LDHA is necessary for the tumorigenicity of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common lethal tumors in the world, and the development of new therapeutic targets is needed. Recent studies have shown that aerobic glycolysis, also known as the Warburg effect, mediated the anti-apoptotic effects in cancer cells. Lactate dehydrogenase A (LDHA) which executed the final step of aerobic lactate production has been reported to be involved in the tumor progression. However, the function of LDHA in ESCC has not been investigated. In this study, it was found that LDHA was up-regulated in ESCC clinical samples. Knockdown of the expression of LDHA inhibited cell growth and cell migration in vitro as well as tumorigenesis in vivo. With regard to the molecular mechanism, silencing the expression of LDHA was related to decreased AKT activation and cyclin D1 expression and increased cleavage of PARP and caspase 8. Taken together, our findings suggest that LDHA plays an important role in the progression of ESCC by modulating cell growth, and LDHA might be a potential therapeutic target in ESCC.     

p53/Lactate dehydrogenase A axis negatively regulates aerobic glycolysis and tumor progression in breast cancer expressing wild‐type p53

Tumor suppressor p53 is a master regulator of apoptosis and plays key roles in cell cycle checkpoints. p53 responds to metabolic changes and alters metabolism through several mechanisms in cancer. Lactate dehydrogenase A (LDHA), a key enzyme in glycolysis, is highly expressed in a variety of tumors and catalyzes pyruvate to lactate. In the present study, we first analyzed the association and clinical significance of p53 and LDHA in breast cancer expressing wild‐type p53 (wt‐p53) and found that LDHA mRNA levels are negatively correlated with wt‐p53 but not with mutation p53 mRNA levels, and low p53 and high LDHA expression are significantly associated with poor overall survival rates. Furthermore, p53 negatively regulates LDHA expression by directly binding its promoter region. Moreover, a series of LDHA gain‐of‐function and rescore experiments were carried out in breast cancer MCF7 cells expressing endogenous wt‐p53, showing that ectopic expression of p53 decreases aerobic glycolysis, cell proliferation, migration, invasion and tumor formation of breast cancer cells and that restoration of the expression of LDHA in p53‐overexpressing cells could abolish the suppressive effect of p53 on aerobic glycolysis and other malignant phenotypes. In conclusion, our findings showed that repression of LDHA induced by wt‐p53 blocks tumor growth and invasion through downregulation of aerobic glycolysis in breast cancer, providing new insights into the mechanism by which p53 contributes to the development and progression of breast cancer.     

H19 promotes aerobic glycolysis,proliferation, and immune escape of gastric cancer cells through the microRNA-519d-3p/lactate dehydrogenase A axis

Long noncoding RNAs (lncRNAs) have been investigated in multiple human cancers including gastric cancer (GC). Our research aims to explore the role of H19 in aerobic glycolysis, proliferation, and immune escape of GC cells. The expression of H19 in GC samples was analyzed using Gene Expression Profiling Interactive Analysis, Gene Expression Omnibus data, and real-time quantitative PCR analysis. Relative quantification of glucose consumption and lactate production from cell supernatant were applied to assess the aerobic glycolysis of GC cells. Subcellular fractionation, luciferase reporter, and western blot assays certified the binding between genes. Cell Counting Kit-8 and colony formation assays were used to determine GC cell proliferation. Flow cytometry, ELISA, and real-time quantitative PCR assays were applied to analyze the immunosuppressive effect of H19. H19 was highly expressed in samples of patients with GC, and associated with tumor growth in vivo. H19 knockdown suppressed glucose consumption, lactate production, and proliferation of GC cells by regulating the microRNA (miR)-519d-3p/lactate dehydrogenase A (LDHA) axis. Both miR-519d-3p depletion and LDHA overexpression could reverse the H19 knockdown-induced decrease in aerobic glycolysis and proliferation. Moreover, conditioned medium from stable knockdown H19 GC cells modulated the activity of immune cells including γδT cells, Jurkat cells, and tumor-associated macrophages in a miR-519d-3p/LDHA/lactate axis-dependent manner. The H19/miR-519d-3p/LDHA axis mainly contributed to aerobic glycolysis, proliferation, and immune escape of GC cells.     

annexin Ⅰ基因在胰腺癌中的表达及其对胰腺癌细胞生物学行为的影响

目的探讨annexinⅠ基因在胰腺癌发生过程中的作用。方法通过免疫组化方法确认annexinⅠ基因在胰腺癌组织中的高表达,合成annexinⅠ基因的小分子RNA干扰片断(siRNA)及无关序列,并构建RNA干扰片断的重组真核表达载体,将重组真核载体稳定转染胰腺癌细胞。通过RNA干扰(RNAi)的方法,敲低annexinⅠ基因在mRNA水平的表达。通过逆转录聚合酶链反应(RT- PCR)、免疫细胞化学、流式细胞技术和二苯基溴化四氮唑蓝(MTT)法,证实annexinⅠ基因的表达被敲低后,对胰腺癌细胞的生长速度、细胞形态、细胞周期、凋亡情况进行观察和检测。结果敲低annexinⅠ基因的表达后,胰腺癌细胞形态发生了显著的变化,呈多形性、空泡样变性以及脂滴形成等,G1期明显延长,出现了明显的凋亡,凋亡率分别为29.8%和18.8%,胰腺癌细胞的恶性表型被抑制。结论annexinⅠ基因在胰腺癌的发生过程中起到了调控肿瘤细胞周期、促进肿瘤细胞生长增殖和抑制凋亡的重要作用。     

MUC16-mediated activation of mTOR and c-MYC reprograms pancreatic cancer metabolism

MUC16, a transmembrane mucin, facilitates pancreatic adenocarcinoma progression and metastasis. In the current studies, we observed that MUC16 knockdown pancreatic cancer cells exhibit reduced glucose uptake and lactate secretion along with reduced migration and invasion potential, which can be restored by supplementing the culture media with lactate, an end product of aerobic glycolysis. MUC16 knockdown leads to inhibition of mTOR activity and reduced expression of its downstream target c-MYC, a key player in cellular growth, proliferation and metabolism. Ectopic expression of c-MYC in MUC16 knockdown pancreatic cancer cells restores the altered cellular physiology. Our LC-MS/MS based metabolomics studies indicate global metabolic alterations in MUC16 knockdown pancreatic cancer cells, as compared to the controls. Specifically, glycolytic and nucleotide metabolite pools were significantly decreased. We observed similar metabolic alterations that correlated with MUC16 expression in primary tumor tissue specimens from human pancreatic adenocarcinoma cancer patients. Overall, our results demonstrate that MUC16 plays an important role in metabolic reprogramming of pancreatic cancer cells by increasing glycolysis and enhancing motility and invasiveness.     

Lactate dehydrogenase A negatively regulated by miRNAs promotes aerobic glycolysis and is increased in colorectal cancer

Reprogramming metabolism of tumor cells is a hallmark of cancer. Lactate dehydrogenase A (LDHA) is frequently overexpressed in tumor cells. Previous studies has shown higher levels of LDHA is related with colorectal cancer (CRC), but its role in tumor maintenance and underlying molecular mechanisms has not been established. Here, we investigated miRNAs-induced changes in LDHA expression. We reported that colorectal cancer express higher levels of LDHA compared with adjacent normal tissue. Knockdown of LDHA resulted in decreased lactate and ATP production, and glucose uptake. Colorectal cancer cells with knockdown of LDHA had much slower growth rate than control cells. Furthermore, we found that miR-34a, miR-34c, miR-369-3p, miR-374a, and miR-4524a/b target LDHA and regulate glycolysis in cancer cells. There is a negative correlation between these miRNAs and LDHA expression in colorectal cancer tissues. More importantly, we identified a genetic loci newly associated with increased colorectal cancer progression, rs18407893 at 11p15.4 (in 3′-UTR of LDHA), which maps to the seed sequence recognized by miR-374a. Cancer cells overexpressed miR-374a has decreased levels of LDHA compared with miR-374a-MUT (rs18407893 at 11p15.4). Taken together, these novel findings provide more therapeutic approaches to the Warburg effect and therapeutic targets of cancer energy metabolism.     

Cyclooxygenase 2 promoted the tumorigenecity of pancreatic cancer cells

Pancreatic cancer is one of the leading causes of cancer-related death in the world. It is very urgent to find new therapeutic targets and improve the treatment. Cyclooxygenase 2 (Cox2), a regulator of inflammation signaling, has been found to be involved in tumorigenesis of various tumor types. However, its biological functions in pancreatic cancer cells are not fully understood. Here, we found that the expression of Cox2 was elevated in pancreatic cancer tissues compared with that in the paired normal tissues. The over-expression of Cox2 in pancreatic cancer cells promoted cell proliferation and migration, while the knockdown of the expression of Cox2 inhibited the tumorigenesis of pancreatic cancer cells in vitro and in vivo. Mechanistically, Cox2 regulated the expression of multiple genes involved in cell growth, migration, and cell apoptosis. Taken together, our study revealed the pivotal function of Cox2 in pancreatic cancer, and Cox2 might be an important therapeutic target for the treatment.     

PTTG regulates the metabolic switch of ovarian cancer cells via the c-myc pathway

Human pituitary tumor-transforming gene (PTTG) is a proto-oncogene involved in the development, invasion, and metastasis of many types of cancer, including ovarian cancer. However, little is known about the role of PTTG in the metabolic shift of ovarian cancer cells. In our study, we show that PTTG expression was positively correlated with the differentiation degree of ovarian cancer tissue. In addition, PTTG suppression by specific shRNA could inhibit the proliferation of ovarian cancer cells A2780 and SKOV-3. Furthermore, aerobic glycolysis was suppressed and oxidative phosphorylation was increased in ovarian cancer cells after PTTG suppression. We further found that the expression of c-myc and several crucial enzymes involved in aerobic glycolysis (e.g., PKM2, LDHA, and glucose transporter 1 (GLUT-1)) were downregulated by PTTG knockwown. Overexpression of c-myc could prevent the metabolic shift induced by PTTG knockwown. Together, our findings suggest that the oncogene PTTG promotes the progression of ovarian cancer cells, and its loss resists tumor development, in part, by regulating cellular metabolic reprogramming that supports cell growth and proliferation via c-myc pathway.     

IRF-2 is over-expressed in pancreatic cancer and promotes the growth of pancreatic cancer cells

Pancreatic cancer is one of the most malignant diseases in the world. Interferon regulator factor 2 (IRF-2), an interferon regulatory factor, has been known to act as an oncogene in distinct types of cancer. In this study, we found that the expression of IRF-2 was up-regulated in primary pancreatic cancer samples and associated with tumor size, differentiation, tumor–node–metastasis stage, and survival of the patients. In pancreatic cancer cells, knockdown on the expression of IRF-2 inhibited cell growth in the liquid culture and on the soft agar. Mechanistically, IRF-2 modulated the growth of pancreatic cancer cells through regulating proliferation and apoptosis effectors, such as cyclin D1 and BAX. Collectively, these results suggest that IRF-2 plays an important role in the tumorigenesis of pancreatic cancer and down-regulation of IRF-2 would be a new treatment target for pancreatic cancer.     

NPM1 activates metabolic changes by inhibiting FBP1 while promoting the tumorigenicity of pancreatic cancer cells

The nucleophosmin (NPM1) activates cancer development and progression in many malignant tumors. However, the regulatory role and underlying mechanisms of NPM1 in pancreatic cancer are unknown. In this study, we showed that NPM1 was up-regulated in PDAC, which indicated a poor prognosis. We also identified NPM1could stimulate aerobic glycolysis and repress fructose-1, 6-bisphosphatase 1 (FBP1) in pancreatic cancer cells. Restoring FBP1 expression partially reversed the tumor-promoting effects of NPM1, while the loss of FBP1 in PDAC tissues was indicative of a poorer prognosis. In sum, NPM1 promotes aerobic glycolysis and tumor progression in patients with pancreatic cancer by inhibiting FBP1.     

Attenuation of LDHA expression in cancer cells leads to redox-dependent alterations in cytoskeletal structure and cell migration

Aerobic glycolysis, the preferential use of glycolysis even in the presence of oxygen to meet cellular metabolic demands, is a near universal feature of cancer. This unique type of metabolism is thought to protect cancer cells from damaging reactive oxygen species (ROS) produced in the mitochondria. Using the cancer cell line MDA-MB-435 it is shown that shRNA mediated knockdown of lactate dehydrogenase A (LDHA), a key mediator of aerobic glycolysis, results in elevated mitochondrial ROS production and a concomitant decrease in cell proliferation and motility. Redox-sensitive proteins affected by oxidative stress associated with LDHA knockdown were identified by Redox 2D-PAGE and mass spectrometry. In particular, tropomyosin (Tm) isoforms Tm4, Tm5NM1 and Tm5NM5, proteins involved in cell migration and cytoskeletal dynamics, exhibited changes in disulfide bonding and co-localized with peri-nuclear actin aggregates in LDHA knockdown cells. In contrast, treatment with the thiol-based antioxidant N-acetylcysteine promoted the relocalization of Tms to cortical actin microfilaments and partially rescued the migration defects associated with attenuated LDHA expression. These results suggest that aerobic glycolysis and reduced mitochondrial ROS production create an environment conducive to cytoskeletal remodeling; key events linked to the high cell motility associated with cancer.     

Graviola: a novel promising natural-derived drug that inhibits tumorigenicity and metastasis of pancreatic cancer cells in vitro and in vivo through altering cell metabolism

Pancreatic tumors are resistant to conventional chemotherapies. The present study was aimed at evaluating the potential of a novel plant-derived product as a therapeutic agent for pancreatic cancer (PC). The effects of an extract from the tropical tree Annona Muricata, commonly known as Graviola, was evaluated for cytotoxicity, cell metabolism, cancer-associated protein/gene expression, tumorigenicity, and metastatic properties of PC cells. Our experiments revealed that Graviola induced necrosis of PC cells by inhibiting cellular metabolism. The expression of molecules related to hypoxia and glycolysis in PC cells (i.e. HIF-1α, NF-κB, GLUT1, GLUT4, HKII, and LDHA) were downregulated in the presence of the extract. In vitro functional assays further confirmed the inhibition of tumorigenic properties of PC cells. Overall, the compounds that are naturally present in a Graviola extract inhibited multiple signaling pathways that regulate metabolism, cell cycle, survival, and metastatic properties in PC cells. Collectively, alterations in these parameters led to a decrease in tumorigenicity and metastasis of orthotopically implanted pancreatic tumors, indicating promising characteristics of the natural product against this lethal disease.     

p8 is a new target of gemcitabine in pancreatic cancer cells.

Gemcitabine is the only available chemotherapeutic treatment of pancreatic cancers. It is, however, moderately effective, showing a tumor response rate of only 12%. The aim of this work was to identify new pathways involved in the resistance of pancreatic cancer cells to gemcitabine, in the hope of developing new adjuvant strategies to enhance its therapeutic efficacy. Comparison of gene expression patterns of five human pancreatic cancer cell lines showing different degrees of resistance to gemcitabine revealed specific overexpression of several genes in the most resistant. One of them encoded the antiapoptotic p8 protein. We found that (a) knocking down p8 expression in gemcitabine-resistant cells promoted cell death and increased caspase-3 activity; (b) forced overexpression of p8 in gemcitabine-sensitive cells increased their resistance to gemcitabine-induced apoptosis; and (c) gemcitabine down-regulated p8 mRNA expression. These results suggest that, in pancreatic cancer cells, a large part of gemcitabine-induced apoptosis results from the inhibition of the constitutive antiapoptotic activity of p8. Hence, targeting the p8-associated pathway could be a new adjuvant therapy improving the response of patients with pancreatic cancer to gemcitabine treatment.     

DEPTOR has growth suppression activity against pancreatic cancer cells

DEPTOR was reported as a naturally occurring inhibitor of mTORC1 and mTORC2. The role of DEPTOR in the growth and survival of pancreatic cancer cells has not previously been determined. Here we report that while DEPTOR shows a cytoplasmic expression in both normal pancreatic acinar and islet cells in a patchy manner, its expression is reduced in PanIN1 and PanIN2 and completely lost in 100 out of 101 pancreatic ductal adenocarcinoma (PDAC) tissues. Ectopic DEPTOR expression in two pancreatic cancer cell lines, Panc-1 and Miapaca-2, caused a significant 1) suppression of anchorage-dependent growth in monolayer culture, particularly under conditions with growth factor deprivation; 2) decreased clonogenic survival, and 3) suppressed anchorage-independent growth in soft agar. These effects are attributable to moderate induction of apoptosis and growth arrest at the S and G2/M phases, in a cell line dependent manner. Furthermore, ectopic DEPTOR expression moderately inhibited mTORC1 activity, as demonstrated by reduced phosphorylation of S6K, S6, and 4E-BP1. Taken together, these data suggest that DEPTOR has a tumor suppressive activity against pancreatic cancer cells, and its loss of expression may contribute to pancreatic tumorigenesis.     

JQ1 suppresses tumor growth through downregulating LDHA in ovarian cancer

Amplification and overexpression of c-Myc is commonly seen in human ovarian cancers, and this could be a potentially novel therapeutic target for this disease. JQ1, a selective small-molecule BET bromodomain (BRDs) inhibitor, has been found to suppress tumor progression in several cancer cell types. Using ovarian cancer cell lines, a transgenic mouse model, and primary cell cultures from human ovarian cancer tissues, we demonstrated that JQ1 significantly suppressed cellular proliferation and induced cell cycle arrest and apoptosis in ovarian cancer cells and mouse model via targeting c-Myc. In addition, JQ1 had multiple influences on cancer metabolism, particularly in the aerobic glycolysis pathway. JQ1 reduced both the activity and phosphorylation of LDHA, inhibited lactate production, and decreased the energy supply to ovarian cancer cell lines and tumors. Taken together, our findings suggest that JQ1 is an efficacious anti-tumor agent in ovarian cancer that is associated with cell cycle arrest, induction of apoptosis and alterations of metabolism.     

Glycolysis in the progression of pancreatic cancer

Metabolic reprogramming, as a key hallmark of cancers, leads to the malignant behavior of pancreatic cancer, which is closely related to tumor development and progression, as well as the supportive tumor microenvironments. Although cells produce adenosine triphosphate (ATP) from glucose by glycolysis when lacking oxygen, pancreatic cancer cells elicit metabolic conversion from oxide phosphorylation to glycolysis, which is well-known as “Warburg effect”. Glycolysis is critical for cancer cells to maintain their robust biosynthesis and energy requirement, and it could promote tumor initiation, invasion, angiogenesis, and metastasis to distant organs. Multiple pathways are involved in the alternation of glycolysis for pancreatic cancer cells, including UHRF1/SIRT4 axis, PRMT5/FBW7/cMyc axis, JWA/AMPK/FOXO3a/FAK axis, KRAS/TP53/TIGAR axis, etc. These signaling pathways play an important role in glycolysis and are potential targets for the treatment of pancreatic cancer. Mutations in glycolytic enzymes (such as LDH, PKM2, and PGK1) also contribute to the early diagnosis and monitoring of pancreatic cancer. In this review, we summarized the recent advances on the mechanisms for glycolysis in pancreatic cancer and the function of glycolysis in the progression of pancreatic cancer, which suggested new targets for cancer diagnosis and treatment.     

CircSMARCA5通过miR-4295/PTEN轴调控糖酵解抑制胃癌细胞增殖和侵袭

背景与目的:胃癌是常见的消化系统恶性肿瘤。作者既往研究发现circSMARCA5在胃癌中表达降低并能够抑制胃癌进展,但其具体机制目前仍不清楚。本研究探究circSMARCA5抑制胃癌细胞增殖和侵袭的分子机制。方法:采用细胞计数试剂盒-8(cell counting kit-8,CCK-8)和transwell实验检测过表达circSMARCA5对胃癌细胞增殖和侵袭能力的影响。通过检测细胞外酸化率、葡萄糖摄取水平和乳酸生成量,分析过表达circSMARCA5对胃癌细胞糖酵解的影响。采用实时荧光定量聚合酶链式反应(real-time fluorescent quantitative polymerase chain reaction,RTFQ-PCR)检测circSMARCA5、miR-4295和PTEN的基因表达,采用蛋白质印迹法(Western blot)检测GLUT1和LDHA的蛋白水平。建立BACB/c裸小鼠皮下移植瘤模型,观察过表达circSMARCA5对移植瘤生长的影响,利用免疫组织化学方法检测两组皮下瘤中GLUT1、LDHA的表达水平及Ki-67增殖指数。通过双荧光素酶报告基...