Inhibition of prostate cancer cell colony formation by the flavonoid quercetin correlates with modulation of specific regulatory genes

The natural product quercetin is a flavonoid found in many fruits and vegetables. Previous research has shown that quercetin has antitumor, anti-inflammatory, antiallergic, and antiviral activities. In the present investigation we studied the effect of quercetin on the ability of prostate cancer cell lines with various degrees of aggressive potential to form colonies in vitro. Specifically, we examined the molecular mechanisms underlying this effect, including the expression of cell cycle and tumor suppressor genes as well as oncogenes. We observed that quercetin at concentrations of 25 and 50 micro M significantly inhibited the growth of the highly aggressive PC-3 prostate cancer cell line and the moderately aggressive DU-145 prostate cancer cell line, whereas it did not affect colony formation by the poorly aggressive LNCaP prostate cancer cell line or the normal fibroblast cell line BG-9. Using the gene array methodology, we found that quercetin significantly inhibited the expression of specific oncogenes and genes controlling G(1), S, G(2), and M phases of the cell cycle. Moreover, quercetin reciprocally up-regulated the expression of several tumor suppressor genes. In conclusion, our results demonstrate that the antitumor effects of quercetin directly correlate with the aggressive potential of prostate cancer cells and that the mechanism(s) of quercetin-mediated antitumor effects may involve up-regulation of tumor suppressor genes and reciprocal down-regulation of oncogenes and cell cycle genes. The results of these studies provide a scientific basis for the potential use of flavonoids as nutraceuticals in the chemoprevention of cancer.     

A novel role of myosin VI in human prostate cancer

Myosin VI is an actin motor that moves to the minus end of the polarized actin filament, a direction opposite to all other characterized myosins. Using expression microarrays, we identified myosin VI as one of the top genes that demonstrated cancer-specific overexpression in clinical prostate specimens. Protein expression of myosin VI was subsequently analyzed in arrayed prostate tissues from 240 patients. Notably, medium-grade prostate cancers demonstrated the most consistent cancer-specific myosin VI protein overexpression, whereas prostate cancers associated with more aggressive histological features continued to overexpress myosin VI but to a lesser extent. Myosin VI protein expression in cell lines positively correlated with the presence of androgen receptor. Small interference RNA-mediated myosin VI knockdown in the LNCaP human prostate cancer cell line resulted in impaired in vitro migration and soft-agar colony formation. Depletion of myosin VI expression was also accompanied by global gene expression changes reflective of attenuated tumorigenic potential, as marked by a nearly 10-fold induction of TXNIP (VDUP1), a tumor suppressor with decreased expression in prostate cancer specimens. These results support that myosin VI is critical in maintaining the malignant properties of the majority of human prostate cancers diagnosed today.     

miR-143 down-regulates TLR2 expression in hepatoma cells and inhibits hepatoma cell proliferation and invasion

Hepatoma is a tumor with high degree of malignancy. A number of oncogenes and tumor suppressor genes play certain roles in tumorigenesis and progression. Among which, miRNA, as an important class of gene regulators, play important roles in regulating tumorigenesis and development of hepatoma. So know well the unique molecular pathway is very important. Here, we showed that there is a different miR-143 expression patterns in different hepatoma tissues, and that miR-143 expressions contribute disease progress. By contrast, we down-regulated the expression of miR-143 with miR-143 mimics in HepG2 cells resulting in decreased proliferation. And the decreased proliferations of HepG2 cells were due to a G₀/G₁ arrest of cell cycle. During this progress, the increased apoptosis may be another major cause for decreased proliferation of HepG2 cells. And then, we found miR-143 down-regulation induced decreased mRNA and protein expressions of TLR2 and NF-κB. These results show that HepG2 cells depend to a greater extent on miR-143 for proliferation, and miR-143 down-regulation may induce a cell cycle arrest though TLR and NF-κB pathway. miR-143 blockade may be beneficial in therapy of Hepatoma.     

Inhibitory effect of miR-184 on the potential of proliferation and invasion in human glioma and breast cancer cells in vitro

MiR-184 was an important suppressor to tumor cells proliferation and invasion and some studies show that it was down-regulated in aggressive human tumor cells and a potential tumor therapy target through expression of miR-184 results in reduced tumor cell aggressiveness. In this study, miR-184 showed an inhibitive activity of glioma U87MG cell line and breast cancer MCF-7 cell line in proliferation and invasion by MTS and transwell assay. We found that the miR-184 also could arrest cell cycle and adhesion by up-regulating the expression of p53 and p21 and activity of caspase-3/8, suppressing the expression of SND1, MMP-2/9, CD44 and activity of AKT/NF-κB pathway. The results showed that miR-184 could be a potential target for glioma and breast cancer treatment.     

Oncogenes and tumor suppressor genes as a tool for clinical diagnosis of solid tumors

Over the past few years, numerous clinical studies have examined genetic technology to detect physical alterations of genes, such as mutations, translocations and amplification of oncogenes, deletion of tumor suppressor genes, the presence of oncogenic viruses, and the expression of genes specific to cancer tissues. The ability to identify individuals at high risk for cancer holds the promise of improved prevention and early diagnosis of cancers. The goal of genetic diagnosis in cancer is to provide information on abnormal oncogenes and tumor suppressor genes using recent molecular biology techniques. We introduced a highly sensitive method of detecting micrometastasis using PCR in prostate cancer, and strategies for guidelines in clinical diagnosis.     

The reciprocal interactions between astrocytes and prostate cancer cells represent an early event associated with brain metastasis

Tumor establishment, growth, and survival are supported by interactions with microenvironment components. Here, we investigated whether the interactions between prostate cancer cells and cortical astrocytes are associated to a potential role for astrocytes in tumor establishment. We demonstrate that astrocytes interact in vitro with prostatic cancers cells derived from different metastatic sites. Astrocytes and their secreted extracellular matrix, stimulate DU145 cell (a brain-derived prostate tumor cell line) proliferation while inhibiting cell death and modulating the expression of several genes related to prostate cancer progression, suggesting the activation of EMT process in these cells. In contrast, DU145 cells and their conditioned medium inhibited cell proliferation and induced cell death of astrocytes. On the other hand, the astrocytes were unable to significantly induce an increment of LNCaP cell (a lymph node-derived prostate tumor cell line) proliferative activity. In addition, LNCaP cells were also unable to induce cell death of astrocytes. Thus, we believe that DU145 cells, but not LNCaP cells, present an even more aggressive behavior when interacting with astrocytes. These results provide an important contribution to the elucidation of the cellular mechanisms involved in the brain microenvironment colonization.     

SOX1 inhibits breast cancer cell growth and invasion through suppressing the Wnt/β‐catenin signaling pathway

Abnormal activation of the Wnt/β‐catenin signaling pathway is common in human cancers. Several studies have demonstrated that SRY (sex‐determining region Y)‐box (SOX) family genes serve as either tumor suppressor genes or oncogenes by regulating the Wnt signaling pathway in different cancers. However, the role of SOX1 in breast cancer and the underlying mechanism is still unclear. The aim of this study was to explore the effect and mechanism of SOX1 on the breasted cancer cell growth and invasion. In this study, we established overexpressed SOX1 and investigated its function by in vitro experiments. SOX1 was down‐regulated in breast cancer tissues and cell lines. Overexpression of SOX1 inhibited cell proliferation and invasion in vitro, and it promoted cell apoptosis. Furthermore, SOX1 inhibited the expression of β‐catenin, cyclin D1, and c‐Myc in breast cancer cells. Taken together, these data suggest that SOX1 can function as a tumor suppressor partly by interfering with Wnt/β‐catenin signaling in breast cancer.     

Analysis of laser-microdissected prostate cancer tissues reveals potential tumor markers

Prostate cancer (PCA) is a clinically heterogeneous and often multifocal disease with a clinical outcome difficult to predict. A deeper knowledge of the molecular basis of the disease may lead to a better prediction of prognosis. Therefore, in this study we investigated the molecular basis of PCA by identifying potential tumor markers in laser-microdisected PCA tissues. Among a group of PCA patients, quantitative RT-PCR analysis was performed to compare the expression of 70 genes. These genes were selected from the results of two microarrays which investigated the gene expression profile differences between moderately or poorly differentiated prostate carcinoma glands and the corresponding normal glands. Among the genes examined, CDKN2A, GATA3, CREBBP, ITGA2, NBL1 and TGM4 were down-regulated in the prostate carcinoma glands compared to the corresponding normal glands, whereas TFF3, TMPRSS2 and ERG were up-regulated. Our findings indicate that these genes may play roles as tumor suppressor genes or oncogenes in PCA, and may serve as potential tumor markers and novel therapeutic targets.     

The role of molecular biology in detection and monitoring of prostate cancer

The study of molecular markers in various types of human carcinomas, as well as in carcinoma of prostate, is focused on genes responsible for the formation of carcinoma. Mutation, amplification or other changes in these genes or in their protein products are being examined and compared with traditional prognostic markers. These genes can be characterized as oncogenes, tumor suppressor genes or genes for other significant cell functions. However, studies are often limited by heterogenity and multifocality of tumors, especially in prostate cancer. In this review, we offer a survey of some of the most frequent diagnostic and prognostic parameters of molecular biology research in relation to prostate cancer.     

Alterations of cell cycle-regulatory genes in prostate cancer.

Deregulated proliferation is one of the main events in neoplastic transformation, and this has prompted increased attention being given to the understanding of the mechanisms involved in cell cycle regulation and its alterations. The 'retinoblastoma pathway', a key effector controlling G1-S phase transition, includes several oncogenes and tumour suppressor genes which display a wide range of abnormalities with potential usefulness as markers of evolution or treatment response in prostate cancer. Among these, the existence of p53 mutations seems to predict resistance to radiotherapy or systemic treatment, and p16 overexpression or p27 downregulation seems to serve as markers of poor evolution. The well-established existence of a critical hormonal role in prostate carcinogenesis coupled with the relationship of androgenic activity and regulation of several cell cycle modulators forces cell cycle control in the prostate to be envisioned as a highly complex steroid-influenced system, which will undoubtedly have critical implications in the future management of prostate cancer patients.     

Expression of myopodin induces suppression of tumor growth and metastasis

Myopodin was previously reported as a gene that was frequently deleted in prostate cancer. This gene shares significant homology with a cell shape-regulating gene, synaptopodin. Myopodin was shown to bind actin and to induce actin bundling when cells were stimulated. To clarify the functional role of myopodin in prostate cancer, several assays were performed to evaluate the tumor suppression activity of myopodin. Our results indicate that myopodin inhibits tumor growth and invasion both in vitro and in vivo. The activity of tumor suppression of myopodin is located at the C-terminus region. To further evaluate the role of myopodin in suppressing the invasiveness of prostate cancer, an expression analysis of myopodin protein was performed in prostate tissues. The results indicate that down-regulation of myopodin expression occurs mostly in invasive stages of prostate cancer, implying a potential invasion suppression role for myopodin in prostate cancer. In addition, hemizygous deletion and down-regulation of myopodin expression occur in three aggressive prostate cancer cell lines. All these results support the hypothesis that myopodin functions as a tumor suppressor gene to limit the growth and to inhibit the metastasis of cancer cells.     

Chromosome 18 suppresses the tumorigenicity of prostate cancer cells

Microcell-mediated chromosome transfer allows for the introduction of normal chromosomes into tumor cells in an effort to identify putative tumor suppressor genes. We have used this approach to introduce an intact copy of chromosome 18 into the prostate cancer cell line DU145, and independently to introduce human chromosomes 8 and 18 into the prostate cancer cell line TSU-PR1. Introduction of an extra copy of human chromosome 8 had no effect on the growth properties in vitro or the tumorigenicity in vivo of TSU-PR1 cells. However, microcell hybrids containing an introduced copy of human chromosome 18 exhibited a longer population doubling time, retarded growth in soft agar, and slowed tumor growth in athymic nude mice. These experiments provide functional evidence for the presence of one or more tumor suppressor genes on human chromosome 18 that are involved in prostate cancer.     

Expression of oncogenes and tumor suppressor genes in human hepatocellular carcinoma and hepatoblastoma cell lines.

The expression of nine oncogenes (c-myc, N-myc, N-ras, H-ras, k-ras, abl, fos, src, and raf) and two tumor suppressor genes (p53 and RB) were studied by northern blot hybridization in six human hepatocellular carcinoma or hepatoblastoma cell lines (PLC/PRF/5, Hep3B, Hep G2, 2.2.15, HLE, and HLF) and in a human embryonic lung fibroblast cell line (WI-38) to look for differences that might be associated with the presence (PLC/PRF/5, Hep3B, and 2.2.15) or absence (Hep G2, HLE, and HLF) of integrated hepatitis B virus (HBV) DNA. The levels of expression of the oncogenes and tumor suppressor genes were unrelated to the presence or absence of integrated HBV-DNA. Furthermore, the intensity of expression of these oncogenes was no greater in the 2.2.15 cell line (consisting of Hep G2 cells transfected with hepatitis B virus) than in untransfected Hep G2 cells.     

Significance of IL-6 in the transition of hormone-resistant prostate cancer and the induction of myeloid-derived suppressor cells

Hormone-resistant (HR) prostate cancers are highly aggressive and respond poorly to treatment. A better understanding of the molecular mechanisms involved in HR should lead to more rational approaches to therapy. The role of IL-6/STAT3 signaling in the transition of HR with aggressive tumor behavior and its possible link with myeloid-derived suppressor cells (MDSCs) were identified. In the present study, murine prostate cancer cell line (TRAMP-C1) and a hormone-resistant cell sub-line (TRAMP-HR) were used. Changes in tumor growth, invasion ability, and the responsible pathway were investigated in vitro and in vivo. We also examined the role of IL-6 in HR tumor progression and the recruitment of MDSCs. As seen in both in vitro and in vivo experiments, HR had aggressive tumor growth compared to TRAMP-C1. From mRNA and protein analysis, a higher expression of IL-6 associated with a more activated STAT3 was noted in HR tumor. When IL-6 signaling in prostate cancer was blocked, aggressive tumor behavior could be overcome. The underlying changes included decreased cell proliferation, less epithelial–mesenchymal transition, and decreased STAT3 activation. In addition to tumor progression, circulating IL-6 levels were significantly correlated with MDSC recruitment in vivo. Inhibition of IL-6 abrogated the recruitment of MDSCs in tumor- bearing mice, associated with slower tumor growth and attenuated angiogenesis. In conclusion, altered IL-6/STAT3 signaling is crucial in HR transition, aggressive behavior, and MDSC recruitment. These findings provide evidence for therapeutically targeting IL-6 signaling in prostate cancer.     

Metabolism and brain cancer

Cellular energy metabolism is one of the main processes affected during the transition from normal to cancer cells, and it is a crucial determinant of cell proliferation or cell death. As a support for rapid proliferation, cancer cells choose to use glycolysis even in the presence of oxygen (Warburg effect) to fuel macromolecules for the synthesis of nucleotides, fatty acids, and amino acids for the accelerated mitosis, rather than fuel the tricarboxylic acid cycle and oxidative phosphorylation. Mitochondria biogenesis is also reprogrammed in cancer cells, and the destiny of those cells is determined by the balance between energy and macromolecule supplies, and the efficiency of buffering of the cumulative radical oxygen species. In glioblastoma, the most frequent and malignant adult brain tumor, a metabolic shift toward aerobic glycolysis is observed, with regulation by well known genes as integrants of oncogenic pathways such as phosphoinositide 3-kinase/protein kinase, MYC, and hypoxia regulated gene as hypoxia induced factor 1. The expression profile of a set of genes coding for glycolysis and the tricarboxylic acid cycle in glioblastoma cases confirms this metabolic switch. An understanding of how the main metabolic pathways are modified by cancer cells and the interactions between oncogenes and tumor suppressor genes with these pathways may enlighten new strategies in cancer therapy. In the present review, the main metabolic pathways are compared in normal and cancer cells, and key regulations by the main oncogenes and tumor suppressor genes are discussed. Potential therapeutic targets of the cancer energetic metabolism are enumerated, highlighting the astrocytomas, the most common brain cancer.     

Voltage-gated Na+ channels confer invasive properties on human prostate cancer cells

Prostate cancer is the second leading cause of cancer deaths in American males, resulting in an estimated 37,000 deaths annually, typically the result of metastatic disease. A consequence of the unsuccessful androgen ablation therapy used initially to treat metastatic disease is the emergence of androgen-insensitive prostate cancer, for which there is currently no prescribed therapy. Here, three related human prostate cancer cell lines that serve as a model for this dominant form of prostate cancer metastasis were studied to determine the correlation between voltage-gated sodium channel expression/function and prostate cancer metastatic (invasive) potential: the non-metastatic, androgen-dependent LNCaP LC cell line and two increasingly tumorogenic, androgen-independent daughter cell lines, C4 and C4-2. Fluorometric in vitro invasion assays indicated that C4 and C4-2 cells are more invasive than LC cells. Immunoblot analysis showed that voltage-gated sodium channel expression increases with the invasive potential of the cell line, and this increased invasive potential can be blocked by treatment with the specific voltage-gated sodium channel inhibitor, tetrodotoxin (TTX). These data indicate that increased voltage-gated sodium channel expression and function are necessary for the increased invasive potential of these human prostate cancer cells. When the human adult skeletal muscle sodium channel Na_v1.4 was expressed transiently in each cell line, there was a highly significant increase in the numbers of invading LC, C4, and C4-2 cells. This increased invasive potential was reduced to control levels by treatment with TTX. These data are the first to indicate that the expression of voltage-gated sodium channels alone is sufficient to increase the invasive potential of non-metastatic (LC cells) as well as more aggressive cells (i.e., C4 and C4-2 cells). Together, the data suggest that increased voltage-gated sodium channel expression alone is necessary and sufficient to increase the invasive potential of a set of human prostate cancer cell lines that serve as a model for prostate cancer metastasis.     

p16和p27表达对前列腺癌细胞系的作用

目的 探讨p16和p27Kip1 基因蛋白对抑制前列腺癌细胞增殖和调控其凋亡的作用.方法 构建携带人P16和p27基因的腺病毒载体,转染体外培养的前列腺癌细胞系PC-3,采用RT-PCR、Western blot检测目的 基因的表达.通过细胞生长试验、流式细胞仪检测PC-3转染前后细胞增殖和凋亡的变化.结果 病毒滴度Ad-p16为115×10^8 pfuPml 、Ad-p27为112×10^9 pfuPml ,RT-PCR 检测可见p16-mRNA（520bp）和p27Kip12mRNA （320bp）表达,Western blot检测有p16 蛋白（65KD）和P27蛋白（27KD） 特异表达,并可明显抑制PC-3细胞的增殖,诱导其凋亡,联合基因治疗组与单基因组相比差异显著（P＜0.01）.结论 p16和p27可明显抑制前列腺癌细胞株PC-3的增殖,增加细胞的凋亡,转染携带p16和p27的重组腺病毒载体有望成为治疗前列腺癌的有效方法.     

Epidermal growth factor induces p38 MAPK-dependent G0/G1-to-S transition in prostate cancer cells upon androgen deprivation conditions

Epidermal growth factor (EGF) is thought to contribute to the emergence of castration-resistant (CR) prostate tumors by inducing proliferation of cancer cells despite the low levels of circulating androgens achieved by androgen deprivation therapy. We show that, in LNCaP cells, androgen deprivation induces arrest in the G₀/G₁ cell cycle phase, and that EGF partially rescues this arrest without affecting cell death. Inhibition of p38 MAPK, but not MEK or IKK-β, completely abrogates the EGF-induced proliferation of LNCaP cells in androgen-depleted medium, and decreases the fraction of G₀/G₁-arrested cells. Our results suggest that EGF enables prostate cancer cells to overcome the growth restriction imposed by androgen deprivation by stimulating G₀/G₁-to-S transition via p38 MAPK. These results suggest the potential of developing therapies for advanced prostate cancer that block the G₀/G₁ to S transition, such as by targeting p38 MAPK, or that aim to induce apoptosis in G₀/G₁-arrested cancer cells.