Aberrant promoter methylation of PCDH10 as a potential diagnostic and prognostic biomarker for patients with breast cancer

The role of Pcdh10 in neurological disease and cancer

BACKGROUND

Protocadherin 10 (PCDH 10), a member of the superfamily of protocadherins, is a Ca2+-dependent homophilic cell-cell adhesion molecule expressed on the surface of cell membranes. Protocadherin 10 plays a critical role in the central nervous system including in cell adhesion, formation and maintenance of neural circuits and synapses, regulation of actin assembly, cognitive function and tumor suppression. Additionally, Pcdh10 can serve as a non-invasive diagnostic and prognostic indicator for various cancers.

METHODS

This paper collects and reviews relevant literature in Pubmed.

CONCLUSION

This review describes the latest research understanding the role of Pcdh10 in neurological disease and human cancer, highlighting the importance of scrutinizing its properties for the development of targeted therapies and identifying a need for further research to explore Pcdh10 functions in other pathways, cell types and human pathologies.

E3 ubiquitin ligase RNF180 prevents excessive PCDH10 methylation to suppress the proliferation and metastasis of gastric cancer cells by promoting ubiquitination of DNMT1

BACKGROUND

Downregulation of certain tumor-suppressor genes (TSGs) by aberrant methylation of CpG islands in the promoter region contributes a great deal to the oncogenesis and progression of several cancers, including gastric cancer (GC). Protocadherin 10 (PCDH10) is a newly identified TSG in various cancers and is downregulated in GC; however, the specific mechanisms of PCDH10 in GC remain elusive. Here, we elucidated a novel epigenetic regulatory signaling pathway involving the E3 ubiquitin ligase RNF180 and DNA methyltransferase 1 (DNMT1), responsible for modulating PCDH10 expression by affecting its promoter methylation.

RESULTS

We revealed that PCDH10 was downregulated in GC cells and tissues, and low PCDH10 expression was correlated with lymph node metastasis and poor prognosis in patients with GC. Additionally, PCDH10 overexpression suppressed GC cell proliferation and metastasis. Mechanistically, DNMT1-mediated promoter hypermethylation resulted in decreased expression of PCDH10 in GC tissues and cells. Further analysis revealed that RNF180 can bind directly to DNMT1 and was involved in DNMT1 degradation via ubiquitination. Additionally, a positive correlation was found between RNF180 and PCDH10 expression and an inverse association between DNMT1 and PCDH10 expression showed considerable prognostic significance.

CONCLUSION

Our data showed that RNF180 overexpression upregulated PCDH10 expression via ubiquitin-dependent degradation of DNMT1, thus suppressing GC cell proliferation, indicating that the RNF180/DNMT1/PCDH10 axis could be a potential therapeutic target for GC treatment.

Innovative mouse models for the tumor suppressor activity of Protocadherin-10 isoforms

Background

Nonclustered mouse protocadherin genes (Pcdh) encode proteins with a typical single ectodomain and a cytoplasmic domain with conserved motifs completely different from those of classic cadherins. Alternative splice isoforms differ in the size of these cytoplasmic domains. In view of the compelling evidence for gene silencing of protocadherins in human tumors, we started investigations on Pcdh functions in mouse cancer models.

Methods

For Pcdh10, we generated two mouse lines: one with floxed exon 1, leading to complete Pcdh10 ablation upon Cre action, and one with floxed exons 2 and 3, leading to ablation of only the long isoforms of Pcdh10. In a mouse medulloblastoma model, we used GFAP-Cre action to locally ablate Pcdh10 in combination with Trp53 and Rb1 ablation. From auricular tumors, that also arose, we obtained tumor-derived cell lines, which were analyzed for malignancy in vitro and in vivo. By lentiviral transduction, we re-expressed Pcdh10 cDNAs. RNA-Seq analyses were performed on these cell families.

Results

Surprisingly, not only medulloblastomas were generated in our model but also tumors of tagged auricles (pinnae). For both tumor types, ablation of either all or only long isoforms of Pcdh10 aggravated the disease. We argued that the perichondrial stem cell compartment is at the origin of the pinnal tumors. Immunohistochemical analysis of these tumors revealed different subtypes. We obtained several pinnal-tumor derived (PTD) cell lines and analyzed these for anchorage-independent growth, invasion into collagen matrices, tumorigenicity in athymic mice. Re-expression of either the short or a long isoform of Pcdh10 in two PTD lines counteracted malignancy in all assays. RNA-Seq analyses of these two PTD lines and their respective Pcdh10-rescued cell lines allowed to identify many interesting differentially expressed genes, which were largely different in the two cell families.

Conclusions

A new mouse model was generated allowing for the first time to examine the remarkable tumor suppression activity of protocadherin-10 in vivo. Despite lacking several conserved motifs, the short isoform of Pcdh10 was fully active as tumor suppressor. Our model contributes to scrutinizing the complex molecular mechanisms of tumor initiation and progression upon PCDH10 silencing in many human cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09381-y.

Circular RNA PCDH10 regulates the tumorigenesis of pancreatic cancer through the miR-338-3p/hTERT axis

Protocadherin-10 (PCDH10) was previously identified as a pancreatic cancer (PC) suppressor by reducing telomerase activity through binding with human telomerase reverse transcriptase (hTERT). However, we did not observe any effects of PCDH10 on hTERT mRNA or protein expression. Our research found that the PCDH10 gene could be transcribed into linear mRNA or circular RNA, and FUS could bind to the introns flanking the circularized exons, inducing the PCDH10 linear mRNA to shift to circPCDH10 in PC cells. Knockdown of circPCDH10 significantly inhibited PC progression. Mechanistically, circPCDH10 acted as a sponge of miR-338-3p, which could negatively regulate hTERT expression in PC cells. The inhibitory effects of circPCDH10 knockdown on PC cells could be notably reversed by miR-338-3p inhibition and ectopic expression of hTERT. Overall, we propose that the increased FUS expression in PC cells made circPCDH10 the preferred product of the PCDH10 gene, and circPCDH10 might promote PC progression through upregulation of hTERT expression by targeting miR-338-3p.

Induction of fetal abnormalities and genotoxicity by molybdenum nanoparticles in pregnant female mice and fetuses

Increasing the uses of molybdenum (Mo) nanoparticles in a wide range of applications including food, industry, and medicine, resulted in increased human exposure and necessitated the study of their toxic effects. However, almost no studies are available on their genotoxic effects, especially on pregnant females and their fetuses. Therefore, this study was undertaken to estimate the possible induction of genotoxicity and fetal abnormalities, especially fetal malformations and skeletal abnormalities by Mo nanoparticle administration in mice. Oral administration of Mo nanoparticles resulted in significant decreases in the maternal body weight, the number and length of fetuses as well as skeletal abnormalities mainly less ossification and less chondrification. Administration of Mo nanoparticles also caused DNA damage induction which elevated the expression levels of p53, the vital gene in maintaining the genomic stability and cell differentiation in both maternal and fetus tissues. Similarly, the expression levels of E-Cad and N-Cad genes that control skeleton development have also been increased in the tissues of female mice administered Mo nanoparticles and their fetuses. Thus, we concluded that oral administration of Mo nanoparticles induced genotoxic effects and fetal abnormalities that necessitated further studies on the possible toxic effects of Mo nanoparticles.

Prognostic DNA methylation markers for hormone receptor breast cancer: a systematic review

BACKGROUND

In patients with hormone receptor-positive breast cancer, differentiating between patients with a low and a high risk of recurrence is an ongoing challenge. In current practice, prognostic clinical parameters are used for risk prediction. DNA methylation markers have been proven to be of additional prognostic value in several cancer types. Numerous prognostic DNA methylation markers for breast cancer have been published in the literature. However, to date, none of these markers are used in clinical practice.

METHODS

We conducted a systematic review of PubMed and EMBASE to assess the number and level of evidence of published DNA methylation markers for hormone receptor-positive breast cancer. To obtain an overview of the reporting quality of the included studies, all were scored according to the REMARK criteria that were established as reporting guidelines for prognostic biomarker studies.

RESULTS

A total of 74 studies were identified reporting on 87 different DNA methylation markers. Assessment of the REMARK criteria showed variation in reporting quality of the studies. Eighteen single markers and one marker panel were studied in multiple independent populations. Hypermethylation of the markers RASSF1, BRCA, PITX2, CDH1, RARB, PCDH10 and PGR, and the marker panel GSTP1, RASSF1 and RARB showed a statistically significant correlation with poor disease outcome that was confirmed in at least one other, independent study.

CONCLUSION

This systematic review provides an overview on published prognostic DNA methylation markers for hormone receptor-positive breast cancer and identifies eight markers that have been independently validated. Analysis of the reporting quality of included studies suggests that future research on this topic would benefit from standardised reporting guidelines.