Metastasis is responsible for the majority of deaths of patients with cancer. However, mechanisms governing metastasis in colorectal cancer remain largely unknown. Here we investigated how colorectal cancer cells acquire metastatic potential using a novel mouse model of colorectal cancer that spontaneously develops liver metastasis, generated by introducing sporadic mutations of Ctnnb1, Kras, Trp53, and Smad4 (CKPS) genes. Proteomic analyses revealed elevated expression of colorectal cancer stem cell markers ALCAM (CD166) and PROM1 (CD133) in colorectal cancer cells from the metastatic model compared with those from a nonmetastatic model. Spleen-to-liver metastasis assays using colorectal cancer cells derived from the CKPS model (CKPS cells) demonstrated the functional importance of ALCAM and PROM1 in initiating metastasis. Genetic and pharmacologic analyses using CKPS cells in 2D and spheroid culture revealed that expression of ALCAM and PROM1 is regulated positively and negatively by the cAMP/PKA/CREB and TGFβ/SMAD4 pathways, respectively. Consistently, phospho-CREB was expressed in both primary and metastatic lesions of CKPS mice and patients with colorectal cancer, and knockout of CREB in CKPS cells reduced their spheroid-forming and metastasis-initiating abilities. Treatment with a CREB inhibitor potentiated the effect of irinotecan in suppressing liver metastasis by CKPS cells. These results reveal the essential roles of ALCAM and PROM1, as well as their upstream regulators, the cAMP/PKA/CREB and TGFβ/SMAD4 pathways, in maintaining the stemness and metastatic potential of colorectal cancer cells and indicate that CREB inhibition may be a potential therapeutic strategy against metastatic colorectal cancer. Significance: This study identifies signaling pathways essential for maintaining the stemness and metastatic potential of colorectal cancer cells and proposes CREB as a therapeutic target in metastatic colorectal cancer.

Cancer cachexia is a complex metabolic disorder accounting for ~20% of cancer-related deaths, yet its metabolic landscape remains unexplored. Here, we report a decrease in B vitamin-related liver enzymes as a hallmark of systemic metabolic changes occurring in cancer cachexia. Metabolomics of multiple mouse models highlights cachexia-associated reductions of niacin, vitamin B6, and a glycine-related subset of one-carbon (C1) metabolites in the liver. Integration of proteomics and metabolomics reveals that liver enzymes related to niacin, vitamin B6, and glycine-related C1 enzymes dependent on B vitamins decrease linearly with their associated metabolites, likely reflecting stoichiometric cofactor-enzyme interactions. The decrease of B vitamin-related enzymes is also found to depend on protein abundance and cofactor subtype. These metabolic/proteomic changes and decreased protein malonylation, another cachexia feature identified by protein post-translational modification analysis, are reflected in blood samples from mouse models and gastric cancer patients with cachexia, underscoring the clinical relevance of our findings.

In response to drought stress, land plants close their stomata to minimize transpiration. This action precedes a gradual accumulation of the stress hormone abscisic acid (ABA) that enhances plant drought tolerance. However, the molecular mechanisms that cause the time lag between the onset of stomatal closure and ABA accumulation and coordinate these two phases remain unexplained. Here, we found that Arabidopsis thaliana loss-of-function CLAVATA3/ENDOSPERM SURROUNDING REGION 5 (CLE5) mutants are less tolerant to drought. The CLE5 dodecapeptide (CLE5p) acts as a local signal to induce stomatal closure by binding to the LEUCINE-RICH REPEAT RECEPTOR-LIKE KINASE (LRR-RLK) receptor complex, BARELY ANY MERISTEM 1 (BAM1)–GUARD CELL HYDROGEN PEROXIDE-RESISTANT 1 (GHR1), in guard cells. The BAM1–GHR1–CLE5p module directly phosphorylates two SNF1-related protein kinases, OPEN STOMATA1 (SRK2E) and SRK2D, the central regulators of drought responses in plants, to regulate stomatal movement and drought-responsive gene expression without stimulating ABA biosynthesis or ROS accumulation. Our findings mark a critical step in understanding how plants promptly counteract environmental stresses. The CLEp–LRR-RLK signalling components are highly conserved across plant phyla, suggesting that peptide-mediated rapid stomatal closure is a widespread survival strategy and can be exploited to generate drought-resistant crops.

The Ser/Leu-swapped genetic code can act as a genetic firewall, mitigating biohazard risks arising from horizontal gene transfer in genetically modified organisms. Our prior work demonstrated the orthogonality of this swapped code to the standard genetic code using a cell-free translation system comprised of 21 in vitro transcribed tRNAs. In this study, to advance this system for protein engineering, we introduce a natural/in vitro transcribed-hybrid tRNA set. This set combines natural tRNAs from Escherichia coli (excluding Ser, Leu, and Tyr) and in vitro transcribed tRNAs, encompassing anticodon-swapped tRNA^Ser_GAG and tRNA^Leu_GGA. This approach reduces the number of in vitro transcribed tRNAs required from 21 to only 4. In this optimized system, the production of a model protein, superfolder green fluorescent protein, increases to 3.5-fold. With this hybrid tRNA set, the Ser/Leu-swapped cell-free translation system will stand as a potent tool for protein production with reduced biohazard concerns in future biological endeavors.

Inactivation of tumor-suppressive Hippo signaling pathway is frequently observed in mesothelioma, which leads to the activation of yes-associated protein (YAP) and TAZ (also known as WW domain–containing transcription regulator 1; YAP/TAZ) transcriptional coactivators. YAP/TAZ form complexes with TEAD family members, DNA-binding proteins, to activate transcription, which promotes cancer cell growth and proliferation. Recently developed TEAD inhibitors exhibit antitumor activity by inhibiting the formation of the transcription complex through binding to TEAD; however, the antitumor activity of TEAD inhibitors against mesothelioma remains to be fully elucidated. Here, we show that the TEAD inhibitor K-975 acts as a pan-TEAD inhibitor and selectively inhibits the binding of TEAD-binding proteins, especially YAP/TAZ, in mesothelioma cells. In studies using a panel of mesothelioma cell lines, K-975 showed a significant growth inhibitory effect on Hippo-inactivated mesothelioma cells, but some of these cell lines exhibited primary resistance to K-975. Differential gene expression analysis revealed that cells resistant to K-975 exhibited activation of MYC signaling in the presence of K-975, and cells overexpressed with MYC showed strong drug resistance, in vitro and in vivo. Our study revealed the features of a subset of mesothelioma cells that proliferate in a TEAD-independent manner and provides important insights for the successful development of therapeutic strategies for mesothelioma with Hippo pathway inactivation.