The antimalarial drug mefloquine enhances TP53 premature termination codon readthrough by aminoglycoside G418

Abstract

Nonsense mutations constitute ~10% of TP53 mutations in cancer. They introduce a premature termination codon that gives rise to truncated p53 protein with impaired function. The aminoglycoside G418 can induce TP53 premature termination codon readthrough and thus increase cellular levels of full-length protein. Small molecule phthalimide derivatives that can enhance the readthrough activity of G418 have also been described. To determine whether readthrough enhancers exist among drugs that are already approved for use in humans, we tested seven antimalarial drugs for readthrough of the common R213X TP53 nonsense mutation in HDQ-P1 breast cancer cells. Mefloquine induced no TP53 readthrough activity as a single agent but it strongly potentiated readthrough by G418. The two enantiomers composing pharmaceutical mefloquine potentiated readthrough to similar levels in HDQ-P1 cells and also in SW900, NCI-H1688 and HCC1937 cancer cells with different TP53 nonsense mutations. Exposure to G418 and mefloquine increased p53 phosphorylation at Ser15 and P21 transcript levels following DNA damage, indicating p53 produced via readthrough was functional. Mefloquine does not appear to enhance readthrough via lysosomotropic effects as it did not significantly affect lysosomal pH, the cellular levels of G418 or its distribution in organellar or cytosolic fractions. The availability of a readthrough enhancer that is already approved for use in humans should facilitate study of the therapeutic potential of TP53 readthrough in preclinical cancer models.

Nsp1 of SARS-CoV-2 Stimulates Host Translation Termination

“…PTC readthrough stimulation and binding with the different parts of the 80S ribosome, especially with the ribosomal decoding center, were shown for gentamicin (Bidou et al, 2004; Prokhorova et al, 2017; Wilhelm et al, 1978). Binding to the ribosome GTPase-associated center of the Plasmodium falciparum 80S ribosome (Wong et al, 2017) and PTC readthrough promotion in the presence of G418 (Ferguson et al, 2019) were shown for mefloquine. Furthermore, debate on the possible use of mefloquine in the treatment of COVID19 did not stop.…”

“…As we have shown that Nsp1 can take part in translation termination by stimulating its first stage, stop codon recognition, antibiotics that induce PTC readthrough may be potentially useful in fighting the COVID infection. We tested in translation termination of two types of readthrough-inducing agents—the aminoglycoside antibiotic gentamicin and the antimalarial drug mefloquine (Bidou et al, 2004; Ferguson et al, 2019). We observed opposite effects of these substances at Nsp1-dependent stimulation of translation termination.…”

Small molecule Y-320 stimulates ribosome biogenesis, protein synthesis, and aminoglycoside-induced premature termination codon readthrough

“…It has recently been shown that PTC readthrough by aminoglycosides can be enhanced by small molecules that do not themselves stimulate readthrough when used as single agents [16][17][18][19]. We hypothesized that compounds might exist that overcome the self-limitation and increase PTC readthrough by G418 without further inhibiting protein synthesis.…”

Suppression of aminoglycoside-induced premature termination codon readthrough by the TRP channel inhibitor AC1903

“…Intracellular G418 was measured in cell lysates prepared for western analysis using an indirect competitive gentamicin ELISA kit (Creative Diagnostics, DEIA047, NY, USA), according to the manufacturer's protocol, as previously described (76). Standard curves were generated using G418 diluted in lysis buffer.…”