Expression of C4.4A at the invasive front is a novel prognostic marker for disease recurrence of colorectal cancer

BH-index: A predictive system based on serum biomarkers and ensemble learning for early colorectal cancer diagnosis in mass screening

BACKGROUND AND OBJECTIVE

Colorectal cancer is one of the most common malignancies among the general population. Artificial Intelligence methodologies based on serum parameters are in continuous development to obtain less expensive tools for highly sensitive diagnoses. This study proposes a predictive system based on serum biomarkers and ensemble learning to predict colorectal cancer presence and the related TNM stage in patients.

METHODS

We have selected 17 significant plasmatic proteins, i.e., Carcinoembryonic Antigen, CA 19-9, CA 125, CA 50, CA 72-4, Tissue Polypeptide Antigen, C-Reactive Protein, Ceruloplasmin, Haptoglobin, Transferrin, Ferritin, α-1-Antitrypsin, α-2-Macroglobulin, α-1 Acid Glycoprotein, Complement C4, Complement C3, and Retinol Binding Protein, regarding 345 patients (248 affected by the neoplastic disease). The proposed system consists of two predictors, i.e., binary and staging; the former predicts the presence/absence of cancer, while the latter identifies the related TNM stage (I, II, III, or IV). The experiments were conducted by deploying and comparing Random Forest, XGBoost, Support Vector Machine, and Multilayer Perceptron with feature selection based on Gini Importance and with dimensionality reduction via PCA.

RESULTS

The results show that the system composed of XGBoost as binary and staging predictor reaches 91.30% accuracy, 90% sensitivity, and 93.33% specificity for the absence/presence outcome, while 66.66% accuracy for the staging response. With the expansion of the training set in favor of positive patients and majority voting, the system composed of the combination of Support Vector Machine, XGBoost, and Multilayer Perceptron as the binary predictor reaches 98.03% accuracy, 100% sensitivity, and 92.30% specificity, while the combination of Random Forest, XGBoost, and Multilayer Perceptron as staging predictor achieves 60% accuracy. The final system reaches, in terms of accuracy, 98.03%, and 66.66% for the binary and staging predictors, respectively. It was also found that the biomarkers which contribute most to the binary decision are Ceruloplasmin and α-2-Macroglobulin, while the least significant dimensions are CA 50 and α-1-Antitrypsin; instead, Carcinoembryonic Antigen and α-1 Acid Glycoprotein are the most significant to the staging decision.

CONCLUSIONS

The present study proves the effectiveness of deploying serum biomarkers as feature dimensions for early colorectal cancer diagnosis and of using majority voting for noise reduction in the prediction.

Crystal Structures of Human C4.4A Reveal the Unique Association of Ly6/uPAR/α-neurotoxin Domain

Ly6/uPAR/α-neurotoxin domain (LU-domain) is characterized by the presence of 4-5 disulfide bonds and three flexible loops that extend from a core stacked by several conversed disulfide bonds (thus also named three-fingered protein domain). This highly structurally stable protein domain is typically a protein-binder at extracellular space. Most LU proteins contain only single LU-domain as represented by Ly6 proteins in immunology and α-neurotoxins in snake venom. For Ly6 proteins, many are expressed in specific cell lineages and in differentiation stages, and are used as markers. In this study, we report the crystal structures of the two LU-domains of human C4.4A alone and its complex with a Fab fragment of a monoclonal anti-C4.4A antibody. Interestingly, both structures showed that C4.4A forms a very compact globule with two LU-domain packed face to face. This is in contrast to the flexible nature of most LU-domain-containing proteins in mammals. The Fab combining site of C4.4A involves both LU-domains, and appears to be the binding site for AGR2, a reported ligand of C4.4A. This work reports the first structure that contain two LU-domains and provides insights on how LU-domains fold into a compact protein and interacts with ligands.

Cell-surface marker discovery for lung cancer

Lung cancer is the leading cause of cancer deaths in the United States. Novel lung cancer targeted therapeutic and molecular imaging agents are needed to improve outcomes and enable personalized care. Since these agents typically cannot cross the plasma membrane while carrying cytotoxic payload or imaging contrast, discovery of cell-surface targets is a necessary initial step. Herein, we report the discovery and characterization of lung cancer cell-surface markers for use in development of targeted agents. To identify putative cell-surface markers, existing microarray gene expression data from patient specimens were analyzed to select markers with differential expression in lung cancer compared to normal lung. Greater than 200 putative cell-surface markers were identified as being overexpressed in lung cancers. Ten cell-surface markers (CA9, CA12, CXorf61, DSG3, FAT2, GPR87, KISS1R, LYPD3, SLC7A11 and TMPRSS4) were selected based on differential mRNA expression in lung tumors vs. non-neoplastic lung samples and other normal tissues, and other considerations involving known biology and targeting moieties. Protein expression was confirmed by immunohistochemistry (IHC) staining and scoring of patient tumor and normal tissue samples. As further validation, marker expression was determined in lung cancer cell lines using microarray data and Kaplan–Meier survival analyses were performed for each of the markers using patient clinical data. High expression for six of the markers (CA9, CA12, CXorf61, GPR87, LYPD3, and SLC7A11) was significantly associated with worse survival. These markers should be useful for the development of novel targeted imaging probes or therapeutics for use in personalized care of lung cancer patients.

Expression of C4.4A in an In Vitro Human Tissue-Engineered Skin Model

A multi-LU-domain-containing protein denoted C4.4A exhibits a tightly regulated membrane-associated expression in the suprabasal layers of stratified squamous epithelia such as skin and the esophagus, and the expression of C4.4A is dysregulated in various pathological conditions. However, the biological function of C4.4A remains unknown. To enable further studies, we evaluated the expression of C4.4A in monolayer cultures of normal human keratinocytes and in tissue-engineered skin substitutes (TESs) produced by the self-assembly approach, which allow the formation of a fully differentiated epidermis tissue. Results showed that, in monolayer, C4.4A was highly expressed in the centre of keratinocyte colonies at cell-cell contacts areas, while some cells located at the periphery presented little C4.4A expression. In TES, emergence of C4.4A expression coincided with the formation of the stratum spinosum. After the creation of a wound within the TES, C4.4A expression was observed in the suprabasal keratinocytes of the migrating epithelium, with the exception of the foremost leading keratinocytes, which were negative for C4.4A. Our results are consistent with previous data in mouse embryogenesis and wound healing. Based on these findings, we conclude that this human TES model provides an excellent surrogate for studies of C4.4A and Haldisin expressions in human stratified epithelia.

De novo synthesis of C4.4A in hepatocellular carcinoma promotes migration and invasion of tumor cells

C4.4A is a glycoprotein that is upregulated in several human malignancies, including colorectal, breast and renal cell carcinomas. Due to its highly restricted expression in healthy tissue, C4.4A was proposed as a potential diagnostic marker. Thus, the present study was designed to evaluate C4.4A expression and function in hepatocellular carcinoma (HCC) for the first time. Immunohistochemistry was performed to detect expression of C4.4A in human sections of healthy liver, primary HCC in the liver and metastatic HCC in the lung. To assess the contribution of C4.4A to HCC progression proliferation, apoptosis, migration and invasion assays were performed with C4.4A knockdown Huh7 and HepG2 cells. C4.4A is absent in healthy liver tissue. However, intense expression was seen in 59% of primary HCCs and strong expression in 80% of HCC lung metastases. C4.4A expression was also observed in human HCC cell lines, which strongly increased under hypoxic conditions. A C4.4A knock-down revealed that C4.4A is involved in both migration and invasion of HCC cells. Taken together, C4.4A expression in both primary and metastatic HCC suggests its potential value as a diagnostic marker for HCC. Due to its absence in healthy liver tissue, C4.4A might even serve as a possible therapeutic target, particularly for metastatic HCC.

Expression and crystallographic studies of the D1D2 domains of C4.4A, a homologous protein to the urokinase receptor

C4.4A is a glycosylphosphatidylinositol-anchored membrane protein comprised of two LU domains (Ly6/uPAR-like domains) and an extensively O-glycosylated C-terminal Ser/Thr/Pro-rich region. C4.4A is a novel biomarker for squamous epithelial differentiation. Its expression is dysregulated under various pathological conditions and it is a robust biomarker for poor prognosis in various malignant conditions such as pulmonary adenocarcinoma. To facilitate crystallization, the two LU domains were excised from intact C4.4A by limited proteolysis, purified and crystallized by the sitting-drop vapour-diffusion method. The crystals diffracted to 2.7 Å resolution and belonged to space group C2221, with unit-cell parameters a = 55.49, b = 119.63, c = 168.54 Å. The statistics indicated good quality of the data, which form a solid basis for the determination of the C4.4A structure.

Preclinical Antitumor Efficacy of BAY 1129980-a Novel Auristatin-Based Anti-C4.4A (LYPD3) Antibody-Drug Conjugate for the Treatment of Non-Small Cell Lung Cancer

C4.4A (LYPD3) has been identified as a cancer- and metastasis-associated internalizing cell surface protein that is expressed in non-small cell lung cancer (NSCLC), with particularly high prevalence in the squamous cell carcinoma (SCC) subtype. With the exception of skin keratinocytes and esophageal endothelial cells, C4.4A expression is scarce in normal tissues, presenting an opportunity to selectively treat cancers with a C4.4A-directed antibody-drug conjugate (ADC). We have generated BAY 1129980 (C4.4A-ADC), an ADC consisting of a fully human C4.4A-targeting mAb conjugated to a novel, highly potent derivative of the microtubule-disrupting cytotoxic drug auristatin via a noncleavable alkyl hydrazide linker. In vitro, C4.4A-ADC demonstrated potent antiproliferative efficacy in cell lines endogenously expressing C4.4A and inhibited proliferation of C4.4A-transfected A549 lung cancer cells showing selectivity compared with a nontargeted control ADC. In vivo, C4.4A-ADC was efficacious in human NSCLC cell line (NCI-H292 and NCI-H322) and patient-derived xenograft (PDX) models (Lu7064, Lu7126, Lu7433, and Lu7466). C4.4A expression level correlated with in vivo efficacy, the most responsive being the models with C4.4A expression in over 50% of the cells. In the NCI-H292 NSCLC model, C4.4A-ADC demonstrated equal or superior efficacy compared to cisplatin, paclitaxel, and vinorelbine. Furthermore, an additive antitumor efficacy in combination with cisplatin was observed. Finally, a repeated dosing with C4.4A-ADC was well tolerated without changing the sensitivity to the treatment. Taken together, C4.4A-ADC is a promising therapeutic candidate for the treatment of NSCLC and other cancers expressing C4.4A. A phase I study (NCT02134197) with the C4.4A-ADC BAY 1129980 is currently ongoing. Mol Cancer Ther; 16(5); 893-904. ©2017 AACR.

LY6/PLAUR domain containing 3 has a role in the maintenance of colorectal cancer stem-like cells

Colorectal carcinoma (CRC) is one of the most frequently diagnosed cancers and the leading cause of cancer-related death for both men and women. Recent studies have revealed that a small sub-population of cancer cells, termed cancer stem-like cells (CSCs)/cancer-initiating cells (CICs), are endowed with tumor-initiating ability, self-renewal ability and differentiation ability. CSCs/CICs are resistant to current therapies including chemotherapy and radiotherapy. Thus, CSCs/CICs are responsible for recurrence and metastasis, and eradication of CSCs/CICs is essential to cure cancer. In this study, we isolated CR-CSCs/CICs as sphere-cultured cells and found that a product derived from LY6/PLAUR domain containing 3 (LYPD3) is preferentially expressed in CSCs/CICs. Gene overexpression and gene knockdown experiments revealed that LYPD3 has a role in the maintenance of CR-CSCs/CICs. The findings provide a novel molecular insight into CR-CSCs/CICs.

C4.4A gene ablation is compatible with normal epidermal development and causes modest overt phenotypes

C4.4A is a modular glycolipid-anchored Ly6/uPAR/α-neurotoxin multidomain protein that exhibits a prominent membrane-associated expression in stratified squamous epithelia. C4.4A is also expressed in various solid cancer lesions, where high expression levels often are correlated to poor prognosis. Circumstantial evidence suggests a role for C4.4A in cell adhesion, migration, and invasion, but a well-defined biological function is currently unknown. In the present study, we have generated and characterized the first C4.4A-deficient mouse line to gain insight into the functional significance of C4.4A in normal physiology and cancer progression. The unchallenged C4.4A-deficient mice were viable, fertile, born in a normal Mendelian distribution and, surprisingly, displayed normal development of squamous epithelia. The C4.4A-deficient mice were, nonetheless, significantly lighter than littermate controls predominantly due to differences in fat mass. Congenital C4.4A deficiency delayed migration of keratinocytes enclosing incisional skin wounds in male mice. In chemically induced bladder carcinomas, C4.4A deficiency attenuated the incidence of invasive lesions despite having no effect on total tumour burden. This new C4.4A-deficient mouse line provides a useful platform for future studies on functional aspects of C4.4A in tumour cell invasion in vivo.

Expression of C4.4A is a potential independent prognostic factor for patients with gastric cancer

C4.4A, a metastasis-associated gene, encodes a glycolipid-anchored membrane protein which is overexpressed in several human malignancies. However, there are few data available on C4.4A expression and its relationship with progression in gastric cancer. Our study was designed to explore the expression of C4.4A in gastric cancer and to correlate it with clinical outcome. C4.4A expression was studied by quantitative real-time RT-PCR and immunohistochemistry for assessment of correlations with clinicopathological factors. C4.4A mRNA expression was significantly up-regulated in gastric cancer as compared with noncancerous tissue (p<0.05)., being observed in 107 (88.4%) of the 121 gastric cancer cases by immunohistochemistry. We found that the expression of C4.4A mRNA was correlated with size of the tumor, depth of invasion, lymph node metastasis, distant metastasis and TNM stage. Moreover, patients with overexpression of C4.4A has a significantly worse survival (p<0.05). Further multivariable analysis indicated that the expression of C4.4A was an independent prognostic indicator for gastric cancer (p<0.05). In conclusion, overexpression of C4.4A correlates with metastatic potential of gastric cancer and C4.4A could be a novel independent prognostic marker for predicting outcome.

Reporting in studies of protein biomarkers of prognosis in colorectal cancer in relation to the REMARK guidelines

PURPOSE

The REMARK guidelines give authors comprehensive and specific advice on the complete and transparent reporting of studies of prognostic tumor markers. The aim of this study was to use the REMARK guidelines to evaluate the quality of reporting in a sample of studies assessing tissue-based protein markers for survival after resection of colorectal cancer.

EXPERIMENTAL DESIGN

Eighty pertinent articles were scored according to their conformity to 26 items derived from the REMARK criteria.

RESULTS

Overall, on a scale of adequacy of reporting that potentially ranged from 26 to 78, the median for these studies was 60 (interquartile range 54-64) and several criteria were adequately covered in a large proportion of studies. However, others were either not dealt with or inadequately covered, including description of the study design (35%), definition of survival endpoints (48%), adjuvant therapy (54%), follow-up procedures and time (59%), neoadjuvant therapy (63%), inclusion/exclusion criteria (73%), multivariable modeling methods and results (74%), and discussion of study limitations (85%).

CONCLUSIONS AND CLINICAL RELEVANCE

Inadequacies in presentation militate against comparability among protein marker studies and undermine the generalizability of their findings. The quality of reporting could be improved if journal editors were to require authors to ensure that their work satisfied the REMARK criteria.

New Blocking Antibodies against Novel AGR2-C4.4A Pathway Reduce Growth and Metastasis of Pancreatic Tumors and Increase Survival in Mice

Anterior gradient 2 (AGR2) promotes cancer growth, metastasis, and resistance to therapy via unknown mechanisms. We investigated the effects of extracellular AGR2 signaling through the orphan glycosylphosphatidylinositol-linked receptor C4.4A in pancreatic ductal adenocarcinoma (PDAC). Proliferation, migration, invasion, and apoptosis were measured using colorimetric, Boyden chamber, and FACS analyses. We developed blocking mAbs against AGR2 and C4.4A and tested their effects, along with siRNAs, on cancer cell functions and on orthotopic tumors in nude mice. Extracellular AGR2 stimulated proliferation, migration, invasion, and chemoresistance of PDAC cell lines. AGR2 interacted with C4.4A in cell lysates and mixtures of recombinant proteins. Knockdown of C4.4A reduced migration and resistance to gemcitabine. PDAC tissues, but not adjacent healthy pancreatic tissues, expressed high levels of AGR2 and C4.4A. AGR2 signaling through C4.4A required laminins 1 or 5 and integrin β1. Administration of antibodies against AGR2 and C4.4A reduced growth and metastasis and caused regression of aggressive xenograft tumors, leading to increased survival of mice. These data support a model in which AGR2 binds and signals via C4.4A in an autocrine loop and promotes the growth of pancreas tumors in mice. Blocking mAbs against AGR2 and C4.4A may have therapeutic potential against PDAC.

Clinical significance of RacGAP1 expression at the invasive front of gastric cancer

BACKGROUND

Rac GTPase activating protein 1 (RacGAP1) plays a regulatory role in cell growth, transformation and metastasis. The aim of this study was to clarify the association between RacGAP1 expression and clinical outcome in patients with gastric cancer.

METHODS

A total of 232 gastric cancer patients in our institute who underwent surgery without preoperative treatments were enrolled in this study. We investigated RacGAP1 expression using immunohistochemistry (IHC) and evaluated IHC scores calculated by the percentage of positive cells and intensity and its expression at the invasive front. RACGAP1 expression was also assessed.

RESULTS

RacGAP1 expression was observed in the nuclei of gastric cancer cells. Evaluation by IHC score showed no significant correlations with clinicopathological variables except for histological differentiation. In transcriptional analyses, RACGAP1 expression was elevated in diffuse type gastric cancer than intestinal type without a significant difference. We observed significant correlations of RacGAP1 protein expression at the invasive front with older age, tumor size, lymph node metastasis, lymphatic invasion, vascular invasion and advanced stage. Patients with RacGAP1 protein expression at the invasive front had significantly poorer prognosis than those without it (P < 0.0001). In multivariate analysis, lymph node metastasis, distant metastasis and positive RacGAP1 expression at the invasive front were independent prognostic factors (lymph node metastasis: P = 0.0106; distant metastasis: P = 0.0012; RacGAP1: P = 0.0011).

CONCLUSIONS

RacGAP1 expression at the invasive front in gastric cancer was significantly correlated with factors reflecting tumor progression and poor prognosis. Our data suggest that RacGAP1 might play important roles in the progression of gastric cancer.

Expression of the Ly6/uPAR-domain proteins C4.4A and Haldisin in non-invasive and invasive skin lesions

C4.4A and Haldisin belong to the Ly6/uPAR/α-neurotoxin protein domain family. They exhibit highly regulated expression profiles in normal epidermis, where they are confined to early (C4.4A) and late (Haldisin) squamous differentiation. We have now explored if dysregulated expressions occur in non-invasive and invasive skin lesions. In non-invasive lesions, their expression signatures were largely maintained as defined by that of normal epidermis. The scenario was, however, markedly different in the progression towards invasive squamous cell carcinomas. In its non-invasive stage (carcinoma in situ), a pronounced attenuation of C4.4A expression was observed, but upon transition to malignant invasive squamous cell carcinomas, the invasive fronts regained high expression of C4.4A. A similar progression was observed for the early stages of benign infiltrating keratoacanthomas. Interestingly, this transition was accompanied by a shift in the predominant association of C4.4A expression with CK1/10 in the normal epidermis to CK5/14 in the invasive lesions. In contrast, Haldisin expression maintained its confinement to the most-differentiated cells and was hardly expressed in the invasive lesions. Because this altered expression of C4.4A was seen in the invasive front of benign (keratoacanthomas) and malignant (squamous cell carcinomas) neoplasms, we propose that this transition of expression is primarily related to the invasive process.

C4.4A as a biomarker in pulmonary adenocarcinoma and squamous cell carcinoma

The high prevalence and mortality of lung cancer, together with a poor 5-year survival of only approximately 15%, emphasize the need for prognostic and predictive factors to improve patient treatment. C4.4A, a member of the Ly6/uPAR family of membrane proteins, qualifies as such a potential informative biomarker in non-small cell lung cancer. Under normal physiological conditions, it is primarily expressed in suprabasal layers of stratified squamous epithelia. Consequently, it is absent from healthy bronchial and alveolar tissue, but nevertheless appears at early stages in the progression to invasive carcinomas of the lung, i.e., in bronchial hyperplasia/metaplasia and atypical adenomatous hyperplasia. In the stages leading to pulmonary squamous cell carcinoma, expression is sustained in dysplasia, carcinoma in situ and invasive carcinomas, and this pertains to the normal presence of C4.4A in squamous epithelium. In pulmonary adenocarcinomas, a fraction of cases is positive for C4.4A, which is surprising, given the origin of these carcinomas from mucin-producing and not squamous epithelium. Interestingly, this correlates with a highly compromised patient survival and a predominant solid tumor growth pattern. Circumstantial evidence suggests an inverse relationship between C4.4A and the tumor suppressor LKB1. This might provide a link to the prognostic impact of C4.4A in patients with adenocarcinomas of the lung and could potentially be exploited for predicting the efficacy of treatment targeting components of the LKB1 pathway.

The metastasis-associated molecule C4.4A promotes tissue invasion and anchorage independence by associating with the alpha6beta4 integrin

C4.4A is a metastasis-associated molecule that functions appear to rely on associated alph6beta4 integrin. To corroborate the impact of the C4.4A-alpha6beta4 integrin association on metastasis formation, C4.4A was knocked-down in a highly metastatic rat pancreatic adenocarcinoma (ASML, ASML-C4.4Akd). Metastasis formation by ASML-C4.4Akd cells after intrafootpad application was strongly retarded in draining nodes and lung colonization was rare. Furthermore, cisplatin treatment significantly prolonged the survival time only of ASML-C4.4Akd-bearing rats. ASML-C4.4Akd cells display reduced migratory activity and impaired matrix protein degradation due to inefficient MMP14 activation; loss of drug-resistance is due to mitigated PI3K/Akt pathway activation. These losses of function rely on the laminin receptor C4.4A recruiting activated alpha6beta4 integrin into rafts, where C4.4A cooperates with alpha6beta4 and via alpha6beta4 with MMP14. Within this raft-located complex, MMP14 provokes focalized matrix degradation and mostly alpha6beta4 integrin promotes BAD phosphorylation and upregulated Bcl2 and BclXl expression. Thus, metastasis-promoting activities of C4.4A are not genuine characteristics of C4.4A. Instead, the raft-located laminin receptor C4.4A recruits alpha6beta4 integrin and supports via the alpha6beta4 integrin MMP14 activation. Thereby C4.4A acts as a linker to facilitate several steps in the metastatic cascade. Taking the restricted C4.4A expression in non-transformed tissue, this knowledge should pave the way toward the use of C4.4A as a therapeutic target.

C4.4A highly expressed in HER2-positive human breast cancers may indicate a good prognosis

BACKGROUND

The aim of our study was to investigate the association of C4.4A expression in breast tumors with both patients' clinicopathological characteristics and outcomes in order to clarify the significance of C4.4A in breast cancer.

METHODS

Primary breast cancer patients (n = 125, stage I-III) who had undergone breast mastectomy or breast-conserving surgery at our hospital between 2005 and 2011 were recruited for this study. Tumor samples were obtained from surgical specimens and expression status of C4.4A, estrogen receptors, progesterone receptors, human epidermal growth factor receptor 2 (HER2) and Ki67 was analyzed immunohistochemically, while HER2 amplification was examined using fluorescence in situ hybridization.

RESULTS

Multivariate analysis showed that HER2 positivity was the only independent predictive factor for C4.4A expression (odds ratio 5.31, 95 % confidence interval 2.04-15.72; P < 0.001). Univariate prognostic analysis of the relationship between C4.4A and disease-free survival showed that survival of patients with C4.4A-positive tumors was longer than that of patients with C4.4A-negative tumors in the HER2-positive subset (P = 0.004) while there was no significant difference in patient outcome according to C4.4A status for total patients (median observation period 37 months, range 1-92 months; P = 0.223).

CONCLUSIONS

We established a positive relationship between C4.4A and HER2 status, suggesting that C4.4A expression may be a prognostic factor for HER2-positive breast cancer patients.

The urokinase receptor homolog Haldisin is a novel differentiation marker of stratum granulosum in squamous epithelia

Several members of the Ly-6/uPAR (LU)-protein domain family are differentially expressed in human squamous epithelia. In some cases, they even play important roles in maintaining skin homeostasis, as exemplified by the secreted single domain member, SLURP-1, the deficiency of which is associated with the development of palmoplantar hyperkeratosis in the congenital skin disorder Mal de Meleda. In the present study, we have characterized a new member of the LU-protein domain family, which we find to be predominantly expressed in the stratum granulosum of human skin, thus resembling the expression of SLURP-1. In accordance with its expression pattern, we denote this protein product, which is encoded by the LYPD5 gene, as Haldisin (human antigen with LU-domains expressed in skin). Two of the five human glycolipid-anchored membrane proteins with multiple LU-domains characterized so far are predominantly confined to squamous epithelia (i.e., C4.4A), to stratum spinosum, and Haldisin to stratum granulosum under normal homeostatic conditions. Whether Haldisin is a prognostic biomarker for certain epithelial malignancies, like C4.4A and SLURP-1, remains to be explored.

Concurrent expression of C4.4A and Tenascin-C in tumor cells relates to poor prognosis of esophageal squamous cell carcinoma

C4.4A is a glycolipid-anchored membrane protein expressed in several human malignancies. We recently found that C4.4A expression was associated with poor prognosis of esophageal squamous carcinoma cells (ESCCs), but the underlying mechanism is unknown. To uncover this, we performed PCR array analysis using the HCT116 cell line, a positive control for C4.4A expression and we found that Tenascin-C (TNC) among the many adhesion molecules and extracellular matrix proteins was the best candidate for C4.4A molecule induction. Based on in vitro studies using the TE8 esophageal cancer cells, we examined by immunohistochemistry TNC expression in 111 ESCCs. We found that the TNC-positive group (24.3%) had significantly poorer prognosis than the TNC-negative group in 5-year overall survival. We also found there was a significant correlation between TNC and C4.4A in ESCC tissues (P=0.007). Finally, we found that only the double-positive group for C4.4A and TNC had a significantly worse prognosis (P=0.005). Our data suggest that TNC expression in ESCC may in part explain why C4.4A is associated with a poor prognosis of ESCC since TNC can promote invasion and metastasis.

C4.4A expression is associated with a poor prognosis of esophageal squamous cell carcinoma

BACKGROUND

C4.4A is a glycolipid-anchored membrane protein expressed in several human malignancies. We examined clinical relevance of C4.4A expression in 111 esophageal squamous cell carcinoma (ESCC) tissue samples.

METHODS

Anti-human C4.4A antibody that recognizes the glycosylphosphatidyl inositol (GPI) anchor signaling sequence (C4.4A-GPI Ab) and anti-human C4.4A-119 polyclonal antibody (C4.4A-119 Ab) were used for immunohistochemistry and Western blot testing.

RESULTS

Both antibodies detected the C4.4A protein expression at the parabasal layer of normal epithelium of the esophagus. In tumor tissues, the C4.4A protein was detected in 66 (59.5 %) and 95 (85.6 %) of 111 ESCCs by the C4.4A-GPI Ab and the C4.4A-119 Ab, respectively. The C4.4A-GPI Ab mainly detected membranous C4.4A expression (83.3 %, 55 of 66 positive cases), while the C4.4A-119 Ab exclusively detected cytoplasmic C4.4A expression (100 %, 73 cytoplasm alone and 22 cytoplasm plus membrane in 95 positive cases). Western blot analysis indicated that normal epithelium expressed the band of C4.4A at 70 kDa, whereas the tumor tissues displayed the band at the lower molecular weight. Survival analysis indicated that the C4.4A-positive ESCCs had significantly worse 5-year overall survival than the C4.4A-negative ESCC samples (P = 0.021) when using the C4.4A-GPI Ab, but not when using the C4.4A-119 Ab. This difference was most evident with membranous expression of C4.4A (P = 0.005).

CONCLUSIONS

C4.4A expression was associated with a poor prognosis of ESCC when the GPI-related antibody was used. On the other hand, the C4.4A-119 Ab may be a useful diagnostic tool for ESCC because of its high detection rate.

C4.4A is associated with tumor budding and epithelial-mesenchymal transition of colorectal cancer

C4.4A is a glycolipid-anchored membrane protein expressed in several human malignancies. The aim of this study was to explore the association between C4.4A expression at the invasion front of colorectal cancer (CRC) and tumor budding, a putative hallmark of cell invasion of CRC. Advanced CRCs (T2-4, n = 126) had a budding count of 3.66 ± 5.66, which was significantly higher than that of T1 early CRCs (1.75 ± 2.78, n = 87). C4.4A-positive CRC specimens showed a larger budding cell number than C4.4A-negative CRC specimens in T1 CRCs, and especially advanced CRCs (9.45 ± 5.83 vs 1.60 ± 3.93). Furthermore, we found a correlation between the percentage of C4.4A-positive cases and budding count in advanced CRC. Multivariate analysis for patients' survival showed that C4.4A was superior to tumor budding as a prognostic factor. With siRNA treatment, C4.4A levels were associated with cell invasion, but not with proliferation, in HCT116 and DLD1 cell lines. An immunohistochemical study in a subset of CRCs showed no relationship between C4.4A and Ki-67 proliferation marker. In vitro assays using HCT116 indicated that C4.4A levels correlated well with epithelial-mesenchymal transition (EMT) with regard to cell morphology and alterations of EMT markers including E-cadherin, vimentin, and partially N-cadherin. We also found that C4.4A expression was significantly associated with loss of E-cadherin and gain of β-catenin in clinical CRC tissue samples. These findings suggest that a tight association between C4.4A and tumor budding may, in part, be due to C4.4A promoting EMT at the invasive front of CRC.