cGAS suppresses hepatocellular carcinoma independent of its cGAMP synthase activity.

Cyclic GMP-AMP synthase (cGAS) is a key innate immune sensor that recognizes cytosolic DNA to induce immune responses against invading pathogens. The role of cGAS is conventionally recognized as a nucleotidyltransferase to catalyze the synthesis of cGAMP upon recognition of cytosolic DNA, which leads to the activation of STING and production of type I/III interferon to fight against the pathogen. However, given that hepatocytes are lack of functional STING expression, it is intriguing to define the role of cGAS in hepatocellular carcinoma (HCC), the liver parenchymal cells derived malignancy. In this study, we revealed that cGAS was significantly downregulated in clinical HCC tissues, and its dysregulation contributed to the progression of HCC. We further identified cGAS as an immune tyrosine inhibitory motif (ITIM) containing protein, and demonstrated that cGAS inhibited the progression of HCC and increased the response of HCC to sorafenib treatment by suppressing PI3K/AKT/mTORC1 pathway in cellular and animal models. Mechanistically, cGAS recruits SH2-containing tyrosine phosphatase 1 (SHP1) via ITIM, and dephosphorylates p85 in phosphatidylinositol 3-kinase (PI3K), which leads to the suppression of AKT-mTORC1 pathway. Thus, cGAS is identified as a novel tumor suppressor in HCC via its function independent of its conventional role as cGAMP synthase, which indicates a novel therapeutic strategy for advanced HCC by modulating cGAS signaling.

Paucatalinone A from Paulownia Catalpifolia Gong Tong Elicits mitochondrial-mediated cancer cell death to combat osteosarcoma.

As the global cancer burden escalates, the search for alternative therapies becomes increasingly vital. Natural products, particularly plant-derived compounds, have emerged as promising alternatives to conventional cancer treatments due to their diverse bioactivities and favorable biosafety profiles. Here, we investigate Paucatalinone A, a newly discovered geranylated flavanone derived from the fruit of Paulownia Catalpifolia Gong Tong, notable for its significant anti-cancer properties. We revealed the capability of Paucatalinone A to induce apoptosis in osteosarcoma cells and deciphered its underlying mechanisms. Our findings demonstrate that Paucatalinone A substantially augments apoptosis, inhibits cell proliferation, and demonstrates a pronounced anti-tumor effect in a murine model of osteosarcoma. Mechanistically, Paucatalinone A disrupts calcium homeostasis and exacerbates intracellular reactive oxygen species accumulation, leading to mitochondrial impairment, cytoskeletal collapse, and caspase-dependent apoptotic cell death. This study underscores the potential of Paucatalinone A in initiating apoptosis in cancer cells and highlights the therapeutic efficacy of plant-derived agents in treating osteosarcoma, offering a viable approach for managing other intractable cancers.

mRNA-Laden Lipid-Nanoparticle-Enabled in Situ CAR-Macrophage Engineering for the Eradication of Multidrug-Resistant Bacteria in a Sepsis Mouse Model.

Sepsis, which is the most severe clinical manifestation of acute infection and has a mortality rate higher than that of cancer, represents a significant global public health burden. Persistent methicillin-resistant Staphylococcus aureus (MRSA) infection and further host immune paralysis are the leading causes of sepsis-associated death, but limited clinical interventions that target sepsis have failed to effectively restore immune homeostasis to enable complete eradication of MRSA. To restimulate anti-MRSA innate immunity, we developed CRV peptide-modified lipid nanoparticles (CRV/LNP-RNAs) for transient in situ programming of macrophages (MΦs). The CRV/LNP-RNAs enabled the delivery of MRSA-targeted chimeric antigen receptor (CAR) mRNA (SasA-CAR mRNA) and CASP11 (a key MRSA intracellular evasion target) siRNA to MΦs in situ, yielding CAR-MΦs with boosted bactericidal potency. Specifically, our results demonstrated that the engineered MΦs could efficiently phagocytose and digest MRSA intracellularly, preventing immune evasion by the "superbug" MRSA. Our findings highlight the potential of nanoparticle-enabled in vivo generation of CAR-MΦs as a therapeutic platform for multidrug-resistant (MDR) bacterial infections and should be confirmed in clinical trials.

Dual mRNA co-delivery for in situ generation of phagocytosis-enhanced CAR macrophages augments hepatocellular carcinoma immunotherapy.

Hepatocellular carcinoma (HCC) is a prevalent and lethal disease, and tumor regression rarely occurs in advanced HCC patients due to limited effective therapies. Given the enrichment of macrophages in HCC and their role in tumor immunity, transforming them into chimeric antigen receptor macrophages (CAR-Ms) is thought to increase HCC cell-directed phagocytosis and tumoricidal immunity. To test this hypothesis, mRNA encoding CAR is encapsulated in a lipid nanoparticle (LNP) that targets liver macrophages. Notably, the LNPs adsorb specific plasma proteins that enable them to target HCC-associated macrophages. Moreover, mRNA encoding Siglec-G lacking ITIMs (Siglec-GΔITIMs) is codelivered to liver macrophages by LNP to relieve CD24-mediated CAR-Ms immune suppression. Mice treated with LNPs generating CAR-Ms as well as CD24-Siglec-G blockade significantly elevate the phagocytic function of liver macrophages, reduce tumor burden and increase survival time in an HCC mouse model. Arguably, our work suggests an efficacious and flexible strategy for the treatment of HCC and warrants further rigorous evaluation in clinical trials.

cGAS Mediates Inflammation by Polarizing Macrophages to M1 Phenotype via the mTORC1 Pathway.

Cyclic GMP-AMP synthase (cGAS), as a cytosolic DNA sensor, plays a crucial role in antiviral immunity, and its overactivation induces excess inflammation and tissue damage. Macrophage polarization is critically involved in inflammation; however, the role of cGAS in macrophage polarization during inflammation remains unclear. In this study, we demonstrated that cGAS was upregulated in the LPS-induced inflammatory response via the TLR4 pathway, and cGAS signaling was activated by mitochondria DNA in macrophages isolated from C57BL/6J mice. We further demonstrated that cGAS mediated inflammation by acting as a macrophage polarization switch, which promoted peritoneal macrophages and the bone marrow-derived macrophages to the inflammatory phenotype (M1) via the mitochondrial DNA-mTORC1 pathway. In vivo studies verified that deletion of Cgas alleviated sepsis-induced acute lung injury by promoting macrophages to shift from the M1 phenotype to the M2 phenotype. In conclusion, our study demonstrated that cGAS mediated inflammation by regulating macrophage polarization through the mTORC1 pathway, and it further provided a potential therapeutic strategy for inflammatory diseases, especially sepsis-induced acute lung injury.

Convection-enhanced delivery of nanoencapsulated gene locoregionally yielding ErbB2/Her2-specific CAR-macrophages for brainstem glioma immunotherapy.

Locoregional delivery of chimeric antigen receptor (CAR)-modified T (CAR-T) cells has emerged as a promising strategy for brain tumors. However, the complicated ex vivo cell manufacturing procedures and the rapid progression of the disease have limited its broader applications. Macrophages (MΦs) exhibit unique effector functions and a high degree of infiltration within the solid tumor microenvironment (TME), especially in the brain, where MΦs function as structural support, and the main immune effector cells of the CNS represent 5-12% of brain cells. Here, we report a synthetic universal DNA nanocarrier for in situ genetic editing of intratumoral MΦs with an ErbB2-specific CAR to direct their phagocytic activity towards tumors and subsequently initiate a locoregional antitumor immune response. Specifically, we demonstrated that when delivered locoregionally, the RP-182 peptide, located in the shell of a nanoparticle, targeted MΦs and reprogrammed M2-like tumor-associated macrophages (TAMs) to an antitumor M1-like phenotype. Subsequently, the CAR gene-laden DNA nanocomplex can be used to introduce ErbB2-targeted CAR, and the generated CAR-MΦs then act as "living" cures, thereby serially clearing the invasive tumor cells. Our work demonstrates a practical antitumor immunotherapy for brainstem gliomas (BSGs) that may be broadly applicable for patients suffering from other ErbB2-positive solid malignancies.

Metabolic Modulation of Intracellular Ammonia via Intravesical Instillation of Nanoporter-Encased Hydrogel Eradicates Bladder Carcinoma.

Tumor protein 53 (TP53) mutation in bladder carcinoma (BC), upregulates the transcription of carbamoyl phosphate synthetase 1 (CPS1), to reduce intracellular ammonia toxicity. To leverage ammonia combating BC, here, an intravesically perfusable nanoporter-encased hydrogel system is reported. A biomimetic fusogenic liposomalized nanoporter (FLNP) that is decorated with urea transporter-B (UT-B) is first synthesized with protonated chitosan oligosaccharide for bladder tumor-targeted co-delivery of urease and small interfering RNA targeting CPS1 (siCPS1). Mussel-inspired hydrogel featured with dual functions of bio-adhesion and injectability is then fabricated as the reservoir for intravesical immobilization of FLNP. It is found that FLNP-mediated UT-B immobilization dramatically induces urea transportation into tumor cells, and co-delivery of urease and siCPS1 significantly boosts ammonia accumulation in tumor inducing cell apoptosis. Treatment with hybrid system exhibits superior anti-tumor effect in orthotopic bladder tumor mouse model and patient-derived xenograft model, respectively. Combined with high-protein diet, the production of urinary urea increases, leading to an augmented intracellular deposition of ammonia in BC cells, and ultimately an enhanced tumor inhibition. Together, the work establishes that cascade modulation of ammonia in tumor cells could induce tumor apoptosis and may be a practical strategy for eradication of TP53-mutated bladder cancer.

Remodeling articular immune homeostasis with an efferocytosis-informed nanoimitator mitigates rheumatoid arthritis in mice.

Massive intra-articular infiltration of proinflammatory macrophages is a prominent feature of rheumatoid arthritis (RA) lesions, which are thought to underlie articular immune dysfunction, severe synovitis and ultimately joint erosion. Here we report an efferocytosis-informed nanoimitator (EINI) for in situ targeted reprogramming of synovial inflammatory macrophages (SIMs) that thwarts their autoimmune attack and reestablishes articular immune homeostasis, which mitigates RA. The EINI consists of a drug-based core with an oxidative stress-responsive phosphatidylserine (PtdSer) corona and a shell composed of a P-selectin-blocking motif, low molecular weight heparin (LMWH). When systemically administered, the LMWH on the EINI first binds to P-selectin overexpressed on the endothelium in subsynovial capillaries, which functions as an antagonist, disrupting neutrophil synovial trafficking. Due to the strong dysregulation of the synovial microvasculature, the EINI is subsequently enriched in the joint synovium where the shell is disassembled upon the reactive oxygen species stimulation, and PtdSer corona is then exposed. In an efferocytosis-like manner, the PtdSer-coroneted core is in turn phagocytosed by SIMs, which synergistically terminate SIM-initiated pathological cascades and serially reestablish intra-articular immune homeostasis, conferring a chondroprotective effect. These findings demonstrate that SIMs can be precisely remodeled via the efferocytosis-mimetic strategy, which holds potential for RA treatment.

TRIM50 promotes NLRP3 inflammasome activation by directly inducing NLRP3 oligomerization.

Tripartite motif protein (TRIM) 50 is a new member of the tripartite motif family, and its biological function and the molecular mechanism it is involved in remain largely unknown. The NOD-like receptor family protein (NLRP)3 inflammasome is actively involved in a wide array of biological processes while mechanisms of its regulation remain to be fully clarified. Here, we demonstrate the role of TRIM50 in NLRP3 inflammasome activation. In contrast to the conventional E3 ligase functions of TRIM proteins, TRIM50 mediates direct oligomerization of NLRP3, thereby suppressing its ubiquitination and promoting inflammasome activation. Mechanistically, TRIM50 directly interacts with NLRP3 through its RING domain and induces NLRP3 oligomerization via its coiled-coil domain. Finally, we show that TRIM50 promotes NLRP3 inflammasome-mediated diseases in mice. We thus reveal a novel regulatory mechanism of NLRP3 via TRIM50 and suggest that modulating TRIM50 might represent a therapeutic strategy for NLRP3-dependent pathologies.

Intracavity generation of glioma stem cell-specific CAR macrophages primes locoregional immunity for postoperative glioblastoma therapy.

Glioblastoma multiforme (GBM) remains incurable despite aggressive implementation of multimodal treatments after surgical debulking. Almost all patients with GBM relapse within a narrow margin around the initial resected lesion due to postsurgery residual glioma stem cells (GSCs). Tracking and eradicating postsurgery residual GSCs is critical for preventing postoperative relapse of this devastating disease, yet effective strategies remain elusive. Here, we report a cavity-injectable nanoporter-hydrogel superstructure that creates GSC-specific chimeric antigen receptor (CAR) macrophages/microglia (MΦs) surrounding the cavity to prevent GBM relapse. Specifically, we demonstrate that the CAR gene-laden nanoporter in the hydrogel can introduce GSC-targeted CAR genes into MΦ nuclei after intracavity delivery to generate CAR-MΦs in mouse models of GBM. These CAR-MΦs were able to seek and engulf GSCs and clear residual GSCs by stimulating an adaptive antitumor immune response in the tumor microenvironment and prevented postoperative glioma relapse by inducing long-term antitumor immunity in mice. In an orthotopic patient-derived glioblastoma humanized mouse model, the combined treatment with nanoporter-hydrogel superstructure and CD47 antibody increased the frequency of positive immune responding cells and suppressed the negative immune regulating cells, conferring a robust tumoricidal immunity surrounding the postsurgical cavity and inhibiting postoperative glioblastoma relapse. Therefore, our work establishes a locoregional treatment strategy for priming cancer stem cell-specific tumoricidal immunity with broad application in patients suffering from recurrent malignancies.

Inhaled mRNA Nanoformulation with Biogenic Ribosomal Protein Reverses Established Pulmonary Fibrosis in a Bleomycin-Induced Murine Model.

Idiopathic pulmonary fibrosis (IPF), a lethal respiratory disease with few treatment options, occurs due to repetitive microinjuries to alveolar epithelial cells (AECs) and progresses with an overwhelming deposition of extracellular matrix (ECM), ultimately resulting in fibrotic scars and destroyed the alveolar architecture. Here, an inhaled ribosomal protein-based mRNA nanoformulation is reported for clearing the intrapulmonary ECM and re-epithelializing the disrupted alveolar epithelium, thereby reversing established fibrotic foci in IPF. The nanoformulation is sequentially assembled by a ribosomal protein-condensed mRNA core, a bifunctional peptide-modified corona and keratinocyte growth factor (KGF) with a PEGylated shielding shell. When inhaled via a nebulizer, the nanoformulations carried by microdrops are deposited in the alveoli, and penetrate into fibrotic foci, where the outer KGFs are detached after matrix metalloproteinase 2 (MMP2) triggering. The RGD motif-grafted cores then expose and specifically target the integrin-elevated cells for the intracellular delivery of mRNA. Notably, repeated inhalation of the nanoformulations accelerates the clearance of locoregional collagen by boosting the intralesional expression of MMP13 and alveolar re-epithelialization mediated by KGFs, which synergistically ameliorates the lung function of a bleomycin-induced murine model. Therefore, this work provides an alternative mRNA-inhalation delivery strategy, which shows great potential for the treatment of IPF.

FGFR3 Destabilizes PD-L1 via NEDD4 to Control T-cell-Mediated Bladder Cancer Immune Surveillance.

Fibroblast growth factor receptor 3 (FGFR3) is frequently activated by mutation or overexpression, and it is a validated therapeutic target in urothelial carcinoma (UC) of the bladder. However, the role and detailed molecular mechanism of FGFR3 in the immune microenvironment of bladder cancer remain largely unknown. Here, we demonstrate that inhibition of FGFR3 in FGFR3-activated bladder cancer elevates PD-L1 protein levels by affecting its ubiquitination, thereby inhibiting the antitumor activity of CD8+ T cells. Tissue microarray analysis in human UC showed an inverse correlation between FGFR3 and PD-L1. Furthermore, NEDD4, an E3 ubiquitin ligase of the NEDD4 family of proteins, was phosphorylated by FGFR3 activation and served as a regulator of PD-L1 ubiquitination. Mechanistically, NEDD4 interacted with PD-L1 and catalyzed Lys48 (K48)-linked polyubiquitination of PD-L1. In mice bearing NEDD4 knockout bladder cancer, CD8+ T-cell infiltration and antitumor activity were significantly inhibited due to PD-L1 upregulation in bladder cancer cells. Furthermore, multiple FGFR3-activated tumor-bearing mouse models suggested that attenuated CD8+ T-cell-mediated antitumor efficacy following FGFR3-targeted therapy could be rescued by a combination with anti-PD-1 immunotherapy, which leads to effective tumor suppression. This study establishes a key molecular link between targeted therapy and immune surveillance and identifies NEDD4 as a crucial E3 ubiquitin ligase that targets PD-L1 for degradation in FGFR3-activated bladder cancer. These findings may potentially be exploited for combination therapies in UC of the bladder and possibly other malignancies with activated FGFR3. SIGNIFICANCE: NEDD4 links two important molecules associated with targeted therapy and immune surveillance, providing mechanistic rationale and preclinical support for immuno-targeted combination therapy for FGFR3-activated bladder cancer.

Inhibiting Src-mediated PARP1 tyrosine phosphorylation confers synthetic lethality to PARP1 inhibition in HCC.

Hepatocellular carcinoma (HCC), a heterogeneous cancer with high mortality, is resistant to single targeted therapy; thus, combination therapy based on synthetic lethality is a promising therapeutic strategy for HCC. Poly (adenosine diphosphate [ADP]-ribose) polymerase 1 (PARP1) is the most recognized target for synthetic lethality; however, the therapeutic effect of PARP1 inhibition on HCC is disappointing. Therefore, exploring new synthetic lethal partners for the efficient manipulation of HCC is urgently required. In this study, we identified Src and PARP1 as novel synthetic lethal partners, and the combination therapy produced significant anti-tumor effects without causing obvious side effects. Mechanistically, Src interacted with PARP1 and phosphorylated PARP1 at the Y992 residue, which further mediated resistance to PARP1 inhibition. Overall, this study revealed that Src-mediated PARP1 phosphorylation induced HCC resistance to PARP1 inhibitors and indicated a therapeutic window of the Y992 phosphorylation of PARP1 for HCC patients. Moreover, synthetic lethal therapy by co-targeting PARP1 and Src have the potential to broaden the strategies for HCC and might benefit HCC patients with high Src activation and resistance to PARP1 inhibitors alone.

Neutrophil Elastase Induces Chondrocyte Apoptosis and Facilitates the Occurrence of Osteoarthritis via Caspase Signaling Pathway.

Osteoarthritis (OA) is the most common and prevalent chronic joint disorders in the elderly population across the globe, resulting in severe disability and impairment of quality of life. Existing treatment can only alleviate the symptoms and delay the progression of OA. Therefore, novel and effective therapeutics strategies for OA need to be developed. Our present study first found that neutrophil elastase (NE) was significantly increased in OA patients' synovial fluid. Next, we examined the effect of neutrophil elastase (NE) on chondrocytes in vitro and in vivo. The results showed that NE suppressed cell proliferation, induced apoptosis and prevented cell migration in chondrocytes in vitro, accompanied by the elevation of intracellular ROS and calcium level. Moreover, NE enhanced the cleaved caspase-3 levels and disrupted the mitochondrial transmembrane potential balance. Meanwhile, chondrocytes apoptosis induced by NE can be alleviated by caspase inhibitor, zVAD-FMK and antioxidants, GSH. Besides, treatment of sivelestat, the inhibitor of NE, significantly reduced the pathological processes in OA model rats in vivo. The results of our study suggested that NE is an important factor in OA, which induces chondrocyte apoptosis and facilitates the occurrence of OA via caspase signaling pathway, and targeting the crucial signal centering around NE may be the potential therapies for OA.

Anticancer Properties and Mechanisms of Singly-Protonated Dehydronorcantharidin Silver Coordination Polymer in a Bladder Cancer Model.

Bladder cancer is the most common malignant urinary system tumor. Chemotherapy is frequently used as a treatment regimen for patients with bladder cancer, however, new and effective drugs for bladder cancer need to be developed. The present study examined the effects and mechanisms of Ag-SP-DNC, a silver and singly-protonated dehydronorcantharidin complex, on bladder cancer in vitro and in vivo. It was identified that Ag-SP-DNC suppressed cell proliferation and induced apoptosis in bladder cancer cells in vitro, a suppression associated with G0/G1 phase arrest and elevated intracellular reactive oxygen species (ROS) levels. Furthermore, Ag-SP-DNC enhanced the cleaved caspase-3 levels, disrupted the mitochondrial transmembrane potential balance, and induced intracellular calcium overload. The Ag-SP-DNC-induced bladder cancer cell apoptosis was significantly decreased following treatment with a broad caspase inhibitor, zVAD-fmk. In addition, treatment of MB49 tumor-bearing mice with Ag-SP-DNC significantly inhibited tumor growth and decreased the anti-apoptosis and cell cycle promotion protein levels in the tumor. The results of the present study suggested that Ag-SP-DNC elicits a strong anticancer effect against bladder cancer, and can therefore be used as a promising treatment for bladder cancer.

Arginine methyltransferase PRMT5 negatively regulates cGAS-mediated antiviral immune response.

Cyclic GMP-AMP synthase (cGAS) functions as an essential DNA sensor, which senses the cytoplasmic double-stranded DNA and activates the antiviral response. However, the posttranslational modification of cGAS remains to be fully understood and whether it has arginine methylation modification remains unknown. Here, we identified protein arginine methyltransferase 5 (PRMT5) as a direct binding partner of cGAS, and it catalyzed the arginine symmetrical dimethylation of cGAS at the Arg124 residue. Further investigation demonstrated that methylation of cGAS by PRMT5 attenuated cGAS-mediated antiviral immune response by blocking the DNA binding ability of cGAS. Oral administration of PRMT5 inhibitors significantly protected mice from HSV-1 infection and prolonged the survival time of these infected mice. Therefore, our findings revealed an essential regulatory effect of PRMT5 on cGAS-mediated antiviral immune response and provided a promising potential antiviral strategy by modulating PRMT5.

Immunostimulant hydrogel for the inhibition of malignant glioma relapse post-resection.

Immunotherapies have revolutionized intervention strategies for many primary cancers, but have not improved the outcomes of glioblastoma multiforme (GBM), which remains one of the most lethal malignant cerebral tumours. Here we present an injectable hydrogel system that stimulates tumoricidal immunity after GBM surgical resection, which mitigates its relapse. The hydrogel comprises a tumour-homing immune nanoregulator, which induces immunogenic cell death and suppression of indoleamine 2,3-dioxygenase-1, and chemotactic CXC chemokine ligand 10, for a sustained T-cell infiltration. When delivered in the resected tumour cavity, the hydrogel system mimics a 'hot' tumour-immunity niche for attacking residual tumour cells and significantly suppresses postoperative GBM recurrence. Our work provides an alternative strategy for conferring effective tumoricidal immunity in GBM patients, which may have a broad impact in the immunotherapy of 'cold' tumours after surgical intervention.

Rational design and synthesis of 6-aryl-6H-benzo[c]chromenes as non-steroidal progesterone receptor antagonists for use against cancers.

Progesterone receptor (PR) antagonists have been found to be effective for treating certain human cancers. However, the steroidal structure of PR antagonists could bind to other hormone receptors, thus leading to serious side effects. On the other hand, non-steroidal PR antagonists have rarely been evaluated for their anti-cancer efficacy. Therefore, identifying novel non-steroidal PR antagonists possessing potent anti-cancer efficacy would be an attractive project to pursue. In this study, we presented a new metal-free oxidative CH arylation method to rapidly synthesize a series of 6-aryl-6H-benzo[c]chromene derivatives. Multiple cancer cell lines were used for their anti-cancer activity screening. An extensive analysis of structure-activity relationships (SAR) of the derivatives revealed that compounds 32 and 34 markedly inhibited the proliferation of MCF-7 cells with IC50 values of 6.32 ± 0.52 µM and 5.71 ± 0.49 µM, respectively. Further investigation indicated that derivatives 32 and 34 could elevate the expression of p21 and decrease the expressions of CDK4 and cyclin D1, leading to cell cycle arrest at G0/G1 phase. In addition, derivatives 32 and 34 could induce apoptosis of MCF-7 cells in both dose- and time-dependent manners by activation of p53 pathway, i.e., activation of Cleaved Caspase-3, p53 and P-p53 as well as elevation of the Bax/Bcl-2 ratio. Docking of derivatives 32 and 34 into a PR homology model exhibited potent PR antagonistic activity indicating the 6-aryl-6H-benzo[c]chromene derivatives are promising PR antagonists. We envisioned that derivatives 32 and 34 might be potential anti-cancer drug candidates as novel therapeutic treatment for breast cancer.

Krill Oil Perturbs Proliferation and Migration of Mouse Colon Cancer Cells in vitro by Impeding Extracellular Signal-Regulated Protein Kinase Signaling Pathway.

The prevalence of colorectal cancer (CRC) continues to increase. Treatment of CRC remains a significant clinical challenge, and effective therapies for advanced CRC are desperately needed. Increasing attention and ongoing research efforts have focused on krill oil that may provide health benefits to the human body. Here we report that krill oil exerts in vitro anticancer activity through a direct inhibition on proliferation, colony formation, migration, and invasion of mouse colon cancer cells. Krill oil inhibited the proliferation and colony formation of CT-26 colon cancer cells by causing G0/G1 cell cycle arrest and apoptosis. Cell cycle arrest was attributable to reduction of cyclin D1 levels in krill oil-treated cells. Further studies revealed that krill oil induced mitochondrial-dependent apoptosis of CT-26 cells, including loss of mitochondrial membrane potential, increased cytosolic calcium levels, activation of caspase-3, and downregulation of anti-apoptotic proteins MCL-1 and BCL-XL. Krill oil suppressed migration of CT-26 cells by disrupting the microfilaments and microtubules. Extracellular signal-regulated protein kinase (ERK) plays crucial roles in regulating proliferation and migration of cancer cells. We found that krill oil attenuated the activation of ERK signaling pathway to exert the effects on cell cycle, apoptosis, and migration of colon cancer cells. We speculate that polyunsaturated fatty acids of krill oil may dampen ERK activation by decreasing the phospholipid saturation of cell membrane. Although findings from in vitro studies may not necessarily translate in vivo, our study provides insights into the possibility that krill oil or its components could have therapeutic potential in colon cancer.

Design, synthesis and biological evaluation of novel 1,3,4,9-tetrahydropyrano[3,4-b]indoles as potential treatment of triple negative breast cancer by suppressing PI3K/AKT/mTOR pathway.

Triple-negative breast cancer (TNBC) represents a subset of breast cancer characterized by high aggressiveness and poor prognosis. Currently, there is no curative therapeutic regimen for TNBC patients. In this study, molecular hybridization strategy is adopted by combining benzopyran and indole pharmacophores together, and a library of structurally simple 1,3,4,9-tetrahydropyrano[3,4-b]indoles was rapidly constructed. The structure-activity relationship studies indicated that compound 23 exhibited the most potent effect against the MDA-MB-231 cells with IC50 value of 2.29 µM. Mechanistic studies revealed that compound 23 inhibited cell proliferation via arresting cell cycle at G0/G1 phase. It induced cell apoptosis by disruption of mitochondrial membrane potential (MMP), accumulation of reactive oxygen species (ROS), reduction of glutathione (GSH), elevation of intracellular calcium ion (Ca2+) and activation of caspase cascade. Furthermore, compound 23 significantly inhibited the regulators of PI3K/AKT/mTOR pathway in MDA-MB-231 cells, suggesting that PI3K/AKT/mTOR pathway was involved in the 23-mediated apoptosis. To our knowledge, this is the first example of the anti-cancer activity study of indole-fused pyrans through suppressing PI3K/AKT/mTOR pathway. Overall, the current study suggested that compound 23 would serve as a promising lead compound for TNBC treatment.