Command Palette

Search for a command to run...

Preprint WatchMildAugust 28th, 2026

Atypical MDM2 p53 Regulation and Chemosensitivity Induced by Proximal PAS Deletion

Kim M, Yoon C, Jun J, Lee Y, Chung H, Kim Y.

Deleting the proximal polyadenylation signal in the MDM2 three prime untranslated region lengthens the transcript, promotes nuclear retention through inverted Alu structures, lowers MDM2 protein and restores p53 activity with increased chemosensitivity.

Mild contradiction

1 prior failure

One documented clinical failure (Phase 1 or 2) overlaps with the claimed mechanism.

The preprint proposes reducing MDM2 protein by forcing distal polyadenylation rather than by occupying the p53 binding pocket, and reports lower MDM2 protein and increased chemosensitivity in an A549 model. Claidex holds one MDM2 failure, [[brigimadlin-mdm2-class-shutdown]], a sponsor decision that closed a small-molecule MDM2 inhibitor across MDM2-amplified TP53 wild-type tumours. The class problem for MDM2 inhibitors has been therapeutic index rather than target validity, so a route that lowers MDM2 output at the transcript level is a different lever on the same node. The flag is mild because the single matching failure was a portfolio decision rather than a negative efficacy readout, and because the preprint reports cell-line genome editing rather than a therapeutic modality.

Abstract excerpt

This study proposes a novel therapeutic strategy to suppress cancer growth by modulating the MDM2-p53 axis via Alternative Polyadenylation (APA). MDM2 normally promotes tumorigenesis by ubiquitinating and degrading the tumor suppressor p53. In cancer cells, preferential use of proximal polyadenylation signals (PAS) results in shortened 3′UTRs, allowing oncogenic transcripts like MDM2 to evade nuclear sequestration mediated by Inverted Alu (IRAlu) double-stranded RNA structures. We hypothesized that forcing distal PAS usage would elongate the MDM2 mRNA, promoting its nuclear retention and reducing protein translation, thereby restoring p53 activity. Using CRISPR-Cas9, we targeted and deleted the most frequent proximal PAS in the MDM2 3′UTR of A549 cells. Successful genome editing was confirmed via PCR. As expected, Western blot analysis showed a significant reduction in MDM2 expression in PAS-edited cells. However, experimental outcomes contradicted our initial hypothesis: edited cells exhibited higher viability under doxorubicin treatment compared to wild-type cells. Furthermore, despite decreased MDM2 levels, a concurrent reduction in phosphorylated p53 (p-p53) was observed. These unexpected results suggest that MDM2 3′UTR elongation may trigger a non-canonical regulatory mechanism that bypasses the traditional MDM2-p53 interaction. This study highlights the complexity of post-transcriptional regulation and suggests that APA-mediated gene modulation can induce unforeseen compensatory survival pathways in cancer cells, necessitating further investigation into the broader functional landscape of elongated 3′UTRs.

Matching Claidex post-mortems

1 of 1 indexed

This is an automated contradiction flag, not an editorial judgment on the preprint's quality. Flags identify where the preclinical literature and the clinical failure record diverge.