Methylation-associated silencing of miR-9-1 promotes nasopharyngeal carcinoma progression and glycolysis via HK2

Characteristically, cancer cells metabolize glucose through aerobic glycolysis, known as the Warburg effect. Accumulating evidence suggest that during cancer formation, microRNAs (miRNAs) could regulate such metabolic reprogramming. In the present study, miR-9-1 was identified as significantly hypermethylated in nasopharyngeal carcinoma (NPC) cell lines and clinical tissues. Ectopic expression of miR-9-1 inhibited NPC cell growth and glycolytic metabolism, including reduced glycolysis, by reducing lactate production, glucose uptake, cellular glucose-6-phosphate levels, and ATP generation in vitro and tumor proliferation in vivo. HK2 (encoding hexokinase 2) was identified as a direct target of miR-9-1 using luciferase reporter assays and Western blotting. In NPC cells, hypermethylation regulates miR-9-1 expression and inhibits HK2 translation by directly targeting its 3' untranslated region. MiR-9-1 overexpression markedly reduced HK2 protein levels. Restoration of HK2 expression attenuated the inhibitory effect of miR-9-1 on NPC cell proliferation and glycolysis. Fluorescence in situ hybridization results indicated that miR-9-1 expression was an independent prognostic factor in NPC. Our findings revealed the role of the miR-9-1/HK2 axis in the metabolic reprogramming of NPC, providing a potential therapeutic strategy for NPC.     

G6PD对大肠癌细胞生长侵袭的影响及其与HKⅡ的相关性

目的 探讨G6PD对大肠癌HCT116和SW480细胞生长侵袭的影响,以及G6PD与HKⅡ在大肠癌及其癌旁上皮组织中的表达和两者的相关性。方法 将体外培养的大肠癌HCT116和SW480细胞进行G6PD过表达和干扰处理。Western blot法检测细胞中G6PD和HKⅡ的蛋白表达水平;流式细胞术分析细胞周期进程;葡萄糖氧化酶法检测培养液中葡萄糖的含量;划痕实验检测细胞侵袭能力;免疫组织化学法检测大肠癌及癌旁组织中G6PD与HKⅡ蛋白的表达水平。结果 过表达实验中,与Flag转染组相比,Flag-G6PD转染组HCT116和SW480两种细胞培养液中葡萄糖浓度、S期所占比例及侵袭能力均无明显变化;干扰实验中,与阴性对照转染组相比,G6PD-Homo-1504转染组两种细胞的葡萄糖浓度显著升高,S期所占比例和侵袭能力显著降低。G6PD与HKⅡ表达水平呈正相关。结论 干扰G6PD减少了大肠癌细胞葡萄糖的消耗,抑制了细胞的增殖和侵袭能力;同时G6PD对HKⅡ可能存在调控作用。     

PTHrP promotes colon cancer cell migration and invasion in an integrin α6β4-dependent manner through activation of Rac1

Parathyroid hormone-related protein (PTHrP) is expressed by human colon cancer tissue and cell lines. Rac1 GTPase enhances colon cancer cell migration and invasion. Here we report a positive correlation between PTHrP expression and Rac1 activity in LoVo (human colon cancer) cells. The positive effects of PTHrP on Rac1 activity and on cell migration and invasion are mediated via the guanine nucleotide exchange factor Tiam1. Knockdown of integrin α6β4, which is upregulated by PTHrP, negates the PTHrP-mediated increase in Rac1 activation. Integrin α6β4 signals synergistically with growth factor receptors to activate the phosphatidylinositol 3-kinase (PI3-K) pathway. Chemical inhibition of PI3-K negates the PTHrP-mediated effects on Tiam1 and Rac1 activity. Tumors from PTHrP-overexpressing LoVo cells also show increased expression of Tiam1. Taken together, these observations provide evidence of a link between PTHrP and Rac1 activity through integrin α6β4, resulting in enhanced cell migration and invasion. Targeting PTHrP production in colon cancer may thus prove therapeutically beneficial.     

PTTG1促进结肠癌SW480细胞侵袭和迁移的作用机制

目的 研究垂体肿瘤转化基因 1（pituitary tumor transforming gene 1, PTTG1）过表达促进人结肠癌细胞SW480侵袭和迁移作用及其可能机制。方法 采用脂质体转染法将pcDNA3.1(+)-PTTG1及空载pcDNA3.1(+)转染人结肠癌SW480细胞,G418法筛选阳性克隆。Western blot和Real-time PCR法鉴定稳定过表达PTTG1细胞株建立。Transwell小室法检测细胞侵袭和迁移能力,Western blot检测MMP2、MMP9、E-cadherin、Vimentin和Snail的表达。结果 （1）成功获得稳定高表达PTTG1的SW480克隆细胞株PTTG1-SW480;（2）过表达PTTG1基因后,SW480细胞侵袭和迁移能力增强,MMP2和MMP9表达升高,上皮间质转化（epithelial-mesenchymal transition, EMT）标记分子E-cadherin表达降低,Vimentin和Snail的表达升高,差异均有统计学意义（P<0.01）;（3）过表达PTTG1基因后,SW480细胞中PI3K/AKT信号活化增强,使用LY29400干预后,抑制细胞侵袭、迁移和EMT,E-cadherin表达上调、Vimentin和Snail的表达下调,差异均有统计学意义（P<0.01）。结论 PTTG1基因过表达可能通过活化PI3K/AKT信号诱导SW480细胞EMT发生,发挥促进SW480侵袭和迁移作用;提示PTTG1蛋白可能成为结肠癌治疗的一个潜在靶点。     

miR-30c Impedes Glioblastoma Cell Proliferation and Migration by Targeting SOX9

miR-30c has been acknowledged as a tumor suppressor in various human cancers, such as ovarian cancer, gastric cancer, and prostate cancer. However, the role of miR-30c in glioblastoma (GBM) needs to be investigated. In our study, we found that the expression of miR-30c was significantly downregulated in GBM tissues and cell lines. We found that overexpression of miR-30c inhibited cellular proliferation of GBM cells in vitro and in vivo. More GBM cells were arrested in the G₀ phase after miR-30c overexpression. Moreover, we showed that miR-30c overexpression suppressed the migration and invasion of GBM cells. Mechanistically, we found that SOX9 was a direct target of miR-30c in GBM cells. Overexpression of miR-30c inhibited the mRNA and protein levels of SOX9 in GBM cells. Moreover, there was a negative correlation between the expression of miR-30c and SOX9 in GBM tissues. Finally, we showed that restoration of SOX9 in GBM cells reversed the proliferation, migration, and invasion of GBM cells transfected with miR-30c mimic. Collectively, our results demonstrated that miR-30c suppressed the proliferation, migration, and invasion of GBM cells via targeting SOX9.     

BMP4 augments the survival of hepatocellular carcinoma (HCC) cells under hypoxia and hypoglycemia conditions by promoting the glycolysis pathway

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death worldwide although its pathogenic mechanism remains to be fully understood. Unlike normal cells, most cancer cells rely on aerobic glycolysis and are more adaptable to the microenvironment of hypoxia and hypoglycemia. Bone Morphogenetic Protein 4 (BMP4) plays important roles in regulating proliferation, differentiation, invasion and migration of HCC cells. We have recently shown that BMP4 plays an important role in regulating glucose metabolism although the effect of BMP4 on glucose metabolic reprogramming of HCC is poorly understood. In this study, we found that BMP4 was highly expressed in HCC tumor tissues, as well as HCC cell lines that were tolerant to hypoxia and hypoglycemia. Mechanistically, we demonstrated that BMP4 protected HCC cells from hypoxia and hypoglycemia by promoting glycolysis since BMP4 up-regulated glucose uptake, the lactic acid production, the ATP level, and the activities of rate limiting enzymes of glycolysis (including HK2, PFK and PK). Furthermore, we demonstrated that BMP4 up-regulated HK2, PFKFB3 and PKM2 through the canonical Smad signal pathway as SMAD5 directly bound to the promoter of PKM. Collectively, our findings shown that BMP4 may play an important role in regulating glycolysis of HCC cells under hypoxia and hypoglycemia condition, indicating that novel therapeutics may be developed to target BMP4-regulated glucose metabolic reprogramming in HCC.     

下调Rab11基因对宫颈癌HeLa/SiHa 细胞侵袭迁移的影响及机制探讨

背景与目的：Rab11基因在宫颈癌细胞中高表达,可能与细胞恶性转化相关。本研究采用RNA干扰技术下调Rab11基因表达,并探讨其对宫颈癌HeLa/SiHa细胞侵袭迁移的影响及可能的相关机制。方法：将HeLa/SiHa细胞分为2组：阴性对照组(转染阴性对照的小干扰RNA)和Rab11 siRNA干扰组(转染小干扰Rab11siR-NA)。蛋白[质]印迹法(Western blot)检测Rab11干扰效果,检测转染Rab11 siRNA后,侵袭相关蛋白Rac1、基质金属蛋白酶2(matrix metalloproteinase 2,MMP2)和MMP9表达的变化;细胞划痕损伤实验检测细胞迁移;Transwell实验检测细胞侵袭;细胞免疫荧光实验从形态学角度探索在小干扰Rab11后Rac1蛋白在细胞膜上聚集位置的变化。结果：转染小干扰Rab11siRNA到HeLa/SiHa细胞后,Rab11蛋白表达受到高效抑制(P<0.01);细胞迁移、侵袭能力受到抑制(P<0.05),Rac1蛋白表达明显下调(P<0.01),MMP2、MMP9蛋白表达下调(P<0.05), Rab11 siRNA处理组细胞运动前端细胞膜下Rac1蛋白聚集量减少。结论：Rab11基因表达下调可以抑制HeLa/SiHa细胞的迁移和侵袭,其机制可能与Rac1、MMP2和MMP9蛋白表达量下降及Rac1定位的改变有关。     

HK2通过Akt1/p-Akt1上调Cdc42表达促进宫颈癌细胞迁移和侵袭

目的:探究己糖激酶2（HK2）通过Akt1/p-Akt1/Cdc42促进宫颈癌细胞迁移和侵袭的作用机制。方法:G418压力筛选并获取稳定表达HK2蛋白的HeLa和SiHa细胞系;Western blot和细胞免疫化学鉴定HK2蛋白在HeLa和SiHa细胞系中的表达水平;细胞划痕实验检测HK2对HeLa和SiHa体外划痕愈合能力的影响;Transwell迁移、侵袭实验检测HK2对HeLa和SiHa细胞体外迁移和侵袭能力的影响;GEPIA数据库分别分析宫颈癌中HK2的表达与Akt1、Cdc42表达的相关性;Western blot检测Akt1、p-Akt1、Cdc42蛋白在HK2过表达的HeLa细胞和SiHa细胞中的表达情况;在HK2过表达的HeLa、SiHa细胞中应用Akt1/p-Akt1抑制剂MK2206观察Cdc42的表达及细胞迁移和侵袭能力的变化。结果:成功构建HK2稳定表达的HeLa、SiHa细胞系;过表达HK2促进了HeLa、SiHa细胞的划痕愈合能力,促进了HeLa、SiHa细胞的体外迁移和侵袭;GEPIA在线数据库结果显示在宫颈癌中HK2表达与Akt1、Cdc42表达均呈正相关;过表达HK2上调了Akt1、p-Akt1、Cdc42蛋白在HeLa、SiHa细胞中的表达;在HK2过表达HeLa、SiHa细胞中,MK2206的使用抑制了HK2对Cdc42表达上调及细胞迁移和侵袭的促进作用。结论:HK2可能通过Akt1/p-Akt1途径上调Cdc42蛋白的表达促进HeLa和SiHa细胞的迁移和侵袭。     

Inhibitory effects of Arhgap6 on cervical carcinoma cells

Ras homology GTPase activation protein 6 (Arhgap6), as a member of the rhoGAP family of proteins, performs vital functions on the regulation of actin polymerization at the plasma membrane during several cellular processes. The role of Arhgap6 in the progression and development of cancer remains nearly unknown. This study aimed at exploring the effects of Arhgap6 on cervical carcinoma. Human cervical cancer cells HeLa and SiHa were transduced with a lentivirus targeting Arhgap6 (Arhgap6+), while CaSki and C4-1 cells were transfected with miRNA. Cell proliferation was identified by Cell Counting Kit-8 (CCK-8). Cell cycle distribution and cell apoptosis were identified by flow cytometry. The capacity of cell migration, invasion, and adhesion were detected by Transwell assay. Further, quantitative real-time PCR (qRT-PCR) and western blot were used to analyze the expression levels of Arhgap6 and several tumor-related genes. Co-immunoprecipitation assay was performed to validate the interaction between Arhgap6 and Rac3 (Ras-related C3 botulinum toxin substrate 3). Results showed that Arhgap6 inhibited cell proliferation, migration, invasion, and adhesion of cervical carcinoma, induced cell apoptosis, and caused cell cycle arrest in the G0/G1 phase (n?=?3, p?<?0.05). Expression of the tumor suppressor genes and oncogenes were up- and down-regulated respectively by Arhgap6, and Rac3 was proved to be the target of Arhgap6. Besides, in in vivo assays, tumor size and weight were destructed in Arhgap6+ athymic nude mouse. This study indicated that Arhgap6 may play a role in the treatment of cervical cancer as a tumor supressor.     

Rac1活化在大肠癌细胞SW480迁移侵袭中的作用

目的研究Racl的活化在大肠癌迁移侵袭中的作用。方法对大肠癌SW480细胞株,分别导入活化的Rac1 L61重组体和对照用质粒;采用配体结合免疫共沉淀法通过Western blot检测细胞中活化Rac1的含量,进一步用。Transwell小室研究具有不同活性Rac1的SW480细胞其迁移及侵袭能力。结果SW480细胞的转染效率高达80%以上,配体结合免疫共沉淀结果显示,转染Rac1 L61重组体后Rac1的活性显著高于对照组;应用Transwell小室对SW480细胞迁移及侵袭能力研究时,发现Rac1活性高的实验组迁移及侵袭的细胞数显著高于对照组(迁移细胞数43±9:22±5, P<0.01;侵袭细胞数73±13:38±1,P<0.01)。结论Rac1的活化在大肠癌迁移侵袭中起重要的作用。     

Stimulation of neoplastic mouse lung cell proliferation by alveolar macrophage-derived, insulin-like growth factor-1 can be blocked by inhibiting MEK and PI3K activation

Background

Colorectal cancer is a common disease that involves genetic alterations, such as inactivation of tumour suppressor genes and activation of oncogenes. Among them are RAS and BRAF mutations, which rarely coexist in the same tumour. Individual members of the Rho (Ras homology) GTPases contribute with distinct roles in tumour cell morphology, invasion and metastasis. The aim of this study is to dissect cell migration and invasion pathways that are utilised by BRAF^V600E as compared to KRAS^G12V and HRAS^G12V oncoproteins. In particular, the role of RhoA (Ras homolog gene family, member A), Rac1 (Ras-related C3 botulinum toxin substrate 1) and Cdc42 (cell division cycle 42) in cancer progression induced by each of the three oncogenes is described.

Methods

Colon adenocarcinoma cells with endogenous as well as ectopically expressed or silenced oncogenic mutations of BRAF^V600E, KRAS^G12V and HRAS^G12V were employed. Signalling pathways and Rho GTPases were inhibited with specific kinase inhibitors and siRNAs. Cell motility and invasion properties were correlated with cytoskeletal properties and Rho GTPase activities.

Results

Evidence presented here indicate that BRAF^V600E significantly induces cell migration and invasion properties in vitro in colon cancer cells, at least in part through activation of RhoA GTPase. The relationship established between BRAF^V600E and RhoA activation is mediated by the MEK-ERK pathway. In parallel, KRAS^G12V enhances the ability of colon adenocarcinoma cells Caco-2 to migrate and invade through filopodia formation and PI3K-dependent Cdc42 activation. Ultimately increased cell migration and invasion, mediated by Rac1, along with the mesenchymal morphology obtained through the Epithelial-Mesenchymal Transition (EMT) were the main characteristics rendered by HRAS^G12V in Caco-2 cells. Moreover, BRAF and KRAS oncogenes are shown to cooperate with the TGFβ-1 pathway to provide cells with additional transforming properties.

Conclusion

This study discriminates oncogene-specific cell migration and invasion pathways mediated by Rho GTPases in colon cancer cells and reveals potential new oncogene-specific characteristics for targeted therapeutics.     

RasGRF2 promotes migration and invasion of colorectal cancer cells by modulating expression of MMP9 through Src/Akt/NF-κB pathway

Ras-specific guanine nucleotide-releasing factor 2 (RasGRF2) is a member of the guanine nucleotide exchange factors family which is expressed in a variety of tissues and cancer. However, the role of RasGRF2 in cancer is less reported, especially in colorectal cancer(CRC). Hence, the present study aimed to investigated the function of RasGRF2 and ways in which it affects tumor progression in CRC samples and cell lines. We first measured RasGRF2 mRNA level in 26 paired tumor and nontumor colon tissues after colon cancer surgical resection, and determined RasGRF2 protein level in 97 paired paraffin-embedded colon cancer tissues, and found that levels of RasGRF2 mRNA and protein were increased in colorectal tumor tissues, compared with adjacent non-tumor tissues. We then examined the effects of RasGRF2 knockdown on proliferation, migration and invasion were analyzed in CRC cells (SW480, HCT116 and LS174T). HCT116 cells with RasGRF2 knockdown were injected into the tail vein in nude mice to yield metastatic model, and tumor metastasis was measured as well. We found that knockdown of RasGRF2 in CRC cells reduced their migration and invasion in vitro and metastasis in mice. Furthermore, we explored the underlying molecular mechanism for RasGRF2-mediated CRC migration and invasion. The results showed that knockdown of RasGRF2 in CRC cells impairing the expression of MMP9 and inhibiting the activation of Src/Akt and NF-κB signaling. We conclude that RasGRF2 plays a role in controlling migration and invasion of CRC and modulates the expression of MMP9 through Src/PI 3-kinase and the NF-κB pathways.     

Dominant-negative Rac increases both inherent and ionizing radiation-induced cell migration in C6 rat glioma cells

Rho-like GTPases, including Cdc42, Rac1 and RhoA, regulate distinct actin cytoskeleton changes required for cell adhesion, migration and invasion. In the present study, we examined the role of Rac signaling in inherent migration, as well as radiation-induced migration, of rat glioma cells. Stable overexpression of dominant-negative Rac1N17 in a C6 rat glioma cell line (C6-RacN17) promoted cell migration, and ionizing radiation further increased this migration. Migration was accompanied by decreased expression of the focal adhesion molecules FAK and paxillin. Focal contacts and actin stress fibers were also reduced in C6-RacN17 cells. Downstream effectors of Rac include JNK and p38 MAP kinases. Irradiation transiently activated p38, JNK and ERK1/2 MAP kinases in C6-RacN17 cells, while p38 and JNK were constitutively activated in C6 control cells. Blocking JNK activity with JNK inhibitor SP600125 inhibited migration, suggesting that the JNK pathway may regulate radiation-induced, as well as inherent, migration of C6-RacN17 cells. Additionally, the radiation-induced migration increase was also inhibited by SB203580, a specific inhibitor of p38 MAP kinase. However, PD98059, a MEK kinase 1 inhibitor, failed to influence migration. This is the first evidence that suppression of Rac signaling may be involved in invasion or metastasis of glioma cells before and/or after radiotherapy. These data further suggest that radiotherapy for malignant glioma needs to be used with caution because of the potential for therapy-induced cell migration or invasion and that pharmacological inhibition of cell migration and invasion through targeting the Rac signaling pathway may represent a new approach for improving the therapeutic efficacy of radiotherapy for malignant glioma.     

Twist promotes reprogramming of glucose metabolism in breast cancer cells through PI3K/AKT and p53 signaling pathways

Twist, a key regulator of epithelial-mesenchymal transition (EMT), plays an important role in the development of a tumorigenic phenotype. Energy metabolism reprogramming (EMR), a newly discovered hallmark of cancer cells, potentiates cancer cell proliferation, survival, and invasion. Currently little is known about the effects of Twist on tumor EMR. In this study, we found that glucose consumption and lactate production were increased and mitochondrial mass was decreased in Twist-overexpressing MCF10A mammary epithelial cells compared with vector-expressing MCF10A cells. Moreover, these Twist-induced phenotypic changes were augmented by hypoxia. The expression of some glucose metabolism-related genes such as PKM2, LDHA, and G6PD was also found to be upregulated. Mechanistically, activated β1-integrin/FAK/PI3K/AKT/mTOR and suppressed P53 signaling were responsible for the observed EMR. Knockdown of Twist reversed the effects of Twist on EMR in Twist-overexpressing MCF10A cells and Twist-positive breast cancer cells. Furthermore, blockage of the β1-integrin/FAK/PI3K/AKT/mTOR pathway by siRNA or specific chemical inhibitors, or rescue of p53 activation can partially reverse the switch of glucose metabolism and inhibit the migration of Twist-overexpressing MCF10A cells and Twist-positive breast cancer cells. Thus, our data suggest that Twist promotes reprogramming of glucose metabolism in MCF10A-Twist cells and Twist-positive breast cancer cells via activation of the β1-integrin/FAK/PI3K/AKT/mTOR pathway and inhibition of the p53 pathway. Our study provides new insight into EMR.     

Tumor-suppressive sphingosine-1-phosphate receptor-2 counteracting tumor-promoting sphingosine-1-phosphate receptor-1 and sphingosine kinase 1 - Jekyll Hidden behind Hyde

Sphingosine-1-phosphate (S1P) is a plasma lipid mediator with multiple roles in mammalian development, physiology and pathophysiology. It is constitutively produced mostly by erythrocytes by the action of sphingosine kinase 1 (SphK1), resulting in high (～0.5 micromolar) steady-state plasma S1P content and steep S1P concentration gradient imposed between plasma/lymph/tissue interstitial fluid. S1P is also locally produced by activated platelets and tumor cells, in the latter case SphK1 is a downstream target of activated Ras mutant and hypoxia, and is frequently upregulated especially in advanced stages of tumors. Most if not all of the S1P actions in vertebrates are mediated through evolutionarily conserved G protein-coupled S1P receptor family. Ubiquitously expressed mammalian subtypes S1PR1, S1PR2 and S1PR3 mediate pleiotropic actions of S1P in diverse cell types, through coupling to distinctive repertoire of heterotrimeric G proteins. S1PR1 and S1PR3 mediate directed cell migration toward S1P through coupling to G(i) and activating Rac, a Rho family small G protein essential for cell migration. Indeed, S1PR1 expressed in lymphocytes directs their egress from lymph nodes into lymph and recirculation, serving as the target for downregulation by the immunosuppressant FTY720 (fingolimod). S1PR1 in endothelial cells plays an essential role in vascular maturation in embryonic stage, and mediates angiogenic and vascular protective roles of S1P which include eNOS activation and maintenance of barrier integrity. It is likely that S1PR1 and SphK1 expressed in host endothelial cells and tumor cells act in concert in a paracrine loop to contribute to tumor angiogenesis, tumor invasion and progression. In sharp contrast, S1PR2 mediates S1P inhibition of Rac at the site downstream of G(12/13)-mediated Rho activation, thus identified as the first G protein-coupled receptor that negatively regulates Rac and cell migration. S1PR2 could also mediate inhibition of Akt and cell proliferation/survival signaling via Rho-ROCK-PTEN pathway. S1PR2 expressed in tumor cells mediates inhibition of cell migration and invasion in vitro and metastasis in vivo. Moreover, S1PR2 expressed in host endothelial cells and tumor-infiltrating myeloid cells in concert mediates potent inhibition of tumor angiogenesis and tumor growth in vivo, with inhibition of VEGF expression and MMP9 activity. These recent findings provide further basis for S1P receptor subtype-specific, novel therapeutic tactics for individualized treatment of patients with cancer.     

Effects of Homeodomain Protein CDX2 Expression on the Proliferation and Migration of Lovo Colon Cancer Cells

The homeobox gene, CDX2, plays a major role in development, especially in the gut, and also functions as a tumor suppressor in the adult colon. In the present study, we investigated the effects of CDX2 expression on the proliferation, migration, and apoptosis of the human colon cancer cell line, Lovo. Lovo cells exogenously expressing CDX2 exhibited no significant differences in the percentage of cells in G1- and S-phase or in apoptosis, as determined by flow cytometry. MTT assay also confirmed that CDX2 expression had no effect on proliferation in these cells. Interestingly, conditioned medium collected from CDX2-overexpressing Lovo cells showed a significant decrease in secretion of MMP-2 and the invasive potential of these cells was significantly inhibited. Collectively, these data suggest that CDX2 may play a critical role in the migration and metastasis of colon carcinoma and over-expression of CDX2 in colon cancer cells markedly inhibits invasion. Based on these results, exogenous expression of CDX2 might be a promising option in the treatment of colon carcinoma.