Suppressed PLIN3 frequently occurs in prostate cancer, promoting docetaxel resistance via intensified autophagy, an event reversed by chloroquine

Lipid droplet - organelle crosstalk and its implication in cancer

Lipid droplets (LDs) store lipids in cells, provide phospholipids for membrane synthesis, and maintain the intracellular balance of energy and lipid metabolism. Undoubtedly, the crosstalk between LDs and other organelles is the foundation for performing functions. Many studies indicate that LDs promote tumor progression. LD accumulation has been observed in a variety of cancers, and high LD content is associated with malignant phenotype and poor prognosis of cancers. In this paper, we summarized the intimate crosstalk between LDs and intracellular organelles, including endoplasmic reticulum (ER), mitochondria, lysosomes and peroxisomes, and addressed the effects of LD-organelle crosstalk on cancer initiation and progression. We also integrated the changes of LD-organelle interactions in cancers to provide an insightful knowledge for cancer therapeutics.

Transcription Factor FOSL1 Promotes Cisplatin Resistance in Non-Small Cell Lung Cancer Cells by Modulating the Wnt3a/β-Catenin Signaling through Upregulation of PLIN3 Expression

BACKGROUND

Lung adenocarcinoma (LUAD) is the most prevalent histological subtype of lung cancer, accounting for 45.3% of all cases and serving as a major cause of cancer-related mortality. Although cisplatin (DDP) is a cornerstone in LUAD therapy, its efficacy is often compromised by resistance, leading to therapeutic failure and poor patient outcomes. Lipid metabolism and associated proteins, such as perilipin 3 (PLIN3), have been increasingly implicated in cancer progression and chemoresistance. However, the precise mechanisms through which PLIN3 contributes to cisplatin (DDP) resistance in LUAD remain poorly understood.

METHODS

To investigate the role of PLIN3 in DDP resistance, its expression in LUAD tissues and its correlation with patient prognosis were analyzed using bioinformatics databases and validated through clinical sample analysis. The effects of PLIN3 knockdown and overexpression on DDP resistance and Wnt3a/β-catenin signaling were assessed using quantitative real-time PCR (qPCR), western blotting, cytotoxicity assays, and colony formation assays. Bioinformatics screening identified FOS-like antigen 1 (FOSL1) as a transcription factor positively correlated with PLIN3, and its involvement in DDP resistance was further examined both in vitro and in vivo.

RESULTS

PLIN3 expression is significantly elevated in LUAD tissues and correlates with poor overall survival. In LUAD cells, PLIN3 overexpression enhanced DDP resistance by upregulating Wnt3a expression and promoting β-catenin nuclear translocation. Bioinformatics analysis identified FOSL1 as a key transcription factor regulating PLIN3 expression. Experimental validation confirmed that FOSL1 directly binds to the PLIN3 promoter, activating the Wnt3a/β-catenin pathway and promoting DDP resistance. Knockdown of PLIN3 or inhibition of Wnt3a signaling reversed the effects of FOSL1 overexpression on DDP resistance.

CONCLUSION

This study demonstrates that PLIN3 contributes to DDP resistance in LUAD by activating the Wnt3a/β-catenin signaling pathway, with FOSL1 acting as a critical upstream regulator. Targeting the FOSL1/PLIN3/Wnt/β-catenin axis may provide a promising therapeutic strategy for overcoming chemoresistance in LUAD.

The Role of PLIN3 in Prognosis and Tumor-Associated Macrophage Infiltration: A Pan-Cancer Analysis

Background

Nucleolar and spindle-associated protein 1 (PLIN3), a member of the perilipin family, plays a critical role in lipid droplet dynamics and is implicated in promoting tumor progression across several cancers. However, its influence on the tumor immune microenvironment and its potential as a prognostic indicator regarding immunotherapy responses have yet to be systematically evaluated. This study leverages data retrieved from multiple databases to address these questions.

Methods

PLIN3 mRNA and protein expressions were analyzed across a diverse range of normal and cancerous tissues, utilizing data retrieved from multiple databases. The potential of PLIN3 as a diagnostic and prognostic biomarker in cancers was assessed. Advanced computational algorithms were employed to examine the impact of PLIN3 on immune cell infiltration. The association between PLIN3 expression and the presence of M2 macrophages was validated through analyses incorporating bulk and single-cell transcriptomics, spatial transcriptomics, and multicolor fluorescence staining techniques. Furthermore, the effects of PLIN3 on tumor malignancy and growth were investigated in vitro in lung adenocarcinoma (LUAD) cells. Potential compounds targeting PLIN3 were identified using the Connectivity Map (cMap) web tool, and their efficacy was further assessed through molecular docking.

Results

PLIN3 was predominantly upregulated in various cancers, correlating with adverse prognostic outcomes. A strong positive association was observed between PLIN3 levels and M2 macrophage infiltration in several cancer types, establishing it as a potential pan-cancer marker for M2 macrophage presence. This was confirmed by integrative multi-omics analysis and multiple fluorescence staining. Additionally, PLIN3 knockdown in LUAD cells diminished their malignant traits, resulting in decreased proliferation and migration. In LUAD, clofibrate was identified as a potential inhibitor of PLIN3's pro-oncogenic functions.

Conclusion

PLIN3 may serve as a potential biomarker and oncogene, particularly in LUAD. It plays a key role in mediating M2 macrophage infiltration in various cancers and presents a promising immunotherapeutic target.

Docosahexaenoic acid enhances the treatment efficacy for castration-resistant prostate cancer by inhibiting autophagy through Atg4B inhibition

Autophagy induction in cancer is involved in cancer progression and the acquisition of resistance to anticancer agents. Therefore, autophagy is considered a potential therapeutic target in cancer therapy. In this study, we found that long-chain fatty acids (LCFAs) have inhibitory effects on Atg4B, which is essential for autophagosome formation, through screening based on the pharmacophore of 21f, a recently developed Atg4B inhibitor. Among these fatty acids, docosahexaenoic acid (DHA), a polyunsaturated fatty acid, exhibited the most potent Atg4B inhibitory activity. DHA inhibited autophagy induced by androgen receptor signaling inhibitors (ARSI) in LNCaP and 22Rv1 prostate cancer cells and significantly increased apoptotic cell death. Furthermore, we investigated the effect of DHA on resistance to ARSI by establishing darolutamide-resistant prostate cancer 22Rv1 (22Rv1/Dar) cells, which had developed resistance to darolutamide, a novel ARSI. At baseline, 22Rv1/Dar cells showed a higher autophagy level than parental 22Rv1 cells. DHA significantly suppressed Dar-induced autophagy and sensitized 22Rv1/Dar cells by inducing apoptotic cell death through mitochondrial dysfunction. These results suggest that DHA supplementation may improve prostate cancer therapy with ARSI.

Lipid droplets-related Perilipin-3: potential immune checkpoint and oncogene in oral squamous cell carcinoma

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.

Molecular panorama of therapy resistance in prostate cancer: a pre-clinical and bioinformatics analysis for clinical translation

Prostate cancer (PCa) is a malignant disorder of prostate gland being asymptomatic in early stages and high metastatic potential in advanced stages. The chemotherapy and surgical resection have provided favourable prognosis of PCa patients, but advanced and aggressive forms of PCa including CRPC and AVPC lack response to therapy properly, and therefore, prognosis of patients is deteriorated. At the advanced stages, PCa cells do not respond to chemotherapy and radiotherapy in a satisfactory level, and therefore, therapy resistance is emerged. Molecular profile analysis of PCa cells reveals the apoptosis suppression, pro-survival autophagy induction, and EMT induction as factors in escalating malignant of cancer cells and development of therapy resistance. The dysregulation in molecular profile of PCa including upregulation of STAT3 and PI3K/Akt, downregulation of STAT3, and aberrant expression of non-coding RNAs are determining factor for response of cancer cells to chemotherapy. Because of prevalence of drug resistance in PCa, combination therapy including co-utilization of anti-cancer drugs and nanotherapeutic approaches has been suggested in PCa therapy. As a result of increase in DNA damage repair, PCa cells induce radioresistance and RelB overexpression prevents irradiation-mediated cell death. Similar to chemotherapy, nanomaterials are promising for promoting radiosensitivity through delivery of cargo, improving accumulation in PCa cells, and targeting survival-related pathways. In respect to emergence of immunotherapy as a new tool in PCa suppression, tumour cells are able to increase PD-L1 expression and inactivate NK cells in mediating immune evasion. The bioinformatics analysis for evaluation of drug resistance-related genes has been performed.

Silencing of Perilipin 3 Inhibits Lung Adenocarcinoma Cell Immune Resistance by Regulating the Transcription of PD-L1 Through c-Myc

BACKGROUND

Perilipin 3 (PLIN3), a lipid droplet-associated protein, is found to be highly expressed in human cancers. This study aimed to investigate the biological functions and underlying mechanism of PLIN3 in lung adenocarcinoma (LUAD).

METHODS

To analyse PLIN3 expression in normal and cancerous tissues, relevance between PLIN3 expression and survival prognosis, and to predict the pathways related to PLIN3, bioinformatic analysis was performed. In A549 and H1299 cells, qRT-PCR or western blotting was used to determine mRNA/protein expression of PLIN3, PD-L1, and c-Myc. In A549 and H1299 cells, CCK-8 assay, EdU, and flow cytometry were used to assess cell viability, proliferation, and apoptosis. Chip and luciferase reporter assays were performed to verify the binding of PD-L1 with c-Myc. The functions of PLIN3 were examined in vivo in a xenograft tumor model.

RESULTS

In LUAD tissues and cells, PLIN3 expression was downregulated. A shorter survival time was observed in patients with high PLIN3 expression than in patients with low PLIN3 expression. Silencing of PLIN3 inhibited cell proliferation, PD-L1 expression, and Myc pathway, as well as induced apoptosis in LUAD cells. c-Myc acts as a transcription factor of PD-L1. Moreover, the inhibitory actions of PLIN3 silencing on c-Myc and PD-L1 expression as well as cell proliferation and stimulatory action of PLIN3 silencing on cell apoptosis were reversed by c-Myc overexpression. In vivo, PLIN3 silencing inhibited the growth of xenograft tumour and reduced PLIN3, PD-L1, and c-Myc protein expression.

CONCLUSION

Silencing of PLIN3 inhibited tumour growth by regulating the Myc/PD-L1 pathway.

Targeting the ATF6-Mediated ER Stress Response and Autophagy Blocks Integrin-Driven Prostate Cancer Progression

Prostate cancer progression to the lethal metastatic castration-resistant phenotype (mCRPC) is driven by αv integrins and is associated with Golgi disorganization and activation of the ATF6 branch of unfolded protein response (UPR). Overexpression of integrins requires N-acetylglucosaminyltransferase-V (MGAT5)-mediated glycosylation and subsequent cluster formation with Galectin-3 (Gal-3). However, the mechanism underlying this altered glycosylation is missing. For the first time, using HALO analysis of IHC, we found a strong association of integrin αv and Gal-3 at the plasma membrane (PM) in primary prostate cancer and mCRPC samples. We discovered that MGAT5 activation is caused by Golgi fragmentation and mislocalization of its competitor, N-acetylglucosaminyltransferase-III, MGAT3, from Golgi to the endoplasmic reticulum (ER). This was validated in an ethanol-induced model of ER stress, where alcohol treatment in androgen-refractory PC-3 and DU145 cells or alcohol consumption in patient with prostate cancer samples aggravates Golgi scattering, activates MGAT5, and enhances integrin expression at PM. This explains known link between alcohol consumption and prostate cancer mortality. ATF6 depletion significantly blocks UPR and reduces the number of Golgi fragments in both PC-3 and DU145 cells. Inhibition of autophagy by hydroxychloroquine (HCQ) restores compact Golgi, rescues MGAT3 intra-Golgi localization, blocks glycan modification via MGAT5, and abrogates delivery of Gal-3 to the cell surface. Importantly, the loss of Gal-3 leads to reduced integrins at PM and their accelerated internalization. ATF6 depletion and HCQ treatment synergistically decrease integrin αv and Gal-3 expression and temper orthotopic tumor growth and metastasis.

IMPLICATIONS

Combined ablation of ATF6 and autophagy can serve as new mCRPC therapeutic.

Challenges in Pharmacological Intervention in Perilipins (PLINs) to Modulate Lipid Droplet Dynamics in Obesity and Cancer

Perilipins (PLINs) are the most abundant proteins in lipid droplets (LD). These LD-associated proteins are responsible for upgrading LD from inert lipid storage structures to fully functional organelles, fundamentally integrated in the lipid metabolism. There are five distinct perilipins (PLIN1-5), each with specific expression patterns and metabolic activation, but all capable of regulating the activity of lipases on LD. This plurality creates a complex orchestrated mechanism that is directly related to the healthy balance between lipogenesis and lipolysis. Given the essential role of PLINs in the modulation of the lipid metabolism, these proteins can become interesting targets for the treatment of lipid-associated diseases. Since reprogrammed lipid metabolism is a recognized cancer hallmark, and obesity is a known risk factor for cancer and other comorbidities, the modulation of PLINs could either improve existing treatments or create new opportunities for the treatment of these diseases. Even though PLINs have not been, so far, directly considered for pharmacological interventions, there are many established drugs that can modulate PLINs activity. Therefore, the aim of this study is to assess the involvement of PLINs in diseases related to lipid metabolism dysregulation and whether PLINs can be viewed as potential therapeutic targets for cancer and obesity.

Paclitaxel and docetaxel resistance in prostate cancer: Molecular mechanisms and possible therapeutic strategies

Prostate cancer is among most malignant tumors around the world and this urological tumor can be developed as result of genomic mutations and their accumulation during progression towards advanced stage. Due to lack of specific symptoms in early stages of prostate cancer, most cancer patients are diagnosed in advanced stages that tumor cells display low response to chemotherapy. Furthermore, genomic mutations in prostate cancer enhance the aggressiveness of tumor cells. Docetaxel and paclitaxel are suggested as well-known compounds for chemotherapy of prostate tumor and they possess a similar function in cancer therapy that is based on inhibiting depolymerization of microtubules, impairing balance of microtubules and subsequent delay in cell cycle progression. The aim of current review is to highlight mechanisms of paclitaxel and docetaxel resistance in prostate cancer. When oncogenic factors such as CD133 display upregulation and PTEN as tumor-suppressor shows decrease in expression, malignancy of prostate tumor cells enhances and they can induce drug resistance. Furthermore, phytochemicals as anti-tumor compounds have been utilized in suppressing chemoresistance in prostate cancer. Naringenin and lovastatin are among the anti-tumor compounds that have been used for impairing progression of prostate tumor and enhancing drug sensitivity. Moreover, nanostructures such as polymeric micelles and nanobubbles have been utilized in delivery of anti-tumor compounds and decreasing risk of chemoresistance development. These subjects are highlighted in current review to provide new insight for reversing drug resistance in prostate cancer.

Epidemiological, Clinical, and Genomic Profile in Head and Neck Cancer Patients and Their Families

Inherited cancer predisposition genes are described as risk factors in head and neck cancer (HNC) families. To explore the clinical and epidemiological data and their association with a family history of cancer, we recruited 74 patients and 164 relatives affected by cancer. The germline copy number alterations were evaluated in 18 patients using array comparative genomic hybridization. Two or more first-degree relatives with HNC, tobacco-associated tumor sites (lung, esophagus, and pancreas), or other related tumors (breast, colon, kidney, bladder, cervix, stomach carcinomas, and melanoma) were reported in 74 families. Ten index patients had no exposure to any known risk factors. Family members presented tumors of 19 topographies (30 head and neck, 26 breast, 21 colon). In first-degree relatives, siblings were frequently affected by cancer (n = 58, 13 had HNC). Breast cancer (n = 21), HNC (n = 19), and uterine carcinoma (n = 15) were commonly found in first-degree relatives and HNC in second-degree relatives (n = 11). Nineteen germline genomic imbalances were detected in 13 patients; three presented gains of WRD genes. The number of HNC patients, the degree of kinship, and the tumor types detected in each relative support the role of heredity in these families. Germline alterations may potentially contribute to cancer development.

Focusing on the Role of Natural Products in Overcoming Cancer Drug Resistance: An Autophagy-Based Perspective

Autophagy is a critical cellular adaptive response in tumor formation. Nutritional deficiency and hypoxia exacerbate autophagic flux in established malignancies, promoting tumor cell proliferation, migration, metastasis, and resistance to therapeutic interventions. Pro-survival autophagy inhibition may be a promising treatment option for advanced cancer. Furthermore, excessive or persistent autophagy is cytotoxic, resulting in tumor cell death. Targeted autophagy activation has also shown significant promise in the fight against tumor drug resistance. Several research groups have examined the ability of natural products (NPs) such as alkaloids, terpenoids, polyphenols, and anthraquinones to serve as autophagy inhibitors or activators. The data support the capacity of NPs that promote lethal autophagy or inhibit pro-survival autophagy from being employed against tumor drug resistance. This paper discusses the potential applications of NPs that regulate autophagy in the fight against tumor drug resistance, some limitations of the current studies, and future research needs and priorities.

Lipophagy-related protein perilipin-3 (PLIN3) and resistance of prostate cancer to radiotherapy

PURPOSE

Radiotherapy is a principal treatment modality for localized and locally advanced prostate cancer (PCa). Metabolic alterations, including lipid metabolism, may reduce treatment efficacy resulting in tumor relapse and poor therapeutic outcome. In the current study, we investigated the role of the lipophagy-related protein perilipin-3 (PLIN3) and the lysosomal acid lipase (LAL) in PCa response to radiotherapy.

METHODS AND MATERIALS

We explored the in vitro and xenograft (in NOD.SCID and R2G2 mice) response to radiation of either PLIN3-depleted or LAL-depleted hormone-refractory (DU145, PC3), and hormone-responsive 22Rv1 PCa cell lines. Moreover, we evaluated the clinical role of PLIN3 and LAL protein expression in a series of PCa tissue specimens from patients treated with radical radiotherapy.

RESULTS

In vitro and in vivo experiments showed reduced proliferation and strong radiosensitization of all studied PCa cell lines upon PLIN3 depletion. In vivo experiments demonstrated the significantly augmented radiotherapy efficacy upon PLIN3 depletion, resulting in extensive tissue necrosis. PLIN3 overexpression in tissue specimens was correlated with increased MIB1 proliferation index, increased autophagy flux, reduced response to radiotherapy and poor prognosis. The impact of LAL depletion on radiotherapy was of lesser importance.

CONCLUSIONS

Assessment of PLIN3 expression may identify subgroups of PCa patients less responsive to radiotherapy, and at high risk of relapse post irradiation. Whether radiotherapy efficacy may be enhanced by concurrent autophagy or PLIN3 inhibition in this sub-group of patients demands clinical evaluation.

A comprehensive gene expression profile analysis of prostate cancer cells resistant to paclitaxel and the potent target to reverse resistance

Background: Paclitaxel resistance is the major clinical obstacle in the chemotherapy of prostate cancer (PCa), but the resistant mechanism is less investigated.Purpose: To establish two paclitaxel-resistant PCa cells, provide a comprehensive gene expression profile analysis of resistant cells and the potential target to reverse resistance.Methods: Two Paclitaxel-resistant PCa cells (PC3/PR, LNcap/PR) were established by gradually increasing drug concentration. MTT and transwell assays were performed to detect drug sensitivity, cell proliferation and migration abilities. RNA-Sequencing (RNA-seq) and bioinformatic analyses were performed to identify abnormally expressed genes (AEGs) in resistant cells, and annotate the biological functions of AEGs. The role of the candidate AEG, TLR-4, on the resistant phenotypes was further investigated.Results: The resistance index of resistant cells was 2-3, and they showed a slower proliferation and increased migration ability. 4741 AEGs were screened out (Log2fold change absolute: log2FC(abs)  > 1) in the resistant cells, and they were enriched in 2'-5'-oligoadenylate synthetase activity and chemical carcinogenesis. A number of AEGs, CCND2, IGFBP3, FOS, SHH, ZEB2, and members of FGF, FGFR and WNT families were also identified to be involved in cancer- and resistant phenotype-related processes. Finally, TLR-4 was validated significantly increased in resistant cells, and knockdown of TLR-4 increased drug-sensitivity, inhibited the proliferation and migration abilities.Conclusions: The study provided a comprehensive gene expression profile of paclitaxel-resistant PCa cells, and TLR-4 could be a potential target to reverse paclitaxel resistance.