Accelerating Cellular Uptake with Unnatural Amino Acid for Inhibiting Immunosuppressive Cancer Cells.

Targeting immunosuppressive metastatic cancer cells is a key challenge in therapy. We recently have shown that a rigid-rod aromatic, pBP-NBD, that responds to enzymes and kill immunosuppressive metastatic osteosarcoma (mOS) and castration resistant prostate cancer (CRPC) cells in mimetic bone microenvironment. However, pBP-NBD demonstrated moderate efficacy against CRPC cells. To enhance activity, we incorporated the unnatural amino acid L- or D-4,4'-biphenylalanine (L- or D-BiP) into pBP-NBD, drastically increasing cellular uptake and CRPC inhibition. Specifically, we inserted BiP into pBP-NBD to target mOS (Saos2 and SJSA1) and CRPC (VCaP and PC3) cells with overexpressed phosphatases. Our results show that the D-peptide backbone with an aspartate methyl diester at the C-terminal offers the highest activity against these immunosuppressive mOS and CRPC cells. Importantly, imaging shows that the peptide assemblies almost instantly enter the cells and accumulate primarily within the endoplasmic reticulum of Saos2, SJSA1, and PC3 cells and at the lysosomes of VCaP cells. By using BiP to boost cellular uptake and self-assembly within cancer cells, this work illustrates an unnatural hydrophobic amino acid as a versatile and effective residue to boost endocytosis of synthetic peptides for intracellular self-assembly.

Enzyme Responsive Rigid-Rod Aromatics Target "Undruggable" Phosphatases to Kill Cancer Cells in a Mimetic Bone Microenvironment.

Bone metastasis remains a challenge in cancer treatment. Here we show enzymatic responsive rigid-rod aromatics acting as the substrates of "undruggable" phosphatases to kill cancer cells in a mimetic bone microenvironment. By phosphorylation and conjugating nitrobenzoxadiazole (NBD) to hydroxybiphenylcarboxylate (BP), we obtained pBP-NBD (1P) as a substrate of both acid and alkaline phosphatases. 1P effectively kills both metastatic castration-resistant prostate cancer cells (mCRPCs) and osteoblast mimic cells in their coculture. 1P enters Saos2 almost instantly to target the endoplasmic reticulum (ER) of the cells. Co-culturing with Saos2 cells boosts the cellular uptake of 1P by mCRPCs. Cryo-EM reveals the nanotube structures of both 1P (2.4 Å resolution, pH 5.6) and 1 (2.2 Å resolution, pH 7.4). The helical packing of both nanotubes is identical, held together by strong pi-stacking interactions. Besides reporting the atomistic structure of nanotubes formed by the assembly of rigid-rod aromatics, this work expands the pool of molecules for designing EISA substrates that selectively target TME.

Antrodia salmonea extract inhibits cell proliferation through regulating cell cycle arrest and apoptosis in prostate cancer cell lines.

Antrodia salmonea (AS) is a fungus, which belongs to a fungal family of Taiwanofungus salmoneus with the features of anti-oxidant, anti-inflammatory, and anticancer. Recent studies have shown that AS has anti-cancer functions in ovarian and breast cancer. However, the effects of AS on prostate cancer (PCa) proliferation remain unknown. Therefore, we investigated the role of AS in PCa proliferation through apoptosis, and cell cycle regulation in PCa cell lines. Our results showed that Antrodia salmonea extract (ASE) inhibited PCa cells growth with a dose-dependent manner. In addition, ASE decreased the anchorage-independent growth formation ability in PC3 cells. Moreover, ASE-induced cell growth inhibition in PCa cells (DU145, PC3) was correlated to decreased cell cycle-related proteins such as cyclin A/B and cyclin-dependent kinase CDK1/2/4, and increased cell cycle inhibitor proteins p21. Besides, ASE decreased the total protein level of epidermal growth factor receptor and its downstream signaling pathways Akt and Erk in both PCa cells. We found that apoptotic markers such as cleaved-PARP protein levels increased significantly in DU145 cells indicating ASE might induce apoptosis. In conclusion, our results suggest that ASE may have the ability to induce PCa cell death through regulating cell cycle arrest and apoptosis pathways.

SPARC is a key mediator of TGF-ß-induced renal cancer metastasis.

Aberrant expression of transforming growth factor-ß1 (TGF-ß1) is associated with renal cell carcinoma (RCC) progression by inducing cancer metastasis. However, the downstream effector(s) in TGF-ß signaling pathway is not fully characterized. In the present study, the elevation of secreted protein acidic and rich in cysteine (SPARC) as a TGF-ß regulated gene in RCC was identified by applying differentially expressed gene analysis and microarray analysis, we further confirmed this result in several RCC cell lines. Clinically, the expression of these two genes is positively correlated in RCC patient specimens. Furthermore, elevated SPARC expression is found in all the subtypes of RCC and positively correlated with the RCC stage and grade. In contrast, SPARC expression is inversely correlated with overall and disease-free survival of patients with RCC, suggesting SPARC as a potent prognostic marker of RCC patient survival. Knocking down SPARC significantly inhibits RCC cell invasion and metastasis both in vitro and in vivo. Similarly, in vitro cell invasion can be diminished by using a specific monoclonal antibody. Mechanistically, SPARC activates protein kinase B (AKT) pathway leading to elevated expression of matrix metalloproteinase-2 that can facilitate RCC invasion. Altogether, our data support that SPARC is a critical role of TGF-ß signaling network underlying RCC progression and a potential therapeutic target as well as a prognostic marker.

Interethnic differences in the impact of body mass index on upper tract urothelial carcinoma following radical nephroureterectomy.

PURPOSE: Inconsistent prognostic implications of body mass index (BMI) in upper tract urothelial carcinoma (UTUC) have been reported across different ethnicities. In this study, we aimed to analyze the oncologic role of BMI in Asian and Caucasian patients with UTUC. METHODS: We retrospectively collected data from 648 Asian Taiwanese and 213 Caucasian American patients who underwent radical nephroureterectomy for UTUC. We compared clinicopathologic features among groups categorized by different BMI. Kaplan-Meier method and Cox regression model were used to examine the impact of BMI on recurrence and survival by ethnicity. RESULTS: According to ethnicity-specific criteria, overweight and obesity were found in 151 (23.2%) and 215 (33.2%) Asians, and 79 (37.1%) and 78 (36.6%) Caucasians, respectively. No significant association between BMI and disease characteristics was detected in both ethnicities. On multivariate analysis, overweight and obese Asians had significantly lower recurrence than those with normal weight (HR 0.631, 95% CI 0.413-0.966; HR 0.695, 95% CI 0.493-0.981, respectively), and obesity was an independent prognostic factor for favorable cancer-specific and overall survival (HR 0.521, 95% CI 0.342-0.794; HR 0.545, 95% CI 0.386-0.769, respectively). There was no significant difference in outcomes among normal, overweight and obese Caucasians, but obese patients had a relatively poorer 5-year RFS, CSS, and OS rates of 52.8%, 60.5%, and 47.2%, compared to 54.9%, 69.1%, and 54.9% for normal weight patients. CONCLUSION: Higher BMI was associated with improved outcomes in Asian patients with UTUC. Interethnic differences could influence preoperative counseling or prediction modeling in patients with UTUC.

Histone lysine demethylase KDM4B regulates the alternative splicing of the androgen receptor in response to androgen deprivation.

Alternative splicing is emerging as an oncogenic mechanism. In prostate cancer, generation of constitutively active forms of androgen receptor (AR) variants including AR-V7 plays an important role in progression of castration-resistant prostate cancer (CRPC). AR-V7 is generated by alternative splicing that results in inclusion of cryptic exon CE3 and translation of truncated AR protein that lacks the ligand binding domain. Whether AR-V7 can be a driver for CRPC remains controversial as the oncogenic mechanism of AR-V7 activation remains elusive. Here, we found that KDM4B promotes AR-V7 and identified a novel regulatory mechanism. KDM4B is phosphorylated by protein kinase A under conditions that promote castration-resistance, eliciting its binding to the splicing factor SF3B3. KDM4B binds RNA specifically near the 5'-CE3, upregulates the chromatin accessibility, and couples the spliceosome to the chromatin. Our data suggest that KDM4B can function as a signal responsive trans-acting splicing factor and scaffold that recruits and stabilizes the spliceosome near the alternative exon, thus promoting its inclusion. Genome-wide profiling of KDM4B-regulated genes also identified additional alternative splicing events implicated in tumorigenesis. Our study defines KDM4B-regulated alternative splicing as a pivotal mechanism for generating AR-V7 and a contributing factor for CRPC, providing insight for mechanistic targeting of CRPC.

Validation of SV2A-Targeted PET Imaging for Noninvasive Assessment of Neuroendocrine Differentiation in Prostate Cancer.

Neuroendocrine prostate cancer (NEPC) is an aggressive and lethal variant of prostate cancer (PCa), and it remains a diagnostic challenge. Herein we report our findings of using synaptic vesicle glycoprotein 2 isoform A (SV2A) as a promising marker for positron emission tomography (PET) imaging of neuroendocrine differentiation (NED). The bioinformatic analyses revealed an amplified SV2A gene expression in clinical samples of NEPC versus castration-resistant PCa with adenocarcinoma characteristics (CRPC-Adeno). Importantly, significantly upregulated SV2A protein levels were found in both NEPC cell lines and tumor tissues. PET imaging studies were carried out in NEPC xenograft models with 18F-SynVesT-1. Although 18F-SynVesT-1 is not a cancer imaging agent, it showed a significant uptake level in the SV2A+ tumor (NCI-H660: 0.70 ± 0.14 %ID/g at 50-60 min p.i.). The SV2A blockade resulted in a significant reduction of tumor uptake (0.25 ± 0.03 %ID/g, p = 0.025), indicating the desired SV2A imaging specificity. Moreover, the comparative PET imaging study showed that the DU145 tumors could be clearly visualized by 18F-SynVesT-1 but not 68Ga-PSMA-11 nor 68Ga-DOTATATE, further validating the role of SV2A-targeted imaging for noninvasive assessment of NED in PCa. In conclusion, we demonstrated that SV2A, highly expressed in NEPC, can serve as a promising target for noninvasive imaging evaluation of NED.

Hyperfluorescence Imaging of Kidney Cancer Enabled by Renal Secretion Pathway Dependent Efflux Transport.

Renal tubular secretion is an active efflux pathway for the kidneys to remove molecules but has yet to be used to enhance kidney cancer targeting. We report indocyanine green (ICG) conjugated with a 2100 Da PEG molecule (ICG-PEG45) as a renal-tubule-secreted near-infrared-emitting fluorophore for hyperfluorescence imaging of kidney cancers, which cannot be achieved with hepatobiliary- and glomerular-clearable ICG. This pathway-dependent targeting of kidney cancer arises from the fact that the secretion pathway enables ICG-PEG45 to be effectively effluxed out of normal proximal tubules through P-glycoprotein transporter while being retained in cancerous kidney tissues with low P-glycoprotein expression. Tuning elimination pathways and utilizing different efflux kinetics of medical agents in normal and diseased tissues could be a new strategy for tackling challenges in disease diagnosis and treatments that cannot be addressed with passive and ligand-receptor-mediated active targeting.

The AKR1C3/AR-V7 complex maintains CRPC tumour growth by repressing B4GALT1 expression.

Multiple mechanisms contribute to the survival and growth of metastatic castration-resistant prostate cancer (mCRPC) cells without androgen, including androgen receptor splice variants (AR-V) and de novo intratumoral androgen synthesis. AKR1C3 is a critical androgenic enzyme that plays different roles in mCRPC, such as an EMT driver or AR coactivator. However, the relationship and regulatory mechanisms between AKR1C3 and AR-V remain largely unknown. In this study, we observed a positive correlation between AKR1C3 and AR-V7 staining in tissues from prostate rebiopsy at mCRPC. Mechanistically, AKR1C3 interacts with AR-V7 protein in CRPC cells, which can reciprocally inhibit AR-V7 and AKR1C3 protein degradation. Biologically, this complex is essential for in vitro and in vivo tumour growth of CRPC cells after androgen deprivation as it represses B4GALT1, a unique tumour suppressor gene in PCa. Together, this study reveals AKR1C3/AR-V7 complex as a potential therapeutic target in mCRPC.

Future Aspects of CDK5 in Prostate Cancer: From Pathogenesis to Therapeutic Implications.

Cyclin-dependent kinase 5 (CDK5) is a unique member of the cyclin-dependent kinase family. CDK5 is activated by binding with its regulatory proteins, mainly p35, and its activation is essential in the development of the central nervous system (CNS) and neurodegeneration. Recently, it has been reported that CDK5 plays important roles in regulating various biological and pathological processes, including cancer progression. Concerning prostate cancer, the androgen receptor (AR) is majorly involved in tumorigenesis, while CDK5 can phosphorylate AR and promotes the proliferation of prostate cancer cells. Clinical evidence has also shown that the level of CDK5 is associated with the progression of prostate cancer. Interestingly, inhibition of CDK5 prevents prostate cancer cell growth, while drug-triggered CDK5 hyperactivation leads to apoptosis. The blocking of CDK5 activity by its small interfering RNAs (siRNA) or Roscovitine, a pan-CDK inhibitor, reduces the cellular AR protein level and triggers the death of prostate cancer cells. Thus, CDK5 plays a crucial role in the growth of prostate cancer cells, and AR regulation is one of the important pathways. In this review paper, we summarize the significant studies on CDK5-mediated regulation of prostate cancer cells. We propose that the CDK5-p35 complex might be an outstanding candidate as a diagnostic marker and potential target for prostate cancer treatment in the near future.

Correlating Anticancer Drug Delivery Efficiency with Vascular Permeability of Renal Clearable Versus Non-renal Clearable Nanocarriers.

Enhancing tumor targeting of nanocarriers has been a major strategy for advancing clinical translation of cancer nanomedicines. Herein, we report a head-to-head comparison between 5 nm renal clearable and 30 nm non-renal clearable gold nanoparticle (AuNP)-based drug delivery systems (DDSs) in the delivery of doxorubicin (DOX). While the two DDSs themselves had comparable tumor targeting, we found their different vascular permeability played an even more important role than blood retention in the delivery and intratumoral transport of DOX, of which tumor accumulation, efficacy, and therapeutic index were enhanced 2, 7, and 10-fold, respectively, for the 5 nm DDS over 30 nm one. These findings indicate that ultrahigh vascular permeability of renal clearable nanocarriers can be utilized to further improve anticancer drug delivery without the need for prolonged blood retention.

Photoacoustic Imaging of Nanoparticle Transport in the Kidneys at High Temporal Resolution.

Noninvasive monitoring of kidney elimination of engineered nanoparticles at high temporal and spatial resolution will not only significantly advance our fundamental understandings of nephrology on the nanoscale, but also aid in the early detection of kidney disease, which affects more than 10 % of the worldwide population. Taking advantage of strong NIR absorption of the well-defined Au25 (SG)18 nanocluster, photoacoustic (PA) imaging was used to visualize its transport in situ through the aorta to the renal parenchyma and its subsequent filtration into the renal pelvis at a temporal resolution down to 1 s. High temporal and spatial resolution imaging of Au25 (SG)18 kidney elimination allowed the accurate quantification of the glomerular filtration rate (GFR) of individual kidneys in normal and pathological conditions, broadening the biomedical applications of engineered nanoparticles in preclinical kidney research.

Tuning the In†Vivo Transport of Anticancer Drugs Using Renal-Clearable Gold Nanoparticles.

Precise control of in vivo transport of anticancer drugs in normal and cancerous tissues with engineered nanoparticles is key to the future success of cancer nanomedicines in clinics. This requires a fundamental understanding of how engineered nanoparticles impact the targeting-clearance and permeation-retention paradoxes in the anticancer-drug delivery. Herein, we systematically investigated how renal-clearable gold nanoparticles (AuNPs) affect the permeation, distribution, and retention of the anticancer drug doxorubicin in both cancerous and normal tissues. Renal-clearable AuNPs retain the advantages of the free drug, including rapid tumor targeting and high tumor vascular permeability. The renal-clearable AuNPs also accelerated body clearance of off-target drug via renal elimination. These results clearly indicate that diverse in vivo transport behaviors of engineered nanoparticles can be used to reconcile long-standing paradoxes in the anticancer drug delivery.

Exosomes in cancer development and clinical applications.

Exosomes participate in cancer progression and metastasis by transferring bioactive molecules between cancer and various cells in the local and distant microenvironments. Such intercellular cross-talk results in changes in multiple cellular and biological functions in recipient cells. Several hallmarks of cancer have reportedly been impacted by this exosome-mediated cell-to-cell communication, including modulating immune responses, reprogramming stromal cells, remodeling the architecture of the extracellular matrix, or even endowing cancer cells with characteristics of drug resistance. Selectively, loading specific oncogenic molecules into exosomes highlights exosomes as potential diagnostic biomarkers as well as therapeutic targets. In addition, exosome-based drug delivery strategies in preclinical and clinical trials have been shown to dramatically decrease cancer development. In the present review, we summarize the significant aspects of exosomes in cancer development that can provide novel strategies for potential clinical applications.

Tumor suppressor protein DAB2IP participates in chromosomal stability maintenance through activating spindle assembly checkpoint and stabilizing kinetochore-microtubule attachments.

Defects in kinetochore-microtubule (KT-MT) attachment and the spindle assembly checkpoint (SAC) during cell division are strongly associated with chromosomal instability (CIN). CIN has been linked to carcinogenesis, metastasis, poor prognosis and resistance to cancer therapy. We previously reported that the DAB2IP is a tumor suppressor, and that loss of DAB2IP is often detected in advanced prostate cancer (PCa) and is indicative of poor prognosis. Here, we report that the loss of DAB2IP results in impaired KT-MT attachment, compromised SAC and aberrant chromosomal segregation. We discovered that DAB2IP directly interacts with Plk1 and its loss inhibits Plk1 kinase activity, thereby impairing Plk1-mediated BubR1 phosphorylation. Loss of DAB2IP decreases the localization of BubR1 at the kinetochore during mitosis progression. In addition, the reconstitution of DAB2IP enhances the sensitivity of PCa cells to microtubule stabilizing drugs (paclitaxel, docetaxel) and Plk1 inhibitor (BI2536). Our findings demonstrate a novel function of DAB2IP in the maintenance of KT-MT structure and SAC regulation during mitosis which is essential for chromosomal stability.

Dose Dependencies and Biocompatibility of Renal Clearable Gold Nanoparticles: From Mice to Non-human Primates.

While dose dependencies in pharmacokinetics and clearance are often observed in clinically used small molecules, very few studies have been dedicated to the understandings of potential dose-dependent in vivo transport of nanomedicines. Here we report that the pharmacokinetics and clearance of renal clearable gold nanoparticles (GS-AuNPs) are strongly dose-dependent once injection doses are above 15 mg kg-1 : high dose expedited the renal excretion and shortened the blood retention. As a result, the no-observed-adverse-effect-level (NOAEL) of GS-AuNPs was >1000 mg kg-1 in CD-1 mice. The efficient renal clearance and high compatibility can be translated to the non-human primates: no adverse effects were observed within 90 days after intravenous injection of 250 mg kg-1 GS-AuNPs. These fundamental understandings of dose effect on the in vivo transport of ultrasmall AuNPs open up a pathway to maximize their biomedical potentials and minimize their toxicity in the future clinical translation.

Developing new targeting strategy for androgen receptor variants in castration resistant prostate cancer.

The presence of androgen receptor variant 7 (AR-V7) variants becomes a significant hallmark of castration-resistant prostate cancer (CRPC) relapsed from hormonal therapy and is associated with poor survival of CRPC patients because of lacking a ligand-binding domain. Currently, it still lacks an effective agent to target AR-V7 or AR-Vs in general. Here, we showed that a novel class of agents (thailanstatins, TSTs and spliceostatin A analogs) can significantly suppress the expression of AR-V7 mRNA and protein but in a less extent on the full-length AR expression. Mechanistically, TST-D is able to inhibit AR-V7 gene splicing by interfering the interaction between U2AF65 and SAP155 and preventing them from binding to polypyrimidine tract located between the branch point and the 3' splice site. In vivo, TST-D exhibits a potent tumor inhibitory effect on human CRPC xenografts leading to cell apoptosis. The machinery associated with AR gene splicing in CRPC is a potential target for drugs. Based on their potency in the suppression of AR-V7 responsible for the growth/survival of CRPC, TSTs representing a new class of anti-AR-V agents warrant further development into clinical application.

Immune Cell-Mediated Biodegradable Theranostic Nanoparticles for Melanoma Targeting and Drug Delivery.

Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell-mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer-specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP-PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti-BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP-PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP-PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell-cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The "self-powered" immune cell-mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.

Ablation of the oncogenic transcription factor ERG by deubiquitinase inhibition in prostate cancer.

The transcription factor E-twenty-six related gene (ERG), which is overexpressed through gene fusion with the androgen-responsive gene transmembrane protease, serine 2 (TMPRSS2) in ∼40% of prostate tumors, is a key driver of prostate carcinogenesis. Ablation of ERG would disrupt a key oncogenic transcriptional circuit and could be a promising therapeutic strategy for prostate cancer treatment. Here, we show that ubiquitin-specific peptidase 9, X-linked (USP9X), a deubiquitinase enzyme, binds ERG in VCaP prostate cancer cells expressing TMPRSS2-ERG and deubiquitinates ERG in vitro. USP9X knockdown resulted in increased levels of ubiquitinated ERG and was coupled with depletion of ERG. Treatment with the USP9X inhibitor WP1130 resulted in ERG degradation both in vivo and in vitro, impaired the expression of genes enriched in ERG and prostate cancer relevant gene signatures in microarray analyses, and inhibited growth of ERG-positive tumors in three mouse xenograft models. Thus, we identified USP9X as a potential therapeutic target in prostate cancer cells and established WP1130 as a lead compound for the development of ERG-depleting drugs.

The Role and Mechanism of Epithelial-to-Mesenchymal Transition in Prostate Cancer Progression.

In prostate cancer (PCa), similar to many other cancers, distant organ metastasis symbolizes the beginning of the end disease, which eventually leads to cancer death. Many mechanisms have been identified in this process that can be rationalized into targeted therapy. Among them, epithelial-to-mesenchymal transition (EMT) is originally characterized as a critical step for cell trans-differentiation during embryo development and now recognized in promoting cancer cells invasiveness because of high mobility and migratory abilities of mesenchymal cells once converted from carcinoma cells. Nevertheless, the underlying pathways leading to EMT appear to be very diverse in different cancer types, which certainly represent a challenge for developing effective intervention. In this article, we have carefully reviewed the key factors involved in EMT of PCa with clinical correlation in hope to facilitate the development of new therapeutic strategy that is expected to reduce the disease mortality.