Downregulation of TSLC1 and DAL-1 expression occurs frequently in breast cancer

Molecular interaction of metastasis suppressor genes and tumor microenvironment in breast cancer

Breast cancer (BC) is a leading cause of cancer-related deaths in women worldwide where the process of metastasis is a major contributor to the mortality associated with this disease. Metastasis suppressor genes are a group of genes that play a crucial role in preventing or inhibiting the spread of cancer cells. They suppress the metastasis process by inhibiting colonization and by inducing dormancy. These genes function by regulating various cellular processes in the tumor microenvironment (TME), such as cell adhesion, invasion, migration, and angiogenesis. Dysregulation of metastasis suppressor genes can lead to the acquisition of an invasive and metastatic phenotype and lead to poor prognostic outcomes. The components of the TME generally play a necessary in the metastasis progression of tumor cells. This review has identified and elaborated on the role of a few metastatic suppressors associated with the TME that have been shown to inhibit metastasis in BC by different mechanisms, such as blocking certain cell signaling molecules involved in cancer cell migration, invasion, enhancing immune surveillance of cancer cells, and promoting the formation of a protective extracellular matrix (ECM). Understanding the interaction of metastatic suppressor genes and the components of TME has important implications for the development of novel therapeutic strategies to target the metastatic cascade. Targeting these genes or their downstream signaling pathways offers a promising approach to inhibiting the spread of cancer cells and improves patient outcomes.

Combined Liquid Biopsy Methylation Analysis of CADM1 and MAL in Cervical Cancer Patients

Cervical cancer is the fourth most common cancer in women, which is associated in >95% with a high-risk human papillomavirus (HPV) infection. Methylation of specific genes has been closely associated with the progress of cervical high-grade dysplastic lesions to invasive carcinomas. Therefore, DNA methylation has been proposed as a triage for women infected with high-risk HPV. Methylation analyses of cervical cancer tissue have shown that cell adhesion molecule 1 (CADM1) and myelin and lymphocyte protein (MAL) methylation are present in over 90% of all cervical high-grade neoplasias and invasive cervical cancers. Here, we established a liquid biopsy-based assay to detect MAL and CADM1 methylation in cell free (cf)DNA of cervical cancer. Methylation of the target gene was validated on bisulfite converted smear-DNA from cervical dysplasia patients and afterward applied to cfDNA using quantitative real-time PCR. In 52 smears, a combined analysis of CADM1 and/or MAL (CADM1/MAL) showed methylation in 86.5% of the cases. In cfDNA samples of 24 cervical cancer patients, CADM1/MAL methylation was detected in 83.3% of the cases. CADM1/MAL methylation was detected already in 81.8% of stage I-II patients showing the high sensitivity of this liquid biopsy assay. In combination with a specificity of 95.5% towards healthy donors (HD) and an area under the curve (AUC) of 0.872 in the receiver operating characteristic (ROC) analysis, CADM1/MAL cfDNA methylation detection might represent a novel and promising liquid biopsy marker in cervical cancer.

Tumor Suppressor 4.1N/EPB41L1 is Epigenetic Silenced by Promoter Methylation and MiR-454-3p in NSCLC

Non–small-cell lung cancer (NSCLC) is divided into three major histological types, namely, lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC), and large-cell lung carcinoma (LCLC). We previously identified that 4.1N/EPB41L1 acts as a tumor suppressor and is reduced in NSCLC patients. In the current study, we explored the underlying epigenetic mechanisms of 4.1N/EPB41L1 reduction in NSCLC. The 4.1N/EPB41L1 gene promoter region was highly methylated in LUAD and LUSC patients. LUAD patients with higher methylation level in the 4.1N/EPB41L1 gene promoter (TSS1500, cg13399773 or TSS200, cg20993403) had a shorter overall survival time (Log-rank p = 0.02 HR = 1.509 or Log-rank p = 0.016 HR = 1.509), whereas LUSC patients with higher methylation level in the 4.1N/EPB41L1 gene promoter (TSS1500 cg13399773, TSS1500 cg07030373 or TSS200 cg20993403) had a longer overall survival time (Log-rank p = 0.045 HR = 0.5709, Log-rank p = 0.018 HR = 0.68 or Log-rank p = 0.014 HR = 0.639, respectively). High methylation of the 4.1N/EPB41L1 gene promoter appeared to be a relatively early event in LUAD and LUSC. DNA methyltransferase inhibitor 5-Aza-2′-deoxycytidine restored the 4.1N/EPB41L1 expression at both the mRNA and protein levels. MiR-454-3p was abnormally highly expressed in NSCLC and directly targeted 4.1N/EPB41L1 mRNA. MiR-454-3p expression was significantly correlated with 4.1N/EPB41L1 expression in NSCLC patients (r = −0.63, p < 0.0001). Therefore, we concluded that promoter hypermethylation of the 4.1N/EPB41L1 gene and abnormally high expressed miR-454-3p work at different regulation levels but in concert to restrict 4.1N/EPB41L1 expression in NSCLC. Taken together, this work contributes to elucidate the underlying epigenetic disruptions of 4.1N/EPB41L1 deficiency in NSCLC.

Pivotal roles of protein 4.1B/DAL‑1, a FERM‑domain containing protein, in tumor progression (Review)

Protein 4.1B/DAL‑1, encoded by erythrocyte membrane protein band 4.1‑like 3 (EPB41L3), belongs to the protein 4.1 superfamily, a group of proteins that share a conserved four.one‑ezrin‑radixin‑moesin (FERM) domain. Protein 4.1B/DAL‑1 serves a crucial role in cytoskeletal organization and a number of processes through multiple interactions with membrane proteins via its FERM, spectrin‑actin‑binding and C‑terminal domains. A number of studies have indicated that a loss of EPB41L3 expression is commonly observed in lung cancer, breast cancer, esophageal squamous cell carcinoma and meningiomas. DNA methylation and a loss of heterozygosity have been reported to contribute to the downregulation of EPB41L3. To date, the biological functions of protein 4.1B/DAL‑1 in carcinogenesis remain unknown. The present review summarizes the current understanding of the role of protein 4.1B/DAL‑1 in cancer and highlights its potential as a cancer diagnostic and prognostic biomarker in cancer therapeutics.

Asymmetrical methyltransferase PRMT3 regulates human mesenchymal stem cell osteogenesis via miR-3648

Histone arginine methylation, which is catalyzed by protein arginine methyltransferases (PRMTs), plays a key regulatory role in various biological processes. Several PRMTs are involved in skeletal development; however, their role in the osteogenic differentiation of mesenchymal stem cells (MSCs) is not completely clear. In this study, we aimed to elucidate the function of PRMT3, a type-I PRMT that catalyzes the formation of ω-mono- or asymmetric dimethyl arginine, in MSCs osteogenesis. We found that PRMT3 promoted MSCs osteogenic commitment and bone remodeling. PRMT3 activated the expression of miR-3648 by enhancing histone H4 arginine 3 asymmetric dimethylation (H4R3me2a) levels at promoter region of the gene. Overexpression of miR-3648 rescued impaired osteogenesis in PRMT3-deficient cells. Moreover, administration of Prmt3 shRNA or a chemical inhibitor of PRMT3 (SGC707) caused an osteopenia phenotype in mice. These results indicate that PRMT3 is a potential therapeutic target for the treatment of bone regeneration and osteopenia disorders.

CaMKK2 in myeloid cells is a key regulator of the immune-suppressive microenvironment in breast cancer

Tumor-associated myeloid cells regulate tumor growth and metastasis, and their accumulation is a negative prognostic factor for breast cancer. Here we find calcium/calmodulin-dependent kinase kinase (CaMKK2) to be highly expressed within intratumoral myeloid cells in mouse models of breast cancer, and demonstrate that its inhibition within myeloid cells suppresses tumor growth by increasing intratumoral accumulation of effector CD8+ T cells and immune-stimulatory myeloid subsets. Tumor-associated macrophages (TAMs) isolated from Camkk2-/- mice expressed higher levels of chemokines involved in the recruitment of effector T cells compared to WT. Similarly, in vitro generated Camkk2-/- macrophages recruit more T cells, and have a reduced capability to suppress T cell proliferation, compared to WT. Treatment with CaMKK2 inhibitors blocks tumor growth in a CD8+ T cell-dependent manner, and facilitates a favorable reprogramming of the immune cell microenvironment. These data, credential CaMKK2 as a myeloid-selective checkpoint, the inhibition of which may have utility in the immunotherapy of breast cancer.

Promoter hypermethylation in ductal carcinoma in situ of the male breast

Ductal carcinoma in situ (DCIS) of the male breast is very rare and has hardly been studied molecularly. In males, we compared methylation status of 25 breast cancer-related genes in pure DCIS (n = 18) and invasive breast carcinoma (IBC) with adjacent DCIS (DCIS-AIC) (n = 44) using methylation-specific multiplex ligation-dependent probe amplification. Results were compared to female breast cancer (BC). There were no significant differences in methylation features between male pure DCIS, DCIS-AIC and IBC after correction for multiple comparisons. In paired analysis of IBC and adjacent DCIS, CADM1 showed a significantly higher absolute methylation percentage in DCIS (P = 0.002). In cluster analysis, two clusters stood out with respectively infrequent and frequent methylation (GATA5, KLLN, PAX6, PAX5, CDH13, MSH6 and WT1 were frequently methylated). Compared to female DCIS, methylation was in general much less common in male DCIS, especially for VHL, ESR1, CDKN2A, CD44, CHFR, BRCA2, RB1 and STK11. In contrast, THBS1 and GATA5 were more frequently methylated in male DCIS. In conclusion, there is frequent methylation of GATA5, KLLN, PAX6, PAX5, CDH13, MSH6 and WT1 in male DCIS. Since there was little change in the methylation status for the studied genes from pure male DCIS to DCIS-AIC and IBC, methylation of these seven genes is more likely to occur early in male breast carcinogenesis. Based on the current markers male DCIS seems to be an epigenetically more advanced precursor of male BC, although in comparison to its female counterpart it appears that fewer loci harbor methylation, pointing to differences between male and female breast carcinogenesis with regard to the studied loci.

Decreased expression levels of DAL-1 and TOB1 are associated with clinicopathological features and poor prognosis in gastric cancer

PURPOSE

We previously demonstrated that the functional inactivation of DAL-1 and TOB1 promotes an aggressive phenotype in gastric cancer cells, but the links between both genes and the survival of patients with gastric cancer are unknown. Here, we investigated the correlations of the expression levels of DAL-1 and TOB1 with the progression of gastric cancer.

METHODS

A total of 270 patients who underwent resectable gastrectomy were included. The expression of DAL-1 and TOB1 was detected by immunohistochemistry.

RESULTS

Low expression of DAL-1 in cancer tissue was significantly associated with tumor site (p < 0.05), histological grade (p < 0.01), depth of invasion (p < 0.05), lymph node metastasis status (p < 0.05), Lauren classification (p < 0.001), and clinical stage (p < 0.01). A lower level of TOB1 was observed in gastric cancer patients with diffuse type disease compared to patients with either intestinal or mixed type disease (p < 0.001). Additionally, Spearman's correlation analysis revealed that decreased expression of DAL-1 was positively correlated with low TOB1 expression (r=0.304, p < 0.001). The survival analysis showed that low levels of DAL-1 and TOB1 were significantly associated with poor survival of gastric cancer patients (p <0.001 and p < 0.05, respectively).

CONCLUSION

The downregulation of DAL-1 and TOB1 expression is associated with shorter survival of gastric cancer patients. Hence, DAL-1 and TOB1 may be considered potential novel markers for predicting the outcomes of patients with gastric cancer.

Protein 4.1B Suppresses Tumor Metastasis by Regulating Epithelial-mesenchymal Transition Progression in Melanoma Cells

Epithelial-mesenchymal transition (EMT), which involves the dramatic reorganization of the cytoskeleton, is a crucial initiating step in tumor invasion and metastasis. Protein 4.1B is a membrane-cytoskeleton cross-linker that plays an important role in tumor progression and metastasis; however, the functional roles of 4.1B in melanoma remain unclear. In this study, we aimed to investigate the effect and underlying mechanism of 4.1B on melanoma cells. Our results demonstrated that 4.1B expression was downregulated in murine B16 and B16-F10 melanoma cell lines. Ectopic 4.1B expression significantly inhibited the migration of melanoma cells and pulmonary metastasis. We further investigated the possible mechanism underlying the effect of 4.1B on EMT. The results showed that ectopic 4.1B expression altered the expression of representative EMT markers (E-cadherin, vimentin and N-cadherin), and inhibited the expression of three important transcription factors (Slug, Snail, and Twist) related to EMT in melanoma cells. Moreover, the expression of integrin α5, β3 and matrix metalloproteinase 9 (MMP-9), which is known to regulate cell adhesion, migration and invasion, were suppressed. In conclusion, our data indicate that 4.1B is an important regulator during EMT progression in melanoma cells, which may present a potential target for the prevention and treatment of melanoma.

Lost expression of cell adhesion molecule 1 is associated with bladder cancer progression and recurrence and its overexpression inhibited tumor cell malignant behaviors

Cell adhesion molecule 1 (CADM1) regulates cell-cell adhesion and an altered expression level is associated with tumorigenesis and progression. The present study assessed CADM1 expression level in 84 bladder tissues to investigate the association with clinicopathological parameters from bladder cancer patients and then investigated the effects of CADM1 overexpression on T24 bladder cancer cells in vitro. The results demonstrated that expression level of CADM1 protein was significantly reduced in bladder cancer tissues (0.26±0.14) compared with in normal bladder mucosa (0.69±0.092; P<0.01), and methylation of CADM1 promoter was responsible for silencing of CADM1 protein expression and significantly associated with tumor size, recurrence, pathology classification and clinical stage (P<0.05). Overexpression of CADM1 protein inhibited tumor cell proliferation, reduced tumor cell invasion capacity and induced tumor cell apoptosis in vitro. At the gene level, CADM1 expression level upregulated caspase-3 activity and expression of Bax and p27 protein and downregulated levels of B cell lymphoma-2, cyclinD1, cyclinE1 and cyclin dependent kinase 2 proteins. Furthermore, overexpression of CADM1 regulated the expression level of epithelial to mesenchymal transition markers, including increased expression level of E-cadherin and β-catenin, whereas it decreased the levels of Vimentin. The present study demonstrated that lost expression of CADM1 protein may exert an essential role in the development and progression of bladder cancer and suggested that CADM1 may be a novel molecular target for the control of this disease in clinical practice.

XIAP Regulation by MNK Links MAPK and NFκB Signaling to Determine an Aggressive Breast Cancer Phenotype

Hyperactivation of the NFκB pathway is a distinct feature of inflammatory breast cancer (IBC), a highly proliferative and lethal disease. Gene expression studies in IBC patient tissue have linked EGFR (EGFR/HER2)-mediated MAPK signaling to NFκB hyperactivity, but the mechanism(s) by which this occurs remain unclear. Here, we report that the X-linked inhibitor of apoptosis protein (XIAP) plays a central role in linking these two pathways. XIAP overexpression correlated with poor prognoses in breast cancer patients and was frequently observed in untreated IBC patient primary tumors. XIAP drove constitutive NFκB transcriptional activity, which mediated ALDH positivity (a marker of stem-like cells), in vivo tumor growth, and an IBC expression signature in patient-derived IBC cells. Using pathway inhibitors and mathematical models, we defined a new role for the MAPK interacting (Ser/Thr)-kinase (MNK) in enhancing XIAP expression and downstream NFκB signaling. Furthermore, targeted XIAP knockdown and treatment with a MNK inhibitor decreased tumor cell migration in a dorsal skin fold window chamber murine model that allowed for intravital imaging of local tumor growth and migration. Together, our results indicate a novel role for XIAP in the molecular cross-talk between MAPK and NFκB pathways in aggressive tumor growth, which has the potential to be therapeutically exploited.Significance: Signaling by the MNK kinase is essential in inflammatory breast cancer, and it can be targeted to inhibit XIAP-NFκB signaling and the aggressive phenotype of this malignancy. Cancer Res; 78(7); 1726-38. ©2018 AACR.

Methylation of HPV and a tumor suppressor gene reveals anal cancer and precursor lesions

We studied DNA methylation patterns of human papillomavirus (HPV) and tumor suppressor gene EPB41L3 in 148 anal and perianal biopsies to determine whether high levels of methylation would be associated with anal intraepithelial neoplasia (AIN). The most prevalent HPV type was HPV16, detected in 54% of the 30 benign biopsies, 33% of the 43 low-grade AIN (lgAIN), 82% of the 59 high grade AIN (hgAIN) and 4 of the 5 anal cancers. A methylation score was developed (0.561*HPV16me+0.439*EPB41L3) which had increasing values with severity of disease: the mean was 8.1% in benign, 13.2% in lgAIN, 22.3% in hgAIN and 49.3% in cancers (p < 0.0001). The methylation score as a triage classifier at a cut-off of 8.8 gave a sensitivity of 90.6% (95% CI: 82.8, 96.9), specificity of 50.7% (95% CI: 39.7, 61.6) and area under the curve of 0.82 (95% CI: 0.75-0.89) for separating hgAIN and cancer from benign and lgAIN biopsies. We conclude that methylation of HPV16 and EPB41L3 show highly significant association with increasing severity of AIN and cancer and may be useful as biomarkers in anal disease.

Inhibitors of Protein Methyltransferases and Demethylases

Post-translational modifications of histones by protein methyltransferases (PMTs) and histone demethylases (KDMs) play an important role in the regulation of gene expression and transcription and are implicated in cancer and many other diseases. Many of these enzymes also target various nonhistone proteins impacting numerous crucial biological pathways. Given their key biological functions and implications in human diseases, there has been a growing interest in assessing these enzymes as potential therapeutic targets. Consequently, discovering and developing inhibitors of these enzymes has become a very active and fast-growing research area over the past decade. In this review, we cover the discovery, characterization, and biological application of inhibitors of PMTs and KDMs with emphasis on key advancements in the field. We also discuss challenges, opportunities, and future directions in this emerging, exciting research field.

Receptor FGFRL1 acts as a tumor suppressor in nude mice when overexpressed in HEK 293 Tet-On cells

Fibroblast growth factor receptor-like 1 (FGFRL1) is a transmembrane receptor that interacts with heparin and FGF ligands. In contrast to the classical FGF receptors, FGFR1 to FGFR4, it does not appear to affect cell growth and proliferation. In the present study, an inducible gene expression system was utilized in combination with a xenograft tumor model to investigate the effects of FGFRL1 on cell adhesion and tumor formation. It was determined that recombinant FGFRL1 promotes the adhesion of HEK 293 Tet-On® cells in vitro. Moreover, when such cells are induced to express FGFRL1ΔC they aggregate into huge clusters. If injected into nude mice, the cells form large tumors. Notably, this tumor growth is completely inhibited when the expression of FGFRL1 is induced. The forced expression of FGFRL1 in the tumor tissue may restore contact inhibition, thereby preventing growth of the cells in nude mice. The results of the present study demonstrate that FGFRL1 acts as a tumor suppressor similar to numerous other cell adhesion proteins. It is therefore likely that FGFRL1 functions as a regular cell-cell adhesion protein.

Next-generation sequencing identifies major DNA methylation changes during progression of Ph+ chronic myeloid leukemia

Little is known about the impact of DNA methylation on the evolution/progression of Ph+ chronic myeloid leukemia (CML). We investigated the methylome of CML patients in chronic phase (CP-CML), accelerated phase (AP-CML) and blast crisis (BC-CML) as well as in controls by reduced representation bisulfite sequencing. Although only ~600 differentially methylated CpG sites were identified in samples obtained from CP-CML patients compared with controls, ~6500 differentially methylated CpG sites were found in samples from BC-CML patients. In the majority of affected CpG sites, methylation was increased. In CP-CML patients who progressed to AP-CML/BC-CML, we identified up to 897 genes that were methylated at the time of progression but not at the time of diagnosis. Using RNA-sequencing, we observed downregulated expression of many of these genes in BC-CML compared with CP-CML samples. Several of them are well-known tumor-suppressor genes or regulators of cell proliferation, and gene re-expression was observed by the use of epigenetic active drugs. Together, our results demonstrate that CpG site methylation clearly increases during CML progression and that it may provide a useful basis for revealing new targets of therapy in advanced CML.

Aberrant expression of the candidate tumor suppressor gene DAL-1 due to hypermethylation in gastric cancer

By allelotyping for loss of heterozygosity (LOH), we previously identified a deletion region that harbors the candidate tumor suppressor gene DAL-1 at 18p11.3 in sporadic gastric cancers (GCs). The expression and function of DAL-1 in GCs remained unclear. Here, we demonstrated that the absence of or notable decreases in the expression of DAL-1 mRNA and protein was highly correlated with CpG hypermethylation of the DAL-1 promoter in primary GC tissues and in GC cell lines. Furthermore, abnormal DAL-1 subcellular localization was also observed in GC cells. Exogenous DAL-1 effectively inhibited cancer cell proliferation, migration, invasion and epithelial to mesenchymal transition (EMT); exogenous DAL-1 also promoted apoptosis in GC AGS cells. When endogenous DAL-1 was knocked down in GC HGC-27 cells, the cells appeared highly aggressive. Taken together, these findings provide solid evidence that aberrant expression of DAL-1 by hypermethylation in the promoter region results in tumor suppressor gene behavior that plays important roles in the malignancy of GCs. Understanding the role of it played in the molecular pathogenesis of GC, DAL-1 might be a potential biomarker for molecular diagnosis and evaluation of the GC.

Loss of CADM1/TSLC1 Expression Is Associated with Poor Clinical Outcome in Patients with Esophageal Squamous Cell Carcinoma

Aims. We sought to determine the relationship between CADM1/TSLC1 expression and clinicopathological characteristics in patients with esophageal squamous cell carcinoma (ESCC) and the correlation with survival. Materials and Methods. Two hundred and ninety-three ESCC tissues and paired adjacent normal esophageal tissues were immunohistochemically assessed in this study. The association of CADM1/TSLC1 with clinicopathological parameters, as well as disease-free survival (DFS) and overall survival (OS), was determined based on the Kaplan-Meier method and Cox regression models. Results. CADM1/TSLC1 was detected in 236 (80.5%) tumor tissues and 19 (8.0%) paired adjacent normal esophageal tissues. Decreased CADM1/TSLC1 expression was correlated with more advanced histological grade. CADM1/TSLC1 negative tumors were more frequently observed in male cases than in female cases. DFS and OS in the CADM1/TSLC1 negative group were significantly shorter than those in the positive group, particularly in male patients with ESCC. Conclusion. Loss or reduction of CADM1/TSLC1 expression is associated with more advanced histological grade and predicts early recurrence and short survival duration. Thus, loss of CADM1/TSLC1 could be a prognostic factor that can be used to assess the risk of recurrence and survival.

Tumor Suppressor in Lung Cancer-1 Is a Prognostic Predictor for the Recurrence and Progression of Non-Muscle-Invasive Bladder Cancer

OBJECTIVE

To investigate the relationship between the expression of tumor suppressor in lung cancer-1 (TSLC1) and clinicopathological characteristics of patients with non-muscle-invasive bladder cancer (NMIBC) and evaluate the prognostic significance of TSLC1.

METHODS

TSLC1 expression in 241 specimens of NMIBC was examined by immunohistochemistry. The correlation between TSLC1 expression and clinicopathological characteristics was evaluated using the chi-square test. The prognostic significance of TSLC1 was analyzed by univariate, multivariate analysis and Kaplan-Meier survival curves.

RESULTS

The total negative rate of TSLC1 expression was 47.3% in NMIBC. Decreased expression of TSLC1 was correlated with a higher clinical stage, higher pathological grade, the number of tumors, lager tumor size, tumor recurrence and progression. TSLC1 expression was an independent risk factor for predicting tumor recurrence (p = 0.005) and progression (p < 0.001).

CONCLUSION

Decreased expression of TSLC1 is correlated with the malignancy of NMIBC tissues and low TSLC1 expression may serve as a predictor for bladder cancer recurrence and progression.

DAL-1/4.1B contributes to epithelial-mesenchymal transition via regulation of transforming growth factor-β in lung cancer cell lines

The present study aimed to investigate the effects of the tumor suppressor gene differentially expressed in adenocarcinoma of the lung 1 (DAL‑1)/4.1B on early‑stage adenocarcinoma of the lung. The role of DAL‑1/4.1B in the epithelial‑mesenchymal transition (EMT), which is implicated in cancer metastasis, was examined using DAL‑1 knockdown and overexpression, followed by polymerase chain reaction and western blot analysis of EMT markers, as well as cell counting and cell migration/invasion assays. The results showed that DAL‑1/4.1B has a role in transforming growth factor (TGF)‑β‑induced EMT in non‑small cell lung cancer cells. Silencing of DAL‑1/4.1B with inhibitory RNAs altered the expression of numerous EMT markers, including E‑cadherin and β‑catenin, whereas overexpression of DAL‑1/4.1B had the opposite effect. In addition, DAL‑1/4.1B expression was induced following TGF‑β treatment at the protein and mRNA level. DAL‑1/4.1B deficiency impaired TGF‑β‑induced EMT and increased cell migration and invasion. These results suggested that DAL‑1/4.1B contributed to the EMT and may be important for tumor metastasis in lung cancer. Together with the results of a previous study by our group, the present study suggested that DAL‑1/4.1B acts as a tumor suppressor in the early transformation process in lung cancer, while in later stages, it functions as an oncogene affecting the biological features of human lung carcinoma cells. The results of the present study provided evidence for the feasibility of utilizing DAL‑1/4.1B as a target for lung cancer gene therapy.

Prolonged re-expression of the hypermethylated gene EPB41L3 using artificial transcription factors and epigenetic drugs

Epigenetic silencing of tumor suppressor genes (TSGs) is considered a significant event in the progression of cancer. For example, EPB41L3, a potential biomarker in cervical cancer, is often silenced by cancer-specific promoter methylation. Artificial transcription factors (ATFs) are unique tools to re-express such silenced TSGs to functional levels; however, the induced effects are considered transient. Here, we aimed to improve the efficiency and sustainability of gene re-expression using engineered zinc fingers fused to VP64 (ZF-ATFs) or DNA methylation modifiers (ZF-Tet2 or ZF-TDG) and/or by co-treatment with epigenetic drugs [5-aza-2'-deoxycytidine or Trichostatin A (TSA)]. The EPB41L3-ZF effectively bound its methylated endogenous locus, as also confirmed by ChIP-seq. ZF-ATFs reactivated the epigenetically silenced target gene EPB41L3 (∼ 10-fold) in breast, ovarian, and cervical cancer cell lines. Prolonged high levels of EPB41L3 (∼ 150-fold) induction could be achieved by short-term co-treatment with epigenetic drugs. Interestingly, for otherwise ineffective ZF-Tet2 or ZF-TDG treatments, TSA facilitated re-expression of EPB41L3 up to twofold. ATF-mediated re-expression demonstrated a tumor suppressive role for EPB41L3 in cervical cancer cell lines. In conclusion, epigenetic reprogramming provides a novel way to improve sustainability of re-expression of epigenetically silenced promoters.

Methylation of viral and host genes and severity of cervical lesions associated with human papillomavirus type 16

Methylation of human papillomavirus (HPV) and host genes may predict cervical cancer risk. We examined the methylation status of selected sites in HPV16 and human genes in DNA extracted from exfoliated cervical cell samples of 244 women harboring HPV16-positive cancer or cervical intraepithelial neoplasia (CIN) or negative for intraepithelial lesions or malignancy (NILM). We quantified the methylation of CpG sites in the HPV16 L1 gene (CpG 6367 and 6389) and in the human genes EPB41L3 (CpG 438, 427, 425) and LMX1 (CpG 260, 262, 266, 274) following bisulfite treatment and pyrosequencing. Receiver operating characteristic (ROC) curves were used to analyze the diagnostic utility of methylation level for the different sites and for a joint predictor score. Methylation in all sites significantly increased with lesion severity (p < 0.0001). Area under the curve (AUC) was highest among the CIN2/3 vs. cancer ranging from 0.786 to 0.853 among the different sites. Site-specific methylation levels strongly discriminated CIN2/3 from NILM/CIN1 and cancer from CIN2/3 (range of odds ratios [OR]: 3.69-12.76, range of lower 95% confidence bounds: 1.03-4.01). When methylation levels were mutually adjusted for each other EPB41L3 was the only independent predictor of CIN2/3 vs. NILM/CIN1 contrasts (OR = 9.94, 95%CI: 2.46-40.27). High methylation levels of viral and host genes are common among precancerous and cancer lesions and can serve as independent risk biomarkers. Methylation of host genes LMX1 and EPB41L3 and of the viral HPV16 L1 sites has the potential to distinguish among precancerous lesions and to distinguish the latter from invasive disease.

Loss of CADM1 expression is associated with poor prognosis and brain metastasis in breast cancer patients

Breast cancer brain metastases (BCBM) are detected with increasing incidence. In order to detect potential genes involved in BCBM, we first screened for genes down-regulated by methylation in cell lines with site-specific metastatic ability. The expression of five genes, CADM1, SPARC, RECK, TNFAIP3 and CXCL14, which were also found down-regulated in gene expression profiling analyses of BCBM tissue samples, was verified by qRT-PCR in a larger patient cohort. CADM1 was chosen for further down-stream analyses. A higher incidence of CADM1 methylation, correlating with lower expression levels, was found in BCBM as compared to primary BC. Loss of CADM1 protein expression was detected most commonly among BCBM samples as well as among primary tumors with subsequent brain relapse. The prognostic role of CADM1 expression was finally verified in four large independent breast cancer cohorts (n=2136). Loss of CADM1 protein expression was associated with disease stage, lymph node status, and tumor size in primary BC. Furthermore, all analyses revealed a significant association between loss of CADM1 and shorter survival. In multivariate analyses, survival was significantly shorter among patients with CADM1-negative tumors. Loss of CADM1 expression is an independent prognostic factor especially associated with the development of brain metastases in breast cancer patients.

DAL-1 attenuates epithelial-to mesenchymal transition in lung cancer

BACKGROUND

Epithelial-to mesenchymal transition (EMT) involves in metastasis, causing loss of epithelial polarity. Metastasis is the major cause of carcinoma-induced death, but mechanisms are poorly understood. Here we identify differentially expressed in adenocarcinoma of the lung-1 (DAL-1), a protein belongs to the membrane-associated cytoskeleton protein 4.1 family, as an efficient suppressor of EMT in lung cancer.

METHODS

The relationship between DAL-1 and EMT markers were analyzed by using immunohistochemistry in the clinical lung cancer tissues. Quantitative real-time PCR and western blot were used to characterize the expression of the EMT indicator mRNAs and proteins in DAL-1 overexpressed or knockdown cells. DAL-1 combined proteins were assessed by co-immunoprecipitation.

RESULTS

DAL-1 levels were strongly reduced even lost in lymph node metastasis and advanced pathological stage of human lung carcinomas. Overexpression of DAL-1 altered the expression of numerous EMT markers, such as E-cadherin, β-catenin Vimentin and N-cadherin expression, meanwhile changed the morphological shape of lung cancer cells, and whereas silencing DAL-1 had an opposite effect. DAL-1 directly combined with E-cadherin promoter and regulated its expression that could be the reason for impairing EMT and decreasing cell migration and invasion. Strikingly, HSPA5 was found as DAL-1 direct binding protein.

CONCLUSIONS

These results suggest that tumor suppressor DAL-1 could also attenuate EMT and be important for tumor metastasis in the early transformation process in lung cancer.

Selective inhibitors of protein methyltransferases

Mounting evidence suggests that protein methyltransferases (PMTs), which catalyze methylation of histone and nonhistone proteins, play a crucial role in diverse biological processes and human diseases. In particular, PMTs have been recognized as major players in regulating gene expression and chromatin state. PMTs are divided into two categories: protein lysine methyltransferases (PKMTs) and protein arginine methyltransferases (PRMTs). There has been a steadily growing interest in these enzymes as potential therapeutic targets and therefore discovery of PMT inhibitors has also been pursued increasingly over the past decade. Here, we present a perspective on selective, small-molecule inhibitors of PMTs with an emphasis on their discovery, characterization, and applicability as chemical tools for deciphering the target PMTs' physiological functions and involvement in human diseases. We highlight the current state of PMT inhibitors and discuss future directions and opportunities for PMT inhibitor discovery.

Tumor suppressor role of protein 4.1B/DAL-1

Protein 4.1B/DAL-1 is a membrane skeletal protein that belongs to the protein 4.1 family. Protein 4.1B/DAL-1 is localized to sites of cell-cell contact and functions as an adapter protein, linking the plasma membrane to the cytoskeleton or associated cytoplasmic signaling effectors and facilitating their activities in various pathways. Protein 4.1B/DAL-1 is involved in various cytoskeleton-associated processes, such as cell motility and adhesion. Moreover, protein 4.1B/DAL-1 also plays a regulatory role in cell growth, differentiation, and the establishment of epithelial-like cell structures. Protein 4.1B/DAL-1 is normally expressed in multiple human tissues, but loss of its expression or prominent down-regulation of its expression is frequently observed in corresponding tumor tissues and tumor cell lines, suggesting that protein 4.1B/DAL-1 is involved in the molecular pathogenesis of these tumors and acts as a potential tumor suppressor. This review will focus on the structure of protein 4.1B/DAL-1, 4.1B/DAL-1-interacting molecules, 4.1B/DAL-1 inactivation and tumor progression, and anti-tumor activity of the 4.1B/DAL-1.

Identification of a DNA methylome profile of esophageal squamous cell carcinoma and potential plasma epigenetic biomarkers for early diagnosis

DNA methylation is a critical epigenetic mechanism involved in key cellular processes. Its deregulation has been linked to many human cancers including esophageal squamous cell carcinoma (ESCC). This study was designed to explore the whole methylation status of ESCC and to identify potential plasma biomarkers for early diagnosis. We used Infinium Methylation 450k array to analyze ESCC tissues (n = 4), paired normal surrounding tissues (n = 4) and normal mucosa from healthy individuals (n = 4), and combined these with gene expression data from the GEO database. One hundred and sixty eight genes had differentially methylated CpG sites in their promoter region and a gene expression pattern inverse to the direction of change in DNA methylation. These genes were involved in several cancer-related pathways. Three genes were validated in additional 42 ESCC tissues and paired normal surrounding tissues. The methylation frequency of EPB41L3, GPX3, and COL14A1 were higher in tumor tissues than in normal surrounding tissues (P<0.017). The higher methylation frequency of EPB41l3 was correlated with large tumor size (P = 0.044) and advanced pT tumor stage (P = 0.001). The higher methylation frequency of GPX3 and COL14A1 were correlated with advanced pN tumor stage (P = 0.001 and P<0.001). The methylation of EPB41L3, GPX3, and COL14A1 genes were only found in ESCC patients' plasma, but not in normal individuals upon testing 42 ESCC patients and 50 healthy individuals. Diagnostic sensitivity was increased when methylation of any of the 3 genes were counted (64.3% sensitivity and 100% specificity). These differentially methylated genes in plasma may be used as biomarkers for early diagnosis of ESCC.

27-Hydroxycholesterol links hypercholesterolemia and breast cancer pathophysiology

Hypercholesterolemia is a risk factor for estrogen receptor (ER)-positive breast cancers and is associated with a decreased response of tumors to endocrine therapies. Here, we show that 27-hydroxycholesterol (27HC), a primary metabolite of cholesterol and an ER and liver X receptor (LXR) ligand, increases ER-dependent growth and LXR-dependent metastasis in mouse models of breast cancer. The effects of cholesterol on tumor pathology required its conversion to 27HC by the cytochrome P450 oxidase CYP27A1 and were attenuated by treatment with CYP27A1 inhibitors. In human breast cancer specimens, CYP27A1 expression levels correlated with tumor grade. In high-grade tumors, both tumor cells and tumor-associated macrophages exhibited high expression levels of the enzyme. Thus, lowering circulating cholesterol levels or interfering with its conversion to 27HC may be a useful strategy to prevent and/or treat breast cancer.

Clinical significance of expression of TSLC1, DAL-1/4.1B and MPP3 in colorectal carcinoma

AIM: To investigate the clinicopathological significance of expression of tumor suppressor in lung cancer-1 (TSLC1), differentially expressed in adenocarcinoma of the lung/4.1B (DAL-1/4.1B) and membrane protein palmitoylated 3 (MPP3) proteins in colorectal carcinoma.

METHODS: Immunohistochemistry was used to detect the expression of TSLC1, DAL-1/4.1B and MPP3 in 76 colorectal carcinoma tissue samples and 22 normal colorectal mucosal tissue samples. The correlation between expression of TSLC1, DAL-1/4.1B and MPP3 and clinicopathologic features of colorectal carcinoma was analyzed.

RESULTS: Positive staining for TSLC1, DAL-1/4.1B and MPP3 was observed in the cytoplasm and/or membrane of epithelial cells in normal colorectal mucosal tissue. The positive rates of TSLC1, DAL-1/4.1B and MPP3 expression were significantly lower in colorectal carcinoma than in normal control tissue (32.89% vs 81.81%, 27.63% vs 63.64%, 26.32% vs 68.18%; all P < 0.05). The lower expression of TSLC1, DAL-1/4.1B and MPP3 in colorectal carcinoma showed a significant correlation with degree of differentiation, depth of infiltration, lymph node metastasis and Dukes' stage (all P < 0.05), but not with gender, age or tumor size.

CONCLUSION: Low expression of TSLC1, DAL-1/4.1B and MPP3 may be involved the in the development and metastasis of colorectal carcinoma.

RASSF2 hypermethylation is present and related to shorter survival in squamous cervical cancer

Ras association (RalGDS/AF-6) domain family member 2 (RASSF2) is a gene involved in the progression of several human cancers, including breast, colorectal and lung cancer. The aims of this study were to determine the hypermethylation of the gene in squamous cervical cancer and precursor lesions, along with that of RASSF1 and the recently described EPB41L3, and to analyze the potential prognostic role of these genes. Methylation-specific PCR and bisulfite sequencing were used to analyze the methylation status of RASSF2 and EPB41L3 gene in 60 squamous cervical cancer, 76 cervical intraepithelial neoplasias grade III, 16 grade II, 14 grade I and 13 cases of normal tissue adjacent to cervical intraepithelial neoplasia. RASSF2 expression was evaluated by immunohistochemistry and the re-expression of RASSF2 and EPB41L3 was analyzed by quantitative reverse-transcription PCR in HeLa, SiHa, C33A and A431 cell lines treated with 5-aza-2'-deoxycytidine and/or trichostatin. RASSF1 hypermethylation and human papillomavirus type were also analyzed in all the cases by methylation-specific PCR and reverse line blot, respectively. RASSF2 hypermethylation was predominant in squamous cervical cancer (60.9%) compared with cervical intraepithelial neoplasias (4.2%) and was associated with a lower level of RASSF2 expression and vascular invasion in squamous cervical cancer. EPB41L3 and RASSF1 hypermethylations were also more frequent in cancer than in precursor lesions. Patients with RASSF2 hypermethylation had shorter survival time, independent of tumor stage (hazard ratio: 6.0; 95% confidence interval: 1.5-24.5). Finally, the expressions of RASSF2 and EPB41L3 were restored in several cell lines treated with 5-aza-2'-deoxycytidine. Taken together, our results suggest that RASSF2 potentially functions as a new tumor-suppressor gene that is inactivated through hypermethylation in cervical cancer and is related to the bad prognosis of these patients.

Clinicopathological significance of CADM4 expression in invasive ductal carcinoma of the breast

AIMS

Cell adhesion molecule 4 (CADM4) is a novel tumour suppressor involved in cell adhesion. Loss or decreased expression of CADM4 has been associated with the development and progression of some cancers. The purpose of this study was to investigate the clinicopathological significance of CADM4 expression in breast cancer.

METHODS

We constructed tissue microarrays to evaluate the immunohistochemical expression of CADM4 in 256 cases of invasive ductal carcinoma (IDC) and 45 cases of ductal carcinoma in situ (DCIS).

RESULTS

CADM4 was expressed in 37 (82.2%) DCIS cases, and in 173 (67.6%) IDC cases. CADM4 expression was higher in DCIS than in IDC (p=0.049). Loss or decrease of CADM4 expression was significantly correlated with higher histological grade (p=0.020), absence of oestrogen receptors (p<0.001), absence of progesterone receptors (p=0.024), and overexpression of c-erbB-2 (p=0.018). In univariable and multivariable Cox regression analyses of all 256 IDC cases, CADM4 expression was not significantly associated with overall and disease-free survival. However, it showed a significant positive association with longer disease-free survival in 187 stages I and II IDC cases (p=0.039, log-rank test).

CONCLUSIONS

Loss or decrease of CADM4 expression seems to play an important role in breast cancer invasiveness, and it is associated with poorer biological parameters. CADM4 can be used as a novel marker predicting risk of recurrence and disease outcomes in stages I and II IDC.

Tumor suppressor in lung cancer-1 (TSLC1) mediated by dual-regulated oncolytic adenovirus exerts specific antitumor actions in a mouse model

AIM

The tumor suppressor in lung cancer-1 (TSLC1) is a candidate tumor suppressor of lung cancer, and frequently inactivated in primary non-small cell lung cancer (NSCLC). In this study, we investigated the effects of TSLC1 mediated by a dual-regulated oncolytic adenovirus on lung cancer, and the mechanisms underlying the antitumor actions.

METHODS

The recombinant virus Ad·sp-E1A(Δ24)-TSLC1 was constructed by inserting the TSLC1 gene into the dual-regulated Ad·sp-E1A(Δ24) vector, which contained the survivin promoter and a 24 bp deletion within E1A. The antitumor effects of Ad·sp-E1A(Δ24)-TSLC1 were evaluated in NCI-H460, A549, and H1299 lung cancer cell lines and the normal fibroblast cell line MRC-5, as well as in A549 xenograft model in nude mice. Cell viability was assessed using MTT assay. The expression of TSLC1 and activation of the caspase signaling pathway were detected by Western blot analyses. The tumor tissues from the xenograft models were examined using H&E staining, IHC, TUNEL, and TEM analyses.

RESULTS

Infection of A549 lung cancer cells with Ad·sp-E1A(Δ24)-TSLC1 induced high level expression of TSLC1. Furthermore, the Ad·sp-E1A(Δ24)-TSLC1 virus dose-dependently suppressed the viability of NCI-H460, A549, and H1299 lung cancer cells, and did not affect MRC-5 normal fibroblast cells. Infection of NCI-H460, A549, and H1299 lung cancer cells with Ad·sp-E1A(Δ24)-TSLC1 induced apoptosis, and increased activation of caspase-8, caspase-3 and PARP. In A549 xenograft model in nude mice, intratumoral injection of Ad·sp-E1A(Δ24)-TSLC1 significantly suppressed the tumor volume, and increased the survival rate (from less than 15% to 87.5% at d 60). Histological studies showed that injection of Ad·sp-E1A(Δ24)-TSLC1 caused tumor cell apoptosis and virus particle propagation in tumor tissues.

CONCLUSION

The oncolytic adenovirus Ad·sp-E1A(Δ24)-TSLC1 exhibits specific antitumor effects, and is a promising agent for the treatment of lung cancer.

Breed-predispositions to cancer in pedigree dogs

Cancer is a common problem in dogs and although all breeds of dog and crossbred dogs may be affected, it is notable that some breeds of pedigree dogs appear to be at increased risk of certain types of cancer suggesting underlying genetic predisposition to cancer susceptibility. Although the aetiology of most cancers is likely to be multifactorial, the limited genetic diversity seen in purebred dogs facilitates genetic linkage or association studies on relatively small populations as compared to humans, and by using newly developed resources, genome-wide association studies in dog breeds are proving to be a powerful tool for unravelling complex disorders. This paper will review the literature on canine breed susceptibility to histiocytic sarcoma, osteosarcoma, haemangiosarcoma, mast cell tumours, lymphoma, melanoma, and mammary tumours including the recent advances in knowledge through molecular genetic, cytogenetic, and genome wide association studies.

Protein arginine methyltransferases and cancer

There are nine protein arginine methyltransferases (PRMTs) encoded in mammalian genomes, the protein products of which catalyse three types of arginine methylation--monomethylation and two types of dimethylation. Protein arginine methylation is an abundant modification that has been implicated in signal transduction, gene transcription, DNA repair and mRNA splicing, among others. Studies have only recently linked this modification to carcinogenesis and metastasis. Sequencing studies have not generally found alterations to the PRMTs; however, overexpression of these enzymes is often associated with various cancers, which might make some of them viable targets for therapeutic strategies.

Effect of TSLC1 gene on growth and apoptosis in human esophageal carcinoma Eca109 cells

INTRODUCTION

To explore the effect of tumor suppressor in lung cancer 1 (TSLC1) on proliferation and apoptosis in esophageal cancer Eca109 cells.

MATERIAL AND METHODS

Eca109 cells were divided into three groups: TSLC1 transfected group (TTG), mock group (MG) and untransfected group (UTG). The TTG and MG were transfected transiently with the pIRES2-EGFP-TSLC1 eukaryotic expression vector and pIRES2-EGFP vector respectively. The UTG was a blank control. The TSLC1 expression in TTG was analyzed with the fluorogram and RT-PCR method. Cell proliferation was measured with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Cell cycle was measured by flow cytometry (FCM). Cell apoptosis was detected by Annexin-V/PI double staining FCM.

RESULTS

Green color was found in TTG and MG. The band of TSLC1 mRNA of TTG was located at about 1400 bp by RT-PCR and agarose gel electrophoresis assay. The TSLC1 inhibited cell proliferation significantly in MTT assay, and the cell proliferation was slower in TTG than MG and UTG. After TSLC1 transfection, cell numbers increased in G0/G1 phase and decreased in S phase. Forty-eight hours after transfection, the apoptosis rate and death rate of TTG were higher than MG and UTG. Thus TSLC1 induced Eca109 cells to apoptosis.

CONCLUSIONS

The TSLC1 gene had a potent effect on cell proliferation inhibition, G1/S cell cycle arrest and induction of cell apoptosis in Eca109 cells.

Cadm1 is a metastasis susceptibility gene that suppresses metastasis by modifying tumor interaction with the cell-mediated immunity

Metastasis is a complex process utilizing both tumor-cell-autonomous properties and host-derived factors, including cellular immunity. We have previously shown that germline polymorphisms can modify tumor cell metastatic capabilities through cell-autonomous mechanisms. However, how metastasis susceptibility genes interact with the tumor stroma is incompletely understood. Here, we employ a complex genetic screen to identify Cadm1 as a novel modifier of metastasis. We demonstrate that Cadm1 can specifically suppress metastasis without affecting primary tumor growth. Unexpectedly, Cadm1 did not alter tumor-cell-autonomous properties such as proliferation or invasion, but required the host's adaptive immune system to affect metastasis. The metastasis-suppressing effect of Cadm1 was lost in mice lacking T cell–mediated immunity, which was partially phenocopied by depleting CD8⁺ T cells in immune-competent mice. Our data show a novel function for Cadm1 in suppressing metastasis by sensitizing tumor cells to immune surveillance mechanisms, and this is the first report of a heritable metastasis susceptibility gene engaging tumor non-autonomous factors.

Metastasis, the dissemination and growth of tumor cells in organs distinct from which they originated, is the most common cause of cancer-related death. Accumulating evidence indicates that an individual's genetic background, the heritable complement of genetic variations that distinguish individuals, not only contributes to overall cancer risk, but also specifically influences metastatic potential. Using a mouse model of metastatic breast cancer and complex genetic analysis, we have identified Cadm1 as a metastasis susceptibility gene. Cadm1 was previously identified as a tumor suppressor in lung adenocarcinoma, and reductions in its expression have been associated with poor survival in numerous cancer types. In this manuscript, we use in vivo modeling to show that high expression of Cadm1 inhibits pulmonary metastasis, while knockdown of Cadm1 promotes the metastatic capability of tumor cells. We further show that the metastasis-suppressive effect of Cadm1 expression is lost in mice lacking T cell–mediated immunity and that this effect is partially mediated by CD8⁺ T-lymphocytes. Our data suggest that the inverse correlation between Cadm1 expression and disease-free survival in humans is a result of a metastasis-suppressive interaction of Cadm1 with the cell-mediated immunity.

Decorin protein core affects the global gene expression profile of the tumor microenvironment in a triple-negative orthotopic breast carcinoma xenograft model

Decorin, a member of the small leucine-rich proteoglycan gene family, exists and functions wholly within the tumor microenvironment to suppress tumorigenesis by directly targeting and antagonizing multiple receptor tyrosine kinases, such as the EGFR and Met. This leads to potent and sustained signal attenuation, growth arrest, and angiostasis. We thus sought to evaluate the tumoricidal benefits of systemic decorin on a triple-negative orthotopic breast carcinoma xenograft model. To this end, we employed a novel high-density mixed expression array capable of differentiating and simultaneously measuring gene signatures of both Mus musculus (stromal) and Homo sapiens (epithelial) tissue origins. We found that decorin protein core modulated the differential expression of 374 genes within the stromal compartment of the tumor xenograft. Further, our top gene ontology classes strongly suggests an unexpected and preferential role for decorin protein core to inhibit genes necessary for immunomodulatory responses while simultaneously inducing expression of those possessing cellular adhesion and tumor suppressive gene properties. Rigorous verification of the top scoring candidates led to the discovery of three genes heretofore unlinked to malignant breast cancer that were reproducibly found to be induced in several models of tumor stroma. Collectively, our data provide highly novel and unexpected stromal gene signatures as a direct function of systemic administration of decorin protein core and reveals a fundamental basis of action for decorin to modulate the tumor stroma as a biological mechanism for the ascribed anti-tumorigenic properties.

The membrane-cytoskeletal protein 4.1N is involved in the process of cell adhesion, migration and invasion of breast cancer cells

Protein 4.1N belongs to the protein 4.1 superfamily that links transmembrane proteins to the actin cytoskeleton. Recent evidence has shown that protein 4.1 is important in tumor suppression. However, the functions of 4.1N in the metastasis of breast cancer are largely unknown. In the present study, MCF-7, T-47D and MDA-MB-231 breast cancer cell lines with various metastatic abilities were employed. Protein 4.1N was found to be expressed in poorly metastatic MCF-7 and middle metastatic T-47D cell lines, and was predominantly associated with cell-cell junctions. However, no 4.1N expression was detected in the highly metastatic MDA-MB-231 cells. Moreover, re-expression of 4.1N in MDA-MB-231 cells inhibited cell adhesion, migration and invasion. The results suggest that protein 4.1N is a negative regulator of cell metastasis in breast cancer.

Tumor suppressor TSLC1 is implicated in cell proliferation, invasion and apoptosis in laryngeal squamous cell carcinoma by regulating Akt signaling pathway

Overwhelming evidence has demonstrated that TSLC1 (tumor suppressor in lung cancer 1), a novel tumor suppressor, is crucially implicated in various biological processes including progression, proliferation and apoptosis during tumorigenesis. However, the exact functions and molecular details of TSLC1 in laryngeal cancer remain ill-defined. Here, the expression of TSLC1 in laryngeal squamous cell carcinoma (LSCC) tissues and cells was detected, and the biological roles of TSLC1 in LSCC cells were investigated. The results showed that expressions of TSLC1 mRNA and protein were significantly reduced in LSCC tissues with low expression in 18 of 85 (21.18 %) and 16 of 85 (18.82 %), respectively. Additionally, statistical analysis revealed a significant correlation of TSLC1 expression with TNM staging and lymph node metastases (P < 0.05), but not related to age, gender and tumor differentiation (P > 0.05). Elevation of TSLC1 level inhibited cell proliferation, reduced cell invasion in vitro and induced cell apoptosis in Hep-2 cells, most importantly, TSLC1 upregulation decreased the level of pAkt, but not changed the level of total Akt in Hep-2 cells. Stepwise investigations demonstrated that overexpression of TSLC1 in Hep-2 cells increased caspase-3 activity and expressions of bax and p21 proteins but decreased the levels of bcl-2, MMP-2 and MMP-9 proteins. These data suggest that TSLC1 may exert essential roles in the progression and development of LSCC, and thus TSLC1 may be a potential molecular target for LSCC treatment.

Loss of expression of the differentially expressed in adenocarcinoma of the lung (DAL-1) protein is associated with metastasis of non-small cell lung carcinoma cells

The differentially expressed in adenocarcinoma of the lung-1 (DAL-1) protein is a member of the membrane-associated cytoskeleton protein 4.1 family. This protein was previously found to be downregulated or lost in more than half of primary non-small cell lung cancers (NSCLC). In this study, the relationship between DAL-1 expression and NSCLC metastasis was examined. DAL-1 mRNA and protein levels were measured in NSCLC cell lines and in tumor cells isolated from the pleural fluid of NSCLC patients clinically diagnosed with distant metastases to the bone or brain. The results revealed that DAL-1 expression was observed in two (GLC-82 and NCI-H460) out of seven metastatic NSCLC cell lines examined. DAL-1 expression was not observed in the cells isolated from the pleural fluid in nine out of ten patients. Overexpression of DAL-1 in A549 cells, a cell line lacking endogenous DAL-1, inhibited cell migration and invasion by approximately 38 and 48 %, respectively. In contrast, DAL-1 knockdown in NCI-H460 cells enhanced the migration and invasion potential of this cell line 4.6- and 3-fold, respectively. Furthermore, DAL-1 promoter methylation was observed in six of nine pleural fluid NSCLC cell isolates and in two cell lines (A549 and H1299), as evidenced by a lack of endogenous DAL-1. Demethylation in A549 cells successfully restored DAL-1 mRNA and protein expression levels, resulting in a parallel remarkable inhibition of migration and invasion. These results indicated that DAL-1 was pivotal in triggering NSCLC migration and invasion and that loss of DAL-1 expression was due to the epigenetic methylation.

A four-gene methylation marker panel as triage test in high-risk human papillomavirus positive patients

Cervical neoplasia-specific biomarkers, e.g. DNA methylation markers, with high sensitivity and specificity are urgently needed to improve current population-based screening on (pre)malignant cervical neoplasia. We aimed to identify new cervical neoplasia-specific DNA methylation markers and to design and validate a methylation marker panel for triage of high-risk human papillomavirus (hr-HPV) positive patients. First, high-throughput quantitative methylation-specific PCRs (QMSP) on a novel OpenArray™ platform, representing 424 primers of 213 cancer specific methylated genes, were performed on frozen tissue samples from 84 cervical cancer patients and 106 normal cervices. Second, the top 20 discriminating methylation markers were validated by LightCycler® MSP on frozen tissue from 27 cervical cancer patients and 20 normal cervices and ROCs and test characteristics were assessed. Three new methylation markers were identified (JAM3, EPB41L3 and TERT), which were subsequently combined with C13ORF18 in our four-gene methylation panel. In a third step, our methylation panel detected in cervical scrapings 94% (70/74) of cervical cancers, while in a fourth step 82% (32/39) cervical intraepithelial neoplasia grade 3 or higher (CIN3+) and 65% (44/68) CIN2+ were detected, with 21% positive cases for ≤CIN1 (16/75). Finally, hypothetical scenario analysis showed that primary hr-HPV testing combined with our four-gene methylation panel as a triage test resulted in a higher identification of CIN3 and cervical cancers and a higher percentage of correct referrals compared to hr-HPV testing in combination with conventional cytology. In conclusion, our four-gene methylation panel might provide an alternative triage test after primary hr-HPV testing.

Overexpression of tumor suppressor TSLC1 by a survivin-regulated oncolytic adenovirus significantly inhibits hepatocellular carcinoma growth

PURPOSE

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Oncolytic viruses represent a promising therapeutic agent or vehicle to human cancers due to their ability of selectively lysing cancer cells but not in normal cells. TSLC1, a novel tumor suppressor gene, was loss in many human cancers including HCC, not in normal cells. The current study is focused on the antitumor effect of TSLC1-armed survivin-regulated oncolytic adenovirus for HCC and to explore their molecular mechanism.

METHODS

The expression of tumor suppressor TSLC1 and survivin was detected by quantitative PCR. The recombinant virus Ad.SP-E1A-E1B((Δ55))-TSLC1 (brief name as SD55-TSLC1) was constructed by inserting TSLC1 gene into the dual-regulated oncolytic adenovirus vector Ad.SP-E1A-E1B((Δ55)). Then, we performed the antitumor experiments of SD55-TSLC1 in vitro and in nude mice xenografted with Huh7 liver cancer.

RESULTS

The expression of TSLC1 was lower in HCC cells than in normal cells, which implied TSLC1 is a tumor suppressor of liver cancer. Survivin expression is higher in detected HCC cells than in normal cells. The SD55-TSLC1 exhibited an excellent antitumor effect on HCC cell growth in vitro but does no or little damage to normal liver cells. Animal experiment further confirmed that SD55-TSLC1 achieved significant inhibition of Huh7 liver cancer xenografted growth. Furthermore, the mechanism of antitumor efficacy by SD55-TSLC1 was elucidated to be due to the activation of caspase apoptotic pathway including the inducement of caspase-3, caspase-8, and poly (ADP-ribose) polymerase cleavage. This is the first report of TSLC1 by oncolytic adenovirus with an excellent antitumor effect to liver cancer growth.

CONCLUSION

These data suggest that an oncolytic adenovirus expressing TSLC1 is effective and support that SD55-TSLC1 may be a potent antitumoral agent for future clinical trials of liver cancer.

Protein 4.1B contributes to the organization of peripheral myelinated axons

Neurons are characterized by extremely long axons. This exceptional cell shape is likely to depend on multiple factors including interactions between the cytoskeleton and membrane proteins. In many cell types, members of the protein 4.1 family play an important role in tethering the cortical actin-spectrin cytoskeleton to the plasma membrane. Protein 4.1B is localized in myelinated axons, enriched in paranodal and juxtaparanodal regions, and also all along the internodes, but not at nodes of Ranvier where are localized the voltage-dependent sodium channels responsible for action potential propagation. To shed light on the role of protein 4.1B in the general organization of myelinated peripheral axons, we studied 4.1B knockout mice. These mice displayed a mildly impaired gait and motility. Whereas nodes were unaffected, the distribution of Caspr/paranodin, which anchors 4.1B to the membrane, was disorganized in paranodal regions and its levels were decreased. In juxtaparanodes, the enrichment of Caspr2, which also interacts with 4.1B, and of the associated TAG-1 and Kv1.1, was absent in mutant mice, whereas their levels were unaltered. Ultrastructural abnormalities were observed both at paranodes and juxtaparanodes. Axon calibers were slightly diminished in phrenic nerves and preterminal motor axons were dysmorphic in skeletal muscle. βII spectrin enrichment was decreased along the axolemma. Electrophysiological recordings at 3 post-natal weeks showed the occurrence of spontaneous and evoked repetitive activity indicating neuronal hyperexcitability, without change in conduction velocity. Thus, our results show that in myelinated axons 4.1B contributes to the stabilization of membrane proteins at paranodes, to the clustering of juxtaparanodal proteins, and to the regulation of the internodal axon caliber.

Construction of eukaryotic expression vector of TSLC1 gene

INTRODUCTION

To construct a eukaryotic expression vector of the tumour suppressor in lung cancer 1 (TSLC1) gene, so as to explore the mechanisms of tumour suppression of the gene theoretically.

MATERIAL AND METHODS

The open reading frame (ORF) of TSLC1 gene was amplified with RT-PCR from normal human foreskin acrobystia, and cloned to pMD19-T simple vector (TA Clone method). The resultant plasmid was transformed into Escherichia coli JM109 for amplification. The TA Clone recombinant was digested by double restriction enzyme (Bgl II/EcoR I) and analysed with agarose gel electrophoresis. The positive one was sequenced. The inserted DNA fragment was recovered, and then it was mounted into the eukaryotic expression vector pIRES2-EGFP, transformed into E. coli JM109 for amplification. A positive recombinant plasmid named pIRES2-EGFP-TSLC1 was confirmed by Bgl II/EcoR I double-enzyme digestion analysis.

RESULTS

RT-PCR amplified the ORF of the TSLC1 gene. It was approximately 1400 base pairs. The obtained DNA was confirmed a high degree of homology with the sequence of TSLC1 cDNA sequence (AY358334) stored at GenBank.

CONCLUSIONS

Construction of a TSLC1 eukaryotic expression vector was successful, and it has established a solid foundation for further study.