Spermatogenesis is a cyclic process in which diploid spermatogonia differentiate into haploid spermatozoa. This process is highly regulated, notably at the post-transcriptional level. MicroRNAs (miRNAs), single-stranded noncoding RNA molecules of about 20-25 nucleotides, are implicated in the regulation of many important biological pathways such as proliferation, apoptosis, and differentiation. We wondered whether miRNAs could play a role during spermatogenesis. The miRNA expression repertoire was tested in germ cells, and we present data showing that miR-34c was highly expressed only in these cells. Furthermore, our findings indicate that in male gonads, miR-34c expression is largely p53 independent in contrast to previous results showing a direct link in somatic cells between the miR-34 family and this tumor suppressor protein. In order to identify target genes involved in germinal lineage differentiation, we overexpressed miR-34c in HeLa cells, analyzed the transcriptome of these modified cells, and noticed a shift of the expression profile toward the germinal lineage. Recently, it has been shown that exogenous expression of Ddx4/Vasa in embryonic chicken stem cells (cESC) induces cESC reprogramming toward a germ cell fate. When we simultaneously expressed miR-34c in such cells, we could detect an up-regulation of germ cell-specific genes whereas the expression of other lineage specific markers remained unchanged. These data suggest that miR-34c could play a role by enhancing the germinal phenotype of cells already committed to this lineage.

miRNAs are master regulators of gene expression that play key roles in cancer metastasis. During bone metastasis, metastatic tumor cells must rewire their biology and express genes that are normally expressed by bone cells (a process called osteomimicry), which endow tumor cells with full competence for outgrowth in the bone marrow. Here, we establish miR-30 family members miR-30a, miR-30b, miR-30c, miR-30d, and miR-30e as suppressors of breast cancer bone metastasis that regulate multiple pathways, including osteomimicry. Low expression of miR-30 in primary tumors from patients with breast cancer were associated with poor relapse-free survival. In addition, estrogen receptor (ER)-negative/progesterone receptor (PR)-negative breast cancer cells expressed lower miR-30 levels than their ER/PR-positive counterparts. Overexpression of miR-30 in ER/PR-negative breast cancer cells resulted in the reduction of bone metastasis burden , miR-30 did not affect tumor cell proliferation, but did inhibit tumor cell invasion. Furthermore, overexpression of miR-30 restored bone homeostasis by reversing the effects of tumor cell-conditioned medium on osteoclastogenesis and osteoblastogenesis. A number of genes associated with osteoclastogenesis stimulation (), osteoblastogenesis inhibition (), tumor cell osteomimicry (), and invasiveness () were identified as targets for repression by miR-30. Among these genes, silencing or in ER-/PR-negative breast cancer cells recapitulated inhibitory effects of miR-30 on skeletal tumor burden Overall, our findings provide evidence that miR-30 family members employ multiple mechanisms to impede breast cancer bone metastasis and may represent attractive targets for therapeutic intervention. These findings suggest miR-30 family members may serve as an effective means to therapeutically attenuate metastasis in triple-negative breast cancer. .

Androgen signaling, via the androgen receptor (AR), is crucial in mediating prostate cancer (PCa) initiation and progression. Identifying new downstream effectors of the androgens/AR pathway will allow a better understanding of these mechanisms and could reveal novel biomarkers and/or therapeutic agents to improve the rate of patient survival. We compared the microRNA expression profiles in androgen-sensitive LNCaP cells stimulated or not with 1 nM R1881 by performing a high-throughput reverse transcriptase-quantitative PCR and found that miR-135a was upregulated. After androgen stimulation, we showed that AR directly activates the transcription of miR-135a2 gene by binding to an androgen response element in the promoter region. Our findings identify miR-135a as a novel effector in androgens/AR signaling. Using xenograft experiments in chick embryos and adult male mice, we showed that miR-135a overexpression decreases in vivo invasion abilities of prostate PC-3 cells. Through in vitro wound-healing migration and invasion assays, we demonstrated that this effect is mediated through downregulating ROCK1 and ROCK2 expression, two genes that we characterized as miR-135a direct target genes. In human surgical samples from prostatectomy, we observed that miR-135a expression was lower in tumoral compared with paired adjacent normal tissues, mainly in tumors classified with a high Gleason score (⩾8). Moreover, miR-135a expression is lower in invasive tumors, showing extraprostatic extension, as compared with intraprostatic localized tumors. In tumor relative to normal glands, we also showed a more frequently higher ROCK1 protein expression determined using a semi-quantitative immunohistochemistry analysis. Therefore, in tumor cells, the lower miR-135a expression could lead to a higher ROCK1 protein expression, which could explain their invasion abilities. The highlighted relationship between miR-135a expression level and the degree of disease aggressiveness suggests that miR-135a may be considered as a prognostic marker in human PCa.

Thyroid hormones are involved in the regulation of many physiological processes and regulate gene transcription by binding to their nuclear receptors TR␣ and TR␤. In the absence of triiodothyronine (T3), the unliganded receptors (aporeceptors) do bind DNA and repress the transcription of target genes. The role of thyroid hormone aporeceptors as repressors was observed in hypothyroid adult mice, but its physiological relevance in nonpathological hypothyroid conditions remained to be determined. Here we show that, in the normal mouse fetus, TR␣ aporeceptors repress heart rate as well as the expression of TR␤ and several genes encoding ion channels involved in cardiac contractile activity. Right after birth, when T3 concentration sharply increases, liganded TR␣ (holoreceptors) turn on the expression of some of these same genes concomitantly with heart rate increase. These data describe a physiological situation under which conversion of TR␣ from apo-receptors into holo-receptors, upon changes in T3 availability, plays a determinant role in a developmental process.

Our results reveal a novel function for TM4SF1 in AR signaling. The TM4SF1 mRNA expression is higher in prostate cancer tissues as compared to BPH samples. Inhibition of cell migration after targeted knockdown of TM4SF1 protein expression suggests its contribution to prostate cancer cell metastasis.

We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid hormone signaling during mouse brain development. The reporter system, utilizing a chimeric yeast Gal4 DNA-binding domain-thyroid hormone ligand-binding domain fusion protein to drive lacZ expression, revealed that thyroid hormone signaling starts in the midbrain roof several days before the onset of thyroid gland function, and that it remains highly heterogeneous in the central nervous system throughout pre-and postnatal development. We speculate that this heterogeneity might provide neural cells with positional information during development.

MicroRNA-135a (miR-135a) down-modulates parameters of cancer progression and its expression is decreased in metastatic breast cancers (as compared to non-metastatic tumors) as well as in prostate tumors relative to normal tissue. These expression and activity patterns are opposite to those of the Estrogen-Related Receptor α (ERRα), an orphan member of the nuclear receptor family. Indeed high expression of ERRα correlates with poor prognosis in breast and prostate cancers, and the receptor promotes various traits of cancer aggressiveness including cell invasion. Here we show that miR-135a down-regulates the expression of ERRα through specific sequences of its 3’UTR. As a consequence miR-135a also reduces the expression of downstream targets of ERRα. miR-135a also decreases cell invasive potential in an ERRα-dependent manner. Our results suggest that the decreased expression of miR-135a in metastatic tumors leads to elevated ERRα expression, resulting in increased cell invasion capacities.

BackgroundSeveral data favor androgen receptor implication in prostate cancer initiation through the induction of several gene activation programs. The aim of the study is to identify potential biomarkers for early diagnosis of prostate cancer (PCa) among androgen-regulated genes (ARG) and to evaluate comparative expression of these genes in normal prostate and normal prostate-related androgen-sensitive tissues that do not (or rarely) give rise to cancer.MethodsARG were selected in non-neoplastic adult human prostatic epithelial RWPE-1 cells stably expressing an exogenous human androgen receptor, using RNA-microarrays and validation by qRT-PCR. Expression of 48 preselected genes was quantified in tissue samples (seminal vesicles, prostate transitional zones and prostate cancers, benign prostatic hypertrophy obtained from surgical specimens) using TaqMan® low-density arrays. The diagnostic performances of these potential biomarkers were compared to that of genes known to be associated with PCa (i.e. PCA3 and DLX1).Results and DiscussionBy crossing expression studies in 26 matched PCa and normal prostate transitional zone samples, and 35 matched seminal vesicle and PCa samples, 14 genes were identified. Similarly, 9 genes were overexpressed in 15 benign prostatic hypertrophy samples, as compared to PCa samples. Overall, we selected 8 genes of interest to evaluate their diagnostic performances in comparison with that of PCA3 and DLX1. Among them, 3 genes: CRYAB, KCNMA1 and SDPR, were overexpressed in all 3 reference non-cancerous tissues. The areas under ROC curves of these genes reached those of PCA3 (0.91) and DLX1 (0.94).ConclusionsWe identified ARG with reduced expression in PCa and with significant diagnostic values for discriminating between cancerous and non-cancerous prostatic tissues, similar that of PCA3. Given their expression pattern, they could be considered as potentially protective against prostate cancer. Moreover, they could be complementary to known genes overexpressed in PCa and included along with them in multiplex diagnostic tools.