USP7 promotes IgA class switching through stabilizing RUNX3 for germline transcription activation.

Class switch recombination (CSR) diversifies the effector functions of antibodies and involves complex regulation of transcription and DNA damage repair. Here, we show that the deubiquitinase USP7 promotes CSR to immunoglobulin A (IgA) and suppresses unscheduled IgG switching in mature B cells independent of its role in DNA damage repair, but through modulating switch region germline transcription. USP7 depletion impairs Sα transcription, leading to abnormal activation of Sγ germline transcription and increased interaction with the CSR center via loop extrusion for unscheduled IgG switching. Rescue of Sα transcription by transforming growth factor ß (TGF-ß) in USP7-deleted cells suppresses Sγ germline transcription and prevents loop extrusion toward IgG CSR. Mechanistically, USP7 protects transcription factor RUNX3 from ubiquitination-mediated degradation to promote Sα germline transcription. Our study provides evidence for active transcription serving as an anchor to impede loop extrusion and reveals a functional interplay between USP7 and TGF-ß signaling in promoting RUNX3 expression for efficient IgA CSR.

Enhancement of PRMT6 binding to a novel germline GATA1 mutation associated with congenital anemia.

Mutations in the master hematopoietic transcription factor GATA1 are often associated with functional defects in erythropoiesis and megakaryopoiesis. In this study, we identified a novel GATA1 germline mutation (c.1162delGG, p.Leu387Leufs*62) in a patient with congenital anemia and occasional thrombocytopenia. The C-terminal GATA1, a rarely studied mutational region, undergoes frameshifting translation as a consequence of this double-base deletion mutation. To investigate the specific function and pathogenic mechanism of this mutant, in vitro mutant models of stable re-expression cells were generated. The mutation was subsequently validated to cause diminished transcriptional activity of GATA1 and defective differentiation of erythroid and megakaryocytes. Using proximity labeling and mass spectrometry, we identified selective alterations in the proximal protein networks of the mutant, revealing decreased binding to a set of normal GATA1-interaction proteins, including the essential co-factor FOG1. Notably, our findings further demonstrated enhanced recruitment of the protein arginine methyltransferase PRMT6, which mediates histone modification at H3R2me2a and represses transcription activity. We also found an enhanced binding of this mutant GATA1/PRMT6 complex to the transcriptional regulatory elements of GATA1's target genes. Moreover, treatment of the PRMT6 inhibitor MS023 could partially rescue the inhibited transcriptional and impaired erythroid differentiation caused by the GATA1 mutation. Taken together, our results provide molecular insights into erythropoiesis in which mutation leads to partial loss of GATA1 function and the broader role of PRMT6 and its inhibitor MS023 in congenital anemia, highlighting PRMT6 binding as a negative factor of GATA1 transcriptional activity in aberrant hematopoiesis.

Immune desert in MMR-deficient tumors predicts poor responsiveness of immune checkpoint inhibition.

Background: Although many efforts have been devoted to identify biomarkers to predict the responsiveness of immune checkpoint inhibitors, including expression of programmed death-ligand 1 (PD-L1) and major histocompatibility complex (MHC) I, microsatellite instability (MSI), mismatch repair (MMR) defect, tumor mutation burden (TMB), tertiary lymphoid structures (TLSs), and several transcriptional signatures, the sensitivity of these indicators remains to be further improved. Materials and methods: Here, we integrated T-cell spatial distribution and intratumor transcriptional signals in predicting the response to immune checkpoint therapy in MMR-deficient tumors including tumors of Lynch syndrome (LS). Results: In both cohorts, MMR-deficient tumors displayed personalized tumor immune signatures, including inflamed, immune excluded, and immune desert, which were not only individual-specific but also organ-specific. Furthermore, the immune desert tumor exhibited a more malignant phenotype characterized by low differentiation adenocarcinoma, larger tumor sizes, and higher metastasis rate. Moreover, the tumor immune signatures associated with distinct populations of infiltrating immune cells were comparable to TLSs and more sensitive than transcriptional signature gene expression profiles (GEPs) in immunotherapy prediction. Surprisingly, the tumor immune signatures might arise from the somatic mutations. Notably, patients with MMR deficiency had benefited from the typing of immune signatures and later immune checkpoint inhibition. Conclusion: Our findings suggest that compared to PD-L1 expression, MMR, TMB, and GEPs, characterization of the tumor immune signatures in MMR-deficient tumors improves the efficiency of predicting the responsiveness of immune checkpoint inhibition.

Advances in immunology and immunotherapy for mesenchymal gastrointestinal cancers.

Mesenchymal gastrointestinal cancers are represented by the gastrointestinal stromal tumors (GISTs) which occur throughout the whole gastrointestinal tract, and affect human health and economy globally. Curative surgical resections and tyrosine kinase inhibitors (TKIs) are the main managements for localized GISTs and recurrent/metastatic GISTs, respectively. Despite multi-lines of TKIs treatments prolonged the survival time of recurrent/metastatic GISTs by delaying the relapse and metastasis of the tumor, drug resistance developed quickly and inevitably, and became the huge obstacle for stopping disease progression. Immunotherapy, which is typically represented by immune checkpoint inhibitors (ICIs), has achieved great success in several solid tumors by reactivating the host immune system, and been proposed as an alternative choice for GIST treatment. Substantial efforts have been devoted to the research of immunology and immunotherapy for GIST, and great achievements have been made. Generally, the intratumoral immune cell level and the immune-related gene expressions are influenced by metastasis status, anatomical locations, driver gene mutations of the tumor, and modulated by imatinib therapy. Systemic inflammatory biomarkers are regarded as prognostic indicators of GIST and closely associated with its clinicopathological features. The efficacy of immunotherapy strategies for GIST has been widely explored in pre-clinical cell and mouse models and clinical experiments in human, and some patients did benefit from ICIs. This review comprehensively summarizes the up-to-date advancements of immunology, immunotherapy and research models for GIST, and provides new insights and perspectives for future studies.

LILRB1+ immune cell infiltration identifies immunosuppressive microenvironment and dismal outcomes of patients with ovarian cancer.

OBJECTIVE: Immune checkpoint inhibitors are commonly used in various types of cancer, but their efficacy in ovarian cancer (OC) is limited. Thus, identifying novel immune-related therapeutic targets is crucial. Leukocyte immunoglobulin-like receptor subfamily B1 (LILRB1), a key receptor of human leukocyte antigen G (HLA-G), is involved in immune tolerance, but its role in tumor immunity remains unclear. METHODS: In this study, immunofluorescence was used to identify the location of LILRB1 in OC. The effect of LILRB1 expression on clinical outcomes in 217 patients with OC was analyzed retrospectively. A total of 585 patients with OC from the TCGA database were included to explore the relationship between LILRB1 and tumor microenvironment characteristics. RESULTS: LILRB1 was found to be expressed in tumor cells (TCs) and immune cells (ICs). High LILRB1+ ICs, but not LILRB1+ TCs, were associated with advanced FIGO stage, shorter survival outcomes, and worse adjuvant chemotherapy responses in OC patients. LILRB1 expression was also associated with high M2 macrophage infiltration, reduced activation of dendritic cells, and dysfunction of CD8+ T cells, suggesting an immunosuppressive phenotype. The combination of LILRB1+ ICs and CD8+ T cell levels could be used to distinguish patients with different clinical survival results. Moreover, LILRB1+ ICs infiltration with CD8+ T cells absence indicated inferior responsiveness to anti-PD-1/PD-L1 therapy. CONCLUSIONS: Tumor-infiltrating LILRB1+ ICs could be applied as an independent clinical prognosticator and a predictive biomarker for therapy responsiveness to OC. Further studies targeting the LILRB1 pathway should be conducted in the future.

Systematic characterization of chromodomain proteins reveals an H3K9me1/2 reader regulating aging in C. elegans.

The chromatin organization modifier domain (chromodomain) is an evolutionally conserved motif across eukaryotic species. The chromodomain mainly functions as a histone methyl-lysine reader to modulate gene expression, chromatin spatial conformation and genome stability. Mutations or aberrant expression of chromodomain proteins can result in cancer and other human diseases. Here, we systematically tag chromodomain proteins with green fluorescent protein (GFP) using CRISPR/Cas9 technology in C. elegans. By combining ChIP-seq analysis and imaging, we delineate a comprehensive expression and functional map of chromodomain proteins. We then conduct a candidate-based RNAi screening and identify factors that regulate the expression and subcellular localization of the chromodomain proteins. Specifically, we reveal an H3K9me1/2 reader, CEC-5, both by in vitro biochemistry and in vivo ChIP assays. MET-2, an H3K9me1/2 writer, is required for CEC-5 association with heterochromatin. Both MET-2 and CEC-5 are required for the normal lifespan of C. elegans. Furthermore, a forward genetic screening identifies a conserved Arginine124 of CEC-5's chromodomain, which is essential for CEC-5's association with chromatin and life span regulation. Thus, our work will serve as a reference to explore chromodomain functions and regulation in C. elegans and allow potential applications in aging-related human diseases.

BMAL1 collaborates with CLOCK to directly promote DNA double-strand break repair and tumor chemoresistance.

Accumulating evidence indicates a correlation between circadian dysfunction and genomic instability. However, whether the circadian machinery directly regulates DNA damage repair, especially in double-strand breaks (DSBs), remains poorly understood. Here, we report that in response to DSBs, BMAL1 is activated by ATM-mediated phosphorylation at S183. Phosphorylated BMAL1 is then localized to DNA damage sites, where it facilitates acetylase CLOCK to load in the chromatin, regulating the acetylation of histone H4 (H4Ac) at DSB sites. In this way, the BMAL1-CLOCK-H4Ac axis promotes the DNA end-resection to generate single-stranded DNA (ssDNA) and the subsequent homologous recombination (HR). BMAL1 deficient cells display defective HR, accumulation of unrepaired DSBs and genome instability. Accordingly, depletion of BMAL1 significantly enhances the sensitivity of adrenocortical carcinoma (ACC) to DNA damage-based therapy in vitro and in vivo. These findings uncover non-canonical function of BMAL1 and CLOCK in HR-mediated DSB repair, which may have an implication in cancer therapeutics.

Tyrosine kinase SRC-induced YAP1-KLF5 module regulates cancer stemness and metastasis in triple-negative breast cancer.

SRC is the first identified oncogene, and its aberrant activation has been implicated as a driving event in tumor initiation and progression. However, its role in cancer stemness regulation and the underlying regulatory mechanism are still elusive. Here, we identified a YAP1 tyrosine phosphorylation-dependent YAP1-KLF5 oncogenic module, as the key downstream mediator of SRC kinase regulating cancer stemness and metastasis in triple-negative breast cancer (TNBC). SRC was overexpressed in TNBC patient tissues and its expression level was highly correlated with the tumor malignancy. SRC activation induced, while inhibition of SRC kinase reduced the cancer stemness, tumor cell growth and metastasis in vitro and in vivo. Transcriptomic and proteomic analysis revealed that SRC-mediated YAP1 tyrosine phosphorylation induced its interaction with Kruppel-like factor 5 (KLF5) to form a YAP1/TEAD-KLF5 complex in TNBC cells. YAP1-KLF5 association further promoted TEAD-mediated transcriptional program independently of canonical Hippo kinases, which eventually gave rise to the enhanced cancer stemness and metastasis. Disruption of YAP1-KLF5 module in TNBC cells dramatically attenuated the SRC-induced cancer stemness and metastasis in vitro and in vivo. Accordingly, co-upregulations of SRC and YAP1-KLF5 module in TNBC tissues were significantly positively correlated with the tumor malignance. Altogether, our work presents a novel tyrosine phosphorylation-dependent YAP1-KLF5 oncogenic module governing SRC-induced cancer stemness and metastasis in TNBC. Therefore, targeting YAP1/KLF5-mediated transcription may provide a promising strategy for TNBC treatment with SRC aberrantly activation.

Targeting NAD metabolism regulates extracellular adenosine levels to improve the cytotoxicity of CD8+ effector T cells in the tumor microenvironment of gastric cancer.

PURPOSE: Nicotinamide adenine dinucleotide (NAD+) is closely related to the pathogenesis of tumors. However, the effect of NAD+ metabolism of gastric cancer (GC) cells on immune cells remains unexplained. We targeted nicotinamide phosphoribosyltransferase (NAMPT), a rate-limiting enzyme in the NAD+ synthesis salvage pathway, to observe its effect in the immune microenvironment. METHODS: NAMPT of GC cell lines was inhibited by using the small molecule inhibitor (FK866) and short hairpin RNA (shRNA). CCK-8 test and flow cytometry were performed to detect cell viability and apoptosis. Immunofluorescence was used to observe changes in mitochondrial membrane potential (MMP).The transfected GC cells (AGS) and patient-derived organoids (PDOs) were cocultured with activated PBMCs, followed by flow cytometric analysis (FCA) for cytokines and inhibitory marker. The level of NAD and ATP of GC cells (AGS & MKN45) was tested combined with NMN and CD39 inhibitor. RESULTS: Targeting NAD+ by FK866 obviously reduced MMP, which ultimately inhibited proliferation and increased the apoptosis of GC cells. NAMPT silencing reduced intracellular NAD and ATP，further decreased extracellular adenosine. Meawhile, the cytokines of CD8+T cells were significantly increased after cocultured with transfected AGS, and the expression of PD-1 was distinctly decreased. NMN reversed the effect of shNAMPT and enhanced the immunosuppression. Consistent results were obtained by coculturing PBMCs with PDOs. CONCLUSION: Restraining the function of NAMPT resulted in the functional improvement of effector CD8+ T cells by decreasing extracellular adenosine levels and inducing apoptosis of GC cells simultaneously. Therefore, this study demonstrates that NAMPT can be an effective target for gastric cancer immunotherapy.

SRC kinase-mediated signaling pathways and targeted therapies in breast cancer.

Breast cancer (BC) has been ranked the most common malignant tumor throughout the world and is also a leading cause of cancer-related deaths among women. SRC family kinases (SFKs) belong to the non-receptor tyrosine kinase (nRTK) family, which has eleven members sharing similar structure and function. Among them, SRC is the first identified proto-oncogene in mammalian cells. Oncogenic overexpression or activation of SRC has been revealed to play essential roles in multiple events of BC progression, including tumor initiation, growth, metastasis, drug resistance and stemness regulations. In this review, we will first give an overview of SRC kinase and SRC-relevant functions in various subtypes of BC and then systematically summarize SRC-mediated signaling transductions, with particular emphasis on SRC-mediated substrate phosphorylation in BC. Furthermore, we will discuss the progress of SRC-based targeted therapies in BC and the potential future direction.

Calcaneous interlocking nail treatment for calcaneous fracture: a multiple center retrospective study.

BACKGROUND: Minimally invasive treatments for calcaneous fractures have the same outcomes and fewer complications. However, they are technically demanding, and there are a lack reduction tools. To overcome these problems, a calcaneous interlocking nail system was developed that can make reduction and fixation minimally invasive and effective. We retrospectively studied the calcaneous fracture variables intraoperatively and followed up to evaluate the outcomes of patients treated with the calcaneous interlocking nail system. METHODS: All patients in 7 institutions between October 2020 and May 2021 who had calcaneous fractures treated with calcaneous interlocking nails were retrospectively analyzed. The patient characteristics, including age, sex, injury mechanism, Sanders type classification, smoking status, and diabetes were recorded. The calcaneous interlocking nail and standard surgical technique were introduced. The intraoperative variables, including days waiting for surgery, surgery time, blood loss, incision length, and fluoroscopy time, were recorded. The outcomes of complications, AOFAS scores and VAS scores were recorded and compared with other similar studies. RESULTS: Fifty-nine patients were involved in this study; 54 were male; 5 were female; and they had an average age of 47.5 ± 9.2 years (range 25-70). 2 of these fractures were Sanders type I, 28 of these fractures were Sanders type II, 27 of these fractures were Sanders type III, and 2 of these were Sanders type IV. The surgery time was 131.9 ± 50.5 (30-240) minutes on average. The blood loss was 36.9 ± 41.1 (1-250) ml. The average incision length was 3.5 ± 1.8 (1-8) cm; 57 were sinus tarsi incisions; and 2 were closed fixations without incisions. The average fluoroscopy time was 12.3 ± 3.6 (10-25) seconds during the surgery. The VAS score of patients on the day after surgery was 2.4 ± 0.7 (1-3). The AOFAS ankle-hindfoot score in patients who had a follow-up of at 12 months was 93.3 ± 3.6(85-99). During the follow-up, all patients' functional outcomes were good. One patient had a superficial infection. The rate of complications of the 59 patients was 1.7% (1/59). CONCLUSION: The calcaneous interlocking nail system can have satisfactory reduction and fixation in calcaneous fractures, even in Sanders type IV. The outcomes of follow-up showed good function. The calcaneous interlocking nail could be an alternative method for minimally invasive calcaneous fracture fixation.

[Construction of Nalm6-Cas9 Cell Line for Genome-Wide Translocation Sequencing].

OBJECTIVE: In order to conduct high-throughput genome-wide translocation sequencing based on CRISPR/Cas9, Nalm6-cas9 monoclonal cell line expressing Cas9 protein was constructed by lentivirus transduction. METHODS: Lentiviral vectors LentiCas9-Blast, pSPAX2, and pMD2.G were used to co-transfect HEK293T cells to obtain recombinant lentivirus. After Nalm6 cells were infected with the recombinant lentivirus, the cells were screened by Blasticidin, and multiple monoclonal cell lines expressing Cas9 protein were obtained by limited dilution. Western blot was used to detect the expression level of Cas9 protein in monoclonal cell lines, and cell count analysis was used to detect the proliferation activity of monoclonal cell lines. LentiCRISPRV2GFP-Δcas9, LentiCRISPRV2GFP-Δcas9-AF4, LentiCRISPRV2GFP-Δ cas9-MLL plasmids were constructed, and transfected with pSPAX2 and pMD2.G, respectively. T vector cloning was used to detect the function of Cas9 protein in Nalm6-Cas9 monoclonal cell line infected with virus. RESULTS: Western blot showed that Nalm6-Cas9_1-6 monoclonal cell line had high expression of Cas9 protein. Cell count analysis showed that high expression of Cas9 protein in Nalm6-Cas9_1-6 monoclonal cell line did not affect cell proliferation activity. The Nalm6-Cas9_1-6 monoclonal cell line had high cleavage activity, and the editing efficiency of AF4 and MLL genes was more than 90% which was determined by T vector cloning. CONCLUSION: Nalm6-Cas9_1-6 monoclonal cell line stably expressing highly active Cas9 protein was obtained, which provided a basis for exploring the translocation of MLL in therapy-related leukemias based on CRISPR/Cas9 genome-wide high-throughput genome-wide translocation sequencing.

Identification of mutant p53-specific proteins interaction network using TurboID-based proximity labeling.

BACKGROUNDS: Although several studies on mutant p53 reported cancer-promoting activities via "gain-of-function", the mechanism underlying these differences in function between p53 R175H, R175P, and p53 wild-type (WT) remains unclear. METHODS: Linking miniTurbo with p53 WT, R175H, and R175P, the expression of fusion and biotinylated proteins were assessed by Western blotting. The function and subcellular localization of fusion proteins were detected by apoptosis assay and immunofluorescence, respectively. Biotinylated proteins were analyzed by liquid chromatography-tandem mass spectrometry, followed by bioinformatics analysis. Small-scale pull-downs and Co-Immunoprecipitation were performed to validate the interaction between mutant or p53 WT and biotinylated proteins. RESULTS: The fusion protein's cellular localization and function were consistent with those of previous studies on the corresponding p53. Comparative profiles of R175H versus WT showed that most of the interacting proteins belonged to the intracellular organelle lumen, and the pathways involved were metabolism and genetic information processing. Comparative profiles of R175P versus WT suggested that the majority of the interacting proteins belonged to the intracellular organelle lumen and the extracellular membrane-bounded organelle, and the pathways involved were metabolism and genetic information processing pathways. The comparison between R175H and R175P revealed that most interacting proteins belonged to the organelle lumen, and pathways involved were genetic information processing pathways. Finally, the mutation of p53 significantly altered the interaction with the target proteins were confirmed. CONCLUSION: We verified the reliability of the miniTurbo system and obtained candidate targets of mutant p53, which provided new thoughts on the mechanism of mutant p53 gain-of-function and new potential targets for cancer therapy.

Comprehensive Analysis of the Expression and Prognostic Value of LMAN2 in HER2+ Breast Cancer.

Lectin, Mannose Binding 2 (LMAN2) encodes a type I transmembrane lectin that shuttles between the plasma membrane, the Golgi apparatus, and the endoplasmic reticulum. However, its expression, prognosis, and function in invasive breast carcinoma remain unknown. Nine databases were consulted to evaluate LMAN2 expression and prognosis in breast cancer. The possible function of LMAN2 in breast cancer was investigated in the Human Cell Landscape (HCL) database, Gene Regulatory Network database (GRNdb), and CancerSEA database. Moreover, N6-methyladenosine (m6A) modifications were analyzed using the RMBase v2.0 and M6A2Target databases. Seven databases were then used to analyze the potential action mechanisms of LMAN2. Our findings suggest that LMAN2, which is expressed at a high level in breast cancer, is linked to an unfavorable prognosis. Therefore, LMAN2 has the potential to be utilized as a treatment target in breast cancer. Furthermore, the single-cell analysis illustrated that LMAN2 expression had a positive link to breast cancer stemness, proliferation, metastasis, and differentiation. Moreover, m6A modifications were found in the LMAN2 gene. Consequently, modifications to m6A methylation may influence LMAN2 expression, which is associated with the homologous recombination (HR) in its DNA damage repair pathway .

Aberrantly expressed Wnt5a in nurse-like cells drives resistance to Venetoclax in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of neoplastic B lymphocytes with high levels of Wnt5a in the plasma. Currently, the cell source of Wnt5a remains controversial. The receptor of Wnt5a is ROR1, whose expression is associated with disease progression and resistance to venetoclax, a BCL-2 inhibitor approved for the treatment of CLL. In this study, we found that the levels of Wnt5a in the plasma of CLL patients were positively correlated with absolute monocyte counts, but not lymphocyte counts. We cultured monocyte-derived nurse-like cells (NLCs) from patients with CLL, and detected Wnt5a expressed in NLCs. Flow cytometry and transwell assays showed that the antibody neutralizing Wnt5a inhibited the enhanced survival and migration in CLL cells co-cultured with NLCs. Furthermore, we performed a drug screening with CLL cells cultured with or without NLCs with a library containing 133 FDA-approved oncology drugs by using high-throughput flow cytometry. We observed a significant resistance to venetoclax in CLL cells co-cultured with NLCs. Immunoblot revealed the activation of NF-κB with enhanced expression of MCL-1 and BCL-XL in CLL cells co-cultured with NLCs. Neutralizing Wnt5a or blocking NF-κB pathway significantly decreased the expression of MCL-1 and BCL-XL, which leads to enhanced sensitivity to venetoclax in CLL cells co-cultured with NLCs. In conclusion, our data showed that NLCs could be one of the sources of Wnt5a detected in patients with CLL, and Wnt5a-induced NF-κB activation in the CLL microenvironment results in resistance to venetoclax in CLL cells.

Carrier-free multifunctional nanomedicine for intraperitoneal disseminated ovarian cancer therapy.

BACKGROUND: Ovarian cancer is the most lethal gynecological cancer which is characterized by extensive peritoneal implantation metastasis and malignant ascites. Despite advances in diagnosis and treatment in recent years, the five-year survival rate is only 25-30%. Therefore, developing multifunctional nanomedicine with abilities of promoting apoptosis and inhibiting migration on tumor cells would be a promising strategy to improve the antitumor effect. METHODS AND RESULTS: In this study, we developed a novel ACaT nanomedicine composed of alendronate, calcium ions and cyclin-dependent kinase 7 (CDK7) inhibitor THZ1. With the average size of 164 nm and zeta potential of 12.4 mV, the spherical ACaT nanoparticles were selectively internalized by tumor cells and effectively accumulated in the tumor site. Results of RNA-sequencing and in vitro experiments showed that ACaT promoted tumor cell apoptosis and inhibited tumor cell migration by arresting the cell cycle, increasing ROS and affecting calcium homeostasis. Weekly intraperitoneally administered of ACaT for 8 cycles significantly inhibited the growth of tumor and prolonged the survival of intraperitoneal xenograft mice. CONCLUSION: In summary, this study presents a new self-assembly nanomedicine with favorable tumor targeting, antitumor activity and good biocompatibility, providing a novel therapeutic strategy for advanced ovarian cancer.

Targeting MEX3A attenuates metastasis of breast cancer via ß-catenin signaling pathway inhibition.

Metastasis is the major cause of mortality in patients with breast cancer. Understanding the metastatic mechanism to guide clinical diagnoses and the treatment of breast cancer remains a challenge. We found that the expression of Mex-3 RNA binding family member A (MEX3A) was upregulated significantly and related to tumor grade in breast cancer. The results of in vitro and in vivo studies showed that knockdown of MEX3A inhibited the metastasis and impaired the stemness of breast cancer cells. Furthermore, activation of the ß-catenin signaling pathway was discovered as a molecular intermediate of MEX3A-mediated regulation. We also found that ectopic expression of ß-catenin restored the migration ability, invasion ability, and CD44+/CD24- percentage of MDA-MB-231 and BT549 cells when MEX3A was depleted. In addition, we revealed that MEX3A positively regulated the expression of ß-catenin by downregulating Dickkopf WNT signaling pathway inhibitor 1 (DKK1) expression. Therefore, a previously undiscovered role of MEX3A comprising a critical contribution to promoting metastasis and maintaining the stemness of breast cancer via the Wnt/ß-catenin pathway was demonstrated in the present study.

A chromodomain protein mediates heterochromatin-directed piRNA expression.

PIWI-interacting RNAs (piRNAs) play significant roles in suppressing transposons, maintaining genome integrity, and defending against viral infections. How piRNA source loci are efficiently transcribed is poorly understood. Here, we show that in Caenorhabditis elegans, transcription of piRNA clusters depends on the chromatin microenvironment and a chromodomain-containing protein, UAD-2. piRNA clusters form distinct focus in germline nuclei. We conducted a forward genetic screening and identified UAD-2 that is required for piRNA focus formation. In the absence of histone 3 lysine 27 methylation or proper chromatin-remodeling status, UAD-2 is depleted from the piRNA focus. UAD-2 recruits the upstream sequence transcription complex (USTC), which binds the Ruby motif to piRNA promoters and promotes piRNA generation. Vice versa, the USTC complex is required for UAD-2 to associate with the piRNA focus. Thus, transcription of heterochromatic small RNA source loci relies on coordinated recruitment of both the readers of histone marks and the core transcriptional machinery to DNA.

Mechanical Insights into Thiol-Mediated Synergetic Biotransformation of Cadmium and Selenium in Nematodes.

Cadmium ion (Cd2+) is a common environmental pollutant with high biotoxicity. Interestingly, the Cd2+ biotoxicity can be alleviated by the coexisting selenite (SeO32-), which induces the formation of cadmium selenide-rich nanoparticles (CdSe NPs) under the function of thiol-capping peptides. However, the detailed biochemical mechanisms by which Cd and Se are synergistically transformed into CdSe NPs in living organisms remain unclear so far. Here, we shed light on the molecular basis of such biotransformation processes in Caenorhabditis elegans by focusing on the roles of several key thiol-capping peptides. By monitoring the compositional and structural changes of the Cd and Se species and the genetic-level responses of nematodes, we revealed the specific roles of glutathione (GSH) and phytochelatins (PCs) in mediating the CdSe NP formation. With the aid of in vitro bioassembly assay and density functional theory calculations, the detailed Cd-Se interaction pathways were further deciphered: the ingested Cd binds predominantly to GSH and PCs in sequence, then further interacts with selenocysteine to form tetrahedral-structured PC2-Cd2-Sec2 complex, and ultimately grows into CdSe NPs. This work provides molecular-level insights into the Cd-Se interaction in C. elegans and lays a basis for controlling the ecological and health risks of heavy metals in polluted environment.

RANK promotes colorectal cancer migration and invasion by activating the Ca2+-calcineurin/NFATC1-ACP5 axis.

The tumor necrosis factor (TNF) receptor superfamily member 11a (TNFRSF11a, also known as RANK) was demonstrated to play an important role in tumor metastasis. However, the specific function of RANK in colorectal cancer (CRC) metastasis and the underlying mechanism are unknown. In this study, we found that RANK expression was markedly upregulated in CRC tissues compared with that in matched noncancerous tissues. Increased RANK expression correlated positively with metastasis, higher TNM stage, and worse prognosis in patients with CRC. Overexpression of RANK promoted CRC cell metastasis in vitro and in vivo, while knockdown of RANK decreased cell migration and invasion. Mechanistically, RANK overexpression significantly upregulated the expression of tartrate-resistant acid phosphatase 5 (TRAP/ACP5) in CRC cells. Silencing of ACP5 in RANK-overexpressing CRC cells attenuated RANK-induced migration and invasion, whereas overexpression of ACP5 increased the migration and invasion of RANK-silencing cells. The ACP5 expression was transcriptionally regulated by calcineurin/nuclear factor of activated T cells c1 (NFATC1) axis. The inhibition of calcineurin/NFATC1 significantly decreased ACP5 expression, and attenuated RANK-induced cell migration and invasion. Furthermore, RANK induced phospholipase C-gamma (PLCγ)-mediated inositol-1,4,5-trisphosphate receptor (IP3R) axis and stromal interaction molecule 1 (STIM1) to evoke calcium (Ca2+) oscillation. The RANK-mediated intracellular Ca2+ mobilization stimulated calcineurin to dephosphorylate NFATC1 and induce NFATC1 nuclear translocation. Both blockage of PLCγ-IP3R axis and STIM1 rescued RANK-induced NFATC1 nuclear translocation, ACP5 expression, and cell metastasis. Our study revealed the functional expression of RANK in human CRC cells and demonstrated that RANK induced the Ca2+-calcineurin/NFATC1-ACP5 axis in the regulation of CRC metastasis, that might be amenable to therapeutic targeting.