Current Pharmaceutical Design - Volume 10, Issue 5, 2004

The testis is devoted to two important tasks: haploid cell production and sexual steroid synthesis. A number of highly sophisticated and unique strategies operate during spermatogenesis, a process crucial for reproduction, heredity and evolution. It is particularly important to decipher the underlying molecular mechanisms whose function can be perverted in pathological situations, such as infertility and testicular cancers, which represent an increasing biomedical issue today. This review summarises the currently available data concerning some key molecular components that are altered or potentially involved in male infertility and testicular tumors, with the aim of defining some common “hot spots”. We particularly focused on genetically engineered in vivo models in which testicular functions are altered and we pinpointed to the potential involvement of the targeted genes in testicular pathologies. Those molecular mechanisms peculiar to the male gonad can be envisioned as a basis for the design of novel drugs potentially dedicated to testicular dysfunction.

Genetic lesions causing human male infertility are manifold. Besides gross chromosomal aneuploidies and rearrangements, microdeletions and single gene defects can interfere with male fertility. Male fertility is not only dependent on genes controlling the male germ line but also on genes of the networks functional for male gonad development and male somatic development, respectively. It is popular to unravel these netweorks with mouse gene knock-out mutants displaying reproductive defects. However, substantial arguments can be given for more functional studies directly on the human genes, because multiple reproductive proteins evolve quickly most likely for adopting to the specific needs of the species class. Prominent examples are mutations of the FSHR gene causing different pathologies in mouse and human and the DAZ gene family not found in the mouse genome but in the human genome with an essential male fertility function. Therefore this review is focussed on a comprehensive overview of human genes known with mutations causing male infertility (AR; AZF gene families; CFTR, DM-1, DNAH gene family, FGFR1, FSHR, INSL3, KAL-1, LGR8- GREAT, LHR, POLG). Then some human genes are described well recognised as functional in spermatogenesis and male fertility although gene specific mutations causing infertility were not yet identified (CREM, CDY1, DAZL1, PHGPx, PRM-1, PRM-2). They are designated as “spermatogenesis phase marker” or “male fertility index” genes, because they are useful tools for diagnosing the patient‘s’ spermatogenesis disruption phase and for predicting the presence and quality of his mature sperms. Current therapeutic protocols for human male infertility do usually not cure the specific gene defect but try to bypass it using Artificial Reproductive Technology (ART). Putative imprinting defects in the early embryo probably associated with the used ART protocol and an increase of chromosome abnormalities in the ART offspring now strongly asks for a significant improvement of this outcome requesting urgently more basic research on the genes functioning in the human male germ line and during early human embryogenesis.

Sex, that is, whether one is physically male or female, is the basic dichotomy of life. Sex is important not only for reproductive role, but also for physical attributes, personal identity and disease susceptibility. Sex determination is genetically controlled, with the key event in males being the transmission of a Y chromosome from father to offspring. The sex-determining gene on the Y chromosome, SRY, triggers the expression of a repertoire of other genes that cause the undifferentiated gonad to develop as a testis. Hormones secreted by the developing testis cause the internal and external genitalia to masculinize. Testicular development is disrupted by de novo or inherited genetic alterations leading to gonadal dysgenesis. Decreased hormone production from dysgenetic testes disrupts the normal development of the internal and external genitalia. Incomplete masculinization of the genitalia also occurs from hormonal biosynthetic defects or decreased response to hormones from inherited receptor defects. Treatment is tailored to the individual diagnosis and may include removal of dysgenetic gonads, surgical correction of incompletely masculinized genitalia, replacement of deficient hormones, and, in some instances, gender reassignment.

Prostate cancer develops from clones that are already present as early as thirty-five years of age, when circulating concentrations of androgens are high. The progression of the disease is low and the cancer is diagnosed at a more advanced age. Prostate cancer evolves from an androgen dependant stage to stage where it escapes from all antiandrogenic treatments. The patient usually dies within two years following the diagnosis of advanced cancer. Therefore, it is of great interest to develop new therapies for androgen independent prostate cancer. The androgen independent evolution of prostate cancer is a complex phenomenon at the cellular and molecular levels. It includes an increased sensitivity to growth factors, the control of proliferation pathways, apoptotic and survival pathways as well as the control of angiogenesis. Epidemiological studies have also suggested that certain vitamins or phyto-oestrogens could protect against prostate cancer development. The present review attempts to present an overview of the fundamental research in cellular signalling which could be interesting as target for the treatment of androgen independent prostate cancer. Also the potential interest of non-androgenic steroids was reviewed for the same goal.

Prostate cancer is the most frequently diagnosed disease in American men today and the second leading cause of death among them. Transformation and progression towards malignancy in prostate cancer is dependant on the inability of the prostatic epithelial cells to undergo apoptosis rather than on the regulation of proliferation. Molecular targeting of inadequacies in this process of suppression of apoptosis could prove to be of great therapeutic importance for prostate cancer patients. Existence of tissue specific promoters to aid in the delivery of genes with therapeutic potential makes molecular therapy an attractive option. This review discusses salient features of molecules such as, Bcl-2, Bcl-XL, NF-kB, Akt, PTEN and Par-4 that play a significant role in the regulation of prostate cancer and focuses on the prospects of effectively utilizing their potential for the therapy of hormone-sensitive and hormone-resistant prostate cancer.

Gene therapy is rapidly emerging as a viable clinical strategy to treat prostate cancer. New developments, such as targeted expression of therapeutic genes, and viruses that are designed to selectively replicate in prostate cancer cells have led to vectors with improved safety, even in elderly male patients. This review describes the various different viral and non-viral strategies employed to date, with a summary of current clinical trials. The main focus of the review is a discussion of the need, and the potential methods that can be used for targeted expression of the therapeutic gene specifically to prostate tumours and metastases. This includes methods of abrogating vector transduction of non-specific tissues, enhancement of transduction into prostate tumour tissue, transcriptional control of the therapeutic gene and some examples of prostate cancer-specific therapeutic genes. We also consider the future of prostate cancer gene therapy and the factors that should be taken into account when designing clinical trials, in a field that is expected to impact on clinical management of a common tumour type.

Sexually transmissible diseases such as AIDS have renewed the attention paid to viruses capable of infecting the male genital tract. The presence of viruses at this level may not only lead to their transmission and spread via semen but may also impact on male fertility and / or represent a potential cause of genital organ cancers. This review summarizes the currently available data on the various viruses identified in the human semen and male reproductive tract, their distribution in tissues and fluids, their possible cell targets and the functional consequences of their infectivity on the reproductive and endocrine systems. The use of medically assisted reproduction as a therapeutic tool in serodiscordant couples, as well as treatment strategies that need to be developed in order to eradicate these viruses from the male genital tract, are discussed.