Penfluridol inhibits melanoma growth and metastasis through enhancing von Hippel‒Lindau tumor suppressor-mediated cancerous inhibitor of protein phosphatase 2A (CIP2A) degradation.

Melanoma's high metastatic potential, especially to the brain, poses significant challenges to patient survival. The blood‒brain barrier (BBB) is a major obstacle to the effective treatment of melanoma brain metastases. We screened antipsychotic drugs capable of crossing the BBB and identified penfluridol (PF) as the most active candidate. PF reduced melanoma cell viability and induced apoptosis. In animal models, PF effectively inhibited melanoma growth and metastasis to the lung and brain. Using immunoprecipitation combined with high-resolution mass spectrometry, and other techniques such as drug affinity responsive target stability, we identified CIP2A as a direct binding protein of PF. CIP2A is highly expressed in melanoma and its metastases, and is linked to poor prognosis. PF can restore Protein Phosphatase 2A activity by promoting CIP2A degradation, thereby inhibiting several key oncogenic pathways, including AKT and c-Myc. Additionally, von Hippel‒Lindau (VHL) is the endogenous E3 ligase for CIP2A, and PF enhances the interaction between VHL and CIP2A, promoting the ubiquitin‒proteasome degradation of CIP2A, thereby inhibiting melanoma growth and metastasis. Overall, this study not only suggests PF's potential in treating melanoma and its brain metastases but also highlights CIP2A degradation as a therapeutic strategy for melanoma.

Copper-Catalyzed Intramolecular Decarboxylative C(sp2)-Heteroatom Cross-Couplings: Mechanism Insights and Synthetic Applications.

Decarboxylative C(sp2)-heteroatom cross-coupling reactions hold extraordinary potential for the sustainable preparation of biologically active scaffolds. Herein, we report a copper sulfate/1,10-phenathroline catalytic system for the decarboxylative intramolecular C(sp2)-O, C(sp2)-S, and C(sp2)-N coupling reactions leading to the construction of a series of benzo[b]furans, benzo[b]thiophenes, and indole derivatives from the corresponding coumarins, thiocoumarins, or quinolones, respectively. Our mechanistic study based on benzo[b]furan formation suggests a three-step process of the transformations, which consists of (i) base-mediated hydrolytic ring opening of coumarin, (ii) copper-oxygen co-initiated radical decarboxylation, and (iii) copper-catalyzed C-heteroatom cross coupling. Application of this method in the total synthesis of egonol, a bioactive natural product, was demonstrated successfully, with an overall yield of 51.7%.

Small-molecule-based targeted therapy in liver cancer.

Liver cancer is one of the most prevalent malignant tumors worldwide. According to the Barcelona Clinic Liver Cancer staging criteria, clinical guidelines provide tutorials to clinical management of liver cancer at their individual stages. However, most patients diagnosed with liver cancer are at advanced stage; therefore, many researchers conduct investigations on targeted therapy, aiming to improve the overall survival of these patients. To date, small-molecule-based targeted therapies are highly recommended (first line: sorafenib and lenvatinib; second line: regorafenib and cabozantinib) by current the clinical guidelines of the American Society of Clinical Oncology, European Society for Medical Oncology, and National Comprehensive Cancer Network. Herein, we summarize the small-molecule-based targeted therapies in liver cancer, including the approved and preclinical therapies as well as the therapies under clinical trials, and introduce their history of discovery, clinical trials, indications, and molecular mechanisms. For drug resistance, the revealed mechanisms of action and the combination therapies are also discussed. In fact, the known small-molecule-based therapies still have limited clinical benefits to liver cancer patients. Therefore, we analyze the current status and give our ideas for the urgent issues and future directions in this field, suggesting clues for novel techniques in liver cancer treatment.

The tumor-intrinsic role of the m6A reader YTHDF2 in regulating immune evasion.

Tumors evade attacks from the immune system through various mechanisms. Here, we identify a component of tumor immune evasion mediated by YTH domain-containing family protein 2 (YTHDF2), a reader protein that usually destabilizes m6A-modified mRNA. Loss of tumoral YTHDF2 inhibits tumor growth and prolongs survival in immunocompetent tumor models. Mechanistically, tumoral YTHDF2 deficiency promotes the recruitment of macrophages via CX3CL1 and enhances mitochondrial respiration of CD8+ T cells by impairing tumor glycolysis metabolism. Tumoral YTHDF2 deficiency promotes inflammatory macrophage polarization and antigen presentation in the presence of IFN-γ. In addition, IFN-γ induces autophagic degradation of tumoral YTHDF2, thereby sensitizing tumor cells to CD8+ T cell-mediated cytotoxicity. Last, we identified a small molecule compound that preferentially induces YTHDF2 degradation, which shows a potent antitumor effect alone but a better effect when combined with anti-PD-L1 or anti-PD-1 antibodies. Collectively, YTHDF2 appears to be a tumor-intrinsic regulator that orchestrates immune evasion, representing a promising target for enhancing cancer immunotherapy.

Exosomes rewire the cartilage microenvironment in osteoarthritis: from intercellular communication to therapeutic strategies.

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by cartilage loss and accounts for a major source of pain and disability worldwide. However, effective strategies for cartilage repair are lacking, and patients with advanced OA usually need joint replacement. Better comprehending OA pathogenesis may lead to transformative therapeutics. Recently studies have reported that exosomes act as a new means of cell-to-cell communication by delivering multiple bioactive molecules to create a particular microenvironment that tunes cartilage behavior. Specifically, exosome cargos, such as noncoding RNAs (ncRNAs) and proteins, play a crucial role in OA progression by regulating the proliferation, apoptosis, autophagy, and inflammatory response of joint cells, rendering them promising candidates for OA monitoring and treatment. This review systematically summarizes the current insight regarding the biogenesis and function of exosomes and their potential as therapeutic tools targeting cell-to-cell communication in OA, suggesting new realms to improve OA management.

Glycyrrhetinic acid restricts mitochondrial energy metabolism by targeting SHMT2.

Glycyrrhetinic acid (GA) is a natural product of licorice with mitochondria targeting properties and shows broad anticancer activities, but its targets and underlying mechanisms remain elusive. Here, we identified the mitochondrial enzyme serine hydroxymethyltransferase 2 (SHMT2) as a target of GA by using chemical proteomics. Binding to and inhibiting the activity of SHMT2 by GA were validated in vitro and in vivo. Knockout of SHMT2 or inhibiting SHMT2 with GA restricts mitochondrial energy supplies by downregulating mitochondrial oxidative phosphorylation (OXPHOS) and fatty acid ß-oxidation, and consequently suppresses cancer cell proliferation and tumor growth. Crystal structures of GA derivatives indicate that GA occupies SHMT2 folate-binding pocket and regulates SHMT2 activity. Modifications at GA carboxylic group with diamines significantly improved its anticancer potency, demonstrating GA as a decent structural template for SHMT2 inhibitor development.

Proteolysis-targeting chimeras (PROTACs) in cancer therapy.

Proteolysis-targeting chimeras (PROTACs) are engineered techniques for targeted protein degradation. A bifunctional PROTAC molecule with two covalently-linked ligands recruits target protein and E3 ubiquitin ligase together to trigger proteasomal degradation of target protein by the ubiquitin-proteasome system. PROTAC has emerged as a promising approach for targeted therapy in various diseases, particularly in cancers. In this review, we introduce the principle and development of PROTAC technology, as well as the advantages of PROTACs over traditional anti-cancer therapies. Moreover, we summarize the application of PROTACs in targeting critical oncoproteins, provide the guidelines for the molecular design of PROTACs and discuss the challenges in the targeted degradation by PROTACs.

Microtubule affinity regulating kinase 4 promoted activation of the NLRP3 inflammasome-mediated pyroptosis in periodontitis.

BACKGROUND: Microtubule dynamics plays a crucial role in the spatial arrangement of cell organelles and activation of the NLRP3 inflammasome. PURPOSE: This study aimed to explore whether microtubule affinity regulating kinase 4 (MARK4) can be a therapeutic target of periodontitis by affecting microtubule dynamics and NLRP3 inflammasome-mediated pyroptosis in macrophages. MATERIALS AND METHODS: The NLRP3 inflammasome-related genes and MARK4 were measured in the healthy and inflamed human gingival tissues. Bone marrow-derived macrophages (BMDMs) were infected with Porphyromonas gingivalis, while the MARK4 inhibitors (OTSSP167 and Compound 50) and small interference RNA were utilized to restrain MARK4. Apoptosis-associated speck-like protein (ASC) speck was detected by confocal, and levels of interleukin-1ß (IL-1ß), as well as IL-18, were assessed by ELISA. RESULTS: Increased staining and transcription of MARK4, NLRP3, ASC, and Caspase-1 were observed in the inflamed gingiva. P. gingivalis infection promoted MARK4 expression and the NLRP3 inflammasome in BMDMs. Inhibition of MARK4 decreased LDH release, IL-1ß and IL-18 production, ASC speck formation, and the pyroptosis-related genes transcription. Furthermore, MARK4 inhibition reduced microtubule polymerization and acetylation in P. gingivalis-infected BMDMs. CONCLUSIONS: MARK4 promoted NLRP3 inflammasome activation and pyroptosis in P. gingivalis-infected BMDMs by affecting microtubule dynamics. MARK4 inhibition might be a potential target in regulating the NLRP3 inflammasome during periodontitis progress.

PHLDB2 Mediates Cetuximab Resistance via Interacting With EGFR in Latent Metastasis of Colorectal Cancer.

BACKGROUND & AIMS: Latent metastasis of colorectal cancer (CRC) frequently develops months or years after primary surgery, followed by adjuvant therapies, and may progress rapidly even with targeted therapy administered, but the underlying mechanism remains unclear. Here, we aim to explore the molecular basis for the aggressive behavior of latent metastasis in CRC. METHODS: Transcriptional profiling and pathway enrichment analysis of paired primary and metastatic tumor samples were performed. The underlying mechanisms of pleckstrin homology-like domain, family B, member 2 (PHLDB2) in CRC were investigated by RNA immunoprecipitation assay, immunohistochemistry, mass spectrometry analysis, and Duolink in situ proximity ligation assay (Sigma-Aldrich, Shanghai, China). The efficacy of targeting PHLDB2 in cetuximab treatment was elucidated in CRC cell lines and mouse models. RESULTS: Based on the transcriptional profile of paired primary and metastatic tumor samples, we identified PHLDB2 as a potential regulator in latent liver metastasis. A detailed mechanistic study showed that chemotherapeutic agent-induced oxidative stress promotes methyltransferase-like 14 (METTL14)-mediated N6-methyladenosine modification of PHLDB2 messenger RNA, facilitating its protein expression. Up-regulated PHLDB2 stabilizes epidermal growth factor receptor (EGFR) and promotes its nuclear translocation, which in turn results in EGFR signaling activation and consequent cetuximab resistance. Moreover, Arg1163 (R1163) of PHLDB2 is crucial for interaction with EGFR, and the R1163A mutation abrogates its regulatory function in EGFR signaling. CONCLUSIONS: PHLDB2 plays a crucial role in cetuximab resistance and is proposed to be a potential target for the treatment of CRC.

Three new 3-formyl-2-arylbenzofurans from Itea yunnanensis and their anti-hepatocellular carcinoma effects.

Five 3-formyl-2-arylbenzofuran derivatives, including three new compounds (1-3) and two known analogues (4-5), were identified from the 95% EtOH extract of Itea yunnanensis. Extensive spectroscopic analyses were performed for the structure elucidation of all new benzofurans, and single-crystal X-ray diffraction analyses were further employed for the structure verification of iteafuranals C (1) and D (2). In MTT assay, iteafuranal E (3) and iteafuranal A (4) displayed significant growth inhibition effect on SK-Hep-1 cells with IC50 values of 5.365 µM and 6.013 µM, respectively. The colony formation assay of 3 and 4 further confirmed their remarkable inhibitory effect on cell growth. Preliminary mechanism study demonstrated that 3 remarkably down-regulated the phosphorylation level of ERK, which suggested 3 could inhibit cell growth and induce apoptosis of SK-Hep-1 cells by blocking RAS/RAF/MEK/ERK signaling pathway. This study highlighted the potential of 3-fomyl-2-benzofuran derivatives as novel lead compounds to treat Hepatocellular carcinoma.[Formula: see text].

Prolyl Isomerase Pin1 in Human Cancer: Function, Mechanism, and Significance.

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) is an evolutionally conserved and unique enzyme that specifically catalyzes the cis-trans isomerization of phosphorylated serine/threonine-proline (pSer/Thr-Pro) motif and, subsequently, induces the conformational change of its substrates. Mounting evidence has demonstrated that Pin1 is widely overexpressed and/or overactivated in cancer, exerting a critical influence on tumor initiation and progression via regulation of the biological activity, protein degradation, or nucleus-cytoplasmic distribution of its substrates. Moreover, Pin1 participates in the cancer hallmarks through activating some oncogenes and growth enhancers, or inactivating some tumor suppressors and growth inhibitors, suggesting that Pin1 could be an attractive target for cancer therapy. In this review, we summarize the findings on the dysregulation, mechanisms, and biological functions of Pin1 in cancer cells, and also discuss the significance and potential applications of Pin1 dysregulation in human cancer.

Circular RNAs in Cancer: Biogenesis, Function, and Clinical Significance.

Circular RNA (circRNA) is a class of single-stranded molecules with tissue/development-specific expression patterns. Unlike linear RNA, circRNA forms a covalently closed loop produced from 'back-splicing' of primary transcripts, conferring on them inherent resistance to exonucleolytic RNA decay. Increasing evidence demonstrates that many circRNAs exert important biological functions by acting as miRNA inhibitors ('sponges'), protein 'decoys', or by encoding small peptides. Importantly, circRNAs are aberrantly expressed in cancer and play indispensable oncogenic or tumor suppressive roles during tumor development and progression. In this review, we summarize the biogenesis, turnover, and involvements of circRNAs in cancer and also discuss their potential as diagnostic biomarkers or therapeutic targets.

PDLIM1 Inhibits Tumor Metastasis Through Activating Hippo Signaling in Hepatocellular Carcinoma.

BACKGROUND AND AIMS: Tumor metastasis is a major factor of high recurrence and mortality in hepatocellular carcinoma (HCC), but its underlying mechanism remains elusive. We report that PDZ and LIM domain protein 1 (PDLIM1) is significantly down-regulated in metastatic human HCC tissues, which predicts unfavorable prognosis, suggesting that PDLIM1 may play an important inhibitory role during HCC metastasis. APPROACH AND RESULTS: Functional studies indicate that PDLIM1 knockdown induces epithelial-to-mesenchymal transition (EMT) of HCC cells, elevates their invasive capacity, and promotes metastasis in vitro and in vivo, whereas overexpression of PDLIM1 exhibits opposite phenotypes. Mechanistically, PDLIM1 competitively binds to the cytoskeleton cross-linking protein alpha-actinin 4 (ACTN4), leading to the disassociation of ACTN4 from F-actin, thus preventing F-actin overgrowth. In contrast, loss of PDLIM1 induces excessive F-actin formation, resulting in dephosphorylation of large tumor suppressor kinase 1 and activation of Yes-associated protein, thereby promoting HCC metastasis. Moreover, Asn145 (N145) of PDLIM1 is critical for its interaction with ACTN4, and N145A mutation abolishes its regulatory function in Hippo signaling and HCC metastasis. CONCLUSIONS: Our findings indicate that PDLIM1 suppresses HCC metastasis by modulating Hippo signaling, suggesting that PDLIM1 may be a potential prognostic marker for metastatic HCC.

An Unbiased Immunoaffinity-Based Strategy for Profiling Covalent Drug Targets In Vivo.

Activity-based chemical proteomics approaches used for identifying cellular targets of drugs are mainly dependent on the availability of probes derived from drugs. However, all chemical probes are structurally different from the drugs themselves and cannot fully mimic the real actions of drugs in cells. Here we present a concise and unbiased immunoaffinity-based strategy for identifying covalent drug targets in vivo. By using the specific antibody, we not only confirm the well-known ibrutinib-binding target BTK, but also identify some previously undescribed strongly binding proteins, such as CKAP4 in human cell lines and TAP1 in mouse organs. The observed target profiles between species may partially explain why certain drug candidates are very effective in mice but not in humans. This approach avoids the chemical modification of drugs, eliminates the nonspecific bindings of chemical probes, and allows to unbiasedly decode the underlying mechanisms of action of covalent drugs.

MicroRNA Biogenesis is Enhanced by Liposome-Encapsulated Pin1 Inhibitor in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is in an urgent need of new, effective therapies to reduce morbidity and mortality. We have previously demonstrated that peptidyl-prolyl cis/trans isomerase Pin1 is a potential target for HCC therapy, due to its pivotal role in HCC development through regulating miRNA biogenesis, and discovered the small molecule API-1 as a novel and specific Pin1 inhibitor. Despite its significant anti-HCC activity, the low water solubility and in vivo bioavailability of API-1 limit its clinical application. To address these issues, we herein developed a liposomal formulation of API-1 to improve API-1 delivery and enhance its anti-HCC efficacy. Methods: We designed and developed a nanoscale liposomal formulation of API-1, named as API-LP. Subsequently, the mean diameter, polydispersity, zeta potential, encapsulation efficiency and thermal properties of the optimization API-LP were characterized. The enhanced anti-HCC activity and the molecular mechanism of API-LP were investigated both in vitro and in vivo. Finally, the safety and pharmacokinetic property of API-LP were evaluated systematically. Results: API-LP had good formulation characteristics and exhibited an enhanced in vitro activity of suppressing proliferation and migration of HCC cells when compared with free API-1. The mechanism study showed that API-LP upregulated miRNA biogenesis via inhibiting Pin1 activity followed by restoring the nucleus-to-cytoplasm export of XPO5. Because of the increased delivery efficiency, API-LP displayed a stronger ability to promote miRNA biogenesis than free API-1. Importantly, API-LP displayed higher systemic exposure than free API-1 in mice without apparent toxicity, resulting in an enhanced tumor inhibition in xenograft mice. Conclusion: The development and assessment of API-LP provide an attractive and safe anti-HCC agent, highlighting the miRNA-based treatment for human cancers.

Discovery of Coumarin as Microtubule Affinity-Regulating Kinase 4 Inhibitor That Sensitize Hepatocellular Carcinoma to Paclitaxel.

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide. Nowadays, pharmacological therapy for HCC is in urgent needs. Paclitaxel is an effective drug against diverse solid tumors, but commonly resisted in HCC patients. We recently have disclosed that microtubule affinity-regulating kinase 4 (MARK4) increases the microtubule dynamics and confers paclitaxel resistance in HCC, suggesting MARK4 as an attractive target to overcome paclitaxel resistance. Herein, we synthesized and identified coumarin derivatives 50 as a novel MARK4 inhibitor. Biological evaluation indicated compound 50 directly interacted with MARK4 and inhibited its activity in vitro, suppressed cell viability and induced apoptosis of HCC cells in a MARK4-dependent manner. Importantly, compound 50 significantly increased the drug response of paclitaxel treatment to HCC cells, providing a promise strategy to HCC treatment and broadening the application of paclitaxel in cancer therapy.

Circular RNA F-circSR derived from SLC34A2-ROS1 fusion gene promotes cell migration in non-small cell lung cancer.

Cancer-associated chromosomal translocations are reported to generate oncogenic circular RNA (circRNA), contributing to tumorigenesis. The fusion gene SLC34A2-ROS1 (solute carrier family 34 member 2 and ROS proto-oncogene 1) plays an important role in non-small cell lung cancer (NSCLC) progression. However, whether SLC34A2-ROS1 gene can produce circRNA remains unknown. Here, we identified two novel circRNAs (F-circSR1 and F-circSR2) generated from SLC34A2-ROS1 fusion gene, while F-circSR1 has higher expression than F-circSR2. Functional studies through gain- and loss-of-function strategies showed that both F-circSRs promote cell migration in lung cancer cells, whereas they have little effect on cell proliferation. Using the minigene GFP reporter assay, we verified that the flanking complementary sequences with canonical splicing sites are essential for F-circSR biogenesis. Therefore, our findings demonstrate the oncogenic role of F-circSR in NSCLC and highlight its therapeutic potential.

Novel ROR1 inhibitor ARI-1 suppresses the development of non-small cell lung cancer.

Limited drug response and severe drug resistance confer the high mortality of non-small-cell lung cancer (NSCLC), a leading cause of cancer death worldwide. There is an urgent need for novel treatment against NSCLC. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is aberrantly overexpressed and participats in NSCLC development and EGFR-TKIs-induced drug resistance. Increasing evidences indicate that oncogenic ROR1 is a potential target for NSCLC therapy. However, nearly no ROR1 inhibitor was reported until now. Here, combining the computer-aided drug design and cell-based activity screening, we discover (R)-5,7-bis(methoxymethoxy)-2-(4-methoxyphenyl)chroman-4-one (ARI-1) as a novel ROR1 inhibitor. Biological evaluation demonstrates that ARI-1 specifically targets the extracellular frizzled domain of ROR1 and potently suppresses NSCLC cell proliferation and migration by regulating PI3K/AKT/mTOR signaling in a ROR1-dependent manner. Moreover, ARI-1 significantly inhibits tumor growth in vivo without obvious toxicity. Intriguingly, ARI-1 is effective to EGFR-TKIs-resistant NSCLC cells with high ROR1 expression. Therefore, our work suggests that the ROR1 inhibitor ARI-1 is a novel drug candidate for NSCLC treatment, especially for EGFR-TKIs-resisted NSCLC with high ROR1 expression.