Amino-terminal fragments of laminin γ2 chain retract vascular endothelial cells and increase vascular permeability

Release of miR-29 Target Laminin C2 Improves Skin Repair

miRNAs are small noncoding RNAs that regulate mRNA targets in a cell-specific manner. miR-29 is expressed in murine and human skin, where it may regulate functions in skin repair. Cutaneous wound healing model in miR-29a/b1 gene knockout mice was used to identify miR-29 targets in the wound matrix, where angiogenesis and maturation of provisional granulation tissue was enhanced in response to genetic deletion of miR-29. Consistently, antisense-mediated inhibition of miR-29 promoted angiogenesis in vitro by autocrine and paracrine mechanisms. These processes are likely mediated by miR-29 target mRNAs released upon removal of miR-29 to improve cell-matrix adhesion. One of these, laminin (Lam)-c2 (also known as laminin γ2), was strongly up-regulated during skin repair in the wound matrix of knockout mice. Unexpectedly, Lamc2 was deposited in the basal membrane of endothelial cells in blood vessels forming in the granulation tissue of knockout mice. New blood vessels showed punctate interactions between Lamc2 and integrin α6 (Itga6) along the length of the proto-vessels, suggesting that greater levels of Lamc2 may contribute to the adhesion of endothelial cells, thus assisting angiogenesis within the wound. These findings may be of translational relevance, as LAMC2 was deposited at the leading edge in human wounds, where it formed a basal membrane for endothelial cells and assisted neovascularization. These results suggest a link between LAMC2, improved angiogenesis, and re-epithelialization.

Expression of laminin332 γ2 at the invasive front is associated with tumor budding and poor prognosis in cutaneous squamous cell carcinoma

Laminin332 is a glycoprotein consisting of α3/β3/γ2 chains, of which the γ2 chain (Ln-γ2) is expressed in tumor cells at the invasive front in many types of malignant tumors. We have previously reported that Ln-γ2 is associated with tumor invasion of cutaneous squamous cell carcinoma (cSCC) in vivo and in vitro. Recently, tumor budding (TB; invasion patterns in small clusters of less than five cancer cells in the stroma at the invasive front) has been reported to be a risk factor for lymph node metastasis in cSCC. Based on these findings, we speculated that expression of Ln-γ2 is related to TB in cSCC and would be an invasive factor that causes lymph node metastasis. In this study, we investigated the relationship between Ln-γ2 expression and clinicopathological findings, including TB, in 102 cases of cSCC using immunohistochemistry. The results showed that high expression of Ln-γ2 at the invasive front correlated with a high TB score. In addition, high Ln-γ2 expression at the invasive front was also associated with lymphatic invasion, lymph node metastasis, and poor prognosis (death or recurrence), as in TB. Furthermore, we showed a positive association between Ln-γ2 expression at the invasive front and Yes-associated protein (YAP) expression in the Hippo pathway. Our results suggest that Ln-γ2 expression at the invasive front may have a role in TB formation via YAP and contribute to prognosis by causing lymphatic invasion and lymph node metastasis. The expression of Ln-γ2 would be useful for risk assessment of lymph node metastasis and poor prognosis in routine practice of cSCC.

Comparative study of laminin332-γ2 chain expression in oral lichen planus and squamous cell carcinoma by immunohistochemistry

BACKGROUND

Classification of oral lichen planus (OLP) as a condition with malignant potential is still controversial. One of the major properties of malignancy is invasion. Ln332-γ2 chain plays a critical role in invasive activity of cancer cells. This study aims to compare Ln332-γ2 chain expression in OLP, oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC).

METHODS

Ln332-γ2 expression was evaluated in 16 epithelial hyperplasia with no dysplasia (group A), 16 OLP (group B), 18 OED (group C) and 18 OSCC (group D) by immunohistochemistry.

RESULTS

Except in A group, Ln332-γ2 expression was detected in other groups. There was a significant difference in Ln332-γ2 expression among B, C and D groups as well as between B and D, C and D groups (P< 0.001). However, there was no significant difference between B and C groups (P= 0.999).

CONCLUSIONS

According to the findings of this study, the likelihood of similarity of OLP with premalignant dysplastic lesion can be suggested. This is not corroborating OLP definitive transformation to an OSCC. But it might be advisable that OLPs with >10% Ln332- γ2 expression may have a higher risk of cellular invasion occurrence and malignant transformation.

Sortilin regulates blood-brain barrier integrity

Brain homeostasis depends on the existence of the blood-brain barrier (BBB). Despite decades of research, the factors and signalling pathways for modulating and maintaining BBB integrity are not fully elucidated. Here, we characterise the expression and function of the multifunctional receptor, sortilin, in the cells of the BBB, in vivo and in vitro. We show that sortilin acts as an important regulatory protein of the BBB's tightness. In rats lacking sortilin, the BBB was leaky, which correlated well with relocated distribution of the localisation of zonula occludens-1, VE-cadherin and β-catenin junctional proteins. Furthermore, the absence of sortilin in brain endothelial cells resulted in decreased phosphorylation of Akt signalling protein and increased the level of phospho-ERK1/2. As a putative result of MAPK/ERK pathway activity, the junctions between the brain endothelial cells were disintegrated and the integrity of the BBB became compromised. The identified barrier differences between wild-type and Sort1-/- brain endothelial cells can pave the way for a better understanding of sortilin's role in the healthy and diseased BBB.

Regulation of vascular permeability in cancer metastasis

Enhancement of vascular permeability is indispensable for cancer metastasis. Weakened endothelial barrier function enhances vascular permeability. Circulating tumor cells moving in the microvasculature tend to invade into stromal tissue at the location where vascular permeability is enhanced. Many basic studies have identified permeability factors by using gene‐modified animals and cells. These factors directly/indirectly interact with endothelial cells. Here, we review vascular permeability factors and their molecular mechanisms. Interactions between tumor cells and endothelial cells are also discussed in the process of extravasation, one of the most critical steps in tumor metastasis. In some cases, primary tumors can manipulate permeability in a remote organ by secreting permeability factors. In addition, the importance of glycocalyx, which covers the endothelial cell surface, in controlling vascular permeability and tumor metastasis is also described. Furthermore, analysis of the hyperpermeable region found in a mouse model study is introduced. It clearly showed that tumor‐bearing mouse lungs had a hyperpermeable region due to the influence of a remote primary tumor, and fibrinogen deposition was observed in that region. Given that fibrinogen was reported to be a permeability factor and a key regulator of inflammation, eliminating fibrinogen deposition may prevent future metastasis.

Gene Expression Profile of Isolated Dermal Vascular Endothelial Cells in Keloids

Wound healing is a complex biological process, and imbalances of various substances in the wound environment may prolong healing and lead to excessive scarring. Keloid is abnormal proliferation of scar tissue beyond the original wound margins with excessive deposition of extracellular matrix (ECM) and chronic inflammation. Despite numerous previous research efforts, the pathogenesis of keloid remains unknown. Vascular endothelial cells (VECs) are a major type of inductive cell in inflammation and fibrosis. Despite several studies on vascular morphology in keloid formation, there has been no functional analysis of the role of VECs. In the present study, we isolated living VECs from keloid tissues and investigated gene expression patterns using microarray analysis. We obtained 5 keloid tissue samples and 6 normal skin samples from patients without keloid. Immediately after excision, tissue samples were gently minced and living cells were isolated. Magnetic-activated cell sorting of VECs was performed by negative selection of fibroblasts and CD45⁺ cells and by positive selection of CD31⁺cells. After RNA extraction, gene expression analysis was performed to compare VECs isolated from keloid tissue (KVECs) with VECs from normal skin (NVECs). After cell isolation, the percentage of CD31⁺ cells as measured by flow cytometry ranged from 81.8%–98.6%. Principal component analysis was used to identify distinct molecular phenotypes in KVECs versus NVECs and these were divided into two subgroups. In total, 15 genes were upregulated, and 3 genes were downregulated in KVECs compared with NVECs using the t-test (< 0.05). Quantitative RT-PCR and immunohistochemistry showed 16-fold and 11-fold overexpression of SERPINA3 and LAMC2, respectively. SERPINA3 encodes the serine protease inhibitor, α1-antichymotripsin. Laminin γ2-Chain (LAMC2) is a subunit of laminin-5 that induces retraction of vascular endothelial cells and enhances vascular permeability. This is the first report of VEC isolation and gene expression analysis in keloid tissue. Our data suggest that SERPINA3 and LAMC2 upregulation in KVECs may contribute to the development of fibrosis and prolonged inflammation in keloid. Further functional investigation of these genes will help clarify the mechanisms of abnormal scar tissue proliferation.

Expression of Laminin γ2 Proteolytic Fragments in Murine Skin Following Exposure to Sulfur Mustard

Laminin-332 is a basement membrane protein composed of three genetically distinct polypeptide chains that actively promote both skin epidermal cell adhesion and migration. Proteolytic fragments of the laminin γ2 chain stimulate migration and scattering of keratinocytes and cancer cells. Sulfur mustard (SM) is a bifunctional alkylating agent that induces separation of basal keratinocytes from the dermal-epidermal junction and invokes a strong inflammatory response leading to delayed wound repair. In the present studies, the role of laminin γ2 in SM-induced skin injury and wound repair was investigated using the mouse ear vesicant model. We found that laminin γ2 chain mRNA was preferentially upregulated in mouse ear skin exposed to SM. In situ hybridization confirmed overexpression of laminin γ2 transcript. Western blot analysis showed increased protein expression of the full-length proform of laminin γ2 and smaller processed fragments of laminin γ2 in skin exposed to SM. Dual immunofluorescence labeling indicated that laminin γ2 fragments are prevalent in suprabasal keratinocytes behind the leading edge in areas of hyperplasia in injured skin. In addition, co-expression of laminin γ2 and the senescent marker, p16^-INK4a was found to overlap with the hyperplastic migratory epithelial sheet. This observation is similar to hypermotile keratinocytes reported in invasive carcinoma cells. Overall, our studies indicate that laminin γ2 is preferentially expressed in skin post SM exposure and that protein expression appears to become progressively more fragmented. The laminin γ2 fragments may play a role in regulating SM-induced skin wound repair. Anat Rec, 2020. © 2020 American Association for Anatomy.

F5-Peptide and mTORC1/rpS6 Effectively Enhance BTB Transport Function in the Testis-Lesson From the Adjudin Model

During spermatogenesis, the blood-testis barrier (BTB) undergoes cyclic remodeling that is crucial to support the transport of preleptotene spermatocytes across the immunological barrier at stage VIII to IX of the epithelial cycle. Studies have shown that this timely remodeling of the BTB is supported by several endogenously produced barrier modifiers across the seminiferous epithelium, which include the F5-peptide and the ribosomal protein S6 [rpS6; a downstream signaling molecule of the mammalian target of rapamycin complex 1 (mTORC1)] signaling protein. Herein, F5-peptide and a quadruple phosphomimetic (and constitutively active) mutant of rpS6 [i.e., phosphorylated (p-)rpS6-MT] that are capable of inducing reversible immunological barrier remodeling, by making the barrier "leaky" transiently, were used for their overexpression in the testis to induce BTB opening. We sought to examine whether this facilitated the crossing of the nonhormonal male contraceptive adjudin at the BTB when administered by oral gavage, thereby effectively improving its BTB transport to induce germ cell adhesion and aspermatogenesis. Indeed, it was shown that combined overexpression of F5-peptide and p-rpS6-MT and a low dose of adjudin, which by itself had no noticeable effects on spermatogenesis, was capable of perturbing the organization of actin- and microtubule (MT)-based cytoskeletons through changes in the spatial expression of actin- and MT-binding/regulatory proteins to the corresponding cytoskeleton. These findings thus illustrate the possibility of delivering drugs to any target organ behind a blood-tissue barrier by modifying the tight junction permeability barrier using endogenously produced barrier modifiers based on findings from this adjudin animal model.

Highly sensitive detection of invasive lung cancer cells by novel antibody against amino-terminal domain of laminin γ2 chain

The laminin γ2 chain, a subunit of laminin-332 (α3β3γ2), is a molecular marker for invasive cancer cells, but its pathological roles in tumor progression remain to be clarified. It was recently found that the most N-terminal, domain V (dV) of γ2 chain has activities to bind CD44 and stimulate tumor cell migration and vascular permeability. In the present study, we prepared a mAb recognizing γ2 dV. Immunoblotting with this antibody, for the first time, showed that proteolytic fragments containing dV in a range of 15-80 kDa were highly produced in various human cancer cell lines and lung cancer tissues. In immunohistochemistry of adenocarcinomas and squamous cell carcinomas of the lung, this antibody immunostained the cytoplasm of invasive tumor cells and adjacent stroma much more strongly than a widely used antibody recognizing the C-terminal core part of the processed γ2 chain. This suggests that the dV fragments are highly accumulated in tumor cells and stroma compared to the processed γ2 protein. The strong tumor cell staining with the dV antibody correlated with the tumor malignancy grade. We also found that the laminin β3 and α3 chains were frequently overexpressed in tumor cells and tumor stroma, respectively. The cytoplasmic dV detection was especially prominent in tumor cells infiltrating stroma, but low in the cells surrounded by basement membranes, suggesting that the active tumor-stroma interaction is critical for the aberrant γ2 expression. The present study suggests important roles of laminin γ2 N-terminal fragments in tumor progression.

Expression of Lamininγ2 in extrahepatic cholangiocarcinoma tissues and its influence on tumor invasion and metastasis

OBJECTIVE

To explore the expression of lamininγ2 in extrahepatic cholangiocarcinoma (EHCC) tissues and its influence on tumor invasion and metastasis.

MATERIALS AND METHODS

Paraffin embedding samples of cancer, para-cancer, lymph node metastatic and hepatic metastatic tissues from 79 patients undergoing EHCC resection were collected. Expression of lamininγ2 was detected by immunohistochemistry and its relationship with clinical pathological characteristics and the prognosis of EHCC patients were analyzed.

RESULTS

Lamininγ2 showed negative staining in para-cancer tissues, but demonstrated a 51.9% (41/79) positive expression rate in extracellular matrix (ECM) or cytoplasm of EHCC tissues. In lymph node metastatic and distant metastatic nidi, expression of lamininγ2 was significantly higher than in the primary nidi (χ2=7.4173, P=0.0065; χ2=4.0077, P=0.0453). The expression was in obvious association with lymph node metastasis (P<0.01), but had no relevance with age, gender, tumor location, tumor stage, differentiation and distant metastasis in ECM (P>0.05), whereas it was in marked connection with lymph node and distant metastasis (P<0.05 or P<0.01), but had no relationship with age, gender, tumor location, tumor stage and differentiation in cytoplasm (P>0.05). However, the median survival time and median recurrent period of patients with positive expression of lamininγ2 in both cytoplasm and ECM of tumor cells, only in ECM and only in cytoplasm, were evidently lower than with negative expression of lamininγ2 in RCM and cytoplasm (P<0.05 or P<0.01). Further Cox regression analysis showed that the positive expression of lamininγ2 and the tumor differentiation were independent risk factors influencing the prognosis of EHCC patients.

CONCLUSIONS

Abnormal expression of lamininγ2 may be closely associated with invasion and metastasis of tumor cells, and thus a potential molecular marker for prognosis of EHCC patients.

Amino-terminal fragments of laminin γ2 chain stimulate migration of metastatic breast cancer cells by interacting with CD44

Laminin γ2 (Lmγ2) chain, a subunit of the basement membrane protein laminin-332, is regarded as a typical cancer invasion marker. The overexpression of Lmγ2 chain by invasive cancer cells correlates with poor prognosis of cancer patients, and its forced expression in human cancer cells promotes their invasive growth in a nude mouse model. However, its actual roles in cancer progression, as well as the mechanism of its proinvasive effect, remain unclear. CD44 is known to be an important cancer stem cell marker and support cancer progression and stem cell functions. Here we demonstrate that amino-terminal fragments of Lmγ2 interact with CD44 on the membrane of breast cancer cells. Lmγ2 highly bound to the metastatic cell line MDA-MB-231 but poorly to the benign cell line MCF-7. The membrane receptor for Lmγ2 on MDA-MB-231 cells was identified to be the standard form of CD44 (CD44s) by co-immunoprecipitation, affinity chromatography and direct protein interaction assay. Lmγ2 interacted with CD44s through EGF-like repeat 2/3 in the Lmγ2 amino-terminus. Amino-terminal fragments of Lmγ2 induced the phosphorylation of CD44 cytoplasmic domain and stimulated migration of the cancer cells in a CD44-dependent manner. This migration was blocked by inhibitors of TGF-β receptor I (TGF-βRI) kinase. These results suggest that two important tumor markers, Lmγ2 and CD44, cooperate for cancer progression and possibly for cancer stem cell functions. TGF-βRI may be involved in the Lmγ2/CD44 interaction.