Dual role of insulin-like growth factor-1 in acetyl-CoA carboxylase-alpha activity in human colon cancer cells HCT-8: downregulating its expression and phosphorylation

Lipid metabolism, amino acid metabolism, and prostate cancer: a crucial metabolic journey

Prostate cancer (PCa) is one of the most common malignancies in males worldwide, and its development and progression involve the regulation of multiple metabolic pathways. Alterations in lipid metabolism affect the proliferation and metastatic capabilities of PCa cells. Cancer cells increase lipid synthesis and regulate fatty acid oxidation to meet their growth and energy demands. Similarly, changes occur in amino acid metabolism in PCa. Cancer cells exhibit an increased demand for specific amino acids, and they regulate amino acid transport and metabolic pathways to fulfill their proliferation and survival requirements. These changes are closely associated with disease progression and treatment response in PCa cells. Therefore, a comprehensive investigation of the metabolic characteristics of PCa is expected to offer novel insights and approaches for the early diagnosis and treatment of this disease.

Targeting cancer-specific metabolic pathways for developing novel cancer therapeutics

Cancer is a heterogeneous disease characterized by various genetic and phenotypic aberrations. Cancer cells undergo genetic modifications that promote their proliferation, survival, and dissemination as the disease progresses. The unabated proliferation of cancer cells incurs an enormous energy demand that is supplied by metabolic reprogramming. Cancer cells undergo metabolic alterations to provide for increased energy and metabolite requirement; these alterations also help drive the tumor progression. Dysregulation in glucose uptake and increased lactate production via "aerobic glycolysis" were described more than 100 years ago, and since then, the metabolic signature of various cancers has been extensively studied. However, the extensive research in this field has failed to translate into significant therapeutic intervention, except for treating childhood-ALL with amino acid metabolism inhibitor L-asparaginase. Despite the growing understanding of novel metabolic alterations in tumors, the therapeutic targeting of these tumor-specific dysregulations has largely been ineffective in clinical trials. This chapter discusses the major pathways involved in the metabolism of glucose, amino acids, and lipids and highlights the inter-twined nature of metabolic aberrations that promote tumorigenesis in different types of cancer. Finally, we summarise the therapeutic interventions which can be used as a combinational therapy to target metabolic dysregulations that are unique or common in blood, breast, colorectal, lung, and prostate cancer.

Comparative proteomic analysis of children FSGS FFPE tissues

BACKGROUND

In children, focal segmental glomerulosclerosis (FSGS) is the main cause of steroid resistant nephrotic syndrome (SRNS). To identify specific candidates and the mechanism of steroid resistance, we examined the formalin-fixed paraffin embedded (FFPE) renal tissue protein profiles via liquid chromatography tandem mass spectrometry (LC-MS/MS).

METHODS

Renal biopsies from seven steroid-sensitive (SS) and eleven steroid-resistant (SR) children FSGS patients were obtained. We examined the formalin-fixed paraffin embedded (FFPE) renal tissue protein profiles via liquid chromatography tandem mass spectrometry (LC-MS/MS). Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and Gene Ontology (GO) analysis, as well as the construction of protein-protein interaction (PPI) network were performed. Two proteins were further valiadated by immunohistochemistry staining in FSGS patients and mice models.

RESULTS

In total, we quantified more than 4000 proteins, of which 325 were found to be differentially expressed proteins (DEPs) between the SS and SR group (foldchange ≥2, P<0.05). The results of GO revealed that the most significant up-regulated proteins were primarily related to protein transportation, regulation of the complement activation process and cytolysis. Moreover, clustering analysis showed differences in the pathways (lysosome, terminal pathway of complement) between the two groups. Among these potential candidates, validation analyses for LAMP1 and ACSL4 were conducted. LAMP1 was observed to have a higher expression in glomerulus, while ACSL4 was expressed more in tubular epithelial cells.

CONCLUSIONS

In this study, the potential mechanism and candidates related to steroid resistance in children FSGS patients were identified. It could be helpful in identifying potential therapeutic targets and predicting outcomes with these proteomic changes for children FSGS patients.

Glucose Concentration in Cell Culture Medium Influences the BRCA1-Mediated Regulation of the Lipogenic Action of IGF-I in Breast Cancer Cells

Hyperglycaemia is a common metabolic alteration associated with breast cancer risk and progression. We have previously reported that BRCA1 restrains metabolic activity and proliferative response to IGF-I anabolic actions in breast cancer cells cultured in high glucose. Here, we evaluated the impact of normal physiological glucose on these tumour suppressive roles of BRCA1. Human breast cancer cells cultured in normal physiological and high glucose were treated with IGF-I (0-500 ng/mL). Cellular responses were evaluated using immunoblotting, co-immunoprecipitation, and cell viability assay. As we previously reported, IGF-I induced ACCA dephosphorylation by reducing the association between BRCA1 and phosphorylated ACCA in high glucose, and upregulated FASN abundance downstream of ACCA. However, these effects were not observed in normal glucose. Normal physiological glucose conditions completely blocked IGF-I-induced ACCA dephosphorylation and FASN upregulation. Co-immunoprecipitation studies showed that normal physiological glucose blocked ACCA dephosphorylation by increasing the association between BRCA1 and phosphorylated ACCA. Compared to high glucose, the proliferative response of breast cancer cells to IGF-I was reduced in normal glucose, whereas no difference was observed in normal mammary epithelial cells. Considering these results collectively, we conclude that normal physiological glucose promotes the novel function of BRCA1 as a metabolic restraint of IGF-I actions. These data suggest that maintaining normal glucose levels may improve BRCA1 function in breast cancer and slow down cancer progression.

A New Twist in Protein Kinase B/Akt Signaling: Role of Altered Cancer Cell Metabolism in Akt-Mediated Therapy Resistance

Cancer resistance to chemotherapy, radiotherapy and molecular-targeted agents is a major obstacle to successful cancer therapy. Herein, aberrant activation of the phosphatidyl-inositol-3-kinase (PI3K)/protein kinase B (Akt) pathway is one of the most frequently deregulated pathways in cancer cells and has been associated with multiple aspects of therapy resistance. These include, for example, survival under stress conditions, apoptosis resistance, activation of the cellular response to DNA damage and repair of radiation-induced or chemotherapy-induced DNA damage, particularly DNA double strand breaks (DSB). One further important, yet not much investigated aspect of Akt-dependent signaling is the regulation of cell metabolism. In fact, many Akt target proteins are part of or involved in the regulation of metabolic pathways. Furthermore, recent studies revealed the importance of certain metabolites for protection against therapy-induced cell stress and the repair of therapy-induced DNA damage. Thus far, the likely interaction between deregulated activation of Akt, altered cancer metabolism and therapy resistance is not yet well understood. The present review describes the documented interactions between Akt, its target proteins and cancer cell metabolism, focusing on antioxidant defense and DSB repair. Furthermore, the review highlights potential connections between deregulated Akt, cancer cell metabolism and therapy resistance of cancer cells through altered DSB repair and discusses potential resulting therapeutic implications.

Elucidating the novel BRCA1 function as a non-genomic metabolic restraint in ER-positive breast cancer cell lines

Within populations carrying the same genetic predisposition, the penetrance of BRCA1 mutations has increased over time. Although linked to changes in lifestyle factors associated with energy metabolism, these observations cannot be explained by the established role of BRCA1 in DNA repair alone. We manipulated BRCA1 expression using tetracycline in the UBR60-bcl2 cell line (which has an inducible, tetracycline-regulated BRCA1 expression) and siRNA in oestrogen receptor(ER)-positive MCF7 and T47D breast cancer cells. Cellular responses to BRCA1 silencing and IGF-I actions were investigated using western blotting, 3-H Thymidine incorporation assay, cell fractionation and co-immunoprecipitation. We demonstrated that the loss of BRCA1 resulted in downregulation of a phosphorylated and inactive form of acetyl CoA Carboxylase-α (ACCA), with a concomitant increase in fatty acid synthase (FASN) abundance. BRCA1 was predominantly cytoplasmic in ER-positive breast cancer cells, compatible with the observation that BRCA1 physically associates with phosphorylated ACCA, which is a cytoplasmic protein. We also found that IGF-I induced de-phosphorylation of ACCA by reducing the interaction between BRCA1 and phosphorylated ACCA. BRCA1 deficiency enhanced the non-genomic effects of IGF-I, as well as the proliferative responses of cells to IGF-I. We characterized a novel, non-genomic role for BRCA1 in restraining metabolic activity and IGF-I anabolic actions.

Functional characterization of AMP-activated protein kinase signaling in tumorigenesis

AMP-activated protein kinase (AMPK) is a ubiquitously expressed metabolic sensor among various species. Specifically, cellular AMPK is phosphorylated and activated under certain stressful conditions, such as energy deprivation, in turn to activate diversified downstream substrates to modulate the adaptive changes and maintain metabolic homeostasis. Recently, emerging evidences have implicated the potential roles of AMPK signaling in tumor initiation and progression. Nevertheless, a comprehensive description on such topic is still in scarcity, especially in combination of its biochemical features with mouse modeling results to elucidate the physiological role of AMPK signaling in tumorigenesis. Hence, we performed this thorough review by summarizing the tumorigenic role of each component along the AMPK signaling, comprising of both its upstream and downstream effectors. Moreover, their functional interplay with the AMPK heterotrimer and exclusive efficacies in carcinogenesis were chiefly explained among genetically altered mice models. Importantly, the pharmaceutical investigations of AMPK relevant medications have also been highlighted. In summary, in this review, we not only elucidate the potential functions of AMPK signaling pathway in governing tumorigenesis, but also potentiate the future targeted strategy aiming for better treatment of aberrant metabolism-associated diseases, including cancer.

Effect of growth factors, estradiol 17-β, and short chain fatty acids on the intestinal HT29-MTX cells : Growth factors and SCFAs effects on intestinal E12 cells

Peptides growth factors, hormones, and short chain fatty acids (SCFAs) are constantly in contact with the human bowel when secreted by gland or ingested by food, as milk and colostrum, or, as in the case of SCFAs, produced by fermentation processes. This study considers the effect of growth factors, estradiol 17-β, and SCFAs on the metabolic activity and proliferation of undifferentiated HT29-MTX-E12 (E12) cells. In particular, the aim of the present study was the characterization of the human intestinal cell line E12 for its suitability as an in vitro intestinal model for cell-nutrient interaction studies. The effect of insulin-like growth factors (IGF)-I, epidermal growth factors (EGF), transforming growth factor alpha (TGF-α), transforming growth factor beta (TGF-β), estradiol 17-β and butyrate, propionate, and acetate was assessed on metabolic activity and proliferation of E12 cells using AlamarBlue(TM) assay and PicoGreen® assay, respectively. IGF-I and estradiol 17-β significantly (P < 0.05; P < 0.001) increased both metabolic activity and proliferation in a concentration-dependent manner, whereas TGF-α, at the concentration of 1 ng/mL, significantly (P < 0.05) reduced the metabolic activity of the cells. Further, a dose-dependent inhibition of cell metabolic activity was detected in the presence of all SCFAs tested. Butyrate showed to be the most active in the inhibition of E12 metabolic activity and its effect was enhanced by the presence of propionate and acetate. E12 cells, in undifferentiated state, showed to be a suitable in vitro model for cell-nutrient interaction studies, providing an opportunity to examine the potential role of growth factors, hormones and SCFAs in the regulation of the intestinal cell viability.

Endocrine-related cancers and the role of AMPK

AMP-activated protein kinase (AMPK) is a master regulator of energy homeostasis involved in the regulation of a number of physiological processes including β-oxidation of fatty acids, lipogenesis, protein and cholesterol synthesis, as well as cell cycle inhibition and apoptosis. Important changes to these processes are known to occur in cancer due to changes in AMPK activity within cancer cells and in the periphery. This review aims to present findings relating to the role and regulation of AMPK in endocrine-related cancers. Obesity is a known risk factor for many types of cancers and a number of endocrine factors, including adipokines and steroid hormones, are regulated by and regulate AMPK. A clear role for AMPK in breast cancer is evident from the already impressive body of work published to date. However, information pertaining to its role in prostate cancer is still contentious, and future work should unravel the intricacies behind its role to inhibit, in some cases, and stimulate cancer growth in others. This review also presents data relating to the role of AMPK in cancers of the endometrium, ovary and colon, and discusses the possible use of AMPK-activating drugs including metformin for the treatment of all endocrine-related cancers.

Dysregulated lipid metabolism in cancer

Alteration of lipid metabolism has been increasingly recognized as a hallmark of cancer cells. The changes of expression and activity of lipid metabolizing enzymes are directly regulated by the activity of oncogenic signals. The dependence of tumor cells on the dysregulated lipid metabolism suggests that proteins involved in this process are excellent chemotherapeutic targets for cancer treatment. There are currently several drugs under development or in clinical trials that are based on specifically targeting the altered lipid metabolic pathways in cancer cells. Further understanding of dysregulated lipid metabolism and its associated signaling pathways will help us to better design efficient cancer therapeutic strategy.

Insulin-like growth factor-1 boosts the developing process of condylar hyperplasia by stimulating chondrocytes proliferation

OBJECTIVE

The etiology of Condylar hyperplasia (CH) of human temporomandibular joint (TMJ) remains largely unknown. Our previous study has demonstrated that enriched insulin-like growth factor-1(IGF-1) was expressed in the proliferation and hypertrophic layers of CH cartilage. Accordingly, this study was aimed to investigate whether IGF-1 regulates CH chondrocytes proliferation in condylar cartilage overgrowth and explore the molecular mechanism of IGF-1 involved in.

METHODS

Chondrocytes were isolated from 6 CH and 3 normal cartilage (NC) specimens and cultured in alginate beads or monolayer, treated with IGF-1 or specific inhibitors such as 7-[trans-3-[(azetidin-1-yl)methyl]cyclobutyl]-5-(3-benzyloxyphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-amine (NVP-AEW541), U0126, and LY294002. Thereafter, cellular proliferation capacity was evaluated by Cell Viability Analyzer (alginate beads culture) or 3-(4,5-dimethylthiazo(-2-yl)-2,5-diphenyltetrazolium bromide (MTT) (monolayer culture). Gene expression levels of IGF-1, IGF-1 receptor (IGF-1R), collagen type II, type X and those genes associated with proliferation were evaluated by realtime PCR. Protein levels of IGF-1 and IGF-1R synthesized by CH chondrocytes were accessed by enzyme-linked immunosorbent assay (ELISA) and western blotting.

RESULTS

CH chondrocytes enhanced cellular proliferation capacity and expressed significantly higher levels of messenger RNA (mRNA) and protein expressions of IGF-1 and IGF-1R, as compared with NC chondrocytes. Furthermore, enriched IGF-1 enhanced CH chondrocytes proliferation, up-regulated the expressions of specific genes associated with cellular proliferation and elevated the gene expression of collagen type II A1 (COL2A1). Besides, IGF-1-mediated CH chondrocytes proliferation mainly depended on the mitogen-activated protein kinase (MAPK)-ERK pathway.

CONCLUSIONS

IGF-1 promotes human TMJ cartilage overgrowth in the developing process of CH by enhancing chondrocytes proliferation via MAPK-ERK pathway.

AMPK and gastrointestinal carcinoma

Activation of adenosine monophosphate activated protein kinase (AMPK) not only affects gastrointestinal cancer cell growth and proliferation by regulating cholesterol metabolism, fatty acid synthesis and protein synthesis, but also promotes gastrointestinal cancer cell cycle arrest by regulating cell cycle progression. Moreover, activation of AMPK activates caspase-9 and then induces the apoptosis of gastrointestinal cancer cells. In addition, AMPK is closely related with angiogenesis, invasion and metastasis of gastrointestinal cancer. This review aims to elucidate the relationship between AMPK and gastrointestinal cancer.