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The MYC oncogenic transcription factor is acetylated by the p300 and GCN5 histone acetyltransferases. The significance of MYC acetylation and the functions of specific acetylated lysine (AcK) residues have remained unclear. Here, we show that the major p300-acetylated K148(149) and K157(158) sites in human (or mouse) MYC and the main GCN5-acetylated K323 residue are reversibly acetylated in various malignant and nonmalignant cells. Oncogenic overexpression of MYC enhances its acetylation and alters the regulation of site-specific acetylation by proteasome and deacetylase inhibitors. Acetylation of MYC at different K residues differentially affects its stability in a cell type-dependent manner. Lysine-to-arginine substitutions indicate that although none of the AcK residues is required for MYC stimulation of adherent cell proliferation, individual AcK sites have gene-specific functions controlling select MYC-regulated processes in cell adhesion, contact inhibition, apoptosis, and/or metabolism and are required for the malignant cell transformation activity of MYC. Each AcK site is required for anchorage-independent growth of MYC-overexpressing cells in vitro, and both the AcK148(149) and AcK157(158) residues are also important for the tumorigenic activity of MYC transformed cells in vivo. The MYC AcK site-specific signaling pathways identified may offer new avenues for selective therapeutic targeting of MYC oncogenic activities.

Background This prospective observational study evaluated the real-world effectiveness of nivolumab monotherapy in previously treated advanced gastric cancer (GC). A preplanned 2-year final analysis was performed to confirm survival and tumor behavior with nivolumab monotherapy. Patients and Methods The primary endpoint was overall survival (OS). The data regarding tumor size were prospectively collected and evaluated using the RECIST criteria. Exploratory analyses were performed for survival according to the tumor response and depth of response (DpR) in patients with measurable lesions who were receiving nivolumab monotherapy as third- or later-line therapy. Results In 487 patients, the median OS and progression-free survival (PFS) were 5.8 (95% CI 5.3-6.9) months and 1.8 (95% CI 1.7-2.0) months, respectively. The response rate (RR) was 14.5% in 282 patients with measurable lesions. In 234 patients treated with third- or later-line, the DpR was found to be associated with PFS and OS in the Spearman analysis (r  = 0.55 and 0.44, respectively) as well as using a discrete variable. When the DpR was divided into 5 groups (−20%≥DpR; −20%

MYC is an oncogenic DNA-binding transcription activator of many genes and is often upregulated in human cancers. MYC has an N-terminal transcription activation domain (TAD) that is also required for cell transformation. Various MYC TAD-interacting coactivators have been identified, including the transcription/transformation-associated protein (TRRAP), a subunit of different histone acetyltransferase (HAT) complexes such as the human "SPT3-TAF9-GCN5 Acetyltransferase" (STAGA) complex involved in MYC transactivation of the TERT gene. However, it remains unclear whether TRRAP and/or other subunits are directly contacted by MYC within these macromolecular complexes. Here, we characterize the interactions of MYC TAD with the STAGA complex. By protein crosslinking we identify both TRRAP and the GCN5 acetyltransferase as MYC TAD-interacting subunits within native STAGA. We show that purified GCN5 binds to an N-terminal sub-domain of MYC TAD (residues 21-108) and that the interaction of GCN5 and STAGA with this sub-domain is dependent on two related sequence motifs: M2 within the conserved MYC homology box I (MBI), and M3 located between residues 100-106. Interestingly, specific substitutions within the M2/3 motifs that only moderately reduce the intracellular MYC-STAGA interaction and do not influence dimerization of MYC with its DNA-binding partner MAX, strongly inhibit MYC acetylation by GCN5 and reduce MYC binding and transactivation of the GCN5-dependent TERT promoter in vivo. Hence, we propose that MYC associates with STAGA through extended interactions of the TAD with both TRRAP and GCN5 and that the TAD-GCN5 interaction is important for MYC acetylation and MYC binding to certain chromatin loci.

For BRAF V600E-mutated metastatic colorectal cancer (mCRC), the BEACON phase 3 trial showed survival benefit of triplet therapy with cetuximab (anti-EGFR antibody), encorafenib (BRAF inhibitor) and binimetinib (MEK inhibitor) as well as doublet therapy with cetuximab and encorafenib over irinotecan-based chemotherapy plus anti-EGFR antibody. Both regimens are standards of care in Japan, but definite biomarkers for predicting efficacy and selecting treatment remain lacking. The mechanisms underlying resistance to these regimens also warrant urgent exploration to further evolve treatment. This prospective observational/translational study evaluated real-word clinical outcomes with cetuximab and encorafenib with or without binimetinib for BRAF-mutated mCRC patients and investigated biomarkers for response and resistance by collecting blood samples before and after treatment. Clinical Trial Registration:UMIN000045530 (https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000051983) The BEETS trial is a study that looks at how well two combinations of targeted therapies (cetuximab + encorafenib with or without binimetinib) work and how safe they are for patients with advanced colorectal cancer that has a mutation (change) in the BRAF gene. In this trial, patients participate voluntarily instead of being assigned to one of the two therapy groups. When a patient has BRAF-mutated advanced colorectal cancer, it means that the cancer cells in their body have changes in a gene called BRAF. This gene normally produces a protein called BRAF, which is involved in the growth of cells. However, when there is a mutation in this gene, it can cause the production of an overactive BRAF protein, leading to fast and excessive cell growth and division. For patients with BRAF-mutated advanced colorectal cancer, combinations of targeted therapies have been found to be effective as a second- or third-line treatment, based on the results of a phase 3 clinical trial. The main goal of the BEETS trial is to evaluate how well these treatments work and how safe they are when used in real-world clinical practice. Additionally, the study will use laboratory tests (liquid biopsy) to explore new biomarkers that can help predict how well a treatment will work and assist in selecting the most suitable treatment plans. We hope that the findings of this study will contribute to improving the overall management of this specific type of cancer. The protocol paper of the BEETS (JACCRO CC-18) trial, a prospective observational/translational study of BEACON regimens for BRAF-mutated mCRC, is now available in Future Oncology. [ABSTRACT FROM AUTHOR]