The WWOX gene was initially discovered as a putative tumor suppressor. More recently, its association with multiple central nervous system (CNS) pathologies has been recognized. WWOX biallelic germline pathogenic variants have been implicated in spinocerebellar ataxia type 12 (SCAR12; MIM:614322) and in early infantile epileptic encephalopathy (EIEE28; MIM:616211). WWOX germline copy number variants have also been associated with autism spectrum disorder (ASD). All identified germline genomic variants lead to partial or complete loss of WWOX function. Importantly, large-scale genome-wide association studies have also identified WWOX as a risk gene for common neurodegenerative conditions such as Alzheimer’s disease (AD) and multiple sclerosis (MS). Thus, the spectrum of CNS disorders associated with WWOX is broad and heterogeneous, and there is little understanding of potential mechanisms at play. Exploration of gene expression databases indicates that WWOX expression is comparatively higher in the human cerebellar cortex than in other CNS structures. However, RNA in-situ hybridization data from the Allen Mouse Brain Atlas show that specific regions of the basolateral amygdala (BLA), the medial entorhinal cortex (EC), and deep layers of the isocortex can be singled out as brain regions with specific higher levels of Wwox expression. These observations are in close agreement with single-cell RNA-seq data which indicate that neurons from the medial entorhinal cortex, Layer 5 from the frontal cortex as well as GABAergic basket cells and granule cells from cerebellar cortex are the specific neuronal subtypes that display the highest Wwox expression levels. Importantly, the brain regions and cell types in which WWOX is most abundantly expressed, such as the EC and BLA, are intimately linked to pathologies and syndromic conditions in turn associated with this gene, such as epilepsy, intellectual disability, ASD, and AD. Higher Wwox expression in interneurons and granule cells from cerebellum points to a direct link to the described cerebellar ataxia in cases of WWOX loss of function. We now know that total or partial impairment of WWOX function results in a wide and heterogeneous variety of neurodegenerative conditions for which the specific molecular mechanisms remain to be deciphered. Nevertheless, these observations indicate an important functional role for WWOX in normal development and function of the CNS. Evidence also indicates that disruption of WWOX expression at the gene or protein level in CNS has significant deleterious consequences.

WWOX gene loss-of-function (LoF) has been associated with neuropathologies resulting in developmental, epileptic, and ataxic phenotypes of varying severity based on the level of WWOX dysfunction. WWOX gene biallelic germline variant p.Pro47Thr (P47T) has been causally associated with a new form of autosomal recessive cerebellar ataxia with epilepsy and intellectual disability (SCAR12, MIM:614322). This mutation affecting the WW1 protein binding domain of WWOX, impairs its interaction with canonical proline-proline-X-tyrosine motifs in partner proteins. We generated a mutant knock-in mouse model of Wwox P47T mutation that phenocopies human SCAR12. Wwox^P47T/P47T mice displayed epilepsy, profound social behavior and cognition deficits, and poor motor coordination, and unlike KO models that survive only for 1 month, live beyond 1 year of age. These deficits progressed with age and mice became practically immobile, suggesting severe cerebellar dysfunction. Wwox^P47T/P47T mice brains revealed signs of progressive neuroinflammation with elevated astro-microgliosis that increased with age. Cerebellar cortex displayed significantly reduced molecular and granular layer thickness and a strikingly reduced number of Purkinje cells with degenerated dendrites. Transcriptome profiling from various brain regions of WW domain LoF mice highlighted widespread changes in neuronal and glial pathways, enrichment of bioprocesses related to neuroinflammation, and severe cerebellar dysfunction. Our results show significant pathobiological effects and potential mechanisms through which WWOX partial LoF leads to epilepsy, cerebellar neurodegeneration, neuroinflammation, and ataxia. Additionally, the mouse model described here will be a useful tool to understand the role of WWOX in common neurodegenerative conditions in which this gene has been identified as a novel risk factor.

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Drug repurposing is the process of reusing existing pharmaceuticals for novel clinical purposes, which offers advantages such as streamlined clinical trial access and reduced drug development costs. Clarithromycin (CAM), a member of the macrolide antibiotics family, is a promising candidate for repurposing in cancer therapy due to its known preclinical and clinical immunomodulatory and anticancer properties. In the current study, we investigated whether CAM could be repurposed as a preventive treatment for KRAS-mutant lung cancer, a subtype of lung adenocarcinoma that is strongly associated with heavy smoking. CCSPCre; LSL-KrasG12D mice at an early stage of tumor development were treated with different doses of CAM for 10 weeks. While exhibiting an excellent safety profile, CAM was able to prevent the development of premalignant and malignant lung lesions in a dose-dependent manner. In addition, CAM significantly reduced the infiltration of neutrophils/polymorphonuclear myeloid-derived suppressor cells and inhibited the mRNA expression of protumor inflammatory cytokines IL-6, TNFα, and IL-1β, as well as M2 macrophage markers Fizz1 and Arginase1 in the lung tumor microenvironment. Moreover, we investigated the effect of CAM in reshaping the intestinal and lung microbiome. Long-term CAM usage decreased intestinal microbiome diversity but, more notably, significantly increased the abundance of the probiotic genus Muribaculaceae while decreasing the abundance of Desulfovibrio, a genus associated with the promotion of various malignancies. Taken together, we conclude that CAM could provide promising cancer prevention efficacy in KRAS-mutant lung cancer due to its immunomodulatory properties on the tumor microenvironment and its regulatory effects on the microbiome.

Supplementary figures and legends showing CAM effect on organ weight and blood chemistry analysis; survival study of CAM supplemented in chow diet; IHC staining of proliferation, apoptosis and angiogenesis; CAM treatment effect on lung microbiome.