Development of a new tracking tool for the human monomeric laminin-gamma 2 chain in vitro and in vivo

Hepatocyte transformation is induced by laminin γ2 monomer

Serum laminin-γ2 monomer (Lm-γ2m) is a potent predictive biomarker for hepatocellular carcinoma (HCC) onset in patients with hepatitis C infection who achieve a sustained virologic response with liver cirrhosis (LC) and for the onset of extrahepatic metastases in early-stage HCC. Although Lm-γ2m involvement in late-stage cancer progression has been well investigated, its precise roles in HCC onset remain to be systematically investigated. Therefore, we analyzed an HCC model, human hepatocytes and cholangiocytes, and surgically resected liver tissues from patients with HCC to understand the roles of Lm-γ2m in HCC onset. Ck-19- and EpCAM-positive hepatic progenitor cells (HPCs) in the liver of pdgf-c transgenic HCC mouse model with ductular reaction showed ectopic expression of Lm-γ2m. Forced expression of Lm-γ2m in hepatocytes adjacent to HPCs resulted in enhanced tumorigenicity, cell proliferation, and migration in immortalized hepatocytes, but not in cholangiocytes in vitro. Further, pharmacological inhibition of epidermal growth factor receptor (EGFR) and c-Jun activator JNK suppressed Lm-γ2m-induced hepatocyte transformation, suggesting the involvement of EGFR/c-Jun signaling in the transformation, leading to HCC development. Finally, immunohistochemical staining of HCC tissues revealed a high level of Lm-γ2 expression in the HPCs of the liver with ductular reaction in normal liver adjacent to HCC tissues. Overall, HPC-derived Lm-γ2m in normal liver with ductular reaction acts as a paracrine growth factor on surrounding hepatocytes and promotes their cellular transformation through the EGFR/c-Jun signaling pathway. Furthermore, this is the first report on Lm-γ2m expression detected in the normal liver with ductular reaction, a human precancerous lesion of HCC.

Biomarkers Identification in the Microenvironment of Oral Squamous Cell Carcinoma: A Systematic Review of Proteomic Studies

An important determinant for oral squamous cell carcinoma (OSCC) onset and outcome is the composition of the tumor microenvironment (TME). Thus, the study of the interactions occurring among cancer cells, immune cells, and cancer-associated fibroblasts within the TME could facilitate the understanding of the mechanisms underlying OSCC development and progression, as well as of its sensitivity or resistance to the therapy. In this context, it must be highlighted that the characterization of TME proteins is enabled by proteomic methodologies, particularly mass spectrometry (MS). Aiming to identify TME protein markers employable for diagnosing and prognosticating OSCC, we have retrieved a total of 119 articles spanning 2001 to 2023, of which 17 have passed the selection process, satisfying all its criteria. We have found a total of 570 proteins detected by MS-based proteomics in the TME of OSCC; among them, 542 are identified by a single study, while 28 are cited by two or more studies. These 28 proteins participate in extracellular matrix remodeling and/or energy metabolism. Here, we propose them as markers that could be used to characterize the TME of OSCC for diagnostic/prognostic purposes. Noteworthy, most of the 28 individuated proteins share one feature: being modulated by the hypoxia that is present in the proliferating OSCC mass.

Clinical evaluation of urine laminin-γ2 monomer as a potent biomarker for non-muscle invasive bladder cancer

BACKGROUND

To evaluate whether urine laminin-γ2 monomer (Ln-γ2m) offers a useful biomarker for patients with non-muscle-invasive bladder cancer (NMIBC).

METHODS

Participants comprised 297 patients, including 111 patients with NMIBC, 136 patients with benign genitourinary disease (BD) and 50 healthy donors (HD). Urine Ln-γ2m was prospectively measured and accuracy was analyzed. Receiver operating characteristic (ROC) curves were determined and area under the ROC curve (AUC) was calculated for urine Ln-γ2m, and compared to those of traditional urine tumor markers such as nuclear matrix protein 22 (NMP22), bladder tumor antigen (BTA) and cytology. The net benefits of combining urine markers were analyzed by decision curve analysis.

RESULTS

Mean urine Ln-γ2m was significantly higher in NMIBC than in BD or HD. The AUC for urine Ln-γ2m was significantly higher than those for urine NMP22, BTA or cytology when comparing NMIBC with HD. In patients with low-grade NMIBC, the AUC for urine Ln-γ2m was higher than the AUCs for NMP22, BTA or cytology. A net benefit of combined examination using urine Ln-γ2m/uCRN with NMP22 was demonstrated.

CONCLUSION

These results suggest urine Ln-γ2m as a potentially useful biomarker for NMIBC, particularly in cases of low-grade cancer.

Novel LAMC2 fusion protein has tumor-promoting properties in ovarian carcinoma

Laminins are heterotrimeric ECM proteins composed of α, β, and γ chains. The γ2 chain (Lm-γ2) is a frequently expressed monomer and its expression is closely associated with cancer progression. Laminin-γ2 contains an epidermal growth factor (EGF)-like domain in its domain III (DIII or LEb). Matrix metalloproteinases can cleave off the DIII region of Lm-γ2 that retains the ligand activity for EGF receptor (EGFR). Herein, we show that a novel short form of Lm-γ2 (Lm-γ2F) containing DIII is generated without requiring MMPs and chromosomal translocation between LAMC2 on chromosome 1 and NR6A1 gene locus on chromosome 9 in human ovarian cancer SKOV3 cells. Laminin-γ2F is expressed as a truncated form lacking domains I and II, which are essential for its association with Lm-α3 and -β3 chains of Lm-332. Secreted Lm-γ2F can act as an EGFR ligand activating the EGFR/AKT pathways more effectively than does the Lm-γ2 chain, which in turn promotes proliferation, survival, and motility of ovarian cancer cells. LAMC2-NR6A1 translocation was detected using in situ hybridization, and fusion transcripts were expressed in ovarian cancer cell tissues. Overexpression and suppression of fusion transcripts significantly increased and decreased the tumorigenic growth of cells in mouse models, respectively. To the best of our knowledge, this is the first report regarding a fusion gene of ECM showing that translocation of LAMC2 plays a crucial role in the malignant growth and progression of ovarian cancer cells and that the consequent product is a promising therapeutic target against ovarian cancers.

Serum Laminin γ2 Monomer as a Diagnostic and Predictive Biomarker for Hepatocellular Carcinoma

BACKGROUNDS AND AIMS

Structural dynamics of basement membrane components are still to be elucidated in the process of hepatocarcinogenesis. We evaluated the characteristics of HCC expressing laminin γ2 monomer (LG2m), a basement membrane component not detected in normal tissues, for HCC diagnosis. We further determined whether elevated serum LG2m is a risk factor for HCC development in patients with chronic hepatitis C (CHC).

APPROACH AND RESULTS

In HCC cell lines, LG2m was expressed in alpha-fetoprotein (AFP)-negative, CD90-positive cells characterized by highly metastatic natures. Using 14 cell lines and 258 HCC microarray data, we identified that LG2m gene signature was associated with Hoshida's S1/Boyault's G3 molecular subclasses with poor prognosis, which could not be recognized by AFP. Serum LG2m was assessed in 24 healthy donors, 133 chronic liver disease patients, and 142 HCC patients, and sensitivity and specificity of LG2m testing for HCC diagnosis were 62.9% and 70.5%, respectively (cutoff, 30 pg/mL). We evaluated the consequence of LG2m elevation in two independent HCC cohorts (n = 47 and n = 81), and LG2m-high HCC showed poor prognosis with later development of distant organ metastasis (cutoff, 60 pg/mL). LG2m was slightly elevated in a subset of CHC patients, and Kaplan-Meier analysis indicated a high incidence of HCC (n = 70). For validation, we enrolled 399 CHC patients with sustained virological response (SVR) as a multicenter, prospective study, and serum LG2m elevation correlated with a high incidence of HCC in the CHC patients with SVR (P < 0.0001).

CONCLUSIONS

LG2m is a predictive biomarker for the development of metastatic HCC. Elevated serum LG2m is an HCC risk in CHC patients who have achieved SVR.

hsa‑miR‑5580‑3p inhibits oral cancer cell viability, proliferation and migration by suppressing LAMC2

The present study aimed to explore whether and how microRNA-5580-3p (miR-5580-3p) affected oral cancer (OC) cell phenotypes via regulation of laminin subunit γ2 (LAMC2). Bioinformatics analysis was used to identify miR-5580-3p/LAMC2, a novel interactome that, to the best of our knowledge, has not been studied previously in OC. In the present study, the expression levels of miR-5580-3p and LAMC2 were detected by reverse transcription-quantitative PCR, while the protein expression levels of LAMC2 were identified using western blotting. To determine the effects of miR-5580-3p and LAMC2 in OC, a number of experiments, including Cell Counting Kit-8, 5-bromo-2′-deoxyuridine cell proliferation and wound healing migration assays, were performed using OC SCC-4 and Cal-27 cell lines. Additionally, luciferase reporter assays were employed to examine the interaction between miR-5580-3p and LAMC2 mRNA. The results demonstrated that miR-5580-3p expression was downregulated, while LAMC2 expression was upregulated in OC tissues and cell lines. In addition to the observation that miR-5580-3p promoted the malignant phenotypes of OC, it was also revealed that miR-5580-3p inhibited OC cell viability, proliferation and migration by suppressing LAMC2. Therefore, the present study suggested that miR-5580-3p and LAMC2 may be potential biomarkers and therapeutic targets for OC diagnosis and therapies in the future.

Laminin 332 in cancer: When the extracellular matrix turns signals from cell anchorage to cell movement

Laminin 332 is crucial in the biology of epithelia. This large extracellular matrix protein consists of the heterotrimeric assembly of three subunits - α3, β3, and γ2 - and its multifunctionality relies on a number of extracellular proteolytic processing events. Laminin 332 is central to normal epithelium homeostasis by sustaining cell adhesion, polarity, proliferation, and differentiation. It also supports a major function in epithelial tissue formation, repair, and regeneration by buttressing cell migration and survival and basement membrane assembly. Interest in this protein increased after the discovery that its expression is perturbed in tumor cells, cancer-associated fibroblasts, and the tumor microenvironment. This review summarizes current knowledge regarding the established involvement of the laminin 332 γ2 chain in tumor invasiveness and discusses the role of its α3 and β3 subunits.

Unique Biological Activity and Potential Role of Monomeric Laminin-γ2 as a Novel Biomarker for Hepatocellular Carcinoma: A Review

Laminin (Ln)-332 consists of α3, β3, and γ2 chains, which mediate epithelial cell adhesion to the basement membrane. Ln-γ2, a component of Ln-332, is frequently expressed as a monomer in the invasion front of several types of malignant tissues without simultaneous expression of Ln-α3 and/or Ln-β3 chains. Moreover, monomeric Ln-γ2 induces tumor cell proliferation and migration in vitro. These unique biological activities indicate that monomeric Ln-γ2 could be a candidate biomarker for early cancer surveillance. However, the present immune method for monomeric Ln-γ2 detection can only predict its expression, since no antibody that specifically reacts with monomeric γ2, but not with heterotrimeric γ2 chain, is commercially available. We have, therefore, developed monoclonal antibodies to specifically detect monomeric Ln-γ2, and devised a highly sensitive method to measure serum monomeric Ln-γ2 levels using a fully automated chemiluminescent immunoassay (CLIA). We evaluated its diagnostic value in sera from patients with several digestive cancers, including hepatocellular carcinoma (HCC), and found serum monomeric Ln-γ2 to be a clinically available biomarker for HCC surveillance. The combination of monomeric Ln-γ2 and prothrombin induced by Vitamin K Absence II (PIVKA-II) may be more sensitive for clinical diagnosis of HCC than any currently used combination.

Development of a fully automated chemiluminescence immunoassay for urine monomeric laminin-γ2 as a promising diagnostic tool of non-muscle invasive bladder cancer

BACKGROUND

Monomeric laminin-γ2 in urine is a potential biomarker for bladder cancer. However, the current detection system uses an antibody that cannot discriminate between monomeric laminin-γ2 and the heterotrimeric γ2 chain of laminin-332, which may cause false-positive reactions. The present study aimed to develop a fully automated chemiluminescence immunoassay system using a specific monoclonal antibody against monomeric laminin-γ2.

METHODS

In total, 237 urine specimens (84 from patients with bladder cancer, 48 from patients with benign urological disease, and 105 from healthy donors) were collected, and monomeric laminin-γ2 values in the urine were measured using a fully automated chemiluminescence immunoassay.

RESULTS

The results revealed that laminin-γ2 values in patients with benign urological disease were comparable to those of healthy donors and that the chemiluminescence immunoassay's lower limit of detection was 10 pg/mL (approximately 20-fold better than the sandwich enzyme-linked immunosorbent assay's limit of 200 pg/mL). Moreover, the chemiluminescence immunoassay demonstrated that patients with bladder cancer, including non-muscle invasive bladder cancer (≤pT1), had higher laminin-γ2 values than patients with benign urological disease or healthy donors.

CONCLUSIONS

These results suggest that urine monomeric laminin-γ2 may be a promising biomarker to diagnose cases of non-muscle invasive bladder cancer using a fully automated chemiluminescence immunoassay system.

Serum monomeric laminin-γ2 as a novel biomarker for hepatocellular carcinoma

The diagnosis of hepatocellular carcinoma (HCC) in the early stages is important for successful clinical management. Laminin (Ln)-γ2 expression has been reported in various types of malignant carcinomas. We recently developed a highly sensitive method to measure serum monomeric Ln-γ2 levels using a fully automated chemiluminescent immunoassay (CLIA). Using our CLIA, we evaluated its diagnostic value in sera from patients with chronic liver disease (CLD) and patients with hepatocellular carcinoma (HCC). Serum alpha-fetoprotein (AFP) and des-gamma-carboxy prothrombin (DCP) were also examined in these subjects. Median levels of Ln-γ2 were significantly higher in patients with HCC (173.2 pg/mL; range: 39.5-986 pg/mL) compared with patients with CLD (76.7 pg/mL; range: 38.7-215.9 pg/mL) and with healthy volunteers (41.1 pg/mL; range: 10.9-79.0 pg/mL). The optimal cutoff value for Ln-γ2 that allowed us to distinguish between HCC and nonmalignant CLD was 116.6 pg/mL. Elevated Ln-γ2 levels were observed in 0% of healthy volunteers, 17% of patients with CLD, and 63% of patients with HCC. The positivity rate in patients with HCC for the combination of Ln-γ2 and DCP was 89.5%, which was better than that for either of the two markers alone (63% and 68%, respectively). Among patients with early-stage HCC (T1 or T2), the positivity rates for monomeric Ln-γ2, AFP and DCP were 61%, 39% and 57%, respectively. Serum Ln-γ2 may be a potential biomarker for HCC surveillance. The combination of Ln-γ2 and DCP may be more sensitive for laboratory diagnosis of HCC than the combination of AFP and DCP.

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.

Static magnetic field controls cell cycle in cultured human glioblastoma cells

Magnetic field has been widely used in clinical diagnostics or for clinical treatment and is an important biomedical technology. Glioblastoma multiforme U87 and U251 are models of a fast growing malignant cancer. We focused on cellular level drafting of these cell lines as a time-dependent effect indicator of static magnetic fields (2000 ± 600 Gauss) by using their fast-growing properties. Cell viability showed a significant decrease (p < 0.01). The results coincided with the occurrence of apoptotic signals or protein expression of cyclin B1 and cyclin dependent kinase 1 in a non-apoptotic manner. Cdk1 was decreased in proportion to ankyrin G and cyclin B1 (Chi-square test, p = 0.0366). Our findings suggest that static magnetic stimulation creates a specific cyto-proliferative pattern, rather than producing randomized growth impairment.

Tumor budding and laminin5-γ2 in squamous cell carcinoma of the external auditory canal are associated with shorter survival

Squamous cell carcinoma (SCC) of the external auditory canal (EAC) is rare, usually presents at an advanced stage, and is a more aggressive tumor with poor prognosis. The University of Pittsburgh TNM staging system commonly used in prognostication is not perfect, and more accurate biomarkers predicting prognosis are needed. Tumor budding is an established negative prognostic factor at the invasive front in colorectal cancer. Moreover, immunohistochemical studies showed that laminin 5-γ2 (Ln5-γ2) is expressed at the invasive front in tumor or tumor budding cells. We assessed the prognostic significance of tumor budding and Ln5-γ2 expression by performing Ln5-γ2 immunohistochemistry and evaluated the degree of tumor budding in pre-treatment biopsy specimens, and investigated their correlations to clinicopathological parameters in patients with SCC of the EAC. Patients whose tumors had high budding grade and Ln5-γ2 expression had significantly shorter survival times. Budding grade was significantly correlated with Ln5-γ2 expression. Multivariate analysis revealed that high budding grade predicted poorer prognosis regardless of disease stage. Our results suggested that budding grade and Ln5-γ2 expression can be used as indicators of poor prognosis in patients with SCC of the EAC.

Urinary laminin-γ2 is a novel biomarker of non-muscle invasive urothelial carcinoma

Lack of appropriate biomarkers has hampered early detection of urothelial cancer (UC), therefore, development of biomarkers for its diagnosis at earlier stages is of importance. Laminin‐332 (Ln‐332, formerly Ln‐5), a component of basement membranes, consists of Ln‐α3, Ln‐β3, and Ln‐γ2 polypeptides. However, monomeric Ln‐γ2 alone is frequently expressed in malignant neoplasms. If Ln‐γ2 is also expressed in UC and secreted into the urine, its detection could be useful for UC diagnosis. Here, we evaluated Ln‐γ2 levels from 60 patients with urinary diseases (including UC) by Western blotting, and detected it in approximately 53% of UC cases. Using immunohistochemistry, we confirmed Ln‐γ2 expression in UC tissues that were positive for Ln‐γ2, whereas Ln‐α3 expression was absent. We next developed a sandwich enzyme‐linked immunosorbent assay and applied it for screening 39 patients with non‐muscle invasive UC and 61 patients with benign urologic diseases. The Ln‐γ2 levels were higher in UC patients than in those with benign urologic diseases. Ln‐γ2 was detected even in patients with earlier stages of UC, such as Ta, T1, or carcinoma in situ. The sensitivity of Ln‐γ2 testing for UC was 97.4%, and the specificity was 45.9%, using a cut‐off of 0.5 μg/g∙crn. Ln‐γ2 had greater diagnostic value for detecting non‐muscle invasive UC compared to conventional urine cytology and available biomarkers for UC, and may be useful as a urine biomarker for the diagnosis and monitoring of UC.

Clinical implications of N-cadherin expression in gastric cancer

Neo-expression of N-cadherin in cancer cells is regarded as a significant event in tumor progression via epithelial-mesenchymal transition (EMT). No reports have detailed the clinical impact of N-cadherin expression in gastric cancer. We retrospectively examined the co-expression of N-cadherin and E-cadherin in human gastric carcinoma and analyzed the clinicopathological significance of N-cadherin expression. One hundred and forty-six gastric cancer patients who received curative gastrectomy were enrolled. E-cadherin and N-cadherin immunoreactivity in cancer tissue was evaluated by the avidin-biotin-peroxidase complex technique. The correlation between N-cadherin and E-cadherin expression and clinicopathological parameters were analyzed. N-cadherin-positive and -negative expression were found in 31 and 115 patients, respectively. N-cadherin expression positively correlated with hematogenous recurrence (P < 0.01) and negatively correlated with patients' postoperative outcomes (P < 0.05). Moreover, only in the E-cadherin-preserved group was prognostic significance found according to N-cadherin expression (P < 0.01). We could not show a significant relationship between N-cadherin expression and EMT in gastric cancer. However, neo N-cadherin expression significantly affected patient's survival in gastric cancer. Therefore, we concluded that neo N-cadherin expression may be a useful prognostic marker independent of E-cadherin expression.

Laminin-5 immunohistochemical mapping for analysis of local extension in hypopharyngeal cancer: A preliminary report

OBJECTIVE

Laminin-5 γ2 chain (LNγ2) plays an important role in cancer differentiation and migration. Using a novel immunohistochemical mapping technique to investigate whole mucosal strips of total laryngopharyngectomy specimens using iodine, H-E, and LNγ2 stainings, we investigated the locoregional behavior of hypopharyngeal cancer.

METHODS

Surgical specimens from two patients with pyriform sinus cancer were investigated. Three percent iodine was applied to the tumor-bearing laryngopharynx during surgery and photographed. Stainabilities of H-E and LNγ2 on pathologic sections from all mucosal strips were scored and coordinated with the laryngopharyngeal photograph to illustrate the immunohistochemical map.

RESULTS

In both patients, the main tumor of invasive squamous cell carcinoma was circumferentially surrounded by a superficial lesion characterized by high grade intraepithelial neoplasia that remained unstained by iodine. On LNγ2 immunohistochemical mapping, the main tumor was demonstrated by Score 2 staining and the superficial lesion by a stronger Score 3 staining.

CONCLUSIONS

The finding of neoplastic cells at the periphery demonstrating a higher potential than the cancer cells at the tumor center is suggestive of impending progression from neoplasia to carcinoma. The current preliminary report suggested morphological evidence of intraepithelial infiltration and lateral invasion in hypopharyngeal cancer.

Expression of laminin 5-γ2 chain in cutaneous squamous cell carcinoma and its role in tumour invasion

Background:

Laminin-5 (Ln5), a heterotrimer composed of three chains (α3, β3, and γ2), is a major component of the basement membrane in most adult tissues. One of the chains, Ln5-γ2, is a marker of invasive tumours because it is frequently expressed as a monomer in malignant tumours. Recent studies from our laboratories detected higher levels of Ln5-γ2 expression in basal cell carcinoma (BCC) than in trichoblastoma. Furthermore, Ln5-γ2 overexpression tended to correlate with aggressiveness in BCC.

Methods:

In this study, we compared the expression of Ln5-γ2 in invasive squamous cell carcinoma (SCC, n=62) of the skin to that in preinvasive Bowen’s disease (BD, n=51), followed by analysis of the role of Ln5-γ2 in cancer invasion in vitro.

Results:

Immunohistochemically, the proportion of SCC cases (86%) strongly positive for Ln5-γ2 expression was higher than that of BD (16%). Real-time RT–PCR showed Ln5-γ2 overexpression in SCC cell line, A431, compared with normal keratinocyte cell line, HaCaT. Ln5-γ2 monomer and proteolytically cleaved, biologically active fragments of Ln5-γ2 were identified in SCC tumour extracts. In in vitro raft cultures, which simulate in vivo conditions, Ln5-γ2 siRNA significantly suppressed epidermal growth factor (EGF)-stimulated A431 cell invasion.

Conclusion:

Our results indicate that Ln5-γ2 has a role in cutaneous SCC invasion.

Laminin-121--recombinant expression and interactions with integrins

Laminin-121, previously referred as to laminin-3, was expressed recombinantly in human embryonic kidney (HEK) 293 cells by triple transfection of full-length cDNAs encoding mouse laminin α1, β2 and γ1 chains. The recombinant laminin-121 was purified using Heparin-Sepharose followed by molecular sieve chromatography and shown to be correctly folded by electron microscopy and circular dichroism (CD). The CD spectra of recombinant laminin-121 were very similar to those of laminin-111 isolated from Engelbreth-Holm-Swarm tumor (EHS-laminin) but its T(m) value was smaller than EHS-laminin and recombinant lamnin-111 suggesting that the replacement of the β chain reduced the stability of the coiled-coil structure of laminin-121. Its binding to integrins was compared with EHS-laminin, laminin-3A32 purified from murine epidermal cell line and recombinantly expressed laminins-111, -211 and -221. Laminin-121 showed the highest affinity to α6β1 and α7β1 integrins and furthermore, laminin-121 most effectively supported neurite outgrowth. Together, this suggests that the β2 laminins have higher affinity for integrins than the β1 laminins.

Light pulses administered during the circadian dark phase alter expression of cell cycle associated transcripts in mouse brain

The circadian mode of cell division has been known for more than a century, but the association between circadian rhythms and mitosis is not yet clear. Synchronization of circadian oscillators with the outside world is achieved because light, or other external temporal cues, have acute effects on the levels of the clock's molecular components. Thus, an important question is whether environmental signals also affect transcription levels of cell machinery genes in a similar manner? In a microarray analysis, we have tested the influence of light pulses on the expression of transcripts in the mouse brain. Light pulses consistently affect transcription levels of genes that are essential and directly control the cell cycle mechanism, as well as levels of genes that are associated with the various cell cycle checkpoints. The changes in the levels and the direction of these changes could possibly lead to cell cycle arrest. We also found consistent changes in transcription levels of genes that are associated with tumorigenesis and are directly implicated with enhanced proliferation and metastasis.

Regulated laminin-332 expression in human islets of Langerhans

Laminin-332 (LN-332) is a basement membrane component known to exert a beneficial effect on rat pancreatic beta cells in vitro. In this work, we analyzed the expression of LN-332 in human islets, its expression after inflammatory insults by cytokines, and the molecular mechanisms responsible for this effect. By Western blotting and RT-PCR, we showed that LN-332 was expressed in isolated human islets. By immunofluorescence on pancreas sections, we observed that labeling was confined to endocrine cells in islets. Confocal microscopy analysis on isolated islet cells revealed that labeling was granular but did not colocalize with hormone secretory granules. LN-332 was most abundant in cultured islets compared to freshly isolated islets and was found in culture medium, which suggests that it was secreted by islets. When islets were exposed to interleukin (IL)-1beta, expression and secretion of LN-332 increased as compared to control. No effect was observed with tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3-K) activity, inhibited culture- and IL-1beta-induced LN-332 expression in islets. These results show that LN-332, known to have some beneficial effect on beta cells in vitro, is produced and secreted by endocrine islet cells and is up-regulated by stressing conditions such as culture and IL-1beta-exposure.

Defining the role of laminin-332 in carcinoma

The deadly feature of cancer, metastasis, requires invasion of cells through basement membranes (BM), which normally act as barriers between tissue compartments. In the case of many epithelially-derived cancers (carcinomas), laminin-332 (Ln-332) is a key component of the BM barrier. This review provides a historical examination of Ln-332 from its discovery through identification of its functions in BM and possible role in carcinomas. Current understanding points to distinct roles for the three Ln-332 subunits (alpha3, beta3, gamma2) in cell adhesion, extracellular matrix stability, and cell signaling processes in cancer. Given the large number of studies linking Ln-332 gamma2 subunit with cancer prognosis, particular attention is given to the crucial role of this subunit in cancer invasion and to the unanswered questions in this area.