Knockdown of Legumain Suppresses Cervical Cancer Cell Migration and Invasion

Investigation of prognostic values of immune infiltration and LGMN expression in the microenvironment of osteosarcoma

BACKGROUND

Osteosarcoma (OS), the most common primary malignant bone tumor, predominantly affects children and young adults and is characterized by high invasiveness and poor prognosis. Despite therapeutic advancements, the survival rate remains suboptimal, indicating an urgent need for novel biomarkers and therapeutic targets. This study aimed to investigate the prognostic significance of LGMN expression and immune cell infiltration in the tumor microenvironment of OS.

METHODS

We performed an integrative bioinformatics analysis utilizing the GEO and TARGET-OS databases to identify differentially expressed genes (DEGs) associated with LGMN in OS. We conducted Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) to explore the biological pathways and functions. Additionally, we constructed protein-protein interaction (PPI) networks, a competing endogenous RNA (ceRNA) network, and applied the CIBERSORT algorithm to quantify immune cell infiltration. The diagnostic and prognostic values of LGMN were evaluated using the area under the receiver operating characteristic (ROC) curve and Cox regression analysis. Furthermore, we employed Consensus Clustering Analysis to explore the heterogeneity within OS samples based on LGMN expression.

RESULTS

The analysis revealed significant upregulation of LGMN in OS tissues. DEGs were enriched in immune response and antigen processing pathways, suggesting LGMN's role in immune modulation within the TME. The PPI and ceRNA network analyses provided insights into the regulatory mechanisms involving LGMN. Immune cell infiltration analysis indicated a correlation between high LGMN expression and increased abundance of M2 macrophages, implicating an immunosuppressive role. The diagnostic AUC for LGMN was 0.799, demonstrating its potential as a diagnostic biomarker. High LGMN expression correlated with reduced overall survival (OS) and progression-free survival (PFS). Importantly, Consensus Clustering Analysis identified two distinct subtypes of OS, highlighting the heterogeneity and potential for personalized medicine approaches.

CONCLUSIONS

Our study underscores the prognostic value of LGMN in osteosarcoma and its potential as a therapeutic target. The identification of LGMN-associated immune cell subsets and the discovery of distinct OS subtypes through Consensus Clustering Analysis provide new avenues for understanding the immunosuppressive TME of OS and may aid in the development of personalized treatment strategies. Further validation in larger cohorts is warranted to confirm these findings.

Pigmented Microbial Extract (PMB) from Exiguobacterium Species MB2 Strain (PMB1) and Bacillus subtilis Strain MB1 (PMB2) Inhibited Breast Cancer Cells Growth In Vivo and In Vitro

Breast cancer (BC) continues to be one of the major causes of cancer deaths in women. Progress has been made in targeting hormone and growth factor receptor-positive BCs with clinical efficacy and success. However, little progress has been made to develop a clinically viable treatment for the triple-negative BC cases (TNBCs). The current study aims to identify potent agents that can target TNBCs. Extracts from microbial sources have been reported to contain pharmacological agents that can selectively inhibit cancer cell growth. We have screened and identified pigmented microbial extracts (PMBs) that can inhibit BC cell proliferation by targeting legumain (LGMN). LGMN is an oncogenic protein expressed not only in malignant cells but also in tumor microenvironment cells, including tumor-associated macrophages. An LGMN inhibition assay was performed, and microbial extracts were evaluated for in vitro anticancer activity in BC cell lines, angiogenesis assay with chick chorioallantoic membrane (CAM), and tumor xenograft models in Swiss albino mice. We have identified that PMB from the Exiguobacterium (PMB1), inhibits BC growth more potently than PMB2, from the Bacillus subtilis strain. The analysis of PMB1 by GC-MS showed the presence of a variety of fatty acids and fatty-acid derivatives, small molecule phenolics, and aldehydes. PMB1 inhibited the activity of oncogenic legumain in BC cells and induced cell cycle arrest and apoptosis. PMB1 reduced the angiogenesis and inhibited BC cell migration. In mice, intraperitoneal administration of PMB1 retarded the growth of xenografted Ehrlich ascites mammary tumors and mitigated the proliferation of tumor cells in the peritoneal cavity in vivo. In summary, our findings demonstrate the high antitumor potential of PMB1.

Clonorchis sinensis legumain promotes migration and invasion of cholangiocarcinoma cells via regulating tumor-related molecules

BACKGROUND

Clonorchis sinensis infection causes serious pathological changes in the bile duct and is highly correlated with cholangiocarcinoma. The excretory-secretory products (ESP) of C. sinensis play a critical role in the oncogenesis and progression of cholangiocarcinoma, while the components and precise mechanism remain unclear. Here, we evaluated the function of C. sinensis legumain (Cslegumain) in promoting the invasion and migration of cholangiocarcinoma cells and the mechanism involved.

METHODS

The structural and molecular characteristics of Cslegumain were predicted and analyzed using the online program Phyre2. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical staining were performed to test the transcriptional level of Cslegumain and its localization in the adult. Native Cslegumain was detected by western blotting assay. The effects of Cslegumain on the proliferation, invasion and migration of cholangiocarcinoma cells were checked using CCK-8 assay, Matrigel transwell assay and scratch wound healing assay. Expression levels of tumor-related molecules regulated by Cslegumain were evaluated by qRT-PCR and western blotting assay.

RESULTS

Cslegumain showed high similarity with human legumain in the secondary and tertiary structures and displayed higher transcriptional levels in the adult worm than in the metacercariae. Native Cslegumain was detected in a catalytic form and was localized mainly in the intestine of the C. sinensis adult and epithelial cells of the intrahepatic bile duct. After transfection into RBE cells, Cslegumain showed high ability in promoting the invasion and migration but not the proliferation of cholangiocarcinoma RBE cells. Furthermore, the expression levels of some molecules including E-cadherin and N-cadherin were downregulated, while the levels of α-actinin 4, β-catenin and inducible nitric oxide synthase (iNOS) were upregulated.

CONCLUSIONS

Our findings indicated that Cslegumain showed very similar structures as those of human legumain and could promote the invasion and migration of cholangiocarcinoma cells by regulating some tumor-related molecules.

Role of LGMN in tumor development and its progression and connection with the tumor microenvironment

Legumain (LGMN) has been demonstrated to be overexpressed not just in breast, prostatic, and liver tumor cells, but also in the macrophages that compose the tumor microenvironment. This supports the idea that LGMN is a pivotal protein in regulating tumor development, invasion, and dissemination. Targeting LGMN with siRNA or chemotherapeutic medicines and peptides can suppress cancer cell proliferation in culture and reduce tumor growth in vivo. Furthermore, legumain can be used as a marker for cancer detection and targeting due to its expression being significantly lower in normal cells compared to tumors or tumor-associated macrophages (TAMs). Tumor formation is influenced by aberrant expression of proteins and alterations in cellular architecture, but the tumor microenvironment is a crucial deciding factor. Legumain (LGMN) is an in vivo-active cysteine protease that catalyzes the degradation of numerous proteins. Its precise biological mechanism encompasses a number of routes, including effects on tumor-associated macrophage and neovascular endothelium in the tumor microenvironment. The purpose of this work is to establish a rationale for thoroughly investigating the function of LGMN in the tumor microenvironment and discovering novel tumor early diagnosis markers and therapeutic targets by reviewing the function of LGMN in tumor genesis and progression and its relationship with tumor milieu.

Autocrine pro-legumain promotes breast cancer metastasis via binding to integrin αvβ3

Tumor metastasis is the leading cause of cancer-associated mortality. Unfortunately, the underlying mechanism of metastasis is poorly understood. Expression of legumain (LGMN), an endo-lysosomal cysteine protease, positively correlates with breast cancer metastatic progression and poor prognosis. Here, we report that LGMN is secreted in the zymogen form by motile breast cancer cells. Through binding to cell surface integrin αvβ3 via an RGD motif, the autocrine pro-LGMN activates FAK-Src-RhoA signaling in cancer cells and promotes cancer cell migration and invasion independent of LGMN protease activity. Either silencing LGMN expression or mutationally abolishing pro-LGMN‒αvβ3 interaction significantly inhibits cancer cell migration and invasion in vitro and breast cancer metastasis in vivo. Finally, we developed a monoclonal antibody against LGMN RGD motif, which blocks pro-LGMN‒αvβ3 binding, and effectively suppresses cancer cell migration and invasion in vitro and breast cancer metastasis in vivo. Thus, disruption of pro-LGMN‒integrin αvβ3 interaction may be a potentially promising strategy for treating breast cancer metastasis.

Active legumain promotes invasion and migration of neuroblastoma by regulating epithelial-mesenchymal transition

Neuroblastoma (NB) is a commonly occurring malignancy in children. Epithelial-mesenchymal transition (EMT) is an adaptive change in promoting tumor metastasis. As an important factor in regulating tumor metastasis, whether legumain could promote metastasis of NB by EMT is still unexplored. Legumain is the active form of prolegumain, abundant in tumor plasma. So in the current study, different forms of legumain were identified in NB. Second, correlation analysis of N-cadherin and active legumain was identified by western blot analysis. Third, legumain gene amplification or gene knockdown were proceeded to examine the effect of legumain on EMT by scratch and transwell assay; meanwhile, active mature legumain or its asparagine endopeptidase (AEP) inhibitor was also added in. Finally, legumain can be detected differently in NB cells. Changes in legumain could influence NB metastasis by regulating EMT markers (e.g., N-cadherin, vimentin, and slug). Besides, the effect of legumain on EMT by its AEP activity was proved by intervention experiment of AEP gene transfection and gene knockdown experiments or adding recombinant human legumain suspension or specific inhibitor of AEP in NB cells (p < 0.05). These results suggest that legumain can promote invasion and migration of NB by regulating EMT, and EMT of NB is regulated by AEP activity of legumain, which can be inhibited by a specific AEP inhibitor.

A Novel Legumain-Like Protease in Macrobrachium nipponense: Identification, Characterization, and Function Analysis in Ovary Maturation

Legumain, also called aspartic endopeptidase (AEP), is a member of the cysteine protease family and is involved in various physiological processes. In this study, we analyzed the characteristics of a novel legumain-like (named Mn-Lel) in the female oriental river prawn, Macrobrachium nipponense, which is involved in ovary maturation. The Mn-Lel is 1,454 bp in length, including a 1,290-bp open reading frame that encodes 430 amino acids. qPCR analysis indicated that Mn-Lel is specifically highly expressed in the hepatopancreas and ovaries of female prawns. It is rarely expressed in embryogenesis, weakly expressed in early larval development stages, and then significantly increased after metamorphosis, which indicated that Mn-Lel is not a maternal gene and mainly plays a role in adults. During the different ovarian stages, Mn-Lel expression in the hepatopancreas had no obvious rules, while its expression in the ovaries had a significant peak in stage III. In situ hybridization studies revealed that Mn-Lel is localized in the oocyte of the ovary. Changes in the gonadosomatic index confirmed the inhibitory effects of Mn-Lel dsRNA on ovary maturation. These results suggest that Mn-Lel has a key role in promoting ovary maturation.

Silencing of hsa_circ_0009035 Suppresses Cervical Cancer Progression and Enhances Radiosensitivity through MicroRNA 889-3p-Dependent Regulation of HOXB7

Circular RNAs (circRNAs), a novel type of endogenous noncoding RNAs, have been identified as critical regulators in human carcinogenesis. Here, we investigated the precise actions of hsa_circ_0009035 in the progression and radioresistance of cervical cancer (CC). The levels of hsa_circ_0009035, microRNA 889-3p (miR-889-3p), and homeobox B7 (HOXB7) were detected by quantitative real-time PCR (qRT-PCR) or Western blotting. RNase R and actinomycin D assays were used to assess the stability of hsa_circ_0009035. Cell proliferation, cell cycle progression, apoptosis, migration, and invasion were gauged with Cell Counting Kit-8 (CCK-8), flow cytometry, and transwell assays. Cell colony formation and survival were determined by the colony formation assay. Targeted correlations among hsa_circ_0009035, miR-889-3p, and HOXB7 were examined by the dual-luciferase reporter, RNA immunoprecipitation (RIP), or RNA pulldown assay. Animal studies were performed to evaluate the impact of hsa_circ_0009035 on tumor growth. We found that hsa_circ_0009035 was highly expressed in CC tissues and cells, and it was associated with the radioresistance of CC patients. Moreover, the silencing of hsa_circ_0009035 inhibited CC cell proliferation, migration, invasion, and it enhanced apoptosis and radiosensitivity in vitro and weakened tumor growth in vivo. Mechanistically, hsa_circ_0009035 directly targeted miR-889-3p by binding to miR-889-3p, and hsa_circ_0009035 modulated HOXB7 expression through miR-889-3p. HOXB7 was a functional target of miR-889-3p in regulating CC progression and radioresistance in vitro, and hsa_circ_0009035 modulated CC progression and radioresistance in vitro by miR-889-3p. Our current study first identified hsa_circ_0009035 as an important regulator of CC progression and radioresistance at least in part through targeting the miR-889-3p/HOXB7 axis, highlighting its significance as a potential therapeutic target for CC treatment.

The Mechanism of Asparagine Endopeptidase in the Progression of Malignant Tumors: A Review

Asparagine endopeptidase (AEP), also called legumain, is currently the only known cysteine protease that specifically cleaves peptide bonds in asparaginyl residue in the mammalian genome. Since 2003, AEP has been reported to be widely expressed in a variety of carcinomas and is considered a potential therapeutic target. In the following years, researchers intensively investigated the substrates of AEP and the mechanism of AEP in partial tumors. With the identification of substrate proteins such as P53, integrin αvβ3, MMP-2, and MMP-9, the biochemical mechanism of AEP in carcinomas is also more precise. This review will clarify the probable mechanisms of AEP in the progression of breast carcinoma, glioblastoma, gastric carcinoma, and epithelial ovarian carcinoma. This review will also discuss the feasibility of targeted therapy with AEP inhibitor (AEPI) in these carcinomas.

Down-regulation of lncRNA PCGEM1 inhibits cervical carcinoma by modulating the miR-642a-5p/LGMN axis

LncRNA PCGEM1 (PCGEM1) has been reported to exert essential effects on the development and progress of various tumors, while the detailed effects and possible mechanisms of PCGEM1 in cervical carcinoma remain unknown. In the present study, PCGEM1 was over-expressed in cervical carcinoma cells as evidenced by real-time quantitative polymerase chain reaction (RT-qPCR) assay. Knockdown of PCGEM1 significantly repressed proliferation, migration, and invasion, while induced G1 arrest in cervical carcinoma cells. In addition, PCGEM1 was predicted to target miR-642a-5p by bioinformatics software, which was further confirmed by luciferase reporter assay. Besides, RT-qPCR assay indicated that miR-642a-5p expression was decreased in cervical carcinoma cells and knockdown of PCGEM1 could accelerate miR-642a-5p expression. Moreover, inhibition of miR-642a-5p partly abolished the functions of PCGEM1 knockdown on proliferation, cell cycle, migration and invasion of cervical carcinoma cells. Furthermore, miR-642a-5p could bind to the 3'-UTR of LGMN, which was over-expressed in the cervical carcinoma cells. Suppression of LGMN partly restored the functions of miR-642a-5p inhibitor on proliferation, cell cycle distribution, migration and invasion in the cervical carcinoma cells treated with the PCGEM1 shRNA. Taken together, our data indicated that knockdown of PCGEM1 inhibited proliferation, migration and invasion in cervical carcinoma by modulating the miR-642a-5p/ LGMN axis.

Evaluation of the anti-cervical cancer effect of a prodrug ：CBZ-AAN-DOX with hypoxic cell culture and tumor-bearing zebrafish models

BACKGROUND

Prodrugs are medications or compounds that, after administration, can be converted into pharmacologically active drugs through metabolism. Unlike conventional drugs, prodrugs have reduced adverse or unintended effects, which could become critical limitations in treatments such as chemotherapy. Previously through computer-aided drug design and chemical synthesis, we have obtained and examined a prodrug N-benzyloxycarbonyl-Ala-Asn-Doxorubicin (CBZ-AAN-DOX). CBZ-AAN-DOX is essentially Doxorubicin that is chemically-modified with tripeptides to target Legumain, a highly expressed protein in cancer cells and is involved in tumor metastasis and tumor microvessel formation. The difficulty to test the safety and efficacy of the prodrug (including the pharmacodynamic parameters of CBZ-AAN-DOX on metastasis and invasion of tumors, as well as cardiac and vascular toxicity) primarily comes from the lack of appropriate experimental models.

METHODS

Human cervical cancer cell lines CaSki under hypoxic conditions were used to evaluate the cell viability by CCK-8 assay after the prodrug treatment. Western blotting method was performed for Legumain protein determination in the cell culture. Wound healing and transwell invasion assays were performed to determine the effects of the prodrug on tumor metastasis and invasion, respectively. Zebrafish models were constructed for toxicity and angiogenesis visual analysis after in vivo treatment with the prodrug.

RESULTS

The CCK-8 results showed that CBZ-AAN-DOX exhibits an IC50 of 28.7 μM in 48 h on CaSki cells that had a lower cell inhibition rate than DOX 80.3 μM for 24 h. Legumain expression was significantly increased in a time-dependent manner in 48 h under hypoxia conditions. The results also showed that 13.9 μM of the prodrug significantly inhibited the migration and invasion of cells and the effects were significantly stronger than that of 41.8 μM of DOX under hypoxia conditions after 48 h. The effects of 160 μM of the prodrug on the survival rate of zebrafish after 72 h and heart-toxicity showed no obvious abnormalities. Cell metastasis and angiogenesis were also inhibited in tumor-bearing zebrafish model.

CONCLUSION

The findings in this study demonstrated that CBZ-AAN-DOX is a promising chemotherapy candidate with low toxicity and high efficiency for cervical cancer. Remarkably, the hypoxic culture model together with the zebrafish model serve as a good system for the evaluation of the toxicity, targeting and impact of the prodrug on tumor invasion and metastasis.

Differences in serum proteins in traditional Chinese medicine constitutional population: Analysis and verification

Traditional Chinese medicine assigns individuals into different categories called "constitutions" to help guide the clinical treatment according to subjective physiologic, psychologic analyses, large-scale clinical observations, and epidemiologic studies. To further explore more objective expressions of constitutions, antibody microarrays were used to analyze the serologic protein profiles of two different constitutions, a balanced (or healthy) constitution (BC) and the dampness constitution (DC) comprising phlegm-dampness and damp-heat constitutions. The profiles of changing constitutions across time were also analyzed. Nineteen differentially expressed proteins between the two groups were identified, with known biologic functions involved in immunity and inflammation. This proteomic study may provide a biologic explanation why the BC is different than the dampness constitution.

Increased Legumain/Smad3 expression in atherosclerotic plaque of rat thoracic aorta

OBJECTIVES

The purpose of this study was to investigate the role of legumain in the formation and stability of atherosclerotic plaque, as well as to explore the association between legumain with Smad3 pathway in a rat atherosclerosis model.

METHODS

Rat with thoracic aorta atherosclerosis was established and received treatment with statin (n = 15 each) or controls (n = 10). Serum level of legumain was determined by enzyme-linked immunosorbent assay. Legumain and Smad3 aortic expression levels were assessed by immunohistochemistry and fluorescence microscopy. Protein and mRNA levels were analyzed using Western blot analysis and reverse transcriptase coupled polymerase chain reaction, respectively.

RESULTS

The atherosclerotic group showed higher serum legumain level than control and statin group. Expression of legumain and Smad3 in macrophages and foam cells was increased in atherosclerotic group compared to control and statin group. The protein and mRNA levels of legumain and Smad3 were significantly attenuated by statin treatment (p < 0.05). For all groups, legumain expression was correlated linearly with Smad3 at mRNA (coefficient: 0.94) and protein (coefficient: 097) level.

CONCLUSIONS

Legumain and Smad3 expression is highly expressed in mainly atherosclerotic plaque macrophages and linearly related, which is attenuated by statin therapy, suggesting legumain a potential Smad3 pathway-related marker of atherosclerosis.