Targeting at cancer energy metabolism and lipid droplet formation as new treatment strategies for epigallocatechin-3-gallate (EGCG) in colorectal cancer cells

Phytochemicals regulate cancer metabolism through modulation of the AMPK/PGC-1α signaling pathway

BACKGROUND

Due to the complex pathophysiological mechanisms involved in cancer progression and metastasis, current therapeutic approaches lack efficacy and have significant adverse effects. Therefore, it is essential to establish novel strategies for combating cancer. Phytochemicals, which possess multiple biological activities, such as antioxidant, anti-inflammatory, antimutagenic, immunomodulatory, antiproliferative, anti-angiogenesis, and antimetastatic properties, can regulate cancer progression and interfere in various stages of cancer development by suppressing various signaling pathways.

METHODS

The current systematic and comprehensive review was conducted based on Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) criteria, using electronic databases, including PubMed, Scopus, and Science Direct, until the end of December 2023. After excluding unrelated articles, 111 related articles were included in this systematic review.

RESULTS

In this current review, the major signaling pathways of cancer metabolism are highlighted with the promising anticancer role of phytochemicals. This was through their ability to regulate the AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) signaling pathway. The AMPK/PGC-1α signaling pathway plays a crucial role in cancer cell metabolism via targeting energy homeostasis and mitochondria biogenesis, glucose oxidation, and fatty acid oxidation, thereby generating ATP for cell growth. As a result, targeting this signaling pathway may represent a novel approach to cancer treatment. Accordingly, alkaloids, phenolic compounds, terpene/terpenoids, and miscellaneous phytochemicals have been introduced as promising anticancer agents by regulating the AMPK/PGC-1α signaling pathway. Novel delivery systems of phytochemicals targeting the AMPK/PGC-1α pathway in combating cancer are also highlighted in this review.

Epigallocatechin gallate suppresses mitotic clonal expansion and adipogenic differentiation of preadipocytes through impeding JAK2/STAT3-mediated transcriptional cascades

BACKGROUND

Mitotic clonal expansion (MCE) is a prerequisite for preadipocyte differentiation and adipogenesis. Epigallocatechin gallate (EGCG) has been shown to inhibit preadipocyte differentiation. However, the exact molecular mechanisms are still elusive.

PURPOSE

This study investigated whether EGCG could inhibit adipogenesis and lipid accumulation by regulating the cell cycle in the MCE phase of adipogenesis and its underlying molecular mechanisms.

METHOD

3T3-L1 preadipocytes were induced to differentiate by a differentiation cocktail (DMI) and were treated with EGCG (25-100 μM) for 9, 18, and 24 h to examine the effect on MCE, or eight days to examine the effect on terminal differentiation. C57BL/6 mice were fed a high-fat diet (HFD) for three months to induce obesity and were given EGCG (50 or 100 mg/kg) daily by gavage.

RESULTS

We showed that EGCG significantly inhibited terminal adipogenesis and lipid accumulation in 3T3-L1 cells and decreased expressions of PPARγ, C/EBPα, and FASN. Notably, at the MCE phase, EGCG regulated the cell cycle in sequential order, induced G0/G1 arrest at 18 h, and inhibited the G2/M phase at 24 h upon DMI treatment. Meanwhile, EGCG regulated the expressions of cell cycle regulators (cyclin D1, cyclin E1, CDK4, CDK6, cyclin B1, cyclin B2, p16, and p27), and decreased C/EBPβ, PPARγ, and C/EBPα expressions at MCE. Mechanistic studies using STAT3 agonist Colivelin and antagonist C188-9 revealed that EGCG-induced cell cycle arrest in the MCE phase and terminal adipocyte differentiation was mediated by the inhibition of JAK2/STAT3 signaling cascades and STAT3 (Tyr705) nuclear translocation. Furthermore, EGCG significantly protected mice from HFD-induced obesity, reduced body weight and lipid accumulations in adipose tissues, reduced hyperlipidemia and leptin levels, and improved glucose intolerance and insulin sensitivity. Moreover, RNA sequencing (RNA-seq) analysis showed that the cell cycle changes in epididymal white adipose tissue (eWAT) were significantly enriched upon EGCG treatment. We further verified that EGCG treatment significantly reduced expressions of adipogenic factors, cell cycle regulators, and p-STAT3 in eWAT.

CONCLUSION

EGCG inhibits MCE, resulting in the inhibition of early and terminal adipocyte differentiation and lipid accumulation, which were mediated by inhibiting p-STAT3 nucleus translocation and activation.

Encapsulation of (-)-epigallocatechin gallate (EGCG) within phospholipid-based nanovesicles using W/O emulsion-transfer methods: Masking bitterness and delaying release of EGCG

A novel phospholipid-based nanovesicle (PBN) was developed to encapsulate (-)-epigallocatechin gallate (EGCG), a major polyphenol in green tea, to mask its bitter taste and expand its application in food products. The PBN was formed using W/O emulsion-transfer methods and showed a multilayer membrane nanovesicle structure (around 200 nm) observed with TEM. The PBN possessed a high encapsulation efficiency (92.1%) for EGCG. The bitterness of EGCG was significantly reduced to 1/12 after encapsulation. Fourier transform infrared spectroscopy (FTIR) indicated the EGCG mainly interacted with the upper chain/glycerol/head group region of the lipid bilayerin PBN. Quartz crystal microbalance with dissipation (QCM-D) showed the addition of γ-cyclodextrin in PBN enhanced EGCG's adsorption with phospholipids and allowed for its good sustained release. Encapsulating EGCG in PBN inhibited its complexation with mucin, reducing bitterness and astringency. This provides a new method to improve EGCG's flavor, potentially expanding its application in the food industry.

Bimodal effects on lipid droplets induced in cancer and non-cancer cells by chemotherapy drugs as revealed with a green-emitting BODIPY fluorescent probe

Lipid droplets (LDs) are cytoplasmic lipid-rich organelles with important roles in lipid storage and metabolism, cell signaling and membrane biosynthesis. Additionally, multiple diseases, such as obesity, fatty liver, cardiovascular diseases and cancer, are related to the metabolic disorders of LDs. In various cancer cells, LD accumulation is associated with resistance to cell death, reduced effectiveness of chemotherapeutic drugs, and increased proliferation and aggressiveness. In this work, we present a new viscosity-sensitive, green-emitting BODIPY probe capable of distinguishing between ordered and disordered lipid phases and selectively internalising into LDs of live cells. Through the use of fluorescence lifetime imaging microscopy (FLIM), we demonstrate that LDs in live cancer (A549) and non-cancer (HEK 293T) cells have vastly different microviscosities. Additionally, we quantify the microviscosity changes in LDs under the influence of DNA-damaging chemotherapy drugs doxorubicin and etoposide. Finally, we show that doxorubicin and etoposide have different effects on the microviscosities of LDs in chemotherapy-resistant A549 cancer cells.

Mutual impact of adipocytes and colorectal cancer cells growing in co-culture conditions

BACKGROUND

Colorectal cancer (CRC) is the third most common malignancy worldwide. CRC cells are situated in an adipocyte-rich microenvironment, which leads to interactions between adipocytes and CRC cells. Upon exposure to cancer cells, adipocytes transform into cancer-associated adipocytes (CAAs), and as a result, they gain features that promote tumor progression. The aim of this research was to shed more light on the detailed role of interactions between adipocytes and CRC cells associated with cancer progression in the context of these alterations.

METHODS

To implement adipocyte-CRC cell interaction, a co-culture model was applied. The analyses mainly focused on the metabolic modifications within CAAs and CRC cells, as well as the proliferation and migration potential of CRC cells. The impact of CRC on adipocytes was investigated by qRT-PCR analysis and Oil Red O staining. Proliferation and migration of CRC cells upon co-culture were tested with videomicroscopy, XTT, and a wound healing assay. Metabolic changes within CAAs and CRC cells were investigated based on lipid droplet formation, cell cycle analysis, gene and protein expression by qRT-PCR, and western blotting techniques.

RESULTS

CRC cells induced reprogramming of adipocytes into CAAs, which was connected with downregulation of lipid droplet formation in CAAs and alteration in adipocyte features. CAAs showed decreased metabolism-related gene expression, phosphorylation of Akt, ERK kinases, STAT3, and lactate secretion in comparison to the control. CAAs also promoted the migration, proliferation, and lipid droplet accumulation of CRC cells. After co-culturing with adipocytes, there was a shift to the G2/M phase of the cell cycle according to the differences in cyclin expression.

CONCLUSION

There are complex bidirectional interactions between adipocytes and CRC cells that may be connected with the induction of CRC cell progression. Video Abstract.

Lactoferrin-Based Ternary Composite Nanoparticles with Enhanced Dispersibility and Stability for Curcumin Delivery

Curcumin has been reported to exhibit free radical antioxidant, anti-inflammatory, and anticancer activities, which are beneficial for nutraceutical applications. However, its application for this purpose is limited by its poor water solubility, stability, and bioavailability. These problems can be overcome using food-grade colloidal particles that encapsulate, protect, and deliver curcumin. These colloidal particles can be assembled from structure-forming food components that may also exhibit protective effects, such as proteins, polysaccharides, and polyphenols. In this study, lactoferrin (LF), (-)-epigallocatechin gallate (EGCG), and hyaluronic acid (HA) were used to fabricate composite nanoparticles using a simple pH-shift method. We showed that curcumin could be successfully loaded into these LF-EGCG-HA nanoparticles (d = 145 nm). The encapsulation efficiency (86%) and loading capacity (5.8%) of curcumin within these nanoparticles were relatively high. Encapsulation improved the thermal, light, and storage stabilities of the curcumin. Moreover, the curcumin-loaded nanoparticles exhibited good redispersibility after dehydration. The in vitro digestion properties, cellular uptake, and anticancer effects of the curcumin-loaded nanoparticles were then explored. Compared to free curcumin, the bioaccessibility and cellular uptake of the curcumin were significantly improved after encapsulation in the nanoparticles. Furthermore, the nanoparticles significantly promoted the apoptosis of colorectal cancer cells. This study suggests that food-grade biopolymer nanoparticles can be used to improve the bioavailability and bioactivity of an important nutraceutical.

Lipid metabolism reprogramming in colorectal cancer

The hallmark feature of metabolic reprogramming is now considered to be widespread in many malignancies, including colorectal cancer (CRC). Of the gastrointestinal tumors, CRC is one of the most common with a high metastasis rate and long insidious period. The incidence and mortality of CRC has increased in recent years. Metabolic reprogramming also has a significant role in the development and progression of CRC, especially lipid metabolic reprogramming. Many studies have reported that lipid metabolism reprogramming is similar to the Warburg effect with typical features affecting tumor biology including proliferation, migration, local invasion, apoptosis, and other biological behaviors of cancer cells. Therefore, studying the role of lipid metabolism in the occurrence and development of CRC will increase our understanding of its pathogenesis, invasion, metastasis, and other processes and provide new directions for the treatment of CRC. In this paper, we mainly describe the molecular mechanism of lipid metabolism reprogramming and its important role in the occurrence and development of CRC. In addition, to provide reference for subsequent research and clinical diagnosis and treatment we also review the treatments of CRC that target lipid metabolism.

New Perspectives on Sleep Regulation by Tea: Harmonizing Pathological Sleep and Energy Balance under Stress

Sleep, a conservative evolutionary behavior of organisms to adapt to changes in the external environment, is divided into natural sleep, in a healthy state, and sickness sleep, which occurs in stressful environments or during illness. Sickness sleep plays an important role in maintaining energy homeostasis under an injury and promoting physical recovery. Tea, a popular phytochemical-rich beverage, has multiple health benefits, including lowering stress and regulating energy metabolism and natural sleep. However, the role of tea in regulating sickness sleep has received little attention. The mechanism underlying tea regulation of sickness sleep and its association with the maintenance of energy homeostasis in injured organisms remains to be elucidated. This review examines the current research on the effect of tea on sleep regulation, focusing on the function of tea in modulating energy homeostasis through sickness sleep, energy metabolism, and damage repair in model organisms. The potential mechanisms underlying tea in regulating sickness sleep are further suggested. Based on the biohomology of sleep regulation, this review provides novel insights into the role of tea in sleep regulation and a new perspective on the potential role of tea in restoring homeostasis from diseases.

The Crosstalk Between Signaling Pathways and Cancer Metabolism in Colorectal Cancer

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