bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.02.09.577647

The RNA demethylases ALKBH5 and FTO regulate translation of the ATF4 mRNA in sorafenib-treated hepatocarcinoma cells

Mazroui, R.·Adjibade, P.
View original source ↗Export metadata ↓

Abstract

Translation is one of the main gene expression steps targeted by cellular stress, commonly refereed as translational stress, which includes treatment with anticancer drugs. While translational stress blocks translation initiation of bulk mRNAs, it allows translation of a specific set of mRNAs known as short upstream open reading frames (uORFs)-mRNAs. Among these, ATF4 mRNA encodes a transcription factor that reprograms gene expression during various cellular stress towards functions required for cell response to stress. Stress-induced ATF4 mRNA translation occurs via a specialised mode that relies on the presence of uORFs upstream to the main ATF4 ORF. However, mechanisms regulating ATF4 mRNA translation, particularly towards chemoresistance, remained limited. Here, we report a role of both ALKBH5 and FTO, the two RNA demethylating enzymes in promoting translation of ATF4 mRNA in liver cancer Hep3B cells treated with sorafenib, a stress inducer used in chemotherapy. Depletion experiments confirmed that both enzymes are required for inducing ATF4 mRNA translation, while polyribosome assays coupled to RT-qPCR indicated that this induction of ATF4 mRNA translation occurs at its initiation step. Using in vitro methylation assays, we found that ALKBH5 is required for the inhibition of the methylation of a reporter ATF4 mRNA at a conserved adenosine (A235) site located at its uORF2, suggesting that ALKBH5-mediated translation of ATF4 mRNA involves demethylation of its A235. Preventing methylation of A235 by introducing an A/G mutation into the ATF4 mRNA reporter renders that reporter insensitive to ALKBH5 depletion, supporting the role of ALKBH5 demethylation activity in translation. Finally, targeting either ALKBH5 or FTO sensitizes Hep3B to sorafenib-induced cell death, contributing to their resistance. We concluded that ALKBH5 and FTO are novel factors that promote resistance to sorafenib treatment, in part by mediating translation of ATF4 mRNA.

Explore related subjects

cancer biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Mazroui, R., Adjibade, P.. 2024-02-12. The RNA demethylases ALKBH5 and FTO regulate translation of the ATF4 mRNA in sorafenib-treated hepatocarcinoma cells. https://doi.org/10.1101/2024.02.09.577647

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Epigenetic progression of pancreatic cancer to aggressive subtypes involves alternate routes of lineage reprogramming in subtype-intermediate progenitor cells

Pancreatic ductal adenocarcinoma (PDAC) progression involves malignant cell state plasticity. Epigenetic changes underlie this plasticity, yet the PDAC cis-regulatory landscape remains understudied. To address this, we profiled 33 primary tumors and 7 metastases from 39 patients with single-cell ATAC-seq, paired with 10 single-cell RNA-seq profiles. We found that epigenetic GATA6+/KRT17+ co-accessibility identifies a classical-basal subtype-intermediate progenitor state (SIP) associated with better clinical outcomes. SIP cells display limited epigenetic reprogramming from premalignant epithelium and retain gastric-intestinal differentiation reminiscent of neoplastic precursors. Lineages without GATA6+/KRT17+ co-accessibility exhibit greater lineage and epithelial-mesenchymal plasticity. Classical PDACs that repress basal gene accessibility activate neural-like progenitor (NRP) and tuft lineage enhancers, whereas basal committed tumors display esophageal transdifferentiation. Compared to SIP, classical-NRP and basal committed tumors have poorer outcomes, and show distinct PD-1/PD-L1 immune proteomic phenotypes and prognostic myofibroblast epigenetic states, respectively. Our work reveals links between lineage reprogramming, EMT, and epigenetic progression in human PDAC.

cancer biology↗
bioRxiv2026

Tissue resident CD4+ memory T-cells mark response to immune checkpoint inhibition in high-grade glioma

Background: Immune checkpoint inhibitors (ICI) are efficacious in many solid tumors, but response in glioma is restricted to a small subgroup. The determinants of response and resistance to ICI remain poorly understood. Methods: Here we exploit a syngeneic hypermutated high-grade glioma model with dichotomous response to combined PD-1 and CTLA-4 inhibition to unravel determinants of tumor-infiltrating T-cells driving response. Tumor-infiltrating T-cells from ICI-responsive and non-responsive tumors were analyzed by single-cell RNA and T-cell receptor sequencing and tumor-reactive T-cell receptor clonotypes were functionally validated to characterize their transcriptional phenotypes. We verify our findings in IDH1 wildtype glioblastoma patients treated with neoadjuvant pembrolizumab. Results: ICI response was associated with intratumoral clonal expansion of tumor-reactive cytotoxic T-cells and increased infiltration of CXCR6+ CD4+ tissue resident memory T-cells (Trm). CD4 stem-like memory T-cells in responding tumors demonstrated elevated interferon responses, following trajectories toward clonally expanded Trm, versus trajectories toward exhaustion in non-responsive tumors. In responsive tumors, CD4+ Trm interacted with infiltrating CXCR3+ tumor-reactive and clonally expanded, yet transcriptionally versatile cytotoxic T-cells. Probing the post neoadjuvant ICI high-grade glioma patient tissue dataset, we confirmed increased CXCR6 expression in CD4+ T cells and the association of CD4+ Trm with prolonged overall survival. Conclusion: These findings identify CD4 tissue-resident memory T-cells as determinants of ICI response in IDH1 wildtype high-grade glioma and warrant their further investigation to improve immunotherapy outcomes.

cancer biology↗
bioRxiv2026

Low-dose doxorubicin drives caveolin-1 depended re-epithelialization of breast cancer cells as a mechanism of cancer plasticity

Breast cancer progression is driven by dynamic changes in epithelial plasticity, membrane organization, and intracellular signaling, yet the effects of sustained low-dose chemotherapy on these processes remain poorly understood. Here, we investigated the impact of prolonged low-dose doxorubicin on membrane remodeling, epithelial phenotype, membrane-associated Ras lipid-anchor localization, and autophagy in mesenchymal-like MDA-MB-231 breast cancer cells. Low-dose doxorubicin significantly increased Caveolin-1 expression and enhanced E-cadherin protein levels, accompanied by a transition toward a more compact epithelial-like morphology with increased cell-cell contacts. Live-cell imaging demonstrated a significant reduction in the membrane-to-cytoplasm fluorescence ratio of the lipid-anchored GFP-tH probe, indicating redistribution from the plasma membrane to the cytoplasm following treatment. Analysis of autophagy-related proteins revealed decreased LC3-I together with increased LC3-II, ATG5, and p62 expression, consistent with autophagosome accumulation and impaired autophagic flux. Collectively, our findings demonstrate that low-dose doxorubicin promotes extensive remodeling of plasma membrane organization, epithelial plasticity, membrane-associated lipid-anchor localization, and autophagy. This integrated response reveals previously unrecognized links between membrane architecture, Ras membrane association, and autophagy during phenotypic reprogramming of breast cancer cells, providing mechanistic insight into cellular adaptations elicited by sub-cytotoxic doxorubicin exposure.

cancer biology↗