Chuanliang Xu

Long non-coding RNA metastasis associated in lung adenocarcinoma transcript 1 derived miniRNA as a novel plasma-based biomarker for diagnosing prostate cancer

Examining plasma RNA is an emerging non-invasive diagnosis technique. However, whether tumour-derived long non-coding RNAs (lncRNAs) in plasma can be used as a novel approach to detect human prostate cancer (PCa) has not yet been established. The study was divided into three parts: (1) the characteristics of PCa-related lncRNA fragments were systematically studied in the plasma or serum of 25 patients; (2) the source of the circulating lncRNA fragments was explored in vitro and in vivo; and (3) the diagnostic performance of metastasis associated in lung adenocarcinoma transcript 1 (MALAT-1) derived (MD) miniRNA was validated in an independent cohort of 192 patients. The expression levels of lncRNAs were measured by quantitative real time polymerase chain reaction (qRT-PCR). The MD-miniRNA copies were calculated using a standard curve in an area under the ROC curve (AUC)-receiver operating characteristic (ROC) analysis. Genome-wide profiling revealed that MALAT-1 and prostate cancer gene 3 (PCA3) are overexpressed in PCa tissues. Plasma lncRNAs probably exist in the form of fragments in a stable form. MD-miniRNA enters cell culture medium at measurable levels, and MD-miniRNA derived from human PCa xenografts actually enters the circulation in vivo and can be measured to distinguish xenografted mice from controls. In addition, plasma MD-miniRNA levels are significantly elevated in PCa patients compared to non-PCa patients (p<0.001). At a cut-off of 867.8 MD-miniRNA copies per microlitre of plasma, the sensitivity is 58.6%, 58.6% and 43.5% and the specificity is 84.8%, 84.8% and 81.6% for discriminating PCa from non-PCa, positive biopsy from negative biopsy and positive biopsy from negative biopsy, respectively. We conclude that MD-miniRNA can be used as a novel plasma-based biomarker for PCa detection and can improve diagnostic accuracy by predicting prostate biopsy outcomes. Further large-scale studies are needed to confirm our findings.

Long noncoding RNA MALAT-1 is a new potential therapeutic target for castration resistant prostate cancer.

PURPOSEnTo understand the role of MALAT-1 in prostate cancer we evaluated its expression in prostate cancer tissues and cell lines. We also studied the therapeutic effects of MALAT-1 silencing on castration resistant prostate cancer cells inxa0vitro and inxa0vivo.nnnMATERIALS AND METHODSnQuantitative reverse transcriptase-polymerase chain reaction was used to detect MALAT-1 expression in prostate cancer tissues and cell lines. siRNA against MALAT-1 was designed and the silencing effect was examined by quantitative reverse transcriptase-polymerase chain reaction. The biological effects of MALAT-1 siRNA on cells were investigated by examining cell proliferation using a cell counting kit and cell colony assays as well as cell migration by inxa0vitro scratch assay, cell invasion by Transwell® invasion assay and cell cycle by flow cytometry. We further investigated the effect of therapeutic siRNA targeting MALAT-1 on castration resistant prostate cancer inxa0vivo.nnnRESULTSnMALAT-1 was up-regulated in human prostate cancer tissues and cell lines. Higher MALAT-1 expression correlated with high Gleason score, prostate specific antigen, tumor stage and castration resistant prostate cancer. MALAT-1 down-regulation by siRNA inhibited prostate cancer cell growth, invasion and migration, and induced castration resistant prostate cancer cell cycle arrest in the G0/G1 phases. Importantly, intratumor delivery of therapeutic siRNA targeting MALAT-1 elicited delayed tumor growth and reduced metastasis of prostate cancer xenografts in castrated male nude mice, followed by the concomitant prolongation of survival of tumor bearing mice.nnnCONCLUSIONSnMALAT-1 may be needed to maintain prostate tumorigenicity and it is involved in prostate cancer progression. Thus, MALAT-1 may serve as a potential therapeutic target for castration resistant prostate cancer.

Genome-wide association study in Chinese men identifies two new prostate cancer risk loci at 9q31.2 and 19q13.4

Prostate cancer risk–associated variants have been reported in populations of European descent, African-Americans and Japanese using genome-wide association studies (GWAS). To systematically investigate prostate cancer risk–associated variants in Chinese men, we performed the first GWAS in Han Chinese. In addition to confirming several associations reported in other ancestry groups, this study identified two new risk-associated loci for prostate cancer on chromosomes 9q31.2 (rs817826, P = 5.45 × 10−14) and 19q13.4 (rs103294, P = 5.34 × 10−16) in 4,484 prostate cancer cases and 8,934 controls. The rs103294 marker at 19q13.4 is in strong linkage equilibrium with a 6.7-kb germline deletion that removes the first six of seven exons in LILRA3, a gene regulating inflammatory response, and was significantly associated with the mRNA expression of LILRA3 in T cells (P < 1 × 10−4). These findings may advance the understanding of genetic susceptibility to prostate cancer.

Ursolic acid induces PC-3 cell apoptosis via activation of JNK and inhibition of Akt pathways in vitro

Ursolic acid (UA), a pentacyclic triterpenoid compound, has been demonstrated to have an antiproliferative effect in various tumors. We investigated the cell killing effects of UA in the human hormone refractory prostate cancer cell line, PC‐3 cells. Also, the molecular mechanisms underlying its antigrowth effect were explored. We found that UA treatment in vitro can effectively inhibit PC‐3 cell viability in a dose‐dependent manner by inducing apoptosis, demonstrated by annexin V‐FITC/propidium iodide staining. Both extrinsic and intrinsic apoptotic pathways appear to be triggered by UA treatment, because inhibiting activation of both caspase‐8 and ‐9 could prevent UA‐induced apoptosis in PC‐3 cells. The c‐Jun N‐terminal kinase (JNK) was found to be activated, followed by Bcl‐2 phosphorylation and activation of caspase‐9. On the other hand, UA inhibited the Akt pathway, subsequently upregulating the expression of Fas ligand (FasL), which initiates death receptor‐mediated apoptosis in PC‐3 cells. Importantly, experimentally lowering FasL expression by siRNA significantly inhibited UA‐induced caspase‐8 activation and at least partly attenuated the consequent apoptosis, suggesting an involvement of FasL and its regulating pathway in the cell killing effect of UA. UA also inhibited cell invasion by downregulating matrix metalloproteinase‐9 via inhibition of Akt in PC‐3 cells. Although further evaluation of the UA effects in vivo is needed, the present results suggest the potential utility of UA as a novel therapeutic agent in advanced prostate cancer.

Phosphorylation of Bcl-2 and activation of caspase-3 via the c-Jun N-terminal kinase pathway in ursolic acid-induced DU145 cells apoptosis

There is currently no successful therapy for androgen-independent prostate cancer. Ursolic acid (UA), a pentacyclic triterpenoid compound, has been shown to have an anti-proliferative effect on various tumors. We investigated the effect of UA on cell viability in the human hormone-refractory prostate cancer cell line DU145, as well as the molecular mechanisms underlying its growth inhibiting effect. We demonstrated that UA induces apoptosis and the activation of caspase-3 in DU145 cells. UA also causes the activation of c-Jun N-terminal kinase (JNK), but has no effect on extracellular signal-regulated protein kinases (ERK1/2) and p38 MAP kinases (p38). UA-induced JNK activation could result in Bcl-2 phosphorylation (Ser70) and degradation in DU145 cells, which may be one of the molecular mechanisms by which it induces apoptosis. Although further evaluation, such as in vivo testing, is clearly needed, the present results suggest the potential utility of UA as a novel therapeutic agent in advanced prostate cancer.

A novel Germline mutation in HOXB13 is associated with prostate cancer risk in Chinese men

A rare mutation G84E in HOXB13 was recently identified to be associated with prostate cancer (PCa) in Caucasians. The goal of this study is to test association between HOXB13 genetic variants and PCa risk in Chinese men.

Ursolic acid overcomes Bcl‐2‐mediated resistance to apoptosis in prostate cancer cells involving activation of JNK‐induced Bcl‐2 phosphorylation and degradation

Androgen‐independent prostate cancers express high levels of Bcl‐2, and this over‐expression of Bcl‐2 protects prostate cancer cells from undergoing apoptosis. Ursolic acid (UA) has demonstrated an anti‐proliferative effect in various tumor types. The aim of this study is to evaluate the difference between UA‐induced apoptosis in androgen‐dependent prostate cancer cell line LNCaP cells and androgen‐independent prostate cancer cell line LNCaP‐AI cells and to reveal the molecular mechanisms underlying the apoptosis. We found that UA treatment in vitro can effectively induce apoptosis in LNCaP and LNCaP‐AI cells. UA can overcome Bcl‐2‐mediated resistance to apoptosis in LNCaP‐AI cells. Intrinsic apoptotic pathways can be triggered by UA treatment because c‐Jun N‐terminal kinase (JNK) is activated and subsequently provokes Bcl‐2 phosphorylation and degradation, inducing activation of caspase‐9. Although further evaluation is clearly needed, the present results suggest the potential utility of UA as a novel therapeutic agent in advanced prostate cancer. J. Cell. Biochem. 109: 764–773, 2010.

Oncogenic CUL4A determines the response to thalidomide treatment in prostate cancer

Thalidomide is experimentally used to treat various human cancers; however, clinical responses to thalidomide are sporadic. Here we demonstrate that CUL4A plays an oncogenic role in prostate cancer development and prostate cancer cells with higher level of CUL4A are particularly sensitive to thalidomide treatment. We show that CUL4A is frequently overexpressed in human primary prostate cancer and cell lines. Notably, subjects with tumors that highly expressed CUL4A had poor overall survival. CUL4A downregulation inhibited cell proliferation and induced apoptosis in vitro and in vivo, whereas CUL4A overexpression transformed human normal prostate epithelial cells and promoted invasion, which was attenuated by the extracellular signal-regulated kinase (ERK) inhibitor. We further show that the sensitivity to thalidomide is positively correlated with CUL4A expression in a panel of prostate cell lines. Ectopic CUL4A expression greatly enhanced sensitivity to thalidomide, while its downregulation conferred resistance to this drug. Mechanistically, thalidomide decreased CUL4A in a time- and dose-dependent manner, consequently leading to inaction of ERK pathway. Finally, we show that cereblon level is correlated with CUL4A expression and downregulated in thalidomide-resistant prostate cancer cell. Our results offer the first evidence that CUL4A is a potential therapeutic target for prostate cancer and may serve as a biomarker for assessing prognosis of human prostate cancer and response to thalidomide treatment.

Human Bone Marrow-Derived Mesenchymal Stem Cells produced TGFbeta Contributes to Progression and Metastasis of Prostate Cancer

Human mesenchymal stem cells (hMSCs) play an important role in the development of human cancers. In the present study, we observed that hMSCs promoted human prostate cancer (PCa) cell PC-3 growth in vivo and in vitro. The conditional medium of hMSCs promoted the proliferation, migration, and invasion of PC-3 cells. The expression of MMP-2 and MMP-9 in PC-3 was upregulated by conditional medium of hMSCs. In addition, blocking tumor transformation factor beta (TGFβ) blunted the pro-oncogenic function of hMSCs. These results suggest that hMSCs may play a pro-oncogenic role in the growth of human prostate caner by producing TGFβ.

Hypoxia-Induced Apoptosis in the Bilateral Testes of Rats With Left-Sided Varicocele: A New Way to Think About the Varicocele

Although the varicocele has been studied for many years, its pathophysiology remains unclear. In this study, we investigated the expression of the alpha subunit of hypoxia-inducible factor 1 (HIF-1 alpha) and determined the apoptosis index (AI) in the testes of rats with varicoceles to study the mechanism by which varicoceles induce infertility. A total of 45 Wistar rats were divided into 3 groups: control group, sham surgery group, and experimental group. Forty-nine days after the initial partial ligation of the left renal vein, all of the rats underwent orchiectomy. HIF-1 alpha expression in each testis was analyzed using immunohistochemical methods and enzyme-linked immunosorbent assay. The degree of apoptosis within each testicle was determined using terminal deoxynucleotidyl transferase dUTP nick end labeling. HIF-1 alpha immunoreactivity in the testes of the experimental group was significantly higher than that in those of the control group (P < .05) or the sham group (P < .05). The AI of the germ cells of rats in the experimental group was significantly higher than that in germ cells of rats in the sham group (P < .001) or the control group (P < .001). Additionally, there was a significant positive correlation observed between the AI of germ cells and relative intensity of HIF-1 alpha in the left testis (r = .631; P = .028) and right testis (r = .707; P = .01) of rats in the experimental group. The results of this study showed that a left-sided varicocele could cause bilateral testicular hypoxia and increased germ cell apoptosis, both of which play an important role in testicular dysfunction. Furthermore, HIF-1 alpha is a useful factor that can be used to predict the degree of germ cell apoptosis in rat testes.