PLTP is a p53 target gene with roles in cancer growth suppression and ferroptosis

Ferroptosis: when metabolism meets cell death

We present here a comprehensive update on recent advancements in the field of ferroptosis, with a particular emphasis on its metabolic underpinnings and physiological impacts. After briefly introducing landmark studies that have helped to shape the concept of ferroptosis as a distinct form of cell death, we critically evaluate the key metabolic determinants involved in its regulation. These include the metabolism of essential trace elements such as selenium and iron; amino acids such as cyst(e)ine, methionine, glutamine/glutamate, and tryptophan; and carbohydrates, covering glycolysis, the citric acid cycle, the electron transport chain, and the pentose phosphate pathway. We also delve into the mevalonate pathway and subsequent cholesterol biosynthesis, including intermediate metabolites like dimethylallyl pyrophosphate, squalene, coenzyme Q (CoQ), vitamin K, and 7-dehydrocholesterol, as well as fatty acid and phospholipid metabolism, including the biosynthesis and remodeling of ester and ether phospholipids and lipid peroxidation. Next, we highlight major ferroptosis surveillance systems, specifically the cyst(e)ine/glutathione/glutathione peroxidase 4 axis, the NAD(P)H/ferroptosis suppressor protein 1/CoQ/vitamin K system, and the guanosine triphosphate cyclohydrolase 1/tetrahydrobiopterin/dihydrofolate reductase axis. We also discuss other potential anti- and proferroptotic systems, including glutathione S-transferase P1, peroxiredoxin 6, dihydroorotate dehydrogenase, glycerol-3-phosphate dehydrogenase 2, vitamin K epoxide reductase complex subunit 1 like 1, nitric oxide, and acyl-CoA synthetase long-chain family member 4. Finally, we explore ferroptosis's physiological roles in aging, tumor suppression, and infection control, its pathological implications in tissue ischemia-reperfusion injury and neurodegeneration, and its potential therapeutic applications in cancer treatment. Existing drugs and compounds that may regulate ferroptosis in vivo are enumerated.

Functional Investigations of p53 Acetylation Enabled by Heterobifunctional Molecules

Post-translational modifications (PTMs) dynamically regulate the critical stress response and tumor suppressive functions of p53. Among these, acetylation events mediated by multiple acetyltransferases lead to differential target gene activation and subsequent cell fate. However, our understanding of these events is incomplete due to, in part, the inability to selectively and dynamically control p53 acetylation. We recently developed a heterobifunctional small molecule system, AceTAG, to direct the acetyltransferase p300/CBP for targeted protein acetylation in cells. Here, we expand AceTAG to leverage the acetyltransferase PCAF/GCN5 and apply these tools to investigate the functional consequences of targeted p53 acetylation in human cancer cells. We demonstrate that the recruitment of p300/CBP or PCAF/GCN5 to p53 results in distinct acetylation events and differentiated transcriptional activities. Further, we show that chemically induced acetylation of multiple hotspot p53 mutants results in increased stabilization and enhancement of transcriptional activity. Collectively, these studies demonstrate the utility of AceTAG for functional investigations of protein acetylation.

Ferroptosis in hepatocellular carcinoma: from bench to bedside

The most widespread type of liver cancer, HCC, is associated with disabled cellular death pathways. Despite therapeutic advancements, resistance to current systemic treatments (including sorafenib) compromises the prognosis of patients with HCC, driving the search for agents that might target novel cell death pathways. Ferroptosis, a form of iron-mediated nonapoptotic cell death, has gained considerable attention as a potential target for cancer therapy, especially in HCC. The role of ferroptosis in HCC is complex and diverse. On one hand, ferroptosis can contribute to the progression of HCC through its involvement in both acute and chronic liver conditions. In contrast, having ferroptosis affect HCC cells might be desirable. This review examines the role of ferroptosis in HCC from cellular, animal, and human perspectives while examining its mechanisms, regulation, biomarkers, and clinical implications.

Ferroptosis in health and disease

Ferroptosis is a pervasive non-apoptotic form of cell death highly relevant in various degenerative diseases and malignancies. The hallmark of ferroptosis is uncontrolled and overwhelming peroxidation of polyunsaturated fatty acids contained in membrane phospholipids, which eventually leads to rupture of the plasma membrane. Ferroptosis is unique in that it is essentially a spontaneous, uncatalyzed chemical process based on perturbed iron and redox homeostasis contributing to the cell death process, but that it is nonetheless modulated by many metabolic nodes that impinge on the cells' susceptibility to ferroptosis. Among the various nodes affecting ferroptosis sensitivity, several have emerged as promising candidates for pharmacological intervention, rendering ferroptosis-related proteins attractive targets for the treatment of numerous currently incurable diseases. Herein, the current members of a Germany-wide research consortium focusing on ferroptosis research, as well as key external experts in ferroptosis who have made seminal contributions to this rapidly growing and exciting field of research, have gathered to provide a comprehensive, state-of-the-art review on ferroptosis. Specific topics include: basic mechanisms, in vivo relevance, specialized methodologies, chemical and pharmacological tools, and the potential contribution of ferroptosis to disease etiopathology and progression. We hope that this article will not only provide established scientists and newcomers to the field with an overview of the multiple facets of ferroptosis, but also encourage additional efforts to characterize further molecular pathways modulating ferroptosis, with the ultimate goal to develop novel pharmacotherapies to tackle the various diseases associated with - or caused by - ferroptosis.

Research progress of ferroptosis regulating lipid peroxidation and metabolism in occurrence and development of primary liver cancer

As a highly aggressive tumor, the pathophysiological mechanism of primary liver cancer has attracted much attention. In recent years, factors such as ferroptosis regulation, lipid peroxidation and metabolic abnormalities have emerged in the study of liver cancer, providing a new perspective for understanding the development of liver cancer. Ferroptosis regulation, lipid peroxidation and metabolic abnormalities play important roles in the occurrence and development of liver cancer. The regulation of ferroptosis is involved in apoptosis and necrosis, affecting cell survival and death. Lipid peroxidation promotes oxidative damage and promotes the invasion of liver cancer cells. Metabolic abnormalities, especially the disorders of glucose and lipid metabolism, directly affect the proliferation and growth of liver cancer cells. Studies of ferroptosis regulation and lipid peroxidation may help to discover new therapeutic targets and improve therapeutic outcomes. The understanding of metabolic abnormalities can provide new ideas for the prevention of liver cancer, and reduce the risk of disease by adjusting the metabolic process. This review focuses on the key roles of ferroptosis regulation, lipid peroxidation and metabolic abnormalities in this process.

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

International consensus guidelines for the definition, detection, and interpretation of autophagy-dependent ferroptosis

Macroautophagy/autophagy is a complex degradation process with a dual role in cell death that is influenced by the cell types that are involved and the stressors they are exposed to. Ferroptosis is an iron-dependent oxidative form of cell death characterized by unrestricted lipid peroxidation in the context of heterogeneous and plastic mechanisms. Recent studies have shed light on the involvement of specific types of autophagy (e.g. ferritinophagy, lipophagy, and clockophagy) in initiating or executing ferroptotic cell death through the selective degradation of anti-injury proteins or organelles. Conversely, other forms of selective autophagy (e.g. reticulophagy and lysophagy) enhance the cellular defense against ferroptotic damage. Dysregulated autophagy-dependent ferroptosis has implications for a diverse range of pathological conditions. This review aims to present an updated definition of autophagy-dependent ferroptosis, discuss influential substrates and receptors, outline experimental methods, and propose guidelines for interpreting the results.Abbreviation: 3-MA:3-methyladenine; 4HNE: 4-hydroxynonenal; ACD: accidentalcell death; ADF: autophagy-dependentferroptosis; ARE: antioxidant response element; BH2:dihydrobiopterin; BH4: tetrahydrobiopterin; BMDMs: bonemarrow-derived macrophages; CMA: chaperone-mediated autophagy; CQ:chloroquine; DAMPs: danger/damage-associated molecular patterns; EMT,epithelial-mesenchymal transition; EPR: electronparamagnetic resonance; ER, endoplasmic reticulum; FRET: Försterresonance energy transfer; GFP: green fluorescent protein;GSH: glutathione;IF: immunofluorescence; IHC: immunohistochemistry; IOP, intraocularpressure; IRI: ischemia-reperfusion injury; LAA: linoleamide alkyne;MDA: malondialdehyde; PGSK: Phen Green™ SK;RCD: regulatedcell death; PUFAs: polyunsaturated fatty acids; RFP: red fluorescentprotein;ROS: reactive oxygen species; TBA: thiobarbituricacid; TBARS: thiobarbituric acid reactive substances; TEM:transmission electron microscopy.

Ferroptosis inhibitors: past, present and future

Ferroptosis is a non-apoptotic mode of programmed cell death characterized by iron dependence and lipid peroxidation. Since the ferroptosis was proposed, researchers have revealed the mechanisms of its formation and continue to explore effective inhibitors of ferroptosis in disease. Recent studies have shown a correlation between ferroptosis and the pathological mechanisms of neurodegenerative diseases, as well as diseases involving tissue or organ damage. Acting on ferroptosis-related targets may provide new strategies for the treatment of ferroptosis-mediated diseases. This article specifically describes the metabolic pathways of ferroptosis and summarizes the reported mechanisms of action of natural and synthetic small molecule inhibitors of ferroptosis and their efficacy in disease. The paper also describes ferroptosis treatments such as gene therapy, cell therapy, and nanotechnology, and summarises the challenges encountered in the clinical translation of ferroptosis inhibitors. Finally, the relationship between ferroptosis and other modes of cell death is discussed, hopefully paving the way for future drug design and discovery.

Anchang Yuyang Decoction inhibits experimental colitis-related carcinogenesis by regulating PPAR signaling pathway and affecting metabolic homeostasis of host and microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Inflammatory bowel disease (IBD) presents a risk of carcinogenesis, which escalates with the duration of IBD. Persistent histological inflammation is considered to be the driving factor of colitis carcinogenesis. Effective control of inflammation is helpful to prevent and treat colitis-related colorectal cancer (CAC). Anchang Yuyang Decoction (AYD), a traditional Chinese medicine (TCM) formula, is originated from the ancient prescription of TCM for treating colitis and colorectal cancer. AYD has demonstrated efficacy in treating IBD and potential anti-carcinogenic properties.

AIM OF THE STUDY

This research aims to assess the therapeutic efficacy of AYD in ameliorating experimental colitis-related carcinogenesis induced by AOM/DSS. It further seeks to elucidate its potential mechanisms by integrating multiple omics sequencing approaches.

MATERIALS AND METHODS

A rat model for colitis-related carcinogenesis was developed using azoxymethane (AOM)/dextran sulfate sodium (DSS). UPLC-MS identified AYD's chemical constituents. Rats were administered varying doses of AYD (18.37, 9.19 and 4.59 g/kg) orally for 53 days, with mesalazine as a positive control. The study evaluated anti-carcinogenic effects by examining adenoma number, adenoma load, abnormal crypt foci (ACF), histopathological damage, and tumor-related protein expression. Anti-inflammatory and reparative effects were assessed through body weight, disease activity index (DAI), colon length, spleen index, inflammatory cytokine levels, and tight junction protein expression. The effects on intestinal microbiota and host metabolism were explored through 16S rRNA sequencing, targeted short-chain fatty acid (SCFA) metabonomics, and non-targeted colon metabolomics. Potential AYD targets were identified through transcriptomic sequencing and validated by qRT-PCR and western blotting.

RESULTS

AYD significantly reduced adenoma number, adenoma load, neoplasm-associated lesions, ACF, and tumor-related protein expression (e.g., p53, PCNA) in AOM/DSS-induced rats, thus impeding colitis-related carcinogenesis progression. AYD also alleviated histopathological damage and inflammation, promoting intestinal mucosal barrier repair. Furthermore, AYD modulated intestinal flora structure, enhanced SCFA production, and regulated colon metabolites. Transcriptomic sequencing revealed a significant impact on the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Subsequent qRT-PCR and western blotting experiments indicated AYD's influence in up-regulating PPAR-γ and down-regulating PPAR-α, PPAR-β/δ, and related proteins (thrombomodulin [Thbd], fatty acid binding protein 5 [Fabp5], stearoyl-CoA desaturase 2 [Scd2], phospholipid transfer protein [Pltp]).

CONCLUSIONS

This study demonstrates AYD's ability to inhibit experimental colitis-related carcinogenesis induced by AOM/DSS. Its mechanism likely involves modulation of the PPAR signaling pathway, impacting intestinal microbiota and host metabolic equilibrium.

PHLDA2-mediated phosphatidic acid peroxidation triggers a distinct ferroptotic response during tumor suppression

Although the role of ferroptosis in killing tumor cells is well established, recent studies indicate that ferroptosis inducers also sabotage anti-tumor immunity by killing neutrophils and thus unexpectedly stimulate tumor growth, raising a serious issue about whether ferroptosis effectively suppresses tumor development in vivo. Through genome-wide CRISPR-Cas9 screenings, we discover a pleckstrin homology-like domain family A member 2 (PHLDA2)-mediated ferroptosis pathway that is neither ACSL4-dependent nor requires common ferroptosis inducers. PHLDA2-mediated ferroptosis acts through the peroxidation of phosphatidic acid (PA) upon high levels of reactive oxygen species (ROS). ROS-induced ferroptosis is critical for tumor growth in the absence of common ferroptosis inducers; strikingly, loss of PHLDA2 abrogates ROS-induced ferroptosis and promotes tumor growth but has no obvious effect in normal tissues in both immunodeficient and immunocompetent mouse tumor models. These data demonstrate that PHLDA2-mediated PA peroxidation triggers a distinct ferroptosis response critical for tumor suppression and reveal that PHLDA2-mediated ferroptosis occurs naturally in vivo without any treatment from ferroptosis inducers.

Pioneering the future of cancer therapy: Deciphering the p53-ferroptosis nexus for precision medicine

The TP53 gene, encoding the p53 protein, has been a focal point of research since its 1979 discovery, playing a crucial role in tumor suppression. Ferroptosis, a distinct form of cell death characterized by lipid peroxide accumulation, has gained prominence since its recognition in 2012. Recent studies have unveiled an intriguing connection between p53 and ferroptosis, with implications for cancer therapy. Recent research underscores p53 as a novel target for cancer therapy, influencing key metabolic processes in ferroptosis. Notably, p53 represses the expression of the cystine-glutamate antiporter SLC7A11, supporting p53-mediated tumor growth suppression. Furthermore, under metabolic stress, p53 mitigates ferroptosis sensitivity, aiding cancer cells in coping and delaying cell death. This dynamic interplay between p53 and ferroptosis has far-reaching implications for various diseases, particularly cancer. This review provides a comprehensive overview of ferroptosis in cancer cells, elucidating p53's role in regulating ferroptosis, and explores the potential of targeting p53 to induce ferroptosis for cancer therapy. Understanding this complex relationship between p53 and ferroptosis offers a promising avenue for developing innovative cancer treatments.

Phospholipid transfer protein ameliorates sepsis-induced cardiac dysfunction through NLRP3 inflammasome inhibition

Cardiomyocyte pyroptosis is a primary contributor to sepsis-induced cardiac dysfunction (SICD). Recombinant phospholipid transfer protein (PLTP) have been demonstrated to possess anti-inflammatory and antiseptic properties. However, the effect of PLTP on SICD remains unknown. In this study, we established the in vivo and in vitro sepsis model with the recombinant PLTP treatment. The survival rates of mice, mouse cardiac function, cell viability, the protein level of proinflammatory cytokine, and lactate dehydrogenase level were evaluated. The cardiomyocyte pyroptotic changes were observed. The distribution of PLTP and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) in mouse myocardial tissue and expression of PLTP, apoptosis associated speck like protein containing a CARD (ASC), NLRP3, caspase-1, interleukin (IL)-1β, and Gasdermin D (GSDMD) were detected. PLTP ameliorated the cecal ligation and puncture-induced mouse survival rate decrease and cardiac dysfunction, inhibited the IL-1β, IL-18, and tumor necrosis factor (TNF)-α release, and blocked the NLRP3 inflammasome/GSDMD signaling pathway in septic mice. In vitro, PLTP reversed the lipopolysaccharide-induced cardiomyocyte pyroptosis, expression of IL-1β, IL-6, TNF-α, and activation of the NLRP3 inflammasome/GSDMD signal pathway. Moreover, PLTP could bind to NLRP3 and negatively regulate the activity of the NLRP3 inflammasome/GSDMD signal pathway. This study demonstrated that PLTP can ameliorate SICD by inhibiting inflammatory responses and cardiomyocyte pyroptosis by blocking the activation of the NLRP3 inflammasome/GSDMD signaling pathway.

Expanding Roles of the E2F-RB-p53 Pathway in Tumor Suppression

The transcription factor E2F links the RB pathway to the p53 pathway upon loss of function of pRB, thereby playing a pivotal role in the suppression of tumorigenesis. E2F fulfills a major role in cell proliferation by controlling a variety of growth-associated genes. The activity of E2F is controlled by the tumor suppressor pRB, which binds to E2F and actively suppresses target gene expression, thereby restraining cell proliferation. Signaling pathways originating from growth stimulative and growth suppressive signals converge on pRB (the RB pathway) to regulate E2F activity. In most cancers, the function of pRB is compromised by oncogenic mutations, and E2F activity is enhanced, thereby facilitating cell proliferation to promote tumorigenesis. Upon such events, E2F activates the Arf tumor suppressor gene, leading to activation of the tumor suppressor p53 to protect cells from tumorigenesis. ARF inactivates MDM2, which facilitates degradation of p53 through proteasome by ubiquitination (the p53 pathway). P53 suppresses tumorigenesis by inducing cellular senescence or apoptosis. Hence, in almost all cancers, the p53 pathway is also disabled. Here we will introduce the canonical functions of the RB-E2F-p53 pathway first and then the non-classical functions of each component, which may be relevant to cancer biology.

Serum protein biomarkers for HCC risk prediction in HIV/HBV co-infected people: a clinical proteomic study using mass spectrometry

Background

HBV coinfection is frequent in people living with HIV (PLWH) and is the leading cause of hepatocellular carcinoma (HCC). While risk prediction methods for HCC in patients with HBV monoinfection have been proposed, suitable biomarkers for early diagnosis of HCC in PLWH remain uncommon.

Methods

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to examine serum protein alterations in HCC and non-HCC patients with HIV and HBV co-infection. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Disease Ontology (DO) enrichment analysis were performed on the differentially expressed proteins (DEPs). The risk prediction model was created using five-cross-validation and LASSO regression to filter core DEPs.

Results

A total of 124 DEPs were discovered, with 95 proteins up-regulated and 29 proteins down-regulated. Extracellular matrix organization and membrane component were the DEPs that were most abundant in the categories of biological processes (BP) and cellular components (CC). Proteoglycans in cancer were one of the top three DEPs primarily enriched in the KEGG pathway, and 60.0% of DEPs were linked to various neoplasms in terms of DO enrichment. Eleven proteins, including GAPR1, PLTP, CLASP2, IGHV1-69D, IGLV5-45, A2M, VNN1, KLK11, ANPEP, DPP4 and HYI, were chosen as the core DEPs, and a nomogram was created to predict HCC risk.

Conclusion

In HIV/HBV patients with HCC, several differential proteins can be detected in plasma by mass spectrometry, which can be used as screening markers for early diagnosis and risk prediction of HCC. Monitoring protease expression differences can help in the diagnosis and prognosis of HCC.

Construction and validation of a novel prognostic model of neutrophil‑related genes signature of lung adenocarcinoma

Lung adenocarcinoma (LUAD) remains an incurable disease with a poor prognosis. This study aimed to explore neutrophil‑related genes (NRGs) and develop a prognostic signature for predicting the prognosis of LUAD. NRGs were obtained by intersecting modular genes identified by weighted gene co-expression network analysis (WGCNA) using bulk RNA-seq data and the marker genes of neutrophils identified from single-cell RNA-sequencing(scRNA-seq) data. Univariate Cox regression, least absolute shrinkage and selection operator (LASSO), and multivariate Cox analyses were run to construct a prognostic signature, follow by delineation of risk groups, and external validation. Analyses of ESTIMAT, immune function, Tumor Immune Dysfunction and Exclusion (TIDE) scores, Immune cell Proportion Score (IPS), and immune checkpoint genes between high- and low-risk groups were performed, and then analyses of drug sensitivity to screen for sensitive anticancer drugs in high-risk groups. A total of 45 candidate NRGs were identified, of which PLTP, EREG, CD68, CD69, PLAUR, and CYP27A1 were considered to be significantly associated with prognosis in LUAD and were used to construct a prognostic signature. Correlation analysis showed significant differences in the immune landscape between high- and low-risk groups. In addition, our prognostic signature was important for predicting drug sensitivity in the high-risk group. Our study screened for NRGs in LUAD and constructed a novel and effective signature, revealing the immune landscape and providing more appropriate guidance protocols in LUAD treatment.

An African-Specific Variant of TP53 Reveals PADI4 as a Regulator of p53-Mediated Tumor Suppression

TP53 is the most frequently mutated gene in cancer, yet key target genes for p53-mediated tumor suppression remain unidentified. Here, we characterize a rare, African-specific germline variant of TP53 in the DNA-binding domain Tyr107His (Y107H). Nuclear magnetic resonance and crystal structures reveal that Y107H is structurally similar to wild-type p53. Consistent with this, we find that Y107H can suppress tumor colony formation and is impaired for the transactivation of only a small subset of p53 target genes; this includes the epigenetic modifier PADI4, which deiminates arginine to the nonnatural amino acid citrulline. Surprisingly, we show that Y107H mice develop spontaneous cancers and metastases and that Y107H shows impaired tumor suppression in two other models. We show that PADI4 is itself tumor suppressive and that it requires an intact immune system for tumor suppression. We identify a p53-PADI4 gene signature that is predictive of survival and the efficacy of immune-checkpoint inhibitors.

SIGNIFICANCE

We analyze the African-centric Y107H hypomorphic variant and show that it confers increased cancer risk; we use Y107H in order to identify PADI4 as a key tumor-suppressive p53 target gene that contributes to an immune modulation signature and that is predictive of cancer survival and the success of immunotherapy. See related commentary by Bhatta and Cooks, p. 1518. This article is highlighted in the In This Issue feature, p. 1501.

Identifying p53 Target Genes Using Hypomorphic Variants

SUMMARY

The reduced tumor suppression activity of hypomorphic variants of the TP53 gene was used by Indeglia and colleagues to corroborate PADI4 as a p53 target. The study makes a noteworthy advancement in comprehending the downstream implications of TP53-PDI4, including potential predictions of survival and the efficacy of immunotherapy. See related article by Indeglia et al., p. 1696 (4).

Ferroptosis in gastrointestinal cancer: From mechanisms to implications

Ferroptosis is a form of regulated cell death that is initiated by excessive lipid peroxidation that results in plasma membrane damage and the release of damage-associated molecular patterns. In recent years, ferroptosis has gained significant attention in cancer research due to its unique mechanism compared to other forms of regulated cell death, especially caspase-dependent apoptotic cell death. Gastrointestinal (GI) cancer encompasses malignancies that arise in the digestive tract, including the stomach, intestines, pancreas, colon, liver, rectum, anus, and biliary system. These cancers are a global health concern, with high incidence and mortality rates. Despite advances in medical treatments, drug resistance caused by defects in apoptotic pathways remains a persistent challenge in the management of GI cancer. Hence, exploring the role of ferroptosis in GI cancers may lead to more efficacious treatment strategies. In this review, we provide a comprehensive overview of the core mechanism of ferroptosis and discuss its function, regulation, and implications in the context of GI cancers.

Piperine improves the sensitivity of osteosarcoma cells to doxorubicin by inducing apoptosis and inhibiting the PI3K/AKT/GSK-3β pathway

BACKGROUND

Osteosarcoma is a primary bone malignancy associated with the highest incidence rate. Chemotherapy for osteosarcoma has not substantially changed, and survival of patients with metastatic tumours has reached a plateau. Doxorubicin (DOX) is a broad-spectrum anti-osteosarcoma drug; however, its application is limited due to its high cardiotoxicity. Piperine (PIP) has been verified to drive certain cancer cell death and increases chemosensitivity of DOX. However, the effects of PIP in promoting the chemosensitivity of osteosarcoma to DOX have not been studied.

METHODS

We examined the combined effect of PIP and DOX on U2OS and 143B osteosarcoma cells. CCK-8 assays, scratch assays, flow cytometry analysis, and western blotting were performed. Furthermore, the effect of PIP combined with DOX on osteosarcoma tumours was observed in vivo using nude mice.

RESULTS

PIP can increase the chemosensitivity of U2OS and 143B cells to DOX. Both in vitro and in vivo results showed the dramatic inhibition of cell proliferation and tumour growth by the combined therapy group compared to monotherapy groups. Apoptosis analysis revealed that PIP augments DOX-induced cell apoptosis by upregulating BAX and P53 expression, as well as reducing Bcl-2 expression. Furthermore, PIP also attenuated the initiation of the PI3K/AKT/GSK-3β signaling pathway in osteosarcoma cells by altering the expression levels of P-AKT, P-PI3K and P-GSK3β.

CONCLUSIONS

This study revealed for the first time that PIP can potentiate the sensitivity and cytotoxicity of DOX during osteosarcoma therapy in vitro and in vivo, which probably achieved by inhibiting the PI3K/AKT/GSK-3β signalling pathway.