MMAB promotes negative feedback control of cholesterol homeostasis

Multiomic profiling of breast cancer cells uncovers stress MAPK-associated sensitivity to AKT degradation

More than 50% of human tumors display hyperactivation of the serine/threonine kinase AKT. Despite evidence of clinical efficacy, the therapeutic window of the current generation of AKT inhibitors could be improved. Here, we report the development of a second-generation AKT degrader, INY-05-040, which outperformed catalytic AKT inhibition with respect to cellular suppression of AKT-dependent phenotypes in breast cancer cell lines. A growth inhibition screen with 288 cancer cell lines confirmed that INY-05-040 had a substantially higher potency than our first-generation AKT degrader (INY-03-041), with both compounds outperforming catalytic AKT inhibition by GDC-0068. Using multiomic profiling and causal network integration in breast cancer cells, we demonstrated that the enhanced efficacy of INY-05-040 was associated with sustained suppression of AKT signaling, which was followed by induction of the stress mitogen-activated protein kinase (MAPK) c-Jun N-terminal kinase (JNK). Further integration of growth inhibition assays with publicly available transcriptomic, proteomic, and reverse phase protein array (RPPA) measurements established low basal JNK signaling as a biomarker for breast cancer sensitivity to AKT degradation. Together, our study presents a framework for mapping the network-wide signaling effects of therapeutically relevant compounds and identifies INY-05-040 as a potent pharmacological suppressor of AKT signaling.

B7H3 increases ferroptosis resistance by inhibiting cholesterol metabolism in colorectal cancer

Ferroptosis, a newly discovered form of regulated cell death, has been reported to be associated with multiple cancers, including colorectal cancer (CRC). However, the underlying molecular mechanism is still unclear. In this study, we identified B7H3 as a potential regulator of ferroptosis resistance in CRC. B7H3 knockdown decreased but B7H3 overexpression increased the ferroptosis resistance of CRC cells, as evidenced by the expression of ferroptosis-associated genes (PTGS2, FTL, FTH, and GPX4) and the levels of important indicators of ferroptosis (malondialdehyde, iron load). Moreover, B7H3 promoted ferroptosis resistance by regulating sterol regulatory element binding protein 2 (SREBP2)-mediated cholesterol metabolism. Both exogenous cholesterol supplementation and treatment with the SREBP2 inhibitor betulin reversed the effect of B7H3 on ferroptosis in CRC cells. Furthermore, we verified that B7H3 downregulated SREBP2 expression by activating the AKT pathway. Additionally, multiplex immunohistochemistry was carried out to show the expression of B7H3, prostaglandin-endoperoxide synthase 2, and SREBP2 in CRC tumor tissues, which was associated with the prognosis of patients with CRC. In summary, our findings reveal a role for B7H3 in regulating ferroptosis by controlling cholesterol metabolism in CRC.

Insights into energy balance dysregulation from a mouse model of methylmalonic aciduria

Inherited disorders of mitochondrial metabolism, including isolated methylmalonic aciduria, present unique challenges to energetic homeostasis by disrupting energy-producing pathways. To better understand global responses to energy shortage, we investigated a hemizygous mouse model of methylmalonyl-CoA mutase (Mmut)-type methylmalonic aciduria. We found Mmut mutant mice to have reduced appetite, energy expenditure and body mass compared with littermate controls, along with a relative reduction in lean mass but increase in fat mass. Brown adipose tissue showed a process of whitening, in line with lower body surface temperature and lesser ability to cope with cold challenge. Mutant mice had dysregulated plasma glucose, delayed glucose clearance and a lesser ability to regulate energy sources when switching from the fed to fasted state, while liver investigations indicated metabolite accumulation and altered expression of peroxisome proliferator-activated receptor and Fgf21-controlled pathways. Together, these shed light on the mechanisms and adaptations behind energy imbalance in methylmalonic aciduria and provide insight into metabolic responses to chronic energy shortage, which may have important implications for disease understanding and patient management.

In vivo assignment of methylmalonic acid in breast tissue using 2D MRS and relationship with breast density, menopausal status and cancer risk

BACKGROUND

Methylmalonic acid (MMA) is linked to progression and aggressiveness of tumours. A recent study showed that high levels of circulatory MMA directed genetic programs promoting cancer progression.

PURPOSE

To evaluate in vivo two-dimensional correlated spectroscopy (2D COSY) data from women at elevated risk of breast cancer to determine if resonances consistent with MMA are present, and if so to correlate levels with breast density, menopausal status and risk categories.

MATERIALS AND METHODS

With institutional review board approval, 106 women at elevated risk (mean age 47), including 46 participants at medium risk, 43 at high risk with no known mutation and 17 BRCA-mutation carriers, were recruited. Breast density was assessed using a T₂ sequence. A T₁ sequence was used to place the voxel for the 2D COSY data. Peak volumes were normalized to the methylene peak at (1.30, 1.30) ppm. Chi-squared and Mann-Whitney tests were used.

RESULTS

Two resonances are assigned on the diagonal at 3.15 ppm and 3.19 ppm consistent with and denoted MMA1 and MMA2 respectively. MMA1 and MMA2 increased in parallel with increased risk. BRCA-mutation carriers recorded an increase in mean MMA1 of 120% (p = 0.033) and MMA2 of 127% (p = 0.020) in comparison with participants with no known mutation. BRCA-mutation carriers with dense breasts recorded a significant increase in mean MMA1 of 137% (p = 0.002) and in mean MMA2 of 143% (p = 0.004) compared with BRCA-mutation participants with low-density breast tissue. MMA1 and MMA2 were higher in premenopausal women with dense breasts compared with those with low-density tissue. The highest values of MMA were recorded in BRCA-mutation carriers.

CONCLUSION

Two tentative assignments are made for MMA in breast tissue of women at elevated risk for cancer. BRCA-mutation carriers exhibited higher values of MMA than those with no known mutation. Premenopausal women with BRCA mutation and dense breasts recorded the highest levels of MMA compared with other categories.

Macrophage-Derived 25-Hydroxycholesterol Promotes Vascular Inflammation, Atherogenesis, and Lesion Remodeling

BACKGROUND

Cross-talk between sterol metabolism and inflammatory pathways has been demonstrated to significantly affect the development of atherosclerosis. Cholesterol biosynthetic intermediates and derivatives are increasingly recognized as key immune regulators of macrophages in response to innate immune activation and lipid overloading. 25-Hydroxycholesterol (25-HC) is produced as an oxidation product of cholesterol by the enzyme cholesterol 25-hydroxylase (CH25H) and belongs to a family of bioactive cholesterol derivatives produced by cells in response to fluctuating cholesterol levels and immune activation. Despite the major role of 25-HC as a mediator of innate and adaptive immune responses, its contribution during the progression of atherosclerosis remains unclear.

METHODS

The levels of 25-HC were analyzed by liquid chromatography-mass spectrometry, and the expression of CH25H in different macrophage populations of human or mouse atherosclerotic plaques, respectively. The effect of CH25H on atherosclerosis progression was analyzed by bone marrow adoptive transfer of cells from wild-type or Ch25h-/- mice to lethally irradiated Ldlr-/- mice, followed by a Western diet feeding for 12 weeks. Lipidomic, transcriptomic analysis and effects on macrophage function and signaling were analyzed in vitro from lipid-loaded macrophage isolated from Ldlr-/- or Ch25h-/-;Ldlr-/- mice. The contribution of secreted 25-HC to fibrous cap formation was analyzed using a smooth muscle cell lineage-tracing mouse model, Myh11ERT2CREmT/mG;Ldlr-/-, adoptively transferred with wild-type or Ch25h-/- mice bone marrow followed by 12 weeks of Western diet feeding.

RESULTS

We found that 25-HC accumulated in human coronary atherosclerotic lesions and that macrophage-derived 25-HC accelerated atherosclerosis progression, promoting plaque instability through autocrine and paracrine actions. 25-HC amplified the inflammatory response of lipid-loaded macrophages and inhibited the migration of smooth muscle cells within the plaque. 25-HC intensified inflammatory responses of lipid-laden macrophages by modifying the pool of accessible cholesterol in the plasma membrane, which altered Toll-like receptor 4 signaling, promoted nuclear factor-κB-mediated proinflammatory gene expression, and increased apoptosis susceptibility. These effects were independent of 25-HC-mediated modulation of liver X receptor or SREBP (sterol regulatory element-binding protein) transcriptional activity.

CONCLUSIONS

Production of 25-HC by activated macrophages amplifies their inflammatory phenotype, thus promoting atherogenesis.

Microfluidic on-chip valve and pump for applications in immunoassays

On-chip valves can simplify a microfluidic chip and make it easy to operate. However, most on-chip valves already reported still need complicated manufacture and sophisticated supporting devices. In this work, we present a straightforward on-chip valve, which can be serially connected, to form an on-chip pump. The liquid can horizontally flow one way by the regular deformations of flexure strips in the two valves at both sides of the chamber under pressure changes in microchannels generated by repeated vertical movements of linear actuators. The volume of this system including the chip and the supporting device is 0.65 cubic decimeters, which is much smaller than that of reported systems with a volume of at least 12 cubic decimeters, and the weight of this system is only 0.56 kg, making it possible for point-of-care testing. We carry out an immunoassay of folic acid on chip, and the results show satisfactory reproducibility with acceptable coefficients of variation. We determine 163 clinical human serum samples for folic acid. Furthermore, we detect transferrin, cobalamin and folic acid simultaneously on one chip with both sandwich and competitive binding immunoassay methods. We anticipate that this on-chip valve and pump can be applied in immunoassays and other biosensing applications.

Impact of Non-Pharmacological Interventions on the Mechanisms of Atherosclerosis

Atherosclerosis remains the leading cause of mortality and morbidity worldwide characterized by the deposition of lipids and fibrous elements in the form of atheroma plaques in vascular areas which are hemodynamically overloaded. The global burden of atherosclerotic cardiovascular disease is steadily increasing and is considered the largest known non-infectious pandemic. The management of atherosclerotic cardiovascular disease is increasing the cost of health care worldwide, which is a concern for researchers and physicians and has caused them to strive to find effective long-term strategies to improve the efficiency of treatments by managing conventional risk factors. Primary prevention of atherosclerotic cardiovascular disease is the preferred method to reduce cardiovascular risk. Fasting, a Mediterranean diet, and caloric restriction can be considered useful clinical tools. The protective impact of physical exercise over the cardiovascular system has been studied in recent years with the intention of explaining the mechanisms involved; the increase in heat shock proteins, antioxidant enzymes and regulators of cardiac myocyte proliferation concentration seem to be the molecular and biochemical shifts that are involved. Developing new therapeutic strategies such as vagus nerve stimulation, either to prevent or slow the disease’s onset and progression, will surely have a profound effect on the lives of millions of people.

Association Between Methylmalonic Acid and Cognition: A Systematic Review and Meta-Analysis

BACKGROUND

Methylmalonic acid (MMA) is an intermediate metabolite of human body. The content of MMA in the blood of healthy people is very low, and its concentration will increase in some diseases and elderly people. Recent studies have shown that MMA has a variety of biological functions. The correlation between MMA and cognition, one of the important functions of the nervous system, is still uncertain.

OBJECTIVE

Meta-analyses were performed to assess whether elevated MMA was associated with the risk of cognitive decline.

MATERIALS AND METHODS

Cross-sectional studies, randomized controlled studies, and case-control studies on the relationship between MMA and cognition were obtained by searching PubMed, Web of Science, EMBASE, ProQuest, WANFANG MED ONLINE, China National Knowledge Infrastructure (CNKI) and Chongqing VIP until May 2022. Two researchers independently selected studies according to inclusion and exclusion criteria, evaluated study quality and extracted data. Meta-analyses were performed using Review Manager 5.4 software. The sensitivity analysis of meta-analysis was performed by One by one exclusion method.

RESULTS

A total of 11 studies were included, including six cross-sectional studies, two randomized controlled studies, and three case-control studies, with a sample of 16,533 subjects. Meta-analysis showed that there was no significant difference in cognitive level between high-level MMA subjects and low-level MMA subjects in the general population [SMD = -2.19, 95% CI (-4.76 ∼ 0.38), Z = 1.67, P = 0.09]. In the population supplemented with VitB12, the increase of MMA level caused by VitB12 supplementation was not related to the change of cognition [SMD = 0.32, 95% CI (-0.19 ∼ 0.84) z = 1.22, P = 0.22]. There was also no significant difference in MMA levels between patients with dementia and the control group [WMD = 20.89, 95% CI (-5.13 ∼ 46.92), z = 1.57, P = 0.12].

CONCLUSION

In the general population, whether VitB12 is supplemented or not, there is no correlation between the increase of MMA level and the decrease of cognitive level. In dementia diseases, the level of MMA did not change significantly. High levels of MMA may not be a risk factor for cognitive impairment. The exact relationship between MMA and cognition needs further research.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021266310], identifier [CRD42021266310].