Current Molecular Medicine (v.16, #1)

Editorial: Look for Changes in 2016 by David Wan-Cheng Li (1-2).

Fibrodysplasia ossificans progressiva (FOP, MIM #135100) is a rare genetic disorder of heterotopic endochondral ossification, resulting in transformation of soft tissue into episodic bone formation. Currently, no effective treatment for FOP has been established. The causative heterozygous genetic mutations have been identified in either the intracellular glycine-serine-rich (GS) domain or kinase domain of ALK2 (Activin-like kinase-2, also known as Activin A receptor type I, ACVR1), a type I receptor of bone morphogenetic proteins (BMP). Cumulative studies support that these mutations abnormally activate BMP signaling in a ligandindependent manner by reducing the ALK2 interaction with the negative regulator FKBP12, whereas others argue a ligand-dependent BMP signaling activation in FOP. Nevertheless, in either the ligand-independent or ligand-dependent model, ALK2 receptor activation is essential for heterotopic ossification in FOP. Thus targeting ALK2 likely represents an effective treatment for FOP. In this article, we critically review the recent progress on therapeutic strategies, with a focus on development of small molecule ALK2 inhibitors to suppress BMP signaling for FOP treatment.

Calreticulin in the Heart: From Embryological Development to Cardiac Pathology. by D. Martinho-Dias, A. Leite-Moreira, P. Castro-Chaves (12-22).
Background: Calreticulin is a Ca2+-binding chaperone in the endoplasmic reticulum (ER) which is crucial to the correct embryological development of the heart in mice. Altered expression levels in the adult were correlated with several cardiac pathologies such as cardiac hypertrophy and dilated cardiomyopathy.
Aim: In this review, we aim to describe the role of calreticulin in the embryological development of the heart in mice and to clarify the relationship between the different cardiac pathologies and altered expression levels of calreticulin in the adult heart.
Conclusion: There is an ER crucial to embryogenesis in cardiomyocytes besides SR. Certain stimuli may induce reactivation of the transcription pattern present during embryogenesis, leading to overexpression of calreticulin in the heart, altering numerous signaling pathways and subsequently inducing pathology. Normalization of these transcriptional disorders holds promise in the treatment of multiple cardiac diseases.

Modulation of intracellular pH in human ovarian cancer. by C. Sanhueza, J. Araos, L. Naranjo, R. Villalobos, F. Westermeier, C. Salomon, A.R. Beltrán, M.A. Ramírez, J. Gutiérrez, F. Pardo, A. Leiva, L. Sobrevia (23-32).
To sustain tumor growth, the cancer cells need to adapt to low levels of oxygen (i.e., hypoxia) in the tumor tissue and to the tumor-associated acidic microenvironment. In this phenomenon, the activation of the sodium/proton exchanger 1 (NHE1) at the plasma membrane and the hypoxia-inducible factor (HIF) are critical for the control of the intracellular pH (pHi) and for hypoxia adaptation, respectively. Interestingly, both of these mechanisms end in sustaining cancer cell proliferation. However, regulatory mechanisms of pHi in human ovary tissue and in malignant ascites are unknown. Additionally, a potential role of NHE1 in the modulation of H+ efflux in human ovarian cancer cells is unknown. In this review, we discussed the characteristics of tumor microenvironment of primary human ovarian tumors and tumor ascites, in terms of pHi regulatory mechanisms and oxygen level. The findings described in the literature suggest that NHE1 may likely play a role in pHi regulation and cell proliferation in human ovarian cancer, potentially involving HIF2? activation. Since ovarian cancer is the fifth cause of prevalence of women cancer in Chile and is usually of late diagnosis, i.e., when the disease jeopardizes peritoneal cavity and other organs, resulting in reduced patient survival, new efforts are required to improve patient-life span and for a better understanding of the pathophysiology of the disease. The potential advantage of the use of amiloride and amiloride-derivatives for cancer treatment in terms of NHE1 expression and activity is also discussed as a therapeutic approach in human ovarian cancer.

Vagus nerve stimulation in treating depression: A tale of two stories. by T.-F. Yuan, A. Li, X. Sun, O. Arias-Carrión, S. Machado (33-39).
Vagus nerve stimulation (VNS) has been widely used to treat different neurological disorders, especially epilepsy. Accumulating evidence also suggests its potential application in antidepressive therapy, given that VNS has been confirmed by several clinical trials to exert long-term effects on mitigating depression and reducing the risk of relapse in depressed patients. Likewise, VNS has also proven to ameliorate the behavioral deficits in a rat model of depression. While the influences of VNS on monoamine metabolism and mood improvement are well-recognized, the underlying mechanisms mediating its antidepressive action remain poorly understood. Recent findings suggest that VNS-enhanced proliferation of hippocampal neural progenitor cells (NPCs) and synaptic transmission might serve as a monoamine-independent pathway contributive to the beneficial effects of VNS on depression. Here we briefly reviewed the recent progress in this field, based on which we propose that there might be, at least, two little-overlapped, and yet interactive pathways mediating the antidepressive action of VNS.

Fibroblast Growth Factor Receptors: From the Oncogenic Pathway to Targeted Therapy. by S. Saichaemchan, W. Ariyawutyakorn, M. Varella-Garcia (40-62).
The family of fibroblast growth factor (FGFs) and their receptors (FGFRs) regulates vital roles in many biological processes affecting cell proliferation, migration, differentiation and survival. Deregulation of the FGF/FGFR signaling pathway in cancers has been better understood and the main molecular mechanisms responsible for the activation of this pathway are gene mutations, gene fusions and gene amplification. DNA and RNA-based technologies have been used to detect these abnormalities, especially in FGFR1, FGFR2 and FGFR3 and tests have been developed for their detection, but no assay has been proved ideal for molecular diagnosis. Interestingly, the increase in the molecular biology knowledge has supported and assisted the development of therapeutic drugs targeting the most important components of this pathway. Multi- and selective tyrosine kinase inhibitors (TKIs) as well as monoclonal antibodies anti-FGFR are under investigation in preclinical and clinical trials. In this article, we reviewed those aspects with special emphasis on the pathway genomic alterations related to solid tumors, and the molecular diagnostic assays potentially able to stratify patients for the treatment with FGFR TKIs.

Jade-1: its structure, regulation and functions in the renal cancer. by Y.-C. Zhang, W.-Q. Du, R.-Y. Zhang, J.-N. Zheng, D.-S. Pei (63-69).
Jade-1 is originally identified by the yeast two-hybrid system as a protein partner of von Hippel-Lindau (pVHL) tumor suppressor, a well-known renal tumor suppressor. In cellular signaling pathways, many upstream Jade-1 regulators, such as pVHL, CK1?, PC1, and NPHP4, can control its activity by stabilization, phosphorylation, and nuclear translocation. Numerous downstream effectors, including ?-catenin, AKT, p21, and Bcl-2, are well modulated by Jade-1, which mainly regulates cell proliferation and apoptosis. Jade-1 is also deemed to be a candidate of transcriptional co-activator associated with histone acetyltransferase (HAT) activity. This review focuses on the anticancer role of Jade-1 in clear cell renal carcinoma and the inhibitory effect of Jade-1 on cystic renal diseases. This review aims to provide a basis of disease prevention or therapy.

Objective: We investigated mechanisms of colorectal cancer (CRC) chemoresistance to first-line chemotherapy (capecitabine plus oxaliplatin (XELOX)) and identified two putative chemoresistant microRNAs, miR-1914* and -1915, that are downregulated in plasma samples from patients with chemoresistant CRC.
Methods: A number of plasma samples from CRC patients were analyzed for the levels of miR-1914* and - 1915. Effects of stable and transient expression of 2 microRNAs in human chemoresistant CRC cell lines were analyzed. Tumor formation and chemoresistance in HCT116/5-Fu/OXA that did or did not express 2 microRNAs were analyzed in mice. Nuclear factor I/X (NFIX) was predicted to target the gene of 2 miRNAs and verified in vivo and in vitro.
Results: Plasma levels of miR-1914* and -1915 in chemoresistant CRC patients were different than levels in responders, and associated with clinical response. Overexpression of miR-1914* and -1915 in chemoresistant CRC cells reduced resistance to 5-FU and Oxaliplatin in vitro. The microRNAs suppressed chemoresistance in CRC tumors in mice by affecting cell growth, invasion, apoptosis and tumor suppressor function. miR-1914* and -1915 interacted with the 3'-untranslated region of NFIX and reduced NFIX its level in chemoresistant CRC cells. Overexpression of NFIX did not inhibit chemoresistant CRC cell motility and chemoresistant proteins when miR-1914* and -1915 were transfected.
Conclusion: Plasma miR-1914* and -1915 interact with NFIX RNA and reduce its level in chemoresistant CRC cells to first-line chemotherapy. Up-regulation of miR-1914* and -1915 decreased the chemoresistance abilities of chemoresistant CRC cells. The plasma miR-1914* and -1915 may play a role in colorectal cancer therapy and diagnosis.

Metformin Restrains Pancreatic Duodenal Homeobox-1 (PDX-1) Function by Inhibiting ERK Signaling in Pancreatic Ductal Adenocarcinoma. by G. Zhou, J. Yu, A. Wang, S.-H. Liu, J. Sinnett-Smith, J. Wu, R. Sanchez, J. Nemunaitis, C. Ricordi, E. Rozengurt, F.C. Brunicardi (83-90).
Pancreatic ductal adenocarcinoma (PDAC) is one of the most potent and perilous diseases known, with a median survival rate of 3-5 months due to the combination of only advanced stage diagnosis and ineffective therapeutic options. Metformin (1,1-Dimethylbiguanide hydrochloride), the leading drug used for type 2 diabetes mellitus, emerges as a potential therapy for PDAC and other human cancers. Metformin exerts its anticancer action via a variety of adenosine monophosphate (AMP)-activated protein kinase (AMPK)- dependent and/or AMPK-independent mechanisms. We present data here showing that metformin downregulated pancreatic transcription factor pancreatic duodenal homeobox-1 (PDX-1), suggesting a potential novel mechanism by which metformin exerts its anticancer action. Metformin inhibited PDX-1 expression at both protein and mRNA levels and PDX-1 transactivity as well in PDAC cells. Extracellular signal-regulated kinase (ERK) was identified as a PDX-1-interacting protein by antibody array screening in GFP-PDX-1 stable HEK293 cells. Co-transfection of ERK1 with PDX-1 resulted in an enhanced PDX-1 expression in HEK293 cells in a dose-dependent manner. Immunoprecipitation/Western blotting analysis confirmed the ERK-PDX-1 interaction in PANC-1 cells stimulated by epidermal growth factor (EGF). EGF induced an enhanced PDX-1 expression in PANC-1 cells and this stimulation was inhibited by MEK inhibitor PD0325901. Metformin inhibited EGF-stimulated PDX-1 expression with an accompanied inhibition of ERK kinase activation in PANC- 1 cells. Taken together, our studies show that PDX-1 is a potential novel target for metformin in PDAC cells and that metformin may exert its anticancer action in PDAC by down-regulating PDX-1 via a mechanism involving inhibition of ERK signaling.

DREADD in parvalbumin interneurons of the dentate gyrus modulates anxiety, social interaction and memory extinction. by D. Zou, L. Chen, D. Deng, D. Jiang, F. Dong, C. McSweeney, Y. Zhou, L. Liu, G. Chen, Y. Wu, Y. Mao (91-102).
Parvalbumin (PV)-positive interneurons in the hippocampus play a critical role in animal memory, such as spatial working memory. However, how PV-positive interneurons in the subregions of the hippocampus affect animal behaviors remains poorly defined. Here, we achieved specific and reversible activation of PV-positive interneurons using designer receptors exclusively activated by designer drugs (DREADD) technology. Inducible DREADD expression was demonstrated in vitro in cultured neurons, in which co-transfection of the hM3D-Gq-mCherry vector with a Cre plasmid resulted in a cellular response to hM3Dq ligand clozapine-N-oxide (CNO) stimulation. In addition, the dentate gyrus (DG) of PV-Cre mice received bilateral injection of control lentivirus or lentivirus expressing double floxed hM3D-Gq-mCherry. Selective activation of PV-positive interneurons in the DG did not affect locomotor activity or depression-related behavior in mice. Interestingly, stimulation of PV-positive interneurons induced an anxiolytic effect. Activation of PVpositive interneurons appears to impair social interaction to novelty, but has no effect on social motivation. However, this defect is likely due to the anxiolytic effect as the exploratory behavior of mice expressing hM3DGq is significantly increased. Mice expressing hM3D-Gq did not affect novel object recognition. Activation of PV-positive interneurons in the DG maintains intact cued and contextual fear memory but facilitates fear extinction. Collectively, our results demonstrated that proper control of PV interneurons activity in the DG is critical for regulation of the anxiety, social interaction and fear extinction. These results improve our fundamental understanding of the physiological role of PV-positive interneurons in the hippocampus.