SQLE Knockdown inhibits bladder cancer progression by regulating the PTEN/AKT/GSK3β signaling pathway through P53

Exosomal 4EBP1 promotes head and neck cancer progression via regulating mitochondrial fission

Head and neck cancer (HNC) is the sixth most common cancer around the globe with raised incidence and mortality. Despite the advancement in diagnostic and therapeutic approaches the burden of HNC has not reduced. Therefore, investigation on key molecular mechanisms that contributes to the progression of HNC is required to identify promising therapeutic targets. Exosomes are nanosized vesicles and recently emerged as a carrier of tumorigenic proteins essential for cancer progression. However, the role of exosomal proteins in HNC progression remains largely unclear. Eukaryotic Initiation Factor 4E-Binding protein 1 (4EBP1) regulates the protein synthesis and plays a crucial role in the progression of different forms of cancer. Our current study revealed that 4EBP1 is carried in human serum exosomes and upregulated in HNC serum exosomes than healthy controls (HC) and we observed that coculturing the 4EBP1 upregulated HNC serum exosomes (HNC Exo) promoted the growth and migration of HEp-2 cells. Further, we examined the underlying mechanism by knockdown of 4EBP1 in HEp-2 cells (4EBP1 KD). Our results showed that knockdown of 4EBP1 have suppressed the migration and progression of cancer cells. Mechanistically, knockdown of 4EBP1 downregulated mitochondrial fission modulators DRP1 and FIS1 and attenuated the migration of HNC cancer cells by suppressing TGFβ and upregulating PTEN. Together our findings suggest that 4EBP1 is upregulated in circulating exosomes and promotes HNC progression via modulating mitochondrial fission and could be a potential therapeutic target for HNC.

Review of recent molecular pathology of bladder urothelial carcinoma

Bladder urothelial carcinoma (BUC) is a common malignant tumour with a high recurrence rate and mortality. Research on the molecular pathological basis of BUC is extensive. However, the specific pathogenesis and effective treatment of BUC remain to be further studied. Studies on mutation spectrum, DNA methylation, non-coding RNA, proliferation and apoptosis signalling pathways, cell cycle control, transcription factors, DNA damage repair, immune checkpoint and tumour microenvironment have provided therapeutic strategies for the diagnosis, treatment and prognosis evaluation of BUC. This study provided new insights into the molecular pathology of BUC, helped to improve the diagnosis, treatment and prognostic evaluation of patients and drove the use of precision medicine in the treatment of BUC.

SQLE amplification accelerates esophageal squamous cell carcinoma tumorigenesis and metastasis through oncometabolite 2,3-oxidosqualene repressing Hippo pathway

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent cancers worldwide, characterized by a dismal prognosis and elusive therapeutic targets. Dysregulated cholesterol metabolism is a critical hallmark of cancer cells, facilitating tumor progression. Here, we used whole genome sequencing data from several ESCC cohorts to identify the important role of squalene epoxidase (SQLE) in promoting ESCC tumorigenesis and metastasis. Specifically, our findings highlight the significance of 2,3-oxidosqualene, an intermediate metabolite of cholesterol biosynthesis, synthesized by SQLE and metabolized by lanosterol synthase (LSS), as a key regulator of ESCC progression. Mechanistically, the interaction between 2,3-oxidosqualene and vinculin enhances the nuclear accumulation of Yes-associated protein 1 (YAP), thereby increasing YAP/TEAD-dependent gene expression and accelerating both tumor growth and metastasis. In a 4-nitroquinoline 1-oxide (4-NQO)-induced ESCC mouse model, overexpression of Sqle resulted in accelerated tumorigenesis compared to wild-type controls, highlighting the pivotal role of SQLE in vivo. Furthermore, elevated SQLE expression in ESCC patients correlates with a poorer prognoses, suggesting potential therapeutic avenues for treatment. In conclusion, our study elucidates the oncogenic function of 2,3-oxidosqualene as a naturally occurring metabolite and proposes modulation of its levels as a promising therapeutic strategy for ESCC.

Advances in understanding the role of squalene epoxidase in cancer prognosis and resistance

Recently, there has been burgeoning interest in the involvement of cholesterol metabolism in cancer. Squalene epoxidase (SQLE), as a critical rate-limiting enzyme in the cholesterol synthesis pathway, has garnered attention due to its overexpression in various cancer types, thereby significantly impacting tumor prognosis and resistance mechanisms. Firstly, SQLE contributes to unfavorable prognosis through diverse mechanisms, encompassing modulation of the PI3K/AKT signaling pathway, manipulation of the cancer microenvironment, and participation in ferroptosis. Secondly, directing efforts towards targeting SQLE, via mechanisms such as the PI3K/AKT pathway, presents promising avenues for overcoming resistance to conventional therapies such as endocrine cancer therapy, chemotherapy, immunotherapy, or radiotherapy. Moreover, the effectiveness of SQLE protein inhibitors in impeding cancer progression may either depend directly on SQLE inhibition or function through alternative pathways separate from SQLE. This mini-review offers insights into the intricate mechanisms through which SQLE affects the prognosis and resistance profiles across diverse cancer types, while succinctly elucidating the mechanisms underpinning the anticancer effects of SQLE protein inhibitors. Furthermore, this mini-review underscores the necessity for further investigations into the interplay between SQLE and cancer, proposing potential avenues for future research, with the aim of serving as a reference for exploring the mechanisms governing the role of SQLE in cancer regulation.

SQLE promotes osteosarcoma progression via activating TGFβ/SMAD signaling pathway

BACKGROUND

The prognosis of advanced osteosarcoma (OS) has remained stagnant in last decades, requiring the identification of novel therapeutic targets. Recently, much attention was paid to the role of squalene epoxidase (SQLE), a rate-limiting enzyme in cholesterol metabolism, in the field of oncology, while the specific role of SQLE in OS has not been sufficiently elucidated. The present study aims to investigate the role of SQLE in the progression of OS and explore the potential mechanisms.

METHODS

The expression levels of SQLE in OS tissues and adjacent normal tissues were compared using bioinformatic methods and experiments. Kaplan-Meier survival analysis and univariate and multivariate Cox analysis were performed to detect the association of SQLE expression and patient' prognosis. Stably cell lines with SQLE knockdown or overexpression were constructed by lentivirus infection. CCK-8, colony formation, scratch healing, and Transwell invasion assays were carried out to explore the effect of SQLE knockdown or overexpression on the proliferation, migration, and invasion of OS cells. Gene set enrichment analysis was conducted to reveal signaling pathways associated with SQLE expression. The effect of SQLE on TGFβ/SMAD signaling pathway were explored by Western blot assay.

RESULTS

Here, we found a notable rise of SQLE expression in OS tissues and cell lines. Survival analysis showed that individuals with high SQLE expression had a lower median overall survival time compared to those with low SQLE expression. Univariate and multivariate Cox regression analyses showed that SQLE might have the potency to serve as an independently prognostic biomarker in OS. Loss- and gain-of-function experiments indicated that silence of SQLE suppressed OS cell proliferation, migration, and invasion, while overexpression of SQLE exerted the opposite effects. Mechanistically, TGF-β signaling pathway was identified as the downstream pathway of SQLE through bioinformatic methods, and the results of Western blot assay showed that SQLE positively regulated the activity of TGFβ1/SMAD2/3 signaling in OS. Resue experiments demonstrated that SB431542, a small molecule that inhibits TGFβ/SMAD signaling, could partly reverse the promoting effects of SQLE on OS cell proliferation, migration, and invasion.

CONCLUSION

Our results provided preliminary evidences that SQLE was a tumor-promoting factor and prognosis predictor in OS. SQLE promoted OS cell proliferation, migration, and invasion via activating TGFβ/SMAD signaling and targeting SQLE might be a potential strategy for the treatment of OS.

Inhibition of KDM4A restricts SQLE transcription and induces oxidative stress imbalance to suppress bladder cancer

In clinical practice, the limited efficacy of standard comprehensive therapy for advanced bladder cancer and the lack of targeted treatment options are well recognized. Targeting abnormal epigenetic modifications in tumors has shown considerable potential in cancer therapy. Through drug screening in tumor organoids, we identified that ML324, a histone lysine demethylase 4A (KDM4A) inhibitor, exhibits potent antitumor effects in both in vitro and in vivo cancer models. Mechanistically, Kdm4a demethylates H3K9me3, leading to chromatin opening and increased accessibility of Gabpa to the squalene epoxidase (Sqle) gene promoter, resulting in transcriptional activation. Inhibition of Kdm4a downregulates Sqle transcription, blocking cholesterol synthesis and causing squalene (SQA) accumulation. This process induces reactive oxygen species (ROS) clearance and suppresses JNK/c-Jun phosphorylation, ultimately inducing apoptosis. Furthermore, ML324 treatment significantly inhibited tumor growth in bladder cancer patient-derived xenograft (PDX) models. Our findings reveal the presence of a Kdm4a-Sqle-ROS-JNK/c-Jun signaling axis that regulates oxidative stress balance, offering a novel strategy for targeted therapy in bladder cancer.

Squalene monooxygenase (SQLE) protects ovarian cancer cells from ferroptosis

Altered cholesterol metabolism has been linked to a poor prognosis in various types of cancer. Cholesterol oxidation can lead to lipid peroxidation, membrane damage, and cell death. Ferroptosis is a regulated form of cell death characterized by the accumulation of lipid peroxides, which significantly inhibits the growth of ovarian cancer cells. SQLE is the primary enzyme responsible for catalyzing cholesterol lipid synthesis and is notably expressed in ovarian cancer tissues and cells. This study aims to investigate the role of squalene monooxygenase (SQLE) in ferroptosis in ovarian cancer. The protein and mRNA expression of SQLE was assessed using qRT-PCR, Western Blot, and immunohistochemistry. The association between SQLE and ferroptosis was demonstrated through analysis of TCGA and GTEx databases, TMT protein sequencing, as well as validation by qRT-PCR, Western Blot, immunofluorescence, ROS detection, and lipid peroxide detection. Animal experiments further confirmed the relationship between SQLE and ferroptosis in ovarian cancer. The protein and mRNA expression of SQLE was found to be upregulated in both ovarian cancer tissues and cell lines. Decreased SQLE expression led to ferroptosis in ovarian cancer cells, thereby increasing their sensitivity to ferroptosis inducers. Our research demonstrates that SQLE is significantly upregulated in both ovarian cancer tissues and cells. The overexpression of SQLE in ovarian cancer may facilitate tumorigenesis by conferring resistance to ferroptosis, thus shedding light on potential novel therapeutic strategies for ovarian cancer.

Cholesterol metabolism: physiological regulation and diseases

Cholesterol homeostasis is crucial for cellular and systemic function. The disorder of cholesterol metabolism not only accelerates the onset of cardiovascular disease (CVD) but is also the fundamental cause of other ailments. The regulation of cholesterol metabolism in the human is an extremely complex process. Due to the dynamic balance between cholesterol synthesis, intake, efflux and storage, cholesterol metabolism generally remains secure. Disruption of any of these links is likely to have adverse effects on the body. At present, increasing evidence suggests that abnormal cholesterol metabolism is closely related to various systemic diseases. However, the exact mechanism by which cholesterol metabolism contributes to disease pathogenesis remains unclear, and there are still unknown factors. In this review, we outline the metabolic process of cholesterol in the human body, especially reverse cholesterol transport (RCT). Then, we discuss separately the impact of abnormal cholesterol metabolism on common diseases and potential therapeutic targets for each disease, including CVD, tumors, neurological diseases, and immune system diseases. At the end of this review, we focus on the effect of cholesterol metabolism on eye diseases. In short, we hope to provide more new ideas for the pathogenesis and treatment of diseases from the perspective of cholesterol.