Gene expression profiling in porocarcinoma indicates heterogeneous tumor development and substantiates poromas as precursor lesions.

BACKGROUND AND OBJECTIVES: Malignant sweat gland tumors are rare, with the most common being eccrine porocarcinoma (EP). Approximately 18% of benign eccrine poroma (EPO) transit to EP. Previous research has provided first insights into the mutational landscape of EP. However, only few studies have performed gene expression analyses. This leaves a gap in the understanding of EP biology and potential drivers of malignant transformation from EPO to EP. METHODS: Transcriptome profiling of 23 samples of primary EP and normal skin (NS). Findings from the EP samples were then tested in 17 samples of EPO. RESULTS: Transcriptome profiling revealed diversity in gene expression and indicated biologically heterogeneous sub-entities as well as widespread gene downregulation in EP. Downregulated genes included CD74, NDGR1, SRRM2, CDC42, ANXA2, KFL9 and NOP53. Expression levels of CD74, NDGR1, SRRM2, ANXA2, and NOP53 showed a stepwise-reduction in expression from NS via EPO to EP, thus supporting the hypothesis that EPO represents a transitional state in EP development. CONCLUSIONS: We demonstrated that EP is molecularly complex and that evolutionary trajectories correspond to tumor initiation and progression. Our results provide further evidence implicating the p53 axis and the EGFR pathway. Larger samples are warranted to confirm our findings.

Noncancer-related Secondary Findings in a Cohort of 231 Children With Cancer and Their Parents.

Application of next-generation sequencing may lead to the detection of secondary findings (SF) not related to the initially analyzed disease but to other severe medically actionable diseases. However, the analysis of SFs is not yet routinely performed. We mined whole-exome sequencing data of 231 pediatric cancer patients and their parents who had been treated in our center for the presence of SFs. By this approach, we identified in 6 children (2.6%) pathogenic germline variants in 5 of the noncancer-related genes on the American College of Medical Genetics and Genomics (ACMG) SF v3.0 list, of which the majority were related to cardiovascular diseases ( RYR2 , MYBPC3 , KCNQ1 ). Interestingly, only the patient harboring the KCNQ1 variant showed at the time point of the analysis signs of the related Long QT syndrome. Moreover, we report 3 variants of unknown significance which, although not classified as pathogenic, have been reported in the literature to occur in individuals with the respective disease. While the frequency of patients with SFs is low, the impact of such findings on the patients' life is enormous, with regard to the potential prevention of life-threatening diseases. Hence, we are convinced that such actionable SF should be routinely analyzed.

Identification and characterization of novel associations in the CASP8/ALS2CR12 region on chromosome 2 with breast cancer risk.

Previous studies have suggested that polymorphisms in CASP8 on chromosome 2 are associated with breast cancer risk. To clarify the role of CASP8 in breast cancer susceptibility, we carried out dense genotyping of this region in the Breast Cancer Association Consortium (BCAC). Single-nucleotide polymorphisms (SNPs) spanning a 1 Mb region around CASP8 were genotyped in 46 450 breast cancer cases and 42 600 controls of European origin from 41 studies participating in the BCAC as part of a custom genotyping array experiment (iCOGS). Missing genotypes and SNPs were imputed and, after quality exclusions, 501 typed and 1232 imputed SNPs were included in logistic regression models adjusting for study and ancestry principal components. The SNPs retained in the final model were investigated further in data from nine genome-wide association studies (GWAS) comprising in total 10 052 case and 12 575 control subjects. The most significant association signal observed in European subjects was for the imputed intronic SNP rs1830298 in ALS2CR12 (telomeric to CASP8), with per allele odds ratio and 95% confidence interval [OR (95% confidence interval, CI)] for the minor allele of 1.05 (1.03-1.07), P = 1 × 10(-5). Three additional independent signals from intronic SNPs were identified, in CASP8 (rs36043647), ALS2CR11 (rs59278883) and CFLAR (rs7558475). The association with rs1830298 was replicated in the imputed results from the combined GWAS (P = 3 × 10(-6)), yielding a combined OR (95% CI) of 1.06 (1.04-1.08), P = 1 × 10(-9). Analyses of gene expression associations in peripheral blood and normal breast tissue indicate that CASP8 might be the target gene, suggesting a mechanism involving apoptosis.

Whole-exome sequencing in eccrine porocarcinoma indicates promising therapeutic strategies.

Malignant sweat gland tumours are rare, with the most common form being Eccrine porocarcinoma (EP). To investigate the mutational landscape of EP, we performed whole-exome sequencing (WES) on 14 formalin-fixed paraffin-embedded samples of matched primary EP and healthy surrounding tissue. Mutational profiling revealed a high overall median mutation rate. This was attributed to signatures of mutational processes related to ultraviolet (UV) exposure, APOBEC enzyme dysregulation, and defective homologous double-strand break repair. All of these processes cause genomic instability and are implicated in carcinogenesis. Recurrent driving somatic alterations were detected in the EP candidate drivers TP53, FAT2, CACNA1S, and KMT2D. The analyses also identified copy number alterations and recurrent gains and losses in several chromosomal regions including that containing BRCA2, as well as deleterious alterations in multiple HRR components. In accordance with this reduced or even a complete loss of BRCA2 protein expression was detected in 50% of the investigated EP tumours. Our results implicate crucial oncogenic driver pathways and suggest that defective homologous double-strand break repair and the p53 pathway are involved in EP aetiology. Targeting of the p53 axis and PARP inhibition, and/or immunotherapy may represent promising treatment strategies.

Germline mutations of the MSR1 gene in prostate cancer families from Germany.

The MSR1 gene at 8p22 has been suggested as a candidate gene for hereditary prostate cancer because germline variants have been found to be associated with the disease. Aside from a single nonsense mutation (R293X) that was found repeatedly at low frequencies in several samples, little evidence has been gained by follow-up studies to confirm the gene's relevance for prostate cancer. Prompted by reasonable support for a linkage to 8p22, we sought to determine the mutation spectrum of MSR1 in our family sample. Screening of 139 probands (representing 139 prostate cancer families) revealed 15 novel and a total of 20 sequence variants within the 10 coding exons and their intronic proximities. Aside from the known mutation c.877C>T (R293X) present in two of our families, we identified a second nonsense allele (c.251C>G; S84X) and a splice-site mutation (c.818-1G>A) that results in mRNA instability (each in a single pedigree). The novel missense alleles were c.703C>T (H235Y), c.856C>T (P286S), c.905C>T (P302L), c.1193C>G (A398G), and c.1289A>G (K430R). Of the eight variants that affect the encoded protein (splice site, nonsense, and missense), only R293X as well as the polymorphism c.823C>G (P275A) were additionally present at remarkable frequencies in further samples of sporadic prostate cancer and controls. Of note, carriers of R293X were equally frequent in 367 sporadic prostate cancer cases (1.9%) and in 197 controls (2.0%). To our knowledge, our study is the first to demonstrate further loss of function variants of MSR1 apart from R293X. Nevertheless, the low frequencies of deleterious alleles, in addition to an apparently moderate penetrance, does not support MSR1 as a major susceptibility gene in this family sample.

The prostate cancer risk locus at 10q11 is associated with DNA repair capacity.

Genome-wide association studies (GWAS) have identified several single nucleotide polymorphisms (SNPs) that mildly predict prostate cancer risk. These SNPs are local tagging markers for causal gene alterations. Consideration of candidate genes in the tagged regions would be facilitated by additional information on the particular pathomechanisms which contribute to the observed risk increase. In this study we test for an association of prostate cancer tagging SNPs with alterations in DNA repair capacity, a phenotype that is frequently involved in cancer predisposition. DNA repair capacity was assessed on blood lymphocytes from 128 healthy probands after ionizing irradiation. We used the micronucleus (MN) assay to determine the cellular DNA double-strand break repair capacity and flow cytometry to measure damage induced mitotic delay (MD). Probands were genotyped for a panel of 14 SNPs, each representing an independent prostate cancer risk locus previously identified by GWAS. Associations between germline variants and DNA repair capacity were found for the SNPs rs1512268 (8p21), rs6983267 (8q24) and rs10993994 (10q11). The most significant finding was an association of homozygous rs10993994 T-allele carriers with a lower MN frequency (p=0.0003) and also a decreased MD index (p=0.0353). Cells with prostate cancer risk alleles at rs10993994 seem to cope more efficiently with DNA double strand breaks (less MN) in a shorter time (decreased MD index). This intriguing finding imposes concern about the accuracy of repair, with respect to the cancer risk that is mediated by T genotypes. To date, MSMB (microseminoprotein ß) is favored as the causal gene at the 10q11 risk locus, since it was the first candidate gene known to be expressionally altered by rs10993994. Based on the present observation, candidate genes from the contexts of DNA repair and apoptosis may be more promising targets for expression studies with respect to the rs10993994 genotype.

Predisposition for TMPRSS2-ERG fusion in prostate cancer by variants in DNA repair genes.

The somatic fusion of TMPRSS2 to ETS oncogenes is a common event in prostate cancer (PCa). We hypothesized that defects in DNA repair may lead to an increase of chromosomal rearrangements and thus to the occurrence of ETS oncogene fusion. We have previously conducted a genome-wide linkage analysis in TMPRSS2-ERG fusion-positive PCa families, revealing potential susceptibility loci on chromosomes 5q14, 9q21, 10q26, 11q24, 12q15, 13q12, 18q, and Xq27. In the present study, nine candidate genes from these regions were selected from the context of DNA repair and screened for mutations in TMPRSS2-ERG fusion-positive families. Thirteen nonsynonymous variants, 5 of which had a minor allele frequency of <0.05, were genotyped in 210 familial cases, 47 of which with a known TMPRSS2-ERG status, 329 sporadic cases, and 512 controls. Significant association of TMPRSS2-ERG fusion-positive PCa was found with rare variants in the genes for POLI [variant F532S: P = 0.0011; odds ratios (OR), 4.62; 95% confidence interval (95% CI), 1.84-11.56] and ESCO1 (variant N191S: P = 0.0034; OR, 4.27; 95% CI, 1.62-11.28). Additional findings, regardless of TMPRSS2-ERG status, were the overrepresentation of a rare BRCA2 variant (V2728I: P = 0.03; OR, 6.16; 95% CI, 1.19-32.00) in familial PCa and of a common allele of RMI1 (variant N455S: P = 0.02; OR, 1.33; 95% CI, 1.04-1.70) in unselected PCa cases. The DNA repair genes POLI and ESCO1 are proposed as susceptibility genes for TMPRSS2-ERG fusion-positive PCa that warrant further investigation.