Prostate cancer is a multifactorial disease with worldwide impact. Both the rise in the life expectancy of the general population and the growing public awareness and use of the screening methods available for the disease, particularly PSA, have greatly contributed to changing the typical prostate cancer patient’s profile from that of 50 years ago. Prostate cancer was usually diagnosed only at an advanced stage due to metastatic disease and the diagnosis was seen as a death sentence in 1-2 years. Nowadays, the disease can be diagnosed in its early stages and it is potentially curable by surgical or radiological approaches. Prostate cancer management and treatment options are currently considered in face of the stage of the disease, the patient’s life expectancy, the adverse effects’ profile of the available therapeutic options and patient preference. Hormonal treatments for prostate cancer therapy are based on the Nobel Prize winner discovery by Huggins et al., in 1941, that the growth and progression of prostate cancer cells depends on androgen levels in the body. CYP17 is one of the enzymes involved in androgen biosynthesis in the human body. Its inhibition has tradicionally been recognized as an important strategy for prostate cancer treatment as a way to lower androgen levels and thus stop disease progression. Ketoconazole, a non steroidal antifungal compound which was reported to cause gynecomastia in male patients, was the first to be used clinically for prostate cancer treatment. After ketoconazole, a series of compounds, both steroidal and non steroidal, have been synthesized and evaluated as CYP17 inhibitors in the hope of finding more potent molecules with a better side effects’ profile. The aim of the present work was to synthesize new steroidal compounds bearing the androstane backbone, which correlated well with the known structure-activity dispositions currently accepted for CYP17 inhibitors, and would thus contribute to prostate cancer treatment. Two different synthetic strategies have been exploited which resulted in the preparation of two sets of compounds generally designated as indazole derivatives and C17 2’-methylimidazole derived carbamates. The structural elucidation of these novel compounds was performed based on IR, mass spectrometry and 1H and 13C NMR 1D and 2D techniques. The synthesized indazole derivatives, alike other steroidal compounds which have been found to be good CYP17 inhibitors, possess not only an heterocyclic moiety with available electrons capable of coordination with the heme Fe of the enzime, but also a C16 double bond. In the synthesized C17 2’-methylimidazole derived carbamates, the carbamate function acts as a spacer group, increasing the distance between the heterocyclic moiety and C17. Only two of the synthesized C17 2’-methylimidazole derived carbamates inhibited the human CYP17 enzyme, however less potently than ketoconazole. The indazole derivatives were found to be non-inhibitory. Possible reasons for this occurrence have been presented. Blockage of androgen receptor function is also a fundamental strategy for prostate cancer treatment because disease progression is intimately related to it. Both the rise in the number of available receptors and the presence of mutated receptors have been reported as important for the development of resistance to very low androgen levels in the body, thus making the previously mentioned therapeutic strategies ineffective. The fact that compounds which were designed as CYP17 inhibitors have been reported to antagonize the androgen receptor and inhibit androgen receptor mediated transcription, has opened a new chapter in the pre-clinical assessment of this type of compounds. In the face of this new context, the affinity of the indazole derivatives and the C17 2’-methylimidazole derived carbamates, towards both the original and the mutated the androgen receptor, using metastatic prostate cancer cell lines such as LAPC4 and LNCaP, was also studied. The effect of these novel compounds on mutated androgen receptor mediated transcription (on LNCaP cells), both in the presence and absence of the natural ligand dihydrotestosterone, was evaluated using the luciferase reporter assay. In general, the C17 2’-methylimidazole derived carbamates bound to the androgen receptor with excelent affinity. Their effect on mutated androgen receptor mediated transcription was found to be concentration dependent. The indazole derivatives did not display good affinity towards the androgen receptor. The ability to inhibit prostate cancer cell line proliferation (LAPC4, LNCaP and PC-3 cells) was studied for the new synthesized compounds based on the reduction of formazan salts. Both groups of compounds were particularly effective in inhibiting the proliferation of PC-3 cells which do not express the androgen receptor, and thus represent a model of study for the more advanced stages of prostate cancer.
|Place of Publication||Portugal|
|Publication status||Published - 2008|
- prostate cancer
- cancer screening