37 kDa LRP::FLAG enhances telomerase activity and reduces senescent markers in vitro

PLGA nanocapsules as a delivery system for a recombinant LRP-based therapeutic

Telomerase activity is directly affected by the laminin receptor precursor (LRP) protein, a highly conserved nonintegrin transmembrane receptor, which has been shown to have therapeutic effects in ageing, and age-related diseases. Recently, it has been found that overexpression of LRP-FLAG, by plasmid transfection, leads to a significant increase in telomerase activity in cell culture models. This may indicate that upregulation of LRP can be used to treat various age-related diseases. However, transfection is not a viable treatment strategy for patients. Therefore, we present a nanoencapsulated protein-based drug synthesised using poly(lactic-co-glycolic acid) (PLGA) nanocapsules for delivery of the 37 kDa LRP protein therapeutic. PLGA nanocapsules were synthesised using the double emulsification-solvent evaporation technique. Different purification methods, including filtration and centrifugation, were tested to ensure that the nanocapsules were within the optimal size range, and the BCA assay was used to determine encapsulation efficiency. The completed drug was tested in a HEK-293 cell culture model, to investigate the effect on cell viability, LRP protein levels and telomerase activity. A significant increase in total LRP protein levels with a concomitant increase in cell viability and telomerase activity was observed. Due to the observed increase in telomerase activity, this approach could represent a safer alternative to plasmid transfection for the treatment of age-related diseases.

Emerging roles of the cellular prion protein (PrPC) and 37/67 kDa laminin receptor (RPSA) interaction in cancer biology

The cellular prion protein (PrPC) is well-known for its involvement, under its pathogenic protease-resistant form (PrPSc), in a group of neurodegenerative diseases, known as prion diseases. PrPC is expressed in nervous system, as well as in other peripheral organs, and has been found overexpressed in several types of solid tumors. Notwithstanding, studies in recent years have disclosed an emerging role for PrPC in various cancer associated processes. PrPC has high binding affinity for 37/67 kDa laminin receptor (RPSA), a molecule that acts as a key player in tumorigenesis, affecting cell growth, adhesion, migration, invasion and cell death processes. Recently, we have characterized at cellular level, small molecules able to antagonize the direct PrPC binding to RPSA and their intracellular trafficking. These findings are very crucial considering that the main function of RPSA is to modulate key events in the metastasis cascade. Elucidation of the role played by PrPC/RPSA interaction in regulating tumor development, progression and response to treatment, represents a very promising challenge to gain pathogenetic information and discover novel specific biomarkers and/or therapeutic targets to be exploited in clinical settings. This review attempts to convey a detailed description of the complexity surrounding these multifaceted proteins from the perspective of cancer hallmarks, but with a specific focus on the role of their interaction in the control of proliferation, migration and invasion, genome instability and mutation, as well as resistance to cell death controlled by autophagic pathway.

Downregulation of LRP/LR with siRNA inhibits several cancer hallmarks in lung cancer cells

The incidence and mortality rates of cancer are growing rapidly worldwide, with lung cancer being the most commonly occurring cancer in males. Human carcinomas circumvent the inhibitory pathways induced by DNA damage and senescence through the upregulation of telomerase activity. The 37 kDa/67 kDa laminin receptor (LRP/LR) is a cell surface receptor which plays a role in several cancer hallmarks, including metastasis, angiogenesis, cell viability maintenance, apoptotic evasion, and mediating telomerase activity. We have previously shown that the knockdown of LRP/LR with an LRP-specific siRNA significantly impedes adhesion and invasion, induces apoptosis, and inhibits telomerase activity in various cancer cell lines in vitro. Here, we investigated the effect of downregulating LRP/LR with LRP-specific siRNA in A549 lung cancer cells. Downregulation of LRP/LR resulted in a significant decrease in cell viability, migration potential, and telomerase activity, as well as a significant increase in apoptosis. Proteomic analysis further suggested the re-establishment of immune control over the lung cancer cells, a previously unidentified facet of LRP downregulation in cancer. Altogether, we suggest that targeting LRP/LR for downregulation may have therapeutic potential for inhibiting several cancer hallmarks.

LRP::FLAG Reduces Phosphorylated Tau Levels in Alzheimer's Disease Cell Culture Models

BACKGROUND

Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) plaque and neurofibrillary tangle formation, respectively. Neurofibrillary tangles form as a result of the intracellular accumulation of hyperphosphorylated tau. Telomerase activity and levels of the human reverse transcriptase (hTERT) subunit of telomerase are significantly decreased in AD. Recently, it has been demonstrated that the 37 kDa/67 kDa laminin receptor (LRP/LR) interacts with telomerase and is implicated in Aβ pathology. Since both LRP/LR and telomerase are known to play a role in the Aβ facet of AD, we hypothesized that they might also play a role in tauopathy.

OBJECTIVE

This study aimed to determine if LRP/LR has a relationship with tau and whether overexpression of LRP::FLAG has an effect on tauopathy-related proteins.

METHODS

We employed confocal microscopy and FRET to determine whether LRP/LR and tau co-localize and interact. LRP::FLAG overexpression in HEK-293 and SH-SY5Y cells as well as analysis of tauopathy-related proteins was assessed by western blotting.

RESULTS

We demonstrate that LRP/LR co-localizes with tau in the perinuclear cell compartment and confirmed a direct interaction between LRP/LR and tau in HEK-293 cells. Overexpression of LRP::FLAG in HEK-293 and SH-SY5Y cells decreased total and phosphorylated tau levels with a concomitant decrease in PrPc levels, a tauopathy-related protein. LRP::FLAG overexpression also resulted in increased hTERT levels.

CONCLUSION

This data suggest that LRP/LR extends its role in AD through a direct interaction with tau, and recommend LRP::FLAG as a possible alternative AD therapeutic via decreasing phosphorylated tau levels.

Knock-down of LRP/LR influences signalling pathways in late-stage colorectal carcinoma cells

Background

The 37 kDa/67 kDa laminin receptor (LRP/LR) is involved in several tumourigenic-promoting processes including cellular viability maintenance and apoptotic evasion. Thus, the aim of this study was to assess the molecular mechanism of LRP/LR on apoptotic pathways in late stage (DLD-1) colorectal cancer cells upon siRNA-mediated down-regulation of LRP/LR.

Methods

siRNAs were used to down-regulate the expression of LRP/LR in DLD-1 cells which was assessed using western blotting and qPCR. To evaluate the mechanistic role of LRP/LR, proteomic analysis of pathways involved in proliferation and apoptosis were investigated. The data from the study was analysed using a one-way ANOVA, followed by a two-tailed student’s t-test with a confidence interval of 95%.

Results

Here we show that knock-down of LRP/LR led to significant changes in the proteome of DLD-1 cells, exposing new roles of the protein. Moreover, analysis showed that LRP/LR may alter components of the MAPK, p53-apoptotic and autophagic signalling pathways to aid colorectal cancer cells in continuous growth and survival. Knock-down of LRP/LR also resulted in significant decreases in telomerase activity and telomerase-related proteins in the DLD-1 cells.

Conclusions

These findings show that LRP/LR is critically implicated in apoptosis and cell viability maintenance and suggest that siRNA-mediated knock-down of LRP/LR may be a possible therapeutic strategy for the treatment of colorectal cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08081-3.

Patented therapeutic approaches targeting LRP/LR for cancer treatment

Introduction: The ubiquitously expressed 37 kDa/67 kDa high-affinity laminin receptor (laminin receptor precursor/laminin receptor, LRP/LR) is a protein found to play several roles within cells. The receptor is located in the nucleus, cytosol and the cell surface. LRP/LR mediates cell proliferation, cell adhesion and cell differentiation. As a result, it is seen to enhance tumor angiogenesis as well as invasion and adhesion, key steps in the metastatic cascade of cancer. Recent findings have shown that LRP/LR is involved in the maintenance of cell viability through apoptotic evasion, allowing for tumor progression. Thus, several patented therapeutic approaches targeting the receptor for the prevention and treatment of cancer have emerged.Areas covered: The several roles that LRP/LR plays in cancer progression as well as an overview of the current therapeutic patented strategies targeting LRP/LR and cancer to date.Expert opinion: Small molecule inhibitors, monoclonal antibodies and small interfering RNAs might act used as powerful tools in preventing tumor angiogenesis and metastasis through the induction of apoptosis and telomere erosion in several cancers. This review offers an overview of the roles played by LRP/LR in cancer progression, while providing novel patented approaches targeting the receptor as potential therapeutic routes for the treatment of cancer as well as various other diseases.

Differential expression and regulation of the non-integrin 37/67-kDa laminin receptor on peripheral blood leukocytes of healthy individuals and patients with rheumatoid arthritis

The non-integrin 37/67-kDa laminin receptor (LAMR1) is a complex protein with diverse functions. LAMR1 is widely expressed in epithelial cells and recently it was reported on neutrophils and a subset of activated T cells. Ligation of LAMR1 on peripheral blood mononuclear cells (PBMC) downregulated LPS-induced TNFα production, suggesting immune functions. However, its expression on primary monocytes remain unknown. Interestingly, LAMR1 mRNA is downregulated in PBMC of patients with early rheumatoid arthritis (RA), and low gene expression is an independent predictor of poor response to anti-TNFα treatment, suggesting a role in RA pathogenesis. We found LAMR1 was constitutively expressed on all peripheral blood monocytes and a subset of B cells from healthy individuals and patients with RA and it was abundantly present in synovial tissue of patients with RA. On monocytes and synovial tissue lower levels of LAMR1 expression tended to correlate with increased disease activity scores. In vitro treatment of monocytes with IFNγ or IL-10 up-regulated surface LAMR1 in healthy individuals and patients with RA with greater effects observed in healthy individuals. Importantly, treatment with IFNγ significantly increased specific binding of monocytes to laminin-1. TNFα and IL-1β caused marginal downregulation of LAMR1 in patients but effects in controls were variable. Taken together, constitutively expressed LAMR1 on monocytes is differentially regulated by pro-inflammatory and immune-regulatory cytokines suggesting LAMR1 may regulate the threshold and amplitude of their activation and migration. Decreased levels in patients with RA may indicate loss of this potentially critical homeostatic regulation thereby contributing to the excessive inflammation.

LRP/LR specific antibody IgG1-iS18 impedes neurodegeneration in Alzheimer's disease mice

Alzheimer’s disease (AD) is a neurodegenerative disease caused by accumulation of amyloid beta (Aβ) plaque and neurofibrillary tangle formation. We have shown in vitro, that knock-down and blockade of the 37 kDa/67 kDa Laminin Receptor (LRP/LR) resulted in reduced Aβ induced cytotoxicity and Aβ accumulation. In order to test the effect of blocking LRP/LR on Aβ formation and AD associated symptoms, AD transgenic mice received the anti-LRP/LR specific antibody, IgG1-iS18 through intranasal administration. We show that this treatment resulted in an improvement in memory, and decreased Aβ plaque formation. Moreover, a significant decrease in Aβ₄₂ protein expression with a concomitant increase in amyloid precursor protein (APP) and telomerase reverse transcriptase (mTERT) levels was observed. These data recommend IgG1-iS18 as a potentially powerful therapeutic antibody for AD treatment.

Knock-down of LRP/LR promotes apoptosis in early and late stage colorectal carcinoma cells via caspase activation

Background

Cancer remains one of the leading causes of death around the world, where incidence and mortality rates are at a constant increase. Tumourigenic cells are characteristically seen to over-express the 37 kDa/67 kDa laminin receptor (LRP/LR) compared to their normal cell counterparts. This receptor has numerous roles in tumourigenesis including metastasis, angiogenic enhancement, telomerase activation, cell viability and apoptotic evasion. This study aimed to expose the role of LRP/LR on the cellular viability of early (SW-480) and late (DLD-1) stage colorectal cancer cells.

Methods

siRNA were used to down-regulate the expression of LRP/LR in SW-480 and DLD-1 cells which was assessed using western blotting. Subsequently, cell survival was evaluated using the MTT cell survival assay and confocal microscopy. Thereafter, Annexin V-FITC/PI staining and caspase activity assays were used to investigate the mechanism underlying the cell death observed upon LRP/LR knockdown. The data was analysed using Student’s t-test with a confidence interval of 95%, with p-values of less than 0.05 seen as significant.

Results

Here we reveal that siRNA-mediated knock-down of LRP led to notable decreases in cell viability through increased levels of apoptosis, apparent by compromised membrane integrity and significantly high caspase-3 activity. Down-regulated LRP resulted in a significant increase in caspase-8 and -9 activity in both cell lines.

Conclusions

These findings show that the receptor is critically implicated in apoptosis and that LRP/LR down-regulation induces apoptosis in early and late stage colorectal cancer cells through both apoptotic pathways. Thus, this study suggests that siRNA-mediated knock-down of LRP could be a possible therapeutic strategy for the treatment of early and late stage colorectal carcinoma.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4531-2) contains supplementary material, which is available to authorized users.

siRNA - Mediated LRP/LR knock-down reduces cellular viability of malignant melanoma cells through the activation of apoptotic caspases

The 37 kDa/67 kDa laminin receptor (LRP/LR) is over-expressed in tumor cells and has been implicated in several tumourigenic processes such as metastasis and telomerase activation, however, more importantly the focus of the present study is on the maintenance of cellular viability and the evasion of apoptosis. The aim of the study was to investigate the role of LRP/LR on the cellular viability of early (A375) and late stage (A375SM) malignant melanoma cells. Flow cytometry and western blot analysis revealed that A375SM cells contain more cell-surface and total LRP/LR levels in comparison to the A375 cells, respectively. In order to determine the effect of LRP/LR on cell viability and apoptosis, LRP was down-regulated via siRNA technology. MTT assays revealed that LRP knock-down led to significant reductions in the viability of A375 and A375SM cells. Confocal microscopy indicated nuclear morphological changes suggestive of apoptotic induction in both cell lines and Annexin-V FITC/PI assays confirmed this observation. Additionally, caspase-3 activity assays revealed that apoptosis was induced in both cell lines after siRNA-mediated down-regulation of LRP. Caspase-8 and -9 activity assays suggested that post LRP knock-down; A375 cells undergo apoptosis solely via the extrinsic pathway, while A375SM cells undergo apoptosis via the intrinsic pathway.

IMPLICATIONS

siRNAs mediated LRP knock-down might represent a powerful alternative therapeutic strategy for the treatment of malignant melanoma through the induction of apoptosis.

Knockdown of LRP/LR induces apoptosis in pancreatic cancer and neuroblastoma cells through activation of caspases

The 37kDa/67kDa laminin receptor (LRP/LR) serves various physiological and pathological roles such as enhancing tumour-related processes including metastasis, angiogenesis, cellular viability and telomerase activation in cancerous cell lines. The present study investigates the effect of siRNA mediated downregulation of LRP/LR on pancreatic cancer (AsPC-1) and neuroblastoma (IMR-32) cells. MTT and BrdU assays revealed that siRNA mediated downregulation of LRP resulted in a significant reduction in cell viability and cell proliferation. In addition, knock-down of LRP resulted in phosphatidylserine externalization, diminished nuclear integrity and significantly enhanced caspase-3 activity, which is indicative of apoptosis. LRP downregulation resulted in a significant increase in caspase-8 activity in IMR-32 cells and enhanced caspase-8 and 9 activity in AsPC-1 cells. These data recommend siRNA mediated knock-down of LRP as a potential therapeutic avenue for the treatment of pancreatic cancer and neuroblastoma.