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BACKGROUND: Lipid droplets (LDs) as major lipid storage organelles are recently reported to be innate immune hubs. Perilipin-3 (PLIN3) is indispensable for the formation and accumulation of LDs. Since cancer patients show dysregulated lipid metabolism, we aimed to elaborate the role of LDs-related PLIN3 in oral squamous cell carcinoma (OSCC). METHODS: PLIN3 expression patterns (n = 87), its immune-related landscape (n = 74) and association with B7-H2 (n = 51) were assessed by immunohistochemistry and flow cytometry. Real-time PCR, Western blot, Oil Red O assay, immunofluorescence, migration assay, spheroid-forming assay and flow cytometry were performed for function analysis. RESULTS: Spotted LDs-like PLIN3 staining was dominantly enriched in tumor cells than other cell types. PLIN3high tumor showed high proliferation index with metastasis potential, accompanied with less CD3+CD8+ T cells in peripheral blood and in situ tissue, conferring immunosuppressive microenvironment and shorter postoperative survival. Consistently, PLIN3 knockdown in tumor cells not only reduced LD deposits and tumor migration, but benefited for CD8+ T cells activation in co-culture system with decreased B7-H2. An OSCC subpopulation harbored PLIN3highB7-H2high tumor showed more T cells exhaustion, rendering higher risk of cancer-related death (95% CI 1.285-6.851). CONCLUSIONS: LDs marker PLIN3 may be a novel immunotherapeutic target in OSCC.
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Carcinoma de Células Escamosas , Neoplasias de Cabeza y Cuello , Neoplasias de la Boca , Humanos , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Linfocitos T CD8-positivos/metabolismo , Neoplasias de Cabeza y Cuello/metabolismo , Gotas Lipídicas/metabolismo , Neoplasias de la Boca/genética , Neoplasias de la Boca/metabolismo , Oncogenes , Perilipina-3/metabolismo , Carcinoma de Células Escamosas de Cabeza y Cuello/metabolismo , Microambiente TumoralRESUMEN
BACKGROUND: Renal cell cancer (RCC) is characterized by abnormal lipid accumulation. However, the specific mechanism by which such lipid deposition is eliminated remains unclear. Circular RNAs (circRNAs) widely regulate various biological processes, but the effect of circRNAs on lipid metabolism in cancers, especially clear cell renal cell carcinoma (ccRCC), remains poorly understood. METHODS: The downregulated circRNA, hsa_circ_0086414, was identified from high-throughput RNA-sequencing data of human ccRCC and pair-matched normal tissues. The target relationship between circRNA_0086414 and miR-661, and the transducer of ERBB2 (TOB2) was predicted using publicly available software programs and verified by luciferase reporter assays. The clinical prognostic value of TOB2 was evaluated by bioinformatic analysis. The expression levels of circRNA_0086414, miR-661, TOB2, and perilipin 3 (PLIN3) were measured by quantitative reverse-transcription polymerase chain reaction or western blot analysis. Cell Counting Kit-8, transwell assays, and xenograft models were employed to assess the biological behaviors of the hsa_circ_0086414/TOB2 axis. Oil Red staining and triglyceride assay was conducted to assess lipid deposition. RESULTS: Herein, we identified a downregulated circRNA, hsa_circ_0086414. Functionally, the restored hsa_circ_0086414 inhibited ccRCC proliferation, metastasis, and lipid accumulation in vitro and in vivo. Furthermore, the downregulated TOB2 predicted adverse prognosis and promoted cancer progression and lipid deposition in ccRCC. Mechanically, the binding of hsa_circ_0086414 to miR-661, as a miRNA sponge, upregulates the expression of TOB2, wielding an anti-oncogene effect. Importantly, the restored hsa_circ_0086414/TOB2 axis significantly contributed to the elimination of lipid deposition by inhibiting the lipid metabolism regulator PLIN3 in ccRCC cells. CONCLUSIONS: Our data highlight the importance of the hsa_circ_0086414/TOB2/PLIN3 axis as a tumor suppressor and lipid eliminator in ccRCC. The positive modulation of the hsa_circ_0086414/TOB2 axis might lead to the development of novel treatment strategies for ccRCC.
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Carcinoma de Células Renales , Carcinoma , Neoplasias Renales , MicroARNs , Humanos , Carcinoma de Células Renales/genética , Perilipina-3 , ARN Circular/genética , Neoplasias Renales/genética , Proliferación Celular/genética , Lípidos , MicroARNs/genética , Línea Celular Tumoral , Receptor ErbB-2RESUMEN
AIMS: To explore the accumulation of lipid droplets (LDs) and its relationship with lipid metabolism, and epithelial-mesenchymal transition (EMT) in the carcinogenesis processes in the oral cavity. METHODS: LDs were stained by oil red O. Forty-eight oral squamous cell carcinomas (OSCC), 78 oral potentially malignant disorders (OPMDs) and 25 normal tissue sections were included to explore the LDs surface protein caveolin-2 and perilipin-3, lipid metabolism-related molecule FABP5 and EMT biomarker E-cadherin expression by immunohistochemical staining. RESULTS: The accumulation of LDs was observed in OPMDs and OSCCs compared with normal tissues (p<0.05). In general, an increasing trend of caveolin-2, perilipin-3 and FABP5 expression was detected from the normal to OPMDs to OSCC groups (p<0.05). Additionally, caveolin-2, perilipin-3 and FABP5 expression were positively correlated with epithelial dysplasia in OPMDs, whereas E-cadherin positivity was negatively correlated with histopathological grade in both OPMDs and OSCC, respectively. A negative correlation of caveolin-2 (p<0.01, r =-0.1739), and FABP5 (p<0.01, r =-0.1880) with E-cadherin expression was detected. The caveolin-2 (p<0.0001, r=0.2641) and perilipin-3 (p<0.05, r=0.1408) staining was positively correlated with FABP5. Increased caveolin-2 expression was related to local recurrence and worse disease-free survival (p<0.05). CONCLUSION: In the oral epithelial carcinogenesis process, LDs begin to accumulate early in the precancerous stage. LDs may be the regulator of FABP5-associated lipid metabolism and may closely related to the process of EMT; caveolin-2 could be the main functional protein.
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Objective:To investigate the effect of estrogen-related receptor α (ESRRA)-mediated lipophagy on the proliferation and migration abilities of nasopharyngeal carcinoma cells.Methods:A total of 16 clinical samples diagnosed by pathology in the Affiliated Hospital of Nantong University from 2021 to 2023 were selected, including 8 normal nasopharyngeal mucosa tissues and 8 nasopharyngeal carcinoma tissues. Immortalized normal nasopharyngeal epithelial cell line NP69 and nasopharyngeal carcinoma cell lines C666-1, CNE2, TW03-EBV and TW03 were selected. The cell lines C666-1 and CNE2 were divided into the siR-NC group (transfected with small interfering RNA negative control sequence) and siR-ESRRA group (transfected with small interfering RNA against ESRRA gene). The relative expression levels of ESRRA were detected by Western blotting and immunohistochemical assay. EdU assay was used to detect the proliferation ability of C666-1 and CNE2 cells, and Transwell assay was used to detect the migration ability. Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the relative expression levels of ESRRA and perilipin 3 (PLIN3) mRNA. The formation of lipophagy in C666-1 and CNE2 cells was observed by transmission electron microscopy. The co-localization of LC3, PLIN3 and LAMP2 with lipid droplets labeling with Bodipy was detected by immunofluorescence assay. Dual-luciferase reporter gene assay was used to verify the targeting relationship between ESRRA and PLIN3.Results:The relative expression level of ESRRA in nasopharyngeal carcinoma tissues was higher than that in normal nasopharyngeal mucosa tissues(1.15±0.75 vs. 0.32±0.21, t = 3.02, P = 0.009). The relative expression level of ESRRA in nasopharyngeal carcinoma cell lines C666-1 (1.539±0.044), CNE2 (1.420±0.030), TW03-EBV (2.867±0.044), and TW03 (1.323±0.022) were higher than that in normal nasopharyngeal epithelial cell line NP69 (0.094±0.002), and the difference was statistically significant ( F = 34.08, P < 0.001).The results of EdU assay showed that the proportions of EdU labeled positive cells in CNE2 cells of siR-NC group and siR-ESRRA group were (70.44±4.06)% and (51.51±0.92)% ( t = 7.88, P = 0.001), and the proportions in C666-1 cells were (62.25±3.89)% and (54.91±0.27)% ( t = 3.26, P = 0.031). The results of Transwell assay showed that the number of migrating cells in CNE2 and C666-1 cells was less than that in siR-NC group [CNE2 cells: (181±7) cells vs. (261±21) cells; C666-1 cells: (201±16) cells vs. (256±7) cells], and the differences were statistically significant ( t = 6.30, P = 0.003; t = 5.43, P = 0.006). According to qRT-PCR results, the relative expression level of PLIN3 mRNA in the siR-ESRRA group was higher than that in the siR-NC group (CNE2 cells: 1.58±0.16 vs. 0.83±0.17, t = 5.59, P = 0.005; C666-1 cells: 1.37±0.12 vs. 1.06±0.06, t = 3.86, P = 0.018). The dual-luciferase reporter gene assay results indicated a targeted binding interaction between PLIN3 and ESRRA. Transmission electron microscopy observation showed that the lipid droplets in nasopharyngeal carcinoma cells increased and the binding to autophagosomes decreased after knockdown of ESRRA. The results of immunofluorescence assay demonstrated that, in contrast to the siR-NC group, there was a decrease in the co-localization of LC3 and LAMP2 and an increase in the co-localization of lipid droplets with PLIN3. Conclusions:ESRRA is highly expressed in nasopharyngeal carcinoma tissues and cells. As a transcription repressor, ESRRA may work to prevent PLIN3 from being transcribed, decrease lipid droplet stability, mediate lipophagy, and promote proliferation and migration of nasopharyngeal carcinoma cells.
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The most common type of intracranial malignancy is glioma. Although the current treatments are surgery, radiation and chemotherapy, the prognosis for patients with glioma is not promising. Therefore, it becomes critical to find an effective management. The literature shows that microRNA (miRNA) plays an important role in tumorigenesis and progression. Based on this, this study aimed to investigate the molecular mechanism of miR-525-5p in regulating the migration, invasion and proliferation of glioma cells. The TCGA database was used to identify perilipin 3 (PLIN3) differentially expressed in normal tissues and glioma tissues, and the CGGA and GEPIA databases were used to query that high expression of PLIN3 was associated with poor prognosis in glioma patients and Western blot experiments revealed that PLIN3 was highly expressed in glioma cells (P<0. 05) . The results of wound healing assay and Transwell invasion assay showed that knockdown or overexpression of PLIN3 respectively inhibited or promoted the migration and invasion of glioma cells (P < 0. 05) . Dual luciferase assays confirmed that PLIN3 could bind to miR-525-5p target. Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) showed that miR-525-5p expression was lower in LN229 and U251 glioma cells than in human astrocyte (HA) (P < 0. 05) . Transwell assay and 5-ethynyl-2-deoxyuridine (EdU) cell proliferation assay verified that down- or up-regulation of miR-525-5p could reverse the effects of overexpression or knockdown of PLIN3 on LN229 glioma cells (P<0. 05) . Taken together, miR-525-5p was able to regulate the migration, invasion and proliferation of glioma cells by targeting PLIN3.
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Metabolic homeostasis requires dynamic catabolic and anabolic processes. Autophagy, an intracellular lysosomal degradative pathway, can rewire cellular metabolism linking catabolic to anabolic processes and thus sustain homeostasis. This is especially relevant in the liver, a key metabolic organ that governs body energy metabolism. Autophagy's role in hepatic energy regulation has just begun to emerge and autophagy seems to have a much broader impact than what has been appreciated in the field. Though classically known for selective or bulk degradation of cellular components or energy-dense macromolecules, emerging evidence indicates autophagy selectively regulates various signaling proteins to directly impact the expression levels of metabolic enzymes or their upstream regulators. Hence, we review three specific mechanisms by which autophagy can regulate metabolism: A) nutrient regeneration, B) quality control of organelles, and C) signaling protein regulation. The plasticity of the autophagic function is unraveling a new therapeutic approach. Thus, we will also discuss the potential translation of promising preclinical data on autophagy modulation into therapeutic strategies that can be used in the clinic to treat common metabolic disorders.
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Lipid droplets (LDs) are dynamic organelles that undergo dynamic changes in response to changing cellular conditions. During nutrient depletion, LD numbers increase to protect cells against toxic fatty acids generated through autophagy and provide fuel for beta-oxidation. However, the precise mechanisms through which these changes are regulated have remained unclear. Here, we show that the small GTPase RalA acts downstream of autophagy to directly facilitate LD growth during nutrient depletion. Mechanistically, RalA performs this function through phospholipase D1 (PLD1), an enzyme that converts phosphatidylcholine (PC) to phosphatidic acid (PA) and that is recruited to lysosomes during nutrient stress in a RalA-dependent fashion. RalA inhibition prevents recruitment of the LD-associated protein perilipin 3, which is required for LD growth. Our data support a model in which RalA recruits PLD1 to lysosomes during nutrient deprivation to promote the localized production of PA and the recruitment of perilipin 3 to expanding LDs.
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Gotas Lipídicas/metabolismo , Nutrientes , Fosfolipasa D/metabolismo , Proteínas de Unión al GTP ral/metabolismo , Animales , Autofagia , Fibroblastos/metabolismo , Células HeLa , Humanos , Lisosomas/metabolismo , Ratones Noqueados , Perilipina-3/metabolismo , Ácidos Fosfatidicos/metabolismo , Triglicéridos/metabolismoRESUMEN
Intramuscular triglycerides (IMTG) are a key substrate during prolonged exercise, but little is known about the rate of IMTG resynthesis in the postexercise period. We investigated the hypothesis that the distribution of the lipid droplet (LD)-associated perilipin (PLIN) proteins is linked to IMTG storage following exercise. Fourteen elite male triathletes (27 ± 1 yr, 66.5 ± 1.3 mL·kg-1·min-1) completed 4 h of moderate-intensity cycling. During the first 4 h of recovery, subjects received either carbohydrate or H2O, after which both groups received carbohydrate. Muscle biopsies collected pre- and postexercise and 4 and 24 h postexercise were analyzed using confocal immunofluorescence microscopy for fiber type-specific IMTG content and PLIN distribution with LDs. Exercise reduced IMTG content in type I fibers (-53%, P = 0.002), with no change in type IIa fibers. During the first 4 h of recovery, IMTG content increased in type I fibers (P = 0.014), but was not increased more after 24 h, where it was similar to baseline levels in both conditions. During recovery the number of LDs labeled with PLIN2 (70%), PLIN3 (63%), and PLIN5 (62%; all P < 0.05) all increased in type I fibers. Importantly, the increase in LDs labeled with PLIN proteins only occurred at 24 h postexercise. In conclusion, IMTG resynthesis occurs rapidly in type I fibers following prolonged exercise in highly trained individuals. Furthermore, increases in IMTG content following exercise preceded an increase in the number of LDs labeled with PLIN proteins. These data, therefore, suggest that the PLIN proteins do not play a key role in postexercise IMTG resynthesis.
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Atletas , Gotas Lipídicas/metabolismo , Metabolismo de los Lípidos/fisiología , Lípidos/biosíntesis , Músculo Esquelético/fisiología , Perilipinas/metabolismo , Adulto , Ciclismo/fisiología , Biopsia , Ejercicio Físico/fisiología , Humanos , Masculino , Fibras Musculares de Contracción Lenta/fisiología , Perilipina-2/genética , Perilipina-2/metabolismo , Perilipina-3/genética , Perilipina-3/metabolismo , Perilipina-5/genética , Perilipina-5/metabolismo , Resistencia Física , Triglicéridos/metabolismo , Adulto JovenRESUMEN
Milk fat globules (MFGs), which are secreted by the epithelial cells of the lactating mammary glands, account for the most of the nutritional value of milk. They are enveloped by the milk fat globule membrane (MFGM), a complex structure consisting of three phospholipid membrane monolayers and containing various lipids. Depending on the origin of milk, specific proteins accounts for 5-70% of the MFGM mass. Proteome of MFGMs includes hundreds of proteins, with nine major components being adipophilin, butyrophilin, cluster of differentiation 36, fatty acid binding protein, lactadherin, mucin 1, mucin 15, tail-interacting protein 47 (TIP47), and xanthine oxidoreductase. Two of the MFGM components, adipophilin and TIP47, belong to the five-member perilipin family of lipid droplet proteins. Adipophilin is involved in the formation of cytoplasmic lipid droplets and secretion of MFGs. This protein is also related to the formation of other lipid droplets that exist in most cell types, playing an important role in the transport of lipids from ER to the surface of lipid droplets. TIP47 acts as a cytoplasmic sorting factor for mannose 6-phosphate receptors and is recruited to the MFGM. Therefore, both adipophilin and TIP47 are moonlighting proteins, each possessing several unrelated functions. This review focuses on the main functions and specific structural features of adipophilin and TIP47, analyzes similarities and differences of these proteins among different species, and describes these proteins in the context of other members of the perilipin family.Communicated by Ramaswamy H. Sarma.
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Glucolípidos/química , Glucolípidos/metabolismo , Glicoproteínas/química , Glicoproteínas/metabolismo , Gotas Lipídicas/química , Gotas Lipídicas/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Proteínas de la Leche/química , Proteínas de la Leche/metabolismo , Perilipina-2/química , Perilipina-2/metabolismo , Animales , Femenino , Regulación de la Expresión Génica , Glucolípidos/genética , Glicoproteínas/genética , Proteínas Intrínsecamente Desordenadas/química , Proteínas Intrínsecamente Desordenadas/genética , Proteínas Intrínsecamente Desordenadas/metabolismo , Lactancia , Metabolismo de los Lípidos , Lípidos , Proteínas de la Membrana/genética , Proteínas de la Leche/genética , Familia de Multigenes , Perilipina-2/genética , Unión Proteica , Relación Estructura-ActividadRESUMEN
KEY POINTS: The lipid droplet (LD)-associated perilipin (PLIN) proteins promote intramuscular triglyceride (IMTG) storage, although whether the abundance and association of the PLIN proteins with LDs is related to the diverse lipid storage in muscle between trained and sedentary individuals is unknown. We show that lipid infusion augments IMTG content in type I fibres of both trained and sedentary individuals. Most importantly, despite there being no change in PLIN protein content, lipid infusion did increase the number of LDs connected with PLIN proteins in trained individuals only. We conclude that trained individuals are able to redistribute the pre-existing pool of PLIN proteins to an expanded LD pool during lipid infusion and, via this adaptation, may support the storage of fatty acids in IMTG. ABSTRACT: Because the lipid droplet (LD)-associated perilipin (PLIN) proteins promote intramuscular triglyceride (IMTG) storage, we investigated the hypothesis that differential protein content of PLINs and their distribution with LDs may be linked to the diverse lipid storage in muscle between trained and sedentary individuals. Trained (n = 11) and sedentary (n = 10) subjects, matched for age, sex and body mass index, received either a 6 h lipid or glycerol infusion in the setting of a concurrent hyperinsulinaemic-euglycaemic clamp. Sequential muscle biopsies (0, 2 and 6 h) were analysed using confocal immunofluorescence microscopy for fibre type-specific IMTG content and PLIN associations with LDs. In both groups, lipid infusion increased IMTG content in type I fibres (trained: +62%, sedentary: +79%; P < 0.05) but did not affect PLIN protein content. At baseline, PLIN2 (+65%), PLIN3 (+105%) and PLIN5 (+53%; all P < 0.05) protein content was higher in trained compared to sedentary individuals. In trained individuals, lipid infusion increased the number of LDs associated with PLIN2 (+27%), PLIN3 (+73%) and PLIN5 (+40%; all P < 0.05) in type I fibres. By contrast, in sedentary individuals, lipid infusion only increased the number of LDs not associated with PLIN proteins. Acute free fatty acid elevation therefore induces a redistribution of PLIN proteins to an expanded LD pool in trained individuals only and this may be part of the mechanism that enables fatty acids to be stored in IMTG.
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Ejercicio Físico/fisiología , Lípidos/farmacología , Músculo Esquelético/fisiología , Perilipinas/fisiología , Adulto , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
Lipid accumulation in macrophages contributes to atherosclerosis. Within macrophages, lipids are stored in lipid droplets (LDs); perilipin-2 and perilipin-3 are the main LD-associated proteins. Postprandial triglyceride (TG)-rich lipoproteins induce LD accumulation in macrophages. The role of postprandial lipoproteins in perilipin-2 and perilipin-3 regulation was studied. TG-rich lipoproteins (TRLs) induced the levels of intracellular TGs, LDs and perilipin-2 protein expression in THP-1 macrophages and in Apoe(-/-) mice bone-marrow-derived macrophages with low and high basal levels of TGs. Perilipin-3 was only synthesized in mice macrophages with low basal levels of TGs. The regulation was dependent on the fatty acid composition of the lipoproteins; monounsaturated and polyunsaturated fatty acids (PUFAs) more strongly attenuated these effects compared with saturated fatty acids. In THP-1 macrophages, immunofluorescence microscopy and freeze-fracture immunogold labeling indicated that the lipoproteins translocated perilipin-3 from the cytoplasm to the LD surface; only the lipoproteins that were rich in PUFAs suppressed this effect. Chemical inhibition showed that lipoproteins induced perilipin-2 protein expression through the peroxisome proliferator-activated nuclear receptor (PPAR) PPARα and PPARγ pathways. Overall, our data indicate that postprandial TRLs may be involved in atherosclerotic plaque formation through the regulation of perilipin-2 and perilipin-3 proteins in macrophages. Because the fatty acid composition of the lipoproteins is dependent on the type of fat consumed, the ingestion of olive oil, which is rich in monounsaturated fatty acids, and fish oil, which is rich in omega-3 fatty acids, can be considered a good nutritional strategy to reduce the risk of atherosclerosis by LD-associated proteins decrease.