PKM2 promotes glucose metabolism through a let-7a-5p/Stat3/hnRNP-A1 regulatory feedback loop in breast cancer cells

Replenishment of TCA cycle intermediates and long-noncoding RNAs regulation in breast cancer

The tricarboxylic acid (TCA) cycle is an essential interface that coordinates cellular metabolism and is as a primary route determining the fate of a variety of fuel sources, including glucose, fatty acid and glutamate. The crosstalk of nutrients replenished TCA cycle regulates breast cancer (BC) progression by changing substrate levels-induced epigenetic alterations, especially the methylation, acetylation, succinylation and lactylation. Long non-coding RNAs (lncRNA) have dual roles in inhibiting or promoting energy reprogramming, and so altering the metabolic flux of fuel sources to the TCA cycle, which may regulate epigenetic modifications at the cellular level of BC. This narrative review discussed the central role of the TCA cycle in interconnecting numerous fuels and the induced epigenetic modifications, and the underlying regulatory mechanisms of lncRNAs in BC.

Downregulation of CIAPIN1 regulates the proliferation, migration and glycolysis of breast cancer cells via inhibition of STAT3 pathway

Cytokine-induced apoptosis inhibitor 1 (CIAPIN1) is a protein that regulates apoptosis and programmed cell death. This research aims to evaluate its potential role in inhibiting breast cancer cell proliferation, migration, and glycolysis and uncover its underlying molecular mechanism. We collected breast cancer tissue samples from eight patients between January 2019 and June 2023 in our Hospital to analyse CIAPIN1 expression. We transfected human breast cancer cell lines (MCF7, MDA-MB-231, MDA-MB-453, and MDA-MB-468) with siRNA of CIAPIN1. Finally, we determined protein expression using RT-qPCR and Western blotting. CIAPIN1 expression was elevated in both breast cancer tissue and serum. Overexpression of CIAPIN1 detected in the breast cancer cell lines MCF7 and MDA-MB-468. In addition, CIAPIN1 overexpression increased cell proliferation and migration rate. CIAPIN1 downregulation suppressed cell proliferation while elevated cellular apoptosis, reactive oxygen species (ROS) production and oxidative stress in breast cancer cells. Moreover, CIAPIN1 inhibition remarkably suppressed pyruvate, lactate and adenosine triphosphate (ATP) production and reduced the pyruvate kinase M2 (PKM2) protein expression and phosphorylation of signal transducer and activator of transcription 3 (STAT3) in breast cancer cells. Downregulation of CIAPIN1 suppresses cell proliferation, migration and glycolysis capacity in breast cancer cells by inhibiting the STAT3/PKM2 pathway.

Understanding the molecular pathway of triclosan-induced ADHD-like behaviour: Involvement of the hnRNPA1-PKM2-STAT3 feedback loop

Triclosan (TCS) is an environmental pollutant. In recent years, there has been increasing level of concern regarding the potential toxicity of TCS in animals and humans, especially its effects on the nervous system. However, whether TCS induces ADHD-like behaviour and the mechanism by which it affects neural function are unclear. The impact of 60 days of continuous exposure to TCS on the behaviour of offspring rats was assessed in this research. According to the results of this study, TCS exposure led to ADHD-like behaviour in offspring rats and activated microglia in the prefrontal cortex (PFC), inducing inflammatory factor release. In vitro studies showed that TCS increased the levels of inflammatory cytokines, including interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α, in HMC3 cells. More importantly, we found that TCS regulated the STAT3 pathway by upregulating PKM2 via hnRNPA1. In summary, this study suggested that TCS can induce ADHD-like behaviour in offspring rats and continuously activate HMC3 microglia through the hnRNPA1-PKM2-STAT3 feedback loop, promoting inflammatory cytokine secretion.

All-trans-retinoic acid modulates glycolysis via H19 and telomerase: the role of mir-let-7a in estrogen receptor-positive breast cancer cells

BACKGROUND

Breast cancer (BC) is the most commonly diagnosed cancer in women. Treatment approaches that differ between estrogen-positive (ER+) and triple-negative BC cells (TNBCs) and may subsequently affect cancer biomarkers, such as H19 and telomerase, are an emanating delight in BC research. For instance, all-trans-Retinoic acid (ATRA) could represent a potent regulator of these oncogenes, regulating microRNAs, mostly let-7a microRNA (miR-let-7a), which targets the glycolysis pathway, mainly pyruvate kinase M2 (PKM2) and lactate dehydrogenase A (LDHA) enzymes. Here, we investigated the potential role of ATRA in H19, telomerase, miR-let-7a, and glycolytic enzymes modulation in ER + and TNBC cells.

METHODS

MCF-7 and MDA-MB-231 cells were treated with 5 µM ATRA and/or 100 nM fulvestrant. Then, ATRA-treated or control MCF-7 cells were transfected with either H19 or hTERT siRNA. Afterward, ATRA-treated or untreated MDA-MB-231 cells were transfected with estrogen receptor alpha ER(α) or beta ER(β) expression plasmids. RNA expression was evaluated by RT‒qPCR, and proteins were assessed by Western blot. PKM2 activity was measured using an NADH/LDH coupled enzymatic assay, and telomerase activity was evaluated with a quantitative telomeric repeat amplification protocol assay. Student's t-test or one-way ANOVA was used to analyze data from replicates.

RESULTS

Our results showed that MCF-7 cells were more responsive to ATRA than MDA-MB-231 cells. In MCF-7 cells, ATRA and/or fulvestrant decreased ER(α), H19, telomerase, PKM2, and LDHA, whereas ER(β) and miR-let-7a increased. H19 or hTERT knockdown with or without ATRA treatment showed similar results to those obtained after ATRA treatment, and a potential interconnection between H19 and hTERT was found. However, in MDA-MB-231 cells, RNA expression of the aforementioned genes was modulated after ATRA and/or fulvestrant, with no significant effect on protein and activity levels. Overexpression of ER(α) or ER(β) in MDA-MB-231 cells induced telomerase activity, PKM2 and LDHA expression, in which ATRA treatment combined with plasmid transfection decreased glycolytic enzyme expression.

CONCLUSIONS

To the best of our knowledge, our study is the first to elucidate a new potential interaction between the estrogen receptor and glycolytic enzymes in ER + BC cells through miR-let-7a.

The Regulatory Network of hnRNPs Underlying Regulating PKM Alternative Splicing in Tumor Progression

One of the hallmarks of cancer is metabolic reprogramming in tumor cells, and aerobic glycolysis is the primary mechanism by which glucose is quickly transformed into lactate. As one of the primary rate-limiting enzymes, pyruvate kinase (PK) M is engaged in the last phase of aerobic glycolysis. Alternative splicing is a crucial mechanism for protein diversity, and it promotes PKM precursor mRNA splicing to produce PKM2 dominance, resulting in low PKM1 expression. Specific splicing isoforms are produced in various tissues or illness situations, and the post-translational modifications are linked to numerous disorders, including cancers. hnRNPs are one of the main components of the splicing factor families. However, there have been no comprehensive studies on hnRNPs regulating PKM alternative splicing. Therefore, this review focuses on the regulatory network of hnRNPs on PKM pre-mRNA alternative splicing in tumors and clinical drug research. We elucidate the role of alternative splicing in tumor progression, prognosis, and the potential mechanism of abnormal RNA splicing. We also summarize the drug targets retarding tumorous splicing events, which may be critical to improving the specificity and effectiveness of current therapeutic interventions.

hnRNP A1 dysfunction alters RNA splicing and drives neurodegeneration in multiple sclerosis (MS)

Neurodegeneration is the primary driver of disease progression in multiple sclerosis (MS) resulting in permanent disability, creating an urgent need to discover its underlying mechanisms. Herein, we establish that dysfunction of the RNA binding protein heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) results in differential of binding to RNA targets causing alternative RNA splicing, which contributes to neurodegeneration in MS and its models. Using RNAseq of MS brains, we discovered differential expression and aberrant splicing of hnRNP A1 target RNAs involved in neuronal function and RNA homeostasis. We confirmed this in vivo in experimental autoimmune encephalomyelitis employing CLIPseq specific for hnRNP A1, where hnRNP A1 differentially binds and regulates RNA, including aberrantly spliced targets identified in human samples. Additionally, dysfunctional hnRNP A1 expression in neurons caused neurite loss and identical changes in splicing, corroborating hnRNP A1 dysfunction as a cause of neurodegeneration. Collectively, these data indicate hnRNP A1 dysfunction causes altered neuronal RNA splicing, resulting in neurodegeneration in MS.

MicroRNA Let-7a association with glycolysis-induced autophagy in locally advanced gastric cancer: Their role in prognosis and FLOT chemotherapy resistance

Locally advanced gastric cancer (LAGC) still poses a clinical challenge despite multimodality treatment due to multidrug resistance (MDR). Recently, research suggested that autophagy and metabolic regulation may be potential anticancer targets due to their crucial roles in MDR. Let-7a participates in glycolytic and autophagic regulations which are both essential for tumor progression and resistance to therapy. This study used IHC stains; GLUT4 and LC3B to evaluate glycolysis and autophagy respectively. Moreover, mRNA Let-7a was detected by quantitative reverse transcription PCR (q-PCR) in 53 cases of LAGC. Elevated glycolysis and autophagy in LAGC tissue specimens as indicated by high GLUT4 and LC3B expression were significantly associated with adverse prognostic factors such as high pathological grade, positive nodal metastasis, and advanced T stage. Lower Let-7a levels were significantly associated with high tumor grade and advanced T stage. A significant positive correlation between GLUT4 and LC3B expression was detected. Significant inverse correlations between let7a level and IHC expression of both GLUT4 and LC3B were found. Elevated glycolysis and autophagy were significantly associated with poor overall survival (OS). Furthermore, low levels of let-7a were significantly associated with poor OS compared to high levels. Glycolysis and autophagy in LAGC were significantly associated with poor FLOT chemotherapy response. Let7a mRNA relative expression was significantly decreased in cases showing post therapy partial response and sustained disease. Multivariate analysis showed that histologic tumor type, high GLUT4 and high LC3B expression were independent factors associated with poor OS. Poor survival and post FLOT chemotherapy resistance in LAGC cases were significantly related to elevated glycolysis, elevated autophagy, and reduced Let-7a expression. Accordingly, combined therapeutic targeting of these pathways could enhance chemosensitivity in LAGC.

PTP4A1 promotes oral squamous cell carcinoma (OSCC) metastasis through altered mitochondrial metabolic reprogramming

PTP4A1 (Protein tyrosine phosphatase 4A1) is a protein tyrosine phosphatase that regulates a range of pro-oncogenic signaling pathways. Here, we report a novel role for PTP4A1 in oral squamous cell carcinoma (OSCC) growth and development. We show that PTP4A1 is frequently overexpressed in OSCC cells and tissues compared to adjacent non-tumor tissue. In OSCC, the overexpression of PTP4A1 increased cell growth and invasion in vitro, and enhanced tumor progression in vivo. At the molecular level, PTP4A1 was found to regulate mitochondrial metabolic reprogramming to enhance the invasive capacity of OSCC cells. Mechanistically, these effects were mediated through binding to pyruvate kinase isoenzyme M2 (PKM2) to promote its expression and aconitase 2 (ACO2) to enhance its degradation. Together, these data reveal PTP4A1 as a viable target for OSCC therapeutics.

Differential miRNA expression of hypoxic MCF7 and PANC-1 cells

Background

Hypoxia plays a critical role in the tumor microenvironment by affecting cellular proliferation, metabolism, apoptosis, DNA repair, and chemoresistance. Since hypoxia provokes a distinct shift of microRNA, it is important to illustrate the relative contribution of each hypoxamiR to cancer progression.

Aims

The present study aims to shed light on the hypoxamiRs that are involved in pancreatic and breast cancer progression to highlight novel targets for the development of new therapies.

Methods

For 20 cycles, MCF7 breast cancer cells and PANC-1 pancreatic cancer cells were subjected to chronic cyclic hypoxia, which consisted of 72 hours of hypoxia followed by 24 hours of reoxygenation. After 10 and 20 cycles of hypoxia, miRNA expression alterations were profiled using RT-PCR array and further analyzed using a visual analytics platform. The MTT cell proliferation assay was used to determine hypoxic cells' chemoresistance to doxorubicin.

Results

Under chronic cyclic hypoxia, hypoxic PANC-1 cells have a comparable doubling time with their normoxic counterparts, whereas hypoxic MCF7 cells show a massive increase in doubling time when compared to their normoxic counterparts. Both hypoxic cell lines developed EMT-like phenotypes as well as doxorubicin resistance. According to the findings of miRNet, 6 and 10 miRNAs were shown to play an important role in enriching six hallmarks of pancreatic cancer in the 10th and 20th cycles of hypoxia, respectively, while 7 and 11 miRNAs were shown to play an important role in enriching the four hallmarks of breast cancer in the 10th and 20th cycles of hypoxia, respectively.

Conclusions

miR-221, miR-21, miR-155, and miR-34 were found to be involved in the potentiation of hypoxic PANC-1 hallmarks at both the 10th and 20th cycles, while miR-93, miR-20a, miR-15, and miR-17 were found to be involved in the potentiation of hypoxic MCF7 hallmarks at both the 10th and 20th cycles. This variation in miRNA expression was also connected to the emergence of an EMT-like phenotype, alterations in proliferation rates, and doxorubicin resistance. The chemosensitivity results revealed that chronic cyclic hypoxia is critical in the formation of chemoresistant phenotypes in pancreatic and breast cancer cells. miR-181a and let-7e expression disparities in PANC1, as well as miR-93, miR-34, and miR-27 expression disparities in MCF7, may be associated with the formation of chemoresistant MCF7 and PANC-1 cells following 20 cycles of chronic cyclic hypoxia. Indeed, further research is needed since the particular mechanisms that govern these processes are unknown.

Non-coding RNAs in breast cancer: with a focus on glucose metabolism reprogramming

Breast cancer is the tumor with the highest incidence in women worldwide. According to research, the poor prognosis of breast cancer is closely related to abnormal glucose metabolism in tumor cells. Changes in glucose metabolism in tumor cells are an important feature. When sufficient oxygen is available, cancer cells tend to undergo glycolysis rather than oxidative phosphorylation, which promotes rapid proliferation and invasion of tumor cells. As research deepens, targeting the glucose metabolism pathway of tumor cells is seen as a promising treatment. Non-coding RNAs (ncRNAs), a recent focus of research, are involved in the regulation of enzymes of glucose metabolism and related cancer signaling pathways in breast cancer cells. This article reviews the regulatory effect and mechanism of ncRNAs on glucose metabolism in breast cancer cells and provides new ideas for the treatment of breast cancer.

Oncogenic metabolic reprogramming in breast cancer: focus on signaling pathways and mitochondrial genes

Oncogenic metabolic reprogramming impacts the abundance of key metabolites that regulate signaling and epigenetics. Metabolic vulnerability in the cancer cell is evident from the Warburg effect. The research on metabolism in the progression and survival of breast cancer (BC) is under focus. Oncogenic signal activation and loss of tumor suppressor are important regulators of tumor cell metabolism. Several intrinsic and extrinsic factors contribute to metabolic reprogramming. The molecular mechanisms underpinning metabolic reprogramming in BC are extensive and only partially defined. Various signaling pathways involved in the metabolism play a significant role in the modulation of BC. Notably, PI3K/AKT/mTOR pathway, lactate-ERK/STAT3 signaling, loss of the tumor suppressor Ras, Myc, oxidative stress, activation of the cellular hypoxic response and acidosis contribute to different metabolic reprogramming phenotypes linked to enhanced glycolysis. The alterations in mitochondrial genes have also been elaborated upon along with their functional implications. The outcome of these active research areas might contribute to the development of novel therapeutic interventions and the remodeling of known drugs.

Energy metabolism pathways in breast cancer progression: The reprogramming, crosstalk, and potential therapeutic targets

Breast cancer (BC) is a malignant tumor that seriously endangers health in women. BC, like other cancers, is accompanied by metabolic reprogramming. Among energy metabolism-related pathways, BC exhibits enhanced glycolysis, tricarboxylic acid (TCA) cycle, pentose phosphate pathway (PPP), glutamate metabolism, and fatty acid metabolism activities. These pathways facilitate the proliferation, growth and migration of BC cells. The progression of BC is closely related to the alterations in the activity or expression level of several metabolic enzymes, which are regulated by the intrinsic factors such as the key signaling and transcription factors. The metabolic reprogramming in the progression of BC is attributed to the aberrant expression of the signaling and transcription factors associated with the energy metabolism pathways. Understanding the metabolic mechanisms underlying the development of BC will provide a druggable potential for BC treatment and drug discovery.

Reduced CircSMOC1 Level Promotes Metabolic Reprogramming via PTBP1 (Polypyrimidine Tract-Binding Protein) and miR-329-3p in Pulmonary Arterial Hypertension Rats

BACKGROUND

Pulmonary arterial hypertension maintains rapid cell proliferation and vascular remodeling through metabolic reprogramming. Recent studies suggested that circRNAs play important role in pulmonary vascular remodeling and pulmonary arterial smooth muscle cells proliferation. However, the relationship between circRNA, cell proliferation, and metabolic reprogramming in pulmonary arterial hypertension has not been investigated.

METHODS

RNA-seq and qRT-PCR reveal the differential expression profile of circRNA in pulmonary arteries of pulmonary arterial hypertension rat models. Transfection was used to examine the effects of circSMOC1 on pulmonary artery smooth muscle cells, and the roles of circSMOC1 in vivo were investigated by adenoassociated virus. Mass spectrometry, RNA pull-down, RNA immunoprecipitation, and dual-luciferase reporter assay were performed to investigate the signaling pathway of circSMOC1 regulating the metabolic reprogramming.

RESULTS

CircSMOC1 was significantly downregulated in pulmonary arteries of pulmonary arterial hypertension rats. CircSMOC1 knockdown promoted proliferation and migration and enhanced aerobic glycolysis of pulmonary artery smooth muscle cells. CircSMOC1 overexpression in vivo alleviates pulmonary vascular remodeling, right ventricular pressure, and right heart hypertrophy. In the nucleus, circSMOC1 directly binds to PTBP1 (polypyrimidine tract-binding protein), competitively inhibits the specific splicing of PKM (pyruvate kinase M) premRNA, resulting in the upregulation of PKM2 (pyruvate kinase M2), the key enzyme of aerobic glycolysis, to enhance glycolysis. In the cytoplasm, circSMOC1 acted as a miR-329-3p sponge, and its reduction in pulmonary arterial hypertension suppressed PDHB (pyruvate dehydrogenase E1 subunit beta) expression, leading to the impairment of mitochondrial oxidative phosphorylation.

CONCLUSIONS

circSMOC1 is crucially involved in the metabolic reprogramming of pulmonary artery smooth muscle cells through PTBP1 and miR-329-3p to regulate pulmonary vascular remodeling in pulmonary arterial hypertension.

Spartin: At the crossroad between ubiquitination and metabolism in cancer

SPART is a gene coding for a multifunctional protein called spartin, localized in various organelles of human cells. Mutations in the coding region are responsible for a hereditary form of spastic paraplegia called Troyer syndrome while the epigenetic silencing has been demonstrated for some types of tumors. The main functions of this gene are associated to endosomic trafficking and receptor degradation, microtubule interaction, cytokinesis, fatty acids and oxidative metabolism. Spartin has been shown to be a target regulated by STAT3 and localizes also at the level of the mitochondrial outer membrane, where it forms part of a complex maintaining the integrity of the membrane potential. The most recent evidences report a downregulation of spartin in tumor tissues when compared to adjacent normal samples. This intriguing evidence supports further research aimed at clarifying the role of this protein in cancer development and metabolism.

Metabolic Pathways in Breast Cancer Reprograming: An Insight to Non-Coding RNAs

Cancer cells reprogram their metabolisms to achieve high energetic requirements and produce precursors that facilitate uncontrolled cell proliferation. Metabolic reprograming involves not only the dysregulation in glucose-metabolizing regulatory enzymes, but also the enzymes engaging in the lipid and amino acid metabolisms. Nevertheless, the underlying regulatory mechanisms of reprograming are not fully understood. Non-coding RNAs (ncRNAs) as functional RNA molecules cannot translate into proteins, but they do play a regulatory role in gene expression. Moreover, ncRNAs have been demonstrated to be implicated in the metabolic modulations in breast cancer (BC) by regulating the metabolic-related enzymes. Here, we will focus on the regulatory involvement of ncRNAs (microRNA, circular RNA and long ncRNA) in BC metabolism, including glucose, lipid and glutamine metabolism. Investigation of this aspect may not only alter the approaches of BC diagnosis and prognosis, but may also open a new avenue in using ncRNA-based therapeutics for BC treatment by targeting different metabolic pathways.

Heterogeneous nuclear ribonucleoprotein A/B: an emerging group of cancer biomarkers and therapeutic targets

Heterogeneous nuclear ribonucleoprotein A/B (hnRNPA/B) is one of the core members of the RNA binding protein (RBP) hnRNPs family, including four main subtypes, A0, A1, A2/B1 and A3, which share the similar structure and functions. With the advance in understanding the molecular biology of hnRNPA/B, it has been gradually revealed that hnRNPA/B plays a critical role in almost the entire steps of RNA life cycle and its aberrant expression and mutation have important effects on the occurrence and progression of various cancers. This review focuses on the clinical significance of hnRNPA/B in various cancers and systematically summarizes its biological function and molecular mechanisms.

LINC00094/miR-19a-3p/CYP19A1 axis affects the sensitivity of ER positive breast cancer cells to Letrozole through EMT pathway

The endocrine therapy resistance of breast cancer is the difficulty and challenge to be urgently solved in the current treatment. In this study, we examined the effects of noncoding RNA LINC00094 and miR-19a-3p on breast cancer in vivo and in vitro by RT-QPCR, Western Blot, luciferase assay, immunofluorescence and drug sensitivity tests. The plasma level of CYP19A1 in patients with breast cancer resistance was lower than that in drug sensitive patients. Compared with normal subjects, miR-19a-3p was highly expressed in plasma of patients with breast cancer. miR-19a-3p is highly expressed in estrogen receptor positive breast cancer cells. The expression of miR-19a-3p promoted the migration and EMT of breast cancer cells and reduced the sensitivity of breast cancer to Letrozole. LINC00094 sponge adsorbed miR-19a-3p. LINC00094 promotes the expression of CYP19A1, the target gene of miR-19a-3p, and inhibits the EMT process of breast cancer, ultimately promoting the sensitivity of ER-positive breast cancer cells to Letrozole. This study found a new mechanism of Letrozole sensitivity in ER positive breast cancer.

Overexpression of c-Myc-dependent heterogeneous nuclear ribonucleoprotein A1 promotes proliferation and inhibits apoptosis in NOTCH1-mutated chronic lymphocytic leukemia cells

BACKGROUND

NOTCH1 mutation is an essential molecular biologic aberration in chronic lymphocytic leukemia (CLL). CLL patients with NOTCH1 mutation have shown an unfavorable survival and a poor response to chemoimmunotherapy. This study aims to present the mechanisms of adverse prognosis caused by NOTCH1 mutation from the perspective of the splicing factor heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1).

METHODS

The microarray data in Gene Expression Omnibus datasets were analyzed by bioinformatics and the function of hnRNPA1 was checked by testing the proliferation and apoptosis of CLL-like cell lines. Afterward, quantitative reverse transcription-polymerase chain reaction and Western blotting were applied to explore the relationship among NOTCH1, c-Myc, and hnRNPA1.

RESULTS

RNA splicing was found to play a vital part in NOTCH1-mutated CLL cells; hence, hnRNPA1 was selected as the focus of this study. Higher expression of hnRNPA1 validated in primary NOTCH1-mutated CLL samples could promote proliferation and inhibit apoptosis in CLL. The expression of hnRNPA1 increased when NOTCH1 signaling was activated by transfection with NOTCH1 intracellular domain (NICD)-overexpressed adenovirus vector and declined after NOTCH1 signaling was inhibited by NOTCH1-shRNA. Higher expression of c-Myc was observed in NICD-overexpressed cells and hnRNPA1 expression was downregulated after applying c-Myc inhibitor 10058-F4. Moreover, in NICD-overexpressed cells, hnRNPA1 expression decreased through c-Myc inhibition.

CONCLUSION

Overexpression of c-Myc-dependent hnRNPA1 could promote proliferation and inhibit apoptosis in NOTCH1-mutated CLL cells, which might partly account for the poor prognosis of patients with NOTCH1 mutation.

Potential of PKM2 as a drug target in mouse models with type 1 diabetes mellitus

BACKGROUND

This study aimed to determine the effect of PKM2 knockout in STZ induced type 1 diabetes mellitus (T1D) mouse models and to explore the possible mechanism.

METHOD

PKM2fl/fl C57BL/6 mouse was backcrossed with Ins-1cre C57BL/6 mouse to generate β-cell-specific PKM2 knockout mouse after tamoxifen administration. The expression level of PKM2 in pancreas tissues was detected by quantitative reverse-transcription polymerase chain reaction and western blot analysis. The blood glucose levels in STZ induced T1D mouse models were measured to validate the establishment of T1D models. The pathological changes of T1D mouse were examined by hematoxylin and eosin. The oxidative stress (OS) and inflammatory response in T1D mouse were determined by measuring the expression levels of malondialdehyde, superoxide dismutase, and 8-OHdG in pancreatic tissues and the serum levels of interleukin-6 and tumor necrosis factor-α. The ability to catabolize glucose was assessed through intraperitoneal glucose tolerance test and insulin tolerance test.

RESULTS

β-cell-specific PKM2 knockout was successfully achieved in PKM2fl/flcre+ mouse. T1D mouse with PKM2 knockdown had decreased blood glucose level and suppressed cell apoptosis. PKM2 knockout in T1D mouse attenuated β cell injury. OS and inflammatory response in T1D mouse with PKM2 knockout were also suppressed compared with T1D mouse without PKM2 knockout.

CONCLUSION

PKM2 knockout in T1D mouse can attenuate OS and inflammatory response as well as decrease blood glucose level, suggesting the potential of PKM2 as a drug target for T1D treatment.

LncRNA RSU1P2-microRNA let-7a-Testis-Expressed Protein 10 axis modulates tumorigenesis and cancer stem cell-like properties in liver cancer

LncRNAs exert important functions in the modulation of tumorigenesis and cancer stem cell-like properties in liver cancer. However, the role of LncRNA Ras suppressor protein 1 pseudogene 2 (RSU1P2) in modulating tumorigenesis and cancer stem cell-like properties in liver cancer is still not known. In this study, the expression of LncRNA RSU1P2 was significantly elevated in liver cancer tissues and cells. Besides, knockdown of RSU1P2 repressed cell viability, invasion, epithelial-mesenchymal transition (EMT) of liver cancer cells and the expressions of cancer stem cell-related genes, whereas facilitated the apoptosis of liver cancer cells. In addition, LncRNA RSU1P2 can interact with microRNA let-7a (let-7a), and repress let-7a expression. Testis-Expressed Protein 10 (Tex10) was identified to be a target of let-7a, and let-7a repressed Tex10 expression. Finally, RSU1P2 knockdown suppressed tumor volume, tumor weight, and EMT in a xenograft model. Therefore, LncRNA RSU1P2 promotes tumorigenesis and cancer stem cell-like properties in liver cancer through let-7a/Tex10 pathway.

Human papillomavirus16 E6 but not E7 upregulates GLUT1 expression in lung cancer cells by upregulating thioredoxin expression

Background and objective: E6 and E7 proteins in human papillomavirus (HPV) 16 are major oncogenes in several types of tumors, including lung cancer. Previous studies have demonstrated that both E6 and E7 oncoproteins can upregulate GLUT1 protein and mRNA expression levels in lung cancer cells. Thus, the present study aimed to investigate the main differences in the molecular mechanisms of GLUT1 expression regulated by E6 and E7. Methods: The double directional genetic manipulation and immunofluorescence were performed to explore the molecular mechanism of E6 or E7 upregulating the expression of GLUT1 in H1299 and A549 cell lines. Results: The overexpression of E6 in well-established lung cancer cell lines upregulated thioredoxin (Trx) protein expression. Notably, plasmid transfection or small interfering RNA transfection with E7 had no regulatory effect on Trx expression. As an important disulfide reductase of the intracellular antioxidant system, Trx plays important role in maintaining oxidative stress balance and protecting cells from oxidative damage. The overexpression of Trx increased the activation of NF-κB by upregulating p65 expression and promoting p65 nuclear translocation, and further upregulated GLUT1 protein and mRNA expression levels. The results of the present study demonstrated that E6, but not E7, upregulated GLUT1 expression in lung cancer cells by activating NF-κB due to the participation of Trx. Conclusion: These results suggest that Trx plays an important role in the pathogenesis of HPV-associated lung cancer, and propose a novel therapeutic target for HPV-associated lung cancer.

The Metabolism Reprogramming of microRNA Let-7-Mediated Glycolysis Contributes to Autophagy and Tumor Progression

Cancer is usually a result of abnormal glucose uptake and imbalanced nutrient metabolization. The dysregulation of glucose metabolism, which controls the processes of glycolysis, gives rise to various physiological defects. Autophagy is one of the metabolic-related cellular functions and involves not only energy regeneration but also tumorigenesis. The dysregulation of autophagy impacts on the imbalance of metabolic homeostasis and leads to a variety of disorders. In particular, the microRNA (miRNA) Let-7 has been identified as related to glycolysis procedures such as tissue repair, stem cell-derived cardiomyocytes, and tumoral metastasis. In many cancers, the expression of glycolysis-related enzymes is correlated with Let-7, in which multiple enzymes are related to the regulation of the autophagy process. However, much recent research has not comprehensively investigated how Let-7 participates in glycolytic reprogramming or its links to autophagic regulations, mainly in tumor progression. Through an integrated literature review and omics-related profiling correlation, this review provides the possible linkage of the Let-7 network between glycolysis and autophagy, and its role in tumor progression.

Interleukin -1β Promotes Lung Adenocarcinoma Growth and Invasion Through Promoting Glycolysis via p38 Pathway

Background

There is a close relationship among inflammation, glycolysis, and tumors. The IL-1 family includes important inflammatory cytokines, among which IL-1β has been widely studied. In this study, we focused on the effect of IL-1β on glycolysis of lung adenocarcinoma (LUAD) cells in vivo and in vitro and explored its possible mechanisms.

Methods

A bioinformatic database and quantitative real-time PCR were used to analyze the expression of glycolysis-related enzyme genes and their correlations with IL1β in human LUAD samples. The human LUAD cell line A549 and Lewis lung carcinoma LLC cell line were stimulated with IL-1β. In vitro treatment effects, including glycolysis level, migration, and invasion were evaluated with a glucose assay kit, lactate assay kit, Western blotting, wound healing, and the transwell method. We established a mouse model of subcutaneous tumors using LLC cells pretreated with IL-1β and analyzed in vivo treatment effects through positron-emission tomography-computed tomography and staining. Virtual screening and molecular dynamic simulation were used to screen potential inhibitors of IL-1β.

Results

Our results showed that IL1β was positively correlated with the expression of glycolysis-related enzyme genes in LUAD. Glycolysis, migration, and invasion significantly increased in A549 and LLC stimulated with IL-1β. In vivo, IL-1β increased growth, mean standard uptake value, and pulmonary tumor metastasis, which were inhibited by the glycolysis inhibitor 2-deoxy-D-glucose and p38-pathway inhibitors. Small molecular compound ZINC14610053 was suggested being a potential inhibitor of IL-1β.

Conclusion

IL-1β promotes glycolysis of LUAD cells through p38 signaling, further enhancing tumor-cell migration and invasion. These results show that IL-1β links inflammation to glycolysis in LUAD, and targeting IL-1β and the glycolysis pathway may be a potential therapeutic strategy for lung cancer.

EMT-cancer cells-derived exosomal miR-27b-3p promotes circulating tumour cells-mediated metastasis by modulating vascular permeability in colorectal cancer

BACKGROUND

Metastasis is the main cause of death in colorectal cancer (CRC). Circulating tumour cells (CTCs) are regarded as the precursor cells of metastasis. The CTCs, which underwent epithelial-mesenchymal transition (EMT), are associated with metastasis and responsible for poor prognosis. EMT cancer cells modulate endothelial permeability in the invasive front and facilitate cancer cell intravasation, resulting in CTCs-mediated distant metastasis. Exosomes derived from cancer cells are key mediators of cancer-host intercommunication. However, the mechanism by which EMT-tumour cells-derived exosomes modulate vascular permeability and promote CTCs generation has remained unclear.

METHODS

Exosomes isolation and purification were conducted by ultra-centrifugation. Exosomal miRNA was identified by sequencing followed by quantitative PCR. In vitro co-culture assay experiments were conducted to evaluate the effect of exosomal miR-27b-3p on the permeability of blood vessel endothelium. Dual-luciferase reporter assay, chromatin immunoprecipitation (ChIP) and RNA immunoprecipitation (RIP) were performed to investigate the underlying mechanism by which miR-27b-3p is packaged into exosomes. A mouse model was established to determine the role of exosomal miR-27b-3p in blood vessel permeability modulation in vivo.

RESULTS

We found that EMT-CRC cells attenuate the blood vessel barrier by transferring miR-27b-3p to human umbilical vein endothelial cells (HUVECs) in exosomes. Mechanically, miR-27b-3p atteuated the expression of vascular endothelial cadherin (VE-Cad) and p120 at the post-transcriptional level by binding to 3'-untranslated region of VE-Cad and p120 directly. The packaging of miR-27b-3p into exosomes was induced by heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1), which activated by STAT3. Clinically, miR-27b-3p up-regulated in CRC tissues. Plasma exosomal miR-27b-3p was positively correlated with malignant progression and CTC count in CRC patients. Our study reveals a novel mechanism by which EMT-CRC cells promote metastasis, increasing blood vessel permeability and facilitating the generation of CTCs.

CONCLUSION

Exosomal miR-27b-3p secreted by EMT-CRC cells increases blood vessel permeability and facilitates the generation of CTCs. Exosomal miR-27b-3p may become a promising biomarker for CRC metastasis.

The Crosstalk Between Signaling Pathways and Cancer Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide. Metabolic reprogramming represents an important cancer hallmark in CRC. Reprogramming core metabolic pathways in cancer cells, such as glycolysis, glutaminolysis, oxidative phosphorylation, and lipid metabolism, is essential to increase energy production and biosynthesis of precursors required to support tumor initiation and progression. Accumulating evidence demonstrates that activation of oncogenes and loss of tumor suppressor genes regulate metabolic reprogramming through the downstream signaling pathways. Protein kinases, such as AKT and c-MYC, are the integral components that facilitate the crosstalk between signaling pathways and metabolic pathways in CRC. This review provides an insight into the crosstalk between signaling pathways and metabolic reprogramming in CRC. Targeting CRC metabolism could open a new avenue for developing CRC therapy by discovering metabolic inhibitors and repurposing protein kinase inhibitors/monoclonal antibodies.

Esculetin inhibits endometrial cancer proliferation and promotes apoptosis via hnRNPA1 to downregulate BCLXL and XIAP

Endometrial cancer represents one of the most common gynecological tumors in the world. Advanced and relapsed patients rely on drug therapy. Therefore, it is extremely important to seek more effective targeted drugs. This study found that esculetin has an anti-tumor effect on endometrial cancer through cellular proliferation and apoptosis. At the same time, its anti-tumor effect has also been verified in human endometrial cancer xenograft models in nude mice. Western blot results showed that BCLXL, XIAP, and pAKT protein expression level were down-regulated. A pulldown experiment and LC-MS/MS analysis technology revealed that esculetin targets the hnRNPA1 protein. Cellular proliferation experiments following si-hnRNPA1 transfection verified the tumor-promoting effect of hnRNPA1 in endometrial cancer cells. Nuclear and cytoplasmic separation experiment demonstrated esculetin affecting the export of the hnRNPA1/mRNA complex from the nucleus into the cytoplasm. Thus, esculetin targets hnRNPA1, thereby downregulates BCLXL and XIAP mRNA transcription and translation, resulting in apoptosis and an arrest in proliferation.

hnRNP A/B Proteins: An Encyclopedic Assessment of Their Roles in Homeostasis and Disease

The hnRNP A/B family of proteins is canonically central to cellular RNA metabolism, but due to their highly conserved nature, the functional differences between hnRNP A1, A2/B1, A0, and A3 are often overlooked. In this review, we explore and identify the shared and disparate homeostatic and disease-related functions of the hnRNP A/B family proteins, highlighting areas where the proteins have not been clearly differentiated. Herein, we provide a comprehensive assembly of the literature on these proteins. We find that there are critical gaps in our grasp of A/B proteins' alternative splice isoforms, structures, regulation, and tissue and cell-type-specific functions, and propose that future mechanistic research integrating multiple A/B proteins will significantly improve our understanding of how this essential protein family contributes to cell homeostasis and disease.

Curcumin: Modulator of Key Molecular Signaling Pathways in Hormone-Independent Breast Cancer

Simple Summary

Breast cancer remains the most commonly diagnosed cancer and the leading cause of cancer death among females worldwide. It is a highly heterogeneous disease, classified according to hormone and growth factor receptor expression. Patients with triple negative breast cancer (TNBC) (estrogen receptor-negative/progesterone receptor-negative/human epidermal growth factor receptor (HER2)-negative) and hormone-independent HER2 overexpressing subtypes still represent highly aggressive behavior, metastasis, poor prognosis, and drug resistance. Thus, new alternative anticancer agents based on the use of natural products have been receiving enormous attention. In this regard, curcumin is a promising lead in cancer drug discovery due its ability to modulate a diverse range of molecular targets and signaling pathways. The current review has emphasized the underlying mechanism of curcumin anticancer action mediated through the modulation of PI3K/Akt/mTOR, JAK/STAT, MAPK, NF-ĸB, p53, Wnt/β-catenin, apoptosis, and cell cycle pathways in hormone-independent breast cancer, providing frameworks for future studies and insights to improve its efficiency in clinical practice.

Abstract

Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death among women worldwide. Despite the overall successes in breast cancer therapy, hormone-independent HER2 negative breast cancer, also known as triple negative breast cancer (TNBC), lacking estrogens and progesterone receptors and with an excessive expression of human epidermal growth factor receptor 2 (HER2), along with the hormone-independent HER2 positive subtype, still remain major challenges in breast cancer treatment. Due to their poor prognoses, aggressive phenotype, and highly metastasis features, new alternative therapies have become an urgent clinical need. One of the most noteworthy phytochemicals, curcumin, has attracted enormous attention as a promising drug candidate in breast cancer prevention and treatment due to its multi-targeting effect. Curcumin interrupts major stages of tumorigenesis including cell proliferation, survival, angiogenesis, and metastasis in hormone-independent breast cancer through the modulation of multiple signaling pathways. The current review has highlighted the anticancer activity of curcumin in hormone-independent breast cancer via focusing on its impact on key signaling pathways including the PI3K/Akt/mTOR pathway, JAK/STAT pathway, MAPK pathway, NF-ĸB pathway, p53 pathway, and Wnt/β-catenin, as well as apoptotic and cell cycle pathways. Besides, its therapeutic implications in clinical trials are here presented.

Discovery of a Fluorogenic Probe for In Situ Pyruvate Kinase M2 Isoform (PKM2) Labeling through Chemoselective SNAr with a Binding Site Lysine Residue

The key challenge of developing reaction-based turn-on probes is to establish latent electrophilic fluorophores exhibiting high reactivity only upon binding to a specific protein(s). Herein, we identified such a fluorophore, 6-arylthioether-substituted 3-cyano-1-oxo-1H-phenalene-2-carboxylate, which chemoselectively labels binding site Cys or Lys residues. Based on this fluorophore, we developed the first reaction-based turn-on pyruvate kinase M2 isoform (PKM2) fluorescent probe AT-OPC1, which selectively labels PKM2 with the binding site Lys305. The latent electrophilic reactivity of the fluorophore endows the probe with precise detection of the expression of PKM2 in situ by means of both in-gel fluorescence imaging at the proteome level and real-time no-wash cell imaging approaches, which has the potential to be applied in cancer diagnoses.

Let-7a-5p regulates the inflammatory response in chronic rhinosinusitis with nasal polyps

BACKGROUND

Let-7a-5p is demonstrated to be a tumor inhibitor in nasopharyngeal carcinoma. However, the role of let-7a-5p in chronic rhinosinusitis with nasal polyps (CRSwNP) has not been reported. This study is designed to determine the pattern of expression and role of let-7a-5p in CRSwNP.

METHODS

The expression level of let-7a-5p, TNF-α, IL-1β, and IL-6 in CRSwNP tissues and cells were detected by RT-qPCR. Western blot assay was carried out to measure the protein expression of the Ras-MAPK pathway. Dual luciferase reporter assay and RNA pull-down assay were used to explore the relationship between let-7a-5p and IL-6.

RESULTS

Let-7a-5p was significantly downregulated in CRSwNP tissues and cells. Moreover, the mRNA expression of TNF-α, IL-1β and IL-6 was increased in CRSwNP tissues, while let-7a-5p mimic inhibited the expression of TNF-α, IL-1β and IL-6. Besides that, let-7a-5p was negatively correlated with TNF-α, IL-1β and IL-6 in CRSwNP tissues. In our study, IL-6 was found to be a target gene of let-7a-5p. Additionally, let-7-5p mimic obviously reduced the protein levels of Ras, p-Raf1, p-MEK1 and p-ERK1/2, while IL-6 overexpression destroyed the inhibitory effect of let-7a-5p on the Ras-MAPK pathway in CRSwNP.

CONCLUSION

We demonstrated that let-7a-5p/IL-6 interaction regulated the inflammatory response through the Ras-MAPK pathway in CRSwNP.

Advances in Understanding Mitochondrial MicroRNAs (mitomiRs) on the Pathogenesis of Triple-Negative Breast Cancer (TNBC)

Triple-negative breast cancer (TNBC) is characterized by poor outcome and the most challenging breast cancer type to treat worldwide. TNBC manifests distinct profile of mitochondrial functions, which dictates reprogrammed metabolism, fosters tumor progression, and notably serves as therapeutic targets. Mitochondrial microRNAs (mitomiRs) are a group of microRNAs that critically modulate mitochondrial homeostasis. By a pathway-centric manner, mitomiRs tightly orchestrate metabolic reprogramming, redox status, cell apoptosis, mitochondrial dynamics, mitophagy, mitochondrial DNA (mtDNA) maintenance, and calcium balance, leading to an emerging field of study in various cancer types, including TNBC. We herein review the recent insights into the roles and mechanism of mitomiRs in TNBC and highlight its clinical value in diagnosis and prognosis as well as vital advances on therapeutics of preclinical and clinical studies.

PKM2 promotes cell metastasis and inhibits autophagy via the JAK/STAT3 pathway in hepatocellular carcinoma

Pyruvate kinase M2 (PKM2) is a member of the pyruvate kinase family. It has been recently reported that PKM2 displays non-metabolic activities. Nevertheless, understanding of the role of PKM2 in hepatocellular carcinoma (HCC) is insufficient. Therefore, our study aimed at exploring the impact of PKM2 on malignant growth, autophagy as well as invasion in HCC. Expression of PKM2 in HCC specimens was examined by qRT-PCR and western blot. PKM2 knock down was generated in vitro by shRNA. Activities of malignant cells as well as downstream pathways were assessed. The MTT assay was carried out to evaluate HCC proliferation, and the FACS assay was conducted to study cell death. Elevated PKM2 levels were observed in HCC samples. Knockdown (KD) of PKM2 triggered apoptosis as well as autophagy and inhibited migration and proliferation of HCC cells. Furthermore, PKM2 KD reinforced JAK/STAT3 pathway stimulation. STAT3 inhibition counteracted the impact of PKM2 on proliferation, autophagy, migration as well as cell death in HCC. To conclude, the findings of our research suggest that PKM2 reinforced metastasis and inhibited autophagy in HCC through the JAK/STAT3 pathway, and that PKM2 could serve as a promising target for HCC treatment.

MAPK pathway and SIRT1 are involved in the down-regulation of secreted osteopontin expression by genistein in metastatic cancer cells

AIM

The regulation of secreted osteopontin (OPN) expression by genistein and its functional sequel in the metastatic cancer cells (MDA-MB-435 and MDA-MB-231) was ascertained.

MAIN METHODS

Western blot and Real-Time PCR were used to analyse the proteins and mRNA transcripts, respectively. Possible transcriptional regulation of secreted OPN was analyzed by chromatin immunoprecipitation assay, bioinformatics analysis, transfection and luciferase reporter assay. The specific siRNAs and constitutive p-ERKs were used to evaluate the role of the MAPK pathway. The functional sequel of genistein in these cells was analyzed by colony formation-, migration- and invasion- assay.

KEY FINDINGS

Secreted OPN expression was inhibited (up to ~0.7-fold) by genistein in these cells. Genistein (50 μM) displayed a reduction in the aggressiveness of these cells concerning colony formation rate, migration, and invasion. The p-ERK½ was increased by ~2.5-fold and ~1.5-fold upon 50 μM genistein and 15 μM resveratrol treatments at 24 h, respectively. Knockdown of ERK½ and PD98059, the inhibitor of MEK, promoted secreted OPN expression in vitro in these cells; while, the transfection of the constitutive active ERK2 (L73P and S151D) decreased the secreted OPN expression. Further, silent mating type information regulation 2 homolog 1 (SIRT1) expression in the cells was increased (~1.6-fold) upon genistein treatment (50 μM) likewise with resveratrol (~1.5-fold), an activator for SIRT1. Knockdown of SIRT1 increased OPN mRNA transcripts expression level and secreted OPN protein level in these cells.

SIGNIFICANCE

MAPK pathway and SIRT1 activation are involved in the regulation of secreted OPN by genistein in these cells.

Regulation of Glycolysis by Non-coding RNAs in Cancer: Switching on the Warburg Effect

The “Warburg effect” describes the reprogramming of glucose metabolism away from oxidative phosphorylation toward aerobic glycolysis, and it is one of the hallmarks of cancer cells. Several factors can be involved in this process, but in this review, the roles of non-coding RNAs (ncRNAs) are highlighted in several types of human cancer. ncRNAs, including microRNAs, long non-coding RNAs, and circular RNAs, can all affect metabolic enzymes and transcription factors to promote glycolysis and modulate glucose metabolism to enhance the progression of tumors. In particular, the 5′-AMP-activated protein kinase (AMPK) and the phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathways are associated with alterations in ncRNAs. A better understanding of the roles of ncRNAs in the Warburg effect could ultimately lead to new therapeutic approaches for suppressing cancer.

Let-7a-5p inhibits triple-negative breast tumor growth and metastasis through GLUT12-mediated warburg effect

Triple-negative breast cancer (TNBC) is known for its aggressive phenotype with limited treatment modalities and poor prognosis. The Warburg effect (aerobic glycolysis) is a hallmark of cancer that serves as a promising target for diagnosis and therapy. However, how aerobic glycolysis regulates TNBC remains largely unknown. Here, we show that the glucose transporter (GLUT) family member GLUT12 promotes TNBC tumor growth and metastasis in vitro and in vivo through regulating aerobic glycolysis. MicroRNA let-7a-5p, a tumor suppressor, inhibited GLUT12 expression by targeting its 3'-untranslated region, and suppressed GLUT12-mediated TNBC tumor growth, metastasis, and glycolytic function, including alterations of glucose uptake, lactate production, ATP generation, extracellular acidification rate, and oxygen consumption rate. Inhibiting aerobic glycolysis abolished the ability of let-7a-5p and GLUT12 to regulate TNBC cell proliferation, migration and invasion. In TNBC patients, GLUT12 was significantly upregulated, and let-7a-5p expression was inversely correlated with GLUT12 expression. High expression of let-7a-5p and GLUT12 predicted better and worse clinical outcomes, respectively. Taken together, our results indicate that the let-7a-5p/GLUT12 axis plays key roles in TNBC tumor growth and metastasis, and aerobic glycolysis, and is a potential target for TNBC treatment.

RNA-binding proteins in tumor progression

RNA-binding protein (RBP) has a highly dynamic spatiotemporal regulation process and important biological functions. They are critical to maintain the transcriptome through post-transcriptionally controlling the processing and transportation of RNA, including regulating RNA splicing, polyadenylation, mRNA stability, mRNA localization, and translation. Alteration of each process will affect the RNA life cycle, produce abnormal protein phenotypes, and thus lead to the occurrence and development of tumors. Here, we summarize RBPs involved in tumor progression and the underlying molecular mechanisms whereby they are regulated and exert their effects. This analysis is an important step towards the comprehensive characterization of post-transcriptional gene regulation involved in tumor progression.

Non-coding RNAs: Key regulators of aerobic glycolysis in breast cancer

Although extensive research progress has been made in breast cancer in recent years, yet the morbidity and mortality rates of breast cancer are rising, making it the major disease that endangers women's health. Energy metabolism reprogramming is featured by a state termed "aerobic glycolysis" or the Warburg effect that glycolysis is preferred even under aerobic conditions in neoplastic diseases. Widely acknowledged as an emerging hallmark in cancers, this metabolic switch shows a sophisticated role in the pathogenesis of breast cancer. The regulating effect of non-coding RNAs (ncRNAs) composed of microRNAs, long non-coding RNAs and circular RNAs is closely related to the glycolysis in breast cancer. Therefore, understand the mechanisms of ncRNAs of aerobic glycolysis in breast cancer may provide new strategy for the disease.

Role of STAT3 signaling pathway in breast cancer

Breast cancer has grown to be the second leading cause of cancer-related deaths in women. Only a few treatment options are available for breast cancer due to the widespread occurrence of chemoresistance, which emphasizes the need to discover and develop new methods to treat this disease. Signal transducer and activator of transcription 3 (STAT3) is an early tumor diagnostic marker and is known to promote breast cancer malignancy. Recent clinical and preclinical data indicate the involvement of overexpressed and constitutively activated STAT3 in the progression, proliferation, metastasis and chemoresistance of breast cancer. Moreover, new pathways comprised of upstream regulators and downstream targets of STAT3 have been discovered. In addition, small molecule inhibitors targeting STAT3 activation have been found to be efficient for therapeutic treatment of breast cancer. This systematic review discusses the advances in the discovery of the STAT3 pathways and drugs targeting STAT3 in breast cancer. Video abstract.

Experimental Study of Hepatocellular Carcinoma Treatment by Shikonin Through Regulating PKM2

Objective

Shikonin is a natural product with many activities, including anti-cancer effects. Pyruvate kinase type M2 (PKM2) plays a crucial role in the growth of tumor cells. However, the effect of shikonin on PKM2 in hepatocellular carcinoma (HCC) is unclear.

Methods

Cell viability, apoptosis level, glucose uptake, and lactate production were detected in HCC cells. Lentivirus-overexpressed and -shRNA of PKM2 were used to verify the key target of shikonin. A xenograft mouse model was used to detect the efficacy of shikonin and its combination with sorafenib in vivo.

Results

Shikonin inhibited proliferation and glycolysis and induced apoptosis in HCC cells. Either PKM2-overexpressed or PKM2-shRNA alleviated or enhanced this effect. The results of CCK-8 showed that shikonin significantly inhibited cell viability of HCC cells. The levels of glucose uptake and lactate production were dramatically decreased by shikonin-treated. Results of flow cytometry and Western blot showed that the levels of apoptosis of HCC cells were significantly increased in a dose-dependent manner after shikonin treatment. In addition, shikonin enhanced the anti-cancer effect of sorafenib in vitro and in vivo. Our results showed that SK combined with sorafenib markedly inhibits tumor growth in HCC-transplanted nude mice compared to SK or sorafenib alone.

Conclusion

By inhibiting PKM2, shikonin inhibited proliferation and glycolysis and induced cell apoptosis in HCC cells. The effect of shikonin on tumor cell proliferation, apoptosis and glycolsis will make it promising drug for HCC patients.

Polo-like kinase 3 inhibits glucose metabolism in colorectal cancer by targeting HSP90/STAT3/HK2 signaling

Background

Polo-like kinase 3 (PLK3) has been documented as a tumor suppressor in several types of malignancies. However, the role of PLK3 in colorectal cancer (CRC) progression and glucose metabolism remains to be known.

Methods

The expression of PLK3 in CRC tissues was determined by immunohistochemistry. Cells proliferation was examined by EdU, CCK-8 and in vivo analyses. Glucose metabolism was assessed by detecting lactate production, glucose uptake, mitochondrial respiration, extracellular acidification rate, oxygen consumption rate and ATP production. Chromatin immunoprecipitation, luciferase reporter assays and co-immunoprecipitation were performed to explore the signaling pathway. Specific targeting by miRNAs was determined by luciferase reporter assays and correlation with target protein expression.

Results

PLK3 was significantly downregulated in CRC tissues and its low expression was correlated with worse prognosis of patients. In vitro and in vivo experiments revealed that PLK3 contributed to growth inhibition of CRC cells. Furthermore, we demonstrated that PLK3 impeded glucose metabolism via targeting Hexokinase 2 (HK2) expression. Mechanically, PLK3 bound to Heat shock protein 90 (HSP90) and facilitated its degradation, which led to a significant decrease of phosphorylated STAT3. The downregulation of p-STAT3 further suppressed the transcriptional activation of HK2. Moreover, our investigations showed that PLK3 was directly targeted by miR-106b at post-transcriptional level in CRC cells.

Conclusion

This study suggests that PLK3 inhibits glucose metabolism by targeting HSP90/STAT3/HK2 signaling and PLK3 may serve as a potential therapeutic target in colorectal cancer.

MicroRNA let-7a inhibits proliferation of breast cancer cell by downregulating USP32 expression

Background

The present study aimed to investigate the effect of microRNA (miR) let-7a on ubiquitin specific protease 32 (USP32) expression and its potential function in MCF-7 breast cancer (BCa) cell line.

Methods

BCa MCF-7 cells were transfected with hsa-miR let-7a mimics or inhibitors, then the USP32 expression was evaluated using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis in the transfected cells. USP32 as a target regulated by miR let-7a was confirmed via Dual-luciferase reporter assay. The effects of miR let-7a on the viability were determined using MTT assay and colony formation analysis.

Results

Western blot analysis revealed that miR let-7a mimics dramatically decreased the USP32 protein expression, whereas miR let-7a inhibitors increased the protein expression of USP32 compared with their controls in the MCF-7 cells. Dual-luciferase reporter assay showed that miR let-7a mimics could directly target the 3'-untranslated region (UTR) of USP32. Further, MTT assay and colony formation analysis showed that miR let-7a significantly inhibited cell proliferation of MCF-7 cells. However, overexpression of USP32 could reverse the effect of miR let-7a on MCF-7 cells proliferation.

Conclusions

Collectively, the results suggested that miR let-7a functions as a tumor suppressor to reduce proliferation by targeting USP32 in BCa cells.

Warburg effect and its role in tumourigenesis

Glucose is a crucial molecule in energy production and produces different end products in non-tumourigenic- and tumourigenic tissue metabolism. Tumourigenic cells oxidise glucose by fermentation and generate lactate and adenosine triphosphate even in the presence of oxygen (Warburg effect). The Na⁺/H⁺-antiporter is upregulated in tumourigenic cells resulting in release of lactate- and H⁺ ions into the extracellular space. Accumulation of lactate- and proton ions in the extracellular space results in an acidic environment that promotes invasion and metastasis. Otto Warburg reported that tumourigenic cells have defective mitochondria that produce less energy. However, decades later it became evident that these mitochondria have adapted with alterations in mitochondrial content, structure, function and activity. Mitochondrial biogenesis and mitophagy regulate the formation of new mitochondria and degradation of defective mitochondria in order to combat accumulation of mutagenic mitochondrial deoxyribonucleic acid. Tumourigenic cells also produce increase reactive oxygen species (ROS) resulting from upregulated glycolysis leading to pathogenesis including cancer. Moderate ROS levels exert proliferative- and prosurvival signaling, while high ROS quantities induce cell death. Understanding the crosstalk between aberrant metabolism, redox regulation, mitochondrial adaptions and pH regulation provides scientific- and medical communities with new opportunities to explore cancer therapies.

Emerging roles of aerobic glycolysis in breast cancer

Altered aerobic glycolysis is a well-recognized characteristic of cancer cell energy metabolism, known as the Warburg effect. Even in the presence of abundant oxygen, a majority of tumor cells produce substantial amounts of energy through a high glycolytic metabolism, and breast cancer (BC) is no exception. Breast cancer continues to be the second leading cause of cancer-associated mortality in women worldwide. However, the precise role of aerobic glycolysis in the development of BC remains elusive. Therefore, the present review attempts to address the implication of key enzymes of the aerobic glycolytic pathway including hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK), glucose transporters (GLUTs), together with related signaling pathways including protein kinase B(PI3K/AKT), mammalian target of rapamycin (mTOR) and adenosine monophosphate-activated protein kinase (AMPK) and transcription factors (c-myc, p53 and HIF-1) in the research of BC. Thus, the review of aerobic glycolysis in BC may evoke novel ideas for the BC treatment.

Molecular intricacies of aerobic glycolysis in cancer: current insights into the classic metabolic phenotype

Aerobic glycolysis is the process of oxidation of glucose into pyruvate followed by lactate production under normoxic condition. Distinctive from its anaerobic counterpart (i.e. glycolysis that occurs under hypoxia), aerobic glycolysis is frequently witnessed in cancers, popularly known as the "Warburg effect", and it is one of the earliest known evidences of metabolic alteration in neoplasms. Intracellularly, aerobic glycolysis circumvents mitochondrial oxidative phosphorylation (OxPhos), facilitating an increased rate of glucose hydrolysis. This in turn enables cancer cells to successfully compete with normal cells for glucose uptake in order to maintain uninterrupted growth. In addition, evading OxPhos mitigates excessive generation/accumulation of reactive oxygen species that otherwise may be deleterious to cells. Emerging data indicate that aerobic glycolysis in cancer also promotes glutaminolysis to satisfy the precursor requirements of certain biosynthetic processes (e.g. nucleic acids). Next, the metabolic intermediates of aerobic glycolysis also feed the pentose phosphate pathway (PPP) to facilitate macromolecular biosynthesis necessary for cancer cell growth and proliferation. Extracellularly, the extrusion of the end-product of aerobic glycolysis, i.e. lactate, alters the tumor microenvironment, and impacts cancer-associated cells. Collectively, accumulating data unequivocally demonstrate that aerobic glycolysis implicates myriad of molecular and functional processes to support cancer progression. This review, in the light of recent research, dissects the molecular intricacies of its regulation, and also deliberates the emerging paradigms to target aerobic glycolysis in cancer therapy.

Role of miRNA in the regulation of cannabidiol-mediated apoptosis in neuroblastoma cells

Neuroblastoma (NBL) is one of the most common childhood cancers that originate from the immature nerve cells of the sympathetic system. Studies with NBL cancers have also shown that miRNAs are dysregulated and may play a critical role in pathogenesis. Cannabidiol (CBD) is a non-psychoactive compound found in marijuana which has been previously shown by our laboratory and others to induce apoptosis in cancer cells. However, there are no studies reported to test if CBD mediates these effects through regulation of miRNA. In the current study, therefore, we investigated if CBD induces apoptosis in human NBL cell lines, SH SY5Y and IMR-32, and if it is regulated by miRNA. Our data demonstrated that CBD induces apoptosis in NBL cells through activation of serotonin and vanilloid receptors. We also found that caspase-2 and -3 played an important role in the induction of apoptosis. CBD also significantly reduced NBL cell migration and invasion in vitro. Furthermore, CBD blocked mitochondrial respiration and caused a shift in metabolism towards glycolysis. CBD altered the expression of miRNA specifically, down-regulating hsa-let-7a and upregulating hsa-mir-1972. Downregulation of let-7a increased expression of target caspase-3, and growth arrest specific-7 (GAS-7) genes. Upregulation of hsa-mir-1972 caused decreased expression of BCL2L1 and SIRT2 genes. Together, our studies suggest that CBD-mediated apoptosis in NBL cells is regulated by miRNA.