FOXM1-mediated activation of phospholipase D1 promotes lipid droplet accumulation and reduces ROS to support paclitaxel resistance in metastatic cancer cells

ROS: A "booster" for chronic inflammation and tumor metastasis

Reactive oxygen species (ROS) are a group of highly active molecules produced by normal cellular metabolism and play a crucial role in the human body. In recent years, researchers have increasingly discovered that ROS plays a vital role in the progression of chronic inflammation and tumor metastasis. The inflammatory tumor microenvironment established by chronic inflammation can induce ROS production through inflammatory cells. ROS can then directly damage DNA or indirectly activate cellular signaling pathways to promote tumor metastasis and development, including breast cancer, lung cancer, liver cancer, colorectal cancer, and so on. This review aims to elucidate the relationship between ROS, chronic inflammation, and tumor metastasis, explaining how chronic inflammation can induce tumor metastasis and how ROS can contribute to the evolution of chronic inflammation toward tumor metastasis. Interestingly, ROS can have a "double-edged sword" effect, promoting tumor metastasis in some cases and inhibiting it in others. This article also highlights the potential applications of ROS in inhibiting tumor metastasis and enhancing the precision of tumor-targeted therapy. Combining ROS with nanomaterials strategies may be a promising approach to enhance the efficacy of tumor treatment.

Forkhead box M1 mediates metabolic reprogramming in human colorectal cancer cells

Metabolic reprogramming is recognized as a hallmark of cancer, enabling cancer cells to acquire essential biomolecules for cell growth, often characterized by upregulated glycolysis and/or fatty acid synthesis-related genes. The transcription factor forkhead box M1 (FOXM1) has been implicated in various cancers, contributing significantly to their development, including colorectal cancer (CRC), a major global health concern. Despite FOXM1's established role in cancer, its specific involvement in the Warburg effect and fatty acid biosynthesis in CRC remains unclear. We analyzed The Cancer Genome Atlas (TCGA) Colonic Adenocarcinoma and Rectal Adenocarcinoma (COADREAD) datasets to derive the correlation of the expression levels between FOXM1 and multiple genes and the survival prognosis based on FOXM1 expression. Using two human CRC cell lines, HT29 and HCT116, we conducted RNAi or plasmid transfection procedures, followed by a series of assays, including RNA extraction, quantitative real-time polymerase chain reaction, Western blot analysis, cell metabolic assay, glucose uptake assay, Oil Red O staining, cell viability assay, and immunofluorescence analysis. Higher expression levels of FOXM1 correlated with a poorer survival prognosis, and the expression of FOXM1 was positively correlated with glycolysis-related genes SLC2A1 and LDHA, de novo lipogenesis-related genes ACACA and FASN, and MYC. FOXM1 appeared to modulate AKT/mammalian target of rapamycin (mTOR) signaling, the expression of c-Myc, proteins related to glycolysis and fatty acid biosynthesis, and glucose uptake, as well as extracellular acidification rate in HT29 and HCT116 cells. In summary, FOXM1 plays a regulatory role in glycolysis, fatty acid biosynthesis, and cellular energy consumption, thereby influencing CRC cell growth and patient prognosis.NEW & NOTEWORTHY Transcription factor forkhead box M1 (FOXM1) regulates glycolysis, fatty acid biosynthesis, and cellular energy consumption, which, together, controls cell growth and patient prognosis in colorectal cancer (CRC).

Targeting lipid biosynthesis on the basis of conventional treatments for clear cell renal cell carcinoma: A promising therapeutic approach

A variety of cancer cells exhibit dysregulated lipid metabolism, characterized by excessive intracellular lipid accumulation, and clear cell renal cell carcinoma (ccRCC) is the most typical disease with these characteristics. As the most common malignancy of all renal cell carcinomas (RCCs), ccRCC is typically characterized by a large accumulation of lipids and glycogen in the cytoplasm and a nucleus that is squeezed by the accumulated lipid droplets and localized to the marginal areas within the cytoplasm. This lipid accumulation has been found to be critically involved in the maintenance of malignant features observed in various cancers. Firstly, it maintains the persistent proliferative and metastasis properties of cancer cells. Secondly, it acts as a buffer against lipid peroxidation, preventing lipid peroxidation-induced ferroptosis. Moreover, lipids can diminish the sensitivity of cancer cells to radiotherapy. As ccRCC is a type of cancer with high lipid synthesis, targeting lipid synthesis-related genes in cancer cells may be a promising therapeutic modality for single treatment or in combination with radiotherapy, chemotherapy, and immunotherapy. This may revolutionize the choice of treatment modality for ccRCC patients. In this review, we concentrate on the current status and progress of research on lipid biosynthesis in ccRCC and the potential applications of targeting lipid synthesis to treat ccRCC. At last, we propose perspective and future research directions for targeting inhibition of lipid biosynthesis in combination with conventional therapeutic approaches for the treatment of ccRCC, which will help to evolve the therapeutic model.

Fatty acids in cancer chemoresistance

Despite the remarkable clinical success of immunotherapy and molecular targeted therapy in patients with advanced tumors, chemotherapy remains the most commonly used treatment for most tumor patients. Chemotherapy drugs effectively inhibit tumor cell proliferation and survival through their remarkable mechanisms. However, tumor cells often develop severe intrinsic and acquired chemoresistance under chemotherapy stress, limiting the effectiveness of chemotherapy and leading to treatment failure. Growing evidence suggests that alterations in lipid metabolism may be implicated in the development of chemoresistance in tumors. Therefore, in this review, we provide a comprehensive overview of fatty acid metabolism and its impact on chemoresistance mechanisms. Additionally, we discuss the potential of targeting fatty acid metabolism as a therapeutic strategy to overcome drug resistance.

Inhibition of phospholipase D1 ameliorates hepatocyte steatosis and non-alcoholic fatty liver disease

Background & Aims

Phospholipase D1 (PLD1), a phosphatidylcholine-hydrolysing enzyme, is involved in cellular lipid metabolism. However, its involvement in hepatocyte lipid metabolism and consequently non-alcoholic fatty liver disease (NAFLD) has not been explicitly explored.

Methods

NAFLD was induced in hepatocyte-specific Pld1 knockout (Pld1(H)-KO) and littermate Pld1 ^flox/flox (Pld1-Flox) control mice feeding a high-fat diet (HFD) for 20 wk. Changes of the lipid composition in the liver were compared. Alpha mouse liver 12 (AML12) cells and mouse primary hepatocytes were incubated with oleic acid or sodium palmitate in vitro to explore the role of PLD1 in the development of hepatic steatosis. Hepatic PLD1 expression was evaluated in liver biopsy samples in patients with NAFLD.

Results

PLD1 expression levels were increased in the hepatocytes of patients with NAFLD and HFD-fed mice. Compared with Pld1-Flox mice, Pld1(H)-KO mice exhibited decreased plasma glucose and lipid levels as well as lipid accumulation in liver tissues after HFD feeding. Transcriptomic analysis showed that hepatocyte-specific deficiency of PLD1 decreased Cd36 expression in steatosis liver tissues, which was confirmed at the protein and gene levels. In vitro, specific inhibition of PLD1 with VU0155069 or VU0359595 decreased CD36 expression and lipid accumulation in oleic acid- or sodium palmitate-treated AML12 cells or primary hepatocytes. Inhibition of hepatocyte PLD1 significantly altered lipid composition, especially phosphatidic acid and lysophosphatidic acid levels in liver tissues with hepatic steatosis. Furthermore, phosphatidic acid, the downstream product of PLD1, increased the expression levels of CD36 in AML12 cells, which was reversed by a PPARγ antagonist.

Conclusions

Hepatocyte-specific Pld1 deficiency ameliorates lipid accumulation and NAFLD development by inhibiting the PPARγ/CD36 pathway. PLD1 may be a new target for the treatment of NAFLD.

Impact and implications

The involvement of PLD1 in hepatocyte lipid metabolism and NAFLD has not been explicitly explored. In this study, we found that the inhibition of hepatocyte PLD1 exerted potent protective effects against HFD-induced NAFLD, which were attributable to a reduction in PPARγ/CD36 pathway-mediated lipid accumulation in hepatocytes. Targeting hepatocyte PLD1 may be a new target for the treatment of NAFLD.

Stearoyl-CoA Desaturases1 Accelerates Non-Small Cell Lung Cancer Metastasis by Promoting Aromatase Expression to Improve Estrogen Synthesis

Metastases contribute to the low survival rate of non-small cell lung cancer (NSCLC) patients. Targeting lipid metabolism for anticancer therapies is attractive. Accumulative evidence shows that stearoyl-CoA desaturases1 (SCD1), a key enzyme in lipid metabolism, enables tumor metastasis and the underlying mechanism remains unknown. In this study, immunohistochemical staining of 96 clinical specimens showed that the expression of SCD1 was increased in tumor tissues (p < 0.001). SCD1 knockdown reduced the migration and invasion of HCC827 and PC9 cells in transwell and wound healing assays. Aromatase (CYP19A1) knockdown eliminated cell migration and invasion caused by SCD1 overexpression. Western blotting assays demonstrated that CYP19A1, along with β-catenin protein levels, was reduced in SCD1 knocked-down cells, and estrogen concentration was reduced (p < 0.05) in cell culture medium measured by enzyme-linked immunosorbent assay. SCD1 overexpression preserving β-catenin protein stability was evaluated by coimmunoprecipitation and Western blotting. The SCD1 inhibitor A939572, and a potential SCD1 inhibitor, grape seed extract (GSE), significantly inhibited cell migration and invasion by blocking SCD1 and its downstream β-catenin, CYP19A1 expression, and estrogen concentration. In vivo tumor formation assay and a tail vein metastasis model indicated that knockdown of SCD1 blocked tumor growth and metastasis. In conclusion, SCD1 could accelerate metastasis by maintaining the protein stability of β-catenin and then promoting CYP19A1 transcription to improve estrogen synthesis. SCD1 is expected to be a promised therapeutic target, and its novel inhibitor, GSE, has great therapeutic potential in NSCLC.

Phospholipase D and cancer metastasis: A focus on exosomes

In mammals, phospholipase D (PLD) enzymes involve 6 isoforms, of which only three have established lipase activity to produce the signaling lipid phosphatidic acid (PA). This phospholipase activity has been postulated to contribute to cancer progression for over three decades now, but the exact mechanisms involved have yet to be uncovered. Indeed, using various models, an altered PLD activity has been proposed altogether to increase cell survival rate, promote angiogenesis, boost rapamycin resistance, and favor metastasis. Although for some part, the molecular pathways by which this increase in PA is pro-oncogenic are partially known, the pleiotropic functions of PA make it quite difficult to distinguish which among these simple signaling pathways is responsible for each of these PLD facets. In this review, we will describe an additional potential contribution of PA generated by PLD1 and PLD2 in the biogenesis, secretion, and uptake of exosomes. Those extracellular vesicles are now viewed as membrane vehicles that carry informative molecules able to modify the fate of receiving cells at distance from the original tumor to favor homing of metastasis. The perspectives for a better understanding of these complex role of PLDs will be discussed.

Loss of EMP1 promotes the metastasis of human bladder cancer cells by promoting migration and conferring resistance to ferroptosis through activation of PPAR gamma signaling

Metastasis, in which cancer cells detach from the original site and colonise other organs, is the primary cause of death induced by bladder cancer (BCa). Epithelial Membrane Protein 1 (EMP1) is dysregulated in many human cancers, and its clinical significance and biological function in diseases, including BCa, are largely unclear. Here, we demonstrated that EMP1 was downregulated in BCa cells. The deficiency of EMP1 promotes migration and confers resistance to ferroptosis/oxidative stress in BCa cells, favouring tumour cell metastasis. Mechanistically, we demonstrated that EMP1 deficiency enhanced tumour metastasis by increasing PPARG expression and promoting its activation, leading to upregulation of pFAK(Y397) and SLC7A11, which promoted cell migration and anti-ferroptotic cell death respectively. Moreover, we found EMP1-deficient sensitized cells to PPARG's ligand, which effect are metastatic phenotype promoted and could be mitigated by FABP4 knockdown. In conclusion, our study, for the first time, reveals that EMP1 deficiency promotes BCa cell migration and confers resistance to ferroptosis/oxidative stress, thus promoting metastasis of BCa via PPARG. These results revealed a novel role of EMP1-mediated PPARG in bladder cancer metastasis.