Meaghan L. Douglas

Hypermethylation of the 5' CpG island of the gene encoding the serine protease Testisin promotes its loss in testicular tumorigenesis.

The Testisin gene (PRSS21) encodes a glycosylphosphatidylinositol (GPI)-linked serine protease that exhibits testis tissue-specific expression. Loss of Testisin has been implicated in testicular tumorigenesis, but its role in testis biology and tumorigenesis is not known. Here we have investigated the role of CpG methylation in Testisin gene inactivation and tested the hypothesis that Testisin may act as a tumour suppressor for testicular tumorigenesis. Using sequence analysis of bisulphite-treated genomic DNA, we find a strong relationship between hypermethylation of a 385 bp 5′ CpG rich island of the Testisin gene, and silencing of the Testisin gene in a range of human tumour cell lines and in 100% (eight/eight) of testicular germ cell tumours. We show that treatment of Testisin-negative cell lines with demethylating agents and/or a histone deacetylase inhibitor results in reactivation of Testisin gene expression, implicating hypermethylation in Testisin gene silencing. Stable expression of Testisin in the Testisin-negative Tera-2 testicular cancer line suppressed tumorigenicity as revealed by inhibition of both anchorage-dependent cell growth and tumour formation in an SCID mouse model of testicular tumorigenesis. Together, these data show that loss of Testisin is caused, at least in part, by DNA hypermethylation and histone deacetylation, and suggest a tumour suppressor role for Testisin in testicular tumorigenesis.

Altered messenger RNA and protein expressions for insulin-like growth factor family members in clear cell and papillary renal cell carcinomas

Abstract Background:  The purpose of the present paper was to describe the pattern of expression of insulin‐like growth factor (IGF‐I) and its regulatory binding proteins (IGFBP) in renal cell carcinoma (RCC).

Renal cell carcinoma may adapt to and overcome anti-angiogenic intervention with thalidomide.

Objective To report on the failure of thalidomide to inhibit tumour growth in an animal model of human renal cell carcinoma (RCC).

Testicular germ cell tumors exhibit evidence of hormone dependence.

The aim of this investigation was to test the hypothesis that testicular germ cell tumors (TGCTs) are hormone‐dependent cancers. Human TGCT cells were implanted in the left testis of male severe combined immunodeficient mice receiving either no treatment or hormone manipulation treatment [blockade of gonadotropin‐releasing hormone secretion and/or signaling using leuprolide or leuprolide plus exogenous testosterone]. Real‐time RT‐PCR analysis was used to determine the expression profiles of hormone pathway‐associated genes. Tumor burden was significantly smaller in mice receiving both leuprolide and testosterone. Real‐time RT‐PCR analysis of follicle‐stimulating hormone (FSH) receptor, luteinizing hormone (LH) receptor and P450 aromatase revealed changes in expression in normal testis tissue related to presence of xenograft tumors and manipulation of hormone levels but a complete absence of expression of these genes in tumor cells themselves. This was confirmed in human specimens of TGCT. Reduced TGCT growth in vivo was associated with significant downregulation of LH receptor and P450 aromatase expression in normal testes. In conclusion, manipulation of hormone levels influenced the growth of TGCT in vivo, while the presence of xenografted tumors influenced the expression of hormone‐related genes in otherwise untreated animals. Human TGCTs, both in the animal model and in clinical specimens, appear not to express receptors for FSH or LH. Similarly, expression of the P450 aromatase gene is absent in TGCTs. Impaired estrogen synthesis and/or signaling may be at least partly responsible for inhibition of TGCT growth in the animal model.

An orthotopic xenograft model of human nonseminomatous germ cell tumour

We have established the first example of an orthotopic xenograft model of human nonseminomatous germ cell tumour (NSGCT). This reproducible model exhibits many clinically relevant features including metastases to the retroperitoneal lymph nodes and lungs, making it an ideal tool for research into the development and progression of testicular germ cell tumours.

Models of Human Renal Cell Carcinoma

The dynamic and complex processes involved in tumor growth and progression are difficult to study merely by analysis of clinical specimens. Detailed investigations of the effects of tumor cytokine pathways, particularly in relation to cell cycle and function and tumor/host interactions, including metastasis, angiogenesis, and immunological responses, require model systems that can be controlled and manipulated. These systems are also often necessary to determine the effects and safety of therapeutic strategies before translation into clinical practice.