Transcriptomes of Prostate Cancer with TMPRSS2:ERG and Other ETS Fusions

Chromoplexy: A Pathway to Genomic Complexity and Cancer Development

Chromoplexy is a phenomenon of complex genome rearrangement, occurring during a single cell event and characterized by the formation of chain rearrangements affecting multiple chromosomes. Unlike other genomic rearrangements such as chromothripsis, which involves a single chromosome, chromoplexy affects several chromosomes at once, creating patterns of complex, balanced translocations, and leading to the formation of fusion genes and the simultaneous disruption of several genes. Chromoplexy was first identified in prostate cancers, but it is now observed in various cancers where gene fusions take place. The precise mechanisms behind chromoplexy remain under investigation. The occurrence of these rearrangements follows multiple double-stranded breaks that appear to occur in certain regions or during particular genome configurations (open chromatin, active transcription area), and which lead to an intricate series of inter- and intra-chromosomal translocations and deletions without significant alterations in the number of copies. Although chromoplexy is considered a very early event in oncogenesis, the phenomenon can be repeated and can constitute a mechanism of clonal tumor progression. The occurrence of chromoplexy supports the equilibrium model punctuated by tumor evolution, characterized by periods of relative stability punctuated by sudden and rapid periods of radical genomic changes.

The adult HNRNPH1::ERG positive acute myeloid leukemia with clear lower remission and worse prognosis: A case report and review of the literature

RATIONALE

Acute myeloid leukemia (AML) derived from t(5;21)(q35;q22) translocation, post-transcriptional translation, forming the HNRNPH1::ERG fusion gene is a rare group of recurrent chromosomal abnormality myeloid malignancies. Only 1 adult case of AML has been reported so far. Here we identified a disparate adult case of HNRNPH1::ERG positive AML with clear breakpoint locations by utilizing The RNA sequencing(RNA-seq) and we addressed the clinical, treatment, pathological and molecular mechanism, along with a review of the literature.

PATIENTS CONCERNS

A 54-year-old man visited our department with fever and fatigue for 10 days.

DIAGNOSES

Diagnosed with acute myeloid leukemia (AML) through morphology, immunology, Cytogenetics, and Molecular biology (MICM) typing, with a confirmed HNRNPH1-ERG fusion gene.

INTERVENTIONS

Multiple induction chemotherapy combined with targeted therapy was performed.

OUTCOMES

He died in February 2024.

LESSONS

In our review, Only 1 adult case of AML has been reported so far. To summarize the 5 cases in the studies, the HNRNPH1::ERG positive AML cases had a significantly higher blast cell counts and more frequently companied with rare gene mutations, which characterized poorer prognosis and lower remission in adult HNRNPH1::ERG positive AML.

A complex phylogeny of lineage plasticity in metastatic castration resistant prostate cancer

Aggressive variant and androgen receptor (AR)-independent castration resistant prostate cancers (CRPC) represent the most significant diagnostic and therapeutic challenges in prostate cancer. This study examined a case of simultaneous progression of both adenocarcinoma and squamous tumors from the same common origin. Using whole-genome and transcriptome sequencing from 17 samples collected over >6 years, we established the clonal relationship of all samples, defined shared complex structural variants, and demonstrated both divergent and convergent evolution at AR. Squamous CRPC-associated circulating tumor DNA was identified at clinical progression prior to biopsy detection of any squamous differentiation. Dynamic changes in the detection rate of histology-specific clones in circulation reflected histology-specific sensitivity to treatment. This dataset serves as an illustration of non-neuroendocrine transdifferentiation and highlights the importance of serial sampling at progression in CRPC for the detection of emergent non-adenocarcinoma histologies with implications for the treatment of lineage plasticity and transdifferentiation in metastatic CRPC.

Unraveling the Prognostic Significance of BRCA1-Associated Protein 1 (BAP1) Expression in Advanced and Castrate-Resistant Prostate Cancer

Prostate cancer (PCa) is ranked as one of the top cancers affecting men in Western societies. BRCA1-associated protein 1 (BAP1) expression significance has been observed in various cancers, including prostate cancer. The search for prognostic models allowing better risk stratification and prediction of disease progression in prostate cancer patients is still of major clinical need. Our data showed that nuclear BAP1 expression is the most associated with cancer clinical outcomes and other biomarkers. The data confirmed that decreased BAP1 nuclear expression is linked to aggressive tumors and poorer prognosis. We assessed BAP1 expression in 202 cases, including advanced and castrate-resistant PCa (CRPCa). Our data indicated low BAP1 nuclear expression in advanced and castrate-resistant disease (CRPCa). Furthermore, there was a significant difference between high and low BAP1 nuclear expression relative to the patient's clinical outcome. In the present cohort, decreased BAP1 intensity exhibited a significant association with unfavorable overall survival (OS) (HR 2.31, CI: 1.38-3.86, p = 0.001) and cause-specific survival (CSS) (HR 2.44, CI: 1.24-4.78, p = 0.01). Additionally, this association was more pronounced when low BAP1 expression (high risk) was combined with other common PCa genomic alterations such as phosphatase and tensin homolog (PTEN) loss or ETS-related gene (ERG)-positive cases, resulting in higher unfavorable OS and CSS. Conversely, high BAP1 nuclear expression (moderate and high intensity) combined with no ERG expression or PTEN (moderate or high expression), p53 (wild type), and androgen receptor (AR) (low/moderate intensity) showed better association with higher survival rates. All these data support the notion that BAP1 functions as a tumor suppressor. Integrating BAP1 status with other genomic alterations offers a more comprehensive understanding of disease aggressiveness.

FASN Gene Methylation is Associated with Fatty Acid Synthase Expression and Clinical-genomic Features of Prostate Cancer

Fatty acid synthase (FASN) catalyzes the synthesis of long-chain saturated fatty acids and is overexpressed during prostatic tumorigenesis, where it is the therapeutic target in several ongoing trials. However, the mechanism of FASN upregulation in prostate cancer remains unclear. Here, we examine FASN gene CpG methylation pattern by InfiniumEPIC profiling and whole-genome bisulfite sequencing across multiple racially diverse primary and metastatic prostate cancer cohorts, comparing with FASN protein expression as measured by digitally quantified IHC assay and reverse phase protein array analysis or FASN gene expression. We demonstrate that the FASN gene body is hypomethylated and overexpressed in primary prostate tumors compared with benign tissue, and FASN gene methylation is significantly inversely correlated with FASN protein or gene expression in both primary and metastatic prostate cancer. Primary prostate tumors with ERG gene rearrangement have increased FASN expression and we find evidence of FASN hypomethylation in this context. FASN expression is also significantly increased in prostate tumors from carriers of the germline HOXB13 G84E mutation compared with matched controls, consistent with a report that HOXB13 may contribute to epigenetic regulation of FASN in vitro. However, in contrast to previous studies, we find no significant association of FASN expression or methylation with self-identified race in models that include ERG status across two independent primary tumor cohorts. Taken together, these data support a potential epigenetic mechanism for FASN regulation in the prostate which may be relevant for selecting patients responsive to FASN inhibitors.

SIGNIFICANCE

Here, we leverage multiple independent primary and metastatic prostate cancer cohorts to demonstrate that FASN gene body methylation is highly inversely correlated with FASN gene and protein expression. This finding may shed light on epigenetic mechanisms of FASN regulation in prostate cancer and provides a potentially useful biomarker for selecting patients in future trials of FASN inhibitors.

Emerging Developments in ETS-Positive Prostate Cancer Therapy

Prostate cancer is a global health concern, which has a low survival rate in its advanced stages. Even though second-generation androgen receptor-axis inhibitors serve as the mainstay treatment options, utmost of the metastatic cases progress into castration-resistant prostate cancer after their initial treatment response with poor prognostic outcomes. Hence, there is a dire need to develop effective inhibitors that aim the causal oncogenes tangled in the prostate cancer initiation and progression. Molecular-targeted therapy against E-26 transformation-specific (ETS) transcription factors, particularly ETS-related gene, has gained wide attention as a potential treatment strategy. ETS rearrangements with the male hormone responsive transmembrane protease serine 2 promoter defines a significant number of prostate cancer cases and is responsible for cancer initiation and progression. Notably, inhibition of ETS activity has shown to reduce tumorigenesis, thus highlighting its potential as a clinical therapeutic target. In this review, we recapitulate the various targeted drug approaches, including small molecules, peptidomimetics, nucleic acids, and many others, aimed to suppress ETS activity. Several inhibitors have demonstrated ERG antagonist activity in prostate cancer, but further investigations into their molecular mechanisms and impacts on nontumor ETS-containing tissues is warranted.