The HDAC inhibitor SAHA does not rescue CFTR membrane expression in Cystic Fibrosis

Abstract

The development of suitable Cystic Fibrosis (CF) models for preclinical bench tests of therapeutic candidates is challenging. Indeed, the validation of molecules to rescue the p.Phe508del-CFTR channel (encoded by the Cystic Fibrosis Transmembrane conductance Regulator gene carrying the p.Phe508del mutation) requires taking into account their overall effects on the epithelium. Suberoylanilide Hydroxamic Acid (SAHA), a histone deacetylase inhibitor (HDACi), was previously shown to be a CFTR corrector via proteostasis modulation in CFTR-deficient immortalized cells. Here, we tested SAHA effects on goblet cell metaplasia using an ex vivo model based on the air-liquid interface (ALI) culture of differentiated airway epithelial cells obtained by nasal scraping from CF patients and healthy controls. Ex vivo epithelium grew successfully in ALI cultures with significant rise in the expression of CFTR and of markers of airway epithelial differentiation compared to monolayer cell culture. SAHA decreased CFTR transcript and protein levels in CF and non-CF epithelia. Whereas SAHA induced lysine hyperacetylation, it did not change histone modifications at the CFTR promoter. SAHA reduced MUC5AC and MUC5B expression and inhibited goblet epithelial cell differentiation. Similar effects were obtained in CF and non-CF epithelia. All the effects were fully reversible within five days from SAHA withdrawal. We conclude that, ex vivo, SAHA modulate the structure of airway epithelia without specific effect on CFTR gene and protein suggesting that HDACi cannot be useful for CF treatment.

Inhibition of histone-deacetylase activity rescues inflammatory cystic fibrosis lung disease by modulating innate and adaptive immune responses

“…5c ). Although, a single recent study suggests that SAHA may not significantly rescue membrane CFTR levels but data from this study is inconclusive due to insuffiecient number of replicates and experimental variation, where SAHA mediated CFTR increase was observed in some cellular models but not other [ 43 ]. Moreover, the same study also suggests that SAHA treatment decreases CFTR mRNA levels and thus cannot be used as an efficient CFTR corrector.…”

HDAC inhibitors rescue multiple disease-causing CFTR variants

“…Vorinostat, belinostat, panobinostat and romidepsin are four HDACi approved by the US Food and Drug Administration (FDA) to treat cutaneous and peripheral T-cell lymphoma (75,(77)(78)(79). Vorinostat appears to abrogate the phenotypic defects associated with the F508del variant by modulating immune responses (80,81) and improving the stability and trafficking of F508del-CFTR (74,82). While a recent manuscript has reported conflicting data pertaining to the impact of Vorinostat on the F508del variant of CFTR in nasal epithelial cells, the results likely reflect expected cell-specific environments that are differentially sensitive to epigenetic alterations (82).…”

HDAC Inhibitors Rescue Multiple Disease-Causing CFTR Variants

“…While CFBE410-cells are a commonly used cellular model to study the folding, trafficking and function of CFTR variants and have proven useful in the identification of small molecule therapeutics and targets to treat CFTR phenotypic defects, they express CFTR from a transgene driven by a viral promoter, which fails to recapitulate CFTR biology and its endogenous promoter activity that are likely to have tissue specific responses triggering variable levels of expression and/or the maladaptive stress response (MSR) that is known to contribute to the etiology of disease and its corrective potential through proteostasis modulation [101]. Consistent with this view, a recent report indicated that Vorinostat cannot correct nasal epithelial cell conductance when placed in transwell culture, conditions which recapitulate the nasal respiratory environment [89].…”

“…Vorinostat appears to abrogate the phenotypic defects associated with the F508del variant by modulating immune responses [87,88] and improving the stability and trafficking of F508del-CFTR [89,90]. While a recent manuscript has reported conflicting data pertaining to the impact of Vorinostat on the F508del variant of CFTR in nasal epithelial cells, the results likely reflect expected cell-specific environments that are differentially sensitive to epigenetic alterations [89].…”

“…Despite conflicting results for CF, likely reflecting the multiple cell-specific environments contributing CF etiology that are differentially sensitive to the epigenetic program, Vorinostat appears to abrogate the phenotypic defects associated with the F508del variant of CFTR by modulation of innate and adaptive immune responses [87,88] as well as by improving the stability and trafficking of F508del CFTR [89,90], albeit a recent manuscript has reported conflicting data pertaining to the impact of Vorinostat on the F508del variant of CFTR in nasal epithelial cells, likely reflecting their unique genomic/epigenomic environment when measured in culture [89]. Given the low and variable response for all CFTR classes to known corrector/potentiator therapeutics, an urgent need exists for general modifiers of drug responses that level the playing field for a given variant within the population.…”