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Enhancer of zeste homolog 2 (EZH2) is a key epigenetic regulator that catalyzes the trimethylation of H3K27 and is modulated by post-translational modifications (PTMs). However, the precise regulation of EZH2 PTMs remains elusive. We, herein, report that EZH2 is acetylated by acetyltransferase P300/CBP-associated factor (PCAF) and is deacetylated by deacetylase SIRT1. We identified that PCAF interacts with and acetylates EZH2 mainly at lysine 348 (K348). Mechanistically, K348 acetylation decreases EZH2 phosphorylation at T345 and T487 and increases EZH2 stability without disrupting the formation of polycomb repressive complex 2 (PRC2). Functionally, EZH2 K348 acetylation enhances its capacity in suppression of the target genes and promotes lung cancer cell migration and invasion. Further, elevated EZH2 K348 acetylation in lung adenocarcinoma patients predicts a poor prognosis. Our findings define a new mechanism underlying EZH2 modulation by linking EZH2 acetylation to its phosphorylation that stabilizes EZH2 and promotes lung adenocarcinoma progression.

HOXB9 is a homeobox domain-containing transcription factor, playing an important role in embryonic development and cancer progression. However, the precise post-translational modifications (PTMs) of HOXB9 and the corresponding roles are unclear. Here, we report that acetyltransferase p300/CBP-associated factor (PCAF) interacts with and acetylates HOXB9 both in vivo and in vitro. Conversely, the acetylation of HOXB9 can be reversed by deacetylase SIRT1. Furthermore, we found that HOXB9 is acetylated at lysine 27 (AcK27). Functionally, in contrast to the wild type HOXB9, AcK27-HOXB9 decreased its capacity in promoting lung cancer cell migration and tumor growth in mice. Mechanistically, AcK27-HOXB9 suppresses the transcription of its target gene Jumonji domain-containing protein 6 (JMJD6) by direct occupying the promoter of JMJD6 gene. For clinical relevance, elevated HOXB9 acetylation at K27 predicts a better prognosis in lung adenocarcinoma patients. Taken together, we identified the first PTM of HOXB9 by demonstrating that HOXB9 can be acetylated and AcK27-HOXB9 counteracts the role of the wild-type HOXB9 in regulating lung adenocarcinoma progression.

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Edited by Dietmar J. Manstein Keywords:Kindlin-2 a-Actinin-2The Z-disc Cardiac structure a b s t r a c t Kindlin-2, as an integrin-interacting protein, was known to be required for the maintenance of cardiac structure and function in zebrafish. However, the mechanism remains unclear. We found that Kindlin-2 interacts and colocalizes with a-actinin-2 at the Z-disc of mouse cardiac muscles and there Kindlin-2 also interacts with b1 integrin. Knockdown of Kindlin-2 influences the association of b1 integrin with a-actinin-2 and disrupts the structure of the Z-disc and leads to cardiac dysfunction. Our data indicated that Kindlin-2 is a novel a-actinin-2-interacting protein and plays an important role in the regulation of cardiac structure and function.

Reactive oxygen species (ROS) are constantly produced in cells, an excess of which causes oxidative stress. ROS has been linked to regulation of the Hippo pathway; however, the underlying detailed mechanisms remain unclear. Here, we report that MOB1, a substrate of MST1/2 and co-activator of LATS1/2 in the canonical Hippo pathway, interacts with and is acetylated at lysine 11 by acetyltransferase CBP and deacetylated by HDAC6. MOB1-K11 acetylation stabilizes itself by reducing its binding capacity with E3 ligase Praja2 and subsequent ubiquitination. MOB1-K11 acetylation increases its phosphorylation and activates LATS1. Importantly, upstream oxidative stress signals promote MOB1 acetylation by suppressing CBP degradation, independent of MST1/2 kinase activity and HDAC6 deacetylation effect, thereby linking oxidative stress to activation of the Hippo pathway. Functionally, the acetylation-deficient mutant MOB1-K11R promotes lung cancer cell proliferation, migration and invasion in vitro and accelerates tumor growth in vivo, compared to the wild-type MOB1. Clinically, acetylated MOB1 corresponds to better prediction of overall survival in patients with non-small cell lung cancer. Therefore, as demonstrated, an oxidative stress-CBP regulatory axis controls MOB1-K11 acetylation and activates LATS1, thereby activating the Hippo pathway and suppressing YAP/TAZ nuclear translocation and tumor progression.

PET imaging that targets fibroblast activation protein (FAP) on the surface of cancer-associated fibroblasts has yielded promising tumor diagnostic results. FAP-2286 contains cyclic peptides as FAP-binding motifs to optimize tumor retention compared with the small-molecule FAP inhibitor (FAPI) series (FAPI-04/46). The aim of this study was to evaluate the diagnostic accuracy of 68 Ga-FAP-2286 to detect primary and metastatic lesions in patients with various types of cancer, compared with 18 F-FDG and 68 Ga-FAP-2286. Methods: Sixty-four patients with 15 types of cancer underwent 68 Ga-FAP-2286 PET/CT for initial assessment or detection of recurrence. For comparison, 63 patients underwent paired 68 Ga-FAP-2286 and 18 F-FDG PET/CT and 19 patients underwent paired 68 Ga-FAP-2286 and 68 Ga-FAPI-46 PET/CT. Lesion uptake was quantified as SUV max and tumor-to-background ratio. The Wilcoxon matched-pairs signed-rank test was used to compare SUV max between PET modalities, and the McNemar test was used to compare lesion detectability. Results: Uptake of 68 Ga-FAP-2286 was significantly higher than that of 18 F-FDG in primary tumors (median SUV max , 11.1 vs. 6.9; P , 0.001), lymph node metastases (median SUV max , 10.6 vs. 6.2; P , 0.001), and distant metastases, resulting in improved image contrast and lesion detectability. All primary tumors (46/46) were clearly visualized by 68 Ga-FAP-2286 PET/CT, whereas 9 of the 46 lesions could not be visualized by 18 F-FDG PET/CT. The lesion detection rate of 68 Ga-FAP-2286 PET/CT was superior to that of 18 F-FDG PET/CT for involved lymph nodes (98% [105/107] vs. 85% [91/107], P 5 0.001) and bone and visceral metastases (95% [162/171] vs. 67% [114/171], P , 0.001). 68 Ga-FAP-2286 yielded tumor uptake and lesion detection rates similar to those of 68 Ga-FAPI-46 in a subcohort of 19 patients. Conclusion: 68 Ga-FAP-2286 is a promising FAP-inhibitor derivative for safe cancer diagnosis, staging, and restaging. It may be a better alternative to 18 F-FDG for the cancer types that exhibit low-to-moderate uptake of 18 F-FDG, which include gastric, pancreatic, and hepatic cancers. In addition, 68 Ga-FAP-2286 and 68 Ga-FAPI-46 yielded comparable clinical results.

How cancer cells cope with high levels of replication stress during rapid proliferation is currently unclear. Here, we show that macrophage migration inhibitory factor (MIF) is a 3’ flap nuclease that translocates to the nucleus in S phase. Poly(ADP-ribose) polymerase 1 co-localizes with MIF to the DNA replication fork, where MIF nuclease activity is required to resolve replication stress and facilitates tumor growth. MIF loss in cancer cells leads to mutation frequency increases, cell cycle delays and DNA synthesis and cell growth inhibition, which can be rescued by restoring MIF, but not nuclease-deficient MIF mutant. MIF is significantly upregulated in breast tumors and correlates with poor overall survival in patients. We propose that MIF is a unique 3’ nuclease, excises flaps at the immediate 3’ end during DNA synthesis and favors cancer cells evading replication stress-induced threat for their growth.