Identification and characterization of human PCDH10 gene promoter

Retracted Article: Overexpression of PCDH8 inhibits proliferation and invasion, and induces apoptosis in papillary thyroid cancer cells

Protocadherin8 (PCDH8), a member of the protocadherin (PCDH) family, is involved in the progression of several types of cancers. However, the expression and biological roles of PCDH8 in papillary thyroid carcinoma (PTC) remain largely unknown. Therefore, in the present study, we detected the expression of PCDH8 in human PTC tissues and cell lines, and evaluated its role in PTC cells. Our results demonstrated that PCDH8 was lowly expressed in human PTC tissues and cell lines. In addition, ectopic expression of PCDH8 efficiently inhibited the proliferation, migration and invasion of PTC cells, as well as prevented the epithelial-mesenchymal transition (EMT) phenotype in PTC cells. Furthermore, PCDH8 efficiently induced apoptosis and autophagy in PTC cells. Mechanistically, overexpression of PCDH8 significantly prevented the activation of the Wnt/β-catenin pathway in PTC cells. Taken together, these findings showed that overexpression of PCDH8 inhibits proliferation and migration/invasion, and induces apoptosis of PTC cells through the Wnt/β-catenin signaling pathway.

Protocadherin8 (PCDH8), a member of the protocadherin (PCDH) family, is involved in the progression of several types of cancers.

Epigenetic silencing of protocadherin 10 in colorectal cancer

Colorectal cancer (CRC) is one of the most common types of malignant tumor in the world and occurs through a multi-step process resulting from the accumulation of genetic and epigenetic alterations of the genome. Although the molecular mechanisms of the pathogenesis of CRC remain unclear, the inactivation of tumor suppressor genes (TSGs) through promoter methylation serves an important role. Aberrant methylation is a well-defined marker of CRC. At present, the epigenetic silencing of protocadherin 10 (PCDH10) has been identified as an important TSG with key roles in colorectal carcinogenesis, invasion and metastasis as a frequent and early event. Advances in gene methylation detection in tumor tissues and body fluids have led to the development of non-invasive screening methods for CRC. The present study aimed to review the epigenetic alteration of PCDH10 in CRC development, and the potential of PCDH10 to be a non-invasive biomarker for CRC.

Nuclear factor-κB is involved in the protocadherin-10-mediated pro-apoptotic effect in multiple myeloma

The gene encoding protocadherin-10 (PCDH10), a member of the cadherin superfamily, has been recently identified as a tumor suppressor gene (TSG). PCDH10 plays important roles in the apoptosis of tumor cells in some cancer types. However, the exact role of PCDH10 in multiple myeloma (MM) is largely unknown. Increasing evidence has suggested that the activation of nuclear factor-κB (NF-κB) is crucial for apoptosis in myeloma cells. In this study, we investigated the pro-apoptotic effect of PCDH10 on myeloma cells and whether this effect may involve inhibition of the NF-κB pathway. We report here, for the first time to the best of our knowledge, that PCDH10 markedly induces apoptosis of myeloma cells, accompanied by an increase in activated caspase-3 and poly-ADP‑ribose polymerase (PARP) levels, and inhibited expression of anti‑apoptotic proteins. We also demonstrate that PCDH10 inhibits the activation of NF-κB, by inhibiting the expression of the inhibitor of nuclear factor-κB (IκB) kinase subunits (IKKs) and the phosphorylation of IκBα. Moreover, the constitutive NF-κB DNA-binding activity and the expression of the NF-κB‑regulated proteins cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF) and intercellular adhesion molecule 1 (ICAM-1) were inhibited by PCDH10 in MM cells. These results suggest that PCDH10 induces myeloma cell apoptosis, probably by inhibiting the NF-κB pathway.

Assessing signatures of selection through variation in linkage disequilibrium between taurine and indicine cattle

BACKGROUND

Signatures of selection are regions in the genome that have been preferentially increased in frequency and fixed in a population because of their functional importance in specific processes. These regions can be detected because of their lower genetic variability and specific regional linkage disequilibrium (LD) patterns.

METHODS

By comparing the differences in regional LD variation between dairy and beef cattle types, and between indicine and taurine subspecies, we aim at finding signatures of selection for production and adaptation in cattle breeds. The VarLD method was applied to compare the LD variation in the autosomal genome between breeds, including Angus and Brown Swiss, representing taurine breeds, and Nelore and Gir, representing indicine breeds. Genomic regions containing the top 0.01 and 0.1 percentile of signals were characterized using the UMD3.1 Bos taurus genome assembly to identify genes in those regions and compared with previously reported selection signatures and regions with copy number variation.

RESULTS

For all comparisons, the top 0.01 and 0.1 percentile included 26 and 165 signals and 17 and 125 genes, respectively, including TECRL, BT.23182 or FPPS, CAST, MYOM1, UVRAG and DNAJA1.

CONCLUSIONS

The VarLD method is a powerful tool to identify differences in linkage disequilibrium between cattle populations and putative signatures of selection with potential adaptive and productive importance.

CMTM3 inhibits human testicular cancer cell growth through inducing cell-cycle arrest and apoptosis

Human CMTM3 has been proposed as a putative tumor suppressor gene. The loss of CMTM3 has been found in several carcinomas. However, the regulation of CMTM3 expression and its function in tumor progression remain largely unknown. Here, we investigated the regulation of CMTM3 expression, function and molecular mechanism in human testicular cancer cells. CMTM3 was frequently downregulated or silenced in testicular cancer cell lines and tumor tissues but highly expressed in normal testis tissues. The re-expression of CMTM3 significantly suppressed the colony formation, proliferation, and migration capacity of testicular cancer cells by inducing a G2 cell cycle arrest and apoptosis. Moreover, the re-expression of CMTM3 activated the transcription of p53, induced p53 accumulation, up-regulated the expression of p21, and increased the cleavage of caspase 9, 8, 3, and PARP. The downregulation of CMTM3 in clinical tumor tissues was associated with the methylation of a single CpG site located within the Sp1/Sp3-responsive region of the core promoter. These results indicate that CMTM3 can function as tumor suppressor through the induction of a G2 cell cycle arrest and apoptosis. CMTM3 is thus involved in testicular cancer pathogenesis, and it is frequently at least partially silenced by the methylation of a single, specific CpG site in tumor tissues.

Epigenetic alteration: new insights moving from tissue to plasma - the example of PCDH10 promoter methylation in colorectal cancer

Background:

Tumour-released DNA in blood represents a promising biomarker for cancer detection. Although epigenetic alterations such as aberrant promoter methylation represent an appealing perspective, the discordance existing between frequencies of alterations found in DNA extracted from tumour tissue and cell-free DNA (cfDNA) has challenged their practical clinical application. With the aim to explain this bias of agreement, we investigated whether protocadherin 10 (PCDH10) promoter methylation in tissue was associated with methylation pattern in matched cfDNA isolated from plasma of patients with colorectal cancer (CRC), and whether the strength of concordance may depend on levels of cfDNA, integrity index, as well as on different clinical–pathological features.

Methods:

A quantitative methylation-specific PCR was used to analyse a selected CpG site in the PCDH10 promoter of 67 tumour tissues, paired normal mucosae, and matched plasma samples. The cfDNA integrity index and cfDNA concentration were assessed using a real-time PCR assay.

Results:

The PCDH10 promoter methylation was detected in 63 out of 67 (94.0%) surgically resected colorectal tumours and in 42 out of 67 (62.7%) plasma samples. The median methylation rate in tumour tissues and plasma samples was 43.5% (6.3–97.8%) and 5.9% (0–80.9%), respectively. There was a significant correlation between PCDH10 methylation in cfDNA and tumour tissue in patients with early CRC (P<0.0001). The ratio between plasma and tissue methylation rate increases with increasing cfDNA integrity index in early-stage cancers (P=0.0299) and with absolute cfDNA concentration in advanced cancers (P=0.0234).

Conclusion:

Our findings provide new insight into biological aspects modulating the concordance between tissues and plasma methylation profiles.

Frequent epigenetic silencing of PCDH10 by methylation in human colorectal cancer

PURPOSE

Aberrant DNA methylation is common in cancer cells. Epigenetic alterations resulting in the loss of tumor suppression gene functions are frequently involved in tumor development and progression. Recently, methylation of PCDH10 was reported to be associated with multiple hematologic malignancies as well as some solid tumors. Whether the down-regulation of PCDH10 happens in CRC remains unknown.

METHODS

Methylation status of PCDH10 was evaluated by methylation-specific PCR analysis. The effects of PCDH10 re-expression were determined in growth, colony formation, cell cycle, and invasion assays.

RESULTS

In this study, we found that 100 % (8 of 8) of colorectal cancer cell lines were silenced for PCDH10, but not normal colorectal epithelial cells. Demethylation treatment confirmed that the reduced expression is associated closely with promoter methylation. Hyper-methylation of PCDH10 was also detected in 85 % of primary colorectal tumors, but not in adjacent normal colorectal tissues.

CONCLUSIONS

Our results suggest that PCDH10 is an important tumor suppression gene with key roles of suppressing cell proliferation, clonogenicity, and inhibiting cell invasion in the development of colorectal cancer. Thus, PCDH10 methylation may constitute a useful biomarker of colorectal cancer patients.

Downregulation of protocadherin-10 expression correlates with malignant behaviour and poor prognosis in human bladder cancer

OBJECTIVES

This study retrospectively evaluated the prognostic significance of downregulated protocadherin-10 (PCDH10) gene expression in bladder cancer.

METHODS

To evaluate the prognostic significance of downregulated PCDH10 protein levels, immunohistochemistry was used to assess the level of PCDH10 protein in surgically-resected formalin-fixed, paraffin wax-embedded transitional cell carcinoma specimens. Relationships between PCDH10 protein levels, clinicopathological characteristics and overall survival were also evaluated.

RESULTS

A total of 105 bladder transitional cell carcinoma specimens and 33 normal bladder epithelial samples were investigated using immunohistochemical staining. PCDH10 protein levels were downregulated in 63.8% (67/105) of bladder cancer specimens compared with control samples. Downregulated levels of PCDH10 were significantly associated with advanced stage, higher grade, larger tumour size, nonpapillary shape, tumour recurrence and decreased overall survival rates. Multivariate analysis indicated that downregulated PCDH10 levels were independently associated with decreased overall survival and had a relative risk of death of 4.571.

CONCLUSIONS

Downregulated PCDH10 levels correlated with malignant behaviour and poor overall survival in patients with bladder cancer. Downregulated PCDH10 levels might be useful as a prognostic biomarker for bladder cancer.

A possible gene silencing mechanism: hypermethylation of the Keap1 promoter abrogates binding of the transcription factor Sp1 in lung cancer cells

Hypermethylation often leads to gene silencing; however, the mechanism responsible for the low expression resulting from hypermethylation of the tumor suppressor gene Kelch-like ECH-associating protein 1 (Keap1) in human lung cancer cell lines remains unclear. In this study, using promoter deletion and site mutagenesis assays, we determined that one transcription factor stimulating protein-1 (Sp1) regulatory element in the Keap1 promoter region was important for the transcription of Keap1 in A549 cells. We demonstrated that the transcription factor Sp1 can directly bind to this element in the normal bronchial epithelial BEAS-2B cell line but not in A549 cells, as assessed with chromatin immunoprecipitation (ChIP). EMSAs and supershift assays also showed that CpG island methylation could abrogate Sp1 binding to the Keap1 promoter. Moreover, Keap1 mRNA decreased by 50% after the knock-down of Sp1 with siRNA in BEAS-2B cells, whereas the over-expression of Sp1 led to a dramatic increase in Keap1 promoter activity. The treatment of A549 cells with 5-aza-2'-deoxycytidine restored the binding of Sp1 to the promoter and Keap1 expression. Our results indicate that Sp1 is essential for Keap1 expression and that promoter methylation blocks Sp1 binding in A549 cells. These results demonstrate that hypermethylation may act as an epigenetic gene silencing mechanism, i.e., the inhibition of Sp1 binding to the hypermethylated Keap1 promoter in lung cancer cells, which suggests new approaches to lung cancer treatment.

Silencing of PCDH10 in hepatocellular carcinoma via de novo DNA methylation independent of HBV infection or HBX expression

PCDH10 is a key tumor suppressive gene for nasopharyngeal, esophageal, and other carcinomas with frequent methylation. In this study, we investigated the potential epigenetic modification of the PCDH10 gene by hepatitis B virus × protein (HBx), a pivotal factor in the progression of HBV replication and potential carcinogenesis. PCDH10 expression was found to be down-regulated in 9/13 (69.2 %) of hepatocellular carcinoma (HCC) cell lines. Decreased PCDH10 expression was correlated with the methylation status of the PCDH10 promoter. Treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (Aza) was sufficient to restore PCDH10 mRNA expression by suppressing PCDH10 promoter methylation in HepG2 cells. Treatment with Trichostatin A alone had no significant effect on PCDH10 expression but enhanced the effect of Aza. PCDH10 methylation was further detected in 76 % (38 of 50) of HCC tissues compared with 40 % (20 of 50) of paired adjacent tissues, with no methylation detected in normal human liver tissues. There were significant correlations between methylation status of PCDH10 and tumor size, serum AFP levels, metastasis or TNM staging (P < 0.05). Moreover, PCDH10 promoter methylation status was not associated with HBV infection in our panel of 50 primary HCC tumors, and transfection with HBX could not alter the status of PCDH10 promoter methylation. Collectively, these observations suggested that the expression of PCDH10 was silenced in HCC via de novo DNA methylation independent of HBV infection or HBX expression, and PCDH10 might form a potentially useful therapeutic target for HCC.

Protocadherin-10 is involved in angiogenesis and methylation correlated with multiple myeloma

Protocadherin-10 (PCDH10) which is located at 4q28.3, is a member of the cadherin superfamily of cell adhesion molecules. PCDH10 is broadly expressed in normal adult, but nearly undetectable in multiple myeloma (MM) tissues and cell lines. Its promoter methylation was detected in virtually all the silenced or downregulated cell lines. The silencing of PCDH10 could be reversed by pharmacological demethylation, indicating a methylation-mediated mechanism. In the current study, we investigated 44 patients (23 females, 21 males), 77.27% (34/44) of whom presented high methylation of PCDH10. We found no associations between promoter hypermethylation and gender or age at the time of initial diagnosis. We also examined the role of PCDH10 as a mediator of MM cell proliferation, cell cycle progression, and its involvement in angiogenesis. Our results demonstrate that the PCDH10 gene is a target for epigenetic silencing in MM and provide a link between the dysregulation of angiogenesis and DNA methylation.

Epigenetic inactivation of PCDH10 in human prostate cancer cell lines

PCDH10 (protocadherin-10), a novel tumour suppressor gene, is down-regulated in several human cancers due to hypermethylation of promoter CGIs (CpG islands). Here, we investigated the expression of PCDH10 in different normal adult tissues and in a panel of prostate cancer cell lines. PCDH10 was widely expressed in normal tissues with higher levels in the prostate. The expression of PCDH10 was markedly reduced or silenced in prostate cancer cell lines compared with normal adult prostate tissue. Decreased PCDH10 expression was correlated with the methylation status of the PCDH10 promoter. Furthermore, the DNA demethylating agent 5'-azacytidin restored PCDH10 expression by suppressing PCDH10 promoter methylation in prostate cancer cell lines. Treatment with Trichostatin A alone had no significant effect on the expression of PCDH10 but enhanced the effect of 5'-azacytidin. In conclusion, we found that the decreased PCDH10 expression in prostate cancer cells was associated with the aberrant methylation of PCDH10 promoter CGI. Our results may contribute to the understanding of the role of PCDH10 inactivation in the progression of prostate cancers.