Exosomal miR-664a-5p as a therapeutic target biomarker for PARP inhibitor response in prostate cancer.

This study investigated the role of urinary exosomal miR-664a-5p as a potential therapeutic target in prostate cancer (PCa). Small RNA sequencing of urinary exosomes from PCa patients with different responses to PARP inhibitors revealed that miR-664a-5p was significantly upregulated in responsive patients. Overexpression of miR-664a-5p enhanced the sensitivity of PCa cells to PARP inhibitors by directly targeting FOXM1, a transcription factor involved in DNA damage repair, leading to the downregulation of DNA damage response genes. Combined treatment with miR-664a-5p and olaparib synergistically inhibited tumor growth in a PC-3 xenograft mouse model. These findings suggest that urinary exosomal miR-664a-5p is a potential therapeutic biomarker for PARP inhibitor response in PCa patients, and targeting FOXM1 via miR-664a-5p represents a promising strategy for enhancing PARP inhibitor efficacy in PCa treatment.

Integrated Bioinformatics Analysis Identified ASNS and DDIT3 as the Therapeutic Target in Castrate-Resistant Prostate Cancer.

Many studies have demonstrated the mechanisms of progression to castration-resistant prostate cancer (CRPC) and novel strategies for its treatment. Despite these advances, the molecular mechanisms underlying the progression to CRPC remain unclear, and currently, no effective treatments for CRPC are available. Here, we characterized the key genes involved in CRPC progression to gain insight into potential therapeutic targets. Bicalutamide-resistant prostate cancer cells derived from LNCaP were generated and named Bical R. RNA sequencing was used to identify differentially expressed genes (DEGs) between LNCaP and Bical R. In total, 631 DEGs (302 upregulated genes and 329 downregulated genes) were identified. The Cytohubba plug-in in Cytoscape was used to identify seven hub genes (ASNS, AGT, ATF3, ATF4, DDIT3, EFNA5, and VEGFA) associated with CRPC progression. Among these hub genes, ASNS and DDIT3 were markedly upregulated in CRPC cell lines and CRPC patient samples. The patients with high expression of ASNS and DDIT3 showed worse disease-free survival in patients with The Cancer Genome Atlas (TCGA)-prostate adenocarcinoma (PRAD) datasets. Our study revealed a potential association between ASNS and DDIT3 and the progression to CRPC. These results may contribute to the development of potential therapeutic targets and mechanisms underlying CRPC progression, aiming to improve clinical efficacy in CRPC treatment.

DNA methylation biomarkers distinguishing early-stage prostate cancer from benign prostatic hyperplasia.

Background: DNA methylation markers are considered robust diagnostic features in various cancer types, as epigenetic marks are commonly altered during cancer progression. Differentiation between benign prostatic hyperplasia (BPH) and early-stage prostate cancer (PCa) is clinically difficult, relying on the information of the patient's symptoms or levels of prostate-specific antigen. Methods: A total of 42 PCa patients and 11 BPH patients were recruited. Genomic DNA was purified from tissues and used for the library preparation of the target-enriched methylome with enzymatic conversion and a Twist 85 Mbp EM-seq panel. Paired-end sequencing (150 bp) was performed using NovaSeq 6000 or NextSeq 550. After quality control, including adapter trimming and de-duplication of raw sequencing data, differential methylation patterns were analyzed between the BPH and PCa groups. Results: We report DNA methylation patterns existing between BPH and PCa. The major finding is that broad hypermethylation occurred at genic loci in PCa tissues as compared to the BPH. Gene ontology analysis suggested that hypermethylation of genic loci involved in chromatin and transcriptional regulation is involved in cancer progression. We also compared PCa tissues with high Gleason scores to tissues with low Gleason scores. The high-Gleason PCa tissues showed hundreds of focal differentially methylated CpG sites corresponding to genes functioning in cancer cell proliferation or metastasis. This suggests that dissecting early-to-advanced-grade cancer stages requires an in-depth analysis of differential methylation at the single CpG site level. Conclusions: Our study reports that enzymatic methylome sequencing data can be used to distinguish PCa from BPH and advanced PCa from early-stage PCa. The stage-specific methylation patterns in this study will be valuable resources for diagnostic purposes as well as further development of liquid biopsy approaches for the early detection of PCa.

Erectile Dysfunction Treatment Using Stem Cell Delivery Patch in a Cavernous Nerve Injury Rat Model.

Erectile dysfunction (ED) is a common and feared complication of radical prostatectomy (RP) for prostate cancer. Recently, tissue engineering for post-prostatectomy ED has been attempted in which controlled interactions between cells, growth factors, and the extracellular matrix (ECM) are important for the structural integrity if nerve regeneration. In this study, we evaluated the effects of a biomechanical ECM patch on the morphology and behavior of human bone marrow-derived mesenchymal stem cells (hBMSCs) in a bilateral cavernous nerve injury (BCNI) rat model. The ECM patch, made of decellularized human fibroblast-derived ECM (hFDM) and a biocompatible polyvinyl alcohol (PVA) hydrogel, was tested with human bone marrow-derived mesenchymal stem cells (hBMSCs) on a bilateral cavernous nerve injury (BCNI) rat model. In vitro analysis showed that the hFDM/PVA + hBMSCs patches significantly increased neural development markers. In vivo experiments demonstrated that the rats treated with the hFDM/PVA patch had higher ICP/MAP ratios, higher ratios of smooth muscle to collagen, increased nNOS content, higher levels of eNOS protein expression, and higher cGMP levels compared to the BCNI group. These results indicate that the hFDM/PVA patch is effective in promoting angiogenesis, smooth muscle regeneration, and nitrergic nerve regeneration, which could contribute to improved erectile function in post-prostatectomy ED.

Niclosamide exerts anticancer effects through inhibition of the FOXM1-mediated DNA damage response in prostate cancer.

Niclosamide, an established anti-helminthic drug, has anticancer activity against various cancers including prostate cancer, but the underlying mechanisms have not yet been defined. We demonstrated the anticancer effects of niclosamide in castration-resistant prostate cancer (CRPC) cells, and elucidated the mechanism of action of niclosamide in CRPC. Niclosamide reduced cell proliferation and induced apoptosis of CRPC cells in vitro, and also reduced xenograft tumor growth in vivo. Niclosamide significantly increased the number of γH2AX- and 53BP1-positive cells. In RNA-sequencing, niclosamide induced extensive changes in gene expression including cell division, DNA replication, and DNA repair. Bioinformatics analysis using TCGA data set revealed that FOXM1 is an important target of niclosamide. In microarray assays, FOXM1 knockdown significantly inhibited several genes involved in DNA repair, and homologous recombination, in particular. Finally, FOXM1 strongly bound to EXO1 in CRPC cells, and FOXM1 knockdown significantly reduced EXO1-driven luciferase activity. Taken together, our results suggest that niclosamide exerts anticancer activity through inhibition of the FOXM1-mediated DNA damage response in CRPC.

HMGB1 promotes tumor progression and invasion through HMGB1/TNFR1/NF-κB axis in castration-resistant prostate cancer.

Prostate cancer (PCa) is the most common male cancer. Most patients treated with androgen deprivation therapy progress to castration-resistant PCa. To overcome the limitations of this treatment, there is an urgent need to identify more effective treatment targets. High mobility group box 1 protein (HMGB1) is known to be associated with progression, metastasis, and poor prognosis of several solid tumors; however, its role in PCa remains unclear. Thus, we aimed to evaluate the clinical significance and biological roles and mechanism of HMGB1 in PCa. We showed that increased expression of HMGB1 correlated with increased risk of aggressive PCa, and high expression of HMGB1 was associated with poor biochemical recurrence-free survival in a Korean cohort. Additionally, the inhibition of HMGB1 expression significantly reduced cell proliferation, invasive capacity, and NF-κB signaling in vitro. Our results indicated that HMGB1 is a critical factor in the development and progression of PCa. Moreover, we found that HMGB1 directly interacts with TNFR1, and TNFR1 overexpression in HMGB1 knockdown cells reversed the effects of HMGB1 knockdown. Importantly, our results suggest that HMGB1 binding to TNFR1 promotes tumor progression by activating the NF-κB signaling pathway in PCa; therefore, the HMGB1/TNFR1/NF-κB signaling pathway could serve as a novel therapeutic target for improving PCa therapy.

Urinary exosome microRNA signatures as a noninvasive prognostic biomarker for prostate cancer.

Predicting the risk of metastasis before starting prostate cancer (PCa) treatment can minimize the overtreatment of indolent cases and help choosing appropriate treatment. The levels of circulating microRNAs (miRNAs) from body fluids can be used as noninvasive prognostic biomarkers. In this study, urinary exosomal miRNA expression profiles of 149 PCas were determined and the miRNAs associated with metastasis were identified: miR-21, miR-16, miR-142-3p, miR-451, and miR-636. When evaluating clinical factors together, miR-21, miR-451, miR-636, and preoperative prostate-specific antigen (PSA) level remained significant in the multivariate analysis. Based on them, we developed a "Prostate Cancer Metastasis Risk Scoring (PCa-MRS)" model. The PCa-MRS showed superior stratification power (AUC = 0.925) to preoperative PSA or clinical Gleason score. Patients with high scores showed significantly poorer biochemical recurrence-free survival than those with low scores (P = 6.53 × 10-10). Our results showed the potential of urinary exosomal miRNAs as noninvasive markers for predicting metastasis and prognosis in PCa patients.

Urinary exosomal microRNA profiling in intermediate-risk prostate cancer.

MicroRNAs (miRNAs) of urine exosomes have emerged as biomarkers for urological cancers, owing to their high stability. MiRNAs have been linked to factors associated with aggressive prostate cancer such as biochemical recurrence (BCR) and metastasis. In this study, we aimed to identify urinary exosomal miRNAs as prognostic markers associated with BCR in intermediate-risk prostate cancer. We profiled the expression levels of miRNAs via next generation sequencing in urinary exosomes from 21 non-BCR patients and 6 BCR patients of intermediate-risk prostate cancer. A total of 21 urinary exosomal miRNAs were found to be differentially expressed (> twofold) in BCR patients compared to non-BCR patients. For external validation, we validated these results using quantitative reverse transcription PCR in an independent cohort of 28 non-BCR patients and 26 BCR patients. A validation analysis revealed that three miRNAs (miR-26a-5p, miR-532-5p, and miR-99b-3p) were upregulated in exosomes from BCR patients. The univariate and multivariate Cox regression analyses showed that miR-532-5p was an important predictive factor for BCR of intermediate-risk prostate cancer. In conclusion, miR-532-5p in urine exosomes might be a potential biomarker for predicting BCR, which is a poor prognosis in patients with intermediate-risk prostate cancer. Further research is needed on the biological functions and mechanisms of this miRNA.

Stem Cell/Oxygen-Releasing Microparticle Enhances Erectile Function in a Cavernous Nerve Injury Model.

Erectile dysfunction caused by damage to the cavernous nerve is a common complication of radical prostatectomy for patients with localized prostate cancer. Various studies have investigated repair of damaged tissue and prevention of fibrosis in the corpus cavernosum using stem cell therapy. However, stem cell therapy has limitations, including insufficient nutrient and oxygen supply to transplanted stem cells. This study investigated whether stem cell/oxygen-releasing hollow microparticles (HPs) had therapeutic effect on erectile dysfunction in a rat model of bilateral cavernous nerve injury (BCNI). Therapeutic effects were observed in the BCNI model at 1, 2, and 4 weeks postcavernous nerve injury. Erectile function further improved after treatment with stem cell/oxygen-releasing HP system compared with treatment with only stem cells at 4 weeks. Stem cell/oxygen-releasing HP system increased cyclic guanosine monophosphate (cGMP) level and neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase (eNOS), α-smooth muscle actin (α-SMA), and muscarinic acetylcholine receptor 3 (M3) expression while decreasing fibrosis and apoptosis in the corpus cavernosum. Our results clearly show that stem cell survival increases around transplanted stem cell/oxygen-releasing hybrid system site. Taken together, an oxygen-releasing HP system supported prolonged stem cell survival, sustaining the paracrine effect of the stem cells, and consequently enhancing erectile function. These findings show promise with regard to prolonged stem cell survival in stem cell applications for various diseases and types of tissue damage. Impact statement In this study, we used an oxygen-releasing hollow microparticles (HPs) system with stem cells to attempt to overcome certain limitations of stem cell therapy, including insufficient nutrient and oxygen supplies for transplanted stem cells. Our results demonstrated that a stem cell/oxygen-releasing HP hybrid system could further improve erectile function, cyclic guanosine monophosphate (cGMP) level, and NOS level in a bilateral cavernous nerve injury rat model through prolonged stem cell survival. Our data suggest that a stem cell/oxygen-releasing HP system is a promising clinical treatment option for postprostatectomy erectile dysfunction. Furthermore, this system may be relevant in different disease therapies and regenerative medicine.

GV1001 inhibits cell viability and induces apoptosis in castration-resistant prostate cancer cells through the AKT/NF-κB/VEGF pathway.

Purpose: We examined the effect of GV1001 in castration castration-resistant prostate cancer (CRPC) cell growth and invasion and explored the potential molecular mechanisms of action. Materials and Methods: The in vitro anti-cancer effects of GV1001 in CRPC cells were examined using cell viability assay, TUNEL assay, and flow cytometry analysis. To evaluate the effects of GV1001 on different steps of angiogenesis, wound healing assay, transwell invasion assay, endothelial cell tube formation assay, and western blot analysis were performed. Finally, the anti-cancer effects of GV1001 on tumor growth in vivo were examined in a CRPC xenograft model. Results: GV1001 inhibited cell viability and induced apoptosis in CRPC cells in vitro, accompanied by down-regulation of Bcl-2 and caspase-3. GV1001 also inhibited different steps of angiogenesis, such as migration, invasion, and endothelial tube formation, along with decreased expression of MMP-2, MMP-9, and CD31 and increased expression of TIMP-1 and TIMP-2. Mechanistically, GV1001 significantly decreased the levels of phosphorylated AKT, phosphorylated p65, and VEGF in CRPC cells in a dose-dependent manner. GV1001 was effective in suppressing tumor growth and inducing apoptosis in a CRPC xenograft mouse model. Conclusions: Our data demonstrated that GV1001 inhibited cell viability, induced apoptosis, and inhibited angiogenesis in CRPC cells by inhibition of the AKT/NF-κB/VEGF signaling pathway.

High FOXM1 expression is a prognostic marker for poor clinical outcomes in prostate cancer.

Purpose: We aimed to investigate the expression of FOXM1 and to determine the relationships between FOXM1 expression and clinicopathologic characteristics in patients with PCa. Furthermore, we reconfirmed the prognostic impact of FOXM1 in different cohorts using already published data. Patients and Methods: Formalin-fixed, paraffin-embedded tissues were collected from patients with low- (n=17), intermediate- (n=36), and high-risk (n=29) disease, from patients with CRPC (n=2) and from patients with BPH (n=28). To analyze FOXM1 expression, we performed IHC analyses. Also, we analyzed gene expression data from cBioPortal to evaluate the associations between FOXM1 alteration and prognosis of PCa. Results: FOXM1 expression measured using Allred score differed between patients with BPH, and low-, intermediate-, and high-risk PCa (0.3, 1.5, 4.8, and 6.2, respectively; p<0.001). Patients with high FOXM1 expression had higher preoperative PSA levels (p=0.023), more advanced tumor stages (p=0.047), and higher pathologic Gleason score (p<0.001) than those with low FOXM1 expression. ROC curve analysis indicated that FOXM1 expression was a useful marker for discriminating PCa from BPH (AUC 0.851, 95% CI 0.783-0.920) and for discriminating high-risk PCa from low- and intermediate-risk PCa (AUC 0.807, 95% CI 0.719-0.894). In multivariate analyses, high FOXM1 expression was an independent predictor of BCR. Finally, in the TCGA dataset, FOXM1 alteration was associated with poor overall (p=4.521e-4) and disease-free survival (p=0.0108). Conclusions: In patients with PCa, high FOXM1 expression was associated with advanced tumor stages, high Gleason score, and poor prognosis. These data suggest a role of FOXM1 in biologically and clinically aggressive PCa.

Graphene oxide-quenching-based fluorescence in situ hybridization (G-FISH) to detect RNA in tissue: Simple and fast tissue RNA diagnostics.

FISH-based RNA detection in paraffin-embedded tissue can be challenging, with complicated procedures producing uncertain results and poor image quality. Here, we developed a robust RNA detection method based on graphene oxide (GO) quenching and recovery of fluorescence in situ hybridization (G-FISH) in formalin-fixed paraffin-embedded (FFPE) tissues. Using a fluorophore-labeled peptide nucleic acid (PNA) attached to GO, the endogenous long noncoding RNA BC1, the constitutive protein ß-actin mRNA, and miR-124a and miR-21 could be detected in the cytoplasm of a normal mouse brain, primary cultured hippocampal neurons, an Alzheimer's disease model mouse brain, and glioblastoma multiforme tumor tissues, respectively. Coding and non-coding RNAs, either long or short, could be detected in deparaffinized FFPE or frozen tissues, as well as in clear lipid-exchanged anatomically rigid imaging/immunostaining-compatible tissue hydrogel (CLARITY)-transparent brain tissues. The fluorescence recovered by G-FISH correlated highly with the amount of miR-21, as measured by quantitative real time RT-PCR. We propose G-FISH as a simple, fast, inexpensive, and sensitive method for RNA detection, with a very low background, which could be applied to a variety of research or diagnostic purposes.

Therapeutic Effect of Controlled Release of Dual Growth Factor Using Heparin-Pluronic Hydrogel/Gelatin-Poly (Ethylene Glycol)-Tyramine Hydrogel System in a Rat Model of Cavernous Nerve Injury.

The number of cases of erectile dysfunction (ED) caused after radical prostatectomy (RP) prostate cancer treatment is increasing steadily. Although various studies have been conducted for treatment of post-RP ED, there is still a need for more effective methods. A dual growth factor incorporated heparin-pluronic/gelatin-poly(ethylene glycol)-tyramine (HP/GPT) hydrogel, which consists of a basic fibroblast growth factor (bFGF)-loaded HP hydrogel and nerve growth factor (NGF)-loaded GPT hydrogel, can control dose and rate of growth factor release. In this study, we demonstrated that dual growth factor incorporated HP/GPT hydrogel could further improve erectile function in a rat model of bilateral cavernous nerve injury (BCNI). We showed that erectile function was decreased after BCNI, but it was further improved by treatment with a dual growth factor incorporated HP/GPT hydrogel compared with groups treated with single growth factor in a rat model of cavernous nerve injury. Also, we observed an increase in cyclic guanosine monophosphate (cGMP) levels in the dual growth factor group when compared with the groups treated with single growth factor. This effect was associated with greater upregulation of nitric oxide synthase and endothelial nitric oxide synthase expression in the penile tissue of the group treated with dual growth factor incorporated HP/GPT than in the other experimental groups. Apoptosis in the penile tissue treated with the dual growth factor incorporated HP/GPT hydrogel was lower than those treated singly with either bFGF or NGF incorporated GPT hydrogel. Both α-smooth muscle actin and CD31 expression increased in the group treated with dual growth factor incorporated HP/GPT hydrogel when compared to in the other experimental groups. Altogether, our results proved that the sequential and continuous release of growth factors from dual growth factor incorporated HP/GPT hydrogel prevented fibrosis and nerve damage induced by BCNI in the corpus cavernosum, and promoted the recovery of erectile function. Dual growth factor incorporated HP/GPT hydrogel may be a potent clinical application for the treatment of post-RP ED and could potentially be used various biomedical application in tissue regnerative medicine.

GV1001 Induces Apoptosis by Reducing Angiogenesis in Renal Cell Carcinoma Cells Both In Vitro and In Vivo.

OBJECTIVE: To investigate the anticancer effects of GV1001 and its biological mechanism of action in renal cell carcinoma (RCC). METHODS: The effects of GV1001 on cell survival and apoptosis in RCC cells were examined in vitro using cell viability assay, fluorescence-activated cell sorting, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay. To evaluate the effect of GV1001 on migration, invasion, and angiogenesis, we used wound healing, invasion, endothelial cell tube formation assay, and western blot analysis. Furthermore, we used an RCC xenograft model with either phosphate buffered saline or GV1001 to confirm the anticancer effect of GV1001 in vivo. Tumor volume was monitored during treatment, and tumor weight was measured after animals were killed. Apoptosis and angiogenesis of the tumor tissue were assessed using hematoxylin and eosin staining, immunohistochemistry, and western blot analysis. RESULTS: GV1001 reduced cell viability and induced apoptosis in RCC cells in vitro. Furthermore, GV1001 suppressed the migration and invasion of RCC cells through regulation of matrix metalloproteinases and tissue inhibitors of metalloproteinases. In addition, GV1001 reduced angiogenesis via regulation of hypoxia-inducible factor 1α. In xenograft mouse model experiment, GV1001 reduced tumor growth and induced apoptosis. As in the in vitro results, GV1001 significantly reduced angiogenesis through regulation of hypoxia-inducible factor 1α in vivo. CONCLUSION: Our data demonstrated that GV1001 induced apoptosis through suppression of angiogenesis in RCCs both in vitro and in vivo, which suggests that GV1001 may be a potential therapeutic target for RCC.

In vivo targeting of c-Met using a non-standard macrocyclic peptide in gastric carcinoma.

Development of c-Met targeting probes based on specifically designed peptides with high affinity and stability could help enhance diagnostic efficacy and therapeutic effects in c-Met positive cancers. The Random non-standard Peptides Integrated Discovery (RaPID) system for synthesizing natural product-like macrocyclic peptides via in vitro translation-based selection has recently emerged to overcome the shortcomings of traditional peptide synthesis. Here, we developed non-standard macrocyclic peptides specific to c-Met, and examined the cancer-targeting efficiency of fluorescein-labeled (FL) anti-c-Met peptides, referred to as aML5-FL and aMD4-FL, both in vitro and in vivo. The aML5-FL effectively targeted SNU-638 gastric cancer cells with high c-Met expression, compared to the aMD4-FL due to its high affinity. After intravenous administration of aML5-FL in a tumor xenograft mouse model, FL signal intensity in the extracted SNU-638 tumors was higher than that in SNU-216 tumors. This study provides preclinical data for the usefulness of novel non-standard macrocyclic peptides developed by the RaPID system for specific biomarker imaging.

DJ-1 protects against undernutrition-induced atrophy through inhibition of the MAPK-ubiquitin ligase pathway in myoblasts.

AIMS: The purpose of this study is to explore whether antioxidant DJ-1 protein affects the atrophy of skeletal muscle cell induced by undernutrition. MAIN METHODS: To determine cell atrophic responses, L6 cell line and skeletal primary cells from mouse hind limbs were cultivated under condition of FBS-free and low glucose. Changes of protein expression were analyzed using Western blot. Overexpression and knockdown of DJ-1 was performed in cells to assess its influence on cell atrophic responses. KEY FINDINGS: Undernutrition decreased cell size and increased the abundance of oxidized form and total form of DJ-1 protein in L6 myoblasts. The undernourished cells revealed an elevation in the expression of muscle-specific RING finger-1 (MuRF-1) and atrogin-1, and in the phosphorylations of p38 mitogen-activated protein kinase (MAPK) and stress-activated protein kinase/c-Jun N-terminal kinase compared with control groups. Moreover, DJ-1-knockout mice showed a decrease in cell size and an enhancement in the expression of MuRF-1 and atrogin-1, as well as in the phosphorylation of MAPKs in gastrocnemius muscles; these changes were also observed in L6 cells transfected with siRNA of DJ-1. On the other hand, L6 cells overexpressing full-length DJ-1 did not exhibit the alterations in cell size and ubiquitin ligases seen after undernourished states of control cells. Myotubes differentiated from L6 cells also showed elevated expression of MuRF-1 and atrogin-1 in response to undernutrition. SIGNIFICANCE: These results suggest that DJ-1 protein may contribute to undernutrition-induced atrophy via MAPKs/ubiquitin ligase pathway in skeletal muscle cells.

Selection and characterization of tenascin C targeting peptide.

Since tenascin C is a factor expressed highly in the tumor-associated matrix, it would be a desirable first step for targeting the tumor-specific microenvironment. In fact, a high level of tenascin C expression has been reported in most solid tumors, including lung cancer, colon cancer and glioblastoma. Therefore, the targeted binding of tenascin C in tumor stroma would inhibit tumor metastasis by modulating cancer cell growth and migration. We isolated a peptide that bound to tenascin C by phage display peptide library selection, and the selected peptide specifically recognized tenascin C protein in xenograft mouse tissue. We also observed exclusive staining of tenascin C by the selected peptide in tumor patient tissues. Moreover, the peptide reduced tenascin C-induced cell rounding and migration. We propose that the tenascin C targeting peptide may be useful as a specific anti-cancer diagnostic and therapeutic tool for most human solid tumors.

In vitro selection of RNA aptamer and specific targeting of ErbB2 in breast cancer cells.

The ErbB family (also referred to as HER/neu or HER) of receptor tyrosine kinases plays major roles in the formation and progression of human tumors. Amplification and/or overexpression of ErbB2 have been reported in numerous cancers, including breast, ovarian, stomach, bladder, salivary, and lung cancers. As ErbB2 has been used as a target for the treatment of advanced cancer, RNA aptamers for the extracellular domain of the ErbB2 were selected from a RNA library consisting of 2'-fluorine-modified RNA transcripts. After 15 cycles of selection, high-affinity RNA aptamer was isolated. Binding patterns of the selected RNA aptamer clones were evaluated to choose RNA aptamers that were specific to the extracellular domain of ErbB2 protein. RNA aptamer 15-8 was the best candidate and its minimal version (mini-aptamer) was chemically synthesized. Surface plasmon resonance measurement showed that the mini-aptamer specifically bound to the ErbB2 protein with high affinity and specificity. To evaluate its potential as an ErbB2-targeting molecule in breast cancer cells, specific recognition of the mini-aptamer was confirmed with various breast cancer cell lines. We propose that the selected RNA aptamer is a potential cancer imaging agent by targeting malignant cells overexpressing the ErbB2 receptor.

Modulation of transcription by the peroxisome proliferator-activated receptor delta--binding RNA aptamer in colon cancer cells.

Peroxisome proliferator-activated receptor delta (PPAR-delta), one of three PPAR subtypes, is a lipid-sensing nuclear receptor that has been implicated in multiple processes, including inflammation and cancer. To directly establish the role of PPAR-delta in colon cancer development and progression, we selected high-affinity RNA aptamers and expressed them in several colon cancer cell lines. Nuclear-expressed aptamers efficiently inhibited PPAR-delta-dependent transcription from a synthetic peroxisome proliferator response element-driven luciferase reporter. PPAR-delta-specific aptamers suppressed transcription from natural promoters of vascular endothelial cell growth factor-A and cyclooxygenase-2. Moreover, vascular endothelial cell growth factor-A and cyclooxygenase-2 mRNA levels were significantly reduced by the PPAR-delta-specific aptamers in colon cancer cells. Most significantly, HCT116 colon cancer cells with high-level expression of PPAR-delta-specific aptamers exhibited a striking loss of tumorigenic potential. Further study on these RNA aptamers could provide an opportunity to modulate PPAR-delta-mediated colon cancer development and progression. Taken together, our results establish an important role for PPAR-delta in transcription of tumor-promoting genes, which can be specifically modulated by high-affinity RNA intramers in colon cancer cells. The RNA intramers may be further developed as specific inhibitors for cancer therapeutic strategies.

Use of RNA aptamers for the modulation of cancer cell signaling.

Aptamers are in vitro evolved molecules that bind to target proteins with high affinity and specificity by adapting three-dimensional structures upon binding. Because cancer cells exhibit the activation of signaling pathways that are not usually activated in normal cells, RNA aptamers against such a cancer cell-specific signal can be useful lead molecules for cancer gene therapy. The Wnt/beta-catenin signaling pathway plays important roles in a critical initiating event in the formation of various human cancers. Because mutations in beta-catenin have been found to be responsible for human tumorigenesis, beta-catenin is the molecular target for effective anticancer therapies. Here, we describe the selection of RNA aptamers against beta-catenin/T-Cell Factor (TCF) proteins and their intracellular expression as intramers. The RNA aptamers acted as central inhibitory players for multiple oncogenic functions of beta-catenin in colon cancer cells. These data provide the proof-of-principle for the use of RNA aptamers for an effective anticancer gene therapy.