TMPRSS2-ERG fusion promotes prostate cancer metastases in bone

International audienceBone metastasis is the major deleterious event in prostate cancer (PCa). TMPRSS2-ERG fusion is one of the most common chromosomic rearrangements in PCa. However, its implication in bone metastasis development is still unclear. Since bone metastasis starts with the tropism of cancer cells to bone through specific migratory and invasive processes involving osteomimetic capabilities, it is crucial to better our understanding of the influence of TMPRSS2-ERG expression in the mechanisms underlying the bone tropism properties of PCa cells. We developed bioluminescent cell lines expressing the TMPRSS2-ERG fusion in order to assess its role in tumor growth and bone metastasis appearance in a mouse model. First, we showed that the TMPRSS2-ERG fusion increases cell migration and subcutaneous tumor size. Second, using intracardiac injection experiments in mice, we showed that the expression of TMPRSS2-ERG fusion increases the number of metastases in bone. Moreover, TMPRSS2-ERG affects the pattern of metastatic spread by increasing the incidence of tumors in hind limbs and spine, which are two of the most frequent sites of human PCa metastases. Finally, transcriptome analysis highlighted a series of genes regulated by the fusion and involved in the metastatic process. Altogether, our work indicates that TMPRSS2-ERG increases bone tropism of PCa cells and metastasis development

TMPRSS2:ERG gene fusion expression regulates bone markers and enhances the osteoblastic phenotype of prostate cancer bone metastases

International audienceAbstract : Prostate cancers have a strong propensity to metastasize to bone and promote osteoblastic lesions. TMPRSS2:ERG is the most frequent gene rearrangement identified in prostate cancer, but whether it is involved in prostate cancer bone metastases is largely unknown. We exploited an intratibial metastasis model to address this issue and we found that ectopic expression of the TMPRSS2:ERG fusion enhances the ability of prostate cancer cell lines to induce osteoblastic lesions by stimulating bone formation and inhibiting the osteolytic response. In line with these in vivo results, we demonstrate that the TMPRSS2:ERG fusion protein increases the expression of osteoblastic markers, including Collagen Type I Alpha 1 Chain and Alkaline Phosphatase, as well as Endothelin-1, a protein with a documented role in osteoblastic bone lesion formation. Moreover, we determined that the TMPRSS2:ERG fusion protein is bound to the regulatory regions of these genes in prostate cancer cell lines, and we report that the expression levels of these osteoblastic markers are correlated with the expression of the TMPRSS2:ERG fusion in patient metastasis samples. Taken together, our results reveal that the TMPRSS2:ERG gene fusion is involved in osteoblastic lesion formation induced by prostate cancer cells

L'infection par le SARS-CoV-2 induit des lésions persistantes du tissu adipeux chez les hamsters syriens dorés âgés.

International audienceCoronavirus disease 2019 (COVID-19, caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2)) is primarily a respiratory illness. However, various extrapulmonary manifestations have been reported in patients with severe forms of COVID-19. Notably, SARS-CoV-2 was shown to directly trigger white adipose tissue (WAT) dysfunction, which in turn drives insulin resistance, dyslipidemia, and other adverse outcomes in patients with COVID-19. Although advanced age is the greatest risk factor for COVID-19 severity, published data on the impact of SARS-CoV-2 infection on WAT in aged individuals are scarce. Here, we characterized the response of subcutaneous and visceral WAT depots to SARS-CoV-2 infection in young adult and aged golden hamsters. In both age groups, infection was associated with a decrease in adipocyte size in the two WAT depots; this effect was partly due to changes in tissue’s lipid metabolism and persisted for longer in aged hamsters than in young-adult hamsters. In contrast, only the subcutaneous WAT depot contained crown-like structures (CLSs) in which dead adipocytes were surrounded by SARS-CoV-2-infected macrophages, some of them forming syncytial multinucleated cells. Importantly, older age predisposed to a unique manifestation of viral disease in the subcutaneous WAT depot during SARS-CoV-2 infection; the persistence of very large CLSs was indicative of an age-associated defect in the clearance of dead adipocytes by macrophages. Moreover, we uncovered age-related differences in plasma lipid profiles during SARS-CoV-2 infection. These data suggest that the WAT’s abnormal response to SARS-CoV-2 infection may contribute to the greater severity of COVID-19 observed in elderly patients.La maladie à coronavirus 2019 (COVID-19, causée par le syndrome respiratoire aigu sévère-coronavirus 2 (SRAS-CoV-2)) est principalement une maladie respiratoire. Cependant, diverses manifestations extrapulmonaires ont été signalées chez des patients atteints de formes graves de COVID-19. Il a notamment été démontré que le SRAS-CoV-2 déclenche directement le dysfonctionnement du tissu adipeux blanc (TAC), qui entraîne à son tour une résistance à l'insuline, une dyslipidémie et d'autres effets indésirables chez les patients atteints de COVID-19. Bien que l'âge avancé soit le facteur de risque le plus important pour la gravité de la COVID-19, les données publiées sur l'impact de l'infection par le SRAS-CoV-2 sur le tissu adipeux des personnes âgées sont rares. Nous avons caractérisé ici la réponse des dépôts de WAT sous-cutanés et viscéraux à l'infection par le SRAS-CoV-2 chez des hamsters dorés jeunes adultes et âgés. Dans les deux groupes d'âge, l'infection a été associée à une diminution de la taille des adipocytes dans les deux dépôts de WAT ; cet effet était en partie dû à des changements dans le métabolisme des lipides du tissu et a persisté plus longtemps chez les hamsters âgés que chez les jeunes adultes. En revanche, seul le dépôt de WAT sous-cutané contenait des structures en forme de couronne (CLS) dans lesquelles les adipocytes morts étaient entourés de macrophages infectés par le SRAS-CoV-2, certains d'entre eux formant des cellules syncytiales multinucléées. Il est important de noter que l'âge avancé prédisposait à une manifestation unique de la maladie virale dans le dépôt sous-cutané de WAT pendant l'infection par le SRAS-CoV-2 ; la persistance de très grandes CLSs indiquait un défaut associé à l'âge dans l'élimination des adipocytes morts par les macrophages. De plus, nous avons mis en évidence des différences liées à l'âge dans les profils lipidiques plasmatiques au cours de l'infection par le SRAS-CoV-2. Ces données suggèrent que la réponse anormale du WAT à l'infection par le SRAS-CoV-2 peut contribuer à la plus grande sévérité du COVID-19 observée chez les patients âgés

Increased Adipogenesis in Cultured Embryonic Chondrocytes and in Adult Bone Marrow of Dominant Negative Erg Transgenic Mice

<div><p>In monolayer culture, primary articular chondrocytes have an intrinsic tendency to lose their phenotype during expansion. The molecular events underlying this chondrocyte dedifferentiation are still largely unknown. Several transcription factors are important for chondrocyte differentiation. The Ets transcription factor family may be involved in skeletal development. One family member, the <em>Erg</em> gene, is mainly expressed during cartilage formation. To further investigate the potential role of Erg in the maintenance of the chondrocyte phenotype, we isolated and cultured chondrocytes from the rib cartilage of embryos of transgenic mice that express a dominant negative form of Erg (DN-Erg) during cartilage formation. DN-Erg expression in chondrocytes cultured for up to 20 days did not affect the early dedifferentiation usually observed in cultured chondrocytes. However, lipid droplets accumulated in DN-Erg chondrocytes, suggesting adipocyte emergence. Transcriptomic analysis using a DNA microarray, validated by quantitative RT-PCR, revealed strong differential gene expression, with a decrease in chondrogenesis-related markers and an increase in adipogenesis-related gene expression in cultured DN-Erg chondrocytes. These results indicate that Erg is involved in either maintaining the chondrogenic phenotype <em>in vitro</em> or in cell fate orientation. Along with the <em>in vitro</em> studies, we compared adipocyte presence in wild-type and transgenic mice skeletons. Histological investigations revealed an increase in the number of adipocytes in the bone marrow of adult DN-Erg mice even though no adipocytes were detected in embryonic cartilage or bone. These findings suggest that the Ets transcription factor family may contribute to the homeostatic balance in skeleton cell plasticity.</p> </div

Histological examination of 18.5 day-old embryos.

<p>A. Skeletal and cartilage preparations of wt (left) and DN-Erg (right) mice at E18.5. Cartilage stained with Alcian blue, bone with Alizarin red. DN-Erg E18.5 embryos did not show any overt abnormalities in cartilaginous or skeletal development. B. Distribution of chondrocytes on sections of rib. Paraffin-embedded sagittal sections of wt (left) and DN-Erg (right) newborn mice were stained with Alcian blue. Bars = 50 µm.</p

Morphological changes in wt and DN-Erg E18.5 chondrocytes in culture.

<p>Chondrocytes from freshly isolated from ribs of wt and DN-Erg transgenic mouse embryos (at E18.5) were cultured for up 20 days and stained with Oil red O. Phase-contrast images at days 0, 3, 9, 15 and 20 (with day 0, the day of plating) are shown (Scale bar, 50 µm).</p

Correlation of microarray data and RT-qPCR analysis.

<p>Comparison of fold change in the expression of 11 genes implicated in chondrogenesis or adipogenesis as determined by microarray analysis and RT-qPCR.</p><p>Fold change between day 0 and day 20 observed by microarray-analysis and RT-qPCR for wt and DN-Erg chondrocytes are shown. Expression levels of target genes obtained by RT-qPCR were normalised to <i>Hprt</i>. Upregulation is indicated by positive values and downregulation is indicated by negative values.</p

Cytological analysis and adipocyte quantification of femoral bone marrow of wt and DN-Erg mice.

<p>A. Sections of femorotibial joint of week 6- and week 40- wt or DN-Erg mouse. Bars = 1 mm. B. Quantification of adipocytes in bone marrow of DN-Erg and wt femoro-tibial section. The result was expressed as the mean of total adipocyte number per square millimeter of marrow tissue area in the analysed fields of at least three different mouse. C. Cytological examination of bone marrow in a femur section of 40 week-old wt and DN-Erg mice. Left, Magnification: ×2.5. Right: higher magnification view (×10).</p

Expression of chondrogenic and adipogenic markers during monolayer culture of wt and DN-Erg chondrocytes.

<p>A. Expression of chondrogenic genes <i>Col2a1</i>, <i>Sox9</i>, <i>Col10</i>, and <i>Runx2</i>. Gene expression was evaluated by RT-qPCR. B. Expression of adipogenic genes <i>Adpn</i>, and <i>Pparγ</i>. Gene expression was evaluated by RT-qPCR. The reported target gene: <i>Hprt</i> transcript ratio in chondrocytes was normalised to the target gene:<i>Hprt</i> transcript ratio (set to 1) of freshly plated wt chondrocytes (day 0). Data represent the mean of at least 2 independent chondrocyte cultures from 2 distinct mice for each genotype.</p