The oncoprotein BCL6 enables solid tumor cells to evade genotoxic stress

Abstract

Genotoxic agents remain the mainstay of cancer treatment. Unfortunately, the clinical benefits are often countered by a rapid tumor adaptive response. Here, we report that the oncoprotein B cell lymphoma 6 (BCL6) is a core component that confers solid tumor adaptive resistance to genotoxic stress. Multiple genotoxic agents promoted BCL6 transactivation, which was positively correlated with a weakened therapeutic efficacy and a worse clinical outcome. Mechanistically, we discovered that treatment with the genotoxic agent etoposide led to the transcriptional reprogramming of multiple pro-inflammatory cytokines, among which the interferon-α and interferon-γ responses were substantially enriched in resistant cells. Our results further revealed that the activation of interferon/signal transducer and activator of transcription 1 axis directly upregulated BCL6 expression. The increased expression of BCL6 further repressed the tumor suppressor PTEN and consequently enabled resistant cancer cell survival. Accordingly, targeted inhibition of BCL6 remarkably enhanced etoposide-triggered DNA damage and apoptosis both in vitro and in vivo. Our findings highlight the importance of BCL6 signaling in conquering solid tumor tolerance to genotoxic stress, further establishing a rationale for a combined approach with genotoxic agents and BCL6-targeted therapy.

B cell lymphoma 6 promotes hepatocellular carcinoma progression by inhibiting tumor infiltrating CD4+T cell cytotoxicity through ESM1

“…BCL6 was reported to act as proto-oncogene by affecting cancer hallmark pathways including proliferation, DNA repair, anti-apoptosis, and enable cancer cells to adapt to stress 25 . As a highly conserved protein, BCL6 play nonredundant role in immune modulation.…”

Differential Spatial Gene and Protein Expression Associated with Recurrence Following Chemoradiation for Localized Anal Squamous Cell Cancer

“…We also observed the higher expression of biomarkers associated with radioresistance in pretreatment specimens of the TME of patients with recurrent anal cancer. Specifically, higher phospho-Akt expression (associated with PI3K/mTOR signaling activation and radioresistance) [ 35 , 36 , 37 ], higher BCL-6 (associated with anti-apoptotic activity in response to DNA damage-induced stress) [ 38 , 39 ] and higher phospho-GSKβ (associated with the activation of oncogenic Wnt/β-catenin, MAPK, PI3K/mTOR and Notch signaling activity) [ 40 , 41 ] were measured at higher levels in this cohort relative to their counterparts who were eventually cured by chemoradiation. Based on these findings, it is possible that tumors in the prognostically unfavorable anal cancer group who recurred were predisposed to overcome induced stress on the DNA by both cytotoxic chemotherapy and radiotherapy in order to account for the inability to achieve a curative outcome by multimodality treatment.…”

BCL6 is regulated by the MAPK/ELK1 axis and promotes KRAS-driven lung cancer

“…Moreover, the combined inhibition of BCL6 and STAT3 synergistically defeats intratumoral heterogeneity in a subset of non–small cell lung cancers ( 20 ). We recently revealed that BCL6 enables solid tumor cells to evade genotoxic stress ( 21 ), and pharmacological inhibition of BCL6 enhances the sensitivity of KRAS -mutant lung cancer cells to clinical BETi ( 22 ). However, the biological function of BCL6 in KRAS -mutant lung tumorigenesis remains unclear.…”