Laminin 5 gamma 2 chain expression: a marker of early invasiveness in colorectal adenomas

Knockdown of Atg7 Induces Nuclear-LC3 Dependent Apoptosis and Augments Chemotherapy in Colorectal Cancer Cells

Autophagy is a catabolic process that enables cells to degrade obsolete content and refuel energy depots. In colorectal cancer (CRC) autophagy has been shown to promote tumorigenesis through energy delivery in the condition of uncontrolled proliferation. With this study, we aimed at evaluating whether autophagy sustains CRC cell viability and if it impacts therapy resistance. Initially, a colorectal cancer tissue micro array, containing mucosa (n = 10), adenoma (n = 18) and adenocarcinoma (n = 49) spots, was stained for expression of essential autophagy proteins LC3b, Atg7, p62 and Beclin-1. Subsequently, central autophagy proteins were downregulated in CRC cells using siRNA technology. Viability assays, flow cytometry and immunoblotting were performed and three-dimensional cell culture was utilized to study autophagy in a tissue mimicking environment. In our study we found an upregulation of Atg7 in CRC. Furthermore, we identified Atg7 as crucial factor within the autophagy network for CRC cell viability. Its disruption induced cell death via triggering apoptosis and in combination with conventional chemotherapy it exerted synergistic effects in inducing CRC cell death. Cell death was strictly dependent on nuclear LC3b, since simultaneous knockdown of Atg7 and LC3b completely restored viability. This study unravels a novel cell death preventing function of Atg7 in interaction with LC3b, thereby unmasking a promising therapeutic target in CRC.

Vascular Invasion and Stromal S100A4 Expression at the Invasive Front of Colorectal Cancer are Novel Determinants and Tumor Prognostic Markers

Object: The aim of the present study was to investigate the clinicopathological characteristics and prognostic factors associated with sporadic colorectal cancer (CRC). We examined the clinicopathological findings and immunohistochemical expression of tumor prognostic markers at tumor budding sites to determine their predictive value for patient prognosis.

Materials and Methods: Immunohistochemical examination was performed by tissue microarray (TMA) of specimens from 106 patients with CRC. On hematoxylin and eosin (H&E)-stained tumor tissue slides, a representative area of tumor budding at the invasive front was selected for the construction of a TMA. Immunostaining for matrix metalloproteinase-7 (MMP7), the laminin-5 (ln-5) γ2 chain and S100A4 was performed to determine the association between patient survival and these markers.

Results: Clinicopathological variables were also assessed. Tumor location, histological type, degree of lymphatic invasion and vascular invasion, tumor stage, epithelial expression of S100A4, stromal cell expression of S100A4 and expression of the ln-5γ2 chain were associated with an increased risk of mortality. Five factors were retained in the multivariate logistic regression analysis. Specifically, the tumor location, degree of lymphatic invasion and vascular invasion, tumor stage and stromal cell expression of S100A4 remained significant predictors of patient survival after controlling for the other variables.

Conclusion: Vascular invasion and stromal expression of S100A4 in the tumor budding areas correlated with patient survival. Stromal immunostaining of S100A4 may be useful for identifying high-risk patients with advanced CRC.

Prognostic significance of circulating laminin gamma2 for early-stage non-small-cell lung cancer

Background

Laminin gamma2 (Ln-γ2) chain, a distinctive subunit of heterotrimeric laminin-332, is frequently upregulated in carcinomas and is of great importance in cell migration and invasion. Despite this, the status of circulating Ln-γ2 in lung cancer patients is still uncertain.

Patients and methods

In this retrospective study, serum samples from 538 all-stage (stages I–IV) patients with non-small-cell lung cancer (NSCLC) and 94 age-matched healthy volunteers were investigated by enzyme-linked immunosorbent assay. Data were statistically analyzed in combination with clinicopathological information.

Results

Circulating Ln-γ2 was markedly increased in NSCLC, even in stage I cases (P<0.01), reflecting the progression of lung cancer. Survival analysis on 370 eligible patients indicated that serum Ln-γ2-negative patients survived much longer compared with Ln-γ2-positive individuals (P=0.028), and it was especially the case for stage I (P<0.001), stage T1 (P=0.001), and stage N0 patients (P=0.038), all of whom represented early-stage cases. For the advanced patients, however, overall survivals were not significantly different among stages II–IV (P=0.830), stages T2–T4 (P=0.575), stages N1–N3 (P=0.669), and stage M1 (P=0.849). Cox analysis subsequently defined serum Ln-γ2 as an independent prognostic indicator of NSCLC, particularly for early-stage patients. Furthermore, we demonstrated the association of serum Ln-γ2 with smoking behavior, but its association with tumor progression and early prognostic significance were not altered in the nonsmoking cohort.

Conclusion

Our study demonstrated that elevation of circulating Ln-γ2 was an early-emerging event in NSCLC and was significantly associated with poor prognosis in NSCLC, especially for early-stage cases.

Colorectal cancer and basement membranes: clinicopathological correlations

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in males and the second in females. In 2008, an estimated 1.2 million people were diagnosed with and 608,700 people died of CRC. Besides diagnosis and treatment, prognosis is an important matter for cancer patients. Today, clinicopathological correlations have many applications in cancer prognostication. Examples include the prediction of the medium patient survival and the screening for patients suitable for specific therapeutic approaches. Apart from traditional prognostic factors, such as tumor stage and grade, new markers may be useful in clinical practice. Possible markers may result from the study of basement membranes (BMs). BM seems to play a role in the pathogenesis of colorectal cancer, so BM alterations may have prognostic significance as well. The purpose of this review is to briefly describe BMs and their relationship with CRC, in the aspect of clinicopathological correlations.

Immunohistochemical and molecular expression of laminin-332 gamma-2 chain in canine mammary tumors

Forty-eight cases of canine mammary cancer were investigated to evaluate the immunohistochemical distribution of the γ2 chain of laminin-332. Tumor cells were compared to a pool of normal mammary tissues using quantitative RT-PCR. The western blot was performed in eight tumor samples as complementary test to evaluate protein integrity. Immunohistochemistry experiments showed negative, focal, and weak expression of laminin-332 γ2 in tumors with the worst prognosis. Quantitative PCR revealed downregulation of the gene in 27 (56.2%) of the animals. Out of the 16 dogs with γ2 chain overexpression, seven were still alive. The western blot results showed bands generation of 36, 50, and 98kDa, suggesting degradation of laminin-332 γ2 in malignant tumors. The results suggest that, in the future, low expression and/or degradation of laminin-332 γ2 chain in canine mammary tumors may be used as an indicator of malignant potential. However, further studies are necessary to corroborate these results

Immunohistochemical evaluation of type IV collagen and laminin-332 γ2 chain expression in well-differentiated oral squamous cell carcinoma and oral verrucous carcinoma: a new recommended cut-off

BACKGROUND

Invasion and metastasis are two characteristics of malignant tumors, which perform by proteolytic destruction of the components of basement membrane (BM) and cell migration. The aim of this study was to evaluate the immunohistochemical (IHC) assessment of type IV collagen and laminin-332 γ2 (Ln-332 γ2) chain expression in well-differentiated oral squamous cell carcinoma (OSCC) and oral verrucous carcinoma (OVC), because these two lesions have same histopathologic findings whereas they have different biological behaviors.

METHODS

Destruction of BM and cell migration were evaluated by IHC in 15 cases of epithelial hyperplasia with no dysplasia (A group), 15 cases of OVC (B group) and 15 cases of well-differentiated OSCC (C group).

RESULTS

There was a significant difference in type IV collagen immunohistochemical staining between three groups, but there were no significant differences between B and C groups. Expression of Ln-332 γ2 chain was not detected in A group. Ln-332 γ2 chain labeling index had significantly difference between B and C groups. The number of Ln-332 γ2 chain immunostaining positive cells was less than 5% in B group and over than 5% in C group which there were significantly differences between these two groups.

CONCLUSIONS

Isolated immunohistochemical study of type IV collagen does not clearly define that a lesion is invasive or non-invasive and evaluation of Ln-332 γ2 chain expression (cut-off 5%) may be useful as a marker for description of biological differences and diagnosis of OVC from well-differentiated OSCC, especially in doubtful cases.

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.

The biological relevance of laminin 5gamma2 expression at the invading edge of colonic carcinomas

Previous studies have shown the presence of dilated neoplastic glands with cellular gaps called glandular pores (GPs) and laminin 5gamma2 expression at the invading edge of colonic carcinomas. We now extended our studies to explore a possible association between GP formation and laminin 5gamma2 expression at the invading edge of colonic carcinomas. Immunostain was performed on sections of five consecutive neoplastic glands with and without GPs from 86 colonic adenocarcinomas to assess the expression of laminin 5gamma2. Neoplastic glands with GPs were observed in 85% (73/86) of the tumors. Laminin 5gamma2 was expressed in 92% (335/365) of the neoplastic glands with GPs but only in 17% (63/365) of the neoplastic glands without GPs (p<0.05). Laminin 5gamma2 was overexpressed in the cells at the free ends of the pores in 88% of the neoplastic glands with GPs, but only in 14% of those without pores (p<0.05). Hence, at the growing edge of colonic carcinomas, laminin 5gamma2 was frequently expressed in neoplastic glands having GPs. Remarkably, the tumor cells at the free ends of the GPs overexpressed laminin 5gamma2, indicating increased production of this adhesion-migration macromolecule. The results suggest a close interaction between this adhesion-migration macromolecule, PG formation and the local progression of colonic carcinomas.

Tissue microarray analysis reveals a tight correlation between protein expression pattern and progression of esophageal squamous cell carcinoma

BACKGROUND

The development of esophageal squamous cell carcinoma (ESCC) progresses a multistage process, collectively known as precursor lesions, also called dysplasia (DYS) and carcinoma in situ (CIS), subsequent invasive lesions and final metastasis. In this study, we are interested in investigating the expression of a variety of functional classes of proteins in ESCC and its precursor lesions and characterizing the correlation of these proteins with ESCC malignant progression.

METHODS

Fas, FADD, caspase 8, CDC25B, fascin, CK14, CK4, annexin I, laminin-5gamma2 and SPARC were analyzed using immunohistochemistry on tissue microarray containing 205 ESCC and 173 adjacent precursor lesions as well as corresponding normal mucosa. To confirm the immunohistochemical results, three proteins, fascin, CK14 and laminin-5gamma2, which were overexpressed in ESCC on tissue microarray, were detected in 12 ESCC cell lines by Western blot assay.

RESULTS

In ESCC and its precursor lesions, FADD, CDC25B, fascin, CK14, laminin-5gamma2 and SPARC were overexpressed, while Fas, caspase 8, CK4 and annexin I were underexpressed. The abnormalities of these proteins could be classified into different groups in relation to the stages of ESCC development. They were "early" corresponding to mild and moderate DYS with overexpression of fascin, FADD and CDC25B and underexpression of Fas, caspase 8, CK4 and annexin I, "intermediate" to severe DYS and CIS with overexpression of FADD and CK14, and "late" to invasive lesions (ESCC) and to advanced pTNM stage ESCC lesions with overexpression of CK14, laminin-5gamma2 and SPARC.

CONCLUSION

Analyzing the protein expression patterns of Fas, FADD, caspase 8, CDC25B, fascin, CK14, CK4, annexin I, laminin-5gamma2 and SPARC would be valuable to develop rational strategies for early detection of lesions at risk in advance as well as for prevention and treatment of ESCC.

A keratinocyte hypermotility/growth-arrest response involving laminin 5 and p16INK4A activated in wound healing and senescence

Keratinocytes become migratory to heal wounds, during early neoplastic invasion, and when undergoing telomere-unrelated senescence in culture. All three settings are associated with expression of the cell cycle inhibitor p16INK4A (p16) and of the basement membrane protein laminin 5 (LN5). We have investigated cause-and-effect relationships among laminin 5, p16, hypermotility, and growth arrest. Plating primary human keratinocytes on the gamma2 precursor form of laminin 5 (LN5') immediately induced directional hypermotility at approximately 125 microm/hour, followed by p16 expression and growth arrest. Cells deficient in p16 and either p14ARF or p53 became hypermotile in response to LN5' but did not arrest growth. Plating on LN5' triggered smad nuclear translocation, and all LN5' effects were blocked by a transforming growth factor (TGF) beta receptor I (TGFbetaRI) kinase inhibitor. In contrast, plating cells on collagen I triggered a TGFbetaRI kinase-independent hypermotility unaccompanied by smad translocation or growth arrest. Plating on control surfaces with TGFbeta induced hypermotility after a 1-day lag time and growth arrest by a p16-independent mechanism. Keratinocytes serially cultured with TGFbetaRI kinase inhibitor exhibited an extended lifespan, and immortalization was facilitated following transduction to express the catalytic subunit of telomerase (TERT). These results reveal fundamental features of a keratinocyte hyper-motility/growth-arrest response that is activated in wound healing, tumor suppression, and during serial culture.

Co-expression of p16INK4A and laminin 5 by keratinocytes: a wound-healing response coupling hypermotility with growth arrest that goes awry during epithelial neoplastic progression

The replicative lifespan of human keratinocytes in culture is restricted by a telomere-unrelated induction of p16INK4A (p16) and p14ARF. We have found that, in vivo, p16 is expressed by epidermal and oral keratinocytes at the migrating fronts of healing wounds and at the stromal interface of severely dysplastic and early invasive lesions and that such cells also invariably display increased expression of Laminin 5 (Lam5). In culture, p16 and Lam5 are coexpressed in keratinocytes at senescence, at the edges of wounds made in confluent cultures, and when cells are plated on dishes coated with the gamma2 precursor form of Lam5 (Lam5gamma2pre). Lam5/p16 coexpression in all three in vitro settings is associated with directional hypermotility and growth arrest. Hypermotility and growth arrest are uncoupled in p16- and p14ARF/p53-deficient keratinocytes and squamous cell carcinoma (SCC) cells; such cells become hypermotile is response to Lam5gamma2pre but do not growth arrest. Thus, the Lam5/p16 response is activated in normal wound healing, causing growth arrest of migratory keratinocytes that lead wound reepithelialization. This response also becomes activated at a critical stage of neoplastic progression, acting as a tumor suppressor mechanism. Rare premalignant cells that lose p16 remain motile and proliferative, thereby resulting in invasive growth as SCC.

Mechanisms involved in ultraviolet light-induced immunosuppression

Ultraviolet light (UV) represents one of the most relevant environmental factors influencing humans, especially with regard to its hazardous health effects, which include premature skin aging, skin cancer, and exacerbation of infectious diseases. Several of these effects are mediated by the immunosuppressive properties of UV. UV can compromise the immune system in several ways, e.g., by affecting the function of antigen-presenting cells, inducing the release of cytokines, and modulating the expression of surface molecules. Recently a link between UV-induced immunosuppression and apoptosis was recognized. In the following, the basic mechanisms underlying UV-induced immunosuppression will be discussed.