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Tumorigenesis and chemotherapy resistance are all related to it?
Written by | Small rocks on top of the mountain
In recent years, the study of the mechanism of lactation modification in tumor cell metabolomics has gradually become a hot topic, and with the deepening of researchers' understanding and awareness of lactation modification and DNA damage repair, the latest progress has been made in the exploration of lactate in tumor cell development and therapeutic resistance mechanism. Recently, the journal Cell has provided a comprehensive report on this progress, providing potential targets and treatment options for future cancer treatments.
AARS1 promotes tumorigenesis by lactating P53
On April 22, 2024, the latest findings of Professor Zhou Fangfang's team at Soochow University were published in the journal Cell: tumor-derived lactate acts as a natural inhibitor of p53, and alayl tRNA synthetase (AARS1) can catalyze global lysine lactation through direct binding, inducing impaired DNA binding and decreased transcriptional activity, and ultimately promoting tumorigenesis.
By evaluating the TCGA breast cancer dataset, the investigators found that in wild-type p53 patients, those with higher serum lactate levels had significantly lower p53 signaling pathway scores, suggesting that lactate in the tumor may inhibit the function of p53. In the mouse model of transgenic breast cancer, the lactate level of the tumor gradually increased with the progression of the tumor and was positively correlated with the tumor burden, suggesting that the accumulation of lactate in the cells may accelerate the progression of the tumor. In addition, the delay in tumor formation, the reduction of tumor lactate and tumor burden, and the increase of p53 activity were observed after lactate dehydrogenase (LDHA) knockout in model mice.
In order to identify the key proteins that mediate the lactation of tumor-derived p53, the researchers screened AARS1 with the strongest correlation through genome-wide CRISPR screening. As a member of the aminoacyl tRNA synthetase (ARS) family, AARS1 catalyzes the attachment of alanine to tRNA (Ala) during protein translation. AARS1 depletion increases the expression of the p53 target gene, desensitizing it to lactate-induced inhibition responses, resulting in a significant reduction in tumor cell proliferation, colony formation, and xenograft tumor growth.
In the proteomic analysis of lactate-modified proteins, when AARS1 is briefly depleted, the intensity of about 80% of Kla-modified peptides and proteins is significantly reduced, and the intensity of 10% of peptides and proteins is reduced by more than 10-fold. In contrast, 90% of the lactated peptides and proteins were significantly increased in AARS1-overexpressing tumor cells, with nearly 50% of them enhanced by more than 10-fold. These results suggest that AARS1 is a key mediator of global lysine lactation in cells.
In order to clarify the mechanism of AARS1-mediated lactation, the researchers conducted a series of in vitro biochemical experiments, and the final results showed that AARS1 directly binds to lactate to form the intermediate product lactate-AMP, which covalently binds to the lysine receptor end and releases AMP to mediate the lactation process.
Mass spectrometry analysis of cells transfected with AARS1 and treated with sodium lactate revealed that K120 and K139 were lactated binding sites on p53. In order to clarify the molecular mechanism of the regulation of lactation activity on the p53 DNA binding domain (DBD), the researchers conducted further cell and animal experiments after the construction of site-specific p53 lactation mutants. The results showed that DNA binding was impaired, liquid-liquid phase separation (LLPS) was weakened, and transcriptional activity was reduced in the mutants, especially in mice in tumor models, which eventually led to the occurrence of tumors. These findings are also supported by measurements of patient-derived tissue samples. By competitively binding β-alanine with AARS1, it can effectively control p53 inactivation and improve the effect of chemotherapy, which provides a very promising research direction for synergistic effects in tumor treatment.
Metabolic regulation of MRE11 lactation on homologous recombination repair
Coincidentally, prior to this, Professor Yuan Jian's team from Tongji University also published a study entitled "Metabolic regulation of homologous recombination repair by MRE11 lactylation" in Cell, which elucidated the molecular biological mechanism of MRE11, a key protein in DNA damage repair, which promotes homologous recombination repair (HR) through lactation modification, and ultimately leads to chemotherapy resistance. It also provides new therapeutic targets and directions for the intervention of chemotherapy resistance.
Among the main results of this study, the specific mechanism of action of lactation is as follows:
1. Promote DNA damage repair and chemotherapy resistance
LDHA is the main enzyme that mediates lactate production in the body, and lactate production can further promote the lactation of proteins, and patients with low LDHA expression levels tend to show higher HRD scores. In order to clarify the role of high levels of lactate or protein lactation in HR repair, HR reporter analysis was performed after treating cells with sodium lactate, and the observation showed that pantolactation of cells and HR repair were enhanced, and DNA damage repair was also promoted. All of these results were suppressed with LDH inhibitors. Cancer cell experiments have observed resistance to cisplatin or olaparib treatment.
2CBP is lactated by MRE11 K673
In the above experiments, the researchers observed the high lactation of MRE11, and confirmed that CBP mediated the lactation of MRE11 through the K673 site of the second DBD through in vitro lactation experiments and mass spectrometry, and that it was significantly enhanced in the presence of DNA damage.
3MRE11 lactation can improve DNA binding capacity and enhance end excision
In order to explore whether lactation affects the binding of MRE11 DNA, after in vitro lactation assay and in vitro DNA binding assay using purified MRE11 WT, the researchers found that MRE11 lactation could promote its binding to dsDNA and overhang DNA, and NALA treatment enhanced the formation of MRE11 and MRE11-K673la lesions and MRE11 chromatin load. Inhibition or depletion of CBP or LDHi treatment reduces the formation of MRE11 lesions and the recruitment of chromatin.
Further phospho-RPA2 and 5-BrdU foci showed that both LDHi treatment and LDHA/B depletion could significantly reduce cisplatin-induced phosphorylated RPA2 levels, and NALA treatment could save the impaired phosphorylated RPA2 levels after LDHA/B or LDHi treatment. In addition, the overexpression of CBP in control cells can significantly increase the level of phosphorylated RPA2. These findings suggest that lactation may regulate DNA end excision through the CBP-MRE11 axis.
4. Peptide inhibitors targeting MRE11 K673 lactation can improve chemotherapy sensitivity
The specific peptide inhibitor K673-pe showed a significant inhibitory effect on MRE11 K673, and significantly reduced the end excision of DNA and the number of RAD51 lesions. Further observation showed that K673-pe could significantly enhance the sensitivity of tumor cells to cisplatin and olaparib, providing a potential treatment option for enhancing the chemotherapy effect of MRE11 K673 lactated high-level tumors.
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With the accumulation of more experimental data, cancer prevention and treatment will continue to move forward in the direction of personalization and precision.
Resources:
[1] Zong et al., Alanyl-tRNA synthetase, AARS1, is a lactate sensor and lactyltransferase that lactylates p53 and contributes to tumorigenesis, Cell (2024), https://doi.org/10.1016/j.cell.2024.04.002
[2] Chen Y, Wu J, Zhai L, Zhang T, Yin H, Gao H, Zhao F, Wang Z, Yang X, Jin M, Huang B, Ding X, Li R, Yang J, He Y, Wang Q, Wang W, Kloeber JA, Li Y, Hao B, Zhang Y, Wang J, Tan M, Li K, Wang P, Lou Z, Yuan J. Metabolic regulation of homologous recombination repair by MRE11 lactylation. Cell. 2024 Jan 18; 187(2):294-311.e21. doi: 10.1016/j.cell.2023.11.022.
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