Sugar and fat - that's where it's at: metabolic changes in tumors

Metabolic priming by multiple enzyme systems supports glycolysis, HIF1α stabilisation, and human cancer cell survival in early hypoxia

Adaptation to chronic hypoxia occurs through changes in protein expression, which are controlled by hypoxia-inducible factor 1α (HIF1α) and are necessary for cancer cell survival. However, the mechanisms that enable cancer cells to adapt in early hypoxia, before the HIF1α-mediated transcription programme is fully established, remain poorly understood. Here we show in human breast cancer cells, that within 3 h of hypoxia exposure, glycolytic flux increases in a HIF1α-independent manner but is limited by NAD+ availability. Glycolytic ATP maintenance and cell survival in early hypoxia rely on reserve lactate dehydrogenase A capacity as well as the activity of glutamate-oxoglutarate transaminase 1 (GOT1), an enzyme that fuels malate dehydrogenase 1 (MDH1)-derived NAD+. In addition, GOT1 maintains low α-ketoglutarate levels, thereby limiting prolyl hydroxylase activity to promote HIF1α stabilisation in early hypoxia and enable robust HIF1α target gene expression in later hypoxia. Our findings reveal that, in normoxia, multiple enzyme systems maintain cells in a primed state ready to support increased glycolysis and HIF1α stabilisation upon oxygen limitation, until other adaptive processes that require more time are fully established.

Mechanisms of obesity- and diabetes mellitus-related pancreatic carcinogenesis: a comprehensive and systematic review

Research on obesity- and diabetes mellitus (DM)-related carcinogenesis has expanded exponentially since these two diseases were recognized as important risk factors for cancers. The growing interest in this area is prominently actuated by the increasing obesity and DM prevalence, which is partially responsible for the slight but constant increase in pancreatic cancer (PC) occurrence. PC is a highly lethal malignancy characterized by its insidious symptoms, delayed diagnosis, and devastating prognosis. The intricate process of obesity and DM promoting pancreatic carcinogenesis involves their local impact on the pancreas and concurrent whole-body systemic changes that are suitable for cancer initiation. The main mechanisms involved in this process include the excessive accumulation of various nutrients and metabolites promoting carcinogenesis directly while also aggravating mutagenic and carcinogenic metabolic disorders by affecting multiple pathways. Detrimental alterations in gastrointestinal and sex hormone levels and microbiome dysfunction further compromise immunometabolic regulation and contribute to the establishment of an immunosuppressive tumor microenvironment (TME) for carcinogenesis, which can be exacerbated by several crucial pathophysiological processes and TME components, such as autophagy, endoplasmic reticulum stress, oxidative stress, epithelial-mesenchymal transition, and exosome secretion. This review provides a comprehensive and critical analysis of the immunometabolic mechanisms of obesity- and DM-related pancreatic carcinogenesis and dissects how metabolic disorders impair anticancer immunity and influence pathophysiological processes to favor cancer initiation.

The Role of Reprogrammed Glucose Metabolism in Cancer

Cancer cells reprogram their metabolism to meet biosynthetic needs and to adapt to various microenvironments. Accelerated glycolysis offers proliferative benefits for malignant cells by generating glycolytic products that move into branched pathways to synthesize proteins, fatty acids, nucleotides, and lipids. Notably, reprogrammed glucose metabolism and its associated events support the hallmark features of cancer such as sustained cell proliferation, hijacked apoptosis, invasion, metastasis, and angiogenesis. Overproduced enzymes involved in the committed steps of glycolysis (hexokinase, phosphofructokinase-1, and pyruvate kinase) are promising pharmacological targets for cancer therapeutics. In this review, we summarize the role of reprogrammed glucose metabolism in cancer cells and how it can be manipulated for anti-cancer strategies.

Assessment of Serum Uric Acid, Urea, and Glucose Levels and Associated Factors among Breast Cancer Patients Attending A Tertiary Hospital in Bahirdar, Ethiopia: A Comparative Cross-Sectional Study

Background

Breast cancer is currently become a major public health problem in both developed and developing regions, it is one of the most common surgical problems in Ethiopia. Therefore, this study assessed serum uric acid, urea, and glucose levels and associated factors among benign, malignant breast cancer patients and apparently healthy women attending at Felege-Hiwot comprehensive Specialized Hospital.

Methods

Hospital based comparative cross-sectional study was conducted among benign, malignant breast cancer patients and apparently healthy women attending at Felege-Hiwot Comprehensive Specialized Hospital. Out of 178 study participants 66 benign and 23 malignant fine needle aspirate cytology confirmed breast cancer patients and 89 apparently healthy women, included. Multivariable logistic regression models used to measure the strength of associations. A P value of < 0.05 was considered statistically significant.

Results

Majority of the study participants, 81(91%) controls, 55(83.3%) benign, and 17(73.9%) malignant cases were premenopausal. Serum glucose 144.47±74.35 and uric acid 6.84±2.54 levels were significantly elevated in malignant cases than control (p-value< 0.05). Patients with malignant status were 4.38 times more likely to have hyperglycemia (AOR=4.38, 95%CI: 1.98-19.97) and 5.53 times more likely have hyperuricemia (AOR=20.43-95% CI: 6.80-61.23), 4 times more likely to have uremia (AOR=4.09, 95% CI: 1.06-15.91) compared to apparently healthy women.

Conclusion

Serum glucose, and uric acid levels were significantly higher in malignant and benign cases compared with apparently healthy women. Family history of breast cancer, body mass index, systolic hypertension, comorbidity, residence and menopausal status were significantly associated with hyperglycemia, uremia and hyperuricemia.

Preventing ovariectomy-induced weight gain decreases tumor burden in rodent models of obesity and postmenopausal breast cancer

BACKGROUND

Obesity and adult weight gain are linked to increased breast cancer risk and poorer clinical outcomes in postmenopausal women, particularly for hormone-dependent tumors. Menopause is a time when significant weight gain occurs in many women, and clinical and preclinical studies have identified menopause (or ovariectomy) as a period of vulnerability for breast cancer development and promotion.

METHODS

We hypothesized that preventing weight gain after ovariectomy (OVX) may be sufficient to prevent the formation of new tumors and decrease growth of existing mammary tumors. We tested this hypothesis in a rat model of obesity and carcinogen-induced postmenopausal mammary cancer and validated our findings in a murine xenograft model with implanted human tumors.

RESULTS

In both models, preventing weight gain after OVX significantly decreased obesity-associated tumor development and growth. Importantly, we did not induce weight loss in these animals, but simply prevented weight gain. In both lean and obese rats, preventing weight gain reduced visceral fat accumulation and associated insulin resistance. Similarly, the intervention decreased circulating tumor-promoting growth factors and inflammatory cytokines (i.e., BDNF, TNFα, FGF-2), with greater effects in obese compared to lean rats. In obese rats, preventing weight gain decreased adipocyte size, adipose tissue macrophage infiltration, reduced expression of the tumor-promoting growth factor FGF-1 in mammary adipose, and reduced phosphorylated FGFR indicating reduced FGF signaling in tumors.

CONCLUSIONS

Together, these findings suggest that the underlying mechanisms associated with the anti-tumor effects of weight maintenance are multi-factorial, and that weight maintenance during the peri-/postmenopausal period may be a viable strategy for reducing obesity-associated breast cancer risk and progression in women.

Platelet isoform of phosphofructokinase accelerates malignant features in breast cancer

The platelet isoform of phosphofructokinase (PFKP) is one of the key enzymes in the glycolytic pathway. PFKP is highly expressed in several cancers, and it has been reported to be involved in the progression of cancer cells. However, its oncological role in breast cancer (BC) remains unclear. The present study aimed to evaluate the function of PFKP in BC cells and its expression level in patients with BC. Firstly, the mRNA and protein expression of PFKP was evaluated in BC and non‑cancerous mammary cell lines. Polymerase chain reaction (PCR) array analysis was conducted to evaluate the correlation between PFKP and 84 cancer‑related genes. Then, PFKP knockdown was conducted using small interfering RNA, and cell proliferation, invasiveness and migration were analyzed. Furthermore, the association between PFKP mRNA expression and clinicopathological factors was investigated in 167 patients with BC. PFKP was highly expressed in estrogen receptor‑negative and human epidermal growth factor receptor 2‑negative BC cell lines. PCR array analysis demonstrated that the expression level of PFKP was significantly correlated with that of transforming growth factor‑β1 and MYC proto‑oncogene. PFKP knockdown significantly decreased the proliferation and invasiveness of MCF7, SK‑BR‑3, and MDA‑MB‑231 cells. Furthermore, cell migration was inhibited in SK‑BR‑3 and MDA‑MB‑231 cells. In the clinical specimens, patients with T2/T3/T4, lymph node metastasis, or stage II/III/IV exhibited higher expression of PFKP mRNA than patients with less severe disease. In conclusion, the present findings indicated that PFKP is involved in promoting tumor‑progressive oncological roles in BC cells across different subtypes and is considered a possible novel therapeutic target for BC.

Salidroside Induces Apoptosis in Human Gastric Cancer Cells via the Downregulation of ENO1/PKM2/GLUT1 Expression

Salidroside is reported to have a wide range of pharmacological properties and has been proven to play a key anti-cancer effect. This study investigated the effects of purified salidroside, an ingredient of Rhodiola rosea, on the proliferation of two human gastric cancer cell lines and further investigating its possible molecular mechanisms. We verified that salidroside exerts a dose-dependent inhibitory effect on the proliferation of SGC-7901 and MKN-45 human gastric cancer cells. Moreover, salidroside can induce cell apoptosis, which was accompanied by an increase in nuclear fragmentation. In addition, salidroside inhibited glycolysis, as evidenced by the reduced expression levels of the glycolysis-related enzymes pyruvate kinase isoenzyme M2 (PKM2), enolase 1 (ENO1) and glucose transporter 1 (GLUT1), which could play important roles in the metabolism of gastric cancer cells. Further investigation showed that salidroside exerted potent anti-proliferative effects by inhibiting glycolysis in human gastric cancer cells in vitro. In vivo, xenograft tumors treated with salidroside were significantly smaller than those in the control animals. Therefore, salidroside could be a promising therapeutic prospect in the treatment of gastric cancer.

Mutant Presenilin 1 Dysregulates Exosomal Proteome Cargo Produced by Human-Induced Pluripotent Stem Cell Neurons

The accumulation and propagation of hyperphosphorylated tau (p-Tau) is a neuropathological hallmark occurring with neurodegeneration of Alzheimer's disease (AD). Extracellular vesicles, exosomes, have been shown to initiate tau propagation in the brain. Notably, exosomes from human-induced pluripotent stem cell (iPSC) neurons expressing the AD familial A246E mutant form of presenilin 1 (mPS1) are capable of inducing tau deposits in the mouse brain after in vivo injection. To gain insights into the exosome proteome cargo that participates in propagating tau pathology, this study conducted proteomic analysis of exosomes produced by human iPSC neurons expressing A246E mPS1. Significantly, mPS1 altered the profile of exosome cargo proteins to result in (1) proteins present only in mPS1 exosomes and not in controls, (2) the absence of proteins in the mPS1 exosomes which were present only in controls, and (3) shared proteins which were upregulated or downregulated in the mPS1 exosomes compared to controls. These results show that mPS1 dysregulates the proteome cargo of exosomes to result in the acquisition of proteins involved in the extracellular matrix and protease functions, deletion of proteins involved in RNA and protein translation systems along with proteasome and related functions, combined with the upregulation and downregulation of shared proteins, including the upregulation of amyloid precursor protein. Notably, mPS1 neuron-derived exosomes displayed altered profiles of protein phosphatases and kinases involved in regulating the status of p-tau. The dysregulation of exosome cargo proteins by mPS1 may be associated with the ability of mPS1 neuron-derived exosomes to propagate tau pathology.

Serum Metabolic Profiling Identifies a Biomarker Panel for Improvement of Prostate Cancer Diagnosis

Objectives

To identify and validate a biomarker panel by serum metabolic profiling for improvement of PCa diagnosis.

Materials and Methods

Totally, 134 individuals were included in this study. Among them, 39 PCa patients and 45 control patients (negative prostate biopsy) were involved in the discovery phase and 50 healthy controls were enrolled for validation phase of metabolomics study. LC-MS Analysis was used for the identification of the serum metabolites of patients.

Results

Logistics regression analysis shows that 5 metabolites [dMePE(18:0/18:2), PC(16:0/20:2), PS(15:0/18:2), SM(d16:0/24:1], Carnitine C14:0) were significantly changed in PCa patients compared with control patients. A metabolic panel (MET) was calculated, showing a significantly higher diagnostic performance than PSA in differentiating PCa from control patients [AUC (MET vs. PSA): 0.823 ± 0.046 vs. 0.712 ± 0.057, p<0.001]. Moreover, this panel was superior to PSA in distinguishing PCa from negative prostate biopsies when PSA levels were less than 20 ng/ml [AUC (MET vs. PSA]: 0.836 ± 0.050 vs. 0.656 ± 0.067, p<0.001]. In the validation set, the MET panel yielded an AUC of 0.823 in distinguishing PCa patients from healthy controls, showing a significant improvement of PCa detection.

Conclusions

The metabolite biomarker panel discovered in this study presents a good diagnostic performance for the detection of PCa.

Epstein-Barr Virus-Encoded Latent Membrane Protein 1 and B-Cell Growth Transformation Induce Lipogenesis through Fatty Acid Synthase

Despite many attempts to develop novel therapies, EBV-specific therapies currently remain largely investigational, and EBV-associated malignancies are often associated with a worse prognosis. Therefore, there is a clear demand for EBV-specific therapies for both prevention and treatment of virus-associated malignancies.

Latent membrane protein 1 (LMP1) is the major transforming protein of Epstein-Barr virus (EBV) and is critical for EBV-induced B-cell transformation in vitro. Several B-cell malignancies are associated with latent LMP1-positive EBV infection, including Hodgkin’s and diffuse large B-cell lymphomas. We have previously reported that promotion of B cell proliferation by LMP1 coincided with an induction of aerobic glycolysis. To further examine LMP1-induced metabolic reprogramming in B cells, we ectopically expressed LMP1 in an EBV-negative Burkitt’s lymphoma (BL) cell line preceding a targeted metabolic analysis. This analysis revealed that the most significant LMP1-induced metabolic changes were to fatty acids. Significant changes to fatty acid levels were also found in primary B cells following EBV-mediated B-cell growth transformation. Ectopic expression of LMP1- and EBV-mediated B-cell growth transformation induced fatty acid synthase (FASN) and increased lipid droplet formation. FASN is a crucial lipogenic enzyme responsible for de novo biogenesis of fatty acids in transformed cells. Furthermore, inhibition of lipogenesis caused preferential killing of LMP1-expressing B cells and significantly hindered EBV immortalization of primary B cells. Finally, our investigation also found that USP2a, a ubiquitin-specific protease, is significantly increased in LMP1-positive BL cells and mediates FASN stability. Our findings demonstrate that ectopic expression of LMP1- and EBV-mediated B-cell growth transformation leads to induction of FASN, fatty acids, and lipid droplet formation, possibly pointing to a reliance on lipogenesis. Therefore, the use of lipogenesis inhibitors could be used in the treatment of LMP1⁺ EBV-associated malignancies by targeting an LMP1-specific dependency on lipogenesis.

IMPORTANCE Despite many attempts to develop novel therapies, EBV-specific therapies currently remain largely investigational, and EBV-associated malignancies are often associated with a worse prognosis. Therefore, there is a clear demand for EBV-specific therapies for both prevention and treatment of virus-associated malignancies. Noncancerous cells preferentially obtain fatty acids from dietary sources, whereas cancer cells will often produce fatty acids themselves by de novo lipogenesis, often becoming dependent on the pathway for cell survival and proliferation. LMP1- and EBV-mediated B-cell growth transformation leads to induction of FASN, a key enzyme responsible for the catalysis of endogenous fatty acids. Preferential killing of LMP1-expressing B cells following inhibition of FASN suggests that targeting LMP-induced lipogenesis is an effective strategy in treating LMP1-positive EBV-associated malignancies. Importantly, targeting unique metabolic perturbations induced by EBV could be a way to explicitly target EBV-positive malignancies and distinguish their treatment from EBV-negative counterparts.

Doxorubicin Inhibits Phosphatidylserine Decarboxylase and Modifies Mitochondrial Membrane Composition in HeLa Cells

Doxorubicin (DXR) is a drug widely used in chemotherapy. Its mode of action is based on its intercalation properties, involving the inhibition of topoisomerase II. However, few studies have reported the mitochondrial effects of DXR while investigating cardiac toxicity induced by the treatment, mostly in pediatric cases. Here, we demonstrate that DXR alters the mitochondrial membrane composition associated with bioenergetic impairment and cell death in human cancer cells. The remodeling of the mitochondrial membrane was explained by phosphatidylserine decarboxylase (PSD) inhibition by DXR. PSD catalyzes phosphatidylethanolamine (PE) synthesis from phosphatidylserine (PS), and DXR altered the PS/PE ratio in the mitochondrial membrane. Moreover, we observed that DXR localized to the mitochondrial compartment and drug uptake was rapid. Evaluation of other topoisomerase II inhibitors did not show any impact on the mitochondrial membrane composition, indicating that the DXR effect was specific. Therefore, our findings revealed a side molecular target for DXR and PSD, potentially involved in DXR anti-cancer properties and the associated toxicity.

Betaherpesvirus assembly and egress: Recent advances illuminate the path

The human betaherpesviruses, human cytomegalovirus (HCMV; species Human betaherpesvirus 5) and human herpesviruses 6A, 6B, and 7 (HHV-6A, -6B, and -7; species Human betaherpesviruses 6A, 6B, and 7) are highly prevalent and can cause severe disease in immune-compromised and immune-naive populations in well- and under-developed communities. Herpesvirus virion assembly is an intricate process that requires viral orchestration of host systems. In this review, we describe recent advances in some of the many cellular events relevant to assembly and egress of betaherpesvirus virions. These include modifications of host metabolic, immune, and autophagic/recycling systems. In addition, we discuss unique aspects of betaherpesvirus virion structure, virion assembly, and the cellular pathways employed during virion egress.

Gene and Biochemical Pathway Evaluation of Burns Injury via Protein-Protein Interaction Network Analysis

Background:

Severe burns injury can affect several vital systems in the body and can cause inflammation in organs such as the heart, liver, and kidney. Many inflammatory mediators and regulatory hormones related to burn injuries are recognized. In this study, the genes related to burn injury interacted via network analysis, and the central nodes were enriched through gene ontology (GO).

Materials and Methods:

Disease query of STRING database was used for data gathering, and the network was constructed using Cytoscape software version 3.6.0. After gene screening, the central nodes were enriched via GO analysis by ClueGO. The highlighted genes and pathways were clustered and analyzed in detail.

Results:

Among 1067 genes, 35 critical genes that are involved in the 14 highlighted biochemical pathways were recognized. Interpretation of the finding indicates that a number of central genes can be considered as potential biomarkers related to burn injury.

Conclusion:

Can we revise to "Burn injuries have features that are common to several diseases and increases their risk.

AKT-dependent sugar addiction by benzyl isothiocyanate in breast cancer cells

The overall promise of breast cancer chemoprevention is exemplified by clinical success of selective estrogen receptor modulators and aromatase inhibitors. Despite clinical efficacy, these interventions have limitations, including rare but serious side effects and lack of activity against estrogen receptor-negative breast cancers. We have shown previously that dietary administration of benzyl isothiocyanate (BITC), which occurs naturally as a thioglucoside conjugate in edible cruciferous vegetables, inhibits development of estrogen receptor-negative breast cancer in mouse mammary tumor virus-neu (MMTV-neu) transgenic mice. This study demonstrates AKT-mediated sugar addiction in breast cancer chemoprevention by BITC. BITC-treated MMTV-neu mice exhibited increased 2-deoxy-2-(¹⁸ F)-fluoro-D-glucose (¹⁸ F-FDG) uptake in mammary tumors in vivo in comparison with mice fed basal diet. Cellular studies using MDA-MB-231 and SUM159 human breast cancer cell lines revealed BITC-mediated induction and punctate localization of glucose transporter GLUT-1, which was accompanied by an increase in intracellular pyruvate levels. BITC treatment resulted in increased S⁴⁷³ phosphorylation (activation) of AKT in cells in vitro as well as in mammary tumors of MMTV-neu mice in vivo. Increased glucose uptake, punctate pattern of GLUT-1 localization, and intracellular pyruvate levels resulting from BITC exposure were significantly attenuated in the presence of a pharmacological inhibitor of AKT (MK-2206). Inhibition of AKT augmented BITC-mediated inhibition of cell migration and colony formation. BITC-induced apoptotic cell death was also increased by pharmacological inhibition of AKT. These results indicate increased glucose uptake/metabolism by BITC treatment in breast cancer cells suggesting that breast cancer chemoprevention by BITC may be augmented by pharmacological inhibition of AKT.

Preoperative fasting hyperglycemia is an independent prognostic factor for postoperative survival after gallbladder carcinoma radical surgery

BACKGROUND

Preoperative high blood glucose levels are closely associated with poor performance and high mortality in cancer patients. This study was designed to investigate the relationship between preoperative fasting hyperglycemia and the prognosis of patients with gallbladder cancer (GBC) after undergoing GBC radical surgery.

PATIENTS AND METHODS

A retrospective analysis of 83 eligible patients who underwent GBC radical surgery between 2007 and 2016 was performed. Factors affecting overall survival (OS) and recurrence-free survival (RFS) were analyzed by univariate and multivariate analyses.

RESULTS

Of the 83 patients, 35 (42.2%) had preoperative fasting hyperglycemia. The median OS of the enrolled patients was 12 months. The median OS in patients with fasting hyperglycemia before surgery was 18 months, which was shorter than for patients with normal fasting blood glucose levels before surgery (47 months, P<0.001). Preoperative fasting hyperglycemia was associated with shorter survival times in univariate analyses (HR, 3.215; 95% CI, 1.846-5.601; P<0.001). Multivariate analysis showed that patients with preoperative fasting hyperglycemia had a lower OS (HR, 2.832; 95% CI, 1.480-5.418; P=0.002) and RFS (HR, 2.051; 95% CI, 1.127-3.733; P=0.019) than patients with normal preoperative fasting blood glucose levels.

CONCLUSION

Preoperative fasting hyperglycemia is an independent indicator of poor prognosis in GBC patients after GBC radical surgery.

Quercetin suppresses the mobility of breast cancer by suppressing glycolysis through Akt-mTOR pathway mediated autophagy induction

Tumor metastasis is the primary factor causing death of cancer patients and it is a study emphasis in cancer treatment to suppress tumor metastasis by inhibiting glycolysis, which is the main way of energy supply for cell mobility in tumor. In the present study, we aimed to explore the effect of quercetin, a bioactive flavonoid, on tumor metastasis and cell glycolysis and its related functionary mechanism in breast cancer progression. Firstly, trans-well invasion assay and wound healing assay indicated that quercetin effectively suppressed cell mobility. The corresponding western blot revealed that quercetin treatment down-regulated the expression of cell migration marker proteins, such as matrix metalloproteinase 2 (MMP-2), MMP-9 and vascular endothelial growth factor (VEGF). The further experiments exhibited that quercetin successfully blocked cell glycolysis by inhibiting the level of glucose uptake and the production of lactic acid, and also decreased the level of glycolysis-related proteins Pyruvate kinase M2 (PKM2), Glucose transporter1(GLUT1) and Lactate dehydrogenase A (LDHA). The above results revealed that quercetin might inhibit glycolysis to limit the migration of tumor cells by reducing the acidity of the tumor microenvironment. Moreover, our further investigation showed that quercetin induced obvious autophagy via inactivating the Akt-mTOR pathway. At the same time, the application of autophagy inhibitor 3-MA and Akt-mTOR pathway inducer IGF-1 further demonstrated that quercetin exerted inhibiting effect on cell mobility and glycolysis through Akt-mTOR pathway mediated autophagy induction. At last, the in vivo experiments also showed that quercetin treatment could suppress tumor growth and metastasis, inhibit glycolysis and induce autophagy through the inhibition of p-AKT/AKT. Taken together, we firstly revealed that quercetin suppressed the progression of breast cancer by inhibiting cell mobility and glycolysis through Akt-mTOR pathway mediated autophagy induction and may provide a potential therapeutic target for breast cancer treatment.

Fatty acid metabolism in breast cancer subtypes

Dysregulation of fatty acid metabolism is recognized as a component of malignant transformation in many different cancers, including breast; yet the potential for targeting this pathway for prevention and/or treatment of cancer remains unrealized. Evidence indicates that proteins involved in both synthesis and oxidation of fatty acids play a pivotal role in the proliferation, migration and invasion of breast cancer cells. The following essay summarizes data implicating specific fatty acid metabolic enzymes in the genesis and progression of breast cancer, and further categorizes the relevance of specific metabolic pathways to individual intrinsic molecular subtypes of breast cancer. Based on mRNA expression data, the less aggressive luminal subtypes appear to rely on a balance between de novo fatty acid synthesis and oxidation as sources for both biomass and energy requirements, while basal-like, receptor negative subtypes overexpress genes involved in the utilization of exogenous fatty acids. With these differences in mind, treatments may need to be tailored to individual subtypes.

Metformin Targets Glucose Metabolism in Triple Negative Breast Cancer

Metformin is the most widely administered anti-diabetic agent worldwide. In patients receiving metformin for metabolic syndrome or diabetes, it reduces the incidence and improves the survival of breast cancer (BC) patients. We have previously shown that metformin is particularly potent against triple negative breast cancer (TNBC), with a reduction of proliferation, oncogenicity and motility, inhibition of pro-oncogenic signaling pathways and induction of apoptosis. These BCs are well recognized to be highly dependent on glucose/glucosamine (metabolized through anaerobic glycolysis) and lipids, which are metabolized for the production of energy and cellular building blocks to sustain a high rate of proliferation. We have previously demonstrated that metformin inhibits lipid metabolism, specifically targeting fatty acid synthase (FASN), cholesterol biosynthesis and GM1 lipid rafts in TNBC. We also reported that glucose promotes phenotypic aggression and reduces metformin efficacy. We now show that metformin inhibits several key enzymes requisite to glucose metabolism in TNBC, providing additional insight into why metformin is especially toxic to this subtype of BC. Our data suggests that the use of metformin to target key metabolic defects in lipid and carbohydrate metabolism in cancer may be broadly applicable, especially against highly aggressive malignant cells.

Docosahexaenoic acid reduces sterol regulatory element binding protein-1 and fatty acid synthase expression and inhibits cell proliferation by inhibiting pAkt signaling in a human breast cancer MCF-7 cell line

Background

Fatty acid synthase (FASN), the major enzyme in de novo fatty acid synthesis, is highly expressed in breast cancer and its expression is reduced by polyunsaturated fatty acids (PUFAs) in liver. We previously found a positive association between rat mammary tumor levels of the n-6 PUFA arachidonic acid (AA) and tumor weight. We examined the roles of the major n-3 PUFA, docosahexaenoic acid (DHA, 22:6n-3), and the major n-6 PUFA, AA, in FASN expression in, and proliferation of, human breast cancer MCF-7 cells.

Methods

The cells were treated for 48 h with BSA or 60 μM BSA-bound DHA, AA, or oleic acid (OA, 18:1n-9), then were incubated with or without estradiol or insulin. Western blot and ³H–thymidine incorporation assay were used to determine the role of DHA on FASN regulation and MCF-7 cell proliferation.

Results

DHA, but neither AA nor OA, inhibits estradiol-induced and insulin-induced expression of the precursor of sterol regulatory element binding protein-1 (p-SREBP-1), its mature form (m-SREBP-1), and FASN. Estradiol or insulin stimulation increased the pAkt/Akt and pS6/S6 ratios, expression of p-SREBP-1, m-SREBP-1, and FASN, and cell proliferation, and these effects were decreased by DHA. The DHA-induced decrease in FASN expression resulted from reduced pAkt/Akt signaling and not pERK1/2/ERK1/2 signaling. In addition, DHA enhanced the inhibitory effect of LY294002 on pAkt signaling and expression of p-SREBP-1, m-SREBP-1, and FASN. However, addition of rapamycin, an inhibitor of the mTOR signaling pathways, 1 h before addition of estradiol or insulin increased the pAkt/Akt ratio and FASN expression, and this effect was inhibited by addition of DHA 48 h before rapamycin.

Conclusion

We conclude that, in MCF-7 cells, DHA inhibits pAKT signaling and thus expression of p-SREBP-1, m-SREBP-1, and FASN and cell proliferation.

Proteomics and metabolomics identify molecular mechanisms of aging potentially predisposing for chronic lymphocytic leukemia

B cell chronic lymphocytic leukemia (B-CLL), the most common type of leukemia in adults, is still essentially incurable despite the development of novel therapeutic strategies. This reflects the incomplete understanding of the pathophysiology of this disease. A comprehensive proteome analysis of primary human B-CLL cells and B cells from younger as well as elderly healthy donors was performed. For comparison, the chronic B cell leukemia cell line JVM-13 was also included. A principal component analysis comprising 6,945 proteins separated these four groups, placing B cells of aged-matched controls between those of young donors and B-CLL patients, while identifying JVM-13 as poorly related cells. Mass spectrometric proteomics data have been made fully accessible via ProteomeXchange with identifier PXD006570-PXD006572, PXD006576, PXD006578, and PXD006589-PXD006591. Remarkably, B cells from aged controls displayed significant regulation of proteins related to stress management in mitochondria and ROS stress such as DLAT, FIS1, and NDUFAB1, and DNA repair, including RAD9A, MGMT, and XPA. ROS levels were indeed found significantly increased in B cells but not in T cells or monocytes from aged individuals. These alterations may be relevant for tumorigenesis and were observed similarly in B-CLL cells. In B-CLL cells, some remarkable unique features like the loss of tumor suppressor molecules PNN and JARID2, the stress-related serotonin transporter SLC6A4, and high expression of ZNF207, CCDC88A, PIGR and ID3, otherwise associated with stem cell phenotype, were determined. Alterations of metabolic enzymes were another outstanding feature in comparison to normal B cells, indicating increased beta-oxidation of fatty acids and increased consumption of glutamine. Targeted metabolomics assays corroborated these results. The present findings identify a potential proteome signature for immune senescence in addition to previously unrecognized features of B-CLL cells and suggest that aging may be accompanied by cellular reprogramming functionally relevant for predisposing B cells to transform to B-CLL cells.

Serotonin Analogues as Inhibitors of Breast Cancer Cell Growth

Serotonin (5-hydroxytryptamine, 5-HT) is a critical local regulator of epithelial homeostasis in the breast and exerts its actions through a number of receptors. Dysregulation of serotonin signaling is reported to contribute to breast cancer pathophysiology by enhancing cell proliferation and promoting resistance to apoptosis. Preliminary analyses indicated that the potent 5-HT1B/1D serotonin receptor agonist 5-nonyloxytryptamine (5-NT), a triptan-like molecule, induced cell death in breast cancer cell lines. Thus, we synthesized a series of novel alkyloxytryptamine analogues, several of which decreased the viability of various human cancer cell lines. Proteomic and metabolomic analyses showed that compounds 6 and 10 induced apoptosis and interfered with signaling pathways that regulate protein translation and survival, such as the Akt/mTOR pathway, in triple-negative breast cancer cells.

Differential Proteome Analysis of Extracellular Vesicles from Breast Cancer Cell Lines by Chaperone Affinity Enrichment

The complexity of human tissue fluid precludes timely identification of cancer biomarkers by immunoassay or mass spectrometry. An increasingly attractive strategy is to primarily enrich extracellular vesicles (EVs) released from cancer cells in an accelerated manner compared to normal cells. The Vn96 peptide was herein employed to recover a subset of EVs released into the media from cellular models of breast cancer. Vn96 has affinity for heat shock proteins (HSPs) decorating the surface of EVs. Reflecting their cells of origin, cancer EVs displayed discrete differences from those of normal phenotype. GELFrEE LC/MS identified an extensive proteome from all three sources of EVs, the vast majority having been previously reported in the ExoCarta database. Pathway analysis of the Vn96-affinity proteome unequivocally distinguished EVs from tumorigenic cell lines (SKBR3 and MCF-7) relative to a non-tumorigenic source (MCF-10a), particularly with regard to altered metabolic enzymes, signaling, and chaperone proteins. The protein data sets provide valuable information from material shed by cultured cells. It is probable that a vast amount of biomarker identities may be collected from established and primary cell cultures using the approaches described here.

Reduced production and uptake of lactate are essential for the ability of WNT5A signaling to inhibit breast cancer cell migration and invasion

Here we investigated the impact of WNT5A signaling on aerobic glycolysis and evaluated its effects on breast cancer cell migration/invasion. WNT5A signaling reduced migration and lactate production and caused selective down-regulation of the glycolytic enzyme phosphofructokinase platelet-type (PFKP). These events occurred in parallel with a WNT5A-induced inhibition of β-catenin signaling. Support for essential involvement of β-catenin and PFKP in lactate production and migration/invasion was obtained by siRNA knockdown of their expression. To also explore the effect of non-tumor cell-derived lactate, we added exogenous lactate to the cells and noted an increase in migration that was significantly impaired by recombinant WNT5A in parallel with a down-regulation of the lactate transporter monocarboxylate transporter 1 (MCT1). Interestingly enough, the drug-candidate Foxy5 (WNT5A-mimic hexapeptide) also inhibited breast cancer cell migration in the presence of exogenous lactate, suggesting a therapeutic potential for Foxy5 in managing breast tumors with high glycolytic activity. Overall, we demonstrated that WNT5A signaling (via a β-catenin-PFKP axis) reduces lactate production and lowers the expression of MCT1, a carrier mediating the uptake of lactate from the tumor microenvironment. These effects of WNT5A are essential for its ability to impair breast cancer migration/invasion even in an environment with elevated lactate levels.

Hyperglycemia, tumorigenesis, and chronic inflammation

Hyperglycemia is the most prominent sign that characterizes diabetes. Hyperglycemia favors malignant cell growth by providing energy to cancer cells. Clinical studies also showed an increased risk of diabetes being associated with different types of cancers. In addition, poorly regulated glucose metabolism in diabetic patients is often found with increased levels of chronic inflammatory markers, e.g., interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, and emerging evidence has highlighted activation of the immune response in the progression and development of cancer cells. Therefore, uncontrolled proinflammatory responses could conceivably create a chronic inflammatory state, promoting a tumor-favorable microenvironment and potentially triggering immune overactivation and cancer growth. To further understand how hyperglycemia contributes to immune overactivation, the tumor microenvironment and the development of chronic inflammation-associated tumors may provide insights into tumor biology and immunology. This paper provides a brief introduction to hyperglycemia-associated diseases, followed by a comprehensive overview of the current findings of regulatory molecular mechanisms of glycosylation on proteoglycans in the extracellular matrix under hyperglycemic conditions. Then, the authors discuss the role of hyperglycemia in tumorigenesis (particularly in prostate, liver, colorectal, and pancreatic cancers), as well as the contribution of hyperglycemia to chronic inflammation. The authors end with a brief discussion on the future perspectives of hyperglycemia/tumorigenesis and potential applications of alternative/effective therapeutic strategies for hyperglycemia-associated cancers.

Photoinduced Mild Hyperthermia and Synergistic Chemotherapy by One-Pot-Synthesized Docetaxel-Loaded Poly(lactic-co-glycolic acid)/Polypyrrole Nanocomposites

Mild hyperthermia has shown great advantages when combined with chemotherapy. The development of a multifunctional platform for the integration of mild hyperthermia capability into a drug-loading system is a key issue for cancer multimodality treatment application. Herein, a facile one-pot in situ fabrication protocol of docetaxel (DTX)-loaded poly(lactic-co-glycolic acid) (PLGA)/polypyrrole (PPy) nanocomposites was developed. While the PLGA nanoparticles (NPs) allow efficient drug loading, the PPy nanobulges embedded within the surface of the PLGA NPs, formed by in situ pyrrole polymerization without the introduction of other template agents, can act as ideal mediators for photoinduced mild hyperthermia. Physiochemical characterizations of the as-prepared nanocomposites, including structure, morphology, photothermal effects, and an in vitro drug release profile, were systematically investigated. Further, 2-deoxyglucose-terminated poly(ethylene glycol) (PEG) was anchored onto the surface of the nanocomposites to endow the nanoplatform with targeting ability to tumor cells, which resulted in a 17-fold increase of NP internalization within human breast cancer cells (MCF-7) as competed with PEG-modified nanocomposites. Mild hyperthermia can be successfully mediated by the nanoplatform, and the temperature can be conveniently controlled by careful modulation of the PPy contents within the nanocomposites or the laser power density. Importantly, we have demonstrated that MCF-7 cells, which are markedly resistant to heat treatment of traditional water-bath hyperthermia, became sensitive to the PLGA/PPy nanocomposite-mediated photothermal therapy under the same mild-temperature hyperthermia. Moreover, DTX-loaded PLGA/PPy-nanocomposite-induced mild hyperthermia can strongly enhance drug cytotoxicity to MCF-7 cells. Under the same thermal dose, photoinduced hyperthermia can convert the interaction between hyperthermia and drug treatment from interference to synergism. This is the first report on the one-pot synthesis of PLGA/PPy nanocomposites by in situ pyrrole polymerization, and such a multifunctional nanoplatform is demonstrated as a high-potential agent for photoinduced mild hyperthermia and enhanced chemotherapy.

Diagnostic roles of MUC1 and GLUT1 in differentiating thymic carcinoma from type B3 thymoma

MUC1 is a transmembrane mucin that has been related to tumor progression and outcome in various malignancies. GLUT1 is a member of the mammalian facilitative glucose transporter (GLUT) family of passive carriers that functions as an energy-independent system for transporting glucose. Both of them are useful markers for the diagnosis, progression, and prognosis of various tumors, especially those that are cancerous. However, the clinical significance of MUC1 and GLUT1 in thymic epithelial tumors remains uncertain due to a lack of quality specimen and studies at sufficient scale, both owing, in part, to the rarity of the tumors. The aim of this article is to study the expression patterns of MUC1 and GLUT1 in thymic carcinoma and type B3 thymoma, and to evaluate their diagnostic value for these two types of tumors via immunohistochemistry. Forty-three patients were included in the study, including twenty-two with thymic carcinoma and twenty-one with type B3 thymoma. Tumor tissue sections were immunohistochemically stained for MUC1 and GLUT1; meanwhile, some tumors were also stained with CKpan, TDT, CD5, and CD117. MUC1 was expressed in a total of 17 cases, with a positive rate of 77.27% (17/22) in thymic carcinoma and 9.52% (2/21) in type B3 thymoma, revealing a significant difference (p<0.0001). A significant difference (p<0.0001) was also shown for GLUT1, where the positive rates for thymic carcinoma and type B3 thymoma were 100% (22/22) and 42.86% (9/21), respectively. The expression of MUC1 was significantly correlated with GLUT1 (p<0.0001). Furthermore, GLUT1 staining sensitivity and specificity for thymic carcinoma were 100% (22/22) and 70.97% (22/31), respectively, while MUC1 staining sensitivity and specificity were 77.27% (17/22) and 89.47% (17/19), respectively. In conclusion, our study shows that MUC1 and GLUT1 staining may play a useful role in differentiating thymic carcinoma from type B3 thymoma, with high sensitivity and specificity.

Changes in the in vitro activity of platinum drugs when administered in two aliquots

BACKGROUND

The management of ovarian cancer remains a challenge. Because of the lack of early symptoms, it is often diagnosed at a late stage when it is likely to have metastasized beyond ovaries. Currently, platinum based chemotherapy is the primary treatment for the disease. However acquired drug resistance remains an on-going problem. As cisplatin brings about apoptosis by intrinsic and extrinsic pathways, this study aimed to determine changes in activity of platinum drugs when administered in two aliquots as against a bolus and sought to determine association with changes in GSH, speciation of platinum drugs and changes in protein expression.

METHODS

The efficacy of administering cisplatin, carboplatin and oxaliplatin in two aliquots with a time gap was investigated in ovarian A2780, A2780(cisR), A2780(ZD0473R) and SKOV-3 cell lines. The cellular accumulation of platinum, level of platinum - DNA binding and cellular glutathione level were determined, and proteomic studies were carried out to identify key proteins associated with platinum resistance in ovarian A2780(cisR) cancer cell line.

RESULTS

Much greater cell kill was observed with solutions left standing at room temperature than with freshly prepared solutions, indicating that the increase in activity on ageing was related to speciation of the drug in solution. Proteomic studies identified 72 proteins that were differentially expressed in A2780 and A2780(cisR) cell lines; 22 of them were restored back to normal levels as a result of synergistic treatments, indicating their relevance in enhanced drug action.

CONCLUSIONS

The proteins identified are relevant to several different cellular functions including invasion and metastasis, cell cycle regulation and proliferation, metabolic and biosynthesis processes, stress-related proteins and molecular chaperones, mRNA processing, cellular organization/cytoskeleton, cellular communication and signal transduction. This highlights the multifactorial nature of platinum resistance in which many different proteins with diverse functions play key roles. This means multiple strategies can be harnessed to overcome platinum resistance in ovarian cancer. The results of the studies can be significant both from fundamental and clinical view points.

Prolyl hydroxylase mediated inhibition of fatty acid synthase to combat tumor growth in mammary gland carcinoma

Cancer is a group of cells which grow in an uncontrolled manner and invades to the adjacent organs to form malignant tumors. Tumor hypoxia results due to contrast between the cellular oxygen expenditure and oxygen supply to the cells. Hypoxia inducible factor (HIF) is a heterodimeric transcription factor encompass of oxygen sensitive α subunit and constitutively expressed β subunit both of which are basic helix-loop-helix protein. The stability of HIF is primarily regulated by post translational prolyl hydroxylation, catalyzed by prolyl hydroxylase 2 (Phd-2). Phd-2 is a group of enzymes that acts as an oxygen sensor. Cancer cells have altered metabolism as they fulfil their energy needs through glycolysis and lipid biogenesis. HIF-1α is known to upregulate glycolysis by activating the transcription of enzymes on the glycolytic pathway and through lipogenesis. Cancer cells have over expressed fatty acid synthase owing to altered glycolytic pathway. Considering the above, it is hypothesized that chemical activation of Phd-2 can curtail down HIF-1α and subsequently fatty acid synthase expression.

Resveratrol-Related Polymethoxystilbene Glycosides: Synthesis, Antiproliferative Activity, and Glycosidase Inhibition

A small library of polymethoxystilbene glycosides (20-25) related to the natural polyphenol resveratrol have been synthesized and subjected, together with their aglycones 17-19, to an antiproliferative activity bioassay toward Caco-2 and SH-SY5Y cancer cells. Six of the compounds exhibit antiproliferative activity against at least one cell line. In particular, compounds 17 and 18 proved highly active on at least one of the two cell cultures. Compound 18 showed a GI50 value of 3 μM against Caco-2 cells, a value comparable to that of the anticancer drug 5-fluorouracil. The closely related compound 19 proved inactive, and its conjugates 22 and 25 showed weak cell growth inhibition. The results indicate that minimal differences in the structure of both polymethoxystilbenes and their glycosides can substantially affect the antiproliferative activity. The possible hydrolytic release of the aglycones 17-19 by β-glucosidase or β-galactosidase was also evaluated. Compounds 20-25 were also tested as potential β-glucosidase, β-galactosidase, and α-glucosidase inhibitors. A promising inhibitory activity toward α-glucosidase was observed for 21 (IC50 = 78 μM) and 25 (IC50 = 70 μM), which might be indicative of their potential as lead compounds for development of antidiabetic or antiobesity agents.

Antitumor effects of a drug combination targeting glycolysis, glutaminolysis and de novo synthesis of fatty acids

There is a strong rationale for targeting the metabolic alterations of cancer cells. The most studied of these are the higher rates of glycolysis, glutaminolysis and de novo synthesis of fatty acids (FAs). Despite the availability of pharmacological inhibitors of these pathways, no preclinical studies targeting them simultaneously have been performed. In the present study it was determined whether three key enzymes for glycolysis, glutaminolysis and de novo synthesis of FAs, hexokinase-2, glutaminase and fatty acid synthase, respectively, were overexpressed as compared to primary fibroblasts. In addition, we showed that at clinically relevant concentrations lonidamine, 6-diazo-5-oxo-L-norleucine and orlistat, known inhibitors of the mentioned enzymes, exerted a cell viability inhibitory effect. Genetic downregulation of the three enzymes also reduced cell viability. The three drugs were highly synergistic when administered as a triple combination. Of note, the cytotoxicity of the triple combination was low in primary fibroblasts and was well tolerated when administered into healthy BALB/c mice. The results suggest the feasibility and potential clinical utility of the triple metabolic targeting which merits to be further studied by using either repositioned old drugs or newer, more selective inhibitors.

Metabolic reprogramming and dysregulated metabolism: cause, consequence and/or enabler of environmental carcinogenesis?

Environmental contributions to cancer development are widely accepted, but only a fraction of all pertinent exposures have probably been identified. Traditional toxicological approaches to the problem have largely focused on the effects of individual agents at singular endpoints. As such, they have incompletely addressed both the pro-carcinogenic contributions of environmentally relevant low-dose chemical mixtures and the fact that exposures can influence multiple cancer-associated endpoints over varying timescales. Of these endpoints, dysregulated metabolism is one of the most common and recognizable features of cancer, but its specific roles in exposure-associated cancer development remain poorly understood. Most studies have focused on discrete aspects of cancer metabolism and have incompletely considered both its dynamic integrated nature and the complex controlling influences of substrate availability, external trophic signals and environmental conditions. Emerging high throughput approaches to environmental risk assessment also do not directly address the metabolic causes or consequences of changes in gene expression. As such, there is a compelling need to establish common or complementary frameworks for further exploration that experimentally and conceptually consider the gestalt of cancer metabolism and its causal relationships to both carcinogenesis and the development of other cancer hallmarks. A literature review to identify environmentally relevant exposures unambiguously linked to both cancer development and dysregulated metabolism suggests major gaps in our understanding of exposure-associated carcinogenesis and metabolic reprogramming. Although limited evidence exists to support primary causal roles for metabolism in carcinogenesis, the universality of altered cancer metabolism underscores its fundamental biological importance, and multiple pleiomorphic, even dichotomous, roles for metabolism in promoting, antagonizing or otherwise enabling the development and selection of cancer are suggested.

Mitochondrial biology, targets, and drug delivery

In recent years, mitochondrial medicine has emerged as a new discipline resting at the intersection of mitochondrial biology, pathology, and pharmaceutics. The central role of mitochondria in critical cellular processes such as metabolism and apoptosis has placed mitochondria at the forefront of cell science. Advances in mitochondrial biology have revealed that these organelles continually undergo fusion and fission while functioning independently and in complex cellular networks, establishing direct membrane contacts with each other and with other organelles. Understanding the diverse cellular functions of mitochondria has contributed to understanding mitochondrial dysfunction in disease states. Polyplasmy and heteroplasmy contribute to mitochondrial phenotypes and associated dysfunction. Residing at the center of cell biology, cellular functions, and disease pathology and being laden with receptors and targets, mitochondria are beacons for pharmaceutical modification. This review presents the current state of mitochondrial medicine with a focus on mitochondrial function, dysfunction, and common disease; mitochondrial receptors, targets, and substrates; and mitochondrial drug design and drug delivery with a focus on the application of nanotechnology to mitochondrial medicine. Mitochondrial medicine is at the precipice of clinical translation; the objective of this review is to aid in the advancement of mitochondrial medicine from infancy to application.

Phosphoglycerate kinase-1 is a predictor of poor survival and a novel prognostic biomarker of chemoresistance to paclitaxel treatment in breast cancer

Background:

Phosphoglycerate kinase-1 (PGK1) has been recently documented in various malignancies; however, the molecular mechanisms of the variable PGK1 expression and its clinical significance in terms of survival status remain unclear.

Methods:

Real-time quantitative PCR (real-time qPCR) and western blotting were used to verify PGK1 expression in 46 fresh breast cancer tissues and matched normal tissues. A tissue microarray (TMA) comprising 401 breast cancer tissues and 123 matched normal tissues was investigated by immunohistochemistry for PGK1 expression. Then, the correlation between PGK1 expression and the clinicopathologic features was analysed.

Results:

PGK1 mRNA and protein expression were significantly increased in breast cancer tissues compared with that in normal breast tissues. High PGK1 expression was significantly associated with higher histologic grade (P=0.009) and positive status of ER (P=0.004), Her-2 (P=0.026) and P53 (P=0.012). High levels of PGK1 expression were associated with worse overall survival (OS, P=0.02). Furthermore, patients who underwent paclitaxel chemotherapy with high levels PGK1 expression had shorter OS than did those with low levels of PGK1 expression (P<0.001). Multivariate analysis indicated that PGK1 (P=0.001) was an independent predictor in the patients treated with paclitaxel.

Conclusions:

PGK1 is a prognostic biomarker of chemoresistance to paclitaxel treatment in breast cancer.

Knockdown of the AKT3 (PKBγ), PI3KCA, and VEGFR2 genes by RNA interference suppresses glioblastoma multiforme T98G cells invasiveness in vitro

Glioblastoma multiforme (GBM) is the most common primary brain malignancy, having a very poor prognosis and is characterized by extensive brain invasion as well as resistance to the therapy. The phosphoinositide 3-kinase (PI3K)/Akt/PTEN signaling pathway is deregulated in GBM. Besides, florid vascularization and aberrantly elevated vascular endothelial growth factor (VEGF) occur very often. The present study was designed to examine the inhibitory effect of AKT3, PI3KCA, and VEGFR2 small interfering RNAs (siRNAs) on GBM cell invasiveness. T98G cells were transfected with AKT3, PI3KCA, and/or VEGFR2 siRNAs. VEGFR2 protein-positive cells were identified by flow cytometry using specific monoclonal anti-VEGFR2 antibodies. Alterations in messenger RNA (mRNA) expression of VEGF, VEGFR2, matrix metalloproteinases (MMPs) (MMP-2, MMP-9, MMP-13, MMP-14), tissue inhibitors of metalloproteinases (TIMPs) (TIMP-1, TIMP-3), c-Fos, c-Jun, hypoxia-inducible factor-1α (HIF-1α), ObRa, and cathepsin D genes were analyzed by qRT-PCR. Cells treated with specific siRNA were also analyzed for invasion using the Matrigel invasion assay. We have found significantly lower mRNA levels of MMPs, cathepsin D, VEGF, VEGFR2, HIF-1α, and c-Fos/c-Jun ratio, as well as significantly higher mRNA level of TIMPs in AKT3 and PI3KCA siRNA transfected cells compared to untransfected cells, while significantly lower mRNA levels of MMPs (MMP-2, MMP-9, MMP-14) and TIMP-1, as well as significantly higher mRNA level of TIMP-3, were shown only in cells transfected with VEGFR2 siRNA. The positive correlation between MMP-13 and ObRa mRNA copy number has been found. Summarizing, transfection of T98G cells with AKT3, PI3KCA, or VEGFR2 siRNAs leads to a significant reduction in cell invasiveness. The siRNA-induced AKT3, PI3KCA, and VEGFR2 mRNA knockdown may offer a novel therapeutic strategy to reduce the invasiveness of GBM cells.

Resveratrol enhances palmitate-induced ER stress and apoptosis in cancer cells

Background

Palmitate, a saturated fatty acid (FA), is known to induce toxicity and cell death in various types of cells. Resveratrol (RSV) is able to prevent pathogenesis and/or decelerate the progression of a variety of diseases. Several in vitro and in vivo studies have also shown a protective effect of RSV on fat accumulation induced by FAs. Additionally, endoplasmic reticulum (ER) stress has recently been linked to cellular adipogenic responses. To address the hypothesis that the RSV effect on excessive fat accumulation promoted by elevated saturated FAs could be partially mediated by a reduction of ER stress, we studied the RSV action on experimentally induced ER stress using palmitate in several cancer cell lines.

Principal Findings

We show that, unexpectedly, RSV promotes an amplification of palmitate toxicity and cell death and that this mechanism is likely due to a perturbation of palmitate accumulation in the triglyceride form and to a less important membrane fluidity variation. Additionally, RSV decreases radical oxygen species (ROS) generation in palmitate-treated cells but leads to enhanced X-box binding protein-1 (XBP1) splicing and C/EBP homologous protein (CHOP) expression. These molecular effects are induced simultaneously to caspase-3 cleavage, suggesting that RSV promotes palmitate lipoapoptosis primarily through an ER stress-dependent mechanism. Moreover, the lipotoxicity reversion induced by eicosapentaenoic acid (EPA) or by a liver X receptor (LXR) agonist reinforces the hypothesis that RSV-mediated inhibition of palmitate channeling into triglyceride pools could be a key factor in the aggravation of palmitate-induced cytotoxicity.

Conclusions

Our results suggest that RSV exerts its cytotoxic role in cancer cells exposed to a saturated FA context primarily by triglyceride accumulation inhibition, probably leading to an intracellular palmitate accumulation that triggers a lipid-mediated cell death. Additionally, this cell death is promoted by ER stress through a CHOP-mediated apoptotic process and may represent a potential anticancer strategy.

Mitochondrial dysfunction in some triple-negative breast cancer cell lines: role of mTOR pathway and therapeutic potential

INTRODUCTION

Triple-negative breast cancer (TNBC) is a subtype of highly malignant breast cancer with poor prognosis. TNBC is not amenable to endocrine therapy and often exhibit resistance to current chemotherapeutic agents, therefore, further understanding of the biological properties of these cancer cells and development of effective therapeutic approaches are urgently needed.

METHODS

We first investigated the metabolic alterations in TNBC cells in comparison with other subtypes of breast cancer cells using molecular and metabolic analyses. We further demonstrated that targeting these alterations using specific inhibitors and siRNA approach could render TNBC cells more sensitive to cell death compared to other breast cancer subtypes.

RESULTS

We found that TNBC cells compared to estrogen receptor (ER) positive cells possess special metabolic characteristics manifested by high glucose uptake, increased lactate production, and low mitochondrial respiration which is correlated with attenuation of mTOR pathway and decreased expression of p70S6K. Re-expression of p70S6K in TNBC cells reverses their glycolytic phenotype to an active oxidative phosphorylation (OXPHOS) state, while knockdown of p70S6K in ER positive cells leads to suppression of mitochondrial OXPHOS. Furthermore, lower OXPHOS activity in TNBC cells renders them highly dependent on glycolysis and the inhibition of glycolysis is highly effective in targeting TNBC cells despite their resistance to other anticancer agents.

CONCLUSIONS

Our study shows that TNBC cells have profound metabolic alterations characterized by decreased mitochondrial respiration and increased glycolysis. Due to their impaired mitochondrial function, TNBC cells are highly sensitive to glycolytic inhibition, suggesting that such metabolic intervention may be an effective therapeutic strategy for this subtype of breast cancer cells.

Knockdown of AKT3 (PKBγ) and PI3KCA suppresses cell viability and proliferation and induces the apoptosis of glioblastoma multiforme T98G cells

Glioblastoma multiforme (GBM) is the most malignant and invasive human brain tumor that is difficult to treat and has a very poor prognosis. Thus, new therapeutic strategies that target GBM are urgently needed. The PI3K/AKT/PTEN signaling pathway is frequently deregulated in a wide range of cancers. The present study was designed to examine the inhibitory effect of AKT3 or PI3KCA siRNAs on GBM cell growth, viability, and proliferation.T98G cells were transfected with AKT3 and/or PI3KCA siRNAs. AKT3 and PI3KCA protein-positive cells were identified using FC and Western blotting. The influence of specific siRNAs on T98G cell viability, proliferation, cell cycle, and apoptosis was evaluated as well using FC. Alterations in the mRNA expression of AKT3, PI3KCA, and apoptosis-related genes were analyzed using QRT-PCR. Knockdown of AKT3 and/or PI3KCA genes in T98G cells led to a significant reduction in cell viability, the accumulation of subG1-phase cells and, a reduced fraction of cells in the S and G2/M phases. Additionally, statistically significant differences in the BAX/BCL-2 ratio and an increased percentage of apoptotic cells were found. The siRNA-induced AKT3 and PI3KCA mRNA knockdown may offer a novel therapeutic strategy to control the growth of human GBM cells.

Weight change therapy as a potential treatment for end-stage ovarian carcinoma

Patient: Female, 41

Final Diagnosis: Ovarian carcinoma

Symptoms: Ascites • hepatomegaly • weight loss

Medication: —

Clinical Procedure: —

Specialty: Oncology

Supercompetitor status of Drosophila Myc cells requires p53 as a fitness sensor to reprogram metabolism and promote viability

In growing tissues, cell fitness disparities can provoke interactions that promote stronger cells at the expense of the weaker in a process called cell competition. The mechanistic definition of cell fitness is not understood, nor is it understood how fitness differences are recognized. Drosophila cells with extra Myc activity acquire "supercompetitor" status upon confrontation with wild-type (WT) cells, prompting the latter's elimination via apoptosis. Here we show that such confrontation enhances glycolytic flux in Myc cells and promotes their fitness and proliferation in a p53-dependent manner. Whereas p53 loss in noncompeting Myc cells is inconsequential, its loss impairs metabolism, reduces viability, and prevents the killing activity of Myc supercompetitor cells. We propose that p53 acts as a general sensor of competitive confrontation to enhance the fitness of the "winner" population. Our findings suggest that the initial confrontation between precancerous and WT cells could enhance cancer cell fitness and promote tumor progression.

Role of carbohydrate response element-binding protein (ChREBP) in generating an aerobic metabolic phenotype and in breast cancer progression

BACKGROUND

The lipogenic transcription factor carbohydrate response element-binding protein (ChREBP) may play a key role in malignant progression of breast cancer by allowing metabolic adaptations to take place in response to changes in oxygenation.

METHODS

Immunohistochemical analysis of ChREBP was carried out in human breast tumour tissue microarrays representative of malignant progression from normal breast through to metastatic cancer. The ChREBP protein and mRNA expressions were then analysed in a series of breast cancers for correlative analysis with common and breast-specific hypoxia signatures, and survival.

RESULTS

In invasive ductal carcinoma, ChREBP correlated significantly with mean 'downregulated' hypoxia scores (r=0.3, P<0.015, n=67) and in two distinct breast progression arrays, ChREBP protein also increased with malignant progression (P<0.001). However, bioinformatic analysis of a large data set (2136 cases) revealed an apparent reversal in the relationship between ChREBP mRNA level and clinical outcome - not only being significantly correlated with increased survival (log rank P<0.001), but also downregulated in malignant tissue compared with adjacent normal tissue.

CONCLUSION

The ChREBP expression may be reflective of an aerobic metabolic phenotype that may conflict with hypoxia-induced signalling but provide a mechanism for growth at the oxygenated edge of the tumours.

β-alanine suppresses malignant breast epithelial cell aggressiveness through alterations in metabolism and cellular acidity in vitro

Background

Deregulated energetics is a property of most cancer cells. This phenomenon, known as the Warburg Effect or aerobic glycolysis, is characterized by increased glucose uptake, lactate export and extracellular acidification, even in the presence of oxygen. β-alanine is a non-essential amino acid that has previously been shown to be metabolized into carnosine, which functions as an intracellular buffer. Because of this buffering capacity, we investigated the effects of β-alanine on the metabolic cancerous phenotype.

Methods

Non-malignant MCF-10a and malignant MCF-7 breast epithelial cells were treated with β-alanine at 100 mM for 24 hours. Aerobic glycolysis was quantified by measuring extracellular acidification rate (ECAR) and oxidative metabolism was quantified by measuring oxygen consumption rate (OCR). mRNA of metabolism-related genes was quantified by qRT-PCR with corresponding protein expression quantified by immunoblotting, or by flow cytometry which was verified by confocal microscopy. Mitochondrial content was quantified using a mitochondria-specific dye and measured by flow cytometry.

Results

Cells treated with β-alanine displayed significantly suppressed basal and peak ECAR (aerobic glycolysis), with simultaneous increase in glucose transporter 1 (GLUT1). Additionally, cells treated with β-alanine exhibited significantly reduced basal and peak OCR (oxidative metabolism), which was accompanied by reduction in mitochondrial content with subsequent suppression of genes which promote mitochondrial biosynthesis. Suppression of glycolytic and oxidative metabolism by β-alanine resulted in the reduction of total metabolic rate, although cell viability was not affected. Because β-alanine treatment reduces extracellular acidity, a constituent of the invasive microenvironment that promotes progression, we investigated the effect of β-alanine on breast cell viability and migration. β-alanine was shown to reduce both cell migration and proliferation without acting in a cytotoxic fashion. Moreover, β-alanine significantly increased malignant cell sensitivity to doxorubicin, suggesting a potential role as a co-therapeutic agent.

Conclusion

Taken together, our results suggest that β-alanine may elicit several anti-tumor effects. Our observations support the need for further investigation into the mechanism(s) of action and specificity of β-alanine as a co-therapeutic agent in the treatment of breast tumors.

Peroxisome proliferator activated receptor α ligands as anticancer drugs targeting mitochondrial metabolism

Tumor cells show metabolic features distinctive from normal tissues, with characteristically enhanced aerobic glycolysis, glutaminolysis and lipid synthesis. Peroxisome proliferator activated receptor α (PPAR α) is activated by nutrients (fatty acids and their derivatives) and influences these metabolic pathways acting antagonistically to oncogenic Akt and c-Myc. Therefore PPAR α can be regarded as a candidate target molecule in supplementary anticancer pharmacotherapy as well as dietary therapeutic approach. This idea is based on hitting the cancer cell metabolic weak points through PPAR α mediated stimulation of mitochondrial fatty acid oxidation and ketogenesis with simultaneous reduction of glucose and glutamine consumption. PPAR α activity is induced by fasting and its molecular consequences overlap with the effects of calorie restriction and ketogenic diet (CRKD). CRKD induces increase of NAD+/NADH ratio and drop in ATP/AMP ratio. The first one is the main stimulus for enhanced protein deacetylase SIRT1 activity; the second one activates AMP-dependent protein kinase (AMPK). Both SIRT1 and AMPK exert their major metabolic activities such as fatty acid oxidation and block of glycolysis and protein, nucleotide and fatty acid synthesis through the effector protein peroxisome proliferator activated receptor gamma 1 α coactivator (PGC-1α). PGC-1α cooperates with PPAR α and their activities might contribute to potential anticancer effects of CRKD, which were reported for various brain tumors. Therefore, PPAR α activation can engage molecular interplay among SIRT1, AMPK, and PGC-1α that provides a new, low toxicity dietary approach supplementing traditional anticancer regimen.

Glucose promotes breast cancer aggression and reduces metformin efficacy

Metformin treatment has been associated with a decrease in breast cancer risk and improved survival. Metformin induces complex cellular changes, resulting in decreased tumor cell proliferation, reduction of stem cells, and apoptosis. Using a carcinogen-induced rodent model of mammary tumorigenesis, we recently demonstrated that overfeeding in obese animals is associated with a 50% increase in tumor glucose uptake, increased proliferation, and tumor cell reprogramming to an "aggressive" metabolic state. Metformin significantly inhibited these pro-tumorigenic effects. We hypothesized that a dynamic relationship exists between chronic energy excess (glucose by dose) and metformin efficacy/action. Media glucose concentrations above 5 mmol/L was associated with significant increase in breast cancer cell proliferation, clonogenicity, motility, upregulation/activation of pro-oncogenic signaling, and reduction in apoptosis. These effects were most significant in triple-negative breast cancer (TNBC) cell lines. High-glucose conditions (10 mmol/L or above) significantly abrogated the effects of metformin. Mechanisms of metformin action at normal vs. high glucose overlapped but were not identical; for example, metformin reduced IGF-1R expression in both the HER2+ SK-BR-3 and TNBC MDA-MB-468 cell lines more significantly at 5, as compared with 10 mmol/L glucose. Significant changes in gene profiles related to apoptosis, cellular processes, metabolic processes, and cell proliferation occurred with metformin treatment in cells grown at 5 mmol/L glucose, whereas under high-glucose conditions, metformin did not significantly increase apoptotic/cellular death genes. These data indicate that failure to maintain glucose homeostasis may promote a more aggressive breast cancer phenotype and alter metformin efficacy and mechanisms of action.

Alpha cyano-4-hydroxy-3-methoxycinnamic acid inhibits proliferation and induces apoptosis in human breast cancer cells

This study investigated the underlying mechanism of 4-hydroxy-3-methoxycinnamic acid (ACCA), on the growth of breast cancer cells and normal immortal epithelial cells, and compared their cytotoxic effects responses. Treatment of breast cancer cells (MCF-7, T47D, and MDA-231) with ACCA resulted in dose- and time-dependent decrease of cell proliferation, viability in colony formation assay, and programmed cell death (apoptosis) with minimal effects on non-tumoral cells. The ability of ACCA to suppress growth in cancer cells not expressing or containing defects in p53 gene indicates a lack of involvement of this critical tumor suppressor element in mediating ACCA-induced growth inhibition. Induction of apoptosis correlated with an increase in Bax protein, an established inducer of programmed cell death, and the ratio of Bax to Bcl-2, an established inhibitor of apoptosis. We also documented the ability of ACCA to inhibit the migration and invasion of MDA-231 cells with ACCA in vitro. Additionally, tumor growth of MDA-231 breast cancer cells in vivo was dramatically affected with ACCA. On the basis of its selective anticancer inhibitory activity on tumor cells, ACCA may represent a promising therapeutic drug that should be further evaluated as a chemotherapeutic agent for human breast cancer.

Clinical and molecular mechanisms favoring cancer initiation and progression in diabetic patients

Cancer incidence and mortality are higher among diabetic patients. This review examines the mechanisms, both general and site-specific, for this increase. Hyperglycemia and hyperinsulinemia, which are the major abnormalities that characterize diabetes, can promote cancer via both independent and synergic mechanisms. Insulin is both a metabolic hormone and a growth factor that promotes cell proliferation. When insulin levels are increased due to either insulin resistance or insulin treatment, their mitogenic effect is more marked in malignant cells that frequently overexpress the insulin receptor and, more specifically, its A isoform that has predominant mitogenic activity. Hyperglycemia provides energy for malignant cell proliferation and, via the peculiar energy utilization of cancer cells, favors cancer growth and neoangiogenesis. Additionally, diabetes-associated obesity has cancer-promoting effects due to mechanisms that are specific to excess fat cells (such as increased peripheral estrogens, increased pro-mitogen cytokines and growth factors). Also fat-associated chronic inflammation can favor cancer via the cell damage caused by reactive oxygen species (ROS) and via the production of inflammatory cytokines and transcription factors that stimulate cancer growth and invasiveness. Finally, the multiple drugs involved in the treatment of diabetes can also play a role. Diabetes-associated comorbidities, tissue-specific inflammation, and organ-specific dysfunctions can explain why the risk of cancer can differ by tissue type among diabetic patients. The increased risk of cancer-related mortality is moderate among individual patients with diabetes (RR = 1.25), but the pandemic nature of the disease means that a considerable number of lives could be spared through a better understanding of the factors associating diabetes and cancer.

A PET-compatible tissue bioreactor for research, discovery, and validation of imaging biomarkers and radiopharmaceuticals: system design and proof-of-concept studies

Research and discovery of novel radiopharmaceuticals and targets thereof generally involves initial studies in cell cultures, followed by animal studies, both of which present several inherent limitations. The objective of this work was to develop a tissue bioreactor (TBR) enabling modulation of the microenvironment and to integrate the TBR with a small-animal PET scanner to facilitate imaging biomarker research and discovery and validation of radiopharmaceuticals.

METHODS

The TBR chamber is a custom-blown, water-jacketed, glass vessel enclosed in a circulating perfusion bath powered by a peristaltic pump, which is integrated within the field of view of the PET scanner. The chamber is in series with a gas exchanger and a vessel for degassing the system during filling. Dissolved oxygen/temperature probes and septa for injection or sampling are located at the inlet and outlet of the cell chamber. A pH probe is located at the chamber outlet. Effluent is collected in the fraction collector as mixed-cup samples. In addition, both medium and tissue chamber can be sampled to investigate tissue and secretory products through multiscale analysis. As a proof of concept, we studied the effects of lipids on glucose uptake using HepG2 cells. To that end, we varied the nutrient substrate environment over a period of approximately 27 d, before and after the addition of lipids, and studied the effects of pioglitazone, a peroxisome proliferator-activated receptor γ agonist, on lipid and glucose uptake. In parallel, the TBR was imaged by PET in conjunction with (11)C-palmitate in the presence and absence of lipids to characterize (11)C-palmitate uptake.

RESULTS

The O2 consumption, glucose consumption, lactate production, and free fatty acid consumption and production rates were consistent in demonstrating the effects of lipids on glucose uptake. Pioglitazone exhibited improved glucose uptake within 3 d of treatment. Semiquantitative analysis suggested that lipids induced greater (11)C-palmitate uptake.

CONCLUSION

The integrated TBR offers a platform to monitor and modulate the tissue microenvironment, thus facilitating tissue-specific imaging and therapeutic biomarkers of disease, identification of molecular diagnostic markers, and validation of radiopharmaceuticals in both rodent and human cell lines.

Cross-talk between HIF and p53 as mediators of molecular responses to physiological and genotoxic stresses

Abnormal rates of growth together with metastatic potential and lack of susceptibility to cellular signals leading to apoptosis are widely investigated characteristics of tumors that develop via genetic or epigenetic mechanisms. Moreover, in the growing tumor, cells are exposed to insufficient nutrient supply, low oxygen availability (hypoxia) and/or reactive oxygen species. These physiological stresses force them to switch into more adaptable and aggressive phenotypes. This paper summarizes the role of two key mediators of cellular stress responses, namely p53 and HIF, which significantly affect cancer progression and compromise treatment outcomes. Furthermore, it describes cross-talk between these factors.

Nuclear PKM2 expression predicts poor prognosis in patients with esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common tumors worldwide, with a high malignant degree and poor prognosis. The present study aims to investigate the relationship between pyruvate kinase M2 (PKM2) expression and the prognosis of patients with ESCC. The expression of PKM2 in 86 cases of esophageal carcinoma tissues was tested using immunohistochemistry. The relationship between PKM2 expression and clinical pathological parameters, and their effects on the prognosis of patients with ESCC were analyzed. The expression levels of PKM2 in both cytoplasm and nucleus of ESCC tissues were significantly higher than those in paracancerous tissues (P=6.73×10(-9) and 4.32×10(-6), respectively). The Kaplan-Meier analysis showed that nuclear PKM2 expression was closely related to the survival of patients with ESCC (P=0.005). Patients with high PKM2 expression in the nucleus had significantly shorter survival times than those with low PKM2 expression in the nucleus (hazard ratio for death, 2.358; 95% confidence interval, 1.156-4.812; P=0.018). No other significant difference was found between PMK2 expression and clinico-pathological features of ESCC patients (all P>0.05). In conclusion, high PKM2 expression in the nucleus is essential in the pathogenic process of ESCC and may be used to predict the prognosis of patients with ESCC.