Endometrial, Ovarian, and Peritoneal Involvement by Endometrioid Carcinoma, Yolk Sac Tumor, and Endometriosis: Molecular Evidence for a Shared Precursor.

Recent studies have provided molecular confirmation that a subset of yolk sac tumors is somatically derived. Somatically derived yolk sac tumors are typically diagnosed in older women and are often seen adjacent to epithelial proliferations (such as endometriosis or endometrioid carcinoma) with which they share mutations. Here, we present a case of a postmenopausal woman with a yolk sac tumor and endometriosis in the right ovary, endometriosis with glandular crowding and reactive changes in the left ovary, endometrial endometrioid carcinoma, and yolk sac tumor involving the serosa of the colon. Targeted next-generation sequencing of these five tumor components demonstrated identical mutations in PTEN (p.R130G), PIK3CA (p.G1049S), FGFR2 (p.S252W), and FBXW7 (p.R689Q), suggesting that all components arose from a common precursor. The endometrial endometrioid carcinoma harbored additional exclusive mutations involving PIK3CA (p.H1048R) and CTNNB1 (p.S37F).

Truncated ERG Oncoproteins from TMPRSS2-ERG Fusions Are Resistant to SPOP-Mediated Proteasome Degradation.

SPOP mutations and TMPRSS2-ERG rearrangements occur collectively in up to 65% of human prostate cancers. Although the two events are mutually exclusive, it is unclear whether they are functionally interrelated. Here, we demonstrate that SPOP, functioning as an E3 ubiquitin ligase substrate-binding protein, promotes ubiquitination and proteasome degradation of wild-type ERG by recognizing a degron motif at the N terminus of ERG. Prostate cancer-associated SPOP mutations abrogate the SPOP-mediated degradation function on the ERG oncoprotein. Conversely, the majority of TMPRSS2-ERG fusions encode N-terminal-truncated ERG proteins that are resistant to the SPOP-mediated degradation because of degron impairment. Our findings reveal degradation resistance as a previously uncharacterized mechanism that contributes to elevation of truncated ERG proteins in prostate cancer. They also suggest that overcoming ERG resistance to SPOP-mediated degradation represents a viable strategy for treatment of prostate cancers expressing either mutated SPOP or truncated ERG.

Integrated analysis of the genomic instability of PTEN in clinically insignificant and significant prostate cancer.

Patients with clinically insignificant prostate cancer remain a major over-treated population. PTEN loss is one of the most recurrent alterations in prostate cancer associated with an aggressive phenotype, however, the occurrence of PTEN loss in insignificant prostate cancer has not been reported and its role in the separation of insignificant from significant prostate cancer is unclear. An integrated analysis of PTEN loss was, therefore, performed for structural variations, point mutations and protein expression in clinically insignificant (48 cases) and significant (76 cases) prostate cancers treated by radical prostatectomy. Whole-genome mate pair sequencing was performed on tumor cells isolated by laser capture microdissection to characterize PTEN structural alterations. Fluorescence in situ hybridization probes were constructed from the sequencing data to detect the spectrum of these PTEN alterations. PTEN loss by mate pair sequencing and fluorescence in situ hybridization occurred in 2% of insignificant, 13% of large volume Gleason score 6, and 46% of Gleason score 7 and higher cancers. In Gleason score 7 cancers with PTEN loss, PTEN alterations were detected in both Gleason pattern 3 and 4 in 57% of cases by mate pair sequencing, 75% by in situ hybridization and 86% by immunohistochemistry. PTEN loss by sequencing was strongly associated with TMPRSS2-ERG fusion, biochemical recurrence, PTEN loss by in situ hybridization and protein loss by immunohistochemistry. The complex nature of PTEN rearrangements was unveiled by sequencing, detailing the heterogeneous events leading to homozygous loss of PTEN. PTEN point mutation was present in 5% of clinically significant tumors and not in insignificant cancer or high-grade prostatic intraepithelial neoplasia. PTEN loss is infrequent in clinically insignificant prostate cancer, and is associated with higher grade tumors. Detection of PTEN loss in Gleason score 6 cancer in a needle biopsy specimen indicates a higher likelihood of clinically significant prostate cancer.

Shared and unique genomic structural variants of different histological components within testicular germ cell tumours identified with mate pair sequencing.

Post-pubertal testicular germ-cell tumours (TGCTs) can present with a variety of distinct histologies which are nevertheless lineage related and often co-occurring. The exact lineage relationships and developmental pathways leading to the different histologies is debated. In order to investigate the relationship of histologic populations, mate-pair sequencing (MPseq) and exome sequencing (ExomeSeq) were conducted on different histological populations within the same tumour. Ten TGCTs with 1-3 histologic types/tumour were sequenced. Junctions of somatic chromosomal rearrangements were identified on a per genome basis, with germ cell neoplasia in situ possessing the least (median 1, range 0-4) and embryonal carcinoma the most (median 8.5, range 6-12). Copy number variation revealed gains and losses, including isoform 12p (i12p) (10/10 samples), and chromosomes 7, 8, and 21 gains (7/10 samples). Mapping of shared junctions within a tumour revealed lineage relationships, but only i12p was shared between patients. ExomeSeq from two cases demonstrated a high level of copy-neutral loss of heterozygosity. Parallel assessment of separate histologies within a single TGCT demonstrated cumulative and divergent changes, suggesting the importance of parallel sequencing for detection of relevant biomarkers.

Using Genomics to Differentiate Multiple Primaries From Metastatic Lung Cancer.

INTRODUCTION: Genomic technologies present a promising mechanism of resolving the clinical dilemma of distinguishing independent primary tumors from intrapulmonary metastases in NSCLC. We evaluated the utility of discordant mapping somatic junctions from chromosomal rearrangements in diagnosing metastatic disease compared to the current standard histologic review. MATERIAL AND METHODS: Mate-pair sequencing was performed on DNA extracted from 76 distinct tumors from 37 cases of multiple lung cancers. Discordant mapping junctions and chromosomal copy levels were assessed for each tumor. Blood-derived DNA was available on 22 of these cases for germline assessments. A lung cancer next-generation sequencing panel was additionally performed on tumor pairs from 17 patients. RESULTS: Whereas mate-pair sequencing was able to classify lineage in all tumor pairs, histologic review appeared to misclassify lineage in 9 of 33 (27%) same-histology tumor pair comparisons. Based on disagreement between the reviewing pathologists, histopathologic lineage was classified as indeterminate in seven cases. In two cases where pathologists agreed on a metastatic call, no shared junctions were found suggesting independent primaries. Although germline junctions passing algorithmic filters were common, on average less than three were present and all had predictable structures of small focal rearrangements or transposons. Evaluation of shared chromosomal copy changes and driver mutations through a lung cancer next-generation sequencing panel, while informative, were nondefinitive in calling lineage in all cases. CONCLUSIONS: The highly unique nature and prevalence of chromosomal rearrangement in lung cancers provide a useful and definitive technique for calling lineage in multifocal lung cancer.

Quantification of Somatic Chromosomal Rearrangements in Circulating Cell-Free DNA from Ovarian Cancers.

Recently, the use of a liquid biopsy has shown promise in monitoring tumor burden. While point mutations have been extensively studied, chromosomal rearrangements have demonstrated greater tumor specificity. Such rearrangements can be identified in the tumor and subsequently detected in the plasma of patients using quantitative PCR (qPCR). In this study we used a whole-genome mate-pair protocol to characterize a landscape of genomic rearrangements in the primary tumors of ten ovarian cancer patients. Individualized tumor-specific primer panels of aberrant chromosomal junctions were identified for each case and detected by qPCR within the cell-free DNA. Selected chromosomal junctions were detected in pre-surgically drawn blood in eight of the ten patients. Of these eight, three demonstrated the continued presence of circulating tumor DNA (ctDNA) post-surgery, consistent with their documented presence of disease, and in five ctDNA was undetectable in the post-surgical blood collection, consistent with their lack of detectable disease. The ctDNA fraction was calculated using a novel algorithm designed for the unique challenges of quantifying ctDNA using qPCR to allow observations of real-time tumor dynamics. In summary, a panel of individualized junctions derived from tumor DNA could be an effective way to monitor cancer patients for relapse and therapeutic efficacy using cfDNA.

Integrated Genomic Analysis of Pancreatic Ductal Adenocarcinomas Reveals Genomic Rearrangement Events as Significant Drivers of Disease.

Many somatic mutations have been detected in pancreatic ductal adenocarcinoma (PDAC), leading to the identification of some key drivers of disease progression, but the involvement of large genomic rearrangements has often been overlooked. In this study, we performed mate pair sequencing (MPseq) on genomic DNA from 24 PDAC tumors, including 15 laser-captured microdissected PDAC and 9 patient-derived xenografts, to identify genome-wide rearrangements. Large genomic rearrangements with intragenic breakpoints altering key regulatory genes involved in PDAC progression were detected in all tumors. SMAD4, ZNF521, and FHIT were among the most frequently hit genes. Conversely, commonly reported genes with copy number gains, including MYC and GATA6, were frequently observed in the absence of direct intragenic breakpoints, suggesting a requirement for sustaining oncogenic function during PDAC progression. Integration of data from MPseq, exome sequencing, and transcriptome analysis of primary PDAC cases identified limited overlap in genes affected by both rearrangements and point mutations. However, significant overlap was observed in major PDAC-associated signaling pathways, with all PDAC exhibiting reduced SMAD4 expression, reduced SMAD-dependent TGFß signaling, and increased WNT and Hedgehog signaling. The frequent loss of SMAD4 and FHIT due to genomic rearrangements strongly implicates these genes as key drivers of PDAC, thus highlighting the strengths of an integrated genomic and transcriptomic approach for identifying mechanisms underlying disease initiation and progression.

Identification of independent primary tumors and intrapulmonary metastases using DNA rearrangements in non-small-cell lung cancer.

PURPOSE: Distinguishing independent primary tumors from intrapulmonary metastases in non-small-cell carcinoma remains a clinical dilemma with significant clinical implications. Using next-generation DNA sequencing, we developed a chromosomal rearrangement-based approach to differentiate multiple primary tumors from metastasis. METHODS: Tumor specimens from patients with known independent primary tumors and metastatic lesions were used for lineage test development, which was then applied to multifocal tumors. Laser capture microdissection was performed separately for each tumor. Genomic DNA was isolated using direct in situ whole-genome amplification methodology, and next-generation sequencing was performed using an Illumina mate-pair library protocol. Sequence reads were mapped to the human genome, and primers spanning the fusion junctions were used for validation polymerase chain reaction. RESULTS: A total of 41 tumor samples were sequenced (33 adenocarcinomas [ADs] and eight squamous cell carcinomas [SQCCs]), with a range of three to 276 breakpoints per tumor identified. Lung tumors predicted to be independent primary tumors based on different histologic subtype did not share any genomic rearrangements. In patients with lung primary tumors and paired distant metastases, shared rearrangements were identified in all tumor pairs, emphasizing the patient specificity of identified breakpoints. Multifocal AD and SQCC samples were reviewed independently by two pulmonary pathologists. Concordance between histology and genomic data occurred in the majority of samples. Discrepant tumor samples were resolved by genome sequencing. CONCLUSION: A diagnostic lineage test based on genomic rearrangements from mate-pair sequencing demonstrates promise for distinguishing independent primary from metastatic disease in lung cancer.