SGLT2 inhibitor activates the STING/IRF3/IFN-β pathway and induces immune infiltration in osteosarcoma

Sodium-glucose cotransporter 2 inhibitor dapagliflozin prevents ejection fraction reduction, reduces myocardial and renal NF-κB expression and systemic pro-inflammatory biomarkers in models of short-term doxorubicin cardiotoxicity

Background

Anthracycline-mediated adverse cardiovascular events are among the leading causes of morbidity and mortality in patients with cancer. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) exert multiple cardiometabolic benefits in patients with/without type 2 diabetes, chronic kidney disease, and heart failure with reduced and preserved ejection fraction. We hypothesized that the SGLT2i dapagliflozin administered before and during doxorubicin (DOXO) therapy could prevent cardiac dysfunction and reduce pro-inflammatory pathways in preclinical models.

Methods

Cardiomyocytes were exposed to DOXO alone or combined with dapagliflozin (DAPA) at 10 and 100 nM for 24 h; cell viability, iATP, and Ca++ were quantified; lipid peroxidation products (malondialdehyde and 4-hydroxy 2-hexenal), NLRP3, MyD88, and cytokines were also analyzed through selective colorimetric and enzyme-linked immunosorbent assay (ELISA) methods. Female C57Bl/6 mice were treated for 10 days with a saline solution or DOXO (2.17 mg/kg), DAPA (10 mg/kg), or DOXO combined with DAPA. Systemic levels of ferroptosis-related biomarkers, galectin-3, high-sensitivity C-reactive protein (hs-CRP), and pro-inflammatory chemokines (IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL17-α, IL-18, IFN-γ, TNF-α, G-CSF, and GM-CSF) were quantified. After treatments, immunohistochemical staining of myocardial and renal p65/NF-kB was performed.

Results

DAPA exerts cytoprotective, antioxidant, and anti-inflammatory properties in human cardiomyocytes exposed to DOXO by reducing iATP and iCa++ levels, lipid peroxidation, NLRP-3, and MyD88 expression. Pro-inflammatory intracellular cytokines were also reduced. In preclinical models, DAPA prevented the reduction of radial and longitudinal strain and ejection fraction after 10 days of treatment with DOXO. A reduced myocardial expression of NLRP-3 and MyD-88 was seen in the DOXO-DAPA group compared to DOXO mice. Systemic levels of IL-1β, IL-6, TNF-α, G-CSF, and GM-CSF were significantly reduced after treatment with DAPA. Serum levels of galectine-3 and hs-CRP were strongly enhanced in the DOXO group; on the other hand, their expression was reduced in the DAPA-DOXO group. Troponin-T, B-type natriuretic peptide (BNP), and N-Terminal Pro-BNP (NT-pro-BNP) were strongly reduced in the DOXO-DAPA group, revealing cardioprotective properties of SGLT2i. Mice treated with DOXO and DAPA exhibited reduced myocardial and renal NF-kB expression.

Conclusion

The overall picture of the study encourages the use of DAPA in the primary prevention of cardiomyopathies induced by anthracyclines in patients with cancer.

Applications of SGLT2 inhibitors beyond glycaemic control

Sodium-glucose cotransporter 2 (SGLT2) inhibitors were initially developed for their glucose-lowering effects and have shown a modest glycaemic benefit in people with type 2 diabetes mellitus (T2DM). In the past decade, a series of large, robust clinical trials of these therapies have demonstrated striking beneficial effects for various care goals, transforming the chronic disease therapeutic landscape. Cardiovascular safety studies in people with T2DM demonstrated that SGLT2 inhibitors reduce cardiovascular death and hospitalization for heart failure. Subsequent trials in participants with heart failure with reduced or preserved left ventricular ejection fraction demonstrated that SGLT2 inhibitors have beneficial effects on heart failure outcomes. In dedicated kidney outcome studies, SGLT2 inhibitors reduced the incidence of kidney failure among participants with or without diabetes. Post hoc analyses have suggested a range of other benefits of these drugs in conditions as diverse as metabolic dysfunction-associated steatotic liver disease, kidney stone prevention and anaemia. SGLT2 inhibitors have a generally favourable adverse effect profile, although patient selection and medication counselling remain important. Concerted efforts are needed to better integrate these agents into routine care and support long-term medication adherence to close the gap between clinical trial outcomes and those achieved in the real world.

Cancer and Cardiovascular Disease: The Conjoined Twins

Cancer and cardiovascular disease are the two most common causes of death worldwide. As the fields of cardiovascular medicine and oncology continue to expand, the area of overlap is becoming more prominent demanding dedicated attention and individualized patient care. We have come to realize that both fields are inextricably intertwined in several aspects, so much so that the mere presence of one, with its resultant downstream implications, has an impact on the other. Nonetheless, cardiovascular disease and cancer are generally approached independently. The focus that is granted to the predominant pathological entity (either cardiovascular disease or cancer), does not allow for optimal medical care for the other. As a result, ample opportunities for improvement in overall health care are being overlooked. Herein, we hope to shed light on the interconnected relationship between cardiovascular disease and cancer and uncover some of the unintentionally neglected intricacies of common cardiovascular therapeutics from an oncologic standpoint.

The Cardioprotective and Anticancer Effects of SGLT2 Inhibitors: JACC: CardioOncology State-of-the-Art Review

Sodium-glucose cotransporter-2 (SGLT2) inhibitors, originally approved for type 2 diabetes mellitus, have demonstrated efficacy in reducing cardiovascular events, particularly heart failure, in patients with and without diabetes. An intriguing research area involves exploring the potential application of SGLT2 inhibitors in cardio-oncology, aiming to mitigate the cardiovascular adverse events associated with anticancer treatments. These inhibitors present a unique dual nature, offering both cardioprotective effects and anticancer properties, conferring a double benefit for cardio-oncology patients. In this review, the authors first examine the established cardioprotective effects of SGLT2 inhibitors in heart failure and subsequently explore the existing body of evidence, including both preclinical and clinical studies, that supports the use of SGLT2 inhibitors in the context of cardio-oncology. The authors further discuss the mechanisms through which SGLT2 inhibitors protect against cardiovascular toxicity secondary to cancer treatment. Finally, they explore the potential anticancer effects of SGLT2 inhibitors along with their proposed mechanisms.

Unveiling the anticancer effects of SGLT-2i: mechanisms and therapeutic potential

Cancer and diabetes are significant diseases that pose a threat to human health. Their interconnection is complex, particularly when they coexist, often necessitating multiple therapeutic approaches to attain remission. Sodium-glucose cotransporter protein two inhibitors (SGLT-2i) emerged as a treatment for hyperglycemia, but subsequently exhibited noteworthy extra-glycemic properties, such as being registered for the treatment of heart failure and chronic kidney disease, especially with co-existing albuminuria, prompting its assessment as a potential treatment for various non-metabolic diseases. Considering its overall tolerability and established use in diabetes management, SGLT-2i may be a promising candidate for cancer therapy and as a supplementary component to conventional treatments. This narrative review aimed to examine the potential roles and mechanisms of SGLT-2i in the management of diverse types of cancer. Future investigations should focus on elucidating the antitumor efficacy of individual SGLT-2i in different cancer types and exploring the underlying mechanisms. Additionally, clinical trials to evaluate the safety and feasibility of incorporating SGLT-2i into the treatment regimen of specific cancer patients and determining appropriate dosage combinations with established antitumor agents would be of significant interest.

Sodium-glucose cotransporter 2 inhibitors and cancer: a systematic review and meta-analysis

BACKGROUND

The effect of sodium-glucose cotransporter 2 (SGLT2) inhibitors on cancer has yet to be fully elucidated.

OBJECTIVE

This systematic review and meta-analysis investigated the effects of SGLT2 inhibitors on cancer.

METHODS

We searched the PubMed and ClinicalTrials.gov databases up to July 15, 2023, to identify eligible randomized, double-blind, placebo-controlled trials that lasted at least ≥24 weeks. The primary outcome was the overall cancer incidence, and the secondary outcomes were the incidences of various types of cancer. We used the Mantel-Haenszel method, fixed effects model, risk ratio (RR) and 95% confidence interval (CI) to analyze dichotomous variables. Subgroup analysis was performed based on the SGLT2 inhibitor type, baseline conditions, and follow-up duration. All meta-analyses were performed using RevMan5.4.1 and Stata MP 16.0.

RESULTS

A total of 58 publications (59 trials) were included, comprising 113,909 participants with type 2 diabetes mellitus and/or chronic kidney disease and/or high cardiovascular risk and/or heart failure (SGLT2 inhibitor group, 63864; placebo group, 50045). Compared to the placebo SGLT2 inhibitors did not significantly increase the overall incidence of cancer (RR 1.01; 95% CI 0.94-1.08; p = 0.82). However, ertugliflozin did significantly increase the overall incidence of cancer (RR 1.29; 95% CI 1.01-1.64; p = 0.04). SGLT2 inhibitors did not increase the risks of bladder or breast cancer. However, dapagliflozin did significantly reduce the risk of bladder cancer by 47% (RR 0.53; 95% CI 0.35-0.81; p = 0.003). SGLT2 inhibitors had no significant effect on the risks of gastrointestinal, thyroid, skin, respiratory, prostate, uterine/endometrial, hepatic and pancreatic cancers. Dapagliflozin reduced the risk of respiratory cancer by 26% (RR 0.74; 95% CI 0.55-1.00; p = 0.05). SGLT2 inhibitors (particularly mediated by dapagliflozin and ertugliflozin but not statistically significant) were associated with a greater risk of renal cancer than the placebo (RR 1.39; 95% CI 1.04-1.87; p = 0.03).

CONCLUSION

SGLT2 inhibitors did not significantly increase the overall risk of cancer or the risks of bladder and breast cancers. However, the higher risk of renal cancer associated with SGLT2 inhibitors warrants concern.

Risks and Benefits of SGLT-2 Inhibitors for Type 1 Diabetes Patients Using Automated Insulin Delivery Systems-A Literature Review

The primary treatment for autoimmune Diabetes Mellitus (Type 1 Diabetes Mellitus-T1DM) is insulin therapy. Unfortunately, a multitude of clinical cases has demonstrated that the use of insulin as a sole therapeutic intervention fails to address all issues comprehensively. Therefore, non-insulin adjunct treatment has been investigated and shown successful results in clinical trials. Various hypoglycemia-inducing drugs such as Metformin, glucagon-like peptide 1 (GLP-1) receptor agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors, amylin analogs, and Sodium-Glucose Cotransporters 2 (SGLT-2) inhibitors, developed good outcomes in patients with T1DM. Currently, SGLT-2 inhibitors have remarkably improved the treatment of patients with diabetes by preventing cardiovascular events, heart failure hospitalization, and progression of renal disease. However, their pharmacological potential has not been explored enough. Thus, the substantial interest in SGLT-2 inhibitors (SGLT-2is) underlines the present review. It begins with an overview of carrier-mediated cellular glucose uptake, evidencing the insulin-independent transport system contribution to glucose homeostasis and the essential roles of Sodium-Glucose Cotransporters 1 and 2. Then, the pharmacological properties of SGLT-2is are detailed, leading to potential applications in treating T1DM patients with automated insulin delivery (AID) systems. Results from several studies demonstrated improvements in glycemic control, an increase in Time in Range (TIR), a decrease in glycemic variability, reduced daily insulin requirements without increasing hyperglycemic events, and benefits in weight management. However, these advantages are counterbalanced by increased risks, particularly concerning Diabetic Ketoacidosis (DKA). Several clinical trials reported a higher incidence of DKA when patients with T1DM received SGLT-2 inhibitors such as Sotagliflozin and Empagliflozin. On the other hand, patients with T1DM and a body mass index (BMI) of ≥27 kg/m2 treated with Dapagliflozin showed similar reduction in hyperglycemia and body weight and insignificantly increased DKA incidence compared to the overall trial population. Additional multicenter and randomized studies are required to establish safer and more effective long-term strategies based on patient selection, education, and continuous ketone body monitoring for optimal integration of SGLT-2 inhibitors into T1DM therapeutic protocol.

Intestinal Inflammation and Regeneration-Interdigitating Processes Controlled by Dietary Lipids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a disease of chronic inflammatory conditions of the intestinal tract due to disturbance of the inflammation and immune system. Symptoms of IBD include abdominal pain, diarrhea, bleeding, reduced weight, and fatigue. In IBD, the immune system attacks the intestinal tract's inner wall, causing chronic inflammation and tissue damage. In particular, interlukin-6 and interlukin-17 act on immune cells, including T cells and macrophages, to amplify the immune responses so that tissue damage and morphological changes occur. Of note, excessive calorie intake and obesity also affect the immune system due to inflammation caused by lipotoxicity and changes in lipids supply. Similarly, individuals with IBD have alterations in liver function after sustained high-fat diet feeding. In addition, excess dietary fat intake, along with alterations in primary and secondary bile acids in the colon, can affect the onset and progression of IBD because inflammatory cytokines contribute to insulin resistance; the factors include the release of inflammatory cytokines, oxidative stress, and changes in intestinal microflora, which may also contribute to disease progression. However, interfering with de novo fatty acid synthase by deleting the enzyme acetyl-CoA-carboxylase 1 in intestinal epithelial cells (IEC) leads to the deficiency of epithelial crypt structures and tissue regeneration, which seems to be due to Lgr5+ intestinal stem cell function. Thus, conflicting reports exist regarding high-fat diet effects on IBD animal models. This review will focus on the pathological basis of the link between dietary lipids intake and IBD and will cover the currently available pharmacological approaches.

Effects of SGLT2 inhibitors on clinical cancer survival in patients with type 2 diabetes

PURPOSE

According to the preclinical data, sodium-glucose cotransporter 2 (SGLT2) inhibitors (SGLT2is) may exert anticancer effects. Here, we clarified the cancer-specific mortality (primary outcome) and all-cause mortality (secondary outcome) of SGLT2is and their dose-dependency in patients with cancer undergoing standard curative treatments.

METHODS

We analyzed data from patients with type 2 diabetes mellitus (T2DM) diagnosed with cancer between January 1, 2016, and December 31, 2018, enrolled from the Taiwan Cancer Registry database. Kaplan-Meier method was used to estimate all-cause mortality and cancer-specific mortality, comparing survival curves between SGLT2i users and nonusers using the stratified log-rank test. Cox proportional hazards regression was conducted to identify independent predictors for all-cause and cancer-specific mortality among the covariates.

RESULTS

We performed 1:2 propensity score matching of our data, which yielded a final cohort of 50,133 patients with cancer; of them, 16,711 and 33,422 were in the SGLT2i user and nonuser groups, respectively. The adjusted hazard ratio (aHR) for cancer-specific and all-cause mortality in SGLT2i users compared with nonusers was 0.21 (95 % confidence interval [CI]: 0.20-0.22) and 0.22 (95 % CI: 0.21-0.23). We divided the patients into four subgroups stratified by quartiles (Q) of cumulative defined daily doses per year (cDDDs), and all-cause and cancer-specific mortality was noted to significantly decrease with increases in dosage (from Q1 to Q4 cDDDs) in SGLT2i users compared with in nonusers (P < 0.001).

CONCLUSION

SGLT2is increase overall survival and cancer-specific survival in patients with cancer in a dose-dependent manner.

CXXC finger protein 1 (CFP1) bridges the reshaping of genomic H3K4me3 signature to the advancement of lung adenocarcinoma

Histone H3 lysine 4 trimethylation (H3K4me3) is a canonical chromatin modification associated with active gene transcription, playing a pivotal role in regulating various cellular functions. Components of the H3K4me3 methyltransferase complex, known as the proteins associated with SET1 (COMPASS), have been implicated in exerting cancer-protective or cancer-inhibitory effects through inducive H3K4me3 modification. However, the role of the indispensable non-catalytic component of COMPASS CXXC-type zinc finger protein 1 (CFP1) in malignant progression remains unclear. We have unveiled that CFP1 promote lung adenocarcinoma (LUAD) cell proliferation, migration, and invasion while impairing cell apoptosis through in vitro and in vivo models. In addition, high CFP1 expression was identified as emerged as an adverse prognostic indicator across multiple public and in-house LUAD datasets. Notably, CFP1 deficiency led to dual effects on cancer cell transcriptome including extensive inactivation of cancer-promoting as well as activation of cancer repressors. Combining this with the chromatin immunoprecipitation sequencing (ChIP-seq) analysis, we showed that CFP1 ablation reshaped the genomic H3K4me3 distribution signature, with prominent effects on TGF-β and WNT signaling pathways. Collectively, our study proposes that CFP1 mediates tumorigenesis by genomic histone methylation reprogramming, offering insights for future investigations into epigenetic modifications in cancer progression and potential therapeutic advancements.

Strategies involving STING pathway activation for cancer immunotherapy: Mechanism and agonists

Recent studies have expanded the known functions of cGAS-STING in inflammation to a role in cancer due to its participation in activating immune surveillance. In cancer cells, the cGAS-STING pathway can be activated by cytosolic dsDNA derived from genomic, mitochondrial and exogenous origins. The resulting immune-stimulatory factors from this cascade can either attenuate tumor growth or recruit immune cells for tumor clearance. Furthermore, STING-IRF3-induced type I interferon signaling can enforce tumor antigen presentation on dendritic cells and macrophages and thus cross-prime CD8+ T cells for antitumor immunity. Given the functions of the STING pathway in antitumor immunity, multiple strategies are being developed and tested with the rationale of activating STING in tumor cells or tumor-infiltrating immune cells to elicit immunostimulatory effects, either alone or in combination with a range of established chemotherapeutic and immunotherapeutic regimens. Based on the canonical molecular mechanism of STING activation, numerous strategies for inducing mitochondrial and nuclear dsDNA release have been used to activate the cGAS-STING signaling pathway. Other noncanonical strategies that activate cGAS-STING signaling, including the use of direct STING agonists and STING trafficking facilitation, also show promise in type I interferon release and antitumor immunity priming. Here, we review the key roles of the STING pathway in different steps of the cancer-immunity cycle and characterize the canonical and noncanonical mechanisms of cGAS-STING pathway activation to understand the potential of cGAS-STING agonists for cancer immunotherapy.

SGLT2 Inhibitors as Potential Anticancer Agents

Sodium-glucose cotransporter 2 (SGLT2) serves as a critical glucose transporter that has been reported to be overexpressed in cancer models, followed by increased glucose uptake in both mice and humans. Inhibition of its expression can robustly thwart tumor development in vitro and in vivo. SGLT2 inhibitors are a comparatively new class of antidiabetic drugs that have demonstrated anticancer effects in several malignancies, including breast, liver, pancreatic, thyroid, prostate, and lung cancers. This review aims to assess the extent of SGLT involvement in different cancer cell lines and discuss the pharmacology, mechanisms of action, and potential applications of SGLT2 inhibitors to reduce tumorigenesis and its progression. Although these agents display a common mechanism of action, they exhibit distinct affinity towards the SGLT type 2 transporter compared to the SGLT type 1 transporter and varying extents of bioavailability and half-lives. While suppression of glucose uptake has been attributed to their primary mode of antidiabetic action, SGLT2 inhibitors have demonstrated several mechanistic ways to combat cancer, including mitochondrial membrane instability, suppression of β-catenin, and PI3K-Akt pathways, increase in cell cycle arrest and apoptosis, and downregulation of oxidative phosphorylation. Growing evidence and ongoing clinical trials suggest a potential benefit of combination therapy using an SGLT2 inhibitor with the standard chemotherapeutic regimen. Nevertheless, further experimental and clinical evidence is required to characterize the expression and role of SGLTs in different cancer types, the activity of different SGLT subtypes, and their role in tumor development and progression.

Canagliflozin mitigates carfilzomib-induced endothelial apoptosis via an AMPK-dependent pathway

Carfilzomib (CFZ) is a proteasome inhibitor approved for relapsed/refractory multiple myeloma (MM) but its clinical use is limited by cardiovascular toxicity. The mechanisms of CFZ-induced cardiovascular toxicity are not fully understood but endothelial dysfunction may be a common denominator. Here, we first characterized the direct toxic effects of CFZ on endothelial cells (HUVECs and EA.hy926 cells) and tested whether SGLT2 inhibitors, known to have cardioprotective effects, can protect against CFZ-induced toxicity. To determine the chemotherapeutic effect of CFZ in the presence of SGLT2 inhibitors, MM and lymphoma cells were treated with CFZ with or without canagliflozin. CFZ decreased cell viability and induced apoptotic cell death in endothelial cells in a concentration-dependent manner. CFZ also upregulated ICAM-1 and VCAM-1 and downregulated VEGFR-2. These effects were associated with the activation of Akt and MAPK pathways, inhibition of p70s6k, and downregulation of AMPK. Canagliflozin, but not empagliflozin or dapagliflozin, protected endothelial cells from CFZ-induced apoptosis. Mechanistically, canagliflozin abrogated CFZ-induced JNK activation and AMPK inhibition. AICAR (an AMPK activator) protected from CFZ-induced apoptosis, and compound C (an AMPK inhibitor) abrogated the protective effect of canagliflozin, strongly suggesting that AMPK mediates these effects. Canagliflozin did not interfere with the anticancer effect of CFZ in cancer cells. In conclusion, our findings demonstrate for the first time the direct toxic effects of CFZ in endothelial cells and the associated signaling changes. Canagliflozin abrogated the apoptotic effects of CFZ in endothelial cells in an AMPK-dependent mechanism, without interfering with its cytotoxicity in cancer cells.

Hepatic benefits of sodium-glucose cotransporter 2 inhibitors in liver disorders

Diabetic patients are at higher risk of liver dysfunction compared with the normal population. Thus, using hypoglycemic agents to improve liver efficiency is important in these patients. Sodium-glucose cotransporters-2 inhibitors (SGLT2i) are newly developed antidiabetic drugs with potent glucose-lowering effects. However, recent limited evidence suggests that they have extra-glycemic benefits and may be able to exert protective effects on the liver. Hence, these drugs could serve as promising pharmacological agents with multiple benefits against different hepatic disorders. In this review, the current knowledge about the possible effects of SGLT2 inhibitors on different forms of liver complications and possible underlying mechanisms are discussed.

Nanoparticle-Mediated STING Activation for Cancer Immunotherapy

As the first line of host defense against pathogenic infections, innate immunity plays a key role in antitumor immunotherapy. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) (cGAS-STING) pathway has attracted much attention because of the secretion of various proinflammatory cytokines and chemokines. Many STING agonists have been identified and applied into preclinical or clinical trials for cancer immunotherapy. However, the fast excretion, low bioavailability, nonspecificity, and adverse effects of the small molecule STING agonists limit their therapeutic efficacy and in vivo application. Nanodelivery systems with appropriate size, charge, and surface modification are capable of addressing these dilemmas. In this review, the mechanism of the cGAS-STING pathway is discussed and the STING agonists, focusing on nanoparticle-mediated STING therapy and combined therapy for cancers, are summarized. Finally, the future direction and challenges of nano-STING therapy are expounded, emphasizing the pivotal scientific problems and technical bottlenecks and hoping to provide general guidance for its clinical application.

Strategies to Overcome Resistance to Immune-Based Therapies in Osteosarcoma

Improving the prognosis and cure rate of HGOSs (high-grade osteosarcomas) is an absolute need. Immune-based treatment approaches have been increasingly taken into consideration, in particular for metastatic, relapsed and refractory HGOS patients, to ameliorate the clinical results currently achieved. This review is intended to give an overview on the immunotherapeutic treatments targeting, counteracting or exploiting the different immune cell compartments that are present in the HGOS tumor microenvironment. The principle at the basis of these strategies and the possible mechanisms that HGOS cells may use to escape these treatments are presented and discussed. Finally, a list of the currently ongoing immune-based trials in HGOS is provided, together with the results that have been obtained in recently completed clinical studies. The different strategies that are presently under investigation, which are generally aimed at abrogating the immune evasion of HGOS cells, will hopefully help to indicate new treatment protocols, leading to an improvement in the prognosis of patients with this tumor.

Molecular features and predictive models identify the most lethal subtype and a therapeutic target for osteosarcoma

Background

Osteosarcoma is the most common primary malignant bone tumor. The existing treatment regimens remained essentially unchanged over the past 30 years; hence the prognosis has plateaued at a poor level. Precise and personalized therapy is yet to be exploited.

Methods

One discovery cohort (n=98) and two validation cohorts (n=53 & n=48) were collected from public data sources. We performed a non-negative matrix factorization (NMF) method on the discovery cohort to stratify osteosarcoma. Survival analysis and transcriptomic profiling characterized each subtype. Then, a drug target was screened based on subtypes' features and hazard ratios. We also used specific siRNAs and added a cholesterol pathway inhibitor to osteosarcoma cell lines (U2OS and Saos-2) to verify the target. Moreover, PermFIT and ProMS, two support vector machine (SVM) tools, and the least absolute shrinkage and selection operator (LASSO) method, were employed to establish predictive models.

Results

We herein divided osteosarcoma patients into four subtypes (S-I ~ S-IV). Patients of S- I were found probable to live longer. S-II was characterized by the highest immune infiltration. Cancer cells proliferated most in S-III. Notably, S-IV held the most unfavorable outcome and active cholesterol metabolism. SQLE, a rate-limiting enzyme for cholesterol biosynthesis, was identified as a potential drug target for S-IV patients. This finding was further validated in two external independent osteosarcoma cohorts. The function of SQLE to promote proliferation and migration was confirmed by cell phenotypic assays after the specific gene knockdown or addition of terbinafine, an inhibitor of SQLE. We further employed two machine learning tools based on SVM algorithms to develop a subtype diagnostic model and used the LASSO method to establish a 4-gene model for predicting prognosis. These two models were also verified in a validation cohort.

Conclusion

The molecular classification enhanced our understanding of osteosarcoma; the novel predicting models served as robust prognostic biomarkers; the therapeutic target SQLE opened a new way for treatment. Our results served as valuable hints for future biological studies and clinical trials of osteosarcoma.

Modulation of immunosuppressive cells and noncoding RNAs as immunotherapy in osteosarcoma

The most common bone cancer is osteosarcoma (OS), which mostly affects children and teenagers. Early surgical resection combined with chemotherapy significantly improves the prognosis of patients with OS. Existing chemotherapies have poor efficacy in individuals with distant metastases or inoperable resection, and these patients may respond better to novel immunotherapies. Immune escape, which is mediated by immunosuppressive cells in the tumour microenvironment (TME), is a major cause of poor OS prognosis and a primary target of immunotherapy. Myeloid-derived suppressor cells, regulatory T cells, and tumour-associated macrophages are the main immunosuppressor cells, which can regulate tumorigenesis and growth on a variety of levels through the interaction in the TME. The proliferation, migration, invasion, and epithelial-mesenchymal transition of OS cells can all be impacted by the expression of non-coding RNAs (ncRNAs), which can also influence how immunosuppressive cells work and support immune suppression in TME. Interferon, checkpoint inhibitors, cancer vaccines, and engineered chimeric antigen receptor (CAR-T) T cells for OS have all been developed using information from studies on the metabolic properties of immunosuppressive cells in TME and ncRNAs in OS cells. This review summarizes the regulatory effect of ncRNAs on OS cells as well as the metabolic heterogeneity of immunosuppressive cells in the context of OS immunotherapies.

The emerging roles of TRIM21 in coordinating cancer metabolism, immunity and cancer treatment

Tripartite motif containing-21 (TRIM21), an E3 ubiquitin ligase, was initially found to be involved in antiviral responses and autoimmune diseases. Recently studies have reported that TRIM21 plays a dual role in cancer promoting and suppressing in the occurrence and development of various cancers. Despite the fact that TRIM21 has effects on multiple metabolic processes, inflammatory responses and the efficacy of tumor therapy, there has been no systematic review of these topics. Herein, we discuss the emerging role and function of TRIM21 in cancer metabolism, immunity, especially the immune response to inflammation associated with tumorigenesis, and also the cancer treatment, hoping to shine a light on the great potential of targeting TRIM21 as a therapeutic target.