Background: This study explores the potential for hidden variations within seemingly uniform regions of growth hormone-secreting pituitary neuroendocrine tumors (GH-PitNETs). We employed archived tissue samples using Laser Capture Microdissection Sequencing (LCM-RNAseq) to probe the molecular landscape of these tumors at a deeper level. Methods: A customized protocol was developed to extract, process, and sequence small amounts of RNA from formalin-fixed, paraffin-embedded (FFPE) tissues derived from five patients with GH-secreting PitNETs and long-term follow-up (≥10 years). This approach ensured precise isolation of starting material of enough quality for subsequent sequencing. Results: The LCM-RNAseq analysis revealed a surprising level of diversity within seemingly homogeneous tumor regions. Interestingly, the 30 most highly expressed genes included the well-known long noncoding RNA (lncRNA) MALAT1. We further validated the levels of MALAT1 and of other tumor-associated lncRNAs using digital droplet PCR. Conclusions: This study demonstrates the potential of LCM-RNAseq to unlock hidden molecular diversity within archived pituitary tumor samples. By focusing on specific cell populations, we identified lncRNAs expressed at different levels within the tumors, potentially offering new insights into the complex biology of GH-secreting PitNETs. This evidence prompts further research into the role of lncRNAs in pituitary neuroendocrine tumor aggressiveness and personalized treatment strategies.

The alteration of the lysine acetyltransferase activity and protein–protein interactions of the transcriptional co‐activators CREB‐binding protein (CBP) and p300 is linked to the development of both solid and hematological cancers. To target both functions of CBP/p300, two PROTAC‐based chemical degraders are developed by linking the CBP/p300 catalytic inhibitor C646 and the Cereblon (CRBN) ligand thalidomide via polyethylene glycol‐based linkers. Both compounds exhibit submicromolar inhibition of CBP/p300 and decrease their levels in the SU‐DHL‐10 lymphoma cell line at low‐micromolar concentrations. Moreover, it is demonstrated that compound 1 recruits CBP/p300 and CRBN in cells and acts as a bona fide PROTAC degrader of CBP/p300 via the ubiquitin‐proteasome pathway. Finally, both compounds exhibit low‐micromolar antiproliferative activity in different lymphoma cell lines and are more potent than C646. Overall, it is demonstrated that the PROTAC strategy is a viable option for targeting CBP/p300 in lymphoma and identifies compound 1 as a promising chemical tool and lead compound for further studies.

Background/Objectives: Metastatic prostate cancer (PCa) remains a major clinical challenge with limited therapeutic options. The long non-coding RNA H19 has been implicated in regulating cell adhesion molecules and collective migration, key features of metastatic dissemination. This study investigates the role of the Bromodomain and Extra-Terminal (BET) proteins BRD2, BRD3, and BRD4 in the H19-dependent transcriptional regulation of cell adhesion molecules. Currently, the major effects of BET inhibitors require androgen receptor (AR) expression. Methods: H19 was stably silenced in PC-3 (AR-null) and 22Rv1 (AR-positive) castration-resistant PCa cells. The cells were treated with the pan-BET inhibitors JQ1 and OTX015 or the BET degrader dBET6. In vivo, the effects of JQ1 were evaluated in xenograft mouse models. Chromatin immunoprecipitation (ChIP) and RNA-ChIP were used to assess BET protein recruitment and interaction with cell adhesion gene loci and H19. Organotypic slice cultures (OSCs) from fresh PCa surgical specimens were used as ex vivo models to validate transcriptional changes and BRD4 recruitment. Results: BET inhibition significantly reduced the expression of β4 integrin and E-cadherin and cell proliferation in both basal conditions, and following H19 knockdown in PC-3 and 22Rv1 cells. These effects were mirrored in JQ1-treated tumor xenografts, which showed marker downregulation and tumor regression. ChIP assays revealed that BRD4, more than BRD2/3, was enriched on β4 integrin and E-cadherin promoters, especially in regions marked by H3K27ac. H19 silencing markedly enhanced BRD4 promoter occupancy. RNA-ChIP confirmed a specific interaction between BRD4 and H19. These findings were validated in OSCs, reinforcing their clinical relevance. Conclusions: Our study demonstrates that BRD4 epigenetically regulates the H19-mediated transcriptional control of adhesion molecules involved in collective migration and metastatic dissemination. Importantly, these effects are independent of AR status, suggesting that targeting the H19/BRD4 axis may represent a promising therapeutic avenue for advanced PCa.

Background: Preclinical models that preserve the tumor microenvironment are critically needed in prostate cancer (PCa) research. Patient-derived xenografts (PDXs) and patient-derived Organotypic Slice Cultures (PD-OSCs) have emerged as promising in vivo and ex vivo platforms to address this gap and better mimic human tumor biology. Methods: Subcutaneous PDX models and PD-OSCs were established in parallel from fresh, primary hormone-naïve PCa patient tissues. PDX models were generated by engrafting tumor fragments into immunodeficient mice, while PD-OSCs were maintained as short-term ex vivo cultures for functional analysis. Results: A cohort of 64 PDXs and 45 PD-OSCs was generated. While first-generation PDX engraftment was successful, subsequent passaging and model expansion were extremely poor. In contrast, PD-OSCs were reliably established, maintained tissue viability, and proved to be a robust platform for functional testing, including gene expression analysis and drug sensitivity screening. Conclusions: Our findings establish both first-generation PDXs and PD-OSCs as valuable “avatar” models for translational research. However, PD-OSCs represent a more efficient and rapid platform for studying primary hormone-naïve PCa biology and evaluating treatment responses, holding significant promise as a predictive tool to guide personalized medicine.

Introduction: Metastatic prostate cancer (PCa) presents a significant challenge in oncology due to its high mortality rate and the absence of effective biomarkers for predicting patient outcomes. Building on previous research that highlighted the critical role of the long noncoding RNA (lncRNA) H19 and cell adhesion molecules in promoting tumor progression under hypoxia and estrogen stimulation, this study aimed to assess the potential of these components as prognostic biomarkers for PCa at the biopsy stage. Methods: This research utilized immunohistochemistry and droplet digital PCR to analyze formalin-fixed paraffin-embedded (FFPE) biopsies, focusing on specific markers within the H19/cell adhesion molecules pathway. Results: A novel multivariate analysis led to a “BioScore”, a composite biomarker score to predict disease progression. This score is based on evaluating five key markers: the expression levels of Hypoxia-Inducible Factor 2 Alpha (HIF-2α), endothelial Nitric Oxide Synthase (eNOS), β4 integrin, E-cadherin transcript (CDH1), and lncRNA H19. The criteria for the “BioScore” involve identifying three out of these five markers, combining elevated levels of HIF-2α, eNOS, β4 integrin, and CDH1 with reduced H19 expression. Conclusions: This finding suggests the possibility of identifying, at the time of biopsy, PCa patients at higher risk of metastasis based on dysregulation in the H19/cell adhesion molecules circuitry. This study provides a valuable opportunity for early intervention in managing PCa, potentially contributing to personalized treatment strategies.