MUC1-C Integrates Chromatin Remodeling and PARP1 Activity in the DNA Damage Response of Triple-Negative Breast Cancer Cells

MUC1-C regulates NEAT1 lncRNA expression and paraspeckle formation in cancer progression

The MUC1 gene evolved in mammals for adaptation of barrier tissues in response to infections and damage. Paraspeckles are nuclear bodies formed on the NEAT1 lncRNA in response to loss of homeostasis. There is no known intersection of MUC1 with NEAT1 or paraspeckles. Here, we demonstrate that the MUC1-C subunit plays an essential role in regulating NEAT1 expression. MUC1-C activates the NEAT1 gene with induction of the NEAT1_1 and NEAT1_2 isoforms by NF-κB- and MYC-mediated mechanisms. MUC1-C/MYC signaling also induces expression of the SFPQ, NONO and FUS RNA binding proteins (RBPs) that associate with NEAT1_2 and are necessary for paraspeckle formation. MUC1-C integrates activation of NEAT1 and RBP-encoding genes by recruiting the PBAF chromatin remodeling complex and increasing chromatin accessibility of their respective regulatory regions. We further demonstrate that MUC1-C and NEAT1 form an auto-inductive pathway that drives common sets of genes conferring responses to inflammation and loss of homeostasis. Of functional significance, we find that the MUC1-C/NEAT1 pathway is of importance for the cancer stem cell (CSC) state and anti-cancer drug resistance. These findings identify a previously unrecognized role for MUC1-C in the regulation of NEAT1, RBPs, and paraspeckles that has been co-opted in promoting cancer progression.

Mutational profile evaluates metastatic capacity of Chinese colorectal cancer patients, revealed by whole-exome sequencing

Colorectal cancer (CRC) is the third most common cancer and the prevalence rate of CRC is increasing in the China. In this study, whole-exome sequencing (WES) was performed on primary tissues of 47 CRC Chinese patients including 22 metastatic and 25 non-metastatic patients. By comparison with data from western colorectal cancer patients in the Cancer Genome Atlas (TCGA), we identified a number of genes that are more likely to be mutated in Chinese colorectal cancer patients, such as MUC12, MUC12, MUC2, MUC4, HYDIN and KMT2C. Interestingly, MUC family genes including MUC12, MUC2 and MUC4, have mutation rates of >20%, while the mutation frequency was extremely low in western colorectal cancer patients, which were <3% in TCGA and 0% in Memorial Sloan Kettering Cancer Center (MSKCC). We detected metastasis-specific mutated genes including TCF7L2, MST1L, HRNR and SMAD4, while MUC4, NEB, FLG and RFPL4A alteration is more prevalent in the non-metastasis group. Further analysis reveals mutation genes in metastasis group are more focus in the Wnt and Hippo signaling pathway. APC, SMAD4 and TCF7L2 accounted for the major genetic abnormalities in this pathway. In conclusion, this study identified the unique characteristics of gene mutations in Chinese patients with colorectal cancer, and is a valuable reference for personalized treatment in Chinese CRC patients.

Advances in MUC1 resistance to chemotherapy in pancreatic cancer

The incidence of pancreatic cancer (PC), a highly fatal malignancy, is increasing every year. Chemotherapy is an important treatment for it in addition to surgery, yet most patients become resistant to chemotherapeutic agents within a few weeks of treatment initiation.​ MUC1 is a highly glycosylated transmembrane protein, and studies have shown that aberrantly glycosylated overexpression of MUC1 is involved in regulating the biology of chemoresistance in cancer cells. This article summarizes the mechanism of MUC1 in PC chemoresistance and reviews MUC1-based targeted therapies.

The multifaceted role of MUC1 in tumor therapy resistance

Tumor therapeutic resistances are frequently linked to the recurrence and poor prognosis of cancers and have been a key bottleneck in clinical tumor treatment. Mucin1 (MUC1), a heterodimeric transmembrane glycoprotein, exhibits abnormally overexpression in a variety of human tumors and has been confirmed to be related to the formation of therapeutic resistance. In this review, the multifaceted roles of MUC1 in tumor therapy resistance are summarized from aspects of pan-cancer principles shared among therapies and individual mechanisms dependent on different therapies. Concretely, the common mechanisms of therapy resistance across cancers include interfering with gene expression, promoting genome instability, modifying tumor microenvironment, enhancing cancer heterogeneity and stemness, and activating evasion and metastasis. Moreover, the individual mechanisms of therapy resistance in chemotherapy, radiotherapy, and biotherapy are introduced. Last but not least, MUC1-involved therapy resistance in different types of cancers and MUC1-related clinical trials are summarized.

Triumphs and challenges in exploiting poly(ADP-ribose) polymerase inhibition to combat triple-negative breast cancer

Poly(ADP-ribose) polymerase 1 (PARP1) regulates a myriad of DNA repair mechanisms to preserve genomic integrity following DNA damage. PARP inhibitors (PARPi) confer synthetic lethality in malignancies with a deficiency in the homologous recombination (HR) pathway. Patients with triple-negative breast cancer (TNBC) fail to respond to most targeted therapies because their tumors lack expression of the estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Certain patients with TNBC harbor mutations in HR mediators such as breast cancer susceptibility gene 1 (BRCA1) and breast cancer susceptibility gene 2 (BRCA2), enabling them to respond to PARPi. PARPi exploits the synthetic lethality of BRCA-mutant cells. However, de novo and acquired PARPi resistance frequently ensue. In this review, we discuss the roles of PARP in mediating DNA repair processes in breast epithelial cells, mechanisms of PARPi resistance in TNBC, and recent advances in the development of agents designed to overcome PARPi resistance in TNBC.

Farrerol directly activates the deubiqutinase UCHL3 to promote DNA repair and reprogramming when mediated by somatic cell nuclear transfer

Farrerol, a natural flavanone, promotes homologous recombination (HR) repair to improve genome-editing efficiency, but the specific protein that farrerol directly targets to regulate HR repair and the underlying molecular mechanisms have not been determined. Here, we find that the deubiquitinase UCHL3 is the direct target of farrerol. Mechanistically, farrerol enhanced the deubiquitinase activity of UCHL3 to promote RAD51 deubiquitination, thereby improving HR repair. Importantly, we find that embryos of somatic cell nuclear transfer (SCNT) exhibited defective HR repair, increased genomic instability and aneuploidy, and that the farrerol treatment post nuclear transfer enhances HR repair, restores transcriptional and epigenetic network, and promotes SCNT embryo development. Ablating UCHL3 significantly attenuates farrerol-mediated stimulation in HR and SCNT embryo development. In summary, we identify farrerol as an activator of the deubiquitinase UCHL3, highlighted the importance of HR and epigenetic changes in SCNT reprogramming and provide a feasible method to promote SCNT efficiency.

MUC1-C Dictates PBRM1-Mediated Chronic Induction of Interferon Signaling, DNA Damage Resistance, and Immunosuppression in Triple-Negative Breast Cancer

The polybromo-1 (PBRM1) chromatin-targeting subunit of the SWI/SNF PBAF chromatin remodeling complex drives DNA damage resistance and immune evasion in certain cancer cells through mechanisms that remain unclear. STAT1 and IRF1 are essential effectors of type I and II IFN pathways. Here, we report that MUC1-C is necessary for PBRM1 expression and that it forms a nuclear complex with PBRM1 in triple-negative breast cancer (TNBC) cells. Analysis of global transcriptional (RNA-seq) and chromatin accessibility (ATAC-seq) profiles further demonstrated that MUC1-C and PBRM1 drive STAT1 and IRF1 expression by increasing chromatin accessibility of promoter-like signatures (PLS) on their respective genes. We also found that MUC1-C, PBRM1, and IRF1 increase the expression and chromatin accessibility on PLSs of the (i) type II IFN pathway IDO1 and WARS genes and (ii) type I IFN pathway RIG-I, MDA5, and ISG15 genes that collectively contribute to DNA damage resistance and immune evasion. In support of these results, targeting MUC1-C in wild-type BRCA TNBC cells enhanced carboplatin-induced DNA damage and the loss of self-renewal capacity. In addition, MUC1-C was necessary for DNA damage resistance, self-renewal, and tumorigenicity in olaparib-resistant BRCA1-mutant TNBC cells. Analysis of TNBC tumors corroborated that (i) MUC1 and PBRM1 are associated with decreased responsiveness to chemotherapy and (ii) MUC1-C expression is associated with the depletion of tumor-infiltrating lymphocytes (TIL). These findings demonstrate that MUC1-C activates PBRM1, and thereby chromatin remodeling of IFN-stimulated genes that promote chronic inflammation, DNA damage resistance, and immune evasion.

IMPLICATIONS

MUC1-C is necessary for PBRM1-driven chromatin remodeling in chronic activation of IFN pathway genes that promote DNA damage resistance and immunosuppression.

MUC1 Tissue Expression and Its Soluble Form CA15-3 Identify a Clear Cell Renal Cell Carcinoma with Distinct Metabolic Profile and Poor Clinical Outcome

An altered metabolism is involved in the development of clear cell renal carcinoma (ccRCC). MUC1 overexpression has been found to be associated with advanced disease and poor prognosis. In this study, we evaluated the metabolomic profile of human ccRCC, according to MUC1 expression, and integrated it with transcriptomic data. Moreover, we analyzed the role of MUC1 in sustaining ccRCC aggressiveness and the prognostic value of its soluble form CA15-3. Integrated metabolomic and transcriptomic analysis showed that MUC1-expressing ccRCC was characterized by metabolic reprogramming involving the glucose and lipid metabolism pathway. In addition, primary renal cancer cells treated with a small interfering RNA targeting MUC1 (siMUC1) migrated and proliferated at a slower rate than untreated cancer cells. After cisplatin treatment, the death rate of cancer cells treated with siMUC1 was significantly greater than that of untreated cells. Kaplan-Meier curves showed significant differences in CSS and PFS among groups of patients with high versus low levels of CA15-3. In a multivariate analysis, CA15-3 was an independent adverse prognostic factor for cancer-specific and progression-free survival. In conclusion, MUC1 expressing ccRCC is characterized by a particular metabolic reprogramming. The inhibition of MUC1 expression decreases cell motility and viability and improves cisplatin susceptibility, suggesting that this pathway can regulate de novo chemotherapy resistance in ccRCC.

The oncoprotein MUC1 facilitates breast cancer progression by promoting Pink1-dependent mitophagy via ATAD3A destabilization

Mitophagy is a vital process that controls mitochondria quality, dysregulation of which can promote cancer. Oncoprotein mucin 1 (MUC1) targets mitochondria to attenuate drug-induced apoptosis. However, little is known about whether and how MUC1 contributes to mitochondrial homeostasis in cancer cells. We identified a novel role of MUC1 in promoting mitophagy. Increased mitophagy is coupled with the translocation of MUC1 to mitochondria, where MUC1 interacts with and induces degradation of ATPase family AAA domain-containing 3A (ATAD3A), resulting in protection of PTEN-induced kinase 1 (Pink1) from ATAD3A-mediated cleavage. Interestingly, MUC1-induced mitophagy is associated with increased oncogenicity of cancer cells. Similarly, inhibition of mitophagy significantly suppresses MUC1-induced cancer cell activity in vitro and in vivo. Consistently, MUC1 and ATAD3A protein levels present an inverse relationship in tumor tissues of breast cancer patients. Our data validate that MUC1/ATAD3A/Pink1 axis-mediated mitophagy constitutes a novel mechanism for maintaining the malignancy of cancer cells, providing a novel therapeutic approach for MUC1-positive cancers.

Combined inhibition of PARP and EZH2 for cancer treatment: Current status, opportunities, and challenges

Tumors with BRCA1/2 mutations or homologous recombination repair defects are sensitive to PARP inhibitors through the mechanism of synthetic lethality. Several PARP inhibitors are currently approved for ovarian, breast and pancreatic cancer in clinical practice. However, more than 40% of patients with BRCA1/2 mutations are insensitive to PARP inhibitors, which has aroused attention to the mechanism of PARP resistance and sensitization schemes. PARP inhibitor resistance is related to homologous recombination repair, stability of DNA replication forks, PARylation and epigenetic modification. Studies on epigenetics have become the hotspots of research on PARP inhibitor resistance. As an important epigenetic regulator of transcription mediated by histone methylation, EZH2 interacts with PARP through DNA homologous recombination, DNA replication, posttranslational modification, tumor immunity and other aspects. EZH2 inhibitors have been just shifting from the bench to the bedside, but the combination scheme in cancer therapy has not been fully explored yet. Recently, a revolutionary drug design combining PARP inhibitors and EZH2 inhibitors based on PROTAC techniques has shed light on the resolution of PARP inhibitor resistance. This review summarizes the interactions between EZH2 and PARP, suggests the potential PARP inhibitor sensitization effect of EZH2 inhibitors, and further discusses the potential populations that benefit from the combination of EZH2 inhibitors and PARP inhibitors.

Emergence of MUC1 in Mammals for Adaptation of Barrier Epithelia

The mucin 1 (MUC1) gene was discovered based on its overexpression in human breast cancers. Subsequent work demonstrated that MUC1 is aberrantly expressed in cancers originating from other diverse organs, including skin and immune cells. These findings supported a role for MUC1 in the adaptation of barrier tissues to infection and environmental stress. Of fundamental importance for this evolutionary adaptation was inclusion of a SEA domain, which catalyzes autoproteolysis of the MUC1 protein and formation of a non-covalent heterodimeric complex. The resulting MUC1 heterodimer is poised at the apical cell membrane to respond to loss of homeostasis. Disruption of the complex releases the MUC1 N-terminal (MUC1-N) subunit into a protective mucous gel. Conversely, the transmembrane C-terminal (MUC1-C) subunit activates a program of lineage plasticity, epigenetic reprogramming and repair. This MUC1-C-activated program apparently evolved for barrier tissues to mount self-regulating proliferative, inflammatory and remodeling responses associated with wound healing. Emerging evidence indicates that MUC1-C underpins inflammatory adaptation of tissue stem cells and immune cells in the barrier niche. This review focuses on how prolonged activation of MUC1-C by chronic inflammation in these niches promotes the cancer stem cell (CSC) state by establishing auto-inductive nodes that drive self-renewal and tumorigenicity.

Dependence on the MUC1-C Oncoprotein in Classic, Variant, and Non-neuroendocrine Small Cell Lung Cancer

Small cell lung cancer (SCLC) is a recalcitrant malignancy defined by subtypes on the basis of differential expression of the ASCL1, NEUROD1, and POU2F3 transcription factors. The MUC1-C protein is activated in pulmonary epithelial cells by exposure to environmental carcinogens and promotes oncogenesis; however, there is no known association between MUC1-C and SCLC. We report that MUC1-C is expressed in classic neuroendocrine (NE) SCLC-A, variant NE SCLC-N and non-NE SCLC-P cells and activates the MYC pathway in these subtypes. In SCLC cells characterized by NE differentiation and DNA replication stress, we show that MUC1-C activates the MYC pathway in association with induction of E2F target genes and dysregulation of mitotic progression. Our studies further demonstrate that the MUC1-C→MYC pathway is necessary for induction of (i) NOTCH2, a marker of pulmonary NE stem cells that are the proposed cell of SCLC origin, and (ii) ASCL1 and NEUROD1. We also show that the MUC1-C→MYC→NOTCH2 network is necessary for self-renewal capacity and tumorigenicity of NE and non-NE SCLC cells. Analyses of datasets from SCLC tumors confirmed that MUC1 expression in single SCLC cells significantly associates with activation of the MYC pathway. These findings demonstrate that SCLC cells are addicted to MUC1-C and identify a potential new target for SCLC treatment.

IMPLICATIONS

This work uncovers addiction of SCLC cells to MUC1-C, which is a druggable target that could provide new opportunities for advancing SCLC treatment.

Addiction of Cancer Stem Cells to MUC1-C in Triple-Negative Breast Cancer Progression

Triple-negative breast cancer (TNBC) is an aggressive malignancy with limited treatment options. TNBC progression is associated with expansion of cancer stem cells (CSCs). Few insights are available regarding druggable targets that drive the TNBC CSC state. This review summarizes the literature on TNBC CSCs and the compelling evidence that they are addicted to the MUC1-C transmembrane protein. In normal epithelia, MUC1-C is activated by loss of homeostasis and induces reversible wound-healing responses of inflammation and repair. However, in settings of chronic inflammation, MUC1-C promotes carcinogenesis. MUC1-C induces EMT, epigenetic reprogramming and chromatin remodeling in TNBC CSCs, which are dependent on MUC1-C for self-renewal and tumorigenicity. MUC1-C-induced lineage plasticity in TNBC CSCs confers DNA damage resistance and immune evasion by chronic activation of inflammatory pathways and global changes in chromatin architecture. Of therapeutic significance, an antibody generated against the MUC1-C extracellular domain has been advanced in a clinical trial of anti-MUC1-C CAR T cells and in IND-enabling studies for development as an antibody–drug conjugate (ADC). Agents targeting the MUC1-C cytoplasmic domain have also entered the clinic and are undergoing further development as candidates for advancing TNBC treatment. Eliminating TNBC CSCs will be necessary for curing this recalcitrant cancer and MUC1-C represents a promising druggable target for achieving that goal.

Addiction of Merkel cell carcinoma to MUC1-C identifies a potential new target for treatment

Merkel cell carcinoma (MCC) is an aggressive malignancy with neuroendocrine (NE) features, limited treatment options, and a lack of druggable targets. There is no reported involvement of the MUC1-C oncogenic protein in MCC progression. We show here that MUC1-C is broadly expressed in MCCs and at higher levels in Merkel cell polyomavirus (MCPyV)-positive (MCCP) relative to MCPyV-negative (MCCN) tumors. Our results further demonstrate that MUC1-C is expressed in MCCP, as well as MCCN, cell lines and regulates common sets of signaling pathways related to RNA synthesis, processing, and transport in both subtypes. Mechanistically, MUC1-C (i) interacts with MYCL, which drives MCC progression, (ii) is necessary for expression of the OCT4, SOX2, KLF4, MYC, and NANOG pluripotency factors, and (iii) induces the NEUROD1, BRN2 and ATOH1 NE lineage dictating transcription factors. We show that MUC1-C is also necessary for MCCP and MCCN cell survival by suppressing DNA replication stress, the p53 pathway, and apoptosis. In concert with these results, targeting MUC1-C genetically and pharmacologically inhibits MCC self-renewal capacity and tumorigenicity. These findings demonstrate that MCCP and MCCN cells are addicted to MUC1-C and identify MUC1-C as a potential target for MCC treatment.

Targeting MUC1-C Suppresses Chronic Activation of Cytosolic Nucleotide Receptors and STING in Triple-Negative Breast Cancer

Simple Summary

Triple-negative breast cancers (TNBCs) are recalcitrant tumors with limited therapeutic options. Cytotoxic agents, including platinum-based drugs, are a standard of care for advanced TNBCs. Olaparib is also used for the treatment of germline BRCA mutant TNBC tumors in the adjuvant and recurrent disease settings. Notably, however, the effectiveness of these genotoxic agents is often limited by intrinsic and adaptive DNA damage resistance. We demonstrate in TNBC cells that the oncogenic MUC1-C protein chronically activates the type I interferon (IFN) pathway, drives the cGAS/STING axis and induces expression of the DNA damage resistance gene signature (IRDS). Targeting MUC1-C inhibits activation of this pathway in the response to carboplatin and olaparib and sensitizes TNBC cells to these agents. These findings indicate that MUC1-C is a target, which is druggable, for overcoming the obstacle of DNA damage resistance in the treatment of TNBCs.

Abstract

The MUC1-C apical transmembrane protein is activated in the acute response of epithelial cells to inflammation. However, chronic MUC1-C activation promotes cancer progression, emphasizing the importance of MUC1-C as a target for treatment. We report here that MUC1-C is necessary for intrinsic expression of the RIG-I, MDA5 and cGAS cytosolic nucleotide pattern recognition receptors (PRRs) and the cGAS-stimulator of IFN genes (STING) in triple-negative breast cancer (TNBC) cells. Consistent with inducing the PRR/STING axis, MUC1-C drives chronic IFN-β production and activation of the type I interferon (IFN) pathway. MUC1-C thereby induces the IFN-related DNA damage resistance gene signature (IRDS), which includes ISG15, in linking chronic inflammation with DNA damage resistance. Targeting MUC1-C in TNBC cells treated with carboplatin or the PARP inhibitor olaparib further demonstrated that MUC1-C is necessary for expression of PRRs, STING and ISG15 and for intrinsic DNA damage resistance. Of translational relevance, MUC1 significantly associates with upregulation of STING and ISG15 in TNBC tumors and is a target for treatment with CAR T cells, antibody–drug conjugates (ADCs) and direct inhibitors that are under preclinical and clinical development.

KLF5 inhibition overcomes oxaliplatin resistance in patient-derived colorectal cancer organoids by restoring apoptotic response

Oxaliplatin resistance is a major challenge in the treatment of colorectal cancer (CRC). Many molecular targeted drugs for refractory CRC have been developed to solve CRC drug resistance, but their effectiveness and roles in the progression of CRC and oxaliplatin resistance remain unclear. Here, we successfully constructed CRC PDOs and selected the Kruppel-like factor 5 (KLF5) inhibitor ML264 as the research object based on the results of the in vitro drug screening assay. ML264 significantly restored oxaliplatin sensitivity in CRC PDOs by restoring the apoptotic response, and this effect was achieved by inhibiting the KLF5/Bcl-2/caspase3 signaling pathway. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays verified that KLF5 promoted the transcription of Bcl-2 in CRC cells. KLF5 inhibition also overcame oxaliplatin resistance in xenograft tumors. Taken together, our study demonstrated that ML264 can restore oxaliplatin sensitivity in CRC PDOs by restoring the apoptotic response. KLF5 may be a potential therapeutic target for oxaliplatin-resistant CRC. PDOs have a strong potential for evaluating inhibitors and drug combination therapy in a preclinical environment.

The expanding universe of PARP1-mediated molecular and therapeutic mechanisms

ADP-ribosylation (ADPRylation) is a post-translational modification of proteins catalyzed by ADP-ribosyl transferase (ART) enzymes, including nuclear PARPs (e.g., PARP1 and PARP2). Historically, studies of ADPRylation and PARPs have focused on DNA damage responses in cancers, but more recent studies elucidate diverse roles in a broader array of biological processes. Here, we summarize the expanding array of molecular mechanisms underlying the biological functions of nuclear PARPs with a focus on PARP1, the founding member of the family. This includes roles in DNA repair, chromatin regulation, gene expression, ribosome biogenesis, and RNA biology. We also present new concepts in PARP1-dependent regulation, including PAR-dependent post-translational modifications, "ADPR spray," and PAR-mediated biomolecular condensate formation. Moreover, we review advances in the therapeutic mechanisms of PARP inhibitors (PARPi) as well as the progress on the mechanisms of PARPi resistance. Collectively, the recent progress in the field has yielded new insights into the expanding universe of PARP1-mediated molecular and therapeutic mechanisms in a variety of biological processes.

MS275 as Class I HDAC inhibitor displayed therapeutic potential on malignant ascites by iTRAQ-based quantitative proteomic analysis

Background

Malignant ascites is a manifestation of end stage events in a variety of cancers and is associated with significant morbidity. Epigenetic modulators play a key role in cancer initiation and progression, among which histone deacetylases (HDACs) are considered as one of the most important regulators for various cancer development, such as liver cancer, ovarian cancer, and pancreatic cancer et al. Thus, in this paper, we sought to explore the therapeutic effect of HDAC inhibitor on malignant ascites.

Methods

In this report, we tested the therapeutic effect of different isoform selective HDAC inhibitors (Class I HDACI MS275, Class IIa HDACI MC1568, pan-HDAC inhibitors SAHA) on malignant ascites in vitro and in vivo. We further used proteome analysis to find the potential mechanisms for malignant ascites therapy.

Results

Among the different isoform-selective HDAC inhibitors, the class I selective HDACI, MS275, exhibited preferential inhibition on various ascites cells. MS275 could induce cell cycle arrest in G0/G1 phase and promote apoptosis on ascites cells. Through proteome analysis, we found MS275 could downregulate proteins related to cell cycle progression, such as CDK4, CDC20, CCND1; MS275 could upregulate pro-apoptosis proteins such as PAPR1, LMNB2 and AIFM1; in addition, MS275 could change the expression of tumorigenic proteins related to the specific malignant ascites bearing tumors, such as TSP1 and CDK4 for bladder cancer. We then confirmed that abemaciclib (CDK4/6 selective inhibitor) could inhibit the proliferation of ascites cells, and the combination of abemaciclib and MS275 had synergistic anti-tumor effect. Finally, we found that MS275 could in vivo inhibit malignant ascites progression (ascites volume: 2.9 ± 1.0 mL vs 7.5 ± 1.2 mL, p < 0.01), tumor growth, and prolong 66% of the life-span when compared with the untreated group.

Conclusion

This present research revealed that the class I selective HDAC inhibitor, MS275, could effectively inhibit malignant ascites development and tumor growth via multiple pathways. These results indicated that HDACI could have great potential for clinical therapy of malignant ascites.

Efficient Gene Knockout and Knockdown Systems in Neospora caninum Enable Rapid Discovery and Functional Assessment of Novel Proteins

The development of molecular genetics has greatly enhanced the study of the biology and pathology associated with parasites of the phylum Apicomplexa. While the molecular tools are highly developed for the apicomplexan Toxoplasma gondii, the closely related parasite Neospora caninum lacks efficient tools for genetic manipulation. To enable efficient homologous recombination in N. caninum, we targeted the Ku heterodimer DNA repair mechanism in the genomic reference strain, Nc-Liverpool (NcLiv), and show that deletion of Ku80 results in a destabilization and loss of its partner Ku70. Disruption of Ku80 generated parasites in which genes are efficiently epitope tagged and only short homology regions are required for gene knockouts. We used this improved strain to target novel nonessential genes encoding dense granule proteins that are unique to N. caninum or conserved in T. gondii. To expand the utility of this strain for essential genes, we developed the auxin-inducible degron system for N. caninum using parasite-specific promoters. As a proof of concept, we knocked down a novel nuclear factor in both N. caninum and T. gondii and showed that it is essential for survival of both parasites. Together, these efficient knockout and knockdown technologies will enable the field to unravel specific gene functions in N. caninum, which is likely to aid in the identification of targets responsible for the phenotypic differences observed between these two closely related apicomplexan parasites.

IMPORTANCENeospora caninum is a parasite with veterinary relevance, inducing severe disease in dogs and reproductive disorders in ruminants, especially cattle, leading to major losses. The close phylogenetic relationship to Toxoplasma gondii and the lack of pathogenicity in humans drives an interest of the scientific community toward using N. caninum as a model to study the pathogenicity of T. gondii. To enable this comparison, it is important to develop efficient molecular tools for N. caninum, to gain accuracy and save time in genetic manipulation protocols. Here, we have developed base strains and protocols using the genomic reference strain of N. caninum to enable efficient knockout and knockdown assays in this model. We demonstrate that these tools are effective in targeting known and previously unexplored genes. Thus, these tools will greatly improve the study of this protozoan, as well as enhance its ability to serve as a model to understand other apicomplexan parasites.

Mucin1 and Mucin16: Therapeutic Targets for Cancer Therapy

The mucin (MUC) family is a group of highly glycosylated macromolecules that are abundantly expressed in mammalian epithelial cells. MUC proteins contribute to the formation of the mucus barrier and thus have protective functions against infection. Interestingly, some MUC proteins are aberrantly expressed in cancer cells and are involved in cancer development and progression, including cell growth, proliferation, the inhibition of apoptosis, chemoresistance, metabolic reprogramming, and immune evasion. With their unique biological and structural features, MUC proteins have been considered promising therapeutic targets and also biomarkers for human cancer. In this review, we discuss the biological roles of the transmembrane mucins MUC1 and MUC16 in the context of hallmarks of cancer and current efforts to develop MUC1- and MUC16-targeted therapies.

PARP1-modulated chromatin remodeling is a new target for cancer treatment

Cancer progression requires certain tumorigenic mutations in genes encoding for different cellular and nuclear proteins. Altered expressions of these mutated genes are mediated by post-translational modifications and chromatin remodeling. Chromatin remodeling is mainly regulated by the chromatin remodeling enzyme complexes and histone modifications. Upon DNA damage, Poly-(ADP-ribose) Polymerase1 (PARP1) plays a very important role in the induction of chromatin modifications and activation of DNA repair pathways to repair the DNA lesion. It has been targeted to develop different anti-cancer therapeutic interventions and PARP inhibitors have been approved by the U.S. Food and Drug Administration (FDA) for clinical use. But it has been found that the cancer cells often develop resistance to these PARP inhibitors and chromatin remodeling helps in enhancing this process. Hence, it may be beneficial to target PARP1-mediated chromatin remodeling, which may allow to reverse the drug resistance. In the current review, we have discussed the role of chromatin remodeling in DNA repair, how PARP1 regulates modifications of chromatin dynamics, and the role of chromatin modifications in cancer. It has also been discussed how the PARP1-mediated chromatin remodeling can be targeted by PARP inhibitors alone or in combination with other chemotherapeutic agents to establish novel anti-cancer therapeutics. We have also considered the use of PARG inhibitors that may enhance the action of PARP inhibitors to target different types of cancers.

MUC1-C activates the PBAF chromatin remodeling complex in integrating redox balance with progression of human prostate cancer stem cells

The polybromo-associated PBAF (SWI/SNF) chromatin remodeling complex, which includes PBRM1, ARID2, and BRD7, regulates cell differentiation and genomic integrity. MUC1-C is an oncogenic protein that drives lineage plasticity in prostate cancer (PC) progression. The present work demonstrates that MUC1-C induces PBRM1, ARID2, and BRD7 expression by the previously unrecognized E2F1-mediated activation of their respective promoters. The functional significance of the MUC1-C→PBAF pathway is supported by demonstrating involvement of MUC1-C in associating with nuclear PBAF and driving the NRF2 antioxidant gene transcriptome in PC cells. Mechanistically, MUC1-C forms a complex with NRF2 and PBRM1 on the NRF2 target SLC7A11 gene that encodes the xCT cystine-glutamate antiporter, increases chromatin accessibility and induces SLC7A11/xCT expression. We also show that MUC1-C and PBRM1 are necessary for induction of other NRF2 target genes, including G6PD and PGD that regulate the pentose phosphate pathway. Our results further demonstrate that MUC1-C integrates activation of PBRM1 with the regulation of antioxidant genes, ROS levels, pluripotency factor expression and the cancer stem cell (CSC) state. These findings reveal a role for MUC1-C in regulating PBAF, redox balance and lineage plasticity of PC CSC progression. Our findings also uncover involvement of MUC1-C in integrating the PBAF and BAF pathways in cancer.

MUC1-C in chronic inflammation and carcinogenesis; emergence as a target for cancer treatment

Chronic inflammation is a highly prevalent consequence of changes in environmental and lifestyle factors that contribute to the development of cancer. The basis for this critical association has largely remained unclear. The MUC1 gene evolved in mammals to protect epithelia from the external environment. The MUC1-C subunit promotes responses found in wound healing and cancer. MUC1-C induces EMT, epigenetic reprogramming, dedifferentiation and pluripotency factor expression, which when prolonged in chronic inflammation promote cancer progression. As discussed in this review, MUC1-C also drives drug resistance and immune evasion, and is an important target for cancer therapeutics now under development.

Phosphatidylserine-exposing tumor-derived microparticles exacerbate coagulation and cancer cell transendothelial migration in triple-negative breast cancer

Background: Neoadjuvant chemotherapy is relevant to the formation of thromboembolism and secondary neoplasms in triple-negative breast cancer (TNBC). Chemotherapy-induced breast cancer cell-derived microparticles (BCMPs) may have important thrombogenic and pro-metastatic effects on platelets and endothelium, which may be related to the expression and distribution of phosphatidylserine (PS). However, investigating these interactions is challenging due to technical limitations.

Methods: A study was conducted in 20 healthy individuals and 18 patients who had been recently diagnosed with TNBC and were undergoing neoadjuvant chemotherapy with doxorubicin and cyclophosphamide. BCMPs were isolated from patient blood samples and doxorubicin-treated breast cancer cell lines. Their structure and morphology were studied by electron microscopy and antigen levels were measured by fluorescence-activated cell sorting. In an inhibition assay, isolated BCMPs were pretreated with lactadherin or tissue factor antibodies. Platelets isolated from healthy subjects were treated with BCMPs and coagulation time, fibrin formation, and expression of intrinsic/extrinsic factor Xase (FXa) and thrombin were evaluated. The effects of BCMPs on endothelial thrombogenicity and integrity were assessed by confocal microscopy, electron microscopy, measurement of intrinsic/extrinsic FXa, prothrombinase assay, and transwell permeability assay.

Results: Neoadjuvant chemotherapy significantly increased the expression of PS+ BCMPs in patient plasma. Its expression was associated with a rapid increase in procoagulant activity. Treatment with lactadherin, a PS-binding scavenging molecule, markedly reduced the adhesion of BCMPs and abolished their procoagulant activity, but this was not observed with tissue factor antibody treatment. Intravenous injection of BCMPs in mice induced a significant hypercoagulable state, reducing the extent of plasma fibrinogen and promoting the appearance of new thrombus. Cancer cells incubated with doxorubicin released large numbers of PS+ BCMPs, which stimulated and transformed endothelial cells into a procoagulant phenotype and increased the aggregation and activation of platelets. Moreover, cancer cells exploited this BCMP-induced endothelial leakiness and showed promoted metastasis. Pretreatment with lactadherin increased uptake of both PS+ BCMPs and cancer cells by endothelial cells and limited the transendothelial migration of cancer cells.

Conclusion: Lactadherin, a biosensor that we developed, was used to study the extracellular vesicle distribution of PS, which revealed a novel PS+ BCMPs administrative axis that initiated a local coagulation cascade and facilitated metastatic colonization of circulating cancer cells.

Evodiamine suppresses non-small cell lung cancer by elevating CD8+ T cells and downregulating the MUC1-C/PD-L1 axis

Background

Accumulating evidence showed that regulating tumor microenvironment plays a vital role in improving antitumor efficiency. Programmed Death Ligand 1 (PD-L1) is expressed in many cancer cell types, while its binding partner Programmed Death 1 (PD1) is expressed in activated T cells and antigen-presenting cells. Whereas, its dysregulation in the microenvironment is poorly understood. In the present study, we confirmed that evodiamine downregulates MUC1-C, resulting in modulating PD-L1 expression in non-small cell lung cancer (NSCLC).

Methods

Cell viability was measured by MTT assays. Apoptosis, cell cycle and surface PD-L1 expression on NSCLC cells were analyzed by flow cytometry. The expression of MUC1-C and PD-L1 mRNA was measured by real time RT-PCR methods. Protein expression was examined in evodiamine-treated NSCLC cells using immunoblotting or immunofluorescence assays. The effects of evodiamine treatment on NSCLC sensitivity towards T cells were investigated using human peripheral blood mononuclear cells and Jurkat, apoptosis and IL-2 secretion assays. Female H1975 xenograft nude mice were used to assess the effect of evodiamine on tumorigenesis in vivo. Lewis lung carcinoma model was used to investigate the therapeutic effects of combination evodiamine and anti-PD-1 treatment.

Results

We showed that evodiamine significantly inhibited growth, induced apoptosis and cell cycle arrest at G2 phase of NSCLC cells. Evodiamine suppressed IFN-γ-induced PD-L1 expression in H1975 and H1650. MUC1-C mRNA and protein expression were decreased by evodiamine in NSCLC cells as well. Evodiamine could downregulate the PD-L1 expression and diminish the apoptosis of T cells. It inhibited MUC1-C expression and potentiated CD8⁺ T cell effector function. Meanwhile, evodiamine showed good anti-tumor activity in H1975 tumor xenograft, which reduced tumor size. Evodiamine exhibited anti-tumor activity by elevation of CD8⁺ T cells in vivo in Lewis lung carcinoma model. Combination evodiamine and anti-PD-1 mAb treatment enhanced tumor growth control and survival of mice.

Conclusions

Evodiamine can suppress NSCLC by elevating of CD8⁺ T cells and downregulating of the MUC1-C/PD-L1 axis. Our findings uncover a novel mechanism of action of evodiamine and indicate that evodiamine represents a potential targeted agent suitable to be combined with immunotherapeutic approaches to treat NSCLC cancer patients. MUC1-C overexpression is common in female, non-smoker, patients with advanced-stage adenocarcinoma.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s13046-020-01741-5.

MUC1 oncoprotein mitigates ER stress via CDA-mediated reprogramming of pyrimidine metabolism

The Mucin 1 (MUC1) protein is overexpressed in various cancers and mediates chemotherapy resistance. However, the mechanism is not fully understood. Given that most chemotherapeutic drugs disrupt ER homeostasis as part of their toxicity, and MUC1 expression is regulated by proteins involved in ER homeostasis, we investigated the link between MUC1 and ER homeostasis. MUC1 knockdown in pancreatic cancer cells enhanced unfolded protein response (UPR) signaling and cell death upon ER stress induction. Transcriptomic analysis revealed alterations in the pyrimidine metabolic pathway and cytidine deaminase (CDA). ChIP and CDA activity assays showed that MUC1 occupied CDA gene promoter upon ER stress induction correlating with increased CDA expression and activity in MUC1-expressing cells as compared to MUC1 knockdown cells. Inhibition of either the CDA or pyrimidine metabolic pathway diminished survival in MUC1-expressing cancer cells upon ER stress induction. Metabolomic analysis demonstrated that MUC1-mediated CDA activity corresponded to deoxycytidine to deoxyuridine metabolic reprogramming upon ER stress induction. The resulting increase in deoxyuridine mitigated ER stress-induced cytotoxicity. Additionally, given 1) the established roles of MUC1 in protecting cells against reactive oxygen species (ROS) insults, 2) ER stress-generated ROS further promote ER stress and 3) the emerging anti-oxidant property of deoxyuridine, we further investigated if MUC1 regulated ER stress by a deoxyuridine-mediated modulation of ROS levels. We observed that deoxyuridine could abrogate ROS-induced ER stress to promote cancer cell survival. Taken together, our findings demonstrate a novel MUC1-CDA axis of the adaptive UPR that provides survival advantage upon ER stress induction.