Methylation and expression analyses of Pallister-Killian syndrome reveal partial dosage compensation of tetrasomy 12p and hypomethylation of gene-poor regions on 12p

Four centrosome-related genes to predict the prognosis and drug sensitivity of patients with colon cancer

BACKGROUND

As the primary microtubule organizing center in animal cells, centrosome abnormalities are involved in human colon cancer.

AIM

To explore the role of centrosome-related genes (CRGs) in colon cancer.

METHODS

CRGs were collected from public databases. Consensus clustering analysis was performed to separate the Cancer Genome Atlas cohort. Univariate Cox and least absolute shrinkage selection operator regression analyses were performed to identify candidate prognostic CRGs and construct a centrosome-related signature (CRS) to score colon cancer patients. A nomogram was developed to evaluate the CRS risk in colon cancer patients. An integrated bioinformatics analysis was conducted to explore the correlation between the CRS and tumor immune microenvironment and response to immunotherapy, chemotherapy, and targeted therapy. Single-cell transcriptome analysis was conducted to examine the immune cell landscape of core prognostic genes.

RESULTS

A total of 726 CRGs were collected from public databases. A CRS was constructed, which consisted of the following four genes: TSC1, AXIN2, COPS7A, and MTUS1. Colon cancer patients with a high-risk signature had poor survival. Patients with a high-risk signature exhibited decreased levels of plasma cells and activated memory CD4+ T cells. Regarding treatment response, patients with a high-risk signature were resistant to immunotherapy, chemotherapy, and targeted therapy. COPS7A expression was relatively high in endothelial cells and fibroblasts. MTUS1 expression was high in endothelial cells, fibroblasts, and malignant cells.

CONCLUSION

We constructed a centrosome-related prognostic signature that can accurately predict the prognosis of colon cancer patients, contributing to the development of individualized treatment for colon cancer.

Prenatal diagnosis of a case with complete and uniform tetrasomy 12p by the utility of noninvasive prenatal testing

PURPOSE

To report a rare type of Pallister-Killian syndrome (PKS) diagnosed prenatally by the utility of non-invasive prenatal testing (NIPT).

METHODS

NIPT was performed in the first trimester. Conventional karyotyping and chromosomal microarray analysis (CMA) were performed on the amniotic samples in the second trimester. Copy number variation sequencing (CNV-seq) was used for the validation of fetal skin and the placental tissue after pregnancy termination.

RESULTS

NIPT results showed increased signal from chromosome 12p. Subsequent prenatal diagnostic testing by karyotype revealed 47, XY, +i (12p), and CMA displayed four copies of 12p: 12p13.33-12p11.1(173786_34835641) × 4. The CNV-seq results of the fetal skin and the fetal side of placenta showed four copies of 12p13.33-p11 and an estimated chimeric duplication of 34.08 Mb (chimerism ratio: 10%) in 12 p13.33-p11, respectively. However, no abnormality was detected by CNV-seq at the maternal side of placenta.

CONCLUSIONS

Our findings suggest that a positive signal from chromosome 12p on NIPT should raise suspicion for PKS. With the wide application of NIPT, the true positive of incidental finding is expected to increase.

ChIP-seq assay revealed histone modification H3K9ac involved in heat shock response of the sea cucumber Apostichopus japonicus

Heat stress poses an increasing threat for the marine invertebrate Apostichopus japonicus. Histone lysine acetylation is a central chromatin modification for epigenetic regulation of gene expression during stress response. In this study, a genome-wide characterization for acetylated lysine 9 on histone H3 (H3K9ac) binding regions in normal temperature (18 °C) and heat-stress conditions (26 °C) via ChIP-seq were carried out. The results that revealed H3K9ac was an extensive epigenetic modulation in A. japonicus. The GO terms "regulation of transcription, DNA-templated" and "transcription coactivator activity" were significantly enriched in both groups. Particularly, various transcriptional factors (TFs) families showed notable modification of H3K9ac. Differentially acetylated regions (DARs) with H3K9ac modification under heat stress were identified with 24 hyperacetylated and 23 hypoacetylated peaks, respectively. We further examined the transcriptional expression for 13 genes with dysregulated H3K9ac level in the promoter regions by qRT-PCR. Combined H3K9ac ChIP-seq characteristics with the transcriptional expression, 5 up-up genes (ZCCHC3, RPA70, MTRR, β-Gal and PHTF2) and 2 down-down genes (PRPF39 and BSL78_10147) were identified. Surprisingly, the increasing mRNA expression of NECAP1 under heat stress was negatively related to the decreasing H3K9ac level in its promoter region. Our research is the first genome-wide characterization for the epigenetic modification H3K9ac in A. japonicus, and will help to advance the understanding of the roles of H3K9ac in transcriptional regulation under heat-stress condition.

lncRNA LOC339524 inhibits the proliferation of bladder cancer cells by targeting the miR-875-5p/COPS7A signaling axis

It has been reported that long non-coding RNAs (lncRNAs) play a crucial role in the progression of various types of cancer. The role of numerous lncRNAs in a variety of cancer types has been investigated. However, the underlying mechanisms of the majority of lncRNAs in bladder cancer (BCa) remain to be elucidated. In the present study, abnormally expressed lncRNAs in BCa and para-carcinoma tissues were identified through screening the Cancer RNA-Seq Nexus database and were validated using reverse transcription-quantitative PCR. It was found that LOC339524 expression levels were markedly downregulated in BCa tissues and cells (J82, T24, UM-UC-3 and 5637). LOC339524 overexpression was revealed to suppress the proliferation of BCa cells. LOC339524 was also discovered to act as a sponge for microRNA (miR)-875-5p, as identified using dual luciferase reporter assays and biotin pull-down analysis. LOC339524 downregulated the expression of miR-875-5p and knockdown of miR-875-5p expression inhibited the proliferation of bladder cancer cells. In addition, COP9 signalosome subunit 7A (COPS7A) was identified to be the target gene of miR-875-5p and COPS7A expression level was upregulated following LOC339524 overexpression. lncRNA LOC339524 was proposed to function as a competitive endogenous RNA to facilitate the expression of COPS7A by binding to miR-875-5p. In conclusion, the findings of the present study suggested that LOC339524 may inhibit cell proliferation in BCa by targeting the miR-875-5p/COPS7A signaling axis.

A case of a parthenogenetic 46,XX/46,XY chimera presenting ambiguous genitalia

Sex-chromosome discordant chimerism (XX/XY chimerism) is a rare chromosomal disorder in humans. We report a boy with ambiguous genitalia and hypospadias, showing 46,XY[26]/46,XX[4] in peripheral blood cells. To clarify the mechanism of how this chimerism took place, we carried out whole-genome genotyping using a SNP array and microsatellite analysis. The B-allele frequency of the SNP array showed a mixture of three and five allele combinations, which excluded mosaicism but not chimerism, and suggested the fusion of two embryos or a shared parental haplotype between the two parental cells. All microsatellite markers showed a single maternal allele. From these results, we concluded that this XX/XY chimera is composed of two different paternal alleles and a single duplicated maternal genome. This XX/XY chimera likely arose from a diploid maternal cell that was formed via endoduplication of the maternal genome just before fertilization, being fertilized with both X and Y sperm.

Mutation, methylation, and gene expression profiles in dup(1q)-positive pediatric B-cell precursor acute lymphoblastic leukemia

High-throughput sequencing was applied to investigate the mutation/methylation patterns on 1q and gene expression profiles in pediatric B-cell precursor acute lymphoblastic leukemia (BCP ALL) with/without (w/wo) dup(1q). Sequencing of the breakpoint regions and all exons on 1q in seven dup(1q)-positive cases revealed non-synonymous somatic single nucleotide variants (SNVs) in BLZF1, FMN2, KCNT2, LCE1C, NES, and PARP1. Deep sequencing of these in a validation cohort w (n = 17)/wo (n = 94) dup(1q) revealed similar SNV frequencies in the two groups (47% vs. 35%; P = 0.42). Only 0.6% of the 36,259 CpGs on 1q were differentially methylated between cases w (n = 14)/wo (n = 13) dup(1q). RNA sequencing of high hyperdiploid (HeH) and t(1;19)(q23;p13)-positive cases w (n = 14)/wo (n = 52) dup(1q) identified 252 and 424 differentially expressed genes, respectively; only seven overlapped. Of the overexpressed genes in the HeH and t(1;19) groups, 23 and 31%, respectively, mapped to 1q; 60-80% of these encode nucleic acid/protein binding factors or proteins with catalytic activity. We conclude that the pathogenetically important consequence of dup(1q) in BCP ALL is a gene-dosage effect, with the deregulated genes differing between genetic subtypes, but involving similar molecular functions, biological processes, and protein classes.