MicroRNA-101 inhibits angiogenesis via COX-2 in endometrial carcinoma

Abnormal angiogenesis is critically involved in tumor progression and metastasis including endometrial cancer and is regulated by microRNAs such as microRNA-101 (miR-101). We hypothesize that miR-101 expression is disrupted in endometrial cancer and modulation of miR-101 levels is sufficient to regulate tumor growth through angiogenesis. We examined the expression levels of miR-101 and factors involved in angiogenesis in the patients with endometrial cancer. We also overexpressed or inhibited miR-101 in RL-95-2 cells and examined their effects on cell toxicity and tumor growth. Finally, we determined if miR-101 regulated tumorigenesis through cyclooxygenase-2 (COX-2). We found that miR-101 levels were significantly reduced. Factors involved in angiogenesis included vascular endothelial growth factor-A (VEGF-A), thrombospondin-1 (TSP-1), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and aromatase (P450arom), which were increased in endometrial carcinoma. Modulation of miR-101 level was sufficient to affect tumor growth. Finally, we found that the effects of miR-101 inhibition on tumor growth were suppressed by COX-2 inhibition. Our results suggest that modulating miR-101 and COX-2 levels or their activity may be a potential therapeutic strategy for endometrial cancer.     

耐三苯氧胺乳腺癌异种移植瘤动物模型建立与评价

目的：建立耐三苯氧胺（TAM）人乳腺癌的裸鼠移植瘤模型,为研究和治疗乳腺癌对TAM耐药提供研究工具。方法：采用雌激素受体阳性,对TAM耐药的人乳腺癌细胞系LCC2,接种于BALB/c裸鼠皮下,观察肿瘤生长趋势,用免疫组化方法进行鉴定。结果：在接种细胞数大于5×106/只时,Matrigel能够显著促进移植瘤的生长。肿瘤组织病理学检测证实为浸润性导管癌,且Pgp和Her-2为阳性表达。结论：该方法建立的耐TAM人乳腺癌移植瘤模型,周期短,成瘤率高,保留了与细胞系相同的肿瘤生物学特征。     

Human endometrial epithelial cell lines for studying steroid and cytokine actions

Summary Recent studies suggest that the proliferation and expression of HLA-DR molecules in endometrial epithelium may be regulated by systemic steroids and local cytokines. To test the interacting influences of cytokines and steroids on the expression of HLA-DR and proliferation of epithelial cells, an endometrial cell model is required that is sensitive to both signals. In this study, we characterize cells of carcinoma cell lines of endometrial lineage for their responsiveness to cytokines and steroids. Independently developed for its response to steroid hormones from a well-differentiated adenocarcinoma of human endometrium, EnCa101AE cell line is further cloned for the expression of progesterone receptor. Immunohistochemical localization using monoclonal antibodies demonstrates that both EnCa101AE cell line and cloned ECC1 cells are purely epithelial, as evidenced by the expression of cytokeratin and epithelial membrane antigen, express estrogen receptors, and concomitantly exhibit IFN-gamma receptor. Experiments using radioiodinated IL-1 reveal that these cell lines also possess high affinity receptors for IL-1. As indicated by the induction of HLA-DR molecules, and alterations in morphologic characteristics, these cell lines are sensitive to both IFN-gamma and IL-1 action. The class II molecules (HLA-DR, HLA-DP, and HLA-DQ) are differentially induced by IFN-gamma treatment in carcinoma cell lines, with HLA-DR being the prevailing induced molecule. IFN-gamma inhibits and estradiol-17β promotes growth of ECC1 cells in a dose-and time-dependent manner. These findings indicate that the interacting effect(s) of the cytokines and steroid hormones on endometrial epithelium may be studied in these unique steroid-and cytokine-sensitive epithelial cell lines.     

Comparing the effects of atamestane, toremifene and tamoxifen alone and in combination, on bone, serum lipids and uterus in ovariectomized rats

Complete estrogen blockade remains under investigation as a means to optimize anti-estrogen therapy in breast cancer thus both the efficacy and end-organ toxicities are of interest with combinations. We hypothesized that a steroidal aromatase inhibitor (AI) atamestane (ATA) alone, and in combination with the anti-estrogens tamoxifen (TAM) or toremifene (TOR) would have beneficial effects in ovariectomized (OVX) rats on key end-organ functions including bone and lipid metabolism and on the endometrium. Significant positive effects on bone were noted with ATA, TOR, TAM, ATA + TOR, or ATA + TAM. TOR, TAM, ATA + TOR, or ATA + TAM caused significant decreases in serum cholesterol and low-density lipoprotein cholesterol whereas ATA had no effect. Uterine weight and epithelium lining height were not increased by ATA but were by TOR and TAM. No significant differences were found in the key parameters outlined above between OVX rats given TOR and ATA + TOR, or TAM and ATA + TAM. Our data show that ATA in combination with TOR or TAM is equivalent to TOR or TAM alone in terms of end-organ effects within a range of clinically relevant doses. Further studies of combinations of AIs with anti-estrogens on end-organ function are merited.     

耐三苯氧胺乳腺癌异种移植瘤动物模型建立与评价

目的:建立耐三苯氧胺(TAM)人乳腺癌的裸鼠移植瘤模型,为研究和治疗乳腺癌对TAM耐药提供研究工具。方法:采用雌激素受体阳性,对TAM耐药的人乳腺癌细胞系LCC2,接种于BALB/c裸鼠皮下,观察肿瘤生长趋势,用免疫组化方法进行鉴定。结果:在接种细胞数大于5×106/只时,Matrigel能够显著促进移植瘤的生长。肿瘤组织病理学检测证实为浸润性导管癌,且Pgp和Her-2为阳性表达。结论:该方法建立的耐TAM人乳腺癌移植瘤模型,周期短,成瘤率高,保留了与细胞系相同的肿瘤生物学特征。     

Toremifene and tamoxifen have similar efficacy in the treatment of patients with breast cancer: a meta-analysis of randomized trials

A meta-analysis of randomized trials was performed to compare the efficacy of toremifene (TOR) with tamoxifen (TAM) in patients with breast cancer. A total of 4,768 intention-to-treat patients from nine randomized trials were identified, with 2,587 patients in TOR group and 2,181 patients in TAM group. The primary outcomes were objective response rate (ORR), time to progression (TTP), and overall survival (OS). The ORR for TOR group was 26.2 % (303/1,156), whereas the ORR for TAM group was 25.2 % (284/1,128). The pooled RR suggested that the ORR were not statistically different between the two therapeutic groups (RR 1.04, 95 % CI 0.91–1.20, P = 0.57). The median TTP was 6.7 months for the TOR group and 9.7 months for the TAM group. The median OS was 30.1 months for the TOR group and 31.7 months for the TAM group. There were no significant difference in TTP and OS between two therapeutic groups (for TTP: HR 0.91, 95 % CI 0.82–1.00; for OS: HR 1.02, 95 % CI 0.91–1.15). Adverse events were generally similar in two therapeutic groups, but TOR may cause fewer vaginal bleeding (4.0 vs. 6.7 %, P < 0.01), headache (0.2 vs. 3.1 %, P = 0.02) and thromboembolic events (4.7 vs. 7.0 %, P = 0.04). Sensitivity analyses were performed by deleting a single study each time; all the results were not materially altered. In summary, the results of this meta-analysis suggest that TOR and TAM have similar efficacy in the treatment of patients with breast cancer.     

Cytotoxicity of tamoxifen in normal and tumoral cell lines and its ability to induce cellular transformation in vitro

Tamoxifen (TAM) is a non-steroidal anti-estrogen used to treat patients with estrogen receptor-positive breast cancer and as a chemopreventive agent against breast cancer in high risk pre- and post-menopausal women. However, recent studies have shown that tamoxifen causes endometrial and hepatic cancer. In this study, we examined the effects of tamoxifen (5, 10, 25 and 50 microM) on the growth and proliferation of nine tumoral cell lines (UACC62, MCF-7, NCI-460, K-562, OVCAR-03, PC-03, HT-29, 786-0, NCI-ADR) and non-tumoral cell lines (3T3, V79, MDCK, VERO). Chinese hamster lung fibroblasts (V79) were the most sensitive lineage to tamoxifen, with 21.6% of the cells showing apoptosis at 50 microM TAM. Microscopic analysis showed that, the cellular transformation caused by TAM in V79 cells was similar to that seen with 7,12-dimethylbenz(a)anthracene, thus indicating the carcinogenicity of TAM.     

Defective expression of the monocyte chemotactic protein-1 receptor CCR2 in macrophages associated with human ovarian carcinoma

Monocyte chemotactic protein-1 (MCP-1, CCL2) is an important determinant of macrophage infiltration in tumors, ovarian carcinoma in particular. MCP-1 binds the chemokine receptor CCR2. Recent results indicate that proinflammatory and anti-inflammatory signals regulate chemokine receptor expression in monocytes. The present study was designed to investigate the expression of CCR2 in tumor-associated macrophages (TAM) from ovarian cancer patients. TAM isolated from ascitic or solid ovarian carcinoma displayed defective CCR2 mRNA (Northern blot and PCR) and surface expression and did not migrate in response to MCP-1. The defect was selective for CCR2 in that CCR1 and CCR5 were expressed normally in TAM. CCR2 gene expression and chemotactic response to MCP-1 were decreased to a lesser extent in blood monocytes from cancer patients. CCR2 mRNA levels and the chemotactic response to MCP-1 were drastically reduced in fresh monocytes cultured in the presence of tumor ascites from cancer patients. Ab against TNF-alpha restored the CCR2 mRNA level in monocytes cultured in the presence of ascitic fluid. The finding of defective CCR2 expression in TAM, largely dependent on local TNF production, is consistent with previous in vitro data on down-regulation of chemokine receptors by proinflammatory molecules. Receptor inhibition may serve as a mechanism to arrest and retain recruited macrophages and to prevent chemokine scavenging by mononuclear phagocytes at sites of inflammation and tumor growth. In the presence of advanced tumors or chronic inflammation, systemic down-regulation of receptor expression by proinflammatory molecules leaking in the systemic circulation may account for defective chemotaxis and a defective capacity to mount inflammatory responses associated with advanced neoplasia.     

Immune-deficient animals to study "hormone-dependent" breast and endometrial cancer

Athymic (nu/nu) mice are T cell deficient and can accept xenografts of human tumor material. Hormone-dependent tumor growth can be demonstrated in ovariectomized athymic mice by estrogen administration. Estrogen receptor (ER) positive MCF-7 breast cancer cells implanted into the axillary mammary fat do not grow into palpable tumors unless sustained release preparations of estrogen are administered. The non-steroidal antiestrogen tamoxifen, though it exhibits estrogenic properties in the mouse, does not facilitate MCF-7 tumor growth (during short term, i.e. 8 weeks of therapy) and can prevent estradiol-stimulated growth. In contrast, ER negative MDA-MB-231 cells grow with or without estrogen administration and tamoxifen does not control tumor growth. These statements reflect current dogma concerning the value of athymic mice to confirm the hormone dependent growth of cancer cells in vivo. Our aim has been to define the limits of this dogma and to investigate the growth relationship of hormone-dependent and independent cells with their host environment. The potential endocrine or paracine effect of ER negative tumors on the growth of ER positive tumors was evaluated by transplantation on opposite sides of athymic mice or by the inoculation of different ratios of ER positive/negative cells (MCF-7:MDA-MB-231 9:1, 99:1, 999:1). MCF-7 cells could not be encouraged to grow by a rapidly growing MDA-MB-231 tumor on the opposite side of the animal. Similarly ER negative tumors grew out of the mixed tumor inoculates suggesting that ER positive tumors could not be encouraged to grow preferentially by the paracrine influences of ER negative cells. However, estrogen facilitates the growth of an ER positive tumor following inoculation of mixed cell populations. Antiestrogen treatment can blunt estrogen-stimulated growth but cannot control the growth of ER positive/negative containing tumors. ER positive endometrial tumors grow in response to estrogen treatment and some (EnCa101) have been shown to grow in response to tamoxifen or a combination of tamoxifen and estrogen. More unusual though is our recent observation that an ER negative primary endometrial tumor (BR) and its metastasis (BR-MET) grow more rapidly in estrogen-treated athymic mice. This finding seems to have far-ranging consequences for our view of hormone-dependent growth. Either our view of estrogen-stimulated growth needs to be modified or the host is specifically altered during estrogen treatment. We have taken the position that since natural killer cells (present in athymic mice) can be lowered by estrogen this may result in an increased tumor cell survival in the heterotransplant model.(ABSTRACT TRUNCATED AT 400 WORDS)     

Interaction of sesame seed and tamoxifen on tumor growth and bone health in athymic mice

Some premenopausal breast cancer patients use phytoestrogen-rich soy and flaxseed to alleviate side effects induced by drugs such as tamoxifen (TAM). Lignan-rich flaxseed protects against breast cancer and increases the effectiveness of TAM. This study determined the interactive effects of lignan-rich sesame seed (SS) and TAM on estrogen-responsive MCF-7 breast tumor growth and bone health in ovariectomized athymic mice under premenopausal-simulated conditions. Ovariectomized mice with an estrogen implant and established MCF-7 tumors were treated for 8 weeks as follows: (i) positive control fed basal diet (BD), (ii) SS group fed BD supplemented with 10% ground SS, (iii) TAM group with TAM implant fed BD, (iv) SS + TAM group with TAM implant fed BD supplemented with 10% SS, and (v) negative control fed BD with no estrogen implant. Palpable tumor data, adjusted for body weight, showed that SS does not inhibit MCF-7 tumor growth and tends to negate the tumor inhibitory effect of TAM by increasing cell proliferation and reducing apoptosis. SS alone and combined with TAM enhanced femur biomechanical strength but caused no differences in bone mineral content or bone mineral density in either the femur or lumbar vertebrae. SS is not protective and interacts adversely with TAM in MCF-7 breast tumors but induces beneficial effects on bone both alone and when combined with TAM.     

4-Hydroxytamoxifen sulfation metabolism

Tamoxifen (TAM) is an important chemotherapeutic agent for the treatment of breast cancer. It has also been shown to decrease breast cancer incidence in healthy women at high risk for the disease. The increased risk of endometrial cancer in women has raised concerns in the use of the drug. Tamoxifen has also been shown to be a potent hepatocarcinogen in rats. The oxidative metabolites of TAM include alpha-hydroxytamoxifen (alpha-OH-TAM) and 4-hydroxytamoxifen (4-OH-TAM). The studies on the sulfation of these metabolites are very limited. It has been reported that alpha-OH-TAM is a substrate for rat hydroxysteroid sulfotransferase a (STa). Our studies on the sulfation of 4-OH-TAM demonstrated that 4-hydroxytamoxifen can be sulfated by human liver and human intestinal cytosols. Human phenol-sulfating sulfotransferase and human estrogen sulfotransferase are the major enzymes for the sulfation of 4-OH-TAM. Human dopamine-sulfating sulfotransferase also has sulfation activity for 4-OH-TAM. In contrast, rat liver and intestine cytosols have no detectable sulfation activity for 4-OH-TAM. The results suggest that the alpha-OH-TAM sulfation pathway leads to bioactivation of TAM, and the 4-OH-TAM sulfation pathway leads to detoxification of TAM. This agrees with the fact that TAM is more toxic for rats than for human beings.     

The G protein-coupled receptor GPR30 mediates the proliferative and invasive effects induced by hydroxytamoxifen in endometrial cancer cells

The selective ER modulator tamoxifen (TAM(1)) is the most widely used ER antagonist for treatment of women with hormone-dependent breast tumor. However, long-term treatment is associated with an increased risk of endometrial cancer. The aim of the present study was to demonstrate new insight into the role of G-protein coupled receptor 30 (GPR30) in the activity of TAM, which promoted endometrial cancer. In endometrial cancer cell lines ISHIKAWA and KLE, the potential of 4-hydroxytamoxifen (OHT), the active metabolite of TAM, 17β-estradiol (E2) and G1, a non-steroidal GPR30-specific agonist to promote cell proliferation and invasion was evaluated. All agents above induced high proliferative and invasive effects, while the down-regulation of GPR30 or the interruption of MAPK signal pathway partly or completely prevented the action of the regent. Moreover, the RNA and protein expression of GPR30 was up-regulated by G1, E2 or OHT in both cell lines. The present study provided a new insight into the mechanism involved in the agonistic activity exerted by TAM in the uterus.     

HGF-induced PKCζ activation increases functional CXCR4 expression in human breast cancer cells

The chemokine receptor CXCR4 and its ligand CXCL12 have been shown to mediate the metastasis of many malignant tumors including breast carcinoma. Interaction between hepatocyte growth factor (HGF) and the Met receptor tyrosine kinase mediates development and progression of cancers. HGF is able to induce CXCR4 expression and contributes to tumor cell invasiveness in breast carcinoma. However, the mechanism of the CXCR4 expression modulated by c-Met-HGF axis to enhance the metastatic behavior of breast cancer cells is still unclear. In this study, we found that HGF induced functional CXCR4 receptor expression in breast cancer cells. The effect of HGF was specifically mediated by PKCζ activity. After transfection with PKCζ-siRNA, the phosphorylation of PKCζ and CXCR4 was abrogated in breast cancer cells. Interference with the activation of Rac1, a downstream target of HGF, prevented the HGF-induced increase in PKCζ activity and CXCR4 levels. The HGF-induced, LY294002-sensitive translocation of PKCζ from cytosol to plasma membrane indicated that HGF was capable of activating PKCζ, probably via phosphoinositide (PI) 3-kinases. HGF treatment also increased MT1-MMP secretion. Inhibition of PKCζ, Rac-1 and phosphatidylinositol 3-kinase may attenuate MT1-MMP expression in cells exposed to HGF. Functional manifestation of the effects of HGF revealed an increased ability for migration, chemotaxis and metastasis in MDA-MB-436 cells in vitro and in vivo. Our findings thus provided evidence that the process of HGF-induced functional CXCR4 expression may involve PI 3-kinase and atypical PKCζ. Moreover, HGF may promote the invasiveness and metastasis of breast tumor xenografts in BALB/c-nu mice via the PKCζ-mediated pathway, while suppression of PKCζ by RNA interference may abrogate cancer cell spreading.     

Immunohistochemical analysis of advanced human breast carcinomas reveals downregulation of protein kinase C alpha.

Forty-six advanced-stage human breast carcinoma specimens were evaluated by immunohistochemistry for PKC alpha expression and compared with 25 samples of normal adjacent breast tissue. For normal tissue, the median staining of ductal epithelia was of moderate intensity. No staining was observed for 67% of tumor specimens, and only 4% showed intensities greater than the median observed in normal tissue. Faint to moderate PKC alpha staining was observed in the stroma, inflammatory cells, and fibroblasts of tumors but was absent in normal tissue. These findings demonstrate that downregulation of PKC alpha protein occurs in epithelial cells of advanced breast tumors (p<0.001).     

Phospholipase C-protein kinase C mediated phospholipase D activation pathway is involved in tamoxifen induced apoptosis

Tamoxifen (TAM) is the endocrine therapeutic agent the most widely used in the treatment of breast cancer, and it operates primarily through the induction of apoptosis. In this study, we attempted to elucidate the non-ER mediated mechanism behind TAM treatment, involving the phospholipase C-protein kinase C (PLC-PKC) mediated phospholipase D (PLD) activation pathway, using multimodality methods. In TAM treated MCF7 cells, the PLC and PLD protein and mRNA levels increased. Phosphatidylethanol (PEt) and diacylglycerol (DAG) generation also increased, showing increased activity of PLD and PLCgamma1. Translocation of PKCalpha, from cytosol to membrane, was observed in TAM treated cells. By showing that both PKC and PLC inhibitors could reduce the effects of TAM-induced PLD activation, we confirmed the role of PKC and PLC as upstream regulators of PLD. Finally, we demonstrated that TAM treatment reduced the viability of MCF7 cells and brought about rapid cell death. From these results, we confirmed the hypothesis that TAM induces apoptosis in breast cancer cells, and that the signal transduction pathway, involving PLD, PLC, and PKC, constitutes one of the possible mechanisms underlying the non-ER mediated effects associated with TAM.     

Site-directed perturbation of protein kinase C- integrin interaction blocks carcinoma cell chemotaxis

Polarized cell movement is an essential requisite for cancer metastasis; thus, interference with the tumor cell motility machinery would significantly modify its metastatic behavior. Protein kinase C alpha (PKC alpha) has been implicated in the promotion of a migratory cell phenotype. We report that the phorbol ester-induced cell polarization and directional motility in breast carcinoma cells is determined by a 12-amino-acid motif (amino acids 313 to 325) within the PKC alpha V3 hinge domain. This motif is also required for a direct association between PKC alpha and beta 1 integrin. Efficient binding of beta 1 integrin to PKC alpha requires the presence of both NPXY motifs (Cyto-2 and Cyto-3) in the integrin distal cytoplasmic domains. A cell-permeant inhibitor based on the PKC-binding sequence of beta 1 integrin was shown to block both PKC alpha-driven and epidermal growth factor (EGF)-induced chemotaxis. When introduced as a minigene by retroviral transduction into human breast carcinoma cells, this inhibitor caused a striking reduction in chemotaxis towards an EGF gradient. Taken together, these findings identify a direct link between PKC alpha and beta 1 integrin that is critical for directed tumor cell migration. Importantly, our findings outline a new concept as to how carcinoma cell chemotaxis is enhanced and provide a conceptual basis for interfering with tumor cell dissemination.