Quantification and molecular correlates of tertiary lymphoid structures in primary prostate cancer.

OBJECTIVE: To morphologically describe tertiary lymphoid structures (TLS) in prostatectomy specimens and correlate them with clinical and transcriptomic features. METHODOLOGY: A total of 72 consecutive cases of entirely submitted radical prostatectomy (RP) patients tested with the Decipher Genomic Classifier were included in the study. Images were manually annotated using QuPath tools to denote tumor regions and each cluster of TLS. Clusters of lymphocytes that were surrounded on all four sides by tumor were defined as intra-tumor TLS (IT-TLS). Clusters of lymphocytes at the leading edge of carcinoma with either the prostatic pseudocapsule or benign parenchyma at one end were defined as peri-tumor TLS (PT-TLS). A classification algorithm to distinguish lymphocytes from non-lymphocytic cells using a supervised machine learning model was used. The associations between TLS formation and 265 gene expression-based signatures were examined. RESULTS: The magnitude of total TLS correlations with primary tumor gene expression signatures was moderate (~0.35-0.5) with several HLA, T-cell and B-cell Cluster signatures, showing positive correlation with various metrics for quantification of TLS. On the other hand, immune suppressive signatures (Treg, MDSC) were negatively correlated. While signatures for macrophages, NK cells and other immune cell types were uncorrelated for the most part. PT-TLS was associated with MHC signatures while IT TLS correlated with MHC and T-cell signatures. CONCLUSIONS: Clusters of inflammatory cells in the RP specimen can be divided spatially into PT TLS and IT-TLS, each with its unique molecular correlates of tumor immune microenvironment. The presence of TLS is positively correlated with MHC signatures, T- cell and B-cell cluster signatures but, negatively correlated with immune suppressive signatures. A subset of prostate cancer demonstrate a robust inflammatory response, and warrant further characterization in larger cohorts.

Primary Alveolar Soft-Part Sarcoma (ASPS) of the Prostate: Report of a Deceptive Case.

Alveolar soft-part sarcoma (ASPS) is a rare soft tissue tumor that primarily involves the extremities. We report a case of a 30-year-old never-smoker man who presented with hematuria, dysuria, and constipation at an outside hospital. He was diagnosed with and treated for multiple episodes of urinary tract infection. However, he continued to have voiding symptoms for which a cystoscopy was performed and revealed a bladder neck mass. He underwent transurethral resection of a bladder tumor and was diagnosed with muscle-invasive urothelial carcinoma, nested variant, at an outside hospital. Subsequent to this diagnosis he transferred his care to our center. In-house imaging revealed a large vascular mass involving the prostate and pushing against the bladder base. Prostate needle biopsies were performed and revealed an epithelioid neoplasm with a nested growth pattern composed of cells with a moderate amount of eosinophilic cytoplasm, mildly pleomorphic nuclei, and occasional prominent nucleoli. Since the findings were not classic for urothelial carcinoma or for prostate cancer, we included a wider differential of poorly differentiated carcinoma, sarcoma, and paraganglioma. A wide panel of keratin stains was negative, ETS (erythroblast transformation-specific)-related gene highlighted an extensive vascular network and neuroendocrine stains were all negative. A transcription factor E3 fluorescent in-situ hybridization was positive and subsequently, an ASPSCR1 gene rearrangement was demonstrated. The outside hospital transurethral resection of bladder tumor was obtained for review and the tumor was morphologically similar to that seen on the in-house prostate needle biopsies. Based on the above findings a final diagnosis of primary ASPS of the prostate with involvement of the bladder was made. The patient was later diagnosed with bilateral lung metastases. He was treated with pazopanib, radiation therapy, and cystoprostatectomy and is symptom-free on a 15-month follow-up.

Clinicopathologic Spectrum of Secondary Solid Tumors of the Prostate of Nonurothelial Origin: Multi-institutional Evaluation of 85 Cases.

Secondary involvement of the prostate by urothelial or hematolymphoid neoplasms is relatively common and well-described. In contrast, less is known about the clinicopathologic spectrum of secondary solid tumors of the prostate of nonurothelial origin. This study evaluated a series of secondary nonurothelial solid tumors of the prostate diagnosed at 21 institutions. Eighty-five patients with a median age at diagnosis of 64 years were included. Sixty-two patients had clinically manifest disease (62/85, 73%), 10 were diagnosed incidentally (10/85, 12%), and 13 (13/85, 15%) had no detailed clinical data available about symptomatology at presentation. Among patients with clinically manifest disease, the most common symptoms and signs were lower urinary tract symptoms (either obstructive of irritative; 36/62, 58%), abdominal or pelvic pain or discomfort (16/62, 26%), and hematuria (12/62, 19%). Metastasis and direct invasion occurred at roughly similar frequencies (47% vs. 42%) in this series, and in 11% of the cases, the mechanism of spread to the prostate was unclear/uncertain. Overall, among tumors with confirmed sites of origin, the most common primary sites were gastrointestinal tract (53/85, 62%), lung (9/85, 11%), skin (6/85, 7%), and testis (4/85, 5%). Among metastases, the most common tumor types were lung carcinomas (9/40, 23%), colorectal adenocarcinomas (7/40, 18%), melanoma (6/40, 15%), and germ cell tumors (6/40, 15%). This study demonstrated that secondary involvement of the prostate by solid tumors of nonurothelial origin is commonly symptomatic and that the most frequent sites of origin are the gastrointestinal tract, lung, skin, and testis. These findings are worth considering when lesions with unusual cytomorphology and/or architecture are encountered in prostate specimens.

PROTEIN KINASE C ALPHA IS A CENTRAL NODE FOR TUMORIGENIC TRANSCRIPTIONAL NETWORKS IN HUMAN PROSTATE CANCER.

Aberrant expression of protein kinase C (PKC) isozymes is a hallmark of cancer. The different members of the PKC family control cellular events associated with cancer development and progression. Whereas the classical/conventional PKCα isozyme has been linked to tumor suppression in most cancer types, here we demonstrate that this kinase is required for the mitogenic activity of aggressive human prostate cancer cells displaying aberrantly high PKCα expression. Immunohistochemical analysis showed abnormal up-regulation of PKCα in human primary prostate tumors. Interestingly, silencing PKCα expression from aggressive prostate cancer cells impairs cell cycle progression, proliferation and invasion, as well as their tumorigenic activity in a mouse xenograft model. Mechanistic analysis revealed that PKCα exerts a profound control of gene expression, particularly over genes and transcriptional networks associated with cell cycle progression and E2F transcription factors. PKCα RNAi depletion from PC3 prostate cancer cells led to a reduction in the expression of pro-inflammatory cytokine and epithelial-to-mesenchymal transition (EMT) genes, as well as a prominent down-regulation of the immune checkpoint ligand PD-L1. This PKCα-dependent gene expression profile was corroborated in silico using human prostate cancer databases. Our studies established PKCα as a multifunctional kinase that plays pleiotropic roles in prostate cancer, particularly by controlling genetic networks associated with tumor growth and progression. The identification of PKCα as a pro-tumorigenic kinase in human prostate cancer provides strong rationale for the development of therapeutic approaches towards targeting PKCα or its effectors.