upstream gene and signaling pathway can provide more targeted anti-tumor point selection for targeted therapy.     

ZNF259促进乳腺癌细胞的侵袭和迁移能力

目的锌指蛋白259(ZNF259)可以结合表皮生长因子受体细胞内的酪氨酸激酶功能域,但其在肿瘤细胞中的生物学功能尚不明确。本研究拟探索其对人乳腺癌细胞生物学行为的调控。方法通过ZNF259特异性小RNA干扰实现在人乳腺癌细胞系中下调ZNF259的蛋白表达水平,利用此细胞模型通过基质胶侵袭和划痕实验来揭示ZNF259对肿瘤细胞的侵袭和转移的调控作用。结果在乳腺癌细胞系中ZNF259表达显著高于其在人正常乳腺上皮细胞系的表达。在乳腺癌细胞系MCF-7和MDA-MB-231中特异性干扰ZNF259的表达可显著抑制肿瘤细胞的侵袭和转移能力。结论 ZNF259促进乳腺癌细胞的侵袭和迁移,参与乳腺癌的发生和发展。     

Trafficking of normal stem cells and metastasis of cancer stem cells involve similar mechanisms: pivotal role of the SDF-1-CXCR4 axis

The alpha-chemokine stromal-derived factor (SDF)-1 and the G-protein-coupled seven-span transmembrane receptor CXCR4 axis regulates the trafficking of various cell types. In this review, we present the concept that the SDF-1-CXCR4 axis is a master regulator of trafficking of both normal and cancer stem cells. Supporting this is growing evidence that SDF-1 plays a pivotal role in the regulation of trafficking of normal hematopoietic stem cells (HSCs) and their homing/retention in bone marrow. Moreover, functional CXCR4 is also expressed on nonhematopoietic tissue-committed stem/progenitor cells (TCSCs); hence, the SDF-1-CXCR4 axis emerges as a pivotal regulator of trafficking of various types of stem cells in the body. Furthermore, because most if not all malignancies originate in the stem/progenitor cell compartment, cancer stem cells also express CXCR4 on their surface and, as a result, the SDF-1-CXCR4 axis is also involved in directing their trafficking/metastasis to organs that highly express SDF-1 (e.g., lymph nodes, lungs, liver, and bones). Hence, we postulate that the metastasis of cancer stem cells and trafficking of normal stem cells involve similar mechanisms, and we discuss here the common molecular mechanisms involved in these processes. Finally, the responsiveness of CXCR4+ normal and malignant stem cells to an SDF-1 gradient may be regulated positively/primed by several small molecules related to inflammation which enhance incorporation of CXCR4 into membrane lipid rafts, or may be inhibited/blocked by small CXCR4 antagonist peptides. Consequently, strategies aimed at modulating the SDF-1-CXCR4 axis could have important clinical applications both in regenerative medicine to deliver normal stem cells to the tissues/organs and in clinical hematology/oncology to inhibit metastasis of cancer stem cells.     

间充质干细胞移植治疗心血管疾病的应用与进展

背景：间充质干细胞因其具有自我更新、向不同组织分化及免疫调节功能,而被作为治疗急性心肌梗死、心力衰竭等心血管疾病的有效的方法之一。 目的：从间充质干细胞的生物特性,转分化能力、免疫调节、心脏修复的作用机制以及间充质干细胞用于治疗心血管疾病早期的临床实验资料做一简要阐述。 方法：以“间充质干细胞、免疫调控、心肌梗死、心力衰竭”,“MSCs,Immunomodulation,myocardial infarction,heart  failure”为检索词,应用计算机检索维普(VIP)期刊全文数据库及Pubmed 数据库。排除与研究目的无关和内容重复者。保留35篇文献做进一步分析。 结果与结论：间充质干细胞作为理想的种子细胞,除了具备自我更新、多向分化潜能之外,还具有免疫调节功能,避免同种异体移植或异种移植引起的免疫排斥反应。它可以向心肌细胞及脉管系统分化,通过旁分泌作用分泌一系列的细胞活素类物质及生长因子,并且动员内在的心肌干细胞,从而起到改善心功能,诱导逆向重塑,降低心梗面积的作用。相关的临床实验也显示了移植间充质干细胞的可行性和有效性。     

RANK expression on breast cancer cells promotes skeletal metastasis

RANK ligand (RANKL), acting through its cognate receptor RANK, is a key factor for bone remodeling and metastasis by regulating the differentiation, survival and activation of osteoclasts. RANKL is also crucial for the development of mouse mammary glands during pregnancy and has been recently linked to the etiology of breast cancer via its direct activity on RANK-expressing normal or transformed breast epithelial cells, leading to increased mitogenesis, enhanced regenerative potential of mammary stem cells, and increased invasion and migration. We demonstrate that higher RANK expression in MDA-MB-231 breast cancer cells (MDA-231-RANK cells) is sufficient to confer a significantly greater metastatic growth rate in the bone compared with MDA-MB-231 cells which do not express high levels of RANK. Blockade of osteoclastic bone resorption, achieved with treatment by either RANKL inhibition or zoledronic acid, did reduce skeletal tumor progression of MDA-231-RANK cells suggesting that the vicious cycle contributes to metastatic growth. However, RANKL inhibition reduced skeletal growth of MDA-231-RANK tumors to a significantly greater extent than zoledronic acid, indicating that skeletal growth of RANK-positive tumors is also driven by direct RANKL effects. RANKL stimulated the expression of multiple genes associated with cell invasive behavior, including several matrix metalloproteinases and other genes previously defined as part of a bone metastasis gene signature. These data indicate that RANKL provokes breast cancer bone metastases via two distinct, but potentially overlapping mechanisms: stimulation of tumor-associated osteoclastogenesis and stimulation of RANK-expressing tumor cells.     

The role of tumor-associated macrophages in breast carcinoma invasion and metastasis

The main purpose of this study was to investigate the infiltration of tumor-associated macrophages (TAMs) in normal and malignant breast tissue and the draining lymph nodes, and to explore its effect on breast cancer invasion and metastasis. The infiltration densities of TAMs was observed using immunohistochemical staining of CD68 in 100 cases of breast cancer specimens and its paired adjacent non-cancer breast tissues and draining lymph modes, and then to evaluate the relation of TAMs to various clinicopathological features including patients prognosis in breast carcinoma. We observed the infiltration densities of TAMs were significantly higher in breast carcinoma tissue than in adjacent normal tissue and significantly higher in much larger size and higher stage cases. Furthermore, infiltration densities of TAMs have negative correlation with the 5-year survival rates of breast cancer patients. But in matched lymph-nodes, the infiltration densities of TAMs were significantly lower in cancerous metastatic lymph-node samples than in non-metastatic one. Therefore, our data suggests that TAMs infiltration in primary tumor promote invasion and lymphatic metastasis of breast cancer and have negative correlation with patients prognosis in breast cancer, but in lymph-node TAMs may play another role and need further study in the future.     

胃癌干细胞在胃癌侵袭、转移中及血管形成中的作用和机制

BACKGROUND: Although tumor stem cells and their differentiated vascular cells, which are not sensitive to chemotherapy and molecular targeted therapy, reduce overall blood supply of the tumor, these cells facilitate the invasion and metastasis of the tumor, eventually resulting in treatment failure.     

乳腺原发癌和相应淋巴结转移癌干细胞Wnt、Notch信号通路相关分子的比较

目的：探讨乳腺原发癌和相应淋巴结转移癌干细胞Wnt、Notch信号通路分子β-catenin、Cyclin D1和Notch1 mRNA表达及意义。方法选取乳腺浸润性导管癌30例,且均伴有淋巴结转移,制备乳腺癌单细胞悬液,通过免疫磁珠分选技术分别提取乳腺原发癌和相应淋巴结转移癌干细胞,采用实时荧光定量PCR技术检测两种癌干细胞Wnt、Notch信号通路关键分子β-catenin、Cyclin D1和Notch1 mRNA的表达。结果乳腺原发癌干细胞和相应淋巴结转移癌干细胞中β-catenin mRNA的表达差异无统计学意义(P>0.05);淋巴结转移癌干细胞中Cyclin D1和Notch1 mRNA的表达显著高于乳腺原发癌干细胞(P<0.01)。结论与乳腺原发癌干细胞相比,淋巴结转移癌干细胞中Cyclin D1和Notch1处于更高的活化状态,具有更高的侵袭和转移能力,有可能成为乳腺癌的新治疗靶点。     

干细胞与肿瘤发生的关系

Stem ceils are a lineage with capacities of self- renewal and multipotential differentiation.They are exactly regulated by microenvironment where they live. With the understanding of stem ceils biology,researchers noticed that stem ceils have many similar biology characters with tumor cells, and thought that tu-mors were likely derived from stem ceils, and gave a concept that there were tumor stem ceils in tumor tissues.