OXCT1-Targeting SAMe Suppresses Cerebral Cavernous Malformation Progression in Mice
Cerebral Cavernous Malformations and Mitochondrial Abnormalities
S-adenosylmethionine (SAMe) was reported to suppress disease progression in a mouse model of cerebral cavernous malformations (CCM). The researchers proposed 3-oxoacid CoA-transferase 1 (OXCT1), which is involved in mitochondrial function, as a therapeutic target. However, the available abstract alone does not establish that SAMe worked by inhibiting this enzyme.
CCM lesions consist of clusters of thin-walled blood vessels with slow blood flow in the central nervous system and can cause stroke. They can also arise from PDCD10 deficiency, and experimental evidence has accumulated implicating mitochondrial dysfunction in disease development. The specific mechanisms that disrupt mitochondrial balance remain unclear.
Distinguishing OXCT1 Loss of Function from SAMe’s Effects
The researchers used RNA sequencing (RNA-seq) data from PDCD10-deficient endothelial cell lines generated with CRISPR/Cas9 gene editing, primary endothelial cells from Pdcd10 BECKO mice, and endothelial cells derived from patients with CCM. They identified OXCT1 as a central gene involved in mitochondrial pathways during CCM progression. The study used patient-derived cells; these are not results from a clinical trial in which patients received the drug.
OXCT1 is located in the mitochondrial matrix and is involved in ketone-body metabolism and several mitochondrial functions. Loss-of-function variants in OXCT1 in malformed vascular endothelium promoted disease progression and mediated mitochondrial damage. These findings therefore cannot be interpreted as evidence that inhibiting OXCT1 alleviates the disease.
Through large-scale virtual screening, the researchers identified SAMe, a methyl donor, as a small-molecule candidate targeting the OXCT1 active site. They then reported that SAMe suppressed disease progression in a mouse CCM model. The abstract alone does not establish in which direction SAMe changes OXCT1 enzyme activity or how that change relates to the suppression of disease progression.
What Remains to Be Validated for a Therapeutic Candidate
This study links OXCT1 to mitochondrial abnormalities in CCM and provides preclinical grounds for further evaluation of SAMe. It is too early to conclude that SAMe normalized both ketone-body metabolism and mitochondrial function.
The researchers mentioned the potential for oral administration of SAMe, its high bioavailability, and its favorable safety characteristics. However, the available abstract does not provide the dose, treatment duration, sample size, comparator groups, effect size, or specific safety assessment results. The findings do not establish efficacy or safety for treating CCM in people. Interpretation is limited to suppression of progression in the mouse model and the findings from cell studies.
Source: Bibliographic information and abstract for the paper published in International Journal of Biological Macromolecules.
Cerebral cavernous malformations (CCMs) are low-flow, thin-walled vascular conglomerates that arise within the central nervous system and constitute a significant cause of stroke. Experimental evidence indicates that mitochondrial dysfunction contributes to the pathogenesis of CCM, a disease that can be caused by PDCD10 deficiency. However, the specific mechanisms underlying mitochondrial homeostatic imbalance remain unclear. 3-oxoacid CoA-transferase 1 (OXCT1), localized in the mitochondrial matrix, serves as the rate-limiting enzyme of ketone body metabolism. Additionally, it also modulates diverse mitochondrial functions. Although the function of OXCT1 has been implicated in various diseases, its role in the progression of CCM awaits elucidation. Utilizing RNA-seq data from the CRISPR/Cas9-generated PDCD10-knockout endothelial cell line, primary endothelial cells from Pdcd10
The practical significance of this study is that it proposes OXCT1 as a target for investigating metabolic and mitochondrial abnormalities in cerebral cavernous malformations and provides a basis for further preclinical evaluation of SAMe. For example, follow-up studies could measure OXCT1 activity and mitochondrial markers before and after SAMe treatment, then test whether those changes are linked to suppression of disease progression in mice. Given that OXCT1 loss of function worsened disease, it is essential to distinguish evidence that a compound acts on the target from a claim that it inhibits the enzyme. Before this approach could lead to treatment for patients, dosing conditions, reproducibility of the effects, and efficacy and safety in people with CCM would need to be assessed separately.