The laminin family: founding members of the basement membrane

Lama1 upregulation prolongs the lifespan of the dyH/dyH mouse model of LAMA2-related congenital muscular dystrophy

LAMA2-related congenital muscular dystrophy (LAMA2-CMD), characterized by laminin-α2 deficiency, is debilitating and ultimately fatal. To date, no effective therapy has been clinically available. Laminin-α1, which shares significant similarities with laminin-α2, has been proven as a viable compensatory modifier. To evaluate its clinical applicability, we establish a Lama2 exon-3-deletion mouse model (dyH/dyH). The dyH/dyH mice exhibit early lethality and typical LAMA2-CMD phenotypes, allowing the evaluation of various endpoints. In dyH/dyH mice treated with synergistic activation mediator-based CRISPRa-mediated Lama1 upregulation, a nearly doubled median survival is observed, as well as improvements in weight and grip. Significant therapeutical effects are revealed by MRI, serum biochemical indices, and muscle pathology studies. Treating LAMA2-CMD with LAMA1 upregulation is feasible, and early intervention can alleviate symptoms and extend lifespan. Additionally, we reveal the limitations of LAMA1 upregulation, including high-dose mortality and non-sustained expression, which require further optimization in future studies.

EPRS1 correlates with malignant progression in hepatocellular carcinoma

BACKGROUND

Glutamyl-prolyl-tRNA synthetase 1 (EPRS1) is an aminoacyl-tRNA synthase involved in the pathology of cancer and other diseases. In this study, we investigated the carcinogenic function, potential mechanism, and clinical significance of EPRS1 in human hepatocellular carcinoma (HCC).

METHODS

The expression, clinical significance, and prognostic value of EPRS1 in HCC were assessed using the TCGA and GEO databases. The function of EPRS1 in HCC cells was detected by CCK-8, Transwell, and hepatosphere formation assays. Immunohistochemistry was used to explore the difference in EPRS1 levels in HCC tissues and peri-cancerous tissues. The mechanism of EPRS1 was studied using a proteomics method. Finally, cBioportal and MEXEPRSS were used to analyze the variations involved in the differential expression of EPRS1.

RESULTS

EPRS1 was frequently upregulated at the mRNA and protein levels in liver cancer. Increased EPRS1 correlated with shortened patient survival. EPRS1 could promote cancer cell proliferation, characteristics of cell stemness, and mobility. Mechanistically, EPRS1 played a carcinogenic role by upregulating several downstream proline-rich proteins, primarily LAMC1 and CCNB1. In addition, copy number variation could contribute to the high expression of EPRS1 in liver cancer.

CONCLUSION

Together, our data imply that enhanced EPRS1 contributes to the development of HCC by increasing the expression of oncogenes in the tumor microenvironment. EPRS1 may be a successful treatment target.

RNA helicase DDX24 stabilizes LAMB1 to promote hepatocellular carcinoma progression

Hepatocellular carcinoma (HCC) is one of the most aggressive malignancies. Elucidating the underlying mechanisms of this disease could provide new therapeutic strategies for treating HCC. Here, we identified a novel role of DEAD-box helicase 24 (DDX24), a member of the DEAD-box protein family, in promoting HCC progression. DDX24 levels were significantly elevated in HCC tissues and were associated with poor prognosis of HCC. Overexpression of DDX24 promoted HCC migration and proliferation in vitro and in vivo, whereas suppression of DDX24 inhibited both functions. Mechanistically, DDX24 bound the mRNA618-624nt of laminin subunit beta 1 (LAMB1) and increased its stability in a manner dependent upon the interaction between nucleolin (NCL) and the C-terminal region of DDX24. Moreover, RFX8 was identified as a DDX24 promoter-binding protein that transcriptionally upregulated DDX24 expression. Collectively, these findings demonstrate that the RFX8/DDX24/LAMB1 axis promotes HCC progression, providing potential therapeutic targets for HCC.

Fuchs Endothelial Corneal Dystrophy associated risk variant, rs3768617 in LAMC1 shows allele specific binding of GFI1B

AIMS

To investigate the genetic and functional association of an intronic variant of LAMC1, rs3768617 with Fuchs endothelial corneal dystrophy (FECD) in the Indian population.

METHODS

Blood samples were collected from age and sex matched 356 controls and 120 FECD patients after a detailed assessment via specular microscopy. Genomic DNA was extracted and genotyping was done by fluorescence based capillary electrophoresis. The genetic association of rs3768617 polymorphisms was computed by the chi-square (χ²) test. Bioinformatics studies were performed to find the allele specific binding of different transcription factors in the region of rs3768617 and functional evaluation assessed by luciferase assay followed by Electrophoretic Mobility Shift Assay (EMSA) and Chromatin Immunoprecipitation assay (ChIP). Immunofluorescence assay was carried out to check for any differential expression of GFI1B between control and FECD endothelium samples.

RESULTS

SNP rs3768617 {chr1:183123365 (GRCh38.p13)} was found to be genetically associated with FECD in Indian population (p = 2.646 × 10^-8). Luciferase assay suggested that the rs3768617 locus has a regulatory role. In silico analysis showed that the transcription factor, GFI1B binds to the risk allele 'G' of rs3768617, but not to the protective allele 'A' which was also experimentally validated by EMSA. High enrichment of DNA flanking the surrounding region of rs3768617 was also found in presence of GFI1B specific antibody in ChIP assay. There was a 0.63 fold decrease in GFI1B expression in FECD affected corneal endothelium compared to control endothelium.

CONCLUSIONS

The genetic association of rs3768617 in LAMC1 with FECD pathogenesis is mediated by GFI1B, thus finding the functional role of LAMC1 in FECD pathogenesis.

A novel regQTL-SNP and the risk of lung cancer: a multi-dimensional study

RegQTL, a novel concept, indicates that different genotypes of some SNPs have differential effects on the expression patterns of miRNAs and their target mRNAs. We aimed to identify the association between regQTL-SNPs and lung cancer risk and to explore the underlying mechanisms. The two-stage case-control study included the first stage in a Chinese population (626 lung cancer cases and 667 healthy controls) and the second stage in a European population (18,082 lung cancer cases and 13,780 healthy controls). Functional annotations were conducted based on the GTEx and the TCGA databases. Functional experiments were performed to explore the underlying biological mechanisms in vitro and vivo. After strict screening, five candidate regQTL-SNPs (rs7110737, rs273957, rs6593210, rs3768617, and rs6836432) were selected. Among them, the variant T allele of rs3768617 in LAMC1 was found to significantly increase the risk of lung cancer (first stage: P = 0.044; second stage: P = 0.007). The eQTL analysis showed that LAMC1 expression level was significantly higher in subjects with the variant T allele of rs3768617 (P = 1.10 × 10^-14). In TCGA paired database, the regQTL annotation indicated the different expression patterns between LAMC1 and miRNA-548b-3p for the distinct genotypes of rs3768617. Additionally, LAMC1 knockdown significantly inhibited malignant phenotypes in lung cancer cell lines and suppressed tumor growth. A novel regQTL-SNP, rs3768617, might affect lung cancer risk by modulating the expression patterns of miRNA-548b-3p and LAMC1. RegQTL-SNPs could provide a new perspective for evaluating the regulatory function of SNPs in lung cancer development.

Lamc1 promotes the Warburg effect in hepatocellular carcinoma cells by regulating PKM2 expression through AKT pathway

Hepatocellular carcinoma (HCC), the most common aggressive malignancy of liver, is the third leading cause of cancer death across the world. Laminin gamma 1 (Lamc1), encodes laminin-γ1, an extracellular matrix protein involved in various progresses such as tumor cell proliferation and metabolism. In the present study, high expression of Lamc1 and PKM2 was observed in tumor tissues of HCC patients. In vitro, down-regulation of Lamc1 inhibited proliferation of HCC cells by promoting cell death, reduced glucose consumption and lactate production, accompanied by a decrease in the expression of glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA), and PTEN increased, as well as PTEN S380 and AKT S473/T308 phosphorylation decreased, while Lamc1 up-regulation had the opposite effect. The effects of PKM2 were similar to that of Lamc1 and markedly counteracted the effects of Lamc1 down-regulation. In addition, Lamc1-induced increase in PKM2 expression was strongly attenuated by a PI3K inhibitor, LY294002 or a si-p110 PI3K, with a significant decrease in GLUT1 and LDHA expression, as well as decreased AKT T308 phosphorylation. Thus, we speculated that Lamc1 was implicated in the progression of HCC probably by regulating PKM2 expression through PTEN/AKT pathway.

Human Placenta Laminin-111 as a Multifunctional Protein for Tissue Engineering and Regenerative Medicine

Laminins are major components of all basement membranes surrounding nerve or vascular tissues. In particular laminin-111, the prototype of the family, facilitates a large spectrum of fundamental cellular responses in all eukaryotic cells. Laminin-111 is a biomaterial frequently used in research, however it is primarily isolated from non-human origin or produced with time-intensive recombinant techniques at low yield.Here, we describe an effective method for isolating laminin-111 from human placenta, a clinical waste material, for various tissue engineering applications. By extraction with Tris-NaCl buffer combined with non-protein-denaturation ammonium sulfate precipitation and rapid tangential flow filtration steps, we could effectively isolate native laminin-111 within only 4 days. The resulting material was biochemically characterized using a combination of dot blot, SDS-PAGE, Western blot and HPLC-based amino acid analysis. Cytocompatibility studies demonstrated that the isolated laminin-111 promotes rapid and efficient adhesion of primary Schwann cells. In addition, the bioactivity of the isolated laminin-111 was demonstrated by (a) using the material as a substrate for outgrowth of NG 108-15 neuronal cell lines and (b) promoting the formation of interconnected vascular networks by GFP-expressing human umbilical vein endothelial cells.In summary, the isolation procedure of laminin-111 as described here from human placenta tissue, fulfills many demands for various tissue engineering and regenerative medicine approaches and therefore may represent a human alternative to various classically used xenogenic standard materials.

The association of LAMB1 polymorphism and expression changes with the risk of coal workers' pneumoconiosis

BACKGROUND

Pneumoconiosis is a serious occupational disease worldwide, which is characterized by irreversible and diffuse lung fibrotic lesions. Laminin beta 1(LAMB1) is widely expressed in tissues and it is crucial for both lung morphogenesis and physiological function. In this study, we explored the association between LAMB1 rs4320486 and risk of pneumoconiosis in a Chinese population, as well as its mechanisms.

METHODS

In this case-control study, 600 CWP patients and 605 controls were genotyped for the LAMB1 rs4320486 polymorphism using TaqMan methods. Luciferase reporter assay was used to assess the LAMB1 transcriptional activities. The protein levels in cells and tissues were detected by western blot, and mRNA levels were determined by qRT-PCR.

RESULTS

Logistic regression analysis revealed that individuals with LAMB1 rs4320486 CT/TT genotypes had a significantly decreased risk of CWP (adjusted OR = 0.78, 95%CI = 0.64-0.94), compared with individuals with CC genotypes. Luciferase assays showed that the LAMB1 rs4320486(C > T) substitution could decrease the expression of LAMB1. Compared with normal groups, mRNA levels of LAMB1 were up-regulated in lung tissues of patients with pulmonary fibrosis. Additionally, expressions of LAMB1 and α-SMA were enhanced progressively, along with the development of lung fibrosis, while E-cadherin decreased.

CONCLUSIONS

In this study, the functional LAMB1 rs4320486 mutation was associated with a decreased risk of CWP in a Chinese population, probably owing to the reduced activity of LAMB1 transcription. LAMB1 expression was increased in the progress of lung fibrosis, which suggests that LAMB1 may affect the initiation and progression of pneumoconiosis, or serve as a potential biomarker of pneumoconiosis for diagnosis and genetic susceptibility.

Overexpression of LAMC1 predicts poor prognosis and enhances tumor cell invasion and migration in hepatocellular carcinoma

LAMC1 encodes an extracellular matrix protein, laminin γ1 chain, which is involved in several biological and pathological processes including tissue development, tumor cell invasion and metastasis. In present study, we demonstrated that both LAMC1 protein and mRNA levels were elevated in HCC tissue samples compared with non-cancerous tissue samples according to western blot analyses, immunohistochemistry (IHC) and microarray. Moreover, high LAMC1 expression was positively correlated with incomplete encapsulation (p=0.014), poor overall (OS, p=0.02) and disease-free survival (DFS, p=0.014). Using cell lines, we demonstrated that the levels of LAMC1 mRNA and protein were significantly higher in HCC cell lines than that in LO2 cell line. After the expression of LAMC1 was depressed by siRNA technique, the cell proliferation, migration and invasion were depressed significantly. Taken together, these data suggest that LAMC1 is enriched in HCC; overexpression of LAMC1 predicts poor prognosis, and enhances tumor cell invasion and migration. LAMC1 might be a new biomarker predictive of HCC prognosis and might also be a useful treatment target.

The laminin response in inflammatory bowel disease: protection or malignancy?

Laminins (LM), basement membrane molecules and mediators of epithelial-stromal communication, are crucial in tissue homeostasis. Inflammatory Bowel Diseases (IBD) are multifactorial pathologies where the microenvironment and in particular LM play an important yet poorly understood role in tissue maintenance, and in cancer progression which represents an inherent risk of IBD. Here we showed first that in human IBD colonic samples and in murine colitis the LMα1 and LMα5 chains are specifically and ectopically overexpressed with a concomitant nuclear p53 accumulation. Linked to this observation, we provided a mechanism showing that p53 induces LMα1 expression at the promoter level by ChIP analysis and this was confirmed by knockdown in cell transfection experiments. To mimic the human disease, we induced colitis and colitis-associated cancer by chemical treatment (DSS) combined or not with a carcinogen (AOM) in transgenic mice overexpressing LMα1 or LMα5 specifically in the intestine. We demonstrated that high LMα1 or LMα5 expression decreased susceptibility towards experimentally DSS-induced colon inflammation as assessed by histological scoring and decrease of pro-inflammatory cytokines. Yet in a pro-oncogenic context, we showed that LM would favor tumorigenesis as revealed by enhanced tumor lesion formation in both LM transgenic mice. Altogether, our results showed that nuclear p53 and associated overexpression of LMα1 and LMα5 protect tissue from inflammation. But in a mutation setting, the same LM molecules favor progression of IBD into colitis-associated cancer. Our transgenic mice represent attractive new models to acquire knowledge about the paradoxical effect of LM that mediate either tissue reparation or cancer according to the microenvironment. In the early phases of IBD, reinforcing basement membrane stability/organization could be a promising therapeutic approach.