Shian Ying Sung

Radiation modulation of microRNA in prostate cancer cell lines

MicroRNAs (miRNA) are gene regulators and play an important role in response to cellular stress.

Coevolution of Prostate Cancer and Bone Stroma in Three-Dimensional Coculture: Implications for Cancer Growth and Metastasis

Human bone stromal cells, after three-dimensional coculture with human prostate cancer (PCa) cells in vitro, underwent permanent cytogenetic and gene expression changes with reactive oxygen species serving as mediators. The evolved stromal cells are highly inductive of human PCa growth in mice, and expressed increased levels of extracellular matrix (versican and tenascin) and chemokine (BDFN, CCL5, CXCL5, and CXCL16) genes. These genes were validated in clinical tissue and/or serum specimens and could be the predictors for invasive and bone metastatic PCa. These results, combined with our previous observations, support the concept of permanent genetic and behavioral changes of PCa epithelial cells after being either cocultured with prostate or bone stromal cells as three-dimensional prostate organoids or grown as tumor xenografts in mice. These observations collectively suggest coevolution of cancer and stromal cells occurred under three-dimensional growth condition, which ultimately accelerates cancer growth and metastasis.

Oxidative Stress Induces ADAM9 Protein Expression in Human Prostate Cancer Cells

The ADAM (a disintegrin and metalloprotease) family is a group of transmembrane proteins containing cell adhesive and proteolytic functional domains. Microarray analysis detected elevated ADAM9 during the transition of human LNCaP prostate cancer cells from an androgen-dependent to an androgen-independent and metastatic state. Using a prostate tissue array (N = 200), the levels of ADAM9 protein expression were also elevated in malignant as compared with benign prostate tissues. ADAM9 protein expression was found in 43% of benign glands with light staining and 87% of malignant glands with increasing intensity of staining. We found that ADAM9 mRNA and protein expressions were elevated on exposure of human prostate cancer cells to stress conditions such as cell crowding, hypoxia, and hydrogen peroxide. We uncovered an ADAM9-like protein, which is predominantly induced together with the ADAM9 protein by a brief exposure of prostate cancer cells to hydrogen peroxide. Induction of ADAM9 protein in LNCaP or C4-2 cells can be completely abrogated by the administration of an antioxidant, ebselen, or genetic transfer of a hydrogen peroxide degradative enzyme, catalase, suggesting that reactive oxygen species (ROS) are a common mediator. The induction of ADAM9 by stress can be inhibited by both actinomycin D and cycloheximide through increased gene transcription and protein synthesis. In conclusion, intracellular ROS and/or hydrogen peroxide, generated by cell stress, regulate ADAM9 expression. ADAM9 could be responsible for supporting prostate cancer cell survival and progression. By decreasing ADAM9 expression, we observed apoptotic cell death in prostate cancer cells.

Modulation of prostate cancer growth in bone microenvironments

Bone remains one of the major sites, and most lethal host organs, for prostate cancer metastasis. Prostate cell spread and establishment in bone depends on multiple reciprocal modifications of bone stromal and epithelial cancer cell behaviors. This review focuses on recent advances in the characterization of cell–cell and cell–matrix interplay, effects on cell growth, adhesion and invasion, and several therapeutic possibilities for co‐targeting prostate cancer cells and bone stroma. We address the topic from three main perspectives: (1) the normal and aging bone stromal environment, (2) the “reactive” bone stromal environment, and (3) the cancerous prostate epithelial cells themselves. First, normal, and especially aging, bones provide uniquely rich and “fertile soil” for roaming cancer cells. The interactions between prostate cancer cells and insoluble extracellular matrices, soluble growth factors, and/or sex steroid hormones trigger bone remodeling, through increased osteoclastogenesis and furthur matrix metalloproteinase activity. Second, after cancer cell arrival and establishment in the bone, host stromal cells respond, becoming “reactive” in a process again involving extracellular matrix remodeling, together with growth factor and steroid receptor signaling this process ultimately enhances cancer cell migration, stromal transdifferentiation, and invasion of the cancer tissues by stromal, inflammatory, and immune‐responsive cells. Third, prostate cancer cells also respond to supportive bone microenvironments, where soluble and matrix‐associated molecules affect cancer cell growth and gene expression, especially altering cancer cell surface receptor and integrin‐mediated cell signaling. We discuss both integrin cell–matrix and gap junctional cell–cell communication between cancer cells and their microenvironments during prostate cancer progression.

New targets for therapy in prostate cancer: Modulation of stromal-epithelial interactions

Changes in genomic and phenotypic expression of progressing prostate tumors and their stroma occur in a dynamic fashion based on bidirectional signaling from stromal-epithelial interactions. These interactions may underlie the ability of prostate cancer cells to survive and proliferate in the prostate and bone. By investigating the phenotypic and genotypic changes of stromal cells adjacent to cancer cells and the reciprocal changes of cancer cells, novel molecular markers may be developed to diagnose cancer earlier before pathologic appearance of cancer cells at the primary site. Attacking epithelial and stromal elements together is a unique approach to both localized and metastatic prostate cancer therapy. Co-targeting both tumor cells and stroma requires identifying a reliable tumor and tissue-specific cis-DNA element, such as osteocalcin (OC) promoter. OC expression is elevated in prostate tumor cells and in prostate and bone stromal cells interdigitating with both localized and metastatic prostate epithelium. We have previously designed an adenovirus-based therapeutic gene vehicle and demonstrated that a replication-competent adenoviral vector (Ad vector) is highly efficient in blocking the growth of cancer cells in culture, including cells without androgen receptor as well as cells that do or do not make prostate-specific antigen. In vivo, intravenous administration of an Ad-OC vector was effective against preexisting human prostate cancer subcutaneous and bone xenografts. The addition of vitamin D(3) enhanced further viral replication at target sites. Co-targeting tumor cells and stroma using systemic Ad vector is a viable and promising option for treatment of both localized and metastatic prostate cancer.

Inhibition of ADAM9 expression induces epithelial phenotypic alterations and sensitizes human prostate cancer cells to radiation and chemotherapy.

Recent studies demonstrated the importance of ADAM9 in prostate cancer relapse upon therapy. In this study, we determined the role of ADAM9 in the therapeutic resistance to radiation and chemotherapy.

A novel targeting modality for renal cell carcinoma: human osteocalcin promoter-mediated gene therapy synergistically induced by vitamin C and vitamin D3

Advanced renal cell carcinoma (RCC) frequently develops skeletal metastasis and is highly resistant to conventional therapies. We hypothesized that the osteocalcin (OC) promoter may be a promising gene delivery system for RCC targeted gene therapy because osteotropic tumors gain osteomimetic properties and thrive in the new environment by exhibiting a bone‐like gene expression profile. Human OC (hOC) expression is highly regulated by vitamins and hormone. In the present study, we tested the feasibility of vitamin‐regulatable hOC promoter for RCC‐specific transcriptional targeting, and examined the anti‐tumor effect of vitamins C and D3 with hOC‐based adenoviral vectors towards RCC.

Exosomes from the tumor microenvironment as reciprocal regulators that enhance prostate cancer progression

Distant organ metastasis of prostate cancer is a puzzle, and various theories have successively arisen to explain the mechanism of lethal cancer progression. While perhaps agreeable to many cancer biologists, the very statement of “seed and soil” proposed by Stephan Paget in 1881 is arguably still the major statement for organ‐specific cancer metastasis. Since recent studies showed important correlations of regulation of cancer cells and the microenvironment, exosomes from cancer and stromal cells seem to create another important niche for metastasis. Stromal cells pretreated with exosomes from metastatic cancer cells increase the potential of change stromal cells. The poorly metastatic cancer cells could also enhance malignancy through transfer of proteins, microribonucleic acid and messenger ribonucleic acid to recipient cancer cells. Herein, we reviewed extracellular exosomes as a factor involved in cross‐talk between stromal and prostate cancer epithelial cells.

Combined Dynamic Alterations in Urinary VEGF Levels and Tissue ADAM9 Expression as Markers for Lethal Phenotypic Progression of Prostate Cancer

Recent evidence has demonstrated that detection of changes in the levels of urinary vascular endothelial growth factor (VEGF) and tissue a disintegrin and metalloproteinase 9 (ADAM9) is effective in determining prostate cancer progression. To evaluate the combined application of VEGF and ADAM9 as early progression markers of lethal phenotypic cancer, quantification of urinary VEGF and tissue ADAM9 expression was studied in patients with late stage prostate cancer. Tissue biopsies were collected during palliative transurethral resection of prostate (TURP) surgery, and urine samples were collected before hormone therapy and 3, 6 and 12 months post-TURP. We observed a nearly 100% correlation between increasing urinary VEGF levels over time and prostate cancer progression, but no correlation was observed when comparing urinary VEGF concentrations at a single time point and cancer progression. In addition, we also observed correlation of increasing ADAM9 nuclear positive staining and lethal phenotypic transition. Statistical analysis revealed that both the increase in urinary VEGF level and the presence of the tissue ADAM9 nuclear staining were significantly correlated with the risk of patients with relapse prostate cancer (P < 0.05). Thus, we suggest that combination of detection of changes in urinary VEGF and tissue staining of ADAM9 may be accurate for predicting the mortality of patients with prostate cancer during hormone therapy.

Co-targeting prostate cancer epithelium and bone stroma by human osteonectin- promoter-mediated suicide gene therapy effectively inhibits androgen-independent prostate cancer growth

Stromal-epithelial interaction has been shown to promote local tumor growth and distant metastasis. We sought to create a promising gene therapy approach that co-targets cancer and its supporting stromal cells for combating castration-resistant prostate tumors. Herein, we demonstrated that human osteonectin is overexpressed in the prostate cancer epithelium and tumor stroma in comparison with their normal counterpart. We designed a novel human osteonectin promoter (hON-522E) containing positive transcriptional regulatory elements identified in both the promoter and exon 1 region of the human osteonectin gene. In vitro reporter assays revealed that the hON-522E promoter is highly active in androgen receptor negative and metastatic prostate cancer and bone stromal cells compared to androgen receptor-positive prostate cancer cells. Moreover, in vivo prostate-tumor–promoting activity of the hON-522E promoter was confirmed by intravenous administration of an adenoviral vector containing the hON-522E promoter-driven luciferase gene (Ad-522E-Luc) into mice bearing orthotopic human prostate tumor xenografts. In addition, an adenoviral vector with the hON-522E-promoter–driven herpes simplex virus thymidine kinase gene (Ad-522E-TK) was highly effective against the growth of androgen-independent human prostate cancer PC3M and bone stromal cell line in vitro and in pre-established PC3M tumors in vivo upon addition of the prodrug ganciclovir. Because of the heterogeneity of human prostate tumors, hON-522E promoter-mediated gene therapy has the potential for the treatment of hormone refractory and bone metastatic prostate cancers.