Intermittent calorie restriction enhances epithelial-mesenchymal transition through the alteration of energy metabolism in a mouse tumor model

"Nutrient-fungi-host" tripartite interaction in cancer progression

The human microbiome exhibits a profound connection with the cancer development, progression, and therapeutic response, with particular emphasis on its components of the mycobiome, which are still in the early stages of research. In this review, we comprehensively summarize cancer-related symbiotic and pathogenic fungal genera. The intricate mechanisms through which fungi impact cancer as an integral member of both gut and tissue-resident microbiomes are further discussed. In addition, we shed light on the pivotal physiological roles of various nutrients, including cholesterol, carbohydrates, proteins and minerals, in facilitating the growth, reproduction, and invasive pathogenesis of the fungi. While our exploration of the interplay between nutrients and cancer, mediated by the mycobiome, is ongoing, the current findings have yet to yield conclusive results. Thus, delving into the relationship between nutrients and fungal pathogenesis in cancer development and progression would provide valuable insights into anticancer therapy and foster precision nutrition and individualized treatments that target fungi from bench to bedside.

Insulin-Lowering Diets in Metastatic Cancer

Hyperinsulinemia is an independent risk factor for cancer mortality. Insulin-lowering dietary strategies such as calorie restriction (CR), low-carbohydrate or ketogenic diets (KD), and intermittent fasting (IF) are aimed at reducing systemic stores of nutrients utilized by cancer cells, attenuating insulin-related growth signaling, and improving obesity-related metabolic parameters. In this narrative review, we searched the published literature for studies that tested various insulin-lowering diets in metastatic cancer in preclinical and clinical settings. A total of 23 studies were identified. Of these, 14 were preclinical studies of dietary strategies that demonstrated improvements in insulin levels, inhibition of metastasis, and/or reduction in metastatic disease burden in animal models. The remaining nine clinical studies tested carbohydrate restriction, KD, or IF strategies which appear to be safe and feasible in patients with metastatic cancer. These approaches have also been shown to improve serum insulin and other metabolic parameters. Though promising, the anti-cancer efficacy of these interventions, such as impact on tumor response, disease-specific-, and overall survival, have not yet been conclusively demonstrated. Studies that are adequately powered to evaluate whether insulin-lowering diets improve cancer outcomes are warranted.

Health Effects of Alternate Day Fasting Versus Pair-Fed Caloric Restriction in Diet-Induced Obese C57Bl/6J Male Mice

Alternate day fasting (ADF) induces weight loss and improves various markers of health in rodents and humans. However, it is unclear whether the benefits of ADF are derived from the lower caloric intake of ADF or from the 24-h fasting period. Therefore, this study directly compared selected markers for health – such as glucose control, body weight, liver triglycerides, T cell frequencies, and others – in high-fat (60% calories from fat) diet-induced obese mice subjected to either ADF or caloric restriction (CR). Obese mice were randomly assigned to one of four groups: (1) ADF: remained on the high-fat diet, but fed on alternate days (n = 5), (2) PF: remained on the high-fat diet, but pair-fed to the ADF group (n = 5), (3) LF: moved to a chow ad libitum diet (n = 5; 17% calories from fat), and (4) HF: remained on the high-fat ad libitum diet (n = 5). An additional group of non-obese mice maintained on a chow diet since weaning were used as controls (CON: n = 5). After 10 weeks, ADF, PF, and LF mice ate fewer kcals, had a lower body mass, had smaller epididymal fat pads, improved glucose tolerance, and had a lower hepatic triglyceride content relative to HF mice (p < 0.05), but none reached that of CON mice in these measures. T cell frequencies of the spleen, blood, and mesenteric lymph nodes were reduced in ADF, PF, and HF compared to the CON group. Importantly, there were no significant differences between the ADF and PF groups in any of the measurements made in the current study. These data suggest that ADF, PF, and LF diets each lead to improved markers of health relative to high-fat diet-induced obese mice, and that the caloric restriction associated with ADF is the major factor for the noted improvements.

Roles of adiponectin and leptin signaling-related microRNAs in the preventive effects of calorie restriction in mammary tumor development

Calorie restriction (CR) is suggested to prevent the development of mammary tumors (MTs); however, the mechanism remains to be clarified. We aimed to determine the microRNA (miRNA) profile in mice applied to 2 different CR protocols; chronic (CCR) and intermittent (ICR) and follow the MT development. In addition, the roles of miRNAs involved in adiponectin and/or leptin signaling pathways were investigated. Mice were divided into 3 groups: ad-libitum (AL), CCR, or ICR, which comprised 3 weeks of AL feeding followed by 1 week of 60% CR in a cyclic manner. Blood and tissue collection were performed at weeks 10, 17/18, 49/50 and 81/82. Long-term CCR provided better protection compared with ICR for MT development with a delay in the MT occurrence. Adiponectin expression in mammary fat pad were significantly higher in CCR group compared with AL. Using GeneChip Array, 250 of 3195 miRNAs were differentially expressed among the dietary groups. Thirteen of 250 miRNAs were related to adiponectin and/or leptin signaling genes. Results were verified by reverse transcription polymerase chain reaction. Specifically, miR-326-3p, miR-500-3p and miR-129-5p, which are related to adiponectin and/or leptin signaling, may play important roles in the preventive effects of CR in MT development and in ageing. Thus, these miRNAs might be putative biomarkers to target for diagnostic and treatment purposes. Novelty: Type of CR and micro RNA interaction is related to ageing. miR-326-3p, miR-500-3p and miR-129-5p expression levels were differentially expressed in MT development and in ageing. The genes associated with adiponectin and/or leptin signaling pathways are regulated by certain miRNAs in the protective effects of CR.

Obesity and Cancer Metastasis: Molecular and Translational Perspectives

Obesity is a modern health problem that has reached pandemic proportions. It is an established risk factor for carcinogenesis, however, evidence for the contribution of adipose tissue to the metastatic behavior of tumors is also mounting. Over 90% of cancer mortality is attributed to metastasis and metastatic tumor cells must communicate with their microenvironment for survival. Many of the characteristics observed in obese adipose tissue strongly mirror the tumor microenvironment. Thus in the case of prostate, pancreatic and breast cancer and esophageal adenocarcinoma, which are all located in close anatomical proximity to an adipose tissue depot, the adjacent fat provides an ideal microenvironment to enhance tumor growth, progression and metastasis. Adipocytes provide adipokines, fatty acids and other soluble factors to tumor cells whilst immune cells infiltrate the tumor microenvironment. In addition, there are emerging studies on the role of the extracellular vesicles secreted from adipose tissue, and the extracellular matrix itself, as drivers of obesity-induced metastasis. In the present review, we discuss the major mechanisms responsible for the obesity-metastatic link. Furthermore, understanding these complex mechanisms will provide novel therapies to halt the tumor-adipose tissue crosstalk with the ultimate aim of inhibiting tumor progression and metastatic growth.

The Metabolic Heterogeneity and Flexibility of Cancer Stem Cells

Simple Summary

Cancer stem cells (CSCs) have been shown to be the main cause of therapy resistance and cancer recurrence. An analysis of their biological properties has revealed that CSCs have a particular metabolism that differs from non-CSCs to maintain their stemness properties. In this review, we analyze the flexible metabolic mechanisms of CSCs and highlight the new therapeutics that target CSC metabolism.

Abstract

Numerous findings have indicated that CSCs, which are present at a low frequency inside primary tumors, are the main cause of therapy resistance and cancer recurrence. Although various therapeutic methods targeting CSCs have been attempted for eliminating cancer cells completely, the complicated characteristics of CSCs have hampered such attempts. In analyzing the biological properties of CSCs, it was revealed that CSCs have a peculiar metabolism that is distinct from non-CSCs to maintain their stemness properties. The CSC metabolism involves not only the catabolic and anabolic pathways, but also intracellular signaling, gene expression, and redox balance. In addition, CSCs can reprogram their metabolism to flexibly respond to environmental changes. In this review, we focus on the flexible metabolic mechanisms of CSCs, and highlight the new therapeutics that target CSC metabolism.

Diabetes mellitus is associated with liver metastasis of colorectal cancer through production of biglycan-rich cancer stroma

High morbidity and mortality of cancer, especially colorectal cancer (CRC), in diabetic patients have been reported. In this study, we investigated the relationship between the presence of diabetes mellitus (blood hemoglobin A1C was 6.5% or higher at the time of diagnosis of CRC) and the progression and liver metastasis of CRC. Histopathological findings in the primary lesions, which were preferential to diabetes-complicated CRC (DM-CRC) and the liver metastasis, were also investigated. Of the 473 CRC patients who underwent curative surgical resection, 148 (31%) had diabetes. In DM-CRC cases, the stage was more advanced, with more cases in stage IV or postoperative disease recurrence. Histopathological findings correlated with liver metastasis in DM-CRC, including budding grade, perineural invasion, and myxomatous tumor stroma, and all were highly correlated with the stage. Additionally, myxomatous stroma showed the strongest correlation with liver metastasis in multivariate analysis. Myxomatous stroma in stage III cases correlated with liver recurrence. The myxomatous stroma was abundant in biglycan protein and contained numerous CD90-positive mesenchymal stem cells (MSCs). In human colon cancer cell line HT29, biglycan expression was induced by high sugar concentration, fatty acids, and insulin, and its contact co-culture with MSCs resulted in enhanced stemness and epithelial-mesenchymal transition phenotype. Thus, DM-CRC has higher malignant phenotypes compared to non-DM-CRC, and the involvement of diabetes-induced biglycan may act as a pathogenic factor.

Effects of short-term fasting on cancer treatment

Growing preclinical evidence shows that short-term fasting (STF) protects from toxicity while enhancing the efficacy of a variety of chemotherapeutic agents in the treatment of various tumour types. STF reinforces stress resistance of healthy cells, while tumor cells become even more sensitive to toxins, perhaps through shortage of nutrients to satisfy their needs in the context of high proliferation rates and/or loss of flexibility to respond to extreme circumstances. In humans, STF may be a feasible approach to enhance the efficacy and tolerability of chemotherapy. Clinical research evaluating the potential of STF is in its infancy. This review focuses on the molecular background, current knowledge and clinical trials evaluating the effects of STF in cancer treatment. Preliminary data show that STF is safe, but challenging in cancer patients receiving chemotherapy. Ongoing clinical trials need to unravel if STF can also diminish toxicity and increase efficacy of chemotherapeutic regimes in daily practice.

Co-occurring KRAS mutation/LKB1 loss in non-small cell lung cancer cells results in enhanced metabolic activity susceptible to caloric restriction: an in vitro integrated multilevel approach

Background

Non–small-cell lung cancer (NSCLC) is a heterogeneous disease, with multiple different oncogenic mutations. Approximately 25–30% of NSCLC patients present KRAS mutations, which confer poor prognosis and high risk of tumor recurrence. About half of NSCLCs with activating KRAS lesions also have deletions or inactivating mutations in the serine/threonine kinase 11 (LKB1) gene. Loss of LKB1 on a KRAS-mutant background may represent a significant source of heterogeneity contributing to poor response to therapy.

Methods

Here, we employed an integrated multilevel proteomics, metabolomics and functional in-vitro approach in NSCLC H1299 isogenic cells to define their metabolic state associated with the presence of different genetic background. Protein levels were obtained by label free and single reaction monitoring (SRM)-based proteomics. The metabolic state was studied coupling targeted and untargeted mass spectrometry (MS) strategy. In vitro metabolic dependencies were evaluated using 2-deoxy glucose (2-DG) treatment or glucose/glutamine nutrient limitation.

Results

Here we demonstrate that co-occurring KRAS mutation/LKB1 loss in NSCLC cells allowed efficient exploitation of glycolysis and oxidative phosphorylation, when compared to cells with each single oncologic genotype. The enhanced metabolic activity rendered the viability of cells with both genetic lesions susceptible towards nutrient limitation.

Conclusions

Co-occurrence of KRAS mutation and LKB1 loss in NSCLC cells induced an enhanced metabolic activity mirrored by a growth rate vulnerability under limited nutrient conditions relative to cells with the single oncogenetic lesions. Our results hint at the possibility that energy stress induced by calorie restriction regimens may sensitize NSCLCs with these co-occurring lesions to cytotoxic chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0954-5) contains supplementary material, which is available to authorized users.