L1 cell adhesion molecule (L1CAM) in invasive tumors

Angiogenic cytokines are antibody targets during graft-versus-leukemia reactions

PURPOSE

The graft-versus-leukemia (GVL) reaction is an important example of immune-mediated tumor destruction. A coordinated humoral and cellular response accomplishes leukemia cell killing, but the specific targets remain largely uncharacterized. To learn more about the antigens that elicit antibodies during GVL reactions, we analyzed patients with advanced myelodysplasia (MDS) and acute myelogenous leukemia (AML) who received an autologous, granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell vaccine early after allogeneic hematopoietic stem cell transplantation (HSCT).

EXPERIMENTAL DESIGN

A combination of tumor-derived cDNA expression library screening, protein microarrays, and antigen-specific ELISAs were used to characterize sera obtained longitudinally from 15 patients with AML/MDS who were vaccinated early after allogeneic HSCT.

RESULTS

A broad, therapy-induced antibody response was uncovered, which primarily targeted intracellular proteins that function in growth, transcription/translation, metabolism, and homeostasis. Unexpectedly, antibodies were also elicited against eight secreted angiogenic cytokines that play critical roles in leukemogenesis. Antibodies to the angiogenic cytokines were evident early after therapy, and in some patients manifested a diversification in reactivity over time. Patients that developed antibodies to multiple angiogenic cytokines showed prolonged remission and survival.

CONCLUSIONS

These results reveal a potent humoral response during GVL reactions induced with vaccination early after allogeneic HSCT and raise the possibility that antibodies, in conjunction with natural killer cells and T lymphocytes, may contribute to immune-mediated control of myeloid leukemias.

Cancer stem cells in basic science and in translational oncology: can we translate into clinical application?

Since their description and identification in leukemias and solid tumors, cancer stem cells (CSC) have been the subject of intensive research in translational oncology. Indeed, recent advances have led to the identification of CSC markers, CSC targets, and the preclinical and clinical evaluation of the CSC-eradicating (curative) potential of various drugs. However, although diverse CSC markers and targets have been identified, several questions remain, such as the origin and evolution of CSC, mechanisms underlying resistance of CSC against various targeted drugs, and the biochemical basis and function of stroma cell-CSC interactions in the so-called ‘stem cell niche.’ Additional aspects that have to be taken into account when considering CSC elimination as primary treatment-goal are the genomic plasticity and extensive subclone formation of CSC. Notably, various cell fractions with different combinations of molecular aberrations and varying proliferative potential may display CSC function in a given neoplasm, and the related molecular complexity of the genome in CSC subsets is considered to contribute essentially to disease evolution and acquired drug resistance. In the current article, we discuss new developments in the field of CSC research and whether these new concepts can be exploited in clinical practice in the future.

The Robustness of Pathway Analysis in Identifying Potential Drug Targets in Non-Small Cell Lung Carcinoma

The identification of genes responsible for causing cancers from gene expression data has had varied success. Often the genes identified depend on the methods used for detecting expression patterns, or on the ways that the data had been normalized and filtered. The use of gene set enrichment analysis is one way to introduce biological information in order to improve the detection of differentially expressed genes and pathways. In this paper we show that the use of network models while still subject to the problems of normalization is a more robust method for detecting pathways that are differentially overrepresented in lung cancer data. Such differences may provide opportunities for novel therapeutics. In addition, we present evidence that non-small cell lung carcinoma is not a series of homogeneous diseases; rather that there is a heterogeny within the genotype which defies phenotype classification. This diversity helps to explain the lack of progress in developing therapies against non-small cell carcinoma and suggests that drug development may consider multiple pathways as treatment targets.

L1 cell adhesion molecule expression is associated with pelvic lymph node metastasis and advanced stage in diabetic patients with endometrial cancer: a matched case control study

Background:

Diabetic patients with endometrial cancer had more lymph node metastasis than non-diabetic patients with endometrial cancer. L1 cell adhesion molecule (L1CAM) could be possibly associated with lymph node metastasis in diabetic patients with endometrial cancer via epithelial-mesenchymal transition. We aimed to investigate the association between L1CAM expression and lymph node metastasis in diabetic patients with endometrial cancer.

Methods:

We conducted a matched case control study of 68 endometrial cancer patients who comprise each 34 diabetic and non-diabetic patients. L1CAM expression was evaluated by immunohistochemistry using fresh formalin-fixed paraffin-embedded tissue block of the patients. The association between L1CAM expression and pelvic lymph node metastasis was assessed according to the presence of diabetes.

Results:

Of the 68 patients, 13 (19.1%) were positive for L1CAM immunostaining. Positive rate of L1CAM expression in diabetic endometrial cancer patients was similar to that in non-diabetic endometrial cancer patients (14.7% vs. 23.5%, P = 0.355). Tumor recurred more frequently in patients with positive L1CAM expression than those with negative L1CAM expression (33.3% vs. 1.6%, P = 0.019). However, we failed to find any significant association between L1CAM expression and lymph node metastasis. Only for the diabetic patients (n = 34), patients with pelvic lymph node metastasis had more L1CAM expression than those without lymph node metastasis (50.0% vs. 3.6%, P = 0.035). Advanced stage was the only risk factor for recurrence that showed a significant association with L1CAM expression for the diabetic endometrial cancer patients (P = 0.006), as well as all the enrolled patients (P = 0.014).

Conclusion:

L1CAM expression is associated with pelvic lymph node metastasis and advanced stage in diabetic patients with endometrial cancer.

The ubiquitous neural cell adhesion molecule (N-CAM)

Adhesive interactions are important for cell trafficking, differentiation, function and tissue differentiation. Neural cell adhesion molecule (NCAM) is involved in a diverse range of contact-mediated interactions among neurons, astrocytes, oligodendrocytes, and myotubes. It is widely but transiently expressed in many tissues early in embryogenesis. Four main isoforms exist but there are many other variants resulting from alternative splicing and post-translational modifications. This review discusses the actions and association of N-CAM and variants, PSA CAM. L1CAM and receptor tyrosine kinase. Their interactions with the interstitial cells of Cajal – the pacemaker cells of the gut in the manifestation of gut motility disorders, expression in carcinomas and mesenchymal tumours are discussed.

Anti-L1CAM radioimmunotherapy is more effective with the radiolanthanide terbium-161 compared to lutetium-177 in an ovarian cancer model

PURPOSE

The L1 cell adhesion molecule (L1CAM) is considered a valuable target for therapeutic intervention in different types of cancer. Recent studies have shown that anti-L1CAM radioimmunotherapy (RIT) with (67)Cu- and (177)Lu-labelled internalising monoclonal antibody (mAb) chCE7 was effective in the treatment of human ovarian cancer xenografts. In this study, we directly compared the therapeutic efficacy of anti-L1CAM RIT against human ovarian cancer under equitoxic conditions with the radiolanthanide (177)Lu and the potential alternative (161)Tb in an ovarian cancer therapy model.

METHODS

Tb was produced by neutron bombardment of enriched (160)Gd targets. (161)Tb and (177)Lu were used for radiolabelling of DOTA-conjugated antibodies. The in vivo behaviour of the radioimmunoconjugates (RICs) was assessed in IGROV1 tumour-bearing nude mice using biodistribution experiments and SPECT/CT imaging. After ascertaining the maximal tolerated doses (MTD) the therapeutic impact of 50 % MTD of (177)Lu- and (161)Tb-DOTA-chCE7 was evaluated in groups of ten mice by monitoring the tumour size of subcutaneous IGROV1 tumours.

RESULTS

The average number of DOTA ligands per antibody was 2.5 and maximum specific activities of 600 MBq/mg were achieved under identical radiolabelling conditions. RICs were stable in human plasma for at least 48 h. (177)Lu- and (161)Tb-DOTA-chCE7 showed high tumour uptake (37.8-39.0 %IA/g, 144 h p.i.) with low levels in off-target organs. SPECT/CT images confirmed the biodistribution data. (161)Tb-labelled chCE7 revealed a higher radiotoxicity in nude mice (MTD: 10 MBq) than the (177)Lu-labelled counterpart (MTD: 12 MBq). In a comparative therapy study with equitoxic doses, tumour growth inhibition was better by 82.6 % for the (161)Tb-DOTA-chCE7 than the (177)Lu-DOTA-chCE7 RIT.

CONCLUSIONS

Our study is the first to show that anti-L1CAM (161)Tb RIT is more effective compared to (177)Lu RIT in ovarian cancer xenografts. These results suggest that (161)Tb is a promising candidate for future clinical applications in combination with internalising antibodies.

Overexpression of L1CAM is associated with tumor progression and prognosis via ERK signaling in gastric cancer

BACKGROUND

L1 cell adhesion molecule (L1CAM), which belongs to the immunoglobulin superfamily, has recently been observed in a variety of human malignancies. However, its clinical implication in gastric cancer remains unclear. The aim of this study was to explore the role of L1CAM in gastric cancer and to analyze its correlation with tumor progression and prognosis.

METHODS

L1CAM expression was measured in human gastric cancer cell lines and knockdown was conducted using siRNA. Cell proliferation, invasion and migration ability was assessed in vitro. The downstream pathway of L1CAM was explored by western blot analysis. L1CAM expression was measured in 112 pairs of human gastric cancer and adjacent noncancerous tissues using real-time quantitative RT-PCR, and the correlation with clinicopathological features and prognosis was analyzed.

RESULTS

L1CAM downregulation by siRNA significantly decreased cell proliferation, migration, and invasion in gastric cancer cell lines. Phosphorylated ERK levels began to decline more rapidly in L1CAM knockdown cells compared with parental cells. L1CAM overexpression was significantly correlated with local tumor cell growth (P = 0.041), distant metastasis (P = 0.047), and tumor stage (P = 0.031). The overall survival in patients with high L1CAM expression was significantly shorter than that of patients with low L1CAM expression (P = 0.02).

CONCLUSIONS

L1CAM overexpression may be a critical prognostic factor in patients with gastric cancer, and was strongly associated with tumor proliferation, migration, and invasion through the ERK pathway. L1CAM might be an attractive therapeutic molecular target for the treatment of gastric cancer patients.

L1 and epithelial cell adhesion molecules associated with gastric cancer progression and prognosis in examination of specimens from 601 patients

Background

L1 cell adhesion molecule (L1CAM) and epithelial cell adhesion molecule (EPCAM) have been implicated in the development and progression of gastric cancer. The present study investigated the clinical significance of L1CAM and EPCAM in the development, progression and prognosis of gastric cancer.

Methods

Expression of L1CAM and EPCAM were examined immunochemically in 601 clinicopathologically characterized gastric cancer cases.

Results

L1CAM protein was detected in 23.9% of human non-tumor mucosa samples. All samples expressed L1CAM protein at low levels. High expression of L1CAM protein was detected in 163 (27.1%) tumors. Expression of L1CAM correlated with age, tumor location, size of tumors, Lauren’s classification, depth of invasion, lymph node and distant metastases, regional lymph node stage, Tumor-Node-Metastasis (TNM) stage and prognosis. EPCAM protein was detected in 45.7% of human non-tumor mucosa samples. All samples expressed EPCAM protein at low levels. High expression of EPCAM protein was detected in 247 (41.1%) tumors. Expression of EPCAM correlated with age, tumor location, size of tumors, Lauren’s classification, depth of invasion, lymph node and distant metastases, regional lymph node stage, TNM stage and prognosis. Cumulative 5-year survival rates of patients with high expression of both L1CAM and EPCAM were significantly lower than in patients with low expression of both.

Conclusions

Expression of L1CAM and EPCAM in gastric cancer was significantly associated with lymph node and distant metastasis, and poor prognosis. L1CAM and EPCAM proteins could be useful markers to predict tumor progression and prognosis.

Role of L1 cell adhesion molecule (L1CAM) in the metastatic cascade: promotion of dissemination, colonization, and metastatic growth

Expression of the L1 cell adhesion molecule (L1CAM) is frequently increased in cancer patients compared to healthy individuals and also linked with bad prognosis of solid tumours. Previously, we could show that full-length L1CAM promotes metastasis formation via up-regulation of gelatinolytic activity in fibrosarcoma. In this study, we aimed to extend this finding to haematogenous malignancies and carcinomas, and to specifically elucidate the impact of L1CAM on major steps of the metastatic cascade. In a well-established T-cell lymphoma spontaneous metastasis model, silencing of L1CAM significantly improved survival of the mice, while intradermal tumour growth remained unaltered. This correlated with significantly decreased spontaneous metastasis formation. L1CAM suppression abrogated the metastatic potential of T-cell lymphoma as well as carcinoma cells as demonstrated by reduced migration and invasion in vitro and reduced formation of experimental metastasis in vivo. At the molecular level, silencing of L1CAM led to reduced expression of gelatinases MMP-2 and -9 in vitro and decreased gelatinolytic activity in primary tumours and metastases in vivo. In accordance, knock down of L1CAM had similar suppressive effects on migration, invasion and in vivo-gelatinolytic activity as treatment with the specific gelatinase inhibitor SB-3CT. This newly discovered impact of L1CAM on distinct steps of the metastatic cascade and MMP activity highlights the potential of possible L1CAM-directed therapies to inhibit metastatic spread.

CHL1 is involved in human breast tumorigenesis and progression

Neural cell adhesion molecules (CAM) play important roles in the development and regeneration of the nervous system. The L1 family of CAMs is comprised of L1, Close Homolog of L1 (CHL1, L1CAM2), NrCAM, and Neurofascin, which are structurally related trans-membrane proteins in vertebrates. Although the L1CAM has been demonstrated play important role in carcinogenesis and progression, the function of CHL1 in human breast cancer is limited. Here, we found that CHL1 is down-regulated in human breast cancer and related to lower grade. Furthermore, overexpression of CHL1 suppresses proliferation and invasion in MDA-MB-231 cells and knockdown of CHL1 expression results in increased proliferation and invasion in MCF7 cells in vitro. Finally, CHL1 deficiency promotes tumor formation in vivo. Our results may provide a strategy for blocking breast carcinogenesis and progression.

RAF kinase inhibitor-independent constitutive activation of Yes-associated protein 1 promotes tumor progression in thyroid cancer

The transcription coactivator Yes-associated protein 1 (YAP1) is regulated by the Hippo tumor suppressor pathway. However, the role of YAP1 in thyroid cancer, which is frequently associated with the BRAF^V600E mutation, remains unknown. This study aimed to investigate the role of YAP1 in thyroid cancer. YAP1 was overexpressed in papillary (PTC) and anaplastic thyroid cancer, and nuclear YAP1 was more frequently detected in BRAF^V600E (+) PTC. In the thyroid cancer cell lines TPC-1 and HTH7, which do not have the BRAF^V600E mutation, YAP1 was cytosolic and inactive at high cell densities. In contrast, YAP1 was retained in the nucleus and its target genes were expressed in the thyroid cancer cells 8505C and K1, which harbor the BRAF^V600E mutation, regardless of cell density. Furthermore, the nuclear activation of YAP1 in 8505C was not inhibited by RAF or MEK inhibitor. In vitro experiments, YAP1 silencing or overexpression affected migratory capacities of 8505C and TPC-1 cells. YAP1 knockdown resulted in marked decrease of tumor volume, invasion and distant metastasis in orthotopic tumor xenograft mouse models using the 8505C thyroid cancer cell line. Taken together, YAP1 is involved in the tumor progression of thyroid cancer and YAP1-mediated effects might not be affected by the currently used RAF kinase inhibitors.

LKB1 represses focal adhesion kinase (FAK) signaling via a FAK-LKB1 complex to regulate FAK site maturation and directional persistence

Liver kinase β1 (LKB1, also known as STK11) is a serine/threonine kinase that has multiple cellular functions including the regulation of cell polarity and motility. Murine proteomic studies show that LKB1 loss causes aberrant adhesion signaling; however, the mechanistic underpinnings of this relationship are unknown. We show that cells stably depleted of LKB1 or its co-activator STRADα have increased phosphorylation of focal adhesion kinase (FAK) at Tyr(397)/Tyr(861) and enhanced adhesion to fibronectin. LKB1 associates in a complex with FAK and LKB1 accumulation at the cellular leading edge is mutually excluded from regions of activated Tyr(397)-FAK. LKB1-compromised cells lack directional persistence compared with wild-type cells, but this is restored through subsequent pharmacological FAK inhibition or depletion, showing that cell directionality is mediated through LKB1-FAK signaling. Live cell confocal imaging reveals that LKB1-compromised cells lack normal FAK site maturation and turnover, suggesting that defects in adhesion and directional persistence are caused by aberrant adhesion dynamics. Furthermore, re-expression of full-length wild-type or the LKB1 N-terminal domain repressed FAK activity, whereas the kinase domain or C-terminal domain alone did not, indicating that FAK suppression is potentially regulated through the LKB1 N-terminal domain. Based upon these results, we conclude that LKB1 serves as a FAK repressor to stabilize focal adhesion sites, and when LKB1 function is compromised, aberrant FAK signaling ensues, resulting in rapid FAK site maturation and poor directional persistence.

Wnt signaling: role in Alzheimer disease and schizophrenia

Wnt signaling function starts during the development of the nervous system and is crucial for synaptic plasticity in the adult brain. Clearly Wnt effects in synaptic and plastic processes are relevant, however the implication of this pathway in the prevention of neurodegenerative diseases that produce synaptic impairment, is even more interesting. Several years ago our laboratory found a relationship between the loss of Wnt signaling and the neurotoxicity of the amyloid-β-peptide (Aβ), one of the main players in Alzheimer's disease (AD). Moreover, the activation of the Wnt signaling cascade prevents Aβ-dependent cytotoxic effects. In fact, disrupted Wnt signaling may be a direct link between Aβ-toxicity and tau hyperphosphorylation, ultimately leading to impaired synaptic plasticity and/or neuronal degeneration, indicating that a single pathway can account for both neuro-pathological lesions and altered synaptic function. These observations, suggest that a sustained loss of Wnt signaling function may be a key relevant factor in the pathology of AD. On the other hand, Schizophrenia remains one of the most debilitating and intractable illness in psychiatry. Since Wnt signaling is important in organizing the developing brain, it is reasonable to propose that defects in Wnt signaling could contribute to Schizophrenia, particularly since the neuro-developmental hypothesis of the disease implies subtle dys-regulation of brain development, including some core components of the Wnt signaling pathways such as GSK-3β or Disrupted in Schizophrenia-1 (DISC-1). This review focuses on the relationship between Wnt signaling and its potential relevance for the treatment of neurodegenerative and neuropsychiatric diseases including AD and Schizophrenia.

Deregulated microRNAs identified in isolated glioblastoma stem cells: an overview

Glioblastoma multiforme (GBM), the most common and aggressive primary brain tumor, is extremely resistant to current treatment paradigms and has a high rate of tumor recurrence. Recent progress in the field of tumor-initiating cells suggests that GBM stem cells (GBMSCs) may be responsible for tumor progression, resistance to treatment, and tumor relapse. Therefore, understanding the biologically significant pathways involved in modulating GBMSC-specific characteristics offers great promise for development of novel therapeutics, which may improve therapeutic efficacy and overcome present drug resistance. In addition, targeting deregulated microRNA (miRNA) has arisen as a new therapeutic strategy in treating malignant gliomas. In GBMSCs, miRNAs regulate a wide variety of tumorigenic processes including cellular proliferation, stemness maintenance, migration/invasion, apoptosis, and tumorigenicity. Nevertheless, the latest progress with GBMSCs and subsequent miRNA profiling is limited by the identification and isolation of GBMSCs. In this review, we thus summarize current markers and known features for isolation as well as the aberrant miRNAs that have been identified in GBM and GBMSCs.

Comparison of L1 expression and secretion in glioblastoma and neuroblastoma cells

The expression of cell adhesion molecule L1 has been identified in a vast spectrum of tumors; however, its expression pattern with regard to tumor type is rarely discussed. In the present study, we studied L1 levels in human glioblastomas and neuroblastomas, and compared the expression and secretion of L1 in human glioblastoma U87-MG and neuroblastoma SK-N-SH cells. Immunofluorescence staining revealed different grades of L1 staining in human glioblastoma and neuroblastoma samples. In U87-MG cells, full-length L1 was weakly detected in cell lysates (CLs), while greater levels of abundant soluble L1 were confined in conditioned culture medium (CCM). In contrast, higher levels of full-length L1 were confined in SK-N-SH CLs, while almost no soluble forms of L1 were detected in CCM. Our data indicates various expression patterns of L1 in U87-MG and SK-N-SH cells, which may underlie the different malignancies of the two neural tumor types and further stress the importance of soluble L1-mediated signaling pathways in cell malignancy.

The neural adhesion molecule L1CAM confers chemoresistance in human glioblastomas

Glioblastoma multiforme (GBM) represents the most common and malignant brain tumor. GBM tissues exhibit elevated expression of the transforming growth factor-beta1 (TGF-β1) and the adhesion molecule L1CAM. This study investigated the mechanism of L1CAM regulation in GBM cells and its role in the mediation of chemoresistance. L1CAM expression levels varied in GBM cells being highest in A172 cells and low in T98G cells. Inhibition of TGF-β1 signaling in A172 cells reduced L1CAM expression and vice versa stimulation with exogenous TGF-β1 led to upregulation of L1CAM in T98G cells. Additionally, TGF-β1 and L1CAM expression increased during differentiation of glioma stem-like cells. L1CAM expressing GBM cells and differentiated glioma stem-like cells showed a reduced apoptotic response after treatment with the chemotherapeutic drug temozolomide. Accordingly, siRNA-mediated knock-down of L1CAM in A172 cells and differentiated glioma stem-like cells increased chemosensitivity, whereas overexpression of L1CAM in T98G cells and glioma spheroids diminished the apoptotic response. Elevated L1CAM expression caused a diminished expression of caspase-8 in GBM and differentiated glioma stem-like cells. These data show that TGF-β1 dependent upregulation of L1CAM expression in GBM cells leads to the downregulation of caspase-8 and apoptosis resistance pointing to L1CAM as potential target for improved therapy of GBM patients.

A chimeric antibody to L1 cell adhesion molecule shows therapeutic effect in an intrahepatic cholangiocarcinoma model

Intrahepatic cholangiocarcinoma (ICC), a malignant tumor derived from the intrahepatic bile duct epithelium, has a poor prognosis and is refractory to conventional chemotherapy and radiation therapy. Thus, there is an urgent need to develop new effective therapeutic strategies for this disease. We previously found that L1 cell adhesion molecule (L1CAM) plays an important role in tumor progression of ICC, and we generated a murine mAb, A10-A3 (IgG1), that binds to the Ig1 domain of L1CAM. In the present study, we further characterized A10-A3, constructed a chimeric A10-A3 antibody (cA10-A3) containing the constant regions of human IgG1, and evaluated the therapeutic potential in a human ICC xenograft nude mice model. The affinities (KD) of A10-A3 and cA10-A3 for soluble L1CAM were 1.8 nM and 1.9 nM, respectively, as determined by competition ELISA. A10-A3 inhibited L1CAM homophilic binding and was slowly internalized into the tumor cells, but it did not significantly inhibit proliferation of ICC cells in vitro. cA10-A3 mediated antibody- dependent cell-mediated cytotoxicity in vitro and displayed anti-tumor activity in the ICC animal model. These results suggest that the humanized A10-A3 antibody may have potential as an anticancer agent for the treatment of ICC.

L1 cell adhesion molecule overexpression in hepatocellular carcinoma associates with advanced tumor progression and poor patient survival

Objective

L1 cell adhesion molecule (L1CAM), as a member of the immunoglobulin superfamily, has recently been observed in a variety of human malignancies. However, no data of L1CAM are available for hepatocellular carcinoma (HCC). The aim of this study was to investigate the expression of L1CAM in HCC and determine its correlation with tumor progression and prognosis.

Methods

One-hundred and thirty HCC patients who had undergone curative liver resection were selected and immunohistochemistry, Western blotting, and quantitative real time polymerase chain reaction (Q-PCR) were performed to analyze L1CAM expression in the respective tumors.

Results

Immunohistochemistry, Western blotting, and Q-PCR consistently confirmed the overexpression of L1CAM in HCC tissues compared with their adjacent nonneoplastic tissues at both protein and gene level (both P <0.01). Additionally, the high expression of L1CAM was significantly associated with advanced tumor stage (P = 0.02) and advanced tumor grade (P = 0.03), respectively. Moreover, HCC patients with high L1CAM expression were significantly associated with lower 5-year overall survival (P <0.01) and lower 5-year disease-free survival (P <0.01), respectively. The Cox proportional hazards model further showed that L1CAM over-expression was an independent poor prognostic factor for both 5-year disease-free survival (P = 0.02) and 5-year overall survival (P = 0.008) in HCC.

Conclusion

Our data suggest for the first time that L1CAM expression in HCC was significantly correlated with the advanced tumor progression and was an independent poor prognostic factor for both overall survival and disease-free survival in patients with HCC.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1970024872761542

microRNA-146a targets the L1 cell adhesion molecule and suppresses the metastatic potential of gastric cancer

Recent studies have shown that microRNA-146a (miR-146a) is associated with cancer metastasis. However, the mechanisms underlying this process remain poorly understood. In this study, we aimed to investigate the potential role of miR-146a in gastric cancer metastasis. A wound-healing assay and a Transwell assay were used to investigate the impact of miR-146a on the migratory and invasive abilities of MKN-45 cells in vitro. MKN-45 cells stably expressing miR-146a or the negative control were transplanted into nude mice through the lateral tail vein to explore the effect of miR-146a on tumor metastasis in vivo. A luciferase reporter assay and western blot analysis were used to identify the potential target genes. Our results show that the overexpression of miR-146a inhibits the invasion and metastasis of MKN-45 cells in vitro and in vivo. Furthermore, the L1 cell adhesion molecule (L1CAM) was identified as a novel target of miR‑146a in gastric cancer. Taken together, our results provide evidence that miR-146a suppresses gastric cancer cell invasion and metastasis in vitro and in vivo, which may be in part due to the downregulation of L1CAM. miR-146a may have the therapeutic potential to suppress gastric cancer metastasis.

MicroRNA-10a targets CHL1 and promotes cell growth, migration and invasion in human cervical cancer cells

MicroRNAs (miRNAs) play an important role in cancer initiation, progression and metastasis by regulating their target genes. Here, we found microRNA-10a (miR-10a) is upregulated in human cervical cancer and promotes the colony formation activity, migration and invasion of HeLa and C33A cells. Subsequently, CHL1 is confirmed as a target of miR-10a and is negatively regulated by miR-10a at mRNA and protein levels. Furthermore, knockdown of CHL1 expression results in increased colony formation activity, migration and invasion. Finally, overexpression of CHL1 lacked the 3'UTR abolished the effects of miR-10a. Our results may provide a strategy for blocking tumor metastasis.

Transcriptional signatures of Ral GTPase are associated with aggressive clinicopathologic characteristics in human cancer

RalA and RalB are small GTPases that support malignant development and progression in experimental models of bladder, prostate, and squamous cancer. However, demonstration of their clinical relevance in human tumors remains lacking. Here, we developed tools to evaluate Ral protein expression, activation, and transcriptional output and evaluated their association with clinicopathologic parameters in common human tumor types. To evaluate the relevance of Ral activation and transcriptional output, we correlated RalA and RalB activation with the mutational status of key human bladder cancer genes. We also identified and evaluated a transcriptional signature of genes that correlates with depletion of RalA and RalB in vivo. The Ral transcriptional signature score, but not protein expression as evaluated by immunohistochemistry, predicted disease stage, progression to muscle invasion, and survival in human bladder cancers and metastatic and stem cell phenotypes in bladder cancer models. In prostate cancer, the Ral transcriptional signature score was associated with seminal vesicle invasion, androgen-independent progression, and reduced survival. In squamous cell carcinoma, this score was decreased in cancer tissues compared with normal mucosa, validating the experimental findings that Ral acts as a tumor suppressor in this tumor type. Together, our findings show the clinical relevance of Ral in human cancer and provide a rationale for the development of Ral-directed therapies.

Aberrant l1 cell adhesion molecule affects tumor behavior and chemosensitivity in anaplastic thyroid carcinoma

PURPOSE

Anaplastic thyroid carcinoma (ATC) is one of the most invasive human cancers and has a poor prognosis. Molecular targets of ATC that determine its highly aggressive nature remain unidentified. This study investigated L1 cell adhesion molecule (L1CAM) expression and its role in tumorigenesis of ATCs.

EXPERIMENTAL DESIGN

Expression of L1CAM in thyroid cancer was evaluated by immunohistochemical analyses of tumor samples from patients with thyroid cancer. We investigated the role of L1CAM in proliferation, migration, invasion, and chemoresistance using short hairpin RNA (shRNA) knockdown experiments in human ATC cell lines. Finally, we evaluated the role of L1CAM on tumorigenesis with ATC xenograft assay in a nude mouse model.

RESULTS

L1CAM expression was not detectable in normal follicular epithelial cells of the thyroid or in differentiated thyroid carcinoma. In contrast, analysis of ATC samples showed specifically higher expression of L1CAM in the invasive area of the tumor. Specific knockdown of L1CAM in the ATC cell lines, FRO and 8505C, caused a significant decrease in the proliferative, migratory, and invasive capabilities of the cells. Suppression of L1CAM expression in ATC cell lines increased chemosensitivity to gemcitabine or paclitaxel. Finally, in an ATC xenograft model, depletion of L1CAM markedly reduced tumor growth and increased the survival of tumor-bearing mice.

CONCLUSIONS

We report that L1CAM is highly expressed in the samples taken from patients with ATCs. L1CAM plays an important role in determining tumor behavior and chemosensitivity in cell lines derived from ATCs. Therefore, we suggest that L1CAM may be an important therapeutic target in patients with ATCs.

Characteristic features of stem cells in glioblastomas: from cellular biology to genetics

Glioblastoma is the most common type of primary brain tumor in adults and is among the most lethal and least successfully treated solid tumors. Recently, research into the area of stem cells in brain tumors has gained momentum. However, due to the relatively new and novel hypothesis that a subpopulation of cancer cells in each malignancy has the potential for tumor initiation and repopulation, the data in this area of research are still in its infancy. This review article is aimed at attempting to bring together research carried out so far in order to build an understanding of glioblastoma stem cells (GSCs). Initially, we consider GSCs at a morphological and cellular level, and then discuss important cell markers, signaling pathways and genetics. Furthermore, we highlight the difficulties associated with what some of the evidence indicates and what collectively the studies contribute to further defining the interpretation of GSCs.

Dual REST-dependence of L1CAM: from gene expression to alternative splicing governed by Nova2 in neural cells

L1 cell adhesion molecule (L1CAM), an adhesion/signaling protein encoded by a gene target of the transcription repressor RE-1-Silencing Transcription factor (REST), is expressed in two alternatively spliced isoforms. The full-length isoform, typical of low-REST neural cells, plays key roles in survival/migration, outgrowth/fasciculation/regeneration of axons, synaptic plasticity; the isoform missing two mini-exons, abundant in a few high-REST non-neural cells, maintains some effect on migration and proliferation. To investigate whether and how L1CAM alternative splicing depends on REST we used neural cell models expressing low or high levels of REST (PC12, SH-SY5Y, differentiated NT2/D1 and primary neurons transduced or not with REST). The short isoform was found to rise when the low-REST levels of neural cells were experimentally increased, while the full-length isoform increased in high-REST cells when the repressor tone was attenuated. These results were due to Nova2, a neural cell-specific splicing factor shown here to be repressed by REST. REST control of L1CAM occurs therefore by two mechanisms, transcription and alternative splicing. The splicing mechanism, affecting not only L1CAM but all Nova2 targets (∼7% of brain-specific splicing, including the mRNAs of other adhesion and synaptic proteins) is expected to be critical during development and important also for the structure and function of mature neural cells.

Prognostic significance of L1CAM in ovarian cancer and its role in constitutive NF-κB activation

BACKGROUND

Overexpression of L1-cell adhesion molecule (L1CAM) has been observed for various carcinomas and correlates with poor prognosis and late-stage disease. In vitro, L1CAM enhances proliferation, cell migration, adhesion and chemoresistance. We tested L1CAM and interleukin-1 beta (IL-1β) expression in tumor samples and ascitic fluid from ovarian carcinoma patients to examine its role as a prognostic marker.

PATIENTS AND METHODS

We investigated tumor samples and ascitic fluid from 232 serous ovarian carcinoma patients for L1CAM by enzyme-linked immunosorbent assay. L1CAM expression was correlated with pathoclinical parameters and patients' outcome. IL-1β levels were measured in tumor cell lysates. Ovarian cancer cell lines were analyzed for the contribution of L1CAM to IL-1β production and nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NF-κB) activation.

RESULTS

We observed that L1CAM-expressing tumors show a highly invasive phenotype associated with restricted tumor resectability at primary debulking surgery and increased lymphogenic spread. Soluble L1CAM proved to be a marker for poor progression-free survival and chemoresistance. In ovarian carcinoma cell lines, the specific knock-down of L1CAM reduces IL-1β expression and NF-κB activity.

CONCLUSIONS

L1CAM expression contributes to the invasive and metastatic phenotype of serous ovarian carcinoma. L1CAM expression and shedding in the tumor microenvironment could contribute to enhanced invasion and tumor progression through increased IL-1β production and NF-κB activation.

Combined treatment of L1CAM antibodies and cytostatic drugs improve the therapeutic response of pancreatic and ovarian carcinoma

The adhesion molecule L1CAM (CD171) accounts for enhanced motility, invasiveness and chemoresistance of tumor cells and represents a novel marker for various tumor entities including pancreatic and ovarian carcinoma. Recently, we showed that L1CAM inhibition increases the apoptotic response of tumor cells towards cytostatic drugs pointing to the potential of L1CAM to serve as a chemosensitizer in anti-cancer therapy. Thus, the present study evaluated the therapeutic potential of combined treatment with L1CAM antibodies and chemotherapeutic drugs in pancreatic and ovarian carcinoma model systems in vivo. Two L1CAM-specific antibodies (L1-14.10 and L1-9.3/2a) exhibiting high binding affinity to the L1CAM expressing pancreatic adenocarcinoma cell line Colo357 and the ovarian carcinoma cell line SKOV3ip were used for treatment. The combined therapy of SCID mice with either L1CAM antibody and gemcitabine and paclitaxel, respectively, reduced the growth of subcutaneously grown Colo357 or SKOV3ip tumors more efficiently than treatment with the cytostatic drug alone or in combination with control IgG. This was accompanied by an increased number of apoptotic tumor cells along with an elevated procaspase-8 expression. Furthermore, a lowered activation of NF-κB along with a reduced expression of VEGF and a diminished number of CD31-positive blood vessels were observed in tumors after combined therapy compared to control treatments, while the infiltration of F4/80-positive macrophages increased. Overall, these data provide new insights into the mechanism of the anti-cancer activity of L1CAM-blocking antibodies in vivo and support the suitability of L1CAM as a target for chemosensitization and of L1CAM-interfering antibodies as an appropriate tool to increase the therapeutic response of pancreatic and ovarian carcinoma.

Neurite outgrowth triggered by the cell adhesion molecule L1 requires activation and inactivation of the cytoskeletal protein cofilin

Neurite outgrowth, an essential process for constructing nervous system connectivity, requires molecular cues which promote neurite extension and guide growing neurites. The neural cell adhesion molecule L1 is one of the molecules involved in this process. Growth of neurites depends on actin remodeling, but actin-remodeling proteins which act downstream of L1 signaling are not known. In this study, we investigated whether the actin-remodeling protein cofilin, which can be activated by dephosphorylation, is involved in neurite outgrowth stimulated by L1. Upon stimulation with an L1 monoclonal antibody which specifically triggers L1-dependent neurite outgrowth, cofilin phosphorylation in cultured cerebellar granule neurons and isolated growth cones was reduced to 47 ± 13% or 58 ± 9% of IgG control levels, respectively. We therefore investigated whether cofilin phosphorylation plays a role in L1-stimulated neurite outgrowth. Inhibition of calcineurin, a phosphatase acting upstream of cofilin dephosphorylation, impaired L1-dependent neurite extension in cultures of cerebellar granule neurons and led to an increase in cofilin phosphorylation. Moreover, when peptide S3, a competitive inhibitor of cofilin phosphorylation, or peptide pS3, a competitive inhibitor of cofilin dephosphorylation, were transferred into cerebellar neurons in culture, L1-stimulated neurite outgrowth was reduced from 173 ± 15% to 103 ± 4% of poly-L-lysine control levels in the presence of either peptide. Our findings suggest that both activation of cofilin by dephosphorylation and inactivation of cofilin by phosphorylation are essential for L1-stimulated neurite outgrowth. These results are in accordance with a cofilin activity cycle recently proposed for invasive tumor cells and inflammatory cells, indicating that a similar regulatory mechanism might be involved in neurite outgrowth. As L1 is expressed by invasive tumor cells, cofilin might also be a downstream actor of L1 in metastasis.

Expression of l1 cell adhesion molecule and morphologic features at the invasive front of colorectal cancer

To obtain the correlation between morphologic features in the invasive fronts of colorectal cancer (CRC) and L1 cell adhesion molecule (L1CAM) expression, 275 CRCs were assessed with L1CAM immunostaining and 29 CRCs were examined for L1CAM messenger RNA (mRNA) expression. Based on immunostaining, the positive rate of L1CAM expression increased according to the grade of tumor budding (P = .0002) and solid cancer nests (SCNs; P = .0046). L1CAM mRNA levels at the invasive front of the tumor were higher than those at the center of the tumor (median, 3.7-fold). The gap of L1CAM mRNA level between the invasive front and the central area was 7.3-fold in tumors having SCN lesions, whereas it was 1.9-fold in tumors having non-SCN lesions (P = .0004). L1CAM expression was correlated with nodal involvement in protein and mRNA levels (P = .0007 and P = .036, respectively). Tumor regulation of L1CAM expression is associated with morphologic features at the invasive front in CRC.

Structural model and trans-interaction of the entire ectodomain of the olfactory cell adhesion molecule

The ectodomain of olfactory cell adhesion molecule (OCAM/NCAM2/RNCAM) consists of five immunoglobulin (Ig) domains (IgI-V), followed by two fibronectin-type 3 (Fn3) domains (Fn3I-II). A complete structural model of the entire ectodomain of human OCAM has been assembled from crystal structures of six recombinant proteins corresponding to different regions of the ectodomain. The model is the longest experimentally based composite structural model of an entire IgCAM ectodomain. It displays an essentially linear arrangement of IgI-V, followed by bends between IgV and Fn3I and between Fn3I and Fn3II. Proteins containing IgI-IgII domains formed stable homodimers in solution and in crystals. Dimerization could be disrupted in vitro by mutations in the dimer interface region. In conjunction with the bent ectodomain conformation, which can position IgI-V parallel with the cell surface, the IgI-IgII dimerization enables OCAM-mediated trans-interactions with an intercellular distance of about 20 nm, which is consistent with that observed in synapses.

Full-length L1CAM and not its Δ2Δ27 splice variant promotes metastasis through induction of gelatinase expression

Tumour-specific splicing is known to contribute to cancer progression. In the case of the L1 cell adhesion molecule (L1CAM), which is expressed in many human tumours and often linked to bad prognosis, alternative splicing results in a full-length form (FL-L1CAM) and a splice variant lacking exons 2 and 27 (SV-L1CAM). It has not been elucidated so far whether SV-L1CAM, classically considered as tumour-associated, or whether FL-L1CAM is the metastasis-promoting isoform. Here, we show that both variants were expressed in human ovarian carcinoma and that exposure of tumour cells to pro-metastatic factors led to an exclusive increase of FL-L1CAM expression. Selective overexpression of one isoform in different tumour cells revealed that only FL-L1CAM promoted experimental lung and/or liver metastasis in mice. In addition, metastasis formation upon up-regulation of FL-L1CAM correlated with increased invasive potential and elevated Matrix metalloproteinase (MMP)-2 and -9 expression and activity in vitro as well as enhanced gelatinolytic activity in vivo. In conclusion, we identified FL-L1CAM as the metastasis-promoting isoform, thereby exemplifying that high expression of a so-called tumour-associated variant, here SV-L1CAM, is not per se equivalent to a decisive role of this isoform in tumour progression.

L1 cell adhesion molecule as a novel independent poor prognostic factor in gallbladder carcinoma

Gallbladder carcinoma is a lethal malignancy and is hard to cure by current treatment. Thus, identification of molecular prognostic markers to predict gallbladder carcinoma as therapeutic targets is urgently needed. Recent studies have demonstrated that L1 cell adhesion molecule is associated with the prognosis of variable malignancy. Here, we investigated L1 cell adhesion molecule expression in gallbladder carcinoma and its prognostic significance. In this study, we examined L1 cell adhesion molecule expression in tumor specimens from 69 patients with gallbladder carcinoma by immunohistochemistry and analyzed the correlation between L1 cell adhesion molecule expression and clinicopathologic factors or survival. L1 cell adhesion molecule was not expressed in the normal epithelium of the gallbladder but in 63.8% of gallbladder carcinomas, remarkably at the invasive front of the tumors. In addition, L1 cell adhesion molecule expression was significantly associated with high histologic grade, advanced pathologic T stage and clinical stage, and positive venous/lymphatic invasion. Multivariate analyses showed that L1 cell adhesion molecule expression (hazard ratio, 3.503; P = .028) and clinical stage (hazard ratio, 3.091; P = .042) were independent risk factor for disease-free survival. L1 cell adhesion molecule expression in gallbladder carcinoma was significantly correlated with tumor progression and unfavorable clinicopathologic features. L1 cell adhesion molecule expression was an independent poor prognostic factor for disease-free survival in patients with gallbladder carcinoma. Taken together, our findings suggest that L1 cell adhesion molecule expression could be used as a novel prognostic factor for patient survival and might be a potential therapeutic target in gallbladder carcinomas.

Comparison of gene expression profiles in chromate transformed BEAS-2B cells

BACKGROUND

Hexavalent chromium [Cr(VI)] is a potent human carcinogen. Occupational exposure has been associated with increased risk of respiratory cancer. Multiple mechanisms have been shown to contribute to Cr(VI) induced carcinogenesis, including DNA damage, genomic instability, and epigenetic modulation, however, the molecular mechanism and downstream genes mediating chromium's carcinogenicity remain to be elucidated.

METHODS/RESULTS

We established chromate transformed cell lines by chronic exposure of normal human bronchial epithelial BEAS-2B cells to low doses of Cr(VI) followed by anchorage-independent growth. These transformed cell lines not only exhibited consistent morphological changes but also acquired altered and distinct gene expression patterns compared with normal BEAS-2B cells and control cell lines (untreated) that arose spontaneously in soft agar. Interestingly, the gene expression profiles of six Cr(VI) transformed cell lines were remarkably similar to each other yet differed significantly from that of either control cell lines or normal BEAS-2B cells. A total of 409 differentially expressed genes were identified in Cr(VI) transformed cells compared to control cells. Genes related to cell-to-cell junction were upregulated in all Cr(VI) transformed cells, while genes associated with the interaction between cells and their extracellular matrices were down-regulated. Additionally, expression of genes involved in cell proliferation and apoptosis were also changed.

CONCLUSION

This study is the first to report gene expression profiling of Cr(VI) transformed cells. The gene expression changes across individual chromate exposed clones were remarkably similar to each other but differed significantly from the gene expression found in anchorage-independent clones that arose spontaneously. Our analysis identified many novel gene expression changes that may contribute to chromate induced cell transformation, and collectively this type of information will provide a better understanding of the mechanism underlying chromate carcinogenicity.

Elevated invasive potential of glioblastoma stem cells

Glioblastomas (GBMs) are the most lethal and common types of primary brain tumors. The hallmark of GBMs is their highly infiltrative nature. The cellular and molecular mechanisms underlying the aggressive cancer invasion in GBMs are poorly understood. GBM displays remarkable cellular heterogeneity and hierarchy containing self-renewing glioblastoma stem cells (GSCs). Whether GSCs are more invasive than non-stem tumor cells and contribute to the invasive phenotype in GBMs has not been determined. Here we provide experimental evidence supporting that GSCs derived from GBM surgical specimens or xenografts display greater invasive potential in vitro and in vivo than matched non-stem tumor cells. Furthermore, we identified several invasion-associated proteins that were differentially expressed in GSCs relative to non-stem tumor cells. One of such proteins is L1CAM, a cell surface molecule shown to be critical to maintain GSC tumorigenic potential in our previous study. Immunohistochemical staining showed that L1CAM is highly expressed in a population of cancer cells in the invasive fronts of primary GBMs. Collectively, these data demonstrate the invasive nature of GSCs, suggesting that disrupting GSCs through a specific target such as L1CAM may reduce GBM cancer invasion and tumor recurrence.

L1CAM regulates DNA damage checkpoint response of glioblastoma stem cells through NBS1

Glioblastomas (GBMs) are highly lethal brain tumours with current therapies limited to palliation due to therapeutic resistance. We previously demonstrated that GBM stem cells (GSCs) display a preferential activation of DNA damage checkpoint and are relatively resistant to radiation. However, the molecular mechanisms underlying the preferential checkpoint response in GSCs remain undefined. Here, we show that L1CAM (CD171) regulates DNA damage checkpoint responses and radiosensitivity of GSCs through nuclear translocation of L1CAM intracellular domain (L1-ICD). Targeting L1CAM by RNA interference attenuated DNA damage checkpoint activation and repair, and sensitized GSCs to radiation. L1CAM regulates expression of NBS1, a critical component of the MRE11-RAD50-NBS1 (MRN) complex that activates ataxia telangiectasia mutated (ATM) kinase and early checkpoint response. Ectopic expression of NBS1 in GSCs rescued the decreased checkpoint activation and radioresistance caused by L1CAM knockdown, demonstrating that L1CAM signals through NBS1 to regulate DNA damage checkpoint responses. Mechanistically, nuclear translocation of L1-ICD mediates NBS1 upregulation via c-Myc. These data demonstrate that L1CAM augments DNA damage checkpoint activation and radioresistance of GSCs through L1-ICD-mediated NBS1 upregulation and the enhanced MRN-ATM-Chk2 signalling.

A migration signature and plasma biomarker panel for pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma is a disease of extremely poor prognosis for which there are no reliable markers of asymptomatic disease. To identify pancreatic cancer biomarkers, we focused on a genomic interval proximal to the most common fragile site in the human genome, chromosome 3p12, which undergoes smoking-related breakage, loss of heterozygosity, and homozygous deletion as an early event in many epithelial tumors, including pancreatic cancers. Using a functional genomic approach, we identified a seven-gene panel (TNC, TFPI, TGFBI, SEL-1L, L1CAM, WWTR1, and CDC42BPA) that was differentially expressed across three different expression platforms, including pancreatic tumor/normal samples. In addition, Ingenuity Pathways Analysis (IPA) and literature searches indicated that this seven-gene panel functions in one network associated with cellular movement/morphology/development, indicative of a "migration signature" of the 3p pathway. We tested whether two secreted proteins from this panel, tenascin C (TNC) and tissue factor pathway inhibitor (TFPI), could serve as plasma biomarkers. Plasma ELISA assays for TFPI/TNC resulted in a combined area under the curve (AUC) of 0.88 and, with addition of CA19-9, a combined AUC for the three-gene panel (TNC/TFPI/CA19-9), of 0.99 with 100% specificity at 90% sensitivity and 97.22% sensitivity at 90% specificity. Validation studies using TFPI only in a blinded sample set increased the performance of CA19-9 from an AUC of 0.84 to 0.94 with the two-gene panel. Results identify a novel 3p pathway-associated migration signature and plasma biomarker panel that has utility for discrimination of pancreatic cancer from normal controls and promise for clinical application.

Linking L1CAM-mediated signaling to NF-κB activation

The cell adhesion molecule L1 (L1CAM) was originally identified as a neural adhesion molecule essential for neurite outgrowth and axon guidance. Many studies have now shown that L1CAM is overexpressed in human carcinomas and associated with poor prognosis. So far, L1CAM-mediated cellular signaling has been largely attributed to an association with growth factor receptors, referred to as L1CAM-'assisted' signaling. New data demonstrate that L1CAM can signal via two additional mechanisms: 'forward' signaling via regulated intramembrane proteolysis and 'reverse' signaling via the activation of the transcription factor nuclear factor (NF)-κB. Taken together, these findings lead to a new understanding of L1CAM downstream signaling that is fundamental for the development of anti-L1CAM antibody-mediated therapeutics in human tumor cells.

Structural mechanism of the antigen recognition by the L1 cell adhesion molecule antibody A10-A3

The L1CAM antibody A10-A3 efficiently reduces tumor growth in a nude mouse model. Here, we describe the crystal structure of the Fab fragment of A10-A3 determined at 2.0 angstrom resolution. The A10-A3 antibody H3 loop reveals a characteristic arrangement of exposed aromatic residues that may play an important role in antigen binding. A structure model of the complex between L1CAM Ig1-4 and A10-A3 Fab indicates that the Fab binds to three small loops outside Ig1 and a residue between Ig1 and Ig2, consistent with an epitope mapping result. The data presented here should contribute to the design of high-affinity antibody for therapeutic purposes as well as to the understanding of neural cell remodeling and cancer progression mechanism mediated by L1CAM.

L1, β-catenin, and E-cadherin expression in patients with colorectal cancer: correlation with clinicopathologic features and its prognostic significance

OBJECTIVE

Currently, there are no clinically used/routine biomarkers that accurately predict whether colorectal cancer (CRC) patients will or will not respond to adjuvant chemotherapy. The aim of this study was to investigate L1, β-catenin, and E-cadherin expression in patients with CRC and their relationship to tumor progression, and to identify patients who will respond to chemotherapy.

METHODS

A total of 142 patients who underwent surgical treatment for CRC were chosen retrospectively. The samples from these patients were analyzed by immunohistochemistry. SPSS-14 program package was used for statistical calculation.

RESULTS

Expression of L1, β-catenin, and E-cadherin were found to be strongly associated with invasion and metastasis of CRC. Cox multivariate analysis results indicated that L1 expression and stage of Dukes could be considered as the independent prognostic factors for survival. Furthermore, our study found that the 5-year survival rate was the significantly associated with the expression of L1, β-catenin (normal and ectopic expression), and E-cadherin for Dukes' stage B (P < 0.01) patients. However, no such result was found for Dukes' stage A (P > 0.05) and C (P > 0.05) patients.

CONCLUSION

Our study provided reference for identifying patients who need adjuvant chemotherapy. L1, β-catenin, and E-cadherin could be considered as biomarkers to predict whether CRC patients will or will not respond to adjuvant chemotherapy.

Pheochromocytoma in rats with multiple endocrine neoplasia (MENX) shares gene expression patterns with human pheochromocytoma

Pheochromocytomas are rare neoplasias of neural crest origin arising from chromaffin cells of the adrenal medulla and sympathetic ganglia (extra-adrenal pheochromocytoma). Pheochromocytoma that develop in rats homozygous for a loss-of-function mutation in p27Kip1 (MENX syndrome) show a clear progression from hyperplasia to tumor, offering the possibility to gain insight into tumor pathobiology. We compared the gene-expression signatures of both adrenomedullary hyperplasia and pheochromocytoma with normal rat adrenal medulla. Hyperplasia and tumor show very similar transcriptome profiles, indicating early determination of the tumorigenic signature. Overrepresentation of developmentally regulated neural genes was a feature of the rat lesions. Quantitative RT-PCR validated the up-regulation of 11 genes, including some involved in neural development: Cdkn2a, Cdkn2c, Neurod1, Gal, Bmp7, and Phox2a. Overexpression of these genes precedes histological changes in affected adrenal glands. Their presence at early stages of tumorigenesis indicates they are not acquired during progression and may be a result of the lack of functional p27Kip1. Adrenal and extra-adrenal pheochromocytoma development clearly follows diverged molecular pathways in MENX rats. To correlate these findings to human pheochromocytoma, we studied nine genes overexpressed in the rat lesions in 46 sporadic and familial human pheochromocytomas. The expression of GAL, DGKH, BMP7, PHOX2A, L1CAM, TCTE1, EBF3, SOX4, and HASH1 was up-regulated, although with different frequencies. Immunohistochemical staining detected high L1CAM expression selectively in 27 human pheochromocytomas but not in 140 nonchromaffin neuroendocrine tumors. These studies reveal clues to the molecular pathways involved in rat and human pheochromocytoma and identify previously unexplored biomarkers for clinical use.

Soluble L1CAM promotes breast cancer cell adhesion and migration in vitro, but not invasion

Background

Neural recognition molecule L1CAM, which is a key protein involved in early nervous system development, is known to be abnormally expressed and shed in several types of cancers where it participates in metastasis and progression. The distinction of L1CAM presence in cancerous vs. normal tissues has suggested it to be a new target for cancer treatment. Our current study focused on the potential role of soluble L1CAM in breast cancer cell adhesion to extracellular matrix proteins, migration, and invasion.

Results

We found L1 expression levels were correlated with breast cancer stage of progression in established data sets of clinical samples, and also were high in more metastatic breast cancer cell lines MDA-MB-231 and MDA-MB-435, but low in less migratory MDA-MB-468 cells. Proteolysis of L1 into its soluble form (sL1) was detected in cell culture medium from all three above cell lines, and can be induced by PMA activation. Over-expression of the L1 ectodomain in MDA-MB-468 cells by using a lentiviral vector greatly increased the amount of sL1 released by those cells. Concomitantly, cell adhesion to extracellular matrix and cell transmigration ability were significantly promoted, while cell invasion ability through Matrigel™ remained unaffected. On the other hand, attenuating L1 expression in MDA-MB-231 cells by using a shRNA lentiviral vector resulted in reduced cell-matrix adhesion and transmigration. Similar effects were also shown by monoclonal antibody blocking of the L1 extracellular region. Moreover, sL1 in conditioned cell culture medium induced a directional migration of MDA-MB-468 cells, which could be neutralized by antibody treatment.

Conclusions

Our data provides new evidence for the function of L1CAM and its soluble form in promoting cancer cell adhesion to ECM and cell migration. Thus, L1CAM is validated further to be a potential early diagnostic marker in breast cancer progression and a target for breast cancer therapy.

L1CAM expression in endometrial carcinomas is regulated by usage of two different promoter regions

BACKGROUND

The L1 cell adhesion molecule (L1CAM) was originally identified as a neural adhesion molecule involved in axon guidance. In many human epithelial carcinomas L1CAM is overexpressed and thereby augments cell motility, invasion and metastasis formation. L1CAM positive carcinomas are associated with bad prognosis. Recent data point out that L1CAM is regulated in a fashion similar to epithelial-mesenchymal transition (EMT). Previous studies have implied the transcription factors Slug and/or β-catenin in L1CAM transcriptional regulation. However, the regulation of human L1CAM expression at the transcriptional level is not well understood.

RESULTS

To better understand the molecular basis of L1CAM transcriptional regulation, we carried out a detailed characterization of the human L1CAM promoter. We identified two transcription start sites, the first in front of a non-translated exon 0 (promoter 1) and the other next to the first protein-coding exon 1 (promoter 2). Both sites could be verified in endometrial carcinoma (EC) cell lines and appear to be used in a cell-type specific manner. The two identified promoter regions showed activity in luciferase reporter assays. Chromatin-IP analyses confirmed the in silico predicted E-boxes, binding sites for transcription factors Snail and Slug, as well as Lef-1 sites, which are related to β-catenin-mediated transcriptional regulation, in both promoters. Overexpression of β-catenin exclusively augmented activity of promoter 1 whereas Slug enhanced promoter 1 and 2 activity suggesting that both promoters can be active. Overexpression of β-catenin or Slug could upregulate L1CAM expression in a cell-type specific manner.

CONCLUSIONS

Our results, for the first time, provide evidence that the L1CAM gene has two functionally active promoter sites that are used in a cell-type specific manner. Slug and β-catenin are involved L1CAM transcriptional regulation. Nevertheless, Slug rather than β-catenin levels are correlated with L1CAM expression in EC cell lines. Our findings suggest that the L1CAM transcriptional regulation is more complex than anticipated and this study provides the basis for a better understanding of L1CAM regulation in non-neuronal/tumor cells.

Cancer stem cells in glioblastoma--molecular signaling and therapeutic targeting

Glioblastomas (GBMs) are highly lethal primary brain tumors. Despite current therapeutic advances in other solid cancers, the treatment of these malignant gliomas remains essentially palliative. GBMs are extremely resistant to conventional radiation and chemotherapies. We and others have demonstrated that a highly tumorigenic subpopulation of cancer cells called GBM stem cells (GSCs) promotes therapeutic resistance. We also found that GSCs stimulate tumor angiogenesis by expressing elevated levels of VEGF and contribute to tumor growth, which has been translated into a useful therapeutic strategy in the treatment of recurrent or progressive GBMs. Furthermore, stem cell-like cancer cells (cancer stem cells) have been shown to promote metastasis. Although GBMs rarely metastasize beyond the central nervous system, these highly infiltrative cancers often invade into normal brain tissues preventing surgical resection, and GSCs display an aggressive invasive phenotype. These studies suggest that targeting GSCs may effectively reduce tumor recurrence and significantly improve GBM treatment. Recent studies indicate that cancer stem cells share core signaling pathways with normal somatic or embryonic stem cells, but also display critical distinctions that provide important clues into useful therapeutic targets. In this review, we summarize the current understanding and advances in glioma stem cell research, and discuss potential targeting strategies for future development of anti-GSC therapies.

L1CAM malfunction in the nervous system and human carcinomas

Research over the last 25 years on the cell adhesion molecule L1 has revealed its pivotal role in nervous system function. Mutations of the human L1CAM gene have been shown to cause neurodevelopmental disorders such as X-linked hydrocephalus, spastic paraplegia and mental retardation. Impaired L1 function has been also implicated in the aetiology of fetal alcohol spectrum disorders, defective enteric nervous system development and malformations of the renal system. Importantly, aberrant expression of L1 has emerged as a critical factor in the development of human carcinomas, where it enhances cell proliferation, motility and chemoresistance. This discovery promoted collaborative work between tumour biologists and neurobiologists, which has led to a substantial expansion of the basic knowledge about L1 function and regulation. Here we provide an overview of the pathological conditions caused by L1 malfunction. We further discuss how the available data on gene regulation, molecular interactions and posttranslational processing of L1 may contribute to a better understanding of associated neurological and cancerous diseases.

L1 cell adhesion molecule is a novel independent poor prognostic factor of extrahepatic cholangiocarcinoma

PURPOSE

Cholangiocarcinomas (CC) are associated with poor survival, but diagnostic markers and therapeutic targets have not yet been elucidated. We previously found aberrant expression of L1 cell adhesion molecule in intrahepatic CC and a role for L1 in the progression of intrahepatic CC. Here, we analyzed L1 expression in extrahepatic CC (ECC) and evaluated its prognostic significance.

EXPERIMENTAL DESIGN

We examined L1 expression in tumors from 75 ECC patients by immunohistochemistry. We analyzed the correlations between L1 expression and clinicopathologic factors as well as patient survival.

RESULTS

L1 was not expressed in normal extrahepatic bile duct epithelium but was aberrantly expressed in 42.7% of ECC tumors. High expression of L1 was detected at the invasive front of tumors and was significantly associated with perineural invasion (P < 0.01). Univariate analysis indicated that various prognostic factors such as histologic grade 3, advanced pathologic T stage and clinical stage, perineural invasion, nodal metastasis, and high expression of L1 were risk factors predicting patient survival. Multivariate analyses done by Cox's proportional hazards model showed that high expression of L1 (hazard ratio, 2.171; 95% confidence interval, 1.162-4.055; P = 0.015) and nodal metastasis (hazard ratio, 2.088; 95% confidence interval, 1.159-3.764; P = 0.014) were independent risk factors for patient death.

CONCLUSIONS

L1 was highly expressed in 42.7% of ECC and its expression was significantly associated with perineural invasion. High expression of L1 and nodal metastasis were independent poor prognostic factors predicting overall survival in patients with ECC.

Stimulation of glioma cell motility by expression, proteolysis, and release of the L1 neural cell recognition molecule

Background

Malignant glioma cells are particularly motile and can travel diffusely through the brain parenchyma, apparently without following anatomical structures to guide their migration. The neural adhesion/recognition protein L1 (L1CAM; CD171) has been implicated in contributing to stimulation of motility and metastasis of several non-neural cancer types. We explored the expression and function of L1 protein as a stimulator of glioma cell motility using human high-grade glioma surgical specimens and established rat and human glioma cell lines.

Results

L1 protein expression was found in 17 out of 18 human high-grade glioma surgical specimens by western blotting. L1 mRNA was found to be present in human U-87/LacZ and rat C6 and 9L glioma cell lines. The glioma cell lines were negative for surface full length L1 by flow cytometry and high resolution immunocytochemistry of live cells. However, fixed and permeablized cells exhibited positive staining as numerous intracellular puncta. Western blots of cell line extracts revealed L1 proteolysis into a large soluble ectodomain (~180 kDa) and a smaller transmembrane proteolytic fragment (~32 kDa). Exosomal vesicles released by the glioma cell lines were purified and contained both full-length L1 and the proteolyzed transmembrane fragment. Glioma cell lines expressed L1-binding αvβ5 integrin cell surface receptors. Quantitative time-lapse analyses showed that motility was reduced significantly in glioma cell lines by 1) infection with an antisense-L1 retroviral vector and 2) L1 ectodomain-binding antibodies.

Conclusion

Our novel results support a model of autocrine/paracrine stimulation of cell motility in glioma cells by a cleaved L1 ectodomain and/or released exosomal vesicles containing L1. This mechanism could explain the diffuse migratory behavior of high-grade glioma cancer cells within the brain.