Treatment of prostate cancer (PC) by androgen suppression promotes the emergence of aggressive variants that are androgen receptor- (AR-) independent. Here we identify the transcription factor ONECUT2 (OC2) as a master regulator of AR networks in metastatic castration-resistant prostate cancer (mCRPC). OC2 acts as a survival factor in mCRPC models, suppresses the AR transcriptional program by direct regulation of AR target genes and the AR licensing factor FOXA1, and activates genes associated with neural differentiation and progression to lethal disease. OC2 appears active in a substantial subset of human prostate adenocarcinoma and neuroendocrine tumors. Inhibition of OC2 by a newly identified small molecule suppresses metastasis in mice. These findings suggest that OC2 displaces AR-dependent growth and survival mechanisms in many cases where AR remains expressed, but where its activity is bypassed. OC2 is also a potential drug target in the metastatic phase of aggressive PC.

PURPOSE To assess the application of near-infrared (NIR) heptamethine carbocyanine dyes, IR-783 and the synthetic analog MHI-148, as optical imaging agents for rapid detection of human kidney cancer. MATERIALS AND METHODS The uptake, retention and subcellular localization of these organic dyes were investigated in cultured kidney cancer cells. Tumor specificity of dye uptake and retention was evaluated by whole-body imaging of mice bearing human kidney cancer xenografts or freshly harvested clinical kidney cancer specimens. In addition, dye accumulation at the tissue and cellular levels was confirmed by ex vivo studies with results confirmed by fluorescence imaging of the frozen tissue sections. Peripheral blood spiked with kidney cancer cells was stained to simulate the detection of circulating tumor cells. RESULTS Preferential uptake and retention of carbocyanine NIR dyes was observed in cultured human kidney cancer cells, human kidney cancer cell-spiked whole blood, human kidney cancer xenografts and freshly harvested human kidney cancer tissues compared to normal kidney epithelial cells or normal host organs. CONCLUSIONS We described a new class of NIR heptamethine carbocyanine dyes showing potential for detecting kidney cancer cells in circulating blood and kidney cancer cells in clinical specimens. NIR carbocyanine dyes can be further developed as dual modality agents for deep-tissue imaging of localized and disseminated kidney cancer in patients.

We have previously shown that human prostate cancer cells are capable of acquiring malignant attributes through interaction with stromal cells in the tumor microenvironment, while the interacting stromal cells can also become affected with both phenotypic and genotypic alterations. This study used a co-culture model to investigate the mechanism underlying the co-evolution of cancer and stromal cells. Red fluorescent androgen-dependent LNCaP prostate cancer cells were cultured with a matched pair of normal and cancer-associated prostate myofibroblast cells to simulate cancer-stromal interaction, and cellular changes in the co-culture were documented by tracking the red fluorescence. We found frequent spontaneous fusions between cancer and stromal cells throughout the co-culture. In colony formation assays assessing the fate of the hybrid cells, most of the cancer-stromal fusion hybrids remained growth-arrested and eventually perished. However, some of the hybrids survived to form colonies from the co-culture with cancer-associated stromal cells. These derivative clones showed genomic alterations together with androgen-independent phenotype. The results from this study reveal that prostate cancer cells are fusogenic, and cancer-stromal interaction can lead to spontaneous fusion between the two cell types. While a cancer-stromal fusion strategy may allow the stromal compartment to annihilate invading cancer cells, certain cancer-stromal hybrids with increased survival capability may escape annihilation to form a derivative cancer cell population with an altered genotype and increased malignancy. Cancer-stromal fusion thus lays a foundation for an incessant co-evolution between cancer and the cancer-associated stromal cells in the tumor microenvironment.

Identification of factors that mediate visceral and bone metastatic spread and subsequent bone remodeling events is highly relevant to successful therapeutic intervention in advanced human prostate cancer (PCa). TBX2, a T-box family transcription factor that negatively regulates cell cycle inhibitor p21, plays critical roles during embryonic development, and recent studies have highlighted its role in cancer. Here we report that TBX2 is overexpressed in human PCa specimens and bone metastases from xenograft mouse models of human PCa. Blocking endogenous TBX2 expression in PC3 and ARCaPM PCa cell models using a dominant negative construct resulted in decreased tumor cell proliferation, colony formation, and invasion in vitro. Blocking endogenous TBX2 in human PCa mouse xenografts decreased invasion and abrogation of bone and soft tissue metastasis. Furthermore, blocking endogenous TBX2 in PCa cells dramatically reduced bone colonizing capability through reduced tumor cell growth and bone remodeling in an intra-tibial mouse model. TBX2 acted in trans by promoting transcription of the canonical WNT (WNT3A) promoter. Genetically rescuing WNT3A levels in PCa cells with endogenously blocked TBX2 partially restored the TBX2-induced PCa metastatic capability in mice. Conversely, WNT3A neutralizing antibodies or WNT antagonist SFRP-2 blocked TBX2 induced invasion. Our findings highlight TBX2 as a novel therapeutic target upstream of WNT3A, where WNT3A antagonists could be novel agents for the treatment of metastasis and for skeletal complications in PCa patients.

Abnormalities in nuclear shape are a well-known feature of cancer, but their contribution to malignant progression remains poorly understood. Here, we show that depletion of the cytoskeletal regulator, Diaphanous-related formin 3 (DIAPH3), or the nuclear membrane-associated proteins, lamin A/C, in prostate and breast cancer cells, induces nuclear shape instability, with a corresponding gain in malignant properties, including secretion of extracellular vesicles that contain genomic material. This transformation is characterized by a reduction and/or mislocalization of the inner nuclear membrane protein, emerin. Consistent with this, depletion of emerin evokes nuclear shape instability and promotes metastasis. By visualizing emerin localization, evidence for nuclear shape instability was observed in cultured tumor cells, in experimental models of prostate cancer, in human prostate cancer tissues, and in circulating tumor cells from patients with metastatic disease. Quantitation of emerin mislocalization discriminated cancer from benign tissue and correlated with disease progression in a prostate cancer cohort. Taken together, these results identify emerin as a mediator of nuclear shape stability in cancer and show that destabilization of emerin can promote metastasis. This study identifies a novel mechanism integrating the control of nuclear structure with the metastatic phenotype, and our inclusion of two types of human specimens (cancer tissues and circulating tumor cells) demonstrates direct relevance to human cancer. http://cancerres.aacrjournals.org/content/canres/78/21/6086/F1.large.jpg .