37-kDa laminin receptor precursor promotes lung adenocarcinoma cell invasion and metastasis by epithelial-to-mesenchymal transition

The fusion gene LRP1-SNRNP25 drives invasion and migration by activating the pJNK/37LRP/MMP2 signaling pathway in osteosarcoma

Through transcriptome sequencing, we previously identified a new osteosarcoma-specific, frequent fusion gene, LRP1-SNRNP25, and found that it played an important role in tumor cell invasion and migration. However, the specific mechanism remains unclear. In this article, whole-genome sequencing further confirmed that the LRP1-SNRNP25 fusion gene is formed by fusion of LRP1 exon 8 and SNRNP25 exon 2. In vitro, scratch and Transwell assays demonstrated that the migration and invasion abilities of LRP1-SNRNP25-overexpressing osteosarcoma cells were significantly increased. To explore the molecular mechanism of the LRP1-SNRNP25 fusion in affecting osteosarcoma cell migration and invasion, we evaluated the migration and invasion-related molecular signaling pathways by western blotting. Some migration- and invasion-related genes, including pJNK and MMP2, were upregulated. Coimmunoprecipitation-mass spectrometry showed that 37LRP can interact with pJNK. Western blotting confirmed that LRP1-SNRNP25 overexpression upregulates 37LRP protein expression. Immunofluorescence staining showed the intracellular colocalization of LRP1-SNRNP25 with pJNK and 37LRP proteins and that LRP1-SNRNP25 expression increased the pJNK and 37LRP levels. Coimmunoprecipitation (co-IP) confirmed that LRP1-SNRNP25 interacted with pJNK and 37LRP proteins. The pJNK inhibitor SP600125 dose-dependently decreased the pJNK/37LRP/MMP2 levels. After siRNA-mediated 37LRP knockdown, the MMP2 protein level decreased. These two experiments proved the upstream/downstream relationship among pJNK, 37LRP, and MMP2, with pJNK the farthest upstream and MMP2 the farthest downstream. These results proved that the LRP1-SNRNP25 fusion gene exerts biological effects through the pJNK/37LRP/MMP2 signaling pathway. In vivo, LRP1-SNRNP25 promoted osteosarcoma cell growth. Tumor growth was significantly inhibited after SP600125 treatment. Immunohistochemical analysis showed that the pJNK, MMP2, and Ki-67 protein levels were significantly increased in tumor tissues of LRP1-SNRNP25-overexpressing cell-injected nude mice. Furthermore, lung and liver metastasis were more prevalent in these mice. In a word, LRP1-SNRNP25 promotes invasion, migration, and metastasis via pJNK/37LRP/MMP2 pathway. LRP1-SNRNP25 is a potential therapeutic target for LRP1-SNRNP25-positive osteosarcoma.

Expression and significance of laminin receptor in squamous cell carcinoma of the tongue

BACKGROUND

Laminin receptor is a non-integrin cell-surface receptor that binds laminin present on the basement membrane. It has been reported to be associated with infiltration and metastasis of various malignant tumors. However, no studies regarding tongue cancer have been reported. This study aimed to clarify the role of laminin receptor in squamous cell carcinoma of the tongue.

METHODS

We performed immunohistochemical staining of specimens from 66 patients with squamous cell carcinoma of the tongue and assessed laminin receptor expression and clinicopathological factors. As epithelial-mesenchymal transition has been shown to be associated with infiltration and metastasis of malignant tumors, staining for E-cadherin, vimentin, and N-cadherin were also performed.

RESULTS

Of 20 patients with postoperative recurrence, 14 exhibited high laminin receptor expression (p = 0.0025). Kaplan-Meier analysis revealed a significantly shorter time to postoperative recurrence for the high laminin receptor expression group than that for the low laminin receptor expression group (p = 0.0008). Based on multivariate analyses for postoperative recurrence, high laminin receptor expression was associated with poor prognosis (high expression vs. low expression; HR =3.19, 95% CI =0.92-11.08; p = 0.0682). There was a correlation between laminin receptor and N-cadherin (p = 0.0089) but not between laminin receptor and E-cadherin (p = 0.369) or vimentin (p = 0.4221).

CONCLUSION

These results suggest that high laminin receptor expression is a useful prognostic factor for postoperative recurrence and may be a target for molecular therapy to treat squamous cell carcinoma of the tongue.

A dock derived compound against laminin receptor (37 LR) exhibits anti-cancer properties in a prostate cancer cell line model

Laminin receptor (67 LR) is a 67 kDa protein derived from a 37 kDa precursor (37 LR). 37/67 LR is a strong clinical correlate for progression, aggression, and chemotherapeutic relapse of several cancers including breast, prostate, and colon. The ability of 37/67 LR to promote cancer cell aggressiveness is further increased by its ability to transduce physiochemical and mechanosensing signals in endothelial cells and modulate angiogenesis. Recently, it was demonstrated that 37/67 LR modulates the anti-angiogenic potential of the secreted glycoprotein pigment epithelium-derived factor (PEDF). Restoration of PEDF balance is a desirable therapeutic outcome, and we sought to identify a small molecule that could recapitulate known signaling properties of PEDF but without the additional complications of peptide formulation or gene delivery safety validation. We used an in silico drug discovery approach to target the interaction interface between PEDF and 37 LR. Following cell based counter screening and binding validation, we characterized a hit compound's anti-viability, activation of PEDF signaling-related genes, anti-wound healing, and anti-cancer signaling properties. This hit compound has potential for future development as a lead compound for treating tumor growth and inhibiting angiogenesis.

Human lung epithelial cells A549 epithelial-mesenchymal transition induced by PVA/Collagen nanofiber

Epithelial-mesenchymal transition (EMT) is a process by which epithelial cells lose their cell-cell contact to become mesenchymal stem cells, which is important on development and embryogenesis, wound healing, and cancer metastasis. This research aims to investigate the effect of topological cue as modulating factor on the EMT by tuning the diameter of electrospinning nanofiber. The cell-nanofiber interaction between human lung epithelial cell A549 and electrospinning nanofibers composed of polyvinyl alcohol (PVA) and type I collagen were investigated. The electrospinning of regenerated PVA/Collagen nanofibers were performed with water/acetic acid as a spinning solvent and glutaraldehyde as a chemical cross-linker. Parameterization on concentration, applied voltage and feeding rate was finalized to generate smooth nanofibers with good homogeneity. The scanning electron microscopy result demonstrated that A549 cell appropriately achieved extended morphology by the filopodia attaching to the surface of the nanofibrous mats. When the diameter changed from 90nm to 240nm, the A549 cell was correspondingly express varied EMT related genes. Gene expression analysis was conducted by qPCR using three typical markers for detecting EMT: N-cadherin (NCad), Vimentin (Vim), and Fibronectin (Fib). An increasing expression pattern was observed on cell culturing on 170nm sample with respect to cell cultured on 90nm and 240nm. This result indicated the 170nm PVA/Collagen nanofibers induce A549 cells to process epithelial-mesenchymal transition more seriously than those on 90nm or 240nm.

37LRP induces invasion in hypoxic lung adenocarcinoma cancer cells A549 through the JNK/ERK/c-Jun signaling cascade

We previously reported that 37-kDa laminin receptor precursor involved in metastasis of lung adenocarcinoma cancer cells. In this study, we further revealed that hypoxia induced 37-kDa laminin receptor precursor expression and activation of extracellular signal-regulated protein kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase in lung adenocarcinoma cancer cells. In addition, we further demonstrated that the c-Jun N-terminal kinase inhibitor SP600125 and extracellular signal-regulated protein kinase inhibitor U0126 blocked the c-Jun activity and abolished hypoxia-induced 37-kDa laminin receptor precursor expression and promoter activity in a concentration-dependent manner. However, the p38 mitogen-activated protein kinase inhibitor did not affect 37-kDa laminin receptor precursor expression and c-Jun activity in response to hypoxia. Furthermore, downregulated c-Jun expression by short interfering RNA could also inhibit hypoxia-induced 37-kDa laminin receptor precursor expression and transcriptional activity. The inhibition of 37-kDa laminin receptor precursor expression by SP600125 and U0126 could be rescued by c-Jun overexpression. Studies using luciferase promoter constructs revealed a significant increase in the activity of promoter binding in the cells exposed to hypoxia, which was lost in the cells with mutation of the activator protein 1 binding site. Electrophoresis mobility shift assay and chromatin immunoprecipitation demonstrated a functional activator protein 1 binding site within 37-kDa laminin receptor precursor gene regulatory sequence located at -271 relative to the transcriptional initiation point. Hypoxia-induced invasion of A549 cells was inhibited by the pharmacologic inhibitors of c-Jun N-terminal kinase (SP600125) and extracellular signal-regulated protein kinase (U0126) as well as 37-kDa laminin receptor precursor-specific siRNA or antibody. Our results suggest that hypoxia-elicited c-Jun/activator protein 1 regulates 37-kDa laminin receptor precursor expression, which modulates migration and invasion of lung adenocarcinoma cells.

Electrospinning of PVA/sericin nanofiber and the effect on epithelial-mesenchymal transition of A549 cells

This research aims to investigate the cell-nanomaterial interaction between epithelial-mesenchymal transition of A549 cell and electrospinning nanofibers composed of polyvinyl alcohol (PVA)/silk sericin (SS). The electrospinning of regenerated nanofiber was performed with water as a spinning solvent and glutaraldehyde as a chemical cross-linker. Solution concentration, applied voltage and spin distances as well as other parameters were optimized to generate fine nanofibers with smooth surface in good homogeneity. From the scanning electron microscopy (SEM) analysis, the nanofibers had an average diameter of 200nm. Epithelial-mesenchymal transition (EMT) is a process by which epithelial cells lose their cell polarity to become mesenchymal stem cells. This transition is affected by multiple biochemical and physical factors in cell metabolism cascade. Herein, we investigate the biophysical effect on A549 EMT by culturing cells on nanofibrous mats with different topography and composition. The cell viability was evaluated by biochemical assay and its morphology was observed with SEM. The results demonstrate that cells appropriately attached to the surface of the nanofibrous mats with extended morphology by their filopodia. Gene expression analysis was conducted by real-time PCR using multiple markers for detecting EMT: N-cadherin (NCad), Vimentin (Vim), Fibronectin (Fib) and Matrix metallopeptidase (MMP9). An increasing expression pattern was observed on NCad, Vim, Fib, with respect to a negative control as cell cultured on polystyrene dish. This result indicates the 200nm PVA/SS nanofibers may induce A549 cells to process epithelial-mesenchymal transition during the culturing.

The 37-kDa laminin receptor precursor regulates the malignancy of human glioma cells

Glioma is one of the most common brain tumors and one of the most aggressive cancers. Although extensive progress has been made regarding to the diagnosis and treatment, the mortality in glioma patients is still high. Therefore, finding new therapeutic targets to the glioma is critical to the advancement in cancer treatment. Recently, the 37-kDa laminin receptor precursor (37LRP) was reported to play important roles in occurrence of some types of cancer, indicating that this molecule may function as a key regulator in the tumor migration and metastasis. However, there is still no report to elucidate the correlation between 37LRP expression and glioma genesis and development. In this study, we found the higher expression of 37LRP in the glioma cells compared with the normal brain cells. We also indicated that the downregulation of 37LRP could affect the glioma biomarker expression and also weaken the proliferative, migratory, and metastatic capacity of glioma cells in vitro. Furthermore, 37LRP silencing inhibited the glioma tumor growth in vivo. Collectively, these data demonstrated that 37LRP regulates the metastasis of glioma cells in vitro and tumor growth in vivo, suggesting that 37LRP may function as a potential molecular target in the glioma treatment.

Long Noncoding RNA-LET Suppresses Tumor Growth and EMT in Lung Adenocarcinoma

Recently, many studies showed that long noncoding RNAs (lncRNAs) are involved in tumor progression. It is reported that lncRNA-LET is downregulated and has antitumor effect on several types of cancer. This study focuses on the role of lncRNA-LET on lung adenocarcinoma (LAC) progression. RT-PCR results indicated that frequent downregulation of lncRNA-LET in LAC tissues was related to clinicopathologic factors. lncRNA-LET knockdown significantly promoted LAC cell proliferation, invasion, and migration while lncRNA-LET overexpression obviously inhibited LAC cell proliferation, invasion, and migration, indicating a tumor inhibition of lncRNA-LET in LAC progression. Besides, lncRNA-LET inhibited EMT and negatively regulated Wnt/β-catenin pathway in part. Our study suggests that lncRNA-LET exhibits an important tumor-suppressive effect on LAC progression by inhibiting EMT and Wnt/β-catenin pathway, which provides potential therapeutic targets for LAC.

T24 HRAS transformed NIH/3T3 mouse cells (GhrasT-NIH/3T3) in serial tumorigenic in vitro/in vivo passages give rise to increasingly aggressive tumorigenic cell lines T1-A and T2-A and metastatic cell lines T3-HA and T4-PA

Cancer cells often arise progressively from "normal" to "pre-cancer" to "transformed" to "local metastasis" to "metastatic disease" to "aggressive metastatic disease". Recent whole genome sequencing (WGS) and spectral karyotyping (SKY) of cancer cells and tumorigenic models have shown this progression involves three major types of genome rearrangements: ordered small step-wise changes, more dramatic "punctuated evolution" (chromoplexy), and large catastrophic steps (chromothripsis) which all occur in random combinations to generate near infinite numbers of stochastically rearranged metastatic cancer cell genomes. This paper describes a series of mouse cell lines developed sequentially to mimic this type of progression. This starts with the new GhrasT-NIH/Swiss cell line that was produced from the NIH/3T3 cell line that had been transformed by transfection with HRAS oncogene DNA from the T24 human bladder carcinoma. These GhrasT-NIH/Swiss cells were injected s.c. into NIH/Swiss mice to produce primary tumors from which one was used to establish the T1-A cell line. T1-A cells injected i.v. into the tail vein of a NIH/Swiss mouse produced a local metastatic tumor near the base of the tail from which the T2-A cell line was established. T2-A cells injected i.v. into the tail vein of a nude NIH/Swiss mouse produced metastases in the liver and one lung from which the T3-HA (H=hepatic) and T3-PA (P=pulmonary) cell lines were developed, respectively. T3-HA cells injected i.v. into a nude mouse produced a metastasis in the lung from which the T4-PA cell line was established. PCR analysis indicated the human T24 HRAS oncogene was carried along with each in vitro/in vivo transfer step and found in the T2-A and T4-PA cell lines. Light photomicrographs indicate that all transformed cells are morphologically similar. GhrasT-NIH/Swiss cells injected s.c. produced tumors in 4% of NIH/Swiss mice in 6-10 weeks; T1-A cells injected s.c. produced tumors in 100% of NIH/Swiss mice in 7-10 days. T1-A, T-2A, T3-HA and T4-PA cells when injected i.v. into the tail produced local metastasis in non-nude or nude NIH/Swiss mice. T4-PA cells were more widely metastatic than T3-HA cells when injected i.v. into nude mice. Evaluation of the injected mice indicated a general increase in metastatic potential of each cell line in the progression as compared to the GhrasT-NIH/3T3 transformed cells. A new photomicrographic technique to follow growth rates within six preselected 2×2mm(2) grids per plate is described. Average doubling times of the transformed cells GhrasT-NIH/3T3 (17h), T1A (17.5h), T2A (15.5h), T3-HA (17.5h) and T4-PA (18.5h) (average 17.2h) were significantly faster (P=0.006) than NIH Swiss primary embryonic cells and NIH/3T3 cells (22 h each). This cell series is currently used in this lab for studies of cancer cell inhibitors, mitochondrial biogenesis and gene expression and is available for further study by other investigators for intra- and inter-laboratory comparisons of WGS, transcriptome sequencing, SKY and other analyses. The genome rearrangements in these cells together with their phenotypic properties may help provide more insights into how one tumorigenic progression occurred to produce the various cell lines that led to the highly metastatic T4-PA cell line.

Novel patented therapeutic approaches targeting the 37/67 kDa laminin receptor for treatment of cancer and Alzheimer's disease

INTRODUCTION

The 37/67 kDa high-affinity laminin receptor (laminin receptor precursor/laminin receptor, LRP/LR) is a multi-faceted cellular receptor. It plays a vital role in the malignancy of various cancer types where it is seen to contribute to invasion, adhesion, apoptosis evasion and angiogenesis. Furthermore, it has been found to play an important role in facilitating the processes leading to neurotoxicity in Alzheimer's disease (AD). Various therapeutic options targeting this receptor have been patented with the outlook on application for the treatment/prevention of these diseases.

AREAS COVERED

The various roles that LRP/LR plays in cancer, AD and infectious diseases caused by viruses and bacteria have been examined in detail and an overview of the current patented therapeutic strategies targeting this receptor is given.

EXPERT OPINION

Molecular tools directed against LRP/LR, such as antibodies and small interfering RNA, could prove to be effective in the prevention of metastasis and angiogenesis while inducing apoptosis in cancers. Moreover, these strategies could also be applied to AD where LRP/LR is seen to facilitate the production and internalization of the neurotoxic Aβ peptide. This review provides a comprehensive overview of the mechanisms by which LRP/LR is involved in eliciting pathogenic events, while showing how the use of patented approaches targeting this receptor could be used to treat them.

Krüppel-like factor 8 involved in hypoxia promotes the invasion and metastasis of gastric cancer via epithelial to mesenchymal transition

Previously, we reported that hypoxia was able to induce invasion and metastasis in gastric cancer and that hypoxia-inducible factor-1 (HIF-1) is a key factor involved in this tumor type. Krüppel-like factor 8 (KLF8) as a transcriptional repressor has been suggested as a promoter of tumor metastasis in breast cancer and an inducer of the epithelial‑mesenchymal transition (EMT). KLF8 is also highly expressed in gastric cancer tissues, contributing to poor prognosis. However, the association between KLF8 and HIF-1 in regulating the progression of human gastric cancer in hypoxia is unclear. In the present study, we found that KLF8 was overexpressed in gastric cancer metastatic tissues and cells. Additionally, KLF8 siRNA significantly inhibited SGC7901 cell invasion and migration compared with SGC7901, SGC7901/Scr-si cells. Hypoxia is thus able to induce KLF8 expression and EMT in SGC7901 cells. However, following the examination of changes in cell morphology and epithelial and mesenchymal markers, it was found that KLF8 siRNA and HIF-1 siRNA strongly reversed EMT in cells undergoing hypoxia. Furthermore, hypoxia-induced KLF8 overexpression was attenuated by HIF-1 siRNA. Experiments using luciferase promoter constructs resulted in a marked increase in the activity of cells exposed to hypoxia and decreased activity in cells co-transfected with HIF-1 siRNA. The chromatin immunoprecipitation assay revealed proximal HRE at -133 is the main HIF-1 binding site in the KLF8 promoter. In conclusion, the results demonstrated that KLF8 is actively enhanced by hypoxia and is a novel HIF-1 target. KLF8 is a novel EMT regulating transcription factor that involved in the progression of gastric cancer. The specific anti-EMT drugs in combination with anti-hypoxia are new promising cancer therapies.