Akt plays an important role in breast cancer cell chemotaxis to CXCL12

The chemokine receptor CXCR4 is functionally expressed on the cell surface of various cancer cells, and plays a role in cell proliferation and migration of these cells. Specifically, in breast cancer cells the CXCR4/CXCL12 axis has been implicated in cell migration in vitro and in metastasis in vivo, but the underlying signaling mechanisms are incompletely understood. The xenograft-derived MDA-MB-231 breast cancer cell line (231mfp), which was shown previously to grow more aggressively than the parent cells, showed increased CXCR4 expression at the mRNA, total protein and cell surface expression level. This correlated with an enhanced response to CXCL12, specifically in augmented and prolonged Akt activation in a G(i), Src family kinase and PI-3 kinase dependent fashion. 231mfp cells migrated towards CXCL12-in contrast to the parent cell line-and this chemotaxis was blocked by inhibition of G(i), Src family kinases, PI-3 kinase and interestingly, Akt itself, as could be shown with two pharmacological inhibitors, a dominant negative Akt construct and with Akt shRNA. Collectively, we have demonstrated that prolonged Akt activation is an important signaling pathway for breast cancer cells expressing CXCR4 and is necessary for CXCL12-dependent cell migration.     

趋化因子CXCL12及其受体CXCR4与乳腺癌

 趋化因子CXCL12及其受体CXCR4在乳腺癌发生发展的多个过程中受到多种因素调控并表达,并且多项研究证实CXCL12及CXCR4不但有助于判断乳腺癌患者的预后,而且针对CXCR4的治疗更为乳腺癌患者提供了新的联合治疗方案,给患者更为理想的治疗。     

CXCL12/CXCR4 and breast cancer

CXCL12 and its receptor CXCR4 can express in breast cancer, and are regulated by several factors in the genesis and development of breast cancer. Lots of researches have proved that CXCL12 and CXCR4 can be used as new independent prognostic makers of breast cancer. Treatment targeted for CXCR4 can be seen as a new kind of combination therapy, which may provides patients a more ideal treatment.     

Inhibition of gap junctional intercellular communication by tumor promoters in connexin43 and connexin32-expressing liver cells: cell specificity and role of protein kinase C

In this study, we investigated whether the tumor promoters, 12-O- tetradecanoylphorbol-13-acetate (TPA), phenobarbital (PB), and 1,1- bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), inhibited gap junctional intercellular communication (GJIC) in a cell-specific or connexin-specific manner and whether protein kinase C was involved. To do this, we used highly communicating WB-F344 rat liver epithelial cells, which express connexin43 as their predominant gap junction protein, WB-aB1 cells, which are a GJIC-incompetent mutant line of WB- F344 cells and that express connexin43, WB-a/32-10 cells, which are a highly communicating derivative of WB-aB1 cells generated by stable transduction with a connexin32 retroviral expression vector, and primary cultured rat hepatocytes, which express conexin32 predominantly. Treatment of WB-F344 and WB-a/32-10 cells, but not hepatocytes, with TPA inhibited GJIC (assayed by Lucifer Yellow dye microinjection). This inhibition involved protein kinase C because (i) inhibition was prevented by co-treatment of the cells with a specific protein kinase C inhibitor, bis-indolylmaleimide, and (ii) treatment with TPA for 24 h had no effect on dye-coupling in agreement with the downregulation of protein kinase C. TPA also caused the internalization of Cx43-containing gap junctions and the formation of a hyperphosphorylated form of Cx43, Cx43-P3, in WB-F344 cells only, but TPA had no effect on Cx32-containing gap junctions or protein mobility. In contrast, PB inhibited GJIC only in hepatocytes and DDT inhibited GJIC in all three types of cells; bis-indolylmaleimide did not block the effects of either agent. These results indicate that the inhibitory actions of TPA and PB on GJIC are cell-specific rather than connexin- specific and that TPA inhibits connexin43 and connexin32-mediated GJIC through a protein kinase C-dependent mechanism.      

CXCR4和CXCL12及PTEN在乳腺癌中的表达及临床意义

 目的  分析乳腺癌、乳腺纤维腺瘤及癌旁正常乳腺组织中趋化因子受体4（CXCR4）、趋化因子12（CXCL12）与人第10号染色体缺失的磷酸酶及张力蛋白同源的基因（PTEN）的表达及临床意义。方法  采用免疫组化技术SABC法检测60例乳腺癌组织标本CXCR4、CXCL12、PTEN的表达情况,分析乳腺癌中CXCR4、CXCL12及PTEN表达与年龄、肿瘤大小、组织学分级、TNM分期、淋巴结转移、雌激素受体（ER）、人类表皮生长因子2（Her-2）及脉管侵犯的关系。另取20例乳腺纤维腺瘤及20例癌旁正常乳腺组织作为对照组。结果  免疫组化结果显示,CXCR4（χ²=48.750,P=0.000）、CXCL12（χ²=47.611,P=0.000）及PTEN（χ²=19.994,P=0.000）在乳腺癌、乳腺纤维腺瘤与癌旁正常组织中的表达差异均具有统计学意义,其中CXCR4、CXCL12阳性表达与乳腺癌的组织学分级（χ²=11.080,P=0.004;χ²=6.978,P=0.031）、TNM分期（χ²=9.819,P=0.007;χ²=10.163,P=0.006）、淋巴结转移（χ²=6.213,P=0.013;χ²=8.031,P=0.005）、ER（χ²=12.774,P=0.000;χ²=7.330,P=0.007）、脉管侵犯（χ²=5.860,P=0.013;χ²=5.185,P=0.020）及Her-2（χ²=5.487,P=0.019;χ²=4.689,P=0.030）相关;PTEN在乳腺癌组织中的表达与TNM分期（χ²=7.366,P=0.025）、淋巴结转移（χ²=5.511,P=0.019）及ER（χ²=4.077,P=0.043）状态相关。CXCR4与CXCL12在乳腺癌中的表达呈正相关（r =0.336,P=0.004）;CXCR4与PTEN、CXCL12与PTEN在乳腺癌中的表达呈负相关（r =-0.362,P=0.004;r =-0.360,P=0.004）。结论  趋化因子CXCL12及其受体CXCR4的高表达及PTEN的低表达与乳腺癌的发生和转移有关,可能在促进乳腺癌的生长和发展中起重要作用。     

洛伐他汀对 MCF-7细胞增殖分化功能及间隙连接细胞通讯的影响

背景与目的:洛伐他汀( lovastatin)是细胞内源性胆固醇合成的抑制剂,临床已普遍用于治疗高脂血症.现有研究报道,洛伐他汀具有抗肿瘤作用,但分子机制尚不清楚.本文探讨洛伐他汀对人乳腺癌细胞 MCF-7增殖功能以及间隙连接细胞通讯( gap junctional intercellular communication,GJIC)的影响.方法:分别以 4、 8、 16 μ mol/L洛伐他汀处理 MCF-7细胞 24～ 72 h后,流式细胞仪检测细胞周期的时相分布及细胞凋亡率,硝基蓝四氮唑( NBT)还原实验鉴定细胞分化,并采用划痕标记染料示踪技术观察洛伐他汀对 MCF-7细胞 GJIC功能的影响.结果:不同浓度洛伐他汀处理细胞不同时间后, MCF-7细胞的增殖明显受抑,抑制率最高可达 75.8%,且同一处理时相点各组间比较差异均有显著性 (P< 0.05);细胞周期分析显示,各处理组内 G0/G1期细胞明显增多,处理 72 h后可高达 80%左右;同时洛伐他汀能明显促进 MCF-7细胞分化、各处理组间比较差异均有显著性 (P< 0.01),但洛伐他汀诱导该细胞凋亡的作用不明显.另外,洛伐他汀有上调或恢复 MCF-7细胞 GJIC的作用; 16 μ mol/L洛伐他汀处理细胞 72 h后,荧光染料传输的范围可达 4～ 5层细胞.以上作用均有浓度-效应和时间依赖关系.结论:洛伐他汀可抑制 MCF-7细胞增殖,使细胞生长阻滞于 G0/G1期,并能促进细胞分化,该作用可能与洛伐他汀上调或恢复 MCF-7细胞的 GJIC功能有关.     

CXCL12- CXCR4在乳腺浸润性导管癌中的表达及临床意义

目的：研究乳腺浸润性导管癌中趋化因子 CXCL12及其对应的特异趋化因子受体 CXCR4的表达,分析其与浸润性导管癌临床病理学特征的关系。方法：用免疫组化法研究200例乳腺浸润性导管癌中 CX-CL12、CXCR4的表达情况,并探讨二者单一表达或共表达与临床病理因素的相关性。结果：CXCL12在40%（80/200）浸润性乳腺癌中阳性表达,其与 TNM 分期和肿瘤大小相关（P <0.05）;CXCR4在48%（96/200）浸润性乳腺癌中阳性表达,其表达与浸润性乳腺癌的 TNM 分期相关（P <0.05）。CXCL12与 CXCR4共表达于29%（58/200）的浸润性乳腺癌,二者的共表达与 TNM 分期和淋巴结转移情况相关（ P <0.01）。结论：CX-CL12与 CXCR4共表达很可能是协同乳腺浸润性导管癌进展及淋巴结转移的重要因素,检测 CXCL12与 CX-CR4共表达比检测 CXCL12或 CXCR4单一分子标记更有意义。     

Tumor associated mesenchymal stem cells protects ovarian cancer cells from hyperthermia through CXCL12

Hyperthermic intraperitoneal chemotherapy (HIPEC) has shown promise in treatment of ovarian carcinosis. Despite its efficiency for the treatment of peritoneal carcinosis from digestive tract neoplasia, it has failed to demonstrate significant benefit in ovarian cancers. It is therefore essential to understand the mechanism underlying resistance to HIPEC in ovarian cancers. Mesenchymal stem cells (MSC) play an important role in the development of ovarian cancer metastasis and resistance to treatments. A recent study suggests that MSCs may be cytotoxic for cancer cells upon heat shock. In contrast, we describe the protective role of MSC against hyperthermia. Using cytokine arrays we determined that the tumor associated MSC (TAMC) secrete pro‐tumoral cytokines. We studied the effect of hyperthermia in co‐culture setting of TAMC or BM‐MCS associated with ovarian cancer cell lines (SKOV3 and CaOV3) with polyvariate flow cytometry. We demonstrate that hyperthermia does not challenge survival of TAMC or bone marrow derived MSC (BM‐MSC). Both TAMC and BM‐MSC displayed strong protective effect inducing thermotolerance in ovarian cancer cells (OCC). Transwell experiments demonstrated the role of secreted factors. We showed that CXCL12 was inducing thermotolerance and that inhibition of CXCL12/CXCR4 interaction restored cytotoxicity of hyperthermia in co‐culture experiments. Contrary to the previous published study we demonstrated that TAMC and BM‐MSC co‐cultured with OCC induced thermotolerance in a CXCL12 dependant manner. Targeting the interaction between stromal and cancer cells through CXCL12 inhibition might restore hyperthermia sensitivity in ovarian cancers, and thus improve HIPEC efficiency.     

Breast cancer metastatic potential: correlation with increased heterotypic gap junctional intercellular communication between breast cancer cells and osteoblastic cells

The breast cancer metastasis-suppressor gene BRMS1 is downregulated in metastatic breast cancer cells. Previous reports have shown restoration of gap junctional intercellular communication (GJIC) in the metastatic human breast carcinoma cell line MDA-MB-435 (435) transfected with BRMS1 cDNA. Metastasis, to a large extent in most breast cancers, occurs to bone. However, the reason for this preferential metastasis is not known. We explored cell-to-cell communication between 435 carcinoma cells and a human osteoblastic cell line, hFOB1.19, to determine whether carcinoma cells can form gap junctions with bone cells and to explore the role of these heterotypic gap junctions and the BRMS1 gene in breast cancer metastasis to bone. 435 cells displayed greater cell-to-cell communication with hFOB 1.19 cells than with themselves. Transfection of BRMS1 into 435 cells increased homotypic gap junctional communication but did not significantly affect heterotypic communication with hFOBs. However, heterotypic communication of BRMS1 transfectants with hFOB cells was reduced relative to homotypic communication. In contrast, parental 435 cells displayed greater heterotypic communication with hFOBs relative to homotypic communication. Our results suggest that there are differences in the relative homotypic and heterotypic GJIC of metastasis-capable and -suppressed cell lines.     

Tumor-derived CXCL8 signaling augments stroma-derived CCL2-promoted proliferation and CXCL12-mediated invasion of PTEN-deficient prostate cancer cells

Impaired PTEN function is a genetic hallmark of aggressive prostate cancers (CaP) and is associated with increased CXCL8 expression and signaling. The current aim was to further characterize biological responses and mechanisms underpinning CXCL8-promoted progression of PTEN-depleted prostate cancer, focusing on characterizing the potential interplay between CXCL8 and other disease-promoting chemokines resident within the prostate tumor microenvironment. Autocrine CXCL8-stimulation (i) increased expression of CXCR1 and CXCR2 in PTEN-deficient CaP cells suggesting a self-potentiating signaling axis and (ii) induced expression of CXCR4 and CCR2 in PTEN-wild-type and PTEN-depleted CaP cells. In contrast, paracrine CXCL8 signaling induced expression and secretion of the chemokines CCL2 and CXCL12 from prostate stromal WPMY-1 fibroblasts and monocytic macrophage-like THP-1 cells. In vitro studies demonstrated functional co-operation of tumor-derived CXCL8 with stromal-derived chemokines. CXCL12-induced migration of PC3 cells and CCL2-induced proliferation of prostate cancer cells were dependent upon intrinsic CXCL8 signaling within the prostate cancer cells. For example, in co-culture experiments, CXCL12/CXCR4 signaling but not CCL2/CCR2 signaling supported fibroblast-mediated migration of PC3 cells while CXCL12/CXCR4 and CCL2/CCR2 signaling underpinned monocyte-enhanced migration of PC3 cells. Combined inhibition of both CXCL8 and CXCL12 signaling was more effective in inhibiting fibroblast-promoted cell motility while repression of CXCL8 attenuated CCL2-promoted proliferation of prostate cancer cells. We conclude that tumor-derived CXCL8 signaling from PTEN-deficient tumor cells increases the sensitivity and responsiveness of CaP cells to stromal chemokines by concurrently upregulating receptor expression in cancer cells and inducing stromal chemokine synthesis. Combined chemokine targeting may be required to inhibit their multi-faceted actions in promoting the invasion and proliferation of aggressive CaP.     

CXCL12 对人乳腺癌细胞株 MDA - MB - 435 失巢凋亡的研究

目的：研究趋化因子CXCL12对人乳腺癌高转移细胞系MDA—MB-435失巢凋亡的影响。方法：实验组培养基中加入终浓度为50ng／ml的CXCL12,对照组为无CXCLl2的DMEM培养基。两组细胞悬浮培养,建立人乳腺癌高转移细胞系MDA—MB-435失巢凋亡抵抗细胞模型。MTr检测CXCLl2对于失巢凋亡抵抗MDA—MB-435细胞系生长的影响,流式细胞仪检测两组细胞的凋亡情况,Transwe11实验检测细胞侵袭能力改变。结果：CXCLl2对于失巢凋亡抵抗MDA—MB-435细胞系在形态学方面与对照组相比无特异性改变。CXCLl2作用组失巢凋亡抵抗细胞增殖能力低于对照组,凋亡率增加,侵袭能力增加,穿过膜细胞数明显高于对照组（28±3．0VS15±2．4,P〈0．05）。结论：在人乳腺癌高转移细胞系MDA—MB-435失巢凋亡过程中,CXCL12能在一定程度上抑制失巢凋亡抵抗细胞的生长,但却能增加存活肿瘤细胞的侵袭性。     

Phosphorylation of connexin43 and inhibition of gap junctional communication in 12-O-tetradecanoylphorbol-13-acetate-exposed R6 fibroblasts: minor role of protein kinase C beta I and mu

12-O:-tetradecanoylphorbol-13-acetate (TPA) inhibits gap junctional communication in many cell culture systems, but TPA-induced phosphorylation of the gap junction protein connexin43 (Cx43) varies much between systems. We have here studied whether these responses and their sensitivities can be correlated with total protein kinase C (PKC) enzyme activity and if specific PKC isoenzymes are involved. Rat R6 fibroblasts transfected with the cDNA sequence encoding PKC beta I (R6-PKC3) had a total PKC activity 7- to 16-fold higher than the corresponding control cells (R6-C1), depending on the selection pressure (G418 concentration). Still, R6-PKC3 cells were no more sensitive than R6-C1 cells to TPA-induced down-regulation of communication, except at the highest selection pressure (500 micrograms/ml G418). Thus, total PKC activity does not indicate absolute sensitivity of a cell system to TPA-induced suppression of communication, but within a certain cell system increasing PKC activity may enhance the sensitivity to TPA in this respect. The results also suggest that PKC beta I is of minor importance for TPA-induced regulation of communication. Experiments with the Lilly compound 379196, a PKC beta-specific inhibitor, further supported this conclusion. Except for PKC beta I in R6-PKC3 cells, both cell lines contained the TPA-responsive PKC isoenzymes alpha, delta, epsilon and mu. Long-term treatment with TPA caused strong down-regulation of PKC alpha, delta and epsilon, but little down-regulation of PKC mu. Concurrently, the cells became refractory to repeated exposure to TPA, indicating that PKC mu is of minor importance. Experiments with the general PKC inhibitor GF109203X and the PKC alpha (and beta/gamma) inhibitor G?6976 suggested that both classical (alpha) and novel PKCs (delta and epsilon) might be involved in TPA-induced suppression of intercellular communication, while phosphorylation of Cx43 may mainly be mediated by PKC alpha in the present systems.     

CXCL12，CXCR4及CXCR7表达检测对乳腺癌患者疾病预后意义探讨

目的：探讨乳腺癌患者肿瘤组织中CXCL12,CXCR4和CXCR7 mRNA表达情况在肿瘤转移和疾病预后中的价值。方法采用定量PCR方法检测115例乳腺癌,临近正常组织及乳腺癌肿瘤转移患者颈部淋巴结样本中CXCL12,CXCR4和CXCR7 mRNA表达情况。随访资料采用Kaplan-Meier生存分析,对影响生存质量的因素进行多重变量Cox回归分析。结果与正常组织相比,乳腺癌组织中CXCR4和CXCR7表达明显增加,差异均有统计学意义（P﹤0.001）,两种组织中CXCL12的表达差异无统计学意义（P﹥0.05）;CXCL12在肿瘤原发部位和淋巴结转移部位的表达差异有统计学意义（P﹤0.05）,转移瘤的CXCR4和CXCR7表达均增加（P﹤0.05）。Kaplan-Meier生存分析结果表明,与CXCR4和CXCR7低表达患者相比,高表达患者的总生存率较低（P﹤0.05）。Cox回归模型显示,CXCL12、CXCR4和CXCR7表达均为影响乳腺癌患者生存情况的独立因素。结论本研究结果表明CXCL12、CXCR4和CXCR7 mRNA表达在乳腺癌患者肿瘤发展和转移中发挥重要作用,可以作为乳腺癌患者疾病预后的生物标志物。     

Inhibition of gap junctional intercellular communication and enhancement of growth in BALB/c 3t3 cells treated with connexin43 antisense oligonucleotides

Many studies have correlated reductions in gap junctional intercellular communication (a) with altered cellular growth, tumor promotion, and neoplastic transformation. To test directly whether reduced GJIC affects cellular growth, GJIC was inhibited in murine BALB/c 3T3 fibroblasts by treatment with a phosphorothioatemodified antisense oligonucleotide targeted against the connexin43 translation start codon, and in vitro cell growth was monitored. The cells were incubated with the oligonucleotide (0.1-0.5 μM) in liposomes in serumless culture medium for 16 h; washed and refed with serum-containing medium; and analyzed for dye-coupling, connexin43 protein and mRNA levels, and cell growth over the next 5 d. The antisense oligonucleotide inhibited dye-coupling and reduced connexin43 protein levels in a concentration-dependent manner but had no effect on connexin43 mRNA levels. Cell growth rate was not affected, but saturation density was increased approximately threefold by the oligonucleotide. These data support a role for GJIC in the establishment of contact inhibition of in vitro cell growth. © 1995 Wiley- Liss, Inc.     

Targeting the CXCL12/CXCR4 pathway and myeloid cells to improve radiation treatment of locally advanced cervical cancer

Cervical cancer is the fourth most commonly diagnosed cancer and the fourth leading cause of cancer death in women worldwide. Approximately half of cervical cancer patients present with locally advanced disease, for which surgery is not an option. These cases are nonetheless potentially curable with radiotherapy and cisplatin chemotherapy. Unfortunately, some tumours are resistant to treatment, and lymph node and distant recurrences are major problems in patients with advanced disease at diagnosis. New targeted treatments that can overcome treatment resistance and reduce metastases are urgently needed. The CXCL12/CXCR4 chemokine pathway is ubiquitously expressed in many normal tissues and cancers, including cervical cancer. Emerging evidence indicates that it plays a central role in cervical cancer pathogenesis, malignant progression, the development of metastases and radiation treatment response. Pre‐clinical studies of standard‐of‐care fractionated radiotherapy and concurrent weekly cisplatin plus the CXCR4 inhibitor Plerixafor (AMD3100) in patient‐derived orthotopic cervical cancer xenografts have shown improved primary tumour response and reduced lymph node metastases with no increase in early or late side effects. These studies have pointed the way forward to future clinical trials of radiotherapy/cisplatin plus Plerixafor or other newly emerging CXCL12 or CXCR4 inhibitors in women with cervical cancer.     

人参皂苷Rg3对人类乳腺癌MCF-7细胞Cx26基因表达及细胞间隙连接通讯功能的影响

目的研究人参皂苷Rg3对人类乳腺癌细胞MCF-7增殖抑制作用、连接蛋白cx26基因表达及对细胞间隙连接通讯（GJIC）功能的影响。方法使用含不同浓度人参皂苷Rg3培养基体外培养MCF-7细胞24h,并设正常培养条件下MCF-7细胞为对照组,采用四甲基偶氮唑蓝（MTF）法检测人参皂苷Rg3各浓度下MCF-7细胞增殖活力,并选取能明显抑制MCF．7细胞增殖的人参皂苷Rg3浓度组为实验组。RT—PCR检测各实验组和对照组连接蛋白Cx26 mRNA的表达。通过划痕标记荧光传输实验检测上述各组MCF,7细胞GJIC功能的恢复情况。结果在含人参皂苷Rg310、20、40、80、160斗g／ml体外培养MCF-7细胞24h后,MCF-7细胞增殖的抑制率分别为3．1％、5．2％、16．0％、26.3％、29．1％。与对照组比较,质量浓度在40μg／ml以上的人参皂苷Rg3均可明显抑制肿瘤细胞增殖（P〈0．05）,故选取含40、80、160斗g／m1人参皂苷Rg3MCF-7细胞组为实验组。在各实验组中,随人参皂苷Rg3质量浓度的增大,Cx26 mRNA表达逐渐增强,与对照组相比,差异有统计学意义（P〈0．05）。荧光黄染料划痕标记荧光传输实验显示,对照组荧光黄染料荧光染色仅限于单个细胞,各实验组荧光黄染料荧光可通过细胞间隙连接传输至相邻细胞,形成片状荧光染色。结论一定浓度人参皂苷Rg3可增强人类乳腺癌细胞MCF-7 Cx26基因表达,恢复其GJIc功能,这可能是人参皂苷Rg3抑制MCF-7细胞增殖,发挥抗肿瘤作用机制之一。     

Lipopolysaccharides increase the amount of CXCR4, and modulate the morphology and invasive activity of oral cancer cells in a CXCL12-dependent manner

Recently, it has been reported that bacterial infections play an important role in the development of cancers of the upper aero digestive tract. To examine the influence of bacterial infections on oral cancer, human oral carcinoma T3M-1 cells were treated with lipopolysaccharide (LPS) for 24 h as a model of infection. The LPS treatment increased the mRNA expression of CXCR4 and invasiveness in T3M-1 cells stimulated with CXCL12.The Rho family of small guanosine triphosphatases regulates the dynamics of the actin cytoskeleton that underlie cellular functions such as cell shape changes, migration and polarity. In T3M-1 cells treated with LPS and stimulated with CXCL12, Rac and Cdc42 were activated and caused an increase in the development of filopodia. The present findings suggest that bacterial infections enhance the invasiveness of T3M-1 cells via CXCL12/CXCR4 interaction and Cdc42-activation. Furthermore, filopodia are critical to this process.