The lipogenic LXR-SREBF1 signaling pathway controls cancer cell DNA repair and apoptosis and is a vulnerable point of malignant tumors for cancer therapy

Radix Rehmanniae Praeparata extracts ameliorate hepatic ischemia-reperfusion injury by restoring lipid metabolism in hepatocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Hepatic ischemia/reperfusion injury (HIRI) is a common occurrence during or after liver surgery, representing a major cause for postoperative complications or increased morbidity and mortality in liver diseases. Rehmanniae Radix Praeparata (RRP) is a traditional Chinese medicine frequently used and has garnered extensive attention for its therapeutic potential treating cardiovascular and hepatic ailments. Recent studies have indicated the possibility of RRP in regulating lipid accumulation and apoptosis in hepatocytes.

AIM OF THE STUDY

This study aimed to investigate the specific mechanisms by which RRP may impede the progression of HIRI through the regulation of lipid metabolism.

MATERIALS AND METHODS

High-performance liquid chromatography (HPLC) was used to identify the major components of RRP water extract. C57BL/6J mice were orally given RRP at doses of 2.5 g/kg, 5 g/kg, and 10 g/kg for a duration of 7 days before undergoing HIRI surgery. Furthermore, we established a lipid-loaded in vitro model by exposing hepatocytes to oleic acid and palmitic acid (OAPA). The anti-HIRI effect of RRP was determined through transcriptomics and various molecular biology experiments.

RESULTS

After identifying active ingredients in RRP, we observed that RRP exerted lipid-lowering and hepatoprotective effects on HIRI mice and OAPA-treated hepatocytes. RRP activated AMP-activated protein kinase (AMPK) and inhibited mammalian target of rapamycin (mTOR), which further on the one hand, inhibited the cleavage and activation of sterol regulatory element binding protein 2 (SREBP2) by limiting the movement of SREBPs cleavage-activating protein (SCAP)-SREBP2 complex with the help of endoplasmic reticulum lipid raft-associated protein 1 (ERLIN1) and insulin-induced gene 1 (INSIG1), and on the other hand, promoted liver X receptor α (LXRα) nuclear transportation and subsequent cholesterol efflux. Meanwhile, the anti-lipotoxic effect of RRP can be partly reversed by an LXRα inhibitor but largely blocked by the application of compound C, an AMPK inhibitor.

CONCLUSION

Our study elucidated that RRP served as a potential AMPK activator to alleviate HIRI by blocking SREBP2 activation and cholesterol synthesis, while also activating LXRα to facilitate cholesterol efflux. These findings shed new light on the potential therapeutic use of RRP for improving HIRI.

Enhanced cancer cell proliferation and aggressive phenotype counterbalance in breast cancer with high BRCA1 gene expression

PURPOSE

While comprehensive research exists on the mutation of the DNA repair gene BRCA1, limited information is available regarding the clinical significance of BRCA1 gene expression. Given that cancer cell proliferation is aggrevated by DNA repair, we hypothesized that high BRCA1 gene expression breast cancer (BC) might be linked with aggressive tumor biology and poor clinical outcomes.

METHODS

The cohorts: The Cancer Genome Atlas (TCGA, n = 1069), METABRIC (n = 1903), and SCAN-B (n = 3273) were utilzed to obtain data of 6245 BC patients.

RESULTS

BC patients without BRCA1 mutation exhibited higher BRCA1 expression, which was associated with DNA repair functionality. However, no such correlation was observed with BRCA2 expression. The association of high BRCA1 expression with cancer cell proliferation was evidenced by significant enrichment of cell proliferation-related gene sets, higher histological grade, and proliferation score. Furthermore, increased levels of homologous recombination deficiency, intratumoral heterogeneity, and altered fractions were associated with high BRCA1 expression. Moreover, BC with high BRCA1 expression exhibited reduced infiltration of dendritic cells and CD8 T-cells, while showing increased infiltration of Th1 cells. Surprisingly, BRCA1 expression was not associated with the survival of BC irrespective of the subtypes. Conversely, BC with low BRCA1 expression enriched cancer aggravating pathway gene sets, such as Cancer Stem Cell-related signaling (NOTCH and HEDGEHOG), Angiogenesis, Epithelial-Mesenchymal Transition, Inflammatory Response, and TGF-beta signaling.

CONCLUSION

Despite being linked to heightened proliferation of cancer cells and unassertive phenotype, BRCA1 expression did not show any association with survival in BC.

Autocorrelation analysis of a phenotypic screen reveals hidden drug activity

Phenotype based screening is a powerful tool to evaluate cellular drug response. Through high content fluorescence imaging of simple fluorescent labels and complex image analysis phenotypic measurements can identify subtle compound-induced cellular changes unique to compound mechanisms of action (MoA). Recently, a screen of 1008 compounds in three cell lines was reported where analysis detected changes in cellular phenotypes and accurately identified compound MoA for roughly half the compounds. However, we were surprised that DNA alkylating agents and other compounds known to induce or impact the DNA damage response produced no measured activity in cells with fluorescently labeled 53BP1-a canonical DNA damage marker. We hypothesized that phenotype analysis is not sensitive enough to detect small changes in 53BP1 distribution and analyzed the screen images with autocorrelation image analysis. We found that autocorrelation analysis, which quantifies fluorescently-labeled protein clustering, identified higher compound activity for compounds and MoAs known to impact the DNA damage response, suggesting altered 53BP1 recruitment to damaged DNA sites. We then performed experiments under more ideal imaging settings and found autocorrelation analysis to be a robust measure of changes to 53BP1 clustering in the DNA damage response. These results demonstrate the capacity of autocorrelation to detect otherwise undetectable compound activity and suggest that autocorrelation analysis of specific proteins could serve as a powerful screening tool.

Cancer/testis-45A1 promotes cervical cancer cell tumorigenesis and drug resistance by activating oncogenic SRC and downstream signaling pathways

BACKGROUND

Cancer/testis antigen-45A1 (CT45A1) is overexpressed in various types of cancer but is not expressed in healthy women. The role of CT45A1 in cervical cancer has not yet been described in the literature.

PURPOSE

The aim of this research was to study the role of CT45A1 in cervical cancer progression and drug resistance, elucidate the mechanisms underlying CT45A1-mediated tumorigenesis and investigate CT45A1 as a biomarker for cervical cancer diagnosis, prognostic prediction, and targeted therapy.

METHODS

The CT45A1 levels in the tumors from cervical cancer patients were measured using immunohistochemical staining. The role and mechanisms underlying CT45A1-mediated cervical cancer cell tumor growth, invasion, and drug resistance were studied using xenograft mice, cervical cancer cells, immunohistochemistry, RNA-seq, real-time qPCR, Chromatin immunoprecipitation and Western blotting.

RESULTS

CT45A1 levels were notably high in the tumor tissues of human cervical cancer patients compared to the paracancerous tissues (p < 0.001). Overexpression of CT45A1 was closely associated with poor prognosis in cervical cancer patients. CT45A1 promoted cervical cancer cell tumor growth, invasion, neovascularization, and drug resistance. Mechanistically, CT45A1 promoted the expression of 128 pro-tumorigenic genes and concurrently activated key signaling pathways, including the oncogenic SRC, ERK, CREB, and YAP/TAZ signaling pathways. Furthermore, CT45A1-mediated tumorigenesis and drug resistance were markedly inhibited by the small molecule lycorine.

CONCLUSION

CT45A1 promotes cervical cancer cell tumorigenesis, neovascularization, and drug resistance by activating oncogenic SRC and downstream tumorigenic signaling pathways. These findings provide new insight into the pathogenesis of cervical cancer and offer a new platform for the development of novel therapeutics against cervical cancer.

Lipid Metabolism as a Potential Target of Liver Cancer

Hepatocellular carcinoma (HCC) stands as a severe malignant tumor with a profound impact on overall health, often accompanied by an unfavorable prognosis. Despite some advancements in the diagnosis and treatment of this disease, improving the prognosis of HCC remains a formidable challenge. It is noteworthy that lipid metabolism plays a pivotal role in the onset, development, and progression of tumor cells. Existing research indicates the potential application of targeting lipid metabolism in the treatment of HCC. This review aims to thoroughly explore the alterations in lipid metabolism in HCC, offering a detailed account of the potential advantages associated with innovative therapeutic strategies targeting lipid metabolism. Targeting lipid metabolism holds promise for potentially enhancing the prognosis of HCC.

Lycorine inhibits pancreatic cancer cell growth and neovascularization by inducing Notch1 degradation and downregulating key vasculogenic genes

Pancreatic cancer is highly metastatic and lethal with an increasing incidence globally and a 5-year survival rate of only 8%. One of the factors contributing to the high mortality is the lack of effective drugs in the clinical setting. We speculated that effective compounds against pancreatic cancer exist in natural herbs and explored active small molecules among traditional Chinese medicinal herbs. The small molecule lycorine (MW: 323.77) derived from the herb Lycoris radiata inhibited pancreatic cancer cell growth with an IC50 value of 1 μM in a concentration-dependent manner. Lycorine markedly reduced pancreatic cancer cell viability, migration, invasion, neovascularization, and gemcitabine resistance. Additionally, lycorine effectively suppressed tumor growth in mouse xenograft models without obvious toxicity. Pharmacological studies revealed that the levels and half-life of Notch1 oncoprotein in the pancreatic cancer cells Panc-1 and Patu8988 were notably reduced. Moreover, the expression of the key vasculogenic genes Semaphorin 4D (Sema4D) and angiopoietin-2 (Ang-2) were also significantly inhibited by lycorine. Mechanistically, lycorine strongly triggered the degradation of Notch1 oncoprotein through the ubiquitin-proteasome system. In conclusion, lycorine effectively inhibits pancreatic cancer cell growth, migration, invasion, neovascularization, and gemcitabine resistance by inducing degradation of Notch1 oncoprotein and downregulating the key vasculogenic genes Sema4D and Ang-2. Our findings provide a new therapeutic candidate and treatment strategy against pancreatic cancer.

RAI2 acts as a tumor suppressor with functional significance in gastric cancer

Metastasis of gastric cancer (GC) is one of the major causes of death among GC patients. GC metastasis involves numerous biological processes, yet the specific molecular biological mechanisms have not been elucidated. Here, we report a novel tumor suppressor, retinoic acid-induced 2 (RAI2), which is located in the Xp22 region of the chromosome and plays a role in inhibiting GC growth and invasion. In this study, integrated analysis of The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) datasets and immunohistochemistry staining data suggested that RAI2 expression in GC samples was low. Moreover, the immune infiltration analysis indicated that low expression of RAI2 in GC was associated with a higher intensity of tumor-infiltrating lymphocytes (TILs) and an abundance of Programmed death ligand 1 (PD-L1) expression. Gene set enrichment analysis (GSEA) analysis further revealed that RAI2 regulated some pathways including the GAP junction, focal adhesion and ECM receptor interaction pathway, immune regulation, PI3K-Akt signaling, MAPK signaling, cell cycle, and DNA replication. Furthermore, the knockdown of RAI2 promoted GC cell proliferation, migration, and invasion in vitro. Taken together, these results suggest that the tumor suppressor RAI2 could be a potential target for the development of anti-cancer strategies in GC.

Liver X receptors induce antiproliferative effects in basal-like breast cancer

Liver X receptors (LXRs) are nuclear transcription factors important in the regulation of cholesterol transport, and glucose and fatty acid metabolism. The antiproliferative role of LXRs has been studied in a variety of malignancies and may represent a therapeutic opportunity in cancers lacking targeted therapies, such as triple-negative breast cancer. In this study, we investigated the impact of LXR agonists alone and in combination with carboplatin in preclinical models of breast cancer. In vitro experiments revealed a dose-dependent decrease in tumor cell proliferation in estrogen receptor-positive breast cancer cells, whereas LXR activation in vivo resulted in an increased growth inhibitory effect in a basal-like breast cancer model (in combination with carboplatin). Functional proteomic analysis identified differences in protein expression between responding and nonresponding models related to Akt activity, cell-cycle progression, and DNA repair. Furthermore, pathway analysis suggested that the LXR agonist in combination with carboplatin inhibits the activity of targets of E2F transcription factors and affects cholesterol homeostasis in basal-like breast cancer.

Emerging Insights into Liver X Receptor α in the Tumorigenesis and Therapeutics of Human Cancers

Liver X receptor α (LXRα), a member of the nuclear receptor superfamily, is identified as a protein activated by ligands that interacts with the promoters of specific genes. It regulates cholesterol, bile acid, and lipid metabolism in normal physiological processes, and it participates in the development of some related diseases. However, many studies have demonstrated that LXRα is also involved in regulating numerous human malignancies. Aberrant LXRα expression is emerging as a fundamental and pivotal factor in cancer cell proliferation, invasion, apoptosis, and metastasis. Herein, we outline the expression levels of LXRα between tumor tissues and normal tissues via the Oncomine and Tumor Immune Estimation Resource (TIMER) 2.0 databases; summarize emerging insights into the roles of LXRα in the development, progression, and treatment of different human cancers and their diversified mechanisms; and highlight that LXRα can be a biomarker and therapeutic target in diverse cancers.

The long non-coding RNA keratin-7 antisense acts as a new tumor suppressor to inhibit tumorigenesis and enhance apoptosis in lung and breast cancers

Expression of the long non-coding RNA (lncRNA) keratin-7 antisense (KRT7-AS) is downregulated in various types of cancer; however, the impact of KRT7-AS deficiency on tumorigenesis and apoptosis is enigmatic. We aim to explore the influence of KRT7-AS in carcinogenesis and apoptosis. We found that KRT7-AS was deficient in breast and lung cancers, and low levels of KRT7-AS were a poor prognostic factor in breast cancer. Cellular studies showed that silencing of KRT7-AS in lung cancer cells increased oncogenic Keratin-7 levels and enhanced tumorigenesis, but diminished cancer apoptosis of the cancer cells; by contrast, overexpression of KRT7-AS inhibited lung cancer cell tumorigenesis. Additionally, KRT7-AS sensitized cancer cells to the anti-cancer drug cisplatin, consequently enhancing cancer cell apoptosis. In vivo, KRT7-AS overexpression significantly suppressed tumor growth in xenograft mice, while silencing of KRT7-AS promoted tumor growth. Mechanistically, KRT7-AS reduced the levels of oncogenic Keratin-7 and significantly elevated amounts of the key tumor suppressor PTEN in cancer cells through directly binding to PTEN protein via its core nucleic acid motif GGCAAUGGCGG. This inhibited the ubiquitination-proteasomal degradation of PTEN protein, therefore elevating PTEN levels in cancer cells. We also found that KRT7-AS gene transcription was driven by the transcription factor RXRα; intriguingly, the small molecule berberine enhanced KRT7-AS expression, reduced tumorigenesis, and promoted apoptosis of cancer cells. Collectively, KRT7-AS functions as a new tumor suppressor and an apoptosis enhancer in lung and breast cancers, and we unraveled that the RXRα-KRT7-AS-PTEN signaling axis controls carcinogenesis and apoptosis. Our findings highlight a tumor suppressive role of endogenous KRT7-AS in cancers and an important effect the RXRα-KRT7-AS-PTEN axis on control of cancer cell tumorigenesis and apoptosis, and offer a new platform for developing novel therapeutics against cancers.

Mechanisms of obesity- and diabetes mellitus-related pancreatic carcinogenesis: a comprehensive and systematic review

Research on obesity- and diabetes mellitus (DM)-related carcinogenesis has expanded exponentially since these two diseases were recognized as important risk factors for cancers. The growing interest in this area is prominently actuated by the increasing obesity and DM prevalence, which is partially responsible for the slight but constant increase in pancreatic cancer (PC) occurrence. PC is a highly lethal malignancy characterized by its insidious symptoms, delayed diagnosis, and devastating prognosis. The intricate process of obesity and DM promoting pancreatic carcinogenesis involves their local impact on the pancreas and concurrent whole-body systemic changes that are suitable for cancer initiation. The main mechanisms involved in this process include the excessive accumulation of various nutrients and metabolites promoting carcinogenesis directly while also aggravating mutagenic and carcinogenic metabolic disorders by affecting multiple pathways. Detrimental alterations in gastrointestinal and sex hormone levels and microbiome dysfunction further compromise immunometabolic regulation and contribute to the establishment of an immunosuppressive tumor microenvironment (TME) for carcinogenesis, which can be exacerbated by several crucial pathophysiological processes and TME components, such as autophagy, endoplasmic reticulum stress, oxidative stress, epithelial-mesenchymal transition, and exosome secretion. This review provides a comprehensive and critical analysis of the immunometabolic mechanisms of obesity- and DM-related pancreatic carcinogenesis and dissects how metabolic disorders impair anticancer immunity and influence pathophysiological processes to favor cancer initiation.

Triptonide Ameliorates Middle Cerebral Artery Occlusion-induced Cerebral Ischemic Damage in Rats via Regulation of In flammatory Response

Background

Cerebral ischemic stroke is the second major cause of mortality worldwide that results in persisting disability and mental agony. Ischemic stroke is induced by the diminished blood circulation to the brain, which can be due to obstruction by arteriosclerosis, fibromuscular dysplasia, or thrombosis. Triptonide is a diterpene triepoxide, purified out of extracts of Tripterygium wilfordii Hook F, and is an emerging target against, for example, cancers and inflammatory insults.

Materials and Methods

Taking this into consideration, this study was designed to analyze the effect of triptonide on ischemic/reperfusion (I/R) cerebral infarction stroke rats.

Results

Our study showed that triptonide decreased the infarct volume and brain edema produced by I/R. Moreover, triptonide protected the rats from any neurological deficits, which were analyzed using a five-point scoring system, augmented antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione content, and lowered the activity of acetylcholinesterase. Triptonide also decreased the levels of pro-inflammatory cytokines such as interleukin-1 β (IL-1 β), TNF- α, and IL-6, while it augmented anti-inflammatory cytokines IL-10 and vascular endothelial growth factor. In this study, cerebral infarction stroke rats showed an increase in malondialdehyde levels. Triptonide preserved the normal brain architecture from various neurotoxic effects.

Conclusion

Thus, triptonide can be targeted for drug discovery in the future to protect against cerebral infarction stroke.

The Cancer/Testis Antigen CT45A1 Promotes Transcription of Oncogenic Sulfatase-2 Gene in Breast Cancer Cells and Is Sensible Targets for Cancer Therapy

PURPOSE

Invasive breast carcinomas (BRCAs) are highly lethal. The molecular mechanisms underlying progression of invasive BRCAs are unclear, and effective therapies are highly desired. The cancer-testis antigen CT45A1 promotes overexpression of pro-metastatic sulfatase-2 (SULF2) and breast cancer metastasis to the lungs, but its mechanisms are largely unknown. In this study, we aimed to elucidate the mechanism of CT45A1-induced SULF2 overexpression and provide evidence for targeting CT45A1 and SULF2 for breast cancer therapy.

METHODS

The effect of CT45A1 on SULF2 expression was assessed using reverse transcription polymerase chain reaction and western blot. The mechanism of CT45A1-induced SULF2 gene transcription was studied using protein-DNA binding assay and a luciferase activity reporter system. The interaction between CT45A1 and SP1 proteins was assessed using immunoprecipitation and western blot. Additionally, the suppression of breast cancer cell motility by SP1 and SULF2 inhibitors was measured using cell migration and invasion assays.

RESULTS

CT45A1 and SULF2 are aberrantly overexpressed in patients with BRCA; importantly, overexpression of CT45A1 is closely associated with poor prognosis. Mechanistically, gene promoter demethylation results in overexpression of both CT45A1 and SULF2. CT45A1 binds directly to the core sequence GCCCCC in the promoter region of SULF2 gene and activates the promoter. Additionally, CT45A1 interacts with the oncogenic master transcription factor SP1 to drive SULF2 gene transcription. Interestingly, SP1 and SULF2 inhibitors suppress breast cancer cell migration, invasion, and tumorigenicity.

CONCLUSION

Overexpression of CT45A1 is associated with poor prognosis in patients with BRCA. CT45A1 promotes SULF2 overexpression by activating the promoter and interacting with SP1. Additionally, SP1 and SULF2 inhibitors suppress breast cancer cell migration, invasion, and tumorigenesis. Our findings provide new insight into the mechanisms of breast cancer metastasis and highlight CT45A1 and SULF2 as sensible targets for developing novel therapeutics against metastatic breast cancer.

A vasculogenic mimicry prognostic signature associated with immune signature in human gastric cancer

Background

Gastric cancer (GC) is one of the most lethal malignant tumors worldwide with poor outcomes. Vascular mimicry (VM) is an alternative blood supply to tumors that is independent of endothelial cells or angiogenesis. Previous studies have shown that VM was associated with poor prognosis in patients with GC, but the underlying mechanisms and the relationship between VM and immune infiltration of GC have not been well studied.

Methods

In this study, expression profiles from VM-related genes were retrieved from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Cox regression was performed to identify key VM-related genes for survival. Subsequently, a novel risk score model in GC named VM index and a nomogram was constructed. In addition, the expression of one key VM-related gene (serpin family F member 1, SERPINF1) was validated in 33 GC tissues and 23 paracancer tissues using immunohistochemistry staining.

Results

Univariate and multivariate Cox regression suggested that SERPINF1 and tissue factor pathway inhibitor 2 (TFPI2) were independent risk factors for the prognosis of patients with GC. The AUC (> 0.7) indicated the satisfactory discriminative ability of the nomogram. SsGESA and ESTIMATE showed that higher expression of SERPINF1 and TFPI2 is associated with immune infiltration of GC. Immunohistochemistry staining confirmed that the expression of SERPINF1 protein was significantly higher in GC tissues than that in paracancer tissues.

Conclusion

A VM index and a nomogram were constructed and showed satisfactory predictive performance. In addition, VM was confirmed to be widely involved in immune infiltration, suggesting that VM could be a promising target in guiding immunotherapy. Taken together, we identified SERPINF1 and TFPI2 as immunologic and prognostic biomarkers related to VM in GC.

The Impact of Oxidative Stress and AKT Pathway on Cancer Cell Functions and Its Application to Natural Products

Oxidative stress and AKT serine-threonine kinase (AKT) are responsible for regulating several cell functions of cancer cells. Several natural products modulate both oxidative stress and AKT for anticancer effects. However, the impact of natural product-modulating oxidative stress and AKT on cell functions lacks systemic understanding. Notably, the contribution of regulating cell functions by AKT downstream effectors is not yet well integrated. This review explores the role of oxidative stress and AKT pathway (AKT/AKT effectors) on ten cell functions, including apoptosis, autophagy, endoplasmic reticulum stress, mitochondrial morphogenesis, ferroptosis, necroptosis, DNA damage response, senescence, migration, and cell-cycle progression. The impact of oxidative stress and AKT are connected to these cell functions through cell function mediators. Moreover, the AKT effectors related to cell functions are integrated. Based on this rationale, natural products with the modulating abilities for oxidative stress and AKT pathway exhibit the potential to regulate these cell functions, but some were rarely reported, particularly for AKT effectors. This review sheds light on understanding the roles of oxidative stress and AKT pathway in regulating cell functions, providing future directions for natural products in cancer treatment.

Lipid metabolism in pancreatic cancer: emerging roles and potential targets

Pancreatic cancer is one of the most serious health issues in developed and developing countries, with a 5-year overall survival rate currently <9%. Patients typically present with advanced disease due to vague symptoms or lack of screening for early cancer detection. Surgical resection represents the only chance for cure, but treatment options are limited for advanced diseases, such as distant metastatic or locally progressive tumors. Although adjuvant chemotherapy has improved long-term outcomes in advanced cancer patients, its response rate is low. So, exploring other new treatments is urgent. In recent years, increasing evidence has shown that lipid metabolism can support tumorigenesis and disease progression as well as treatment resistance through enhanced lipid synthesis, storage, and catabolism. Therefore, a better understanding of lipid metabolism networks may provide novel and promising strategies for early diagnosis, prognosis estimation, and targeted therapy for pancreatic cancer patients. In this review, we first enumerate and discuss current knowledge about the advances made in understanding the regulation of lipid metabolism in pancreatic cancer. In addition, we summarize preclinical studies and clinical trials with drugs targeting lipid metabolic systems in pancreatic cancer. Finally, we highlight the challenges and opportunities for targeting lipid metabolism pathways through precision therapies in pancreatic cancer.

Targeting SREBP-1-Mediated Lipogenesis as Potential Strategies for Cancer

Sterol regulatory element binding protein-1 (SREBP-1), a transcription factor with a basic helix–loop–helix leucine zipper, has two isoforms, SREBP-1a and SREBP-1c, derived from the same gene for regulating the genes of lipogenesis, including acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase. Importantly, SREBP-1 participates in metabolic reprogramming of various cancers and has been a biomarker for the prognosis or drug efficacy for the patients with cancer. In this review, we first introduced the structure, activation, and key upstream signaling pathway of SREBP-1. Then, the potential targets and molecular mechanisms of SREBP-1-regulated lipogenesis in various types of cancer, such as colorectal, prostate, breast, and hepatocellular cancer, were summarized. We also discussed potential therapies targeting the SREBP-1-regulated pathway by small molecules, natural products, or the extracts of herbs against tumor progression. This review could provide new insights in understanding advanced findings about SREBP-1-mediated lipogenesis in cancer and its potential as a target for cancer therapeutics.

Triptonide effectively inhibits triple-negative breast cancer metastasis through concurrent degradation of Twist1 and Notch1 oncoproteins

Background

Triple-negative breast cancer (TNBC) is highly metastatic and lethal. Due to a lack of druggable targets for this disease, there are no effective therapies in the clinic.

Methods

We used TNBC cells and xenografted mice as models to explore triptonide-mediated inhibition of TNBC metastasis and tumor growth. Colony formation assay was used to quantify the tumorigenesis of TNBC cells. Wound-healing and cell trans-well assays were utilized to measure cell migration and invasion. Tube formation assay was applied to access tumor cell-mediated vasculogenic mimicry. Western blot, quantitative-PCR, immunofluorescence imaging, and immunohistochemical staining were used to measure the expression levels of various tumorigenic genes in TNBC cells.

Results

Here, we showed that triptonide, a small molecule from the traditional Chinese medicinal herb Tripterygium wilfordii Hook F, potently inhibited TNBC cell migration, invasion, and vasculogenic mimicry, and effectively suppressed TNBC tumor growth and lung metastasis in xenografted mice with no observable toxicity. Molecular mechanistic studies revealed that triptonide strongly triggered the degradation of master epithelial-mesenchymal transition (EMT)-inducing protein Twist1 through the lysosomal system and reduced Notch1 expression and NF-κB phosphorylation, which consequently diminished the expression of pro-metastatic and angiogenic genes N-cadherin, VE-cadherin, and vascular endothelial cell growth factor receptor 2 (VEGFR2).

Conclusions

Triptonide effectively suppressed TNBC cell tumorigenesis, vasculogenic mimicry, and strongly inhibited the metastasis of TNBC via degradation of Twist1 and Notch1 oncoproteins, downregulation of metastatic and angiogenic gene expression, and reduction of NF-κB signaling pathway. Our findings provide a new strategy for treating highly lethal TNBC and offer a potential new drug candidate for combatting this aggressive disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01488-7.

Microchamber-Free Digital Flow Cytometric Analysis of T4 Polynucleotide Kinase Phosphatase Based on Single-Enzyme-to-Single-Bead Space-Confined Reaction

Digital bioassays have attracted extensive attention in biomedical applications due to their ultrahigh sensitivity. However, traditional digital bioassays require numerous microchambers such as droplets or microwells, which restricts their application scope. Herein, we propose a microchamber-free flow cytometric method for the digital quantification of T4 polynucleotide kinase phosphatase (T4 PNKP) based on an unprecedented phenomenon that each T4 PNKP molecule-catalyzed reaction can be spatially self-confined on a single microbead, which ultimately enables the one-target-to-one-fluorescence-positive microbead digital signal transduction. The digital signal-readout mode can clearly detect T4 PNKP concentrations as low as 1.28 × 10^-10 U/μL, making it most sensitive method to date. Significantly, T4 PNKP can be specifically distinguished from other phosphatases and nucleases in complex samples by digitally counting the fluorescence-positive microbeads, which cannot be realized by traditional bulk measurement-based methods. Taking advantage of the novel space-confined enzymatic feature of T4 PNKP, this digital mechanism can use T4 PNKP as the enzyme label to fabricate digital sensing systems toward various biomolecules such as digital enzyme-linked immunosorbent assay (ELISA). Therefore, this work not only enlarges the toolbox for high-sensitivity biomolecule detection but also opens new gates to fabricate next-generation digital assays.

Molecular mechanism of liver X receptors in cancer therapeutics

Liver X receptors (LXRs) are receptors that belong to the nuclear receptor superfamily (NRs). It was originally called the "orphan receptor" when it was firstly discovered. Then it was found to be activated by oxysterol and it was officially named LXRs. LXRs are activated by ligands and bind to the retinol X receptor to form a heterodimer and regulate metabolism. Numerous studies have shown that LXRs are involved in regulating immune function and maintaining immune tolerance. Activating LXRs can also inhibit the tumorigenesis and promote apoptosis of tumor cells, which make LXRs as potential targets in cancer treatment. This review will discuss the recent progress of LXRs from the structure and function of LXRs, the signaling pathway of LXRs, the molecular mechanism of LXRs activation in cancers, and the potential targets of LXRs in cancer therapy.

MicroRNA-325 facilitates atherosclerosis progression by mediating the SREBF1/LXR axis via KDM1A

AIMS

MicroRNA-325 (miR-325) was significantly upregulated in diabetic atherosclerosis, while its specific role in atherosclerosis has not been established. The present study was set to probe the effects of miR-325 on the atherosclerosis progression and to explore the mechanisms.

MATERIALS AND METHODS

The ApoE^-/- mouse with atherosclerosis was developed to detect the miR-325 expression in atherosclerotic plaques. The pathological symptoms of atherosclerotic mice were observed by injection of miR-325 mimic or inhibitor. Subsequently, the levels of CRP, IL-6, IL-1β and TNF-ɑ in mouse serum were measured by ELISA. Then, miR-325 was overexpressed or silenced in RAW264.7-derived foam cells (FCs), and cholesterol efflux and lipid content were evaluated. Furthermore, miR-325 expression was altered in HA-VSMCs to measure viability and apoptosis. The targets of miR-325 were predicted in a bioinformatics website, and the expression of KDM1A, SREBF1 and PPARγ-LXR-ABCA1 in mouse arterial tissues and cells was detected, followed by rescue experiments.

KEY FINDINGS

miR-325 was elevated in arterial tissues of atherosclerotic mice, and miR-325 inhibition in mice reduced the contents of total cholesterol, triglyceride, low-density lipoprotein, and CRP, IL-6, IL-1β and TNF-ɑ levels in mouse serum. miR-325 inhibitor facilitated the cholesterol efflux and decreased the lipid content in RAW264.7 cells, and also diminished HA-VSMC viability. miR-325 targeted KDM1A to reduce SREBF1 expression, and further KDM1A suppression inhibited cholesterol efflux in RAW264.7 cells and the activation of PPARγ-LXR-ABCA1 pathway.

SIGNIFICANCE

miR-325 lowers SREBF1 expression by decreasing KDM1A expression, thereby inhibiting the activation of the PPARγ-LXR-ABCA1 pathway and thus promoting atherosclerosis.

Activation of the tumor suppressive Hippo pathway by triptonide as a new strategy to potently inhibit aggressive melanoma cell metastasis

Metastatic melanoma has a very high mortality rate despite the availability of chemotherapy, radiotherapy, and immunotherapy; therefore, more effective therapeutics are needed. The Hippo pathway plays an inhibitory role in melanoma progression, but the tumor suppressors Salvador homolog-1 (SAV1) and large tumor suppressor 1 (LATS1) in this pathway are down-regulated in melanoma. As a result, the downstream oncogenic Yes-associated protein (YAP) is active, resulting in uncontrolled melanoma growth and metastasis. Therapeutics for remedying SAV1 and LATS1 deficiency in melanoma have not yet been reported in the literature. Here, we show that the small molecule triptonide (MW 358 Da) robustly suppressed melanoma cell tumorigenicity, migration, and invasion. Furthermore, triptonide markedly reduced tumor growth and melanoma lung metastasis in tumor-bearing mice with low toxicity. Molecular mechanistic studies revealed that triptonide promoted SAV1 and LATS1 expression, strongly activated the tumor-suppressive Hippo pathway, degraded oncogenic YAP via the lysosomal pathway, and reduced levels of tumorigenic microphthalmia-associated transcription factor (MITF) in melanoma cells. Triptonide also strongly inhibited activation of AKT, a SAV1-binding signaling protein. Collectively, our results conceptually demonstrate that induction of SAV1 and LATS1 expression and activation of the tumor-suppressive Hippo pathway by triptonide potently inhibits aggressive melanoma cell growth and metastasis. These findings suggest a new strategy for developing therapeutics to treat metastatic melanoma and highlight a novel drug candidate against aggressive melanoma.