Novel Correctors and Potentiators Enhance Translational Readthrough in CFTR Nonsense Mutations

by Selleckchem | Aug 10 2023

Premature-termination codons (PTCs) in CFTR (cystic fibrosis [CF] transmembrane conductance regulator) result in nonfunctional CFTR protein and are the proximate cause of ∼11% of CF-causing alleles, for which no treatments exist. The CFTR corrector lumacaftor and the potentiator ivacaftor improve CFTR function with terminal PTC mutations and enhance the effect of readthrough agents. Novel correctors GLPG2222 (corrector 1 [C1]), GLPG3221 (corrector 2 [C2]), and potentiator GLPG1837 compare favorably with lumacaftor and ivacaftor in vitro. Here, we evaluated the effect of correctors C1a and C2a (derivatives of C1 and C2) and GLPG1837 alone or in combination with the readthrough compound G418 on CFTR function using heterologous Fischer rat thyroid (FRT) cells, the genetically engineered human bronchial epithelial (HBE) 16HBE14o- cell lines, and primary human cells with PTC mutations. In FRT lines pretreated with G418, GLPG1837 elicited dose-dependent increases in CFTR activity that exceeded those from ivacaftor in FRT-W1282X and FRT-R1162X cells. A three-mechanism strategy consisting of G418, GLPG1837, and two correctors (C1a + C2a) yielded the greatest functional improvements in FRT and 16HBE14o- PTC variants, noting that correction and potentiation without readthrough was sufficient to stimulate CFTR activity for W1282X cells. GLPG1837 + C1a + C2a restored substantial function in G542X/F508del HBE cells and restored even more function for W1282X/F508del cells, largely because of the corrector/potentiator effect, with no additional benefit from G418. In G542X/R553X or R1162X/R1162X organoids, enhanced forskolin-induced swelling was observed with G418 + GLPG1837 + C1a + C2a, although GLPG1837 + C1a + C2a alone was sufficient to improve forskolin-induced swelling in W1282X/W1282X organoids. Combination of CFTR correctors, potentiators, and readthrough compounds augments the functional repair of CFTR nonsense mutations, indicating the potential for novel correctors and potentiators to restore function to truncated W1282X CFTR.

Comments:

The passage you provided discusses the evaluation of various compounds and their effects on CFTR (cystic fibrosis transmembrane conductance regulator) function in the context of premature-termination codons (PTCs) in CFTR. PTCs are genetic mutations that lead to nonfunctional CFTR protein and are responsible for approximately 11% of CF-causing alleles.

The compounds mentioned in the passage are:

1. Lumacaftor: A CFTR corrector that helps improve CFTR function in the presence of terminal PTC mutations.
2. Ivacaftor: A potentiator that enhances CFTR function.
3. GLPG2222 (corrector 1 [C1]) and GLPG3221 (corrector 2 [C2]): Novel CFTR correctors that compare favorably with lumacaftor in vitro.
4. GLPG1837: A potentiator that is evaluated alone or in combination with other compounds.
5. C1a and C2a: Derivatives of C1 and C2, respectively, evaluated as correctors.
6. G418: A readthrough compound that promotes the readthrough of premature stop codons during protein translation.

The evaluation of these compounds was conducted using different cell lines and primary human cells with PTC mutations. The results showed that GLPG1837, especially in combination with G418, elicited dose-dependent increases in CFTR activity, surpassing the effect of ivacaftor in specific cell lines with PTC mutations. The combination of G418, GLPG1837, and two correctors (C1a + C2a) yielded the greatest functional improvements in various cell lines.

Additionally, the study found that GLPG1837 + C1a + C2a alone could restore significant CFTR function in certain PTC variants, such as G542X/F508del and W1282X/F508del cells. In organoids derived from patients with specific CFTR mutations, the combination of G418, GLPG1837, C1a, and C2a enhanced forskolin-induced swelling, indicating improved CFTR function.

Overall, the findings suggest that a combination of CFTR correctors, potentiators, and readthrough compounds may enhance the functional repair of CFTR nonsense mutations. This highlights the potential of novel correctors and potentiators in restoring CFTR function, particularly in the case of the W1282X CFTR mutation.