Circulating exosomal mRNA profiling identifies novel signatures for the detection of prostate cancer.

The landscape and characteristics of circulating exosomal messenger RNAs (emRNAs) are poorly understood, which hampered the accurate detection of circulating emRNAs. Through comparing RNA sequencing data of circulating exosomes with the corresponding data in tissues, we illustrated the different characteristics of emRNAs compared to tissue mRNAs. We then developed an improved strategy for emRNA detection based on the features of circulating emRNAs. Using the optimized detection strategy, we further validated prostate cancer (PCa) associated emRNAs discovered by emRNA-seq in a large cohort of patients and identified emRNA signatures for PCa screening and diagnosis using logistic regression analysis. The receiver operating characteristic curve (ROC) analysis showed that the circulating emRNA-based screening signature yielded an area under the ROC curve (AUC) of 0.948 in distinguishing PCa patients from healthy controls. The circulating emRNA-based diagnostic signature also showed a great performance in predicting prostate biopsy results (AUC: 0.851). In conclusion, our study developed an optimized emRNA detection strategy and identified novel emRNA signatures for the detection of PCa.

Monoamine oxidase A inhibitor-near-infrared dye conjugate reduces prostate tumor growth.

Development of anti-cancer agents with high tumor-targeting specificity and efficacy is critical for modern multidisciplinary cancer research. Monoamine oxidase A (MAOA), a mitochondria-bound enzyme, degrades monoamine neurotransmitters and dietary monoamines. Recent evidence suggests a correlation between increased MAOA expression and prostate cancer (PCa) progression with poor outcomes for patients. MAOA induces epithelial-mesenchymal transition (EMT) and augments hypoxic effects by producing excess reactive oxygen species. Thus, development of MAOA inhibitors which selectively target tumors becomes an important goal in cancer pharmacology. Here we describe the design, synthesis, and in vitro and in vivo evaluation of NMI, a conjugate that combines a near-infrared dye for tumor targeting with the moiety derived from the MAOA inhibitor clorgyline. NMI inhibits MAOA with low micromolar IC50, suppresses PCa cell proliferation and colony formation, and reduces migration and invasion. In mouse PCa xenografts, NMI targets tumors with no detectable accumulation in normal tissues, providing effective reduction of the tumor burden. Analysis of tumor specimens shows reduction in Ki-67(+) and CD31(+) cells, suggesting a decrease of cell proliferation and angiogenesis and an increase in M30(+) cells, indicating increased apoptosis. Gene expression profiles of tumors treated with NMI demonstrate reduced expression of oncogenes FOS, JUN, NFKB, and MYC and cell cycle regulators CCND1, CCNE1, and CDK4/6, along with increases in the levels of tumor suppressor gene TP53, cell cycle inhibitors CDKN1A and CDKN2A, and MAOA-downstream genes that promote EMT, tumor hypoxia, cancer cell migration, and invasion. These data suggest that NMI exerts its effect through tumor-targeted delivery of a MAOA-inactivating group, making NMI a valuable anti-tumor agent.

Glycolytic potential enhanced by blockade of pyruvate influx into mitochondria sensitizes prostate cancer to detection and radiotherapy.

OBJECTIVE: This study aimed to evaluate the effects of mitochondrial pyruvate carrier (MPC) blockade on the sensitivity of detection and radiotherapy of prostate cancer (PCa). METHODS: We investigated glycolysis reprogramming and MPC changes in patients with PCa by using metabolic profiling, RNA-Seq, and tissue microarrays. Transient blockade of pyruvate influx into mitochondria was observed in cellular studies to detect its different effects on prostate carcinoma cells and benign prostate cells. Xenograft mouse models were injected with an MPC inhibitor to evaluate the sensitivity of 18F-fluorodeoxyglucose positron emission tomography with computed tomography and radiotherapy of PCa. Furthermore, the molecular mechanism of this different effect of transient blockage towards benign prostate cells and prostate cancer cells was studied in vitro. RESULTS: MPC was elevated in PCa tissue compared with benign prostate tissue, but decreased during cancer progression. The transient blockade increased PCa cell proliferation while decreasing benign prostate cell proliferation, thus increasing the sensitivity of PCa cells to 18F-PET/CT (SUVavg, P = 0.016; SUVmax, P = 0.03) and radiotherapy (P < 0.01). This differential effect of MPC on PCa and benign prostate cells was dependent on regulation by a VDAC1-MPC-mitochondrial homeostasis-glycolysis pathway. CONCLUSIONS: Blockade of pyruvate influx into mitochondria increased glycolysis levels in PCa but not in non-carcinoma prostate tissue. This transient blockage sensitized PCa to both detection and radiotherapy, thus indicating that glycolytic potential is a novel mechanism underlying PCa progression. The change in the mitochondrial pyruvate influx caused by transient MPC blockade provides a critical target for PCa diagnosis and treatment.

Valproic acid induces monoamine oxidase A via Akt/forkhead box O1 activation.

Valproic acid (VPA) has been widely used in clinics for the treatment of multiple neuropsychiatric disorders, such as epilepsy and bipolar disorder. One of the mechanisms by which VPA exerts its effect is through regulating the brain levels of serotonin. However, the molecular basis of this VPA action is not fully understood. Here, we report for the first time that VPA activates monoamine oxidase (MAO) A catalytic activity, mRNA level, and promoter activity. MAO A is a key enzyme that degrades a number of monoamine neurotransmitters, including serotonin. Our results show that VPA increased the phosphorylation of both Akt and Forkhead box O1 (FoxO1), whereas pretreatment of cells with 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002) (a phosphoinositide 3-kinase inhibitor) reduced the VPA activation of MAO A. Overexpression of FoxO1 dramatically repressed both the basal and VPA-induced MAO A catalytic and promoter activities to 30 to 60%. Small interfering RNA knockdown of FoxO1 attenuated the stimulating effect of VPA on MAO A. Moreover, introduction of a constitutively active form of FoxO1 abolished the activation of MAO A by VPA and Akt. These results suggest that FoxO1 is a repressor for MAO A transcription, and its phosphorylation is involved in VPA activation of MAO A. Sequence analysis, electrophoretic mobility shift and chromatin immunoprecipitation assays further showed the presence of a functional FoxO1-binding site in MAO A core promoter. Taken together, these results demonstrate that MAO A is a novel target for VPA via Akt/FoxO1 signaling pathway. This information provides new insights into the pharmacological mechanisms and therapeutic implications of VPA action.

Transcription factor E2F-associated phosphoprotein (EAPP), RAM2/CDCA7L/JPO2 (R1), and simian virus 40 promoter factor 1 (Sp1) cooperatively regulate glucocorticoid activation of monoamine oxidase B.

Glucocorticoid steroid hormones play important roles in many neurophysiological processes such as responses to stress, behavioral adaption, and mood. One mechanism by which glucocorticoids exert functions in the brain is via the modulation of neurotransmission systems. Glucocorticoids are capable of inducing the activities of monoamine oxidases (MAOs), which degrade monoamine neurotransmitters including serotonin, norepinephrine, phenylethylamine, and dopamine. However, the molecular mechanisms for such induction are not yet fully understood. Here, we report that dexamethasone, a synthetic glucocorticoid hormone, stimulates MAO B (an isoform of MAOs) promoter and catalytic activities via both the fourth glucocorticoid response element (GRE) and simian virus 40 promoter factor 1 (Sp1) binding sites in MAO B promoter. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation analysis demonstrated that glucocorticoid receptor binds to the fourth GRE in vitro and in vivo. Using Sp1-binding motifs as bait in a yeast one-hybrid system, we identified two novel transcriptional repressors of MAO B, E2F-associated phosphoprotein (EAPP) and R1 (RAM2/CDCA7L/JPO2), that down-regulate MAO B via MAO B core promoter, which contains Sp1 sites. EMSA suggested that EAPP and R1 competed with Sp1 for binding to the Sp1 site in vitro. Moreover, EAPP and R1 reduced Sp1-activated glucocorticoid activation of MAO B promoter. In response to dexamethasone, lower occupancy by EAPP and R1 and higher occupancy by Sp1 were shown at the natural MAO B core promoter. Together, this study uncovers for the first time the molecular mechanisms for glucocorticoid activation of MAO B gene and provides new insights into the hormonal regulation of MAO.

Transcriptional regulation and multiple functions of MAO genes.

Monoamine oxidase (MAO) A and MAO B are a crucial pair of isoenzymes, which oxidatively deaminate monoamine neurotransmitters and dietary amines with a production of hydrogen peroxide. These two isoenzymes have different but overlapping substrate and inhibitor specificities. MAO A and MAO B share 70% amino acid sequence identity and show different temporal and spatial expressions in both humans and mice. Abnormal MAO A or MAO B activity has been implicated in numerous neurological and psychiatric disorders. A better understanding of the transcriptional regulation of MAO A and MAO B genes may help explain the differential tissue-specific expression of these two isoenzymes and provide insights into the molecular basis of the disorders associated with MAO dysfunction. This review discusses the recent progress in the transcriptional regulation and multiple functions of MAO A and MAO B genes.

KDM6B is an androgen regulated gene and plays oncogenic roles by demethylating H3K27me3 at cyclin D1 promoter in prostate cancer.

Lysine (K)-specific demethylase 6B (KDM6B), a stress-inducible H3K27me3 demethylase, plays oncogenic or antitumoral roles in malignant tumors depending on the type of tumor cell. However, how this histone modifier affects the progression of prostate cancer (PCa) is still unknown. Here we analyzed sequenced gene expression data and tissue microarray to explore the expression features and prognostic value of KDM6B in PCa. Further, we performed in vitro cell biological experiments and in vivo nude mouse models to reveal the biological function, upstream and downstream regulation mechanism of KDM6B. In addition, we investigated the effects of a KDM6B inhibitor, GSK-J4, on PCa cells. We showed that KDM6B overexpression was observed in PCa, and elevated KDM6B expression was associated with high Gleason Score, low serum prostate-specific antigen level and shorted recurrence-free survival. Moreover, KDM6B prompted proliferation, migration, invasion and cell cycle progression and suppressed apoptosis in PCa cells. GSK-J4 administration could significantly suppress the biological function of KDM6B in PCa cells. KDM6B is involved in the development of castration-resistant prostate cancer (CRPC), and combination of MDV3100 plus GSK-J4 is effective for CRPC and MDV3100-resistant CRPC. Mechanism exploration revealed that androgen receptor can decrease the transcription of KDM6B and that KDM6B demethylates H3K27me3 at the cyclin D1 promoter and cooperates with smad2/3 to prompt the expression of cyclin D1. In conclusion, our study demonstrates that KDM6B is an androgen receptor regulated gene and plays oncogenic roles by promoting cyclin D1 transcription in PCa and GSK-J4 has the potential to be a promising agent for the treatment of PCa.

Regulatory signaling network in the tumor microenvironment of prostate cancer bone and visceral organ metastases and the development of novel therapeutics.

This article describes cell signaling network of metastatic prostate cancer (PCa) to bone and visceral organs in the context of tumor microenvironment and for the development of novel therapeutics. The article focuses on our recent progress in the understanding of: 1) The plasticity and dynamics of tumor-stroma interaction; 2) The significance of epigenetic reprogramming in conferring cancer growth, invasion and metastasis; 3) New insights on altered junctional communication affecting PCa bone and brain metastases; 4) Novel strategies to overcome therapeutic resistance to hormonal antagonists and chemotherapy; 5) Genetic-based therapy to co-target tumor and bone stroma; 6) PCa-bone-immune cell interaction and TBX2-WNTprotein signaling in bone metastasis; 7) The roles of monoamine oxidase and reactive oxygen species in PCa growth and bone metastasis; and 8) Characterization of imprinting cluster of microRNA, in tumor-stroma interaction. This article provides new approaches and insights of PCa metastases with emphasis on basic science and potential for clinical translation. This article referenced the details of the various approaches and discoveries described herein in peer-reviewed publications. We dedicate this article in our fond memory of Dr. Donald S. Coffey who taught us the spirit of sharing and the importance of focusing basic science discoveries toward translational medicine.

Loss of MAOA in epithelia inhibits adenocarcinoma development, cell proliferation and cancer stem cells in prostate.

Monoamine oxidase A (MAOA) is a mitochondrial enzyme, which degrades monoamine neurotransmitters and dietary amines and produces H2O2. Recent studies have shown increased MAOA expression in prostate cancer (PCa), glioma, and classical Hodgkin lymphoma. However, the biological function of MAOA in cancer development remains unknown. In this study, we investigated the role of MAOA in the development of prostate adenocarcinoma by creating a prostate-specific Pten/MAOA knockout (KO) mouse model, in which MAOA-floxP mouse was crossed with the conditional Pten KO PCa mouse that develops invasive PCa. In contrast to Pten KO mice, age-matched Pten/MAOA KO mice exhibited a significant decrease in both prostate size and the incidence of invasive cancer. We observed a significant decline in AKT phosphorylation and Ki67 expression in Pten/MAOA KO mice, which reduced epithelial cell growth and proliferation. As cancer stem cells (CSCs) are required for tumor initiation and growth, we investigated expression of OCT4 and NANOG in the setting of decreased MAOA expression. We found that both OCT4 and NANOG were significantly attenuated in the prostate epithelia of Pten/MAOA KO mice compared to Pten KO mice, which was confirmed with targeted knockdown of MAOA with a short-hairpin(sh) vector targeting MAOA compared to cells transfected with a control vector. Expression of other markers associated with the a stem cell phenotype, including CD44, α2ß1, and CD133 as well as HIF-1α+CD44+ stem cells were all decreased in shMAOA PCa cells compared with empty vector-transfected control cells. We also found spheroid formation ability in PCa cells was decreased when endogenous MAOA was suppressed by siRNA or MAOA inhibitor clorgyline in a colony formation assay. Using the TCGA database, elevated MAOA expression was associated with reduced Pten levels in high Gleason grade in patient samples. Further, we found that Pten-positive PCa cells were more resistant to clorgyline treatments than Pten-null cells in tumorigenicity and stemness. Taken together, these studies suggest that MAOA expression promotes PCa development by increasing cell proliferation and CSCs and highlights the potential use of MAOA inhibitors for the treatment of PCa.

Whole-genome and Transcriptome Sequencing of Prostate Cancer Identify New Genetic Alterations Driving Disease Progression.

BACKGROUND: Global disparities in prostate cancer (PCa) incidence highlight the urgent need to identify genomic abnormalities in prostate tumors in different ethnic populations including Asian men. OBJECTIVE: To systematically explore the genomic complexity and define disease-driven genetic alterations in PCa. DESIGN, SETTING, AND PARTICIPANTS: The study sequenced whole-genome and transcriptome of tumor-benign paired tissues from 65 treatment-naive Chinese PCa patients. Subsequent targeted deep sequencing of 293 PCa-relevant genes was performed in another cohort of 145 prostate tumors. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The genomic alteration landscape in PCa was analyzed using an integrated computational pipeline. Relationships with PCa progression and survival were analyzed using nonparametric test, log-rank, and multivariable Cox regression analyses. RESULTS AND LIMITATIONS: We demonstrated an association of high frequency of CHD1 deletion with a low rate of TMPRSS2-ERG fusion and relatively high percentage of mutations in androgen receptor upstream activator genes in Chinese patients. We identified five putative clustered deleted tumor suppressor genes and provided experimental and clinical evidence that PCDH9, deleted/loss in approximately 23% of tumors, functions as a novel tumor suppressor gene with prognostic potential in PCa. Furthermore, axon guidance pathway genes were frequently deregulated, including gain/amplification of PLXNA1 gene in approximately 17% of tumors. Functional and clinical data analyses showed that increased expression of PLXNA1 promoted prostate tumor growth and independently predicted prostate tumor biochemical recurrence, metastasis, and poor survival in multi-institutional cohorts of patients with PCa. A limitation of this study is that other genetic alterations were not experimentally investigated. CONCLUSIONS: There are shared and salient genetic characteristics of PCa in Chinese and Caucasian men. Novel genetic alterations in PCDH9 and PLXNA1 were associated with disease progression. PATIENT SUMMARY: We reported the first large-scale and comprehensive genomic data of prostate cancer from Asian population. Identification of these genetic alterations may help advance prostate cancer diagnosis, prognosis, and treatment.

MAOA-Dependent Activation of Shh-IL6-RANKL Signaling Network Promotes Prostate Cancer Metastasis by Engaging Tumor-Stromal Cell Interactions.

Metastasis is a predominant cause of death for prostate cancer (PCa) patients; however, the underlying mechanisms are poorly understood. We report that monoamine oxidase A (MAOA) is a clinically and functionally important mediator of PCa bone and visceral metastases, activating paracrine Shh signaling in tumor-stromal interactions. MAOA provides tumor cell growth advantages in the bone microenvironment by stimulating interleukin-6 (IL6) release from osteoblasts, and triggers skeletal colonization by activating osteoclastogenesis through osteoblast production of RANKL and IL6. MAOA inhibitor treatment effectively reduces metastasis and prolongs mouse survival by disengaging the Shh-IL6-RANKL signaling network in stromal cells in the tumor microenvironment. These findings provide a rationale for targeting MAOA and its associated molecules to treat PCa metastasis.

Review on near-infrared heptamethine cyanine dyes as theranostic agents for tumor imaging, targeting, and photodynamic therapy.

A class of near-infrared fluorescence (NIRF) heptamethine cyanine dyes that are taken up and accumulated specifically in cancer cells without chemical conjugation have recently emerged as promising tools for tumor imaging and targeting. In addition to their fluorescence and nuclear imaging-based tumor-imaging properties, these dyes can be developed as drug carriers to safely deliver chemotherapy drugs to tumors. They can also be used as effective agents for photodynamic therapy with remarkable tumoricidal activity via photodependent cytotoxic activity. The preferential uptake of dyes into cancer but not normal cells is co-operatively mediated by the prevailing activation of a group of organic anion-transporting polypeptides on cancer cell membranes, as well as tumor hypoxia and increased mitochondrial membrane potential in cancer cells. Such mechanistic explorations have greatly advanced the current application and future development of NIRF dyes and their derivatives as anticancer theranostic agents. This review summarizes current knowledge and emerging advances in NIRF dyes, including molecular characterization, photophysical properties, multimodal development and uptake mechanisms, and their growing potential for preclinical and clinical use.

Optical imaging of gastric cancer with near-infrared heptamethine carbocyanine fluorescence dyes.

Near-infrared fluorescence (NIRF) imaging agents are promising tools for noninvasive cancer imaging. Here, we explored the tumor-specific targeting ability of NIRF heptamethine carbocyanine MHI-148 dye in cultured gastric cancer cells, gastric cancer cell-derived and patient-derived tumor xenograft (PDX) models. We show that the NIRF dye specifically accumulated in tumor regions of both xenograft models, suggesting the potential utility of the dye for tumor-specific imaging and targeting in gastric cancer. We also demonstrated significant correlations between NIRF signal intensity and tumor volume in PDX models. Mechanistically, the higher cellular uptake of MHI-148 in gastric cancer cells than in normal cells was stimulated by hypoxia and activation of a group of organic anion-transporting polypeptide (OATP) genes. Importantly, this NIRF dye was not retained in inflammatory stomach tissues induced by gastric ulcer in mice. In addition, fresh clinical gastric tumor specimens, when perfused with NIR dye, exhibited increased uptake of NIR dye in situ. Together, these results show the possibility of using NIRF dyes as novel candidate agents for clinical imaging and detection of gastric cancer.

SREBP-2 promotes stem cell-like properties and metastasis by transcriptional activation of c-Myc in prostate cancer.

Sterol regulatory element-binding protein-2 (SREBP-2) transcription factor mainly controls cholesterol biosynthesis and homeostasis in normal cells. The role of SREBP-2 in lethal prostate cancer (PCa) progression remains to be elucidated. Here, we showed that expression of SREBP-2 was elevated in advanced pathologic grade and metastatic PCa and significantly associated with poor clinical outcomes. Biofunctional analyses demonstrated that SREBP-2 induced PCa cell proliferation, invasion and migration. Furthermore, overexpression of SREBP-2 increased the PCa stem cell population, prostasphere-forming ability and tumor-initiating capability, whereas genetic silencing of SREBP-2 inhibited PCa cell growth, stemness, and xenograft tumor growth and metastasis. Clinical and mechanistic data showed that SREBP-2 was positively correlated with c-Myc and induced c-Myc activation by directly interacting with an SREBP-2-binding element in the 5'-flanking c-Myc promoter region to drive stemness and metastasis. Collectively, these clinical and experimental results reveal a novel role of SREBP-2 in the induction of a stem cell-like phenotype and PCa metastasis, which sheds light on translational potential by targeting SREBP-2 as a promising therapeutic approach in PCa.

Combined cell surface carbonic anhydrase 9 and CD147 antigens enable high-efficiency capture of circulating tumor cells in clear cell renal cell carcinoma patients.

Circulating tumor cells (CTCs) have emerged as promising tools for noninvasive cancer detection and prognosis. Most conventional approaches for capturing CTCs use an EpCAM-based enrichment strategy, which does not work well in cancers that show low or no expression of EpCAM, such as renal cell carcinoma (RCC). In this study, we developed a new set of cell surface markers including CA9 and CD147 as alternative CTC-capture antigens specifically designed for RCC patients. We showed that the expression of both CA9 and CD147 was prevalent in a RCC patient cohort (n=70) by immunohistochemical analysis, with both molecules in combination covering 97.1% of cases. The NanoVelcro platform combined with CA9-/CD147-capture antibodies demonstrated significantly higher efficiency for capturing both CTC-mimicking renal cancer cells and RCC CTCs in peripheral blood, compared to the conventional EpCAM-based method. Using immunofluorescence cytological validation at the single-cell level, we were able to identify bona fide CTCs in RCC patient blood following the well-accepted criteria in our CTC-capture system. We further demonstrated a significant association of CTC numbers as well as the CTC expression status of Vimentin, a mesenchymal marker, with disease progression, including pathologic features and clinical staging. These results provide new insights into developing novel, effective targets/approaches for capturing CTCs, making CTCs a valuable tool for improved cancer detection, prognosis and treatment in RCC.

Anti-cancer efficacy of SREBP inhibitor, alone or in combination with docetaxel, in prostate cancer harboring p53 mutations.

Mutant p53 proteins (mutant p53s) have oncogenic gain-of-function properties correlated with tumor grade, castration resistance, and prostate cancer (PCa) tumor recurrence. Docetaxel is a standard first-line treatment for metastatic castration-resistant PCa (mCRPC) after the failure of hormone therapy. However, most mCRPC patients who receive docetaxel experience only transient benefits and rapidly develop incurable drug resistance, which is closely correlated with the p53 mutation status. Mutant p53s were recently reported to regulate the metabolic pathways via sterol regulatory element-binding proteins (SREBPs). Therefore, targeting the SREBP metabolic pathways with docetaxel as a combination therapy may offer a potential strategy to improve anti-tumor efficacy and delay cellular drug resistance in mCRPC harboring mutant p53s. Our previous data showed that fatostatin, a new SREBP inhibitor, inhibited cell proliferation and induced apoptosis in androgen receptor (AR)-positive PCa cell lines and xenograft mouse models. In this study, we demonstrated that mutant p53s activate the SREBP-mediated metabolic pathways in metastatic AR-negative PCa cells carrying mutant p53s. By blocking the SREBP pathways, fatostatin inhibited cell growth and induced apoptosis in metastatic AR-negative PCa cells harboring mutant p53s. Furthermore, the combination of fatostatin and docetaxel resulted in greater proliferation inhibition and apoptosis induction compared with single agent treatment in PCa cells in vitro and in vivo, especially those with mutant p53s. These data suggest for the first time that fatostatin alone or in combination with docetaxel could be exploited as a novel and promising therapy for metastatic PCa harboring p53 mutations.

Near-infrared fluorescence heptamethine carbocyanine dyes mediate imaging and targeted drug delivery for human brain tumor.

Brain tumors and brain metastases are among the deadliest malignancies of all human cancers, largely due to the cellular blood-brain and blood-tumor barriers that limit the delivery of imaging and therapeutic agents from the systemic circulation to tumors. Thus, improved strategies for brain tumor visualization and targeted treatment are critically needed. Here we identified and synthesized a group of near-infrared fluorescence (NIRF) heptamethine carbocyanine dyes and derivative NIRF dye-drug conjugates for effective imaging and therapeutic targeting of brain tumors of either primary or metastatic origin in mice, which is mechanistically mediated by tumor hypoxia and organic anion-transporting polypeptide genes. We also demonstrate that these dyes, when conjugated to chemotherapeutic agents such as gemcitabine, significantly restricted the growth of both intracranial glioma xenografts and prostate tumor brain metastases and prolonged survival in mice. These results show promise in the application of NIRF dyes as novel theranostic agents for the detection and treatment of brain tumors.

Heptamethine carbocyanine dye-mediated near-infrared imaging of canine and human cancers through the HIF-1α/OATPs signaling axis.

Near-infrared (NIR) fluorescence imaging agents are promising tools for noninvasive cancer imaging. This study explored the specific uptake and retention of a NIR heptamethine carbocyanine MHI-148 dye by canine cancer cells and tissues and human prostate cancer (PCa) specimens and also the dye uptake mechanisms. The accumulation of MHI-148 was detected specifically in canine cancer cells and tissues and freshly harvested human PCa tissues xenografted in mice by NIR fluorescence microscopy and whole-body NIR optical imaging. Specific dye uptake in canine spontaneous tumors was further confirmed by PET imaging. Higher hypoxia-inducible factor-1α (HIF-1α) and organic anion-transporting polypeptide (OATP) protein and mRNA expression was demonstrated by multiplex quantum dots labeling and qPCR in tumors over that of normal tissues. Treating cancer cells with HIF-1α stabilizers activated HIF-1α downstream target genes, induced OATP superfamily gene expression and enhanced cellular uptake and retention of NIR dyes. Moreover, silencing HIF-1α by siRNA significantly decreased OATP mRNA expression and blocked NIR dye uptake in cancer cells. Together, these results demonstrated the preferential uptake of NIR dyes by canine and human cancer cells and tissues via the HIF-1α/OATPs signaling axis, which provides insights into future application of these dyes for cancer detection and treatment.

Near-infrared fluorescence imaging of cancer mediated by tumor hypoxia and HIF1α/OATPs signaling axis.

Near-infrared fluorescence (NIRF) imaging agents are promising tools for noninvasive cancer imaging. Here, we explored the mechanistic properties of a specific group of NIR heptamethine carbocyanines including MHI-148 dye we identified and synthesized, and demonstrated these dyes to achieve cancer-specific imaging and targeting via a hypoxia-mediated mechanism. We found that cancer cells and tumor xenografts exhibited hypoxia-dependent MHI-148 dye uptake in vitro and in vivo, which was directly mediated by hypoxia-inducible factor 1α (HIF1α). Microarray analysis and dye uptake assay further revealed a group of hypoxia-inducible organic anion-transporting polypeptides (OATPs) responsible for dye uptake, and the correlation between OATPs and HIF1α was manifested in progressive clinical cancer specimens. Finally, we demonstrated increased uptake of MHI-148 dye in situ in perfused clinical tumor samples with activated HIF1α/OATPs signaling. Our results establish these NIRF dyes as potential tumor hypoxia-dependent cancer-targeting agents and provide a mechanistic rationale for continued development of NIRF imaging agents for improved cancer detection, prognosis and therapy.

Monoamine oxidase A mediates prostate tumorigenesis and cancer metastasis.

Tumors from patients with high-grade aggressive prostate cancer (PCa) exhibit increased expression of monoamine oxidase A (MAOA), a mitochondrial enzyme that degrades monoamine neurotransmitters and dietary amines. Despite the association between MAOA and aggressive PCa, it is unclear how MAOA promotes PCa progression. Here, we found that MAOA functions to induce epithelial-to-mesenchymal transition (EMT) and stabilize the transcription factor HIF1α, which mediates hypoxia through an elevation of ROS, thus enhancing growth, invasiveness, and metastasis of PCa cells. Knockdown and overexpression of MAOA in human PCa cell lines indicated that MAOA induces EMT through activation of VEGF and its coreceptor neuropilin-1. MAOA-dependent activation of neuropilin-1 promoted AKT/FOXO1/TWIST1 signaling, allowing FOXO1 binding at the TWIST1 promoter. Importantly, the MAOA-dependent HIF1α/VEGF-A/FOXO1/TWIST1 pathway was activated in high-grade PCa specimens, and knockdown of MAOA reduced or even eliminated prostate tumor growth and metastasis in PCa xenograft mouse models. Pharmacological inhibition of MAOA activity also reduced PCa xenograft growth in mice. Moreover, high MAOA expression in PCa tissues correlated with worse clinical outcomes in PCa patients. These findings collectively characterize the contribution of MAOA in PCa pathogenesis and suggest that MAOA has potential as a therapeutic target in PCa.