The E3 ubiquitin ligase adaptor speckle-type POZ protein (SPOP) is frequently dysregulated in prostate adenocarcinoma (PC), via either somatic mutations or mRNA downregulation, suggesting an ...important tumour suppressor function. To examine its physiologic role in the prostate epithelium in vivo, we generated mice with prostate-specific biallelic ablation of Spop. These mice exhibited increased prostate mass, prostate epithelial cell proliferation, and expression of c-MYC protein compared to littermate controls, and eventually developed prostatic intraepithelial neoplasia (PIN). We found that SPOP
can physically interact with c-MYC protein and, upon exogenous expression in vitro, can promote c-MYC ubiquitination and degradation. This effect was attenuated in PC cells by introducing PC-associated SPOP mutants or upon knockdown of SPOP via short-hairpin-RNA, suggesting that SPOP inactivation directly increases c-MYC protein levels. Gene Set Enrichment Analysis revealed enrichment of Myc-induced genes in transcriptomic signatures associated with SPOP
. Likewise, we observed strong inverse correlation between c-MYC activity and SPOP mRNA levels in two independent PC patient cohorts. The core SPOP
;MYC
transcriptomic response, defined by the overlap between the SPOP
and c-MYC transcriptomic programmes, was also associated with inferior clinical outcome in human PCs. Finally, the organoid-forming capacity of Spop-null murine prostate cells was more sensitive to c-MYC inhibition than that of Spop-WT cells, suggesting that c-MYC upregulation functionally contributes to the proliferative phenotype of Spop knock-out prostates. Taken together, our data highlight SPOP as an important regulator of luminal epithelial cell proliferation and c-MYC expression in prostate physiology, identify c-MYC as a novel bona fide SPOP substrate, and help explain the frequent inactivation of SPOP in human PC. We propose SPOP
-induced stabilization of c-MYC protein as a novel mechanism that can increase total c-MYC levels in PC cells, in addition to amplification of c-MYC locus.
Galectin-3 (Gal-3) is an extracellular matrix glycan-binding protein with several immunosuppressive and pro-tumor functions. The role of Galectin-3 in cancer stem-like cells (CSCs) is poorly ...investigated. Here, we show that prostate CSCs also colonizing prostate-draining lymph nodes of transgenic adenocarcinoma of the mouse prostate (TRAMP) mice overexpress Gal-3. Gal-3 contributes to prostate CSC-mediated immune suppression because either Gal-3 silencing in CSCs, or co-culture of CSCs and T cells in the presence of the Gal-3 inhibitor N-Acetyl-D-lactosamine rescued T cell proliferation. N-Acetyl-D-lactosamine also rescued the proliferation of T cells in prostate-draining lymph nodes of TRAMP mice affected by prostate intraepithelial neoplasia. Additionally, Gal-3 impacted prostate CSC tumorigenic and metastatic potential
, as Gal-3 silencing in prostate CSCs reduced both primary tumor growth and secondary invasion. Gal-3 was also found expressed in more differentiated prostate cancer cells, but with different intracellular distribution as compared to CSCs, which suggests different functions of Gal-3 in the two cell populations. In fact, the prevalent nuclear and cytoplasmic distribution of Gal-3 in prostate CSCs made them less susceptible to apoptosis, when compared to more differentiated prostate cancer cells, in which Gal-3 was predominantly intra-cytoplasmic. Finally, we found Gal-3 expressed in human and mouse prostate intraepithelial neoplasia lesions and in metastatic lymph nodes. All together, these findings identify Gal-3 as a key molecule and a potential therapeutic target already in the early phases of prostate cancer progression and metastasis.
Intraductal carcinoma of the prostate (IDC-P) has been described as a lesion associated with intraductal spread of invasive carcinoma and consequently aggressive disease. However, there are a few ...reported cases of pure IDC-P without an associated invasive component, strongly suggesting that this subset of IDC-P may represent a precursor lesion. We compared the clinicopathological features between the morphologically "regular type" IDC-P and "precursor-like" IDC-P. IDC-P was defined as follows; 1) solid/dense cribriform lesions or 2) loose cribriform/micropapillary lesions with prominent nuclear pleomorphism and/or non-focal comedonecrosis. We defined precursor-like IDC-P as follows; 1) IDC-P without adjoining invasive adenocarcinoma but carcinoma present distant from the IDC-P or 2) IDC-P having adjoining invasive microcarcinoma (less than 0.05 ml) and showing a morphologic transition from high-grade prostatic intraepithelial neoplasia (HGPIN) to the IDC-P. IDC-P lacking the features of precursor-like IDC-P was categorized as regular type IDC-P. Of 901 radical prostatectomies performed at our hospital, 141 and 14 showed regular type IDC-P and precursor-like IDC-P in whole-mounted specimens, respectively. Regular type IDC-P cases had significantly higher Gleason score, more frequent extraprostatic extension and seminal vesicle invasion, more advanced pathological T stage, and lower 5-year biochemical recurrence-free rate than precursor-like IDC-P cases. Multivariate analysis revealed nodal metastasis and the presence of regular type IDC-P as independent predictors for biochemical recurrence. Our data suggest that IDC-P may be heterogeneous with variable clinicopathological features. We also suggest that not all IDC-P cases represent intraductal spread of pre-existing invasive cancer, and a subset of IDC-P may be a precursor lesion.
High-grade prostatic intraepithelial neoplasia (HGPIN) is considered a precursor lesion of prostate cancer (PCa). The predictive value of ERG gene fusion in HGPIN for PCa was interrogated as a post ...hoc analysis in the context of a randomized clinical trial.
The GTx Protocol G300104 randomly assigned 1,590 men with biopsy-diagnosed HGPIN to receive toremifene or placebo for 3 years or until a diagnosis of PCa was made on prostate biopsy. As part of this phase III clinical trial, a central pathologist evaluated biopsies of patients with isolated HGPIN at baseline and 12, 24, and 36 months of follow-up. ERG immunohistochemistry was performed on biopsies from 461 patients and evaluated for protein overexpression.
ERG expression was detected in 11.1% of patients (51 of 461 patients) with isolated HGPIN. In the first year and during the 3-year clinical trial, 14.7% and 36.9% of 461 patients were diagnosed with PCa, respectively. Patients with ERG expression were more likely to develop PCa, with 27 (53%) of 51 ERG-positive and 143 (35%) of 410 ERG-negative patients experiencing progression to PCa (P = .014, Fisher's exact test). ERG expression was not associated with age, baseline PSA, Gleason score, or tumor volume.
This study underscores the necessity of more stringent follow-up for men with HGPIN that is also positive for ERG overexpression. Clinicians should consider molecular characterization of HGPIN as a means to improve risk stratification.
Loss of cellular polarity is a hallmark of epithelial cancers, raising the possibility that regulators of polarity have a role in suppressing tumorigenesis. The Scribble complex is one of at least ...three interacting protein complexes that have a critical role in establishing and maintaining epithelial polarity. In human colorectal, breast, and endometrial cancers, expression of the Scribble complex member SCRIB is often mislocalized and deregulated. Here, we report that Scrib is indispensable for prostate homeostasis in mice. Scrib heterozygosity initiated prostate hyperplasia, while targeted biallelic Scrib loss predisposed mice to prostate intraepithelial neoplasia. Mechanistically, Scrib was shown to negatively regulate the MAPK cascade to suppress tumorigenesis. Further analysis revealed that prostate-specific loss of Scrib in mice combined with expression of an oncogenic Kras mutation promoted the progression of prostate cancer that recapitulated the human disease. The clinical significance of the work in mice was highlighted by our observation that SCRIB deregulation strongly correlated with poor survival in human prostate cancer. These data suggest that the polarity network could provide a new avenue for therapeutic intervention.
Summary
In vitro experiments demonstrated that stimulation of Toll‐like receptor 9 (TLR‐9) by synthetic TLR‐9 ligands induces the invasion of TLR‐9‐expressing prostate cancer cells through matrix ...metalloproteinase 13 (MMP‐13). However, the clinical value of TLR‐9 and MMP‐13 co‐expression in the pathophysiology of the prostate is unknown. In the study, we evaluated the expression levels and clinical significance of the TLR‐9 and MMP‐13 in a series of prostate tissues. One hundred and eighty prostate tissues including prostate cancer (PCa) (n = 137), high‐grade prostatic intraepithelial neoplasia (HPIN) (n = 18) and benign prostatic hyperplasia (BPH) (n = 25) were immunostained for the TLR‐9 and MMP‐13 markers. Subsequently, the correlation between the TLR‐9 and MMP‐13 staining scores and clinicopathological parameters was obtained. Higher expressions of TLR‐9 and MMP‐13 were found in PCa and high‐grade prostatic intraepithelial neoplasia compared to benign prostatic hyperplasia tissues. Among PCa samples, a positive relationship was revealed between the MMP‐13 expression and Gleason score (P < 0.001). There was a significant correlation between TLR‐9 expression and regional lymph node involvement (P = 0.04). The expression patterns of TLR‐9 and MMP‐13 markers demonstrated a reciprocal significant correlation between the two markers in the same series of prostate samples (P < 0.001). Furthermore, the Gleason score of TLR‐9high/MMP‐13high and TLR‐9low/MMP‐13low phenotypes showed a significant difference (P = 0.002). Higher expressions of TLR‐9 and MMP‐13 can confer aggressive behaviour to PCa. Therefore, these markers may be used as a valuable target for tailored therapy of PCa.
Background
The tumor promoting or counteracting effects of the immune response to cancer development are thought to be mediated to some extent by the infiltration of regulatory T cells (Tregs). In ...the present study we evaluated the prevalence of Treg populations in stromal and epithelial compartments of normal, post atrophic hyperplasia (PAH), prostatic intraepithelial neoplasia (PIN), and tumor lesions in men with and without prostate cancer.
Methods
Study subjects were 102 men consecutively diagnosed with localized prostate cancer undergoing radical prostatectomy and 38 men diagnosed with bladder cancer undergoing cystoprostatectomy without prostate cancer at the pathological examination. Whole mount sections from all patients were evaluated for the epithelial and stromal expression of CD4+ Tregs and CD8+ Tregs in normal, PAH, PIN, and tumor lesions. A Friedmańs test was used to investigate differences in the mean number of Tregs across histological lesions. Logistic regression was used to estimate crude and adjusted odds ratios (OR) for prostate cancer for each histological area.
Results
In men with prostate cancer, similarly high numbers of stromal CD4+ Tregs were identified in PAH and tumor, but CD4+ Tregs were less common in PIN. Greater numbers of epithelial CD4+ Tregs in normal prostatic tissue were positively associated with both Gleason score and pT‐stage. We observed a fourfold increased risk of prostate cancer in men with epithelial CD4+ Tregs in the normal prostatic tissue counterpart.
Conclusions
Our results may suggest a possible pathway through which PAH develops directly into prostate cancer in the presence of CD4+ Tregs and indicate that transformation of the anti‐tumor immune response may be initiated even before the primary tumor is established.
The tumor microenvironment plays a critical role in cancer progression, but the precise mechanisms by which stromal cells influence the epithelium are poorly understood. Here we show that p62 levels ...were reduced in the stroma of several tumors and that its loss in the tumor microenvironment or stromal fibroblasts resulted in increased tumorigenesis of epithelial prostate cancer cells. The mechanism involves the regulation of cellular redox through an mTORC1/c-Myc pathway of stromal glucose and amino acid metabolism, resulting in increased stromal IL-6 production, which is required for tumor promotion in the epithelial compartment. Thus, p62 is an anti-inflammatory tumor suppressor that acts through the modulation of metabolism in the tumor stroma.
Display omitted
•p62 levels are reduced in mouse and human tumor stroma•p62 loss in stromal fibroblasts resulted in increased epithelial tumorigenesis•p62 regulates stromal inflammation by mTor/c-Myc metabolic reprogramming•Stromal metabolic reprogramming is essential for IL-6-driven epithelial tumorigenesis
Valencia et al. show that reduced levels of p62 in cancer-associated fibroblasts increase prostate epithelial cell cancer tumorigenesis. They show that p62 modulates stromal cell glucose and amino acid metabolism through an mTORC1/c-Myc pathway, resulting in increased secretion of tumor-promoting IL-6.
Prostate cancer precursors, known as prostate intraepithelial neoplasia (PIN), require abnormal neoplastic cell proliferation to eventually develop into cancer cells. Our study indicated these ...precancerous lesions were able to recruit macrophages through expression of ICAM‐1 and CCR2. Once recruited, infiltrating macrophages secreted C5a, CXCL1, and CCL2 all of which activated ERK signaling in PIN cells to expedite cell proliferation of PIN.
The risk factors for prostate cancer include a high‐fat diet and obesity, both of which are associated with an altered cell environment including increased inflammation. It has been shown that chronic inflammation due to a high‐fat diet or bacterial infection has the potential to accelerate prostate cancer as well as its precursor, prostatic intraepithelial neoplasia (PIN), development. However, the underlying mechanism of how chronic inflammation promotes prostate cancer development, especially PIN, remains unclear. In this study, we showed that more macrophages were present in PIN areas as compared to the normal areas of human prostate. When co‐culturing PIN cells with macrophages in 3D, more PIN cells had nuclear localized cyclin D1, indicating that macrophages enhanced PIN cell proliferation. We identified ICAM‐1 and CCL2 as chemoattractants expressed by PIN cells to recruit macrophages. Furthermore, we discovered that macrophage‐secreted cytokines including C5a, CXCL1, and CCL2 were responsible for increased PIN cell proliferation. These three cytokines activated ERK and JNK signaling in PIN cells through a ligand‐receptor interaction. However, only blockade of ERK abolished macrophage cytokines‐induced cell proliferation of PIN. Overall, our results provide a mechanistic view on how macrophages activated through chronic inflammation can expedite PIN progression during prostate cancer development. The information from our work can facilitate a comprehensive understanding of prostate cancer development, which is required for improvement of current strategies for prostate cancer therapy.
Intraductal carcinoma (IDC) of the prostate is often associated with concurrent high-grade invasive prostate cancer (PCa) and poor clinical outcomes. In this context, IDC is thought to represent the ...retrograde spread of invasive prostatic adenocarcinoma into the acini and ducts. Prior studies have demonstrated a concordance of PTEN loss and genomic instability between the IDC and high-grade invasive components of PCa, but larger genomic association studies to solidify our understanding of the relationship between these 2 lesions are lacking. Here, we evaluate the genomic relationship between duct-confined (high-grade prostatic intraepithelial neoplasia and IDC) and invasive components of high-grade PCa using genetic variants generated by whole exome sequencing. High-grade prostatic intraepithelial neoplasia and IDC were laser-microdissected, and PCa and nonneoplastic tissue was manually dissected from 12 radical prostatectomies. A targeted next-generation sequencing panel was used to identify disease-relevant variants. Additionally, the degree of overlap between adjacent lesions was determined by comparing exome-wide variants detected using whole exome sequencing data. Our results demonstrate that IDC and invasive high-grade PCa components show common genetic variants and copy number alterations. Hierarchical clustering of genome-wide variants suggests that in these tumors, IDC is more closely related to the high-grade invasive components of the tumor compared with high-grade prostatic intraepithelial neoplasia. In conclusion, this study reinforces the concept that, in the context of high-grade PCa, IDC likely represents a late event associated with tumor progression.
PDF
