OXCT1 functions as a succinyltransferase, contributing to hepatocellular carcinoma via succinylating LACTB.

Metabolic reprogramming is an important feature of cancers that has been closely linked to post-translational protein modification (PTM). Lysine succinylation is a recently identified PTM involved in regulating protein functions, whereas its regulatory mechanism and possible roles in tumor progression remain unclear. Here, we show that OXCT1, an enzyme catalyzing ketone body oxidation, functions as a lysine succinyltransferase to contribute to tumor progression. Mechanistically, we find that OXCT1 functions as a succinyltransferase, with residue G424 essential for this activity. We also identified serine beta-lactamase-like protein (LACTB) as a main target of OXCT1-mediated succinylation. Extensive succinylation of LACTB K284 inhibits its proteolytic activity, resulting in increased mitochondrial membrane potential and respiration, ultimately leading to hepatocellular carcinoma (HCC) progression. In summary, this study establishes lysine succinyltransferase function of OXCT1 and highlights a link between HCC prognosis and LACTB K284 succinylation, suggesting a potentially valuable biomarker and therapeutic target for further development.

Circular RNA circ0104103 inhibits colorectal cancer progression through interactions with HuR and miR-373-5p.

Emerging evidence has suggested that circular RNAs (circRNAs) have vital functions during the initiation and progression of various diseases. However, circRNA potential mechanisms in colorectal cancer (CRC) are largely unknown. Here, we sought to investigate the role and underlying regulatory mechanism of circ0104103 in CRC. circ0104103 was validated by quantitative RT-PCR (qRT-PCR) and Sanger sequencing. Gain- and loss-of-function assays in cell lines and mouse xenograft models were utilized to investigate the effects of circ0104103 in CRC. RNA pull-down assays, RNA immunoprecipitation assays, bioinformatics analyses, RNA FISH, and luciferase reporter assays were used to elucidate the potential mechanism of circ0104103 in CRC. We identified circ0104103, which is strongly downregulated in CRC tissues and cell lines. Functional studies revealed that circ0104103 inhibited CRC cell growth, migration, and invasion both in vitro and in vivo. Mechanistically, circ0104103 binds to HuR, a functional RNA-binding protein commonly expressed in CRC. HuR binds to the 3'UTR of LACTB mRNA to facilitate stabilization and increase its expression. Moreover, circ0104103 was verified as a competing endogenous RNA (ceRNA) via negative regulation of miR-373-5p to increase LACTB expression, resulting in inhibiting the occurrence and progression of CRC. Taken together, our study revealed that circ0104103 acts as a tumor suppressor and may be a novel biomarker and therapeutic target in CRC.

LACTB induces cancer cell death through the activation of the intrinsic caspase-independent pathway in breast cancer.

BACKGROUND: LACTB was recently identified as a mitochondrial tumour suppressor that negatively affects cancer cell proliferation by inducing cell death and/or differentiation, depending on the cell type and tissue. However, the detailed mechanism underlying the LACTB-induced cancer cell death is largely unknown. METHODS: We used cell-based, either in 2D or 3D conditions, and in vivo experiments to understand the LACTB mechanisms. In this regard, protein array followed by an enrichment analysis, cell proliferation assays using different compounds, western blot analysis, flow cytometry and immunofluorescence were performed. Differences between quantitative variables following normal distribution were valuated using Student t test for paired or no-paired samples according to the experiment. For in vivo experiments differences in tumour growth were analyzed by 2-way ANOVA. RESULTS: We show, that LACTB expression leads to cell cycle arrest in G1 phase and increase of DNA oxidation that leads to activation of intrinsic caspase-independent cell death pathway. This is achieved by an increase of mitochondrial reactive oxygen species since early time points of LACTB induction. CONCLUSION: Our work provides a deeper mechanistic insight into LACTB-mediated cancer-cell death and shows the dynamics of the cellular responses a particular tumor suppressive stimulus might evoke under different genetic landscapes.

PCBP1 protects bladder cancer cells from mitochondria injury and ferroptosis by inducing LACTB mRNA degradation.

Although Poly C Binding Protein 1 (PCBP1) affects cellular ferroptosis and mitochondrial dysfunction, the mechanisms by which PCBP1 regulates bladder cancer (BC) cell functions are unknown. In this study, two BC cell lines (T24 and UMUC3) were treated with different doses of ferroptosis inducer erastin to analyze the effect of PCBP1. Online databases (RPISeq and CatRAPID) were used to predict the possible direct interaction between PCBP1 protein and serine ß-lactamase-like protein (LACTB) mRNA, which was further validated via RNA pull-down, RNA immunoprecipitation, and luciferase reporter assays. Mitochondria injury and ferroptosis were evaluated using CCK-8 assay, TUNEL staining, flow cytometry, corresponding kits, and JC-1 staining. In vivo experiments were conducted using tumor xenograft models. Quantitative reverse-transcription polymerase chain reaction was used to detect transcript expression levels, while protein levels were analyzed using western blot and immunohistochemistry. PCBP1 expression was significantly upregulated in BC tissues and cell lines. Also, PCBP1 knockdown increased erastin-mediated ferroptosis in T24 and UMUC3 cells, while PCBP1 overexpression decreased erastin-mediated ferroptosis in T24 and UMUC3 cells. Mechanistic results showed that LACTB mRNA is a novel PCBP1-binding transcript. LACTB upregulation promoted erastin-induced ferroptosis and mitochondrial dysfunction. Furthermore, LACTB overexpression reversed PCBP1-mediated ferroptosis protection, including decreased ROS and enhanced mitochondrial function, which were further alleviated after phosphatidylserine decarboxylase (PISD) overexpression. Moreover, PCBP1 silencing significantly enhanced tumor inhibition effect of sulfasalazine in xenograft mice transplanted with T24 and UMUC3 cells, leading to LACTB upregulation and PISD downregulation. In conclusion, PCBP1 protects BC cells against mitochondria injury and ferroptosis via LACTB/PISD axis.

Metabolic enzyme Suclg2 maintains tolerogenicity of regulatory dendritic cells diffDCs by suppressing Lactb succinylation.

Metabolic reprogramming plays a pivotal role in the differentiation and function of immune cells including dendritic cells (DCs). Regulatory DCs can be generated in regional tissue niches like splenic stroma and act as an important part of stromal control of immune response for the maintenance of immune tolerance. However, the metabolic alterations during splenic stroma-driven regulatory DCs differentiation and the metabolic enzyme involved in regulatory DCs function remain poorly understood. By combining metabolomic, transcriptomic, and functional investigations of mature DCs (maDCs) and diffDCs (regulatory DCs differentiated from activated mature DCs through coculturing with splenic stroma), here we identified succinate-CoA ligase subunit beta Suclg2 as a key metabolic enzyme that reprograms the proinflammatory status of mature DCs into a tolerogenic phenotype via preventing NF-κB signaling activation. diffDCs downregulate succinic acid levels and increase the Suclg2 expression along with their differentiation from mature DCs. Suclg2-interference impaired the tolerogenic function of diffDCs in inducing T cell apoptosis and enhanced activation of NF-κB signaling and expression of inflammatory genes CD40, Ccl5, and Il12b in diffDCs. Furthermore, we identified Lactb as a new positive regulator of NF-κB signaling in diffDCs whose succinylation at the lysine 288 residue was inhibited by Suclg2. Our study reveals that the metabolic enzyme Suclg2 is required to maintain the immunoregulatory function of diffDCs, adding mechanistic insights into the metabolic regulation of DC-based immunity and tolerance.

LACTB suppresses migration and invasion of glioblastoma via downregulating RHOC/Cofilin signaling pathway.

Glioblastoma (GBM) is the most malignant tumor in human brain. High invasiveness of this tumor is the main reason causing treatment failure and recurrence. Previous study has found that LACTB is a novel tumor suppressor in breast cancer. Moreover, the function of LACTB in other tumors and mechanisms involving LACTB were also reported. However, the role and relevant mechanisms of LACTB in GBM invasion remains to be revealed. Our aim is to investigate the role LACTB in GBM migration and invasion. We found that LACTB was downregulated in gliomas compared to normal brain tissues. Overexpression of LACTB suppressed migration and invasion of LN229 and U87 cell lines. Mechanistically, LACTB overexpression downregulated the mesenchymal markers. Moreover, LACTB overexpression downregulated the expression of RHOC and inhibited RHOC/Cofilin signaling pathway. The study suggests that LACTB suppresses migration and invasion of GBM cell lines via downregulating RHOC/Cofilin signaling pathway. These findings suggest that LACTB may be a potential treatment target of GBM.

Deciphering balanced translocations in infertile males by next-generation sequencing to identify candidate genes for spermatogenesis disorders.

Male infertility affects about 7% of the general male population. Balanced structural chromosomal rearrangements are observed in 0.4-1.4% of infertile males and are considered as a well-established cause of infertility. However, underlying pathophysiological mechanisms still need to be clarified. A strategy combining standard and high throughput cytogenetic and molecular technologies was applied in order to identify the candidate genes that might be implicated in the spermatogenesis defect in three male carriers of different balanced translocations. Fluorescence in situ hybridization (FISH) and whole-genome paired-end sequencing were used to characterize translocation breakpoints at the molecular level while exome sequencing was performed in order to exclude the presence of any molecular event independent from the chromosomal rearrangement in the patients. All translocation breakpoints were characterized in the three patients. We identified four variants: a position effect on LACTB2 gene in Patient 1, a heterozygous CTDP1 gene disruption in Patient 2, two single-nucleotide variations (SNVs) in DNAH5 gene and a heterozygous 17q12 deletion in Patient 3. The variants identified in this study need further validation to assess their roles in male infertility. This study shows that beside the mechanical effect of structural rearrangement on meiosis, breakpoints could result in additional alterations such as gene disruption or position effect. Moreover, additional SNVs or copy number variations may be fortuitously present and could explain the variable impact of chromosomal rearrangements on spermatogenesis. In conclusion, this study confirms the relevance of combining different cytogenetic and molecular techniques to investigate patients with spermatogenesis disorders and structural rearrangements on genomic scale.

MicroRNA-125b-5p attenuates lipopolysaccharide-induced monocyte chemoattractant protein-1 production by targeting inhibiting LACTB in THP-1 macrophages.

BACKGROUND: Increasing evidence has shown that gene beta-lactamases (LACTB) has effect on obesity. Recent studies demonstrate that miR-125b-5p is a potential small molecular target to prevent atherosclerosis obliterans which may be inflammation-associated. However, the mechanism underlying miR-125b-5p on arteriosclerosis development, the association between miR-125b-5p and LACTB is still unknown. METHODS AND RESULTS: In this study, we found that miR-125b-5p was down-regulated while LACTB was up-regulated in atherosclerotic plaques. Our results showed that LACTB was a potential target of miR-125b-5p based on bioinformatics analyses and dual-luciferase reporter assays. Moreover, miR-125b-5p directly inhibited LACTB protein and mRNA expression by targeting LACTB 3'UTR. Meanwhile, the expression of monocyte chemotactic protein-1 (MCP-1) was decreased by miR-125b-5p mimics treatment in THP-1 macrophages. We also demonstrated that the level of MCP-1 was markedly increased when transfected with LACTB. In addition, the upregulation of MCP-1 expression through miR-125b-5p inhibitors was attenuate by siRNA-LACTB treatment in LPS-stimulated THP-1 macrophages. CONCLUSIONS: MiR-125b-5p attenuates the secretion of MCP-1 by directly targeting inhibiting LACTB in LPS-stimulated THP-1 macrophages.

SNPs Give LACTB Oncogene-Like Functions and Prompt Tumor Progression via Dual-Regulating p53.

LACTB is identified as a tumor suppressor in several tumors. However, preliminary study reveals that LACTB is overexpressed in osteosarcoma and indicates poor prognosis. Two missense mutations (rs34317102 and rs2729835) exist simultaneously in 92.31% of osteosarcoma patients and cause M5L and R469K double mutations in LACTB, suggesting the biologic function of LACTB protein may be altered in osteosarcoma. Moreover, LACTBM5L+R469K overexpression can promote malignant progression in different tumors, which suggests that the M5L and R469K mutations confer oncogene-like functions to LACTB. Mechanistically, LACTBM5L+R469K not only reduces the wild type p53 via enhancing PSMB7 catalytic activity, but also protects p53R156P protein from lysosomal degradation, which suggesting LACTBM5L+R469K is a dual-regulator for wt-p53 and mutant p53, and derive oncogene-like functions. More importantly, clavulanate potassium, a bacterial ß-lactamase inhibitor, can inhibit osteosarcoma proliferation and sensitize osteosarcoma to cisplatin by binding and blocking LACTBM5L+R469K. These findings revealed that the M5L and R469K double mutations can diminish the tumor suppressive ability of wild type LACTB and provide oncogene-like functions to LACTB. Inhibiting LACTBM5L+R469K can suppress the progression of osteosarcoma harbouring wild-type or mutant p53. Clavulanate potassium is a promising drug by targeting LACTBM5L+R469K-p53 pathway for the treatment of osteosarcoma patients.

LACTB suppresses liver cancer progression through regulation of ferroptosis.

Ferroptosis, driven by iron-dependent phospholipid peroxidation, is emerging as an intrinsic cancer defense mechanism. However, the regulatory networks involved in ferroptosis remain largely unknown. Here, we found that serine beta-lactamase-like protein (LACTB) inhibits liver cancer progression by regulating ferroptosis. LACTB is downregulated in liver cancer, and the ectopic expression of LACTB markedly inhibits cell viability, colony formation, and tumour growth. LACTB knockout exerts the opposite effects. Further investigation revealed that LACTB blocks HSPA8 transcription in a p53-dependent manner, resulting in the elevation of NCOA4-mediated ferritinophagy and inhibition of SLC7A11/GSH/GPX4 signalling, thereby triggering ferroptosis and suppressing liver cancer progression. Liver cancer cells with an endogenous mutation of p53 binding site in the HSPA8 promoter exhibited increased resistance to ferroptosis inducers, and the ferroptosis-promoting effect of LACTB was significantly weakened in these mutant cells. Importantly, LACTB is identified as a downstream target of lenvatinib, and adeno-associated virus-mediated overexpression and knockdown of LACTB notably enhance and attenuate the anti-tumour efficacy of lenvatinib in vivo, respectively. Taken together, our study reveals a novel action of LACTB and provides potential therapeutic strategies for enhancing the efficacy of lenvatinib in liver cancer.

Identification of the prognostic value of LACTB2 and its correlation with immune infiltrates in ovarian cancer by integrated bioinformatics analyses.

Ovarian cancer (OC) is one of the most common reproductive tumors in women, whereas current treatment options are limited. ß-lactamase-like-protein 2 (LACTB2) has been observed to be associated with various cancers, but its function in OC is unknown. Therefore, we evaluate the prognostic value and the underlying function of LACTB2 in OC. In this study, high expression of LACTB2 was observed in OC compared with normal controls. Kaplan-Meier Plotter analysis revealed that overexpressed LACTB2 is strongly correlated with poor prognosis. We conducted GO/KEGG analysis to investigate the potential biological function of LACTB2 in OC. GESA analysis showed that LACTB2 was closely related to immune-related pathways. Subsequently, we explored the relationship between LACTB2 and 24 types of immune cells in OC. The results suggested that LACTB2 was positively associated with multiple tumor-infiltrating immune cells. Importantly, LACTB2 may modulate immune cell infiltration in OC to influence prognosis. In conclusion, LACTB2 can be used as a promising prognostic biomarker and immunotherapy target for OC.

Increased LACTB2 Expression Regulates Oxidative Phosphorylation and mTORC1 Signaling of Colorectal Cancer.

This study aimed to investigate the mechanisms of LACTB2 in colorectal cancer (CRC). Microarrays and sequencing data of CRC were acquired from UCSC Xena, GTEx, Gene Expression Omnibus, and TCGA. Pooled analysis of the mRNA expression of LACTB2 in CRC was performed using Stata software. The protein expression of LACTB2 in CRC tissues was evaluated by immunohistochemistry. The relationship between immune cell infiltration and LACTB2 expression was investigated using CIBERSORT. The potential signaling pathways and biological mechanisms of LACTB2 were explored using GSEA, KEGG, and GO. Subsequently, further screening of small molecular compounds with potential therapeutic effects on CRC was conducted through the HERB database, followed by molecular docking studies of these compounds with the LACTB2 protein. The integration and analysis of expression data obtained from 2294 CRC samples and 1286 noncancerous colorectal samples showed that LACTB2 was highly expressed in CRC. Immunohistochemistry performed on in-house tissue samples confirmed that LACTB2 protein expression was upregulated in CRC. CIBERSORT revealed lower B cell infiltration levels in the high LACTB2 expression group than in the low expression group. GO, KEGG, and GSEA analyses showed that LACTB2 expression and genes positively correlating with it were mainly related to DNA synthesis and repair, mitochondrial translational elongation and translational termination, phosphorylation, and mTORC1 signaling. Finally, molecular docking simulations confirmed the ability of quercitin to target and bind to LACTB2. This is the first study to demonstrate that LACTB2 is upregulated in CRC. LACTB2 promotes colorectal tumorigenesis and tumor progression.

A potential therapeutic approach for gastric cancer: inhibition of LACTB transcript 1.

BACKGROUND: This study sought to investigate the role of LACTB transcript 1 in regulating adaptive immune resistance and stemness in gastric cancer and its potential as a therapeutic target for precision medicine. METHODS: Bioinformatics analysis and RT-qPCR were used to analyze the expression level of LACTB and its transcripts in gastric cancer cells. The effects of LACTB transcript 1 on adaptive immune resistance and stemness were evaluated using in vitro cell experiments and western blotting experiments. RESULTS: Our study findings revealed that LACTB transcript 1 modulated adaptive immune resistance and inhibited the stemness of gastric cancer cells. Knocking down the expression level of LACTB transcript 1 activated autophagy and inhibited EMT. As expected, overexpression of LACTB transcript 1 yielded the opposite findings. The expression level of LACTB transcript 1 in the peripheral blood of gastric cancer patients was consistent with the bioinformatics analysis, suggesting its potential as a biomarker of gastric cancer. CONCLUSIONS: LACTB transcript 1 is a promising therapeutic target for precision medicine in gastric cancer by modulating immune evasion mechanisms and stemness. These findings provide insights into leveraging long non-coding RNAs (lncRNAs) in immunotherapy, radiotherapy, and chemotherapy to enhance cancer therapy efficacy, particularly in the context of targeting tumor heterogeneity and stemness.

Unveiling the Function of the Mitochondrial Filament-Forming Protein LACTB in Lipid Metabolism and Cancer.

LACTB is a relatively unknown mitochondrial protein structurally related to the bacterial penicillin-binding and beta-lactamase superfamily of serine proteases. LACTB has recently gained an increased interest due to its potential role in lipid metabolism and tumorigenesis. To date, around ninety studies pertaining to LACTB have been published, but the exact biochemical and cell biological function of LACTB still remain elusive. In this review, we summarise the current knowledge about LACTB with particular attention to the implications of the recently published study on the cryo-electron microscopy structure of the filamentous form of LACTB. From this and other studies, several specific properties of LACTB emerge, suggesting that the protein has distinct functions in different physiological settings. Resolving these issues by further research may ultimately lead to a unified model of LACTB's function in cell and organismal physiology. LACTB is the only member of its protein family in higher animals and LACTB may, therefore, be of particular interest for future drug targeting initiatives.

Clinical Significance of ß-Lactamase Expression in Colorectal Cancer.

Background: Colorectal cancer (CRC) has seriously endangered human health. Despite significant advances in clinical treatment of CRC in recent years, clinically effective treatment options for CRC patients remain rare. Therefore, reducing the incidence and mortality of CRC is still a worldwide concern. This study aims to explore the clinical significance of lactamase beta (LACTB)-like expression in CRC tissues. Materials and Methods: The expression of LACTB in CRC tissues and adjacent tissues in The Cancer Genome Atlas database was analyzed and the analysis results were verified by immunohistochemistry. The correlation between the expression level of LACTB and pathological factors and prognosis was analyzed. Results: There was statistical difference in the expression of LACTB in CRC tissues and adjacent tissues (p < 0.01). The expression of LACTB in CRC tissues was correlated with clinical stage (p < 0.01). The expression of LACTB in CRC patients with lymph node metastasis was significantly lower than that in CRC patients without lymph node metastasis (p < 0.01). Low expression of LACTB contributed to the poor prognosis of CRC patients. The 5-year survival rate of CRC patients with low LACTB expression was significantly lower than that of CRC patients with high LACTB expression (p = 0.010, p = 0.047). Conclusions: The expression of LACTB in CRC tissues was significantly lower than that in normal tissues, and it was significantly correlated with clinical prognosis, suggesting that LACTB could inhibit the CRC invasion and metastasis. This indicated to some extent that LACTB could be used as a prognostic marker and a new therapeutic target for CRC.

LACTB suppresses carcinogenesis in lung cancer and regulates the EMT pathway.

Lung cancer causes thousands of deaths worldwide every year, and present therapeutics show little benefit for advanced-stage patients. Researchers do not know why and how lung cancer begins. Lactamase ß (LACTB) is a tumor-suppressor in some cancers. However, its role in lung cancer is unknown. By analyzing the TCGA database and Kaplan-Meier Plotter database, LACTB was found to be downregulated in lung cancer tissues but the methylation level was increased. Patients with high LACTB expression exhibited improved survival. Then, in vitro assays demonstrated that LACTB overexpression inhibited cell migration and invasion, and induced apoptosis in H1299 and H1975 cells. Knockdown of LACTB caused the reverse effects. Moreover, a much higher apoptotic rate and more potent inhibitory effects on H1299 and H1975 cells were obtained when LACTB was combined with docetaxel. In addition, members of the epithelial-mesenchymal transition (EMT) signaling pathway were assessed using western blot analysis. The expression of E-cadherin was decreased while levels of N-cadherin and vimentin were increased after knockdown of LACTB in lung cancer cells. By contrast, overexpression of LACTB increased the level of E-cadherin but decreased N-cadherin and vimentin. Therefore, LACTB is a tumor suppressor in lung cancer that inhibits cell migration and invasion and induces cell apoptosis. Meanwhile, LACTB was found to strengthen the anticancer role of docetaxel and to suppress the EMT pathway in lung cancer.

Structural basis for the catalytic activity of filamentous human serine beta-lactamase-like protein LACTB.

Serine beta-lactamase-like protein (LACTB) is a mammalian mitochondrial serine protease that can specifically hydrolyze peptide bonds adjacent to aspartic acid residues and is structurally related to prokaryotic penicillin-binding proteins. Here, we determined the cryoelectron microscopy structures of human LACTB (hLACTB) filaments from wild-type protein, a middle region deletion mutant, and in complex with the inhibitor Z-AAD-CMK at 3.0-, 3.1-, and 2.8-Å resolution, respectively. Structural analysis and activity assays revealed that three interfaces are required for the assembly of hLACTB filaments and that the formation of higher order helical structures facilitates its cleavage activity. Further structural and enzymatic analyses of middle region deletion constructs indicated that, while this region is necessary for substrate hydrolysis, it is not required for filament formation. Moreover, the inhibitor-bound structure showed that hLACTB may cleave peptide bonds adjacent to aspartic acid residues. These findings provide the structural basis underlying hLACTB catalytic activity.

Pinocembrin Inhibits the Proliferation, Migration, Invasiveness, and Epithelial-Mesenchymal Transition of Colorectal Cancer Cells by Regulating LACTB.

Background: Colorectal cancer (CRC) is a common malignancy of digestive tract. Pinocembrin (PINO) has been discovered to have a proapoptotic effect on CRC. This study aimed to elucidate how other biological behaviors of CRC cells were affected under PINO treatment. Materials and Methods: The effect of PINO on HT29 and HCT116 cells were detected through treatment of different concentrations of PINO. The role of LACTB in PINO treatment was investigated by transfection of siRNA-LACTB. Cell counting kit-8 assay, wound healing assay, and Transwell assay were conducted to evaluate the proliferation, migration, and invasiveness of CRC cells, respectively. Western blot or quantitative reverse transcription-polymerase chain reaction was carried out to measure the expressions of LACTB, matrix metalloproteinase (MMP)-2, E-cadherin, and N-cadherin. Results: Gradient PINO inhibited the viability, migration, invasiveness, and expressions of MMP-2 and N-cadherin in CRC cells, while promoted E-cadherin and LACTB expressions. Silencing LACTB promoted the viability, migration, invasiveness, and expressions of MMP-2 and N-cadherin in CRC cells and inhibited E-cadherin expression. PINO counteracted the effect of silenced LACTB, and yet silencing LACTB partially abolished the effect of PINO on CRC cells. Conclusion: PINO inhibited the proliferation, migration, invasiveness, and epithelial-to-mesenchymal transition of CRC cells by regulating LACTB.

Targeted Nanotherapeutics Using LACTB Gene Therapy Against Melanoma.

INTRODUCTION: ß-lactamase (LACTB) is a tumor suppressor gene in various tumors including melanoma. However, it remains challenging to efficiently deliver the LACTB gene into melanoma. Recently, we designed a nonviral nanocarrier iRGD/DOTAP/MPEG-PDLLA (iDPP) that could deliver gene targetedly to melanoma efficiently without obvious adverse effects. METHODS: In this study, the tumor-targeted nanoparticle iDPP was prepared to deliver LACTB gene to treat melanoma in vitro and in vivo. First, the expression level of LACTB in 6 clinical specimens of melanoma patients was evaluated. Subsequently, the characteristics of iDPP/LACTB nanocomplexes were studied. Afterwards, the in vitro and in vivo anti-tumor efficacy of the iDPP/LACTB nanocomplexes were explored utilizing the B16-F10 mouse melanoma cell line and the B16-F10 subcutaneous melanoma model. RESULTS: Compared with the normal epithelium, the expression level of LACTB in melanoma tissues was significantly downregulated. In vitro B16-F10 cell tests showed iDPP/LACTB nanocomplexes could increase the mRNA levels of P21, Bid, Bax, Pidd1, and Sival genes and up-regulate the p53 signaling pathway of melanoma cells, thus promoting cell apoptosis and blocking the cell cycle. Injected intravenously, iDPP nanoparticles could deliver DNA to the subcutaneous melanoma targetedly. Based on in vivo mouse xenograft model, iDPP/LACTB nanocomplexes could effectively inhibit tumor proliferation and induce tumor apoptosis, thus significantly inhibiting melanoma growth (tumor inhibition rate is about 68%) in the subcutaneous B16-F10 melanoma model. CONCLUSION: The downregulated LACTB might be a potential target for melanoma therapy. The iDPP/LACTB nanocomplexes could inhibit the growth of the mouse melanoma without obvious side effects, which provide a new option for melanoma gene therapy research.

LACTB2 renders radioresistance by activating PINK1/Parkin-dependent mitophagy in nasopharyngeal carcinoma.

Radiotherapy is a standard and conventional treatment strategy for nasopharyngeal carcinoma (NPC); however, radioresistance remains refractory to clinical outcomes. Understanding the molecular mechanism of radioresistance is crucial for advancing the efficacy of radiotherapy and improving the prognosis of NPC. In this study, ß-lactamase-like-protein 2 (LACTB2) was identified as a potential biomarker for radioresistance using tandem mass tag proteomic analysis of NPC cells, gene chip analysis of NPC tissues, and differential gene analysis between NPC and normal nasopharyngeal tissues from the Gene Expression Omnibus database GSE68799. Meanwhile, LACTB2 levels were elevated in the serum of patients with NPC after radiotherapy. Inhibiting LACTB2 levels and mitophagy can sensitize NPC cells to ionizing radiation. In NPC cells, LACTB2 was augmented at the transcription and protein levels after radiation rather than nucleus-cytoplasm-mitochondria transposition to activate PTEN-induced kinase 1 (PINK1) and mitophagy. In addition, LACTB2 was first authenticated to co-locate with PINK1 by interacting with its N-terminal domain. Together, our findings indicate that overexpressed LACTB2 provoked PINK1-dependent mitophagy to promote radioresistance and thus might serve as a prognostic biomarker for NPC radiotherapy.