A stress-dependent TRIM28-ALKBH2 feedback loop modulates chemotherapy response

Chemoresistance to DNA-damaging agents, including platinum and alkylating compounds, limits treatment efficacy in non-small cell lung cancer (NSCLC) and is frequently associated with elevated DNA repair activity. Here, we identify a stress-responsive feedback loop between the E3 ligase TRIM28 and the demethylase ALKBH2. TRIM28 directly binds ALKBH2 and mediates its K48-linked polyubiquitination and proteasomal degradation, whereas ALKBH2 enhances TRIM28 transcription, forming a reciprocal loop that regulates their steady-state levels. Alkylation stress triggers a biphasic response: acute MMS exposure increases TRIM28-ALKBH2 complex formation, further augmented by MAGEA6, and accelerates ALKBH2 degradation, whereas prolonged MMS treatment induces K48-linked ubiquitination and proteasomal degradation of TRIM28, leading to ALKBH2 stabilization and increased ALKBH2 transcription. Clinically, ALKBH2 is elevated in lung adenocarcinoma and correlates with poorer survival, whereas TRIM28 shows prognostic association only in chemotherapy-treated patients. Functionally, combining MMS with cisplatin increases DNA damage, reduces clonogenic survival, and attenuates ALKBH2-dependent tolerance to alkylation damage, linking the TRIM28-ALKBH2 axis to chemotherapy response in NSCLC. Together, these results identify a stress-responsive biphasic TRIM28-ALKBH2 regulatory loop that coordinates ubiquitin-dependent and transcription-linked mechanisms to shape alkylation responses and modulate chemotherapy sensitivity in NSCLC.