Chromosome 18 suppresses prostate cancer metastases

Bisphosphonate conjugation for bone specific drug targeting

Bones provide essential functions and are sites of unique biochemistry and specialized cells, but can also be sites of disease. The treatment of bone disorders and neoplasia has presented difficulties in the past, and improved delivery of drugs to bone remains an important goal for achieving effective treatments. Drug targeting strategies have improved drug localization to bone by taking advantage of the high mineral concentration unique to the bone hydroxyapatite matrix, as well as tissue-specific cell types. The bisphosphonate molecule class binds specifically to hydroxyapatite and inhibits osteoclast resorption of bone, providing direct treatment for degenerative bone disorders, and as emerging evidence suggests, cancer. These bone-binding molecules also provide the opportunity to deliver other drugs specifically to bone by bisphosphonate conjugation. Bisphosphonate bone-targeted therapies have been successful in treatment of osteoporosis, primary and metastatic neoplasms of the bone, and other bone disorders, as well as refining bone imaging. In this review, we focus upon the use of bisphosphonate conjugates with antineoplastic agents, and overview bisphosphonate based imaging agents, nanoparticles, and other drugs. We also discuss linker design potential and the current state of bisphosphonate conjugate research progress. Ongoing investigations continue to expand the possibilities for bone-targeted therapeutics and for extending their reach into clinical practice.

Pre-clinical mouse models of human prostate cancer and their utility in drug discovery

In vivo animal experiments are essential to current prostate cancer research, and are particularly critical to studying interactions between tumor cells and their microenvironment. Numerous pre-clinical animal models of prostate cancer are currently available, including transgenic mouse models and human prostate cancer xenograft mouse models. In contrast to transgenic mouse models producing more heterogeneous cohorts of tumors, xenograft mouse models provide more controlled approaches. This unit describes the detailed procedures necessary to establish several distinct pre-clinical mouse models of human prostate cancer, including an orthotopic prostate xenograft model, an orthotopic bone metastasis model, an experimental metastasis model of intra-cardiac injection, and a vossicle model of tumor-bone interaction.

The impact of genomic alterations on the transcriptome: a prostate cancer cell line case study

Genetic instability may lead to the loss/gain of transcriptional control. Here we investigated the effect of genomic instability, that is loss/gain of chromosomal regions on the global transcriptome of prostate cancer cell line DU145. The genomic loss/gain map obtained through BAC array-based CGH was superimposed on the dynamic transcriptome of DU145 cells treated with serum for 0 h (serum starved), 2 h and 12 h. The genomic analysis suggested that in DU145 cells: (1) chromosomal gains are prominent than losses and (2) copy number changes are associated with chromosome-specific and dynamic gene expression regulatory mechanisms. A significant proportion of the genes in the stable regions of the chromosome were up-regulated whereas a higher proportion of genes were down-regulated at 2 and 12 h in the deleted regions of the chromosomes following serum treatment. No change in expression was observed for the genes in the gained regions over a period of time. This analysis led us to propose that loss of heterozygosity leads to an overall transcriptional down-regulation that may further lead to a decrease in the expression of putative tumor suppressors. The genomic profile of DU145 is similar to pathological specimens of prostate cancer, hence the genomic/transcriptomic signature of DU145 can be used to understand the pathology of prostate cancer. It is expected that this analysis will allow a better understanding of transcriptional regulatory mechanisms in the context of genomic loss and gain and may lead to the discovery of novel oncogenes and tumor suppressors and the underlying regulatory pathways.

The human Y chromosome suppresses the tumorigenicity of PC-3, a human prostate cancer cell line, in athymic nude mice

The loss of the Y chromosome is a frequent numerical chromosomal abnormality observed in human prostate cancer. In cancer, loss of specific genetic material frequently accompanies simultaneous inactivation of tumor suppressor genes. It is not known whether the Y chromosome harbors such genes. To address the role of genes on the Y chromosome in human prostate cancer, we transferred a tagged Y chromosome into PC-3, a human prostate cancer cell line lacking a Y chromosome. A human Y chromosome was tagged with the hisD gene and transferred to PC-3 by microcell-mediated chromosome transfer. Tumorigenicity of these PC-3 hybrids was tested in vivo and in vitro, and the results were compared with those of the polymerase chain reaction analyses conducted on the PC-3 hybrids using Y chromosome-specific markers. Among 60 mice injected with 12 different PC-3 hybrids (five mice per hybrid), tumor growth was apparent in only one mouse, whereas tumors grew in all mice injected with the parental PC-3 cells. An in vitro assay showed that the Y chromosome did not suppress anchorage-independent growth of PC-3 cells. We found that addition of the Y chromosome suppressed tumor formation by PC-3 in athymic nude mice, and that this block of tumorigenesis was independent of the in vitro growth properties of the cells. This observation suggests the presence of a gene important for prostate tumorigenesis on the Y chromosome.

Chromosome 18 suppresses tumorigenic properties of human prostate cancer cells

Although prostate cancer is still the most diagnosed cancer in men, most genes implicated in its progression are yet to be identified. Chromosome abnormalities have been detected in human prostate tumors, many of them associated with prostate cancer progression. Indeed, alterations (including deletions or amplifications) of more than 15 human chromosomes have been reported in prostate cancer. We hypothesized that transferring normal human chromosomes into human prostate cancer cells would interfere with their tumorigenic and/or metastatic properties. We used microcell-mediated chromosome transfer to introduce human chromosomes 10, 12, 17, and 18 into highly tumorigenic (PC-3M-Pro4) and highly metastatic (PC-3M-LN4) PC-3-derived cell lines. We tested the in vitro and in vivo properties of these hybrids. Introducing chromosome 18 into the PC-3M-LN4 prostate cancer cell line greatly reduced its tumorigenic phenotype. We observed retarded growth in soft agar, decreased invasiveness through Matrigel, and delayed tumor growth into nude mice, both subcutaneously and orthotopically. This phenotype is associated with a marker in the 18q21 region. Combined with the loss of human chromosome 18 regions often seen in patients with advanced prostate cancer, our results show that chromosome 18 encodes one or more tumor-suppressor genes whose inactivation contributes to prostate cancer progression.