The mevalonate pathway in breast cancer biology

Cancer cell stiffening via CoQ10 and UBIAD1 regulates ECM signaling and ferroptosis in breast cancer

CoQ10 (Coenzyme Q10) is an essential fat-soluble metabolite that plays a key role in cellular metabolism. A less-known function of CoQ10 is whether it may act as a plasma membrane-stabilizing agent and whether this property can affect cancer development and progression. Here, we show that CoQ10 and its biosynthetic enzyme UBIAD1 play a critical role in plasmamembrane mechanical properties that are of interest for breast cancer (BC) progression and treatment. CoQ10 and UBIAD1 increase membrane fluidity leading to increased cell stiffness in BC. Furthermore, CoQ10 and UBIAD1 states impair ECM (extracellular matrix)-mediated oncogenic signaling and reduce ferroptosis resistance in BC settings. Analyses on human patients and mouse models reveal that UBIAD1 loss is associated with BC development and progression and UBIAD1 expression in BC limits CTCs (circulating tumor cells) survival and lung metastasis formation. Overall, this study reveals that CoQ10 and UBIAD1 can be further investigated to develop therapeutic interventions to treat BC patients with poor prognosis.

Sensitive quantification of mevalonate pathway intermediates and prediction of relative novel analogs by chemical derivatization-based LC-MS/MS

The mevalonate (MVA) pathway plays a crucial role in the occurrence and progression of various diseases, such as osteoporosis, breast cancer, and lung cancer, etc. However, determining all the MVA pathway intermediates is still challenging due to their high polarity, low concentration, chelation effect with metal compartments, and poor mass spectrometric response. In this study, we established a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method coupled with N2, N2, N4, N4-tetramethyl-6-(4-(piperazin-1-ylsulfonyl) phenyl)-1,3,5-triazine-2,4-diamine (Tmt-PP) labeling for the simultaneous analysis of all MVA intermediates in biospecimens. Chemical derivatization significantly improved the chromatographic retention, peak shape, and detection sensitivity of the analytes. Moreover, we employed a method named mass spectrum calculation to achieve the absolute quantification of the isomers, i.e., isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). The established method was fully qualified and applied to explore the difference of these metabolites in cisplatin-resistant non-small cell lung cancer (NSCLC) cells. Additionally, several MVA intermediate analogs, including isopentenyl monophosphate or dimethylallyl monophosphate (IMP/DMAMP), geranyl monophosphate (GMP), 5-triphosphomevalonate (MTP), and isopentenyl triphosphate or dimethylallyl triphosphate (ITP/DMATP), were identified for the first time using a knowledge-driven prediction strategy. We further explored the tissue distribution of these novel metabolites. Overall, this work developed a sensitive quantification method for all MVA intermediates, which will enhance our understanding of the role of this pathway in various health and disease conditions. The novel metabolites we discovered warrant further investigations into their biosynthesis and biological functions.

Aptamer functionalized hypoxia-potentiating agent and hypoxia-inducible factor inhibitor combined with hypoxia-activated prodrug for enhanced tumor therapy

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. Hypoxia-activated prodrugs (HAPs) have shown promise as potential therapeutic agents for TNBC. While increasing hypoxia levels may promote the HAP activation, it raises concerns regarding HIF1α-dependent drug resistance. It is desirable to develop a targeted approach that enhances tumor hypoxia for HAP activation without promoting HIF1α-dependent drug resistance in TNBC treatment. Herein, we proposed a multi-responsive carrier-free self-assembled nanomedicine named AQ4N@CA4T1ASO. This nanomedicine first targeted tumors by the TNBC-targeting aptamers (T1), and then disassembled in the reductive and acidic conditions within tumors. The released Combretastatin 4 (CA4) could exacerbate hypoxia, thereby promoting the conversion of inactive Banoxantrone (AQ4N) to its active form, AQ4. Simultaneously, the released antisense oligonucleotide (ASO) could attenuate hypoxia-induced HIF1α mRNA expression, thereby sensitizing the tumor to chemotherapy. Overall, this smart nanomedicine represents a profound targeted therapy strategy, combining "hypoxia-potentiating, hypoxia-activated, chemo-sensitization" approaches for TNBC treatment. In vivo study demonstrated significant suppression of tumor growth, highlighting the promising potential of this nanomedicine for future clinical translation.

The mevalonate pathway contributes to breast primary tumorigenesis and lung metastasis

The mevalonate pathway plays an important role in breast cancer and other tumor types. However, many issues remain obscure as yet regarding its mechanism of regulation and action. In the present study, we report that the expression of mevalonate pathway enzymes is mediated by the RHO guanosine nucleotide exchange factors VAV2 and VAV3 in a RAC1- and sterol regulatory element-binding factor (SREBF)-dependent manner in breast cancer cells. Furthermore, in vivo tumorigenesis experiments indicated that the two most upstream steps of this metabolic pathway [3-hydroxy-3-methylglutaryl-coenzyme A synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR)] are important for primary tumorigenesis, angiogenesis, and cell survival in breast cancer cells. HMGCR, but not HMGCS1, is also important for the extravasation and subsequent fitness of breast cancer cells in the lung parenchyma. Genome-wide expression analyses revealed that HMGCR influences the expression of gene signatures linked to proliferation, metabolism, and immune responses. The HMGCR-regulated gene signature predicts long-term tumor recurrence but not metastasis in cohorts of nonsegregated and chemotherapy-resistant breast cancer patients. These results reveal a hitherto unknown, VAV-catalysis-dependent mechanism involved in the regulation of the mevalonate pathway in breast cancer cells. They also identify specific mevalonate-pathway-dependent processes that contribute to the malignant features of breast cancer cells.

Ferroptosis defense mechanisms: The future and hope for treating osteosarcoma

Currently, challenges such as chemotherapy resistance, resulting from preoperative and postoperative chemotherapy, postoperative recurrence, and poor bone regeneration quality, are becoming increasingly prominent in osteosarcoma (OS) treatment. There is an urgent need to find more effective ways to address these issues. Ferroptosis is a novel form of iron-dependent programmed cell death, distinct from other forms of cell death. In this paper, we summarize how, through the three major defense systems of ferroptosis, not only can substances from traditional Chinese medicine, antitumor drugs, and nano-drug carriers induce ferroptosis in OS cells, but they can also be combined with immunotherapy, differentiation therapy, and other treatment modalities to significantly enhance chemotherapy sensitivity and inhibit tumor growth. Thus, ferroptosis holds great potential in treating OS, offering more choices and possibilities for future clinical interventions.

Regulation of lipid metabolism by E3 ubiquitin ligases in lipid-associated metabolic diseases

Previous studies have progressively elucidated the involvement of E3 ubiquitin (Ub) ligases in regulating lipid metabolism. Ubiquitination, facilitated by E3 Ub ligases, modifies critical enzymes in lipid metabolism, enabling them to respond to specific signals. In this review, we aim to present a comprehensive analysis of the role of E3 Ub ligases in lipid metabolism, which includes lipid synthesis and lipolysis, and their influence on cellular lipid homeostasis through the modulation of lipid uptake and efflux. Furthermore, it explores how the ubiquitination process governs the degradation or activation of pivotal enzymes, thereby regulating lipid metabolism at the transcriptional level. Perturbations in lipid metabolism have been implicated in various diseases, including hepatic lipid metabolism disorders, atherosclerosis, diabetes, and cancer. Therefore, this review focuses on the association between E3 Ub ligases and lipid metabolism in lipid-related diseases, highlighting enzymes critically involved in lipid synthesis and catabolism, transcriptional regulators, lipid uptake translocators, and transporters. Overall, this review aims to identify gaps in current knowledge, highlight areas requiring further research, offer potential targeted therapeutic approaches, and provide a comprehensive outlook on clinical conditions associated with lipid metabolic diseases.

Impact of De Novo Cholesterol Biosynthesis on the Initiation and Progression of Breast Cancer

Cholesterol (CHOL) is a multifaceted lipid molecule. It is an essential structural component of cell membranes, where it cooperates in regulating the intracellular trafficking and signaling pathways. Additionally, it serves as a precursor for vital biomolecules, including steroid hormones, isoprenoids, vitamin D, and bile acids. Although CHOL is normally uptaken from the bloodstream, cells can synthesize it de novo in response to an increased requirement due to physiological tissue remodeling or abnormal proliferation, such as in cancer. Cumulating evidence indicated that increased CHOL biosynthesis is a common feature of breast cancer and is associated with the neoplastic transformation of normal mammary epithelial cells. After an overview of the multiple biological activities of CHOL and its derivatives, this review will address the impact of de novo CHOL production on the promotion of breast cancer with a focus on mammary stem cells. The review will also discuss the effect of de novo CHOL production on in situ and invasive carcinoma and its impact on the response to adjuvant treatment. Finally, the review will discuss the present and future therapeutic strategies to normalize CHOL biosynthesis.

Temozolomide, Simvastatin and Acetylshikonin Combination Induces Mitochondrial-Dependent Apoptosis in GBM Cells, Which Is Regulated by Autophagy

Glioblastoma multiforme (GBM) is one of the deadliest cancers. Temozolomide (TMZ) is the most common chemotherapy used for GBM patients. Recently, combination chemotherapy strategies have had more effective antitumor effects and focus on slowing down the development of chemotherapy resistance. A combination of TMZ and cholesterol-lowering medications (statins) is currently under investigation in in vivo and clinical trials. In our current investigation, we have used a triple-combination therapy of TMZ, Simvastatin (Simva), and acetylshikonin, and investigated its apoptotic mechanism in GBM cell lines (U87 and U251). We used viability, apoptosis, reactive oxygen species, mitochondrial membrane potential (MMP), caspase-3/-7, acridine orange (AO) and immunoblotting autophagy assays. Our results showed that a TMZ/Simva/ASH combination therapy induced significantly more apoptosis compared to TMZ, Simva, ASH, and TMZ/Simva treatments in GBM cells. Apoptosis via TMZ/Simva/ASH treatment induced mitochondrial damage (increase of ROS, decrease of MMP) and caspase-3/7 activation in both GBM cell lines. Compared to all single treatments and the TMZ/Simva treatment, TMZ/Simva/ASH significantly increased positive acidic vacuole organelles. We further confirmed that the increase of AVOs during the TMZ/Simva/ASH treatment was due to the partial inhibition of autophagy flux (accumulation of LC3β-II and a decrease in p62 degradation) in GBM cells. Our investigation also showed that TMZ/Simva/ASH-induced cell death was depended on autophagy flux, as further inhibition of autophagy flux increased TMZ/Simva/ASH-induced cell death in GBM cells. Finally, our results showed that TMZ/Simva/ASH treatment potentially depends on an increase of Bax expression in GBM cells. Our current investigation might open new avenues for a more effective treatment of GBM, but further investigations are required for a better identification of the mechanisms.

VIM‑AS1 promotes proliferation and drives enzalutamide resistance in prostate cancer via IGF2BP2‑mediated HMGCS1 mRNA stabilization

VIM‑AS1, a cancer‑specific long non‑coding RNA, has been recognized as a pivotal regulator in multiple types of cancer. However, the role of VIM‑AS1 in the proliferation and resistance to anti‑androgen therapy of LNCaP and C4‑2 prostate cancer cells remains to be determined. In the current study, gain‑and‑loss experiments were used to investigate the effects of VIM‑AS on the proliferation and anti‑androgen therapy of LNCaP and C4‑2 cells. RNA sequencing, RNA pulldown and RNA immunoprecipitation were used to elucidate the underlying mechanism of VIM‑AS1 driving prostate progression. It was demonstrated that VIM‑AS1 was upregulated in C4‑2 cells, an established castration‑resistant prostate cancer (CRPC) cell line, compared with in LNCaP cells, an established hormone‑sensitive prostate cancer cell line. The present study further demonstrated that VIM‑AS1 was positively associated with the clinical stage of prostate cancer. Functionally, overexpression of VIM‑AS1 decreased the sensitivity to enzalutamide treatment and enhanced the proliferation of LNCaP cells in vitro, whereas knockdown of VIM‑AS1 increased the sensitivity to enzalutamide treatment and reduced the proliferation of C4‑2 cells in vitro and in vivo. Mechanistically, 3‑hydroxy‑3‑methylglutaryl‑CoA synthase 1 (HMGCS1) was identified as one of the direct downstream targets of VIM‑AS1, and VIM‑AS1 promoted HMGCS1 expression by enhancing HMGCS1 mRNA stability through a VIM‑AS1/insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2)/HMGCS1 RNA‑protein complex. Rescue assays indicated that knockdown of HMGCS1 expression ameliorated the increase in proliferation and enzalutamide resistance of prostate cancer cells induced by VIM‑AS1 overexpression. Overall, the present study determined the roles and mechanism of the VIM‑AS1/IGF2BP2/HMGCS1 axis in regulating proliferation and enzalutamide sensitivity of prostate cancer cells and suggested that VIM‑AS1 may serve as a novel therapeutic target for the treatment of patients with CRPC.

Mutant p53 driven-LINC00857, a protein scaffold between FOXM1 and deubiquitinase OTUB1, promotes the metastasis of pancreatic cancer

Tumour metastasis is the major adverse factor for recurrence and death in pancreatic cancer (PC) patients. P53 mutations are considered to be the second most common type of mutation in PC and significantly promote PC metastasis. However, the molecular mechanisms underlying the effects of p53 mutations, especially the regulatory relationship of the protein with long noncoding RNAs (lncRNAs), remain unclear. In the present study, we demonstrated that the lncRNA LINC00857 exhibits a significantly elevated level in PC and that it is associated with poor prognosis; furthermore, TCGA data showed that LINC00857 expression was significantly upregulated in the mutant p53 group compared with the wild-type p53 group. Gain- and loss-of-function experiments showed that LINC00857 promotes the metastasis of PC cells. We further found that LINC00857 upregulates FOXM1 protein expression and thus accelerates metastasis in vitro and in vivo. Mechanistically, LINC00857 bound simultaneously to FOXM1 and to the deubiquitinase OTUB1, thereby serving as a protein scaffold and enhancing the interaction between FOXM1 and OTUB1, which inhibits FOXM1 degradation through the ubiquitin-proteasome pathway. Interestingly, we found that mutant p53 promotes LINC00857 transcription by binding to its promoter region. Finally, atorvastatin, a commonly prescribe lipid-lowering drug, appeared to inhibit PC metastasis by inhibiting the mutant p53-LINC00857 axis. Taken together, our results provide new insights into the biology driving PC metastasis and indicate that the mutant p53-LINC00857 axis might represent a novel therapeutic target for PC metastasis.