HMGB1 is a key architectural chromatin protein whose biological effects are highly context dependent. Recent findings reveal a distinct and cancer-specific role of the HMGB1 BoxA domain in regulating DNA integrity in lung cancer cells.
BoxA, the N-terminal DNA-binding domain of HMGB1, has previously been shown to introduce controlled DNA gaps in normal cells, relieving torsional stress and enhancing DNA stability. However, this protective mechanism does not translate to malignant cells. In lung cancer cell lines, overexpression of HMGB1 Box A leads to the formation of γH2AX foci, a hallmark of DNA double-strand breaks (DSBs), indicating that Box A acts as a pro-damage factor in the cancer genome.
DDR activation and selective genomic destabilization in Lung Cancer
At the molecular level, Box A–induced DNA breaks activate the DNA damage response (DDR) pathway. Increased γH2AX is accompanied by activation of the upstream kinases ATM and ATR, followed by modulation of p53 signaling.
This coordinated DDR activation reflects an inability of lung cancer cells to properly resolve Box A–induced DNA lesions, likely due to pre-existing defects in DNA repair pathways commonly observed in cancer.
Functionally, γH2AX-associated DSBs triggered by HMGB1 Box A result in:
- Suppression of lung cancer cell proliferation
- Reduced migratory capacity
- Enhanced apoptotic signaling
These outcomes highlight a fundamental contrast between normal and cancer cells, where the same HMGB1 domain promotes genome stabilization in healthy tissue but drives lethal genomic damage in lung cancer.
Collectively, these findings position HMGB1 Box A as a powerful molecular tool to selectively induce DNA damage in lung cancer and to probe vulnerabilities in DDR signaling pathways. This work also supports the broader concept of exploiting chromatin dynamics and HMGB1 biology for cancer-targeted therapeutic strategies.
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