Epidemiological trends, antifungal drug susceptibility and SQLE point mutations in etiologic species of human dermatophytosis in Al-Diwaneyah, Iraq.

Dermatophytes show a wide geographic distribution and are the main causative agents of skin fungal infections in many regions of the world. Recently, their resistance to antifungal drugs has led to an obstacle to effective treatment. To address the lack of dermatophytosis data in Iraq, this study was designed to investigate the distribution and prevalence of dermatophytes in the human population and single point mutations in squalene epoxidase gene (SQLE) of terbinafine resistant isolates. The identification of 102 dermatophytes isolated from clinical human dermatophytosis was performed through morphological and microscopic characteristics followed by molecular analysis based on ITS and TEF-1α sequencing. Phylogeny was achieved through RAxML analysis. CLSI M38-A2 protocol was used to assess antifungal susceptibility of the isolates to four major antifungal drugs. Additionally, the presence of point mutations in SQLE gene, which are responsible for terbinafine resistance was investigated. Tinea corporis was the most prevalent clinical manifestation accounting for 37.24% of examined cases of dermatophytosis. Based on ITS, T. indotineae (50.98%), T. mentagrophytes (19.61%), and M. canis (29.41%) was identified as an etiologic species. T. indotineae and T. mentagrophytes strains were identified as T. interdigitale based on TEF-1α. Terbinafine showed the highest efficacy among the tested antifungal drugs. T. indotineae and T. mentagrophytes showed the highest resistance to antifungal drugs with MICs of 2-4 and 4 µg/mL, while M. canis was the most susceptible species. Three of T. indotineae isolates showed mutations in SQLE gene Phe397Leu substitution. A non-previously described point mutation, Phe311Leu was identified in T. indotineae and mutations Lys276Asn, Phe397Leu and Leu419Phe were diagnosed in T. mentagrophytes XVII. The results of mutation analysis showed that Phe397Leu was a destabilizing mutation; protein stability has decreased with variations in pH, and point mutations affected the interatomic interaction, resulting in bond disruption. These results could help to control the progression of disease effectively and make decisions regarding the selection of appropriate drugs for dermatophyte infections.

Supplementation of Mangiferin to a High-Starch Diet Alleviates Hepatic Injury and Lipid Accumulation Potentially through Modulating Cholesterol Metabolism in Channel Catfish (Ictalurus punctatus).

Starch is a common source of carbohydrates in aqua feed. High-starch diet can cause hepatic injury and lipid accumulation in fish. Mangiferin (MGF) can regulate lipid metabolism and protect the liver, but there is limited research on its effects in fish. In the present study, we investigated whether MGF could ameliorate high-starch-induced hepatic damage and lipid accumulation in channel catfish. The channel catfish (Ictalurus punctatus) were fed one of four experimental diets for eight weeks: a control diet (NCD), a high-starch diet (HCD), an HCD supplemented with 100 mg/kg MGF (100 MGF), and an HCD supplemented with 500 mg/kg MGF (500 MGF). The results demonstrated that the weight gain rate (WGR) (p = 0.031), specific growth rate (SGR) (p = 0.039), and feed conversion efficiency (FCE) (p = 0.040) of the 500 MGF group were significantly higher than those of the NCD group. MGF supplementation alleviated liver damage and improved antioxidant capacity (T-AOC) compared to those of the HCD group (p = 0.000). In addition, dietary MGF significantly reduced plasma glucose (GLU) (p = 0.000), triglyceride (TG) (p= 0.001), and low-density lipoprotein cholesterol (LDL) (p = 0.000) levels. It is noteworthy that MGF significantly reduced the plasma total cholesterol (TC) levels (p = 0.000) and liver TC levels (p = 0.005) of channel catfish. Dietary MGF improves cholesterol homeostasis by decreasing the expression of genes that are involved in cholesterol synthesis and transport (hmgcr, sqle, srebf2, sp1, and ldlr) and increasing the expression of genes that are involved in cholesterol catabolism (cyp7a1). Among them, the largest fold decrease in squalene epoxidase (sqle) expression levels was observed in the 100 MGF or 500 MGF groups compared with the HCD group, with a significant decrease of 3.64-fold or 2.20-fold (p = 0.008). And the 100 MGF or 500 MGF group had significantly decreased (by 1.67-fold or 1.94-fold) Sqle protein levels compared to those of the HCD group (p = 0.000). In primary channel catfish hepatocytes, MGF significantly down-regulated the expression of sqle (p = 0.030) and reduced cholesterol levels (p = 0.000). In NCTC 1469 cells, MGF significantly down-regulated the expression of sqle (p = 0.000) and reduced cholesterol levels (p = 0.024). In conclusion, MGF effectively inhibits sqle expression and reduces cholesterol accumulation. The current study shows how MGF supplementation regulates the metabolism and accumulation of cholesterol in channel catfish, providing a theoretical basis for the use of MGF as a dietary supplement in aquaculture.

Squalene Epoxidase: Its Regulations and Links with Cancers.

Squalene epoxidase (SQLE) is a key enzyme in the mevalonate-cholesterol pathway that plays a critical role in cellular physiological processes. It converts squalene to 2,3-epoxysqualene and catalyzes the first oxygenation step in the pathway. Recently, intensive efforts have been made to extend the current knowledge of SQLE in cancers through functional and mechanistic studies. However, the underlying mechanisms and the role of SQLE in cancers have not been fully elucidated yet. In this review, we retrospected current knowledge of SQLE as a rate-limiting enzyme in the mevalonate-cholesterol pathway, while shedding light on its potential as a diagnostic and prognostic marker, and revealed its therapeutic values in cancers. We showed that SQLE is regulated at different levels and is involved in the crosstalk with iron-dependent cell death. Particularly, we systemically reviewed the research findings on the role of SQLE in different cancers. Finally, we discussed the therapeutic implications of SQLE inhibitors and summarized their potential clinical values. Overall, this review discussed the multifaceted mechanisms that involve SQLE to present a vivid panorama of SQLE in cancers.

Transcriptome Sequencing Unveils a Molecular-Stratification-Predicting Prognosis of Sarcoma Associated with Lipid Metabolism.

Sarcomas are heterogeneous connective tissue malignancies that have been historically categorized into soft tissue and bone cancers. Although multimodal therapies are implemented, many sarcoma subtypes are still difficult to treat. Lipids play vital roles in cellular activities; however, ectopic levels of lipid metabolites have an impact on tumor recurrence, metastasis, and drug resistance. Thus, precision therapies targeting lipid metabolism in sarcoma need to be explored. In this study, we performed a comprehensive analysis of molecular stratification based on lipid metabolism-associated genes (LMAGs) using both public datasets and the data of patients in our cohort and constructed a novel prognostic model consisting of squalene epoxidase (SQLE) and tumor necrosis factor (TNF). We first integrated information on gene expression profile and survival outcomes to divide TCGA sarcoma patients into high- and low-risk subgroups and further revealed the prognosis value of the metabolic signature and immune infiltration of patients in both groups, thus proposing various therapeutic recommendations for sarcoma. We observed that the low-risk sarcoma patients in the TCGA-SARC cohort were characterized by high proportions of immune cells and increased expression of immune checkpoint genes. Subsequently, this lipid metabolic signature was validated in four external independent sarcoma datasets including the CHCAMS cohort. Notably, SQLE, a rate-limiting enzyme in cholesterol biosynthesis, was identified as a potential therapeutic target for sarcoma. Knockdown of SQLE substantially inhibited cell proliferation and colony formation while promoting the apoptosis of sarcoma cells. Terbinafine, an inhibitor of SQLE, displayed similar tumor suppression capacity in vitro. The prognostic predictive model and the potential drug target SQLE might serve as valuable hints for further in-depth biological, diagnostic, and therapeutic exploration of sarcoma.

Squalene monooxygenase facilitates bladder cancer development in part by regulating PCNA.

Bladder cancer (BC) is one of the most common cancers worldwide. Although the treatment and survival rate of BC are being improved, the risk factors and the underlying mechanisms causing BC are incompletely understood. Squalene monooxygenase (SQLE) has been associated with the occurrence and development of multiple cancers but whether it contributes to BC development is unclear. In this study, we performed bioinformatics analysis on paired BC and adjacent non-cancerous tissues and found that SQLE expression is significantly upregulated in BC samples. Knockdown of SQLE impairs viability, induces apoptosis, and inhibits the migration and invasion of BC cells. RNA-seq data reveals that SQLE deficiency leads to dysregulated expression of genes regulating proliferation, migration, and apoptosis. Mass spectrometry-directed interactome screening identifies proliferating cell nuclear antigen (PCNA) as an SQLE-interacting protein and overexpression of PCNA partially rescues the impaired viability, migration, and invasion of BC cells caused by SQLE knockdown. In addition, we performed xenograft assays and confirmed that SQLE deficiency inhibits BC growth in vivo. In conclusion, these data suggest that SQLE promotes BC development and SQLE inhibition may be therapeutically useful in BC treatment.

Knockdown of SQLE promotes CD8+ T cell infiltration in the tumor microenvironment.

Cholesterol biosynthesis and metabolism are critical aspects that shape the process of tumor development and associated microenvironmental conditions owing to the ability of cholesterol to drive tumor growth and invasion. Squalene Epoxidase (SQLE) is the second rate-limiting enzyme involved in the synthesis of cholesterol. The functional role of SQLE within the tumor microenvironment, however, has yet to be established. Here we show that SQLE is distinctively expressed across most types of cancer, and the expression level is highly correlated with tumor mutation burden and microsatellite instability. Accordingly, SQLE was identified as a prognostic risk factor in cancer patients. In addition, we observed a negative correlation between SQLE expression and immune cell infiltration across multiple cancers, and murine xenograft model further confirmed that SQLE knockdown was associated with enhanced intratumoral CD8+ T cell infiltration. Using next-generation sequencing, we identified 410 genes distinctively expressed in tumors exhibiting SQLE inhibition. KEGG and GO analysis further verified that SQLE altered the immune response in the tumor microenvironment. Furthermore, we found that the metabolism and translation of proteins is the main binding factor with SQLE. Our findings ascertain that SQLE is a potential target in multiple cancers and suppressing SQLE establishes an essential mechanism for shaping tumor microenvironment.

The Potential of Lipid Droplet-associated Genes as Diagnostic and Prognostic Biomarkers in Head and Neck Squamous Cell Carcinoma.

OBJECTIVE: The role of lipid droplets (LDs) and lipid droplet-associated genes (LD-AGs) remains unclear in head and neck squamous cell carcinoma (HNSCC). This study aimed to investigate LDs in HNSCC and identify LD-AGs essential for the diagnosis and prognosis of HNSCC patients. METHODS: The LDs in the HNSCC and normal cell lines were stained with oil red O. Bioinformatic analysis was used to find LD-AGs in HNSCC that had diagnostic and prognostic significance. RESULTS: LDs accumulation was increased in HNSCC cell lines compared with normal cell lines (P<0.05). Fifty-three differentially expressed genes, including 34 upregulated and 19 downregulated, were found in HNSCC based on the TCGA platform (P<0.05). Then, 53 genes were proved to be functionally enriched in lipid metabolism and LDs. Among them, with an AUC value > 0.7, 34 genes demonstrated a high predictive power. Six genes (AUP1, CAV1, CAV2, CAVIN1, HILPDA, and SQLE) out of 34 diagnostic genes were linked to overall survival in patients with HNSCC (P<0.05). The significant prognostic factors AUP1, CAV1, CAV2, and SQLE were further identified using the univariate and multivariate cox proportional hazard models (P<0.05). The protein expression of CAV2 and SQLE was significantly increased in the HNSCC tissue compared to normal tissues (P<0.05). Finally, the knockdown of the four LD-AGs decreased LDs accumulation, respectively. CONCLUSIONS: Increased LDs accumulation was a hallmark of HNSCC, and AUP1, CAV1, CAV2, and SQLE were discovered as differentially expressed LD-AGs with diagnostic and prognostic potential in HNSCC.

Pachymaran regulates pyroptosis of liver cancer cells via SQLE/NLRP3/GSDMD signaling pathway / 中国病理生理杂志

AIM:Using bioinformatics analysis and experiment validation to explore the differential expres-sion genes related to abnormal lipid metabolism in hepatocellular carcinoma(HCC)and the molecular mechanism of pachymaran affecting pyroptosis through squalene epoxidase(SQLE)/nucleotide-binding oligomerization domain-like re-ceptor protein 3(NLRP3)/gasdermin D(GSDMD)signaling pathway.METHODS:(1)The GEO,GSEA,DAVID,STRING and GEPIA databases were employed to screen abnormal lipid metabolism-related differentially expressed genes in HCC.(2)The tumor tissues from HCC patients(n=9)were collected to verify the differential expression of SQLE.(3)The inhibitory effect of pachymaran on the viability of human HCC cell line HepG2 was measured by CCK-8 assay.(4)The HepG2 cells were divided into control group and pachymaran(800 mg/L)group.The cell migration was analyzed by wound-healing assay,and RT-qPCR was used to measure SQLE mRNA expression.(5)The HepG2 cells with overexpres-sion of SQLE(OE-SQLE)were divided into 5 groups as follows:control group,overexpression negative control(OE-NC)group,OE-SQLE group,OE-NC+pachymaran group,and OE-SQLE+pachymaran group.The mRNA and protein expres-sion levels of SQLE and pyroptosis-related factors were determined by RT-qPCR and Western blot.Colorimetric method and ELISA were used to measure lactate dehydrogenase(LDH),interleukin-1β(IL-1β)and IL-18 levels.The necrosis of HepG2 cells was analyzed by flow cytometry.RESULTS:The SQLE gene was screened through bioinformatics analysis,and its mRNA expression was significantly increased in tumor tissues from HCC patients(P＜0.01).In cell experiments,treatment with 800 mg/L pachymaran for 48 h had a significant inhibitory effect on HepG2 cell viability,and the expres-sion of SQLE mRNA was reduced(P＜0.01).After overexpression of SQLE,the mRNA and protein levels of pyroptosis-re-lated factors,necrotic rate,and LDH,IL-1β and IL-18 levels were significantly decreased(P＜0.05).After treatment with pachymaran,the above indicators were significantly increased(P＜0.05).CONCLUSION:The SQLE is abnormal-ly highly expressed in HCC,and pachymaran can affect the growth of HCC cells by activating the NLRP3/GSDMD pyropto-sis pathway through SQLE.

The expression of squalene epoxidase in human gastric cancer and its clinical significance.

Context: Squalene epoxidase (SQLE) is overexpressed in a variety of tumors, which may play an important role in their tumorigenesis, development, and prognosis. Aims: The aim of this study is to investigate the expression of SQLE and explore its clinicopathological significance in gastric cancer. Settings and Design: The correlation between its positive expression and the pathological characteristics of patients (such as sex, age, tumor size, survival, tumor differentiation, TNM staging, and lymph node metastasis) was analyzed. Materials and Methods: Immunohistochemical method was used to detect its expression in 107 cases of gastric carcinoma and 34 cases of tumor-adjacent tissues. Statistical Analysis Used: Counting data were analyzed by Chi-square test. Its overall survival was analyzed by Kaplan-Meier method and log-rank test. Its hazard factors were analyzed by Cox multivariate analysis. Results: The positive rate of SQLE in gastric cancer is 67.3%, which is higher than that in tumor-adjacent tissues (17.6%), <0.001. Expression of SQLE is closely related to tumor differentiation, TNM staging and lymph node metastasis (P = 0.030, P = 0.009, and P = 0.011, respectively). Furthermore, compared with those low expression of SQLE, the patients of overexpression had worse overall survival by Kaplan-Meier analysis (P = 0.025). Cox multivariate analysis shows that lymph node metastasis, tumor differentiation, SQLE, and TNM staging are independent factors for prognosis of gastric cancer (P = 0.003, 0.020, 0.018, and P = 0.001 respectively). Conclusions: SQLE is overexpressed in gastric cancer. It could be used for the diagnosis and prognosis of the gastric cancer patients.

Squalene epoxidase promotes breast cancer progression by regulating CCNB1 protein stability.

BACKGROUND: Breast cancer (BC) is a prevalent malignancy affecting women, characterized by a substantial occurrence rate. Squalene epoxidase (SQLE) is a crucial regulator of ferroptosis and has been associated with promoting cell growth and invasion in different types of human cancers. This study aimed to investigate the functional significance of SQLE in BC and elucidate the underlying molecular mechanisms involved. METHODS: SQLE expression levels in BC tissues were evaluated using quantitative real-time polymerase chain reaction, western blotting, and immunohistochemistry. Cell viability, invasion, migration, and cell cycle distribution were assessed using a combination of assays, including the Cell Counting Kit-8, EdU, colony formation, Transwell, and wound healing assays and flow cytometry analysis. Measurement of intracellular reactive oxygen species (ROS), malondialdehyde assay, and glutathione assay were utilized to investigate ferroptosis. Furthermore, co-immunoprecipitation and immunofluorescence assays were conducted to explore the correlation between SQLE and CCNB1. The in vivo tumor growth was evaluated by conducting a xenograft tumorigenicity assay to investigate the impact of SQLE. RESULTS: SQLE expression was significantly increased in BC, and higher SQLE expression levels were significantly associated with an unfavorable prognosis. In vitro functional assays revealed that the overexpression of SQLE markedly enhanced the proliferation, migration, and invasion capacities of BC cells. Furthermore, SQLE overexpression facilitated tumor growth in nude mice. Mechanistically, SQLE alleviated the ubiquitination modification of CCNB1, leading to enhanced stability of the CCNB1 protein and decreased intracellular ROS levels. Ultimately, this inhibited ferroptosis and facilitated the progression of BC. Our findings have provided insights into a crucial pathway by which elevated SQLE expression confers protection to BC cells against ferroptosis, thus promoting cancer progression. SQLE may serve as a novel oncological marker and a potential therapeutic target for BC progression. CONCLUSIONS: In conclusion, this study provides evidence that SQLE plays a regulatory role in BC progression by modulating CCNB1 and ferroptosis. These findings offer valuable insights into the role of SQLE in the pathogenesis of BC and demonstrate its potential as a therapeutic target for treating BC.

p53 and MYC-regulated squalene epoxidase as Achilles heel in colorectal cancer.

The transcription factors p53 and MYC are often considered non-druggable targets, but their dysregulation can generate new dependencies and treatment opportunities in cancer cells. The p53 and MYC-regulated squalene epoxidase (SQLE) has been identified as a potential Achilles heel in colorectal cancer. This is of great interest because the FDA-approved anti-fungal SQLE inhibitor Terbinafine could be repurposed to treat colorectal cancer patients.

Squalene epoxidase/SQLE is a candidate target for treatment of colorectal cancers with p53 mutation and elevated c-MYC expression.

Elevated expression of c-MYC and inactivation of p53 represent two of the most common alterations in colorectal cancer (CRC). However, c-MYC and defective p53 are difficult to target therapeutically. Therefore, effectors downstream of both c-MYC and p53 may represent attractive, alternative targets for cancer treatment. In a bioinformatics screen we identified Squalene epoxidase/SQLE as a candidate therapeutic target that appeared to be especially relevant for cell survival in CRCs, which display elevated c-MYC expression and loss of p53 function. SQLE is a rate-limiting enzyme in the cholesterol synthesis. Here, we show that p53 supresses SQLE expression, cholesterol levels, and cell viability via the induction of miR-205, which directly targets SQLE. Furthermore, c-MYC induced SQLE expression directly and via its target gene AP4. The transcription factor AP4/TFAP4 directly induced SQLE expression and cholesterol levels, whereas inactivation of AP4 resulted in decreased SQLE expression and caused resistance to Terbinafine, an inhibitor of SQLE. Inhibition of SQLE decreased viability of CRC cells. This effect was enhanced in CRCs cells with p53 inactivation and/or enhanced c-MYC/AP4 expression. Altogether, our results demonstrate that SQLE represents a vulnerability for CRCs with p53 inactivation and elevated c-MYC activity.

A Terbinafine Sensitive Trichophyton indotineae Strain in Italy: The First Clinical Case of tinea corporis and onychomycosis.

Trichophyton indotineae is an emerging dermatophyte species that plays a relevant role in human healthcare. It has been associated with severe chronic skin infections and a high level of terbinafine resistance. T. indotineae is endemic to India, Iran, and Iraq but several cases have been reported in Europe, recently. In this manuscript, the authors report the first clinical description of a tinea corporis and onychomycosis due to T. indotineae. The patient was a 42-year-old female from India that has lived in Umbria (Central Italy) for the last two years. Firstly, a dermatological examination suggested dermatophytosis: mycology isolation from cultures and macro- and microscopical features identified the colonies as belonging to the T. mentagrophytes/T. interdigitale species complex. Subsequently, ITS1/ITS4 end-point PCR and Sanger sequencing identified the strain as T. indotineae. Lastly, a DermaGenius® Resistance Multiplex real-time PCR assay was carried out, targeting the mutations in the SQLE gene to establish terbinafine resistance or susceptibility of the strain. The melting curve observed was compatible with wild-type positive control, identifying the strain as T. indotineae terbinafine-sensitive. An oral terbinafine treatment was associated with a topical ciclopirox nail solution, resulting in remission in its clinical manifestation. On 3 July 2023, the local Prevention Service notified the case to the Ministry of Health that then reported the information at national and international levels.

SQLE Knockdown inhibits bladder cancer progression by regulating the PTEN/AKT/GSK3ß signaling pathway through P53.

Bladder cancer (BCa) is one of the most common malignancies worldwide. However, the lack of accurate and effective targeted drugs has become a major problem in current clinical treatment of BCa. Studies have demonstrated that squalene epoxidase (SQLE), as a key rate-limiting enzyme in cholesterol biosynthesis, is involved in cancer development. In this study, our analysis of The Cancer Genome Atlas, The Genotype-Tissue Expression, and Gene Expression Omnibus databases showed that SQLE expression was significantly higher in cancer tissues than it was in adjacent normal tissues, and BCa tissues with a high SQLE expression displayed a poor prognosis. We then confirmed this result in qRT-PCR and immunohistochemical staining experiments, and our vitro studies demonstrated that SQLE knockdown inhibited tumor cell proliferation and metastasis through the PTEN/AKT/GSK3ß signaling pathway. By means of rescue experiments, we proved that that P53 is a key molecule in SQLE-mediated regulation of the PTEN/AKT/GSK3ß signaling pathway. Simultaneously, we verified the above findings through a tumorigenesis experiment in nude mice. In conclusion, our study shows that SQLE promotes BCa growth through the P53/PTEN/AKT/GSK3ß axis, which may serve as a therapeutic biological target for BCa.

Hsa_circ_0028007 regulates the progression of nasopharyngeal carcinoma through the miR-1179/SQLE axis.

Nasopharyngeal carcinoma (NPC) is one of the most ordinary malignant tumors. Current research has suggested that circular RNAs play an important role in tumor genesis and progression. The purpose of this study is to explore the function and underlying mechanisms of circ_0028007 in NPC. The levels of circ_0028007, miR-1179, and Squalene epoxidase (SQLE) were detected by quantitative real-time polymerase chain reaction. Cell proliferation was detected by colony formation assay and thymidine analog 5-ethynyl-2'-deoxyuridine assay. Cell apoptosis was detected by flow cytometry. Relevant kits detected caspase-3, glucose, and lactate levels. Western blot assay was used to detect the related protein content. Dual-luciferase reporter assay and RNA pull-down assay were used to examine the target relationship between miR-1179 and circ_0028007 or SQLE. circ_0028007 and SQLE were highly expressed in NPC, while miR-1179 was lowly expressed. circ_0028007 silencing inhibited NPC cell proliferation and promoted apoptosis. However, the effect of circ_0028007 down-regulation on NPC cells was partially restored by co-transfection with miR-1179 inhibitor. Overexpression of SQLE partially restored the cell proliferation inhibited by circ_0028007 knockdown. circ_0028007 could regulate NPC progression via the miR-1179/SQLE axis. Therefore, circ_0028007 might be a new therapeutic target for NPC.

Inhibition of squalene epoxidase linking with PI3K/AKT signaling pathway suppresses endometrial cancer.

Endometrial cancer (EC) is a common malignant tumor that lacks any therapeutic target and, in many cases, recurrence is the leading ca use of morbidity and mortality in women. Widely known EC has a strongly positive correlation with abnormal lipid metabolism. Squalene epoxidase (SQLE), a crucial enzyme in the cholesterol synthesis pathway regulating lipid metabolic processes has been found to be associated with various cancers in recent years. Here, we focused on studying the role of SQLE in EC. Our study revealed that SQLE expression level was upregulated significantly in EC tissues. In vitro experiments showed that SQLE overexpression significantly promoted the proliferation, and inhibited cell apoptosis of EC cells, whereas SQLE knockdown or use of terbinafine showed the opposite results. Furthermore, we found out that the promotional effect of SQLE on the proliferation of EC cells might be achieved by activating the PI3K/AKT pathway. In vivo, studies confirmed that the knockdown of SQLE or terbinafine can observably inhibit tumor growth in nude mice. These results indicate that SQLE may promote the progression of EC by activating the PI3K/AKT pathway. Moreover, SQLE is a potential target for EC treatment and its inhibitor, terbinafine, has the potential to become a targeted drug for EC treatment.

The potential role and mechanism of circRNA/miRNA axis in cholesterol synthesis.

Cholesterol levels are an initiating risk factor for atherosclerosis. Many genes play a central role in cholesterol synthesis, including HMGCR, SQLE, HMGCS1, FDFT1, LSS, MVK, PMK, MVD, FDPS, CYP51, TM7SF2, LBR, MSMO1, NSDHL, HSD17B7, DHCR24, EBP, SC5D, DHCR7, IDI1/2. Especially, HMGCR, SQLE, FDFT1, LSS, FDPS, CYP51, and EBP are promising therapeutic targets for drug development due to many drugs have been approved and entered into clinical research by targeting these genes. However, new targets and drugs still need to be discovered. Interestingly, many small nucleic acid drugs and vaccines were approved for the market, including Inclisiran, Patisiran, Inotersen, Givosiran, Lumasiran, Nusinersen, Volanesorsen, Eteplirsen, Golodirsen, Viltolarsen, Casimersen, Elasomeran, Tozinameran. However, these agents are all linear RNA agents. Circular RNAs (circRNAs) may have longer half-lives, higher stability, lower immunogenicity, lower production costs, and higher delivery efficiency than these agents due to their covalently closed structures. CircRNA agents are developed by several companies, including Orna Therapeutics, Laronde, and CirCode, Therorna. Many studies have shown that circRNAs regulate cholesterol synthesis by regulating HMGCR, SQLE, HMGCS1, ACS, YWHAG, PTEN, DHCR24, SREBP-2, and PMK expression. MiRNAs are essential for circRNA-mediated cholesterol biosynthesis. Notable, the phase II trial for inhibiting miR-122 with nucleic acid drugs has been completed. Suppressing HMGCR, SQLE, and miR-122 with circRNA_ABCA1, circ-PRKCH, circEZH2, circRNA-SCAP, and circFOXO3 are the promising therapeutic target for drug development, specifically the circFOXO3. This review focuses on the role and mechanism of the circRNA/miRNA axis in cholesterol synthesis in the hope of providing knowledge to identify new targets.

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.

The interaction between polyphyllin I and SQLE protein induces hepatotoxicity through SREBP-2/HMGCR/SQLE/LSS pathway.

Polyphyllin I (PPI) and polyphyllin II (PII) are the main active substances in the Paris polyphylla. However, liver toxicity of these compounds has impeded their clinical application and the potential hepatotoxicity mechanisms remain to be elucidated. In this work, we found that PPI and PII exposure could induce significant hepatotoxicity in human liver cell line L-02 and zebrafish in a dose-dependent manner. The results of the proteomic analysis in L-02 cells and transcriptome in zebrafish indicated that the hepatotoxicity of PPI and PII was associated with the cholesterol biosynthetic pathway disorders, which were alleviated by the cholesterol biosynthesis inhibitor lovastatin. Additionally, 3-hydroxy-3-methy-lglutaryl CoA reductase (HMGCR) and squalene epoxidase (SQLE), the two rate-limiting enzymes in the cholesterol synthesis, selected as the potential targets, were confirmed by the molecular docking, the overexpression, and knockdown of HMGCR or SQLE with siRNA. Finally, the pull-down and surface plasmon resonance technology revealed that PPI could directly bind with SQLE but not with HMGCR. Collectively, these data demonstrated that PPI-induced hepatotoxicity resulted from the direct binding with SQLE protein and impaired the sterol-regulatory element binding protein 2/HMGCR/SQLE/lanosterol synthase pathways, thus disturbing the cholesterol biosynthesis pathway. The findings of this research can contribute to a better understanding of the key role of SQLE as a potential target in drug-induced hepatotoxicity and provide a therapeutic strategy for the prevention of drug toxic effects with similar structures in the future.