Identification of Ran-binding protein M as a stanniocalcin 2 interacting protein and implications for androgen receptor activity

Decidualized endometrial stromal cells present with altered androgen response in PCOS

Hyperandrogenic women with PCOS show disrupted decidualization (DE) and placentation. Dihydrotestosterone (DHT) is reported to enhance DE in non-PCOS endometrial stromal cells (eSC_Ctrl); however, this has not been assessed in PCOS cells (eSC_PCOS). Therefore, we studied the transcriptome profile of non-decidualized (non-DE) and DE eSCs from women with PCOS and Ctrl in response to short-term estradiol (E2) and/or progesterone (P4) exposure with/without (±) DHT. The non-DE eSCs were subjected to E2 ± DHT treatment, whereas the DE (0.5 mM 8-Br-cAMP, 96 h) eSCs were post-treated with E2 and P4 ± DHT, and RNA-sequenced. Validation was performed by immunofluorescence and immunohistochemistry. The results showed that, regardless of treatment, the PCOS and Ctrl samples clustered separately. The comparison of DE vs. non-DE eSC_PCOS without DHT revealed PCOS-specific differentially expressed genes (DEGs) involved in mitochondrial function and progesterone signaling. When further adding DHT, we detected altered responses for lysophosphatidic acid (LPA), inflammation, and androgen signaling. Overall, the results highlight an underlying defect in decidualized eSC_PCOS, present with or without DHT exposure, and possibly linked to the altered pregnancy outcomes. We also report novel factors which elucidate the mechanisms of endometrial dysfunction in PCOS.

Antioncogenic Effect of MicroRNA-206 on Neck Squamous Cell Carcinoma Through Inhibition of Proliferation and Promotion of Apoptosis and Autophagy

Recent studies have reported the crucial role of stanniocalcin-2 (STC2) in hepatocellular carcinoma; however, its role in head and neck squamous cell carcinoma (HNSCC) remains elusive. In this study, microRNA-206 (miR-206) was predicted to target STC2 gene. The study herein aimed to elucidate the effect of miR-206 on HNSCC by targeting STC2. STC2 was highly expressed in HNSCC tissues and cells. By targeting STC2, miR-206 decreased mRNA and protein expression of STC2. Importantly, our study showed that miR-206 blocked the Akt signaling pathway by inhibiting STC2. Intriguingly, our data from in vitro and in vivo experiments suggested that miR-206 overexpression led to decreased cell proliferation and increased cell apoptosis and autophagy, as well as suppressed tumor growth; whereas, STC2 silencing reversed the effects of miR-206 inhibitor on those biological behaviors. In this study, we investigated the antioncogenic effect of miR-206 on HNSCC by targeting STC2, and highlighted miR-206/STC2 aixs as potential therapeutic targets for HNSCC.

New Insights Into Physiological and Pathophysiological Functions of Stanniocalcin 2

Stanniocalcin, a glycosylated peptide hormone, first discovered in a bony fish has originally been shown to play critical role in calcium and phosphate homeostasis. Two paralogs of stanniocalcin (STC1 and STC2) identified in mammals are widely expressed in variety of tissues. This review provides historical perspective on the discovery of fish and mammalian stanniocalcin, describes molecular regulation of STC2 gene, catalogs distribution as well as expression of STC2 in tissues, and provides key structural information known till date regarding mammalian STC2. Additionally, this mini review summarizes pivotal functions of STC2 in calcium and phosphate regulation, cytoprotection, cell development, and angiogenesis. Finally, STC2's role as a novel marker for human cancers has also been outlined. Reviewing these studies will provide an opportunity to understand STC2's structure, biological functions as well as key molecular pathways involving STC2, which will help us design innovative therapeutic interventions using this novel hormone.

Molecular characterization, expression analysis, and functional properties of multiple 5-hydroxytryptamine receptors in Pacific abalone (Haliotis discus hannai)

Neurotransmitters such as serotonin (5-hydroxytryptamine; 5-HT) in the central nervous system regulate diverse physiological functions, including reproduction, feeding, learning, and memory, in diverse animal phyla. 5-HT and the 5-HT1 subtype receptor play important roles in sexual maturation and in the initiation of gamete release in mollusks. However, little is known about the involvement of other 5-HT receptor subfamilies in the reproduction process. In the present study, we identified the cDNAs encoding eight subtypes of 5-HT receptors from the ganglia tissues of the Pacific abalone Haliotis discus hannai (Mollusca; Gastropoda; Haliotidae), and examined the gonadal expression of the transcripts of 5-HT receptors. A phylogenetic analysis indicated that the molluskan 5-HT receptors are largely classified into four major clades: 5-HT1/5/7, 5-HT2, 5-HT4, and 5-HT6. Among the H. discus hannai (Hdh) 5-HT1-7 transcripts, Hdh5-HT1B, 4A, 4B, and 6 were the major subtypes detected in the mature ovary. Estradiol-17β injection into the pedal sinus induced the downregulation of 5-HT4B and upregulation of 5-HT6 transcripts in the ovary of mature abalone within 72 h. In HEK293 cells overexpressing Hdh5-HT1B, forskolin-stimulated cAMP response element luciferase (CRE-Luc) reporter activity was inhibited by 5-HT in a dose-dependent manner, whereas serum response element luciferase (SRE-Luc) activity was not affected. In Hdh5-HT4A-expressing HEK293 cells, forskolin-stimulated CRE-Luc and SRE-Luc reporter activities were both marginally increased by treatment with a high dose of 5-HT. Our results provide new insights into the roles of 5-HT through diverse G protein-coupled 5-HT receptors in the reproductive process of mollusks.

Cell signalling pathway regulation by RanBPM: molecular insights and disease implications

RanBPM (Ran-binding protein M, also called RanBP9) is an evolutionarily conserved, ubiquitous protein which localizes to both nucleus and cytoplasm. RanBPM has been implicated in the regulation of a number of signalling pathways to regulate several cellular processes such as apoptosis, cell adhesion, migration as well as transcription, and plays a critical role during development. In addition, RanBPM has been shown to regulate pathways implicated in cancer and Alzheimer's disease, implying that RanBPM has important functions in both normal and pathological development. While its functions in these processes are still poorly understood, RanBPM has been identified as a component of a large complex, termed the CTLH (C-terminal to LisH) complex. The yeast homologue of this complex functions as an E3 ubiquitin ligase that targets enzymes of the gluconeogenesis pathway. While the CTLH complex E3 ubiquitin ligase activity and substrates still remain to be characterized, the high level of conservation between the complexes in yeast and mammals infers that the CTLH complex could also serve to promote the degradation of specific substrates through ubiquitination, therefore suggesting the possibility that RanBPM's various functions may be mediated through the activity of the CTLH complex.

Tumor suppressor functions of DAXX through histone H3.3/H3K9me3 pathway in pancreatic NETs

Pancreatic neuroendocrine tumors (PanNETs) have considerable malignant potential. Frequent somatic mutations and loss of DAXX protein expression have been found in PanNETs. DAXX is known as a transcriptional repressor; however, molecular functions underlying DAXX loss remain unclear in PanNETs. We evaluated DAXX expression by immunohistochemistry in 44 PanNETs. DAXX-knockdown (KD) and -knockout (KO) PanNET cells were analyzed for in vitro and vivo The target genes were screened by microarray and chromatin immunoprecipitation (ChIP) assays for DAXX, histone H3.3 and H3K9me3 complex. In clinicopathological features, low DAXX expression was significantly correlated with nonfunctional tumors, higher Ki-67 index and WHO grade. Microarray and ChIP assays of DAXX-KD/KO identified 12 genes as the direct targets of DAXX transcriptional repressor. Among them, expression of five genes including STC2 was suppressed by DAXX/H3.3/H3K9me3 pathway. DAXX-KD/KO cells enhanced sphere forming activity, but its effect was suppressed by knockdown of STC2 In xenograft models, tumorigenicity and tumor vessel density were significantly increased in DAXX-KO cells with high expression of STC2. Clinically, higher recurrence rate was recognized in PanNETs with low expression of DAXX and high expression of STC2 than others (P = 0.018). Our data suggest that DAXX plays as a tumor suppressor and DAXX/H3.3 complex suppresses target genes by promoting H3K9me3 in PanNETs. Combination of DAXX loss and its target gene STC2 overexpression might be effective biomarkers and therapeutic candidates.

Stanniocalcin 2 induces oxaliplatin resistance in colorectal cancer cells by upregulating P-glycoprotein

Multidrug resistance (MDR) limits the anticancer effects of chemotherapy in patients with metastatic colorectal cancer (CRC). Oxaliplatin is a common component of combinational therapeutic regimens administered to patients with metastatic CRC; however, it is also used as a constituent of adjuvant therapy for patients at a risk of recurrent disease. In the present study, we investigated the role of stanniocalcin 2 (STC2) in chemoresistance. STC2 knockdown sensitized chemoresistant CRC cells to oxaliplatin. Moreover, the expression of exogenous STC2 in chemonaïve CRC cells induced oxaliplatin resistance. We confirmed that STC2 upregulated P-glycoprotein (P-gp) expression in CRC cells. Furthermore, shRNA against phosphoinositide 3-kinase (PI3K) or Akt inhibited the action of STC2 on P-gp upregulation and MDR in CRC. To our knowledge, this is the first report to demonstrate the induction of oxaliplatin resistance in CRC cells in response to STC2 stimulation of P-gp via the PI3K/Akt signaling pathway.