Prostate cancer is the most common cancer in aging men. Despite recent progress, there are still few effective treatments to cure its aggressive and metastatic stages. A better understanding of the molecular mechanisms driving disease initiation and progression appears essential to support the development of more efficient therapies and improve patient care. To do so, multiple research models, such as cell culture and mouse models, have been developed over the years and have improved our comprehension of the biology of the disease. Recently, a new model has been added with the use of the Drosophila accessory gland. With a high level of conservation of major signaling pathways implicated in human disease, this functional equivalent of the prostate represents a powerful, inexpensive, and rapid in vivo model to study epithelial carcinogenesis. The purpose of this review is to quickly overview the existing prostate cancer models, including their strengths and limitations. In particular, we discuss how the Drosophila accessory gland can be integrated as a convenient complementary model by bringing new understanding in the mechanisms driving prostate epithelial tumorigenesis, from initiation to metastatic formation.

Epidemiological studies point to cholesterol as a possible key factor for both prostate cancer incidence and progression. It could represent a targetable metabolite as the most aggressive tumors also appear to be sensitive to therapies designed to decrease hypercholesterolemia, such as statins. However, it remains unknown whether and how cholesterol, through its dietary uptake and its metabolism, could be important for early tumorigenesis. Oncogene clonal induction in the Drosophila melanogaster accessory gland allows us to reproduce tumorigenesis from initiation to early progression, where tumor cells undergo basal extrusion to form extra-epithelial tumors. Here we show that these tumors accumulate lipids, and especially esterified cholesterol, as in human late carcinogenesis. Interestingly, a high-cholesterol diet has a limited effect on accessory gland tumorigenesis. On the contrary, cell-specific downregulation of cholesterol uptake, intracellular transport, or metabolic response impairs the formation of such tumors. Furthermore, in this context, a high-cholesterol diet suppresses this impairment. Interestingly, expression data from primary prostate cancer tissues indicate an early signature of redirection from cholesterol de novo synthesis to uptake. Taken together, these results reveal that during early tumorigenesis, tumor cells strongly increase their uptake and use of dietary cholesterol to specifically promote the step of basal extrusion. Hence, these results suggest the mechanism by which a reduction in dietary cholesterol could lower the risk and slow down the progression of prostate cancer.

Prostate cancer (PCa) is one of the most common cancers in men. Metastasis is the leading cause of death in prostate cancer patients. One of the crucial processes involved in metastatic spread is the “epithelial–mesenchymal transition” (EMT), which allows cells to acquire the ability to invade distant organs. Liver X Receptors (LXRs) are nuclear receptors that have been demonstrated to regulate EMT in various cancers, including hepatic cancer. Our study reveals that the LXR pathway can control pro-invasive cell capacities through EMT in prostate cancer, employing ex vivo and in vivo approaches. We characterized the EMT status of the commonly used LNCaP, DU145, and PC3 prostate cancer cell lines through molecular and immunohistochemistry experiments. The impact of LXR activation on EMT function was also assessed by analyzing the migration and invasion of these cell lines in the absence or presence of an LXR agonist. Using in vivo experiments involving NSG-immunodeficient mice xenografted with PC3-GFP cells, we were able to study metastatic spread and the effect of LXRs on this process. LXR activation led to an increase in the accumulation of Vimentin and Amphiregulin in PC3. Furthermore, the migration of PC3 cells significantly increased in the presence of the LXR agonist, correlating with an upregulation of EMT. Interestingly, LXR activation significantly increased metastatic spread in an NSG mouse model. Overall, this work identifies a promoting effect of LXRs on EMT in the PC3 model of advanced prostate cancer.

Gonadotropin injections used to stimulate oocyte production during assisted reproductive technology (ART) procedures are associated with the risk of an abnormal response in predisposed patients suffering polycystic ovary syndrome (PCOS). Liver X receptors (LXR) pathway has been identified as key regulators during this process. This study explores the integration of the hormonal signals, cellular networks and molecular mechanisms linking sterol signaling with inflammation and immune infiltration. Pharmacological activation of LXR in a wild-type context protects against gonadotropin hyperstimulation mirroring the effect observed in LXR-deficient mice. Ovarian stimulation leads to immune cell infiltration orchestrated by granulosa cells in absence of LXR, resulting in an altered granulosa cell response to gonadotropin and enhanced inflammation. LXR controls inflammasome activity by regulating Thioredoxin Interacting Protein (TXNIP) gene expression in mural granulosa cells, thereby modulating IL1β production. This immune cell infiltration persists throughout ovulation in PCOS patients and is observed in cumulus oocytes complexes, highlighting the pivotal role of LXR path in regulating inflammatory processes during hormonal stimulation in ART procedures.

Epidemiological studies point cholesterol as a possible key factor for both prostate cancer incidence and progression. So, it could represent a targetable metabolite as the most aggressive tumors also appear to be sensitive to therapies designed to decrease hypercholesterolemia, such as statins. However, whether and how cholesterol, through its dietary uptake and its metabolism, could be important for early tumorigenesis, remains unknown. Oncogene clonal induction in Drosophila melanogaster accessory gland allows to reproduce tumorigenesis from initiation to early progression, where tumour cells undergo basal extrusion to form extra-epithelial tumors. Here we show that these tumors accumulate lipids, and especially esterified cholesterol, as in human late carcinogenesis. Interestingly, high cholesterol diet displays limited effect on accessory gland tumorigenesis. On the contrary, cell-specific downregulation of cholesterol uptake, intracellular transport or metabolic response, impairs the formation of such tumors. Furthermore, in this context, high cholesterol diet suppresses this impairment. Taken together, these results reveal that during early tumorigenesis, tumour cells strongly increase their uptake and use of dietary cholesterol to specifically promote the step of basal extrusion. Interestingly, expression data from primary prostate cancer tissues indicate an early signature of redirection from cholesterol de novo synthesis to uptake. Altogether, these results suggest by which mechanism reduction of dietary cholesterol could lower the risk and slow down the progression of prostate cancer.