Identification of a new tumor suppressor gene located at chromosome 8p21.3-22

FTO-mediated demethylation of MTUS1/ATIP1 promotes tumor progression in head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) has been recognized as the seventh most prevalent malignant tumor globally. It is a malignant neoplasm that arises from the mucosal epithelium of head and neck region. In our previous research, we have demonstrated that MTUS1/ATIP1 exhibits anti-cancer properties in HNSCC. Nevertheless, the underlying mechanism responsible for the reduction of MTUS1/ATIP1 expression has not been investigated.

METHODS

HNSCC and adjacent normal tissues were collected and examined using m6A MeRIP-seq, qRT-PCR, and IHC to investigate the relationship between MTUS1/ATIP1 and FTO. MeRIP-qPCR, m6A dot blot, RNA and protein stability assays, and RNC-qRT-PCR were employed to elucidate the mechanism by which FTO mediates demethylation of MTUS1/ATIP1 in HNSCC. Functional assays, subcutaneous tumorigenesis, and in situ tongue cancer models were conducted to assess the impact of the FTO-MTUS1/ATIP1 pathway on proliferative capacity of HNSCC tumors.

RESULTS

FTO was observed to be markedly upregulated and showed a negative correlation with MTUS1/ATIP1 expression in HNSCC. FTO was responsible for mediating m6A demethylation in the 3'UTR of MTUS1/ATIP1, leading to its degradation. Additionally, silencing MTUS1/ATIP1 successfully reversed the tumor-promoting effects on HNSCC triggered by FTO in in vitro and in vivo.

CONCLUSIONS

Our research elucidated the functional importance of FTO-mediated m6A demethylation of MTUS1/ATIP1, suggesting that targeting the FTO-MTUS1/ATIP1 axis could be a prospective novel approach for treating HNSCC.

Agonists of galanin subtype 2 receptor may prevent pancreatic cancer and agonists of angiotensin II type 2 receptor may prevent colorectal cancer

Pancreatic ductal adenocarcinoma (PDAC) remains a dreadful disease with poor prognosis. While the prognosis of colorectal carcinoma (CRC) is better than that of PDAC, it still is the second-leading cause of cancer deaths worldwide. Recently, a (methyl)lanthionine-stabilized, highly receptor-specific agonist of galanin subtype 2 (GAL2) receptor inhibited the growth of GAL2 receptor-expressing patient-derived xenografts (PDX) of pancreatic cancer. Furthermore, a lanthionine-constrained agonist of angiotensin II type 2 (AT2) receptor inhibited PDX of colorectal cancer in mice. Stimulation of GAL2 receptor may modulate immune surveillance and inhibits PDAC via cell cycle inhibition and apoptosis. Consistent with GAL2 receptor-mediated tumor inhibition, for PDAC, survival is much higher for patients with high GAL2 receptor expression. Importantly, a (methyl)lanthionine-stabilized GAL2 receptor-specific agonist enhances expression of GAL2 receptor, not only in PDAC-PDX but also in healthy tissue indicating therapeutic and preventive potentials for GAL2 receptor agonists. AT2 receptor is interacting with four tumor suppressor proteins, Src homology phosphatase 1, Src homology phosphatase 2, Promyelocytic Leukemia Zinc Finger protein and Microtuble-Associated Scaffold Protein1, the latter also known as Angiotensin-II type 2 receptor-Interacting Protein. Pathways linked to these tumor suppressor proteins may enhance immune surveillance, prevent carcinogenesis, counter proliferation and stimulate apoptosis. Taken together, current data are prompting the hypothesis of a prophylactic treatment option with stable, specific and safe agonists of GAL2 receptor and AT2 receptor to prevent the emergence of pancreatic and colorectal cancer in individuals at risk.

Four centrosome-related genes to predict the prognosis and drug sensitivity of patients with colon cancer

BACKGROUND

As the primary microtubule organizing center in animal cells, centrosome abnormalities are involved in human colon cancer.

AIM

To explore the role of centrosome-related genes (CRGs) in colon cancer.

METHODS

CRGs were collected from public databases. Consensus clustering analysis was performed to separate the Cancer Genome Atlas cohort. Univariate Cox and least absolute shrinkage selection operator regression analyses were performed to identify candidate prognostic CRGs and construct a centrosome-related signature (CRS) to score colon cancer patients. A nomogram was developed to evaluate the CRS risk in colon cancer patients. An integrated bioinformatics analysis was conducted to explore the correlation between the CRS and tumor immune microenvironment and response to immunotherapy, chemotherapy, and targeted therapy. Single-cell transcriptome analysis was conducted to examine the immune cell landscape of core prognostic genes.

RESULTS

A total of 726 CRGs were collected from public databases. A CRS was constructed, which consisted of the following four genes: TSC1, AXIN2, COPS7A, and MTUS1. Colon cancer patients with a high-risk signature had poor survival. Patients with a high-risk signature exhibited decreased levels of plasma cells and activated memory CD4+ T cells. Regarding treatment response, patients with a high-risk signature were resistant to immunotherapy, chemotherapy, and targeted therapy. COPS7A expression was relatively high in endothelial cells and fibroblasts. MTUS1 expression was high in endothelial cells, fibroblasts, and malignant cells.

CONCLUSION

We constructed a centrosome-related prognostic signature that can accurately predict the prognosis of colon cancer patients, contributing to the development of individualized treatment for colon cancer.

The Angiotensin AT2 Receptor: From a Binding Site to a Novel Therapeutic Target

Discovered more than 30 years ago, the angiotensin AT2 receptor (AT2R) has evolved from a binding site with unknown function to a firmly established major effector within the protective arm of the renin-angiotensin system (RAS) and a target for new drugs in development. The AT2R represents an endogenous protective mechanism that can be manipulated in the majority of preclinical models to alleviate lung, renal, cardiovascular, metabolic, cutaneous, and neural diseases as well as cancer. This article is a comprehensive review summarizing our current knowledge of the AT2R, from its discovery to its position within the RAS and its overall functions. This is followed by an in-depth look at the characteristics of the AT2R, including its structure, intracellular signaling, homo- and heterodimerization, and expression. AT2R-selective ligands, from endogenous peptides to synthetic peptides and nonpeptide molecules that are used as research tools, are discussed. Finally, we summarize the known physiological roles of the AT2R and its abundant protective effects in multiple experimental disease models and expound on AT2R ligands that are undergoing development for clinical use. The present review highlights the controversial aspects and gaps in our knowledge of this receptor and illuminates future perspectives for AT2R research. SIGNIFICANCE STATEMENT: The angiotensin AT2 receptor (AT2R) is now regarded as a fully functional and important component of the renin-angiotensin system, with the potential of exerting protective actions in a variety of diseases. This review provides an in-depth view of the AT2R, which has progressed from being an enigma to becoming a therapeutic target.

SCARA3 inhibits cell proliferation and EMT through AKT signaling pathway in lung cancer

BACKGROUND

Scavenger receptor class A member 3 (SCARA3) is decreased in prostate cancer and myeloma. However, functions of SCARA3 in various cancers remain unclear. In this study, we tried to evaluate the functional study of SCARA3 in lung cancer.

METHODS

The expression level of SCARA3 in the TCGA-database, lung cancer tissue microarray and lung cancer cells and the prognosis of lung cancer patients were measured. Lung cancer tissue microarray was analyzed pathologically using immunohistochemistry, and quantitative analysis of SCARA3 in normal lung cells and lung cancer cells was analyzed using western blot analysis. Survival curves for lung cancer patients were prepared with the Kaplan-Meier method. Migration and invasion of SCARA3 overexpressed lung cancer cells were determined using a Transwell chamber system. Proliferation of lung cancer cells was determined based on cell viability assay using cell culture in vitro and a tumorigenicity model of BALB/C nude mouse in vivo.

RESULTS

The expression of SCARA3 was abnormally reduced in TCGA-database, lung tissue microarray, and various lung cancer cells. However, overexpression of SCARA3 reduced the proliferation of lung cancer. The ability of SCARA3 to inhibit cancer cell proliferation was maintained even in vivo using a mouse xenograft model. In addition, overexpression of SCARA3 reduced migration and invasion ability of lung cancer cells and induced decreases of EMT markers such as β-catenin, vimentin, and MMP9. We aimed to prove the role of SCARA3 in the treatment of Lung cancer, and shown that the expression level of SCARA3 is important in cancer treatment using cisplatin. The enhancement of the effect of cisplatin according to SCARA3 overexpression is via the AKT and JNK pathways.

CONCLUSIONS

This study confirmed an abnormal decrease in SCARA3 in lung cancer. Overexpression of SCARA3 potently inhibited tumors in lung cancer and induced apoptosis by increasing sensitivity of lung cancer to cisplatin. These results suggest that SCARA3 is a major biomarker of lung cancer and that the induction of SCARA3 overexpression can indicate an effective treatment.

An Insight into GPCR and G-Proteins as Cancer Drivers

G-protein-coupled receptors (GPCRs) are the largest family of cell surface signaling receptors known to play a crucial role in various physiological functions, including tumor growth and metastasis. Various molecules such as hormones, lipids, peptides, and neurotransmitters activate GPCRs that enable the coupling of these receptors to highly specialized transducer proteins, called G-proteins, and initiate multiple signaling pathways. Integration of these intricate networks of signaling cascades leads to numerous biochemical responses involved in diverse pathophysiological activities, including cancer development. While several studies indicate the role of GPCRs in controlling various aspects of cancer progression such as tumor growth, invasion, migration, survival, and metastasis through its aberrant overexpression, mutations, or increased release of agonists, the explicit mechanisms of the involvement of GPCRs in cancer progression is still puzzling. This review provides an insight into the various responses mediated by GPCRs in the development of cancers, the molecular mechanisms involved and the novel pharmacological approaches currently preferred for the treatment of cancer. Thus, these findings extend the knowledge of GPCRs in cancer cells and help in the identification of therapeutics for cancer patients.

Mitochondrial Tumor Suppressors-The Energetic Enemies of Tumor Progression

Tumor suppressors represent a critical line of defense against tumorigenesis. Their mechanisms of action and the pathways they are involved in provide important insights into cancer progression, vulnerabilities, and treatment options. Although nuclear and cytosolic tumor suppressors have been extensively investigated, relatively little is known about tumor suppressors localized within the mitochondria. However, recent research has begun to uncover the roles of these important proteins in suppressing tumorigenesis. Here, we review this newly developing field and summarize available information on mitochondrial tumor suppressors.

Ribosome-Induced Cellular Multipotency, an Emerging Avenue in Cell Fate Reversal

The ribosome, which is present in all three domains of life, plays a well-established, critical role in the translation process by decoding messenger RNA into protein. Ribosomal proteins, in contrast, appear to play non-translational roles in growth, differentiation, and disease. We recently discovered that ribosomes are involved in reverting cellular potency to a multipotent state. Ribosomal incorporation (the uptake of free ribosome by living cells) can direct the fate of both somatic and cancer cells into multipotency, allowing them to switch cell lineage. During this process, both types of cells experienced cell-cycle arrest and cellular stress while remaining multipotent. This review provides a molecular perspective on current insights into ribosome-induced multipotency and sheds light on how a common stress-associated mechanism may be involved. We also discuss the impact of this phenomenon on cancer cell reprogramming and its potential in cancer therapy.

Low-Level Expression of MTUS1 Is Associated with Poor Survival in Patients with Lung Adenocarcinoma

Microtubule-associated tumor suppressor 1 (MTUS1) is thought to be downregulated in arious human cancers, which suggests its role as a tumor suppressor. This study investigated the clinicopathological significance of MTUS1 expression in lung adenocarcinoma. Tissue microarray blocks consisting of 161 cases were constructed, and immunohistochemical staining was used to assess MTUS1 expression. Correlations of MTUS1 expression and clinicopathological parameters were analyzed. In addition, we used public databases and performed bioinformatics analysis. Low level of MTUS1 was significantly associated with higher clinical stage (p = 0.006), higher tumor stage (p = 0.044), lymph node metastasis (p = 0.01), worse histologic grade (p = 0.007), lymphovascular invasion (p = 0.014), and higher Ki-67 proliferation index (p < 0.001). Patients with low MTUS1 expression also showed shorter disease-free survival (p = 0.002) and cancer-specific survival (p = 0.006). Analysis of data from the Cancer Genome Atlas confirmed that the mRNA expression of MTUS1 in lung adenocarcinoma was significantly lower than that of normal lung tissue (p = 0.02), and patients with decreased MTUS1 expression showed significantly shorter overall survival (p = 0.008). These results suggest that MTUS1 may be a potential biomarker for predicting clinical outcomes in lung adenocarcinoma patients.

In silico analysis of deleterious SNPs of human MTUS1 gene and their impacts on subsequent protein structure and function

The mitochondrial tumor suppressor 1 (MTUS1) gene acts as a crucial tumor suppressor by inhibiting growth and proliferation of eukaryotic cells including tumor cell lines. Down regulation of MTUS1 gene has been implicated in a wide range of cancers as well as various human diseases. Alteration through nsSNPs can potentially damage the structure and/or function of the protein. As characterization of functional SNPs in such disease linked genes is a major challenge, it is feasible to analyze putative functional SNPs prior to performing larger population studies. Hence, in this in silico study we differentiated the potentially harmful nsSNPs of the MTUS1 gene from the neutral ones by using various sequence and structure based bioinformatic tools. In a total of 215 nsSNPs, 9 were found to be most likely to exert deleterious effect using 7 prediction tools. From which, 5nsSNPs (S1259L, E960K, P503T, L1084V and L1143Q) were selected as potentially damaging due to their presence in the highly conserved region and ability to decrease protein stability. In fact, 2 nsSNPs (S1259L and E960K) among these 5 were found to be individually associated with two distinctive cancers named Stomach adenocarcinoma and Uterine corpus endometrial carcinoma. As this is the first comprehensive study analyzing the functional nsSNPs of MTUS1, the results of the current study would certainly be helpful in future prospects concerning large population-based studies as well as drug discovery, especially developing individualized medicine.

Microtubule-Associated Protein ATIP3, an Emerging Target for Personalized Medicine in Breast Cancer

Breast cancer is the leading cause of death by malignancy among women worldwide. Clinical data and molecular characteristics of breast tumors are essential to guide clinician’s therapeutic decisions. In the new era of precision medicine, that aims at personalizing the treatment for each patient, there is urgent need to identify robust companion biomarkers for new targeted therapies. This review focuses on ATIP3, a potent anti-cancer protein encoded by candidate tumor suppressor gene MTUS1, whose expression levels are markedly down-regulated in breast cancer. ATIP3 is a microtubule-associated protein identified both as a prognostic biomarker of patient survival and a predictive biomarker of breast tumors response to taxane-based chemotherapy. We present here recent studies pointing out ATIP3 as an emerging anti-cancer protein and a potential companion biomarker to be combined with future personalized therapy against ATIP3-deficient breast cancer.

The Tumor Suppressor MTUS1/ATIP1 Modulates Tumor Promotion in Glioma: Association with Epigenetics and DNA Repair

Simple Summary

Despite multidisciplinary treatments, survival remains poor in glioma patients. Although novel therapeutic approaches are being explored, no outstanding effects on the survival have been achieved so far, which substantiates the need to develop new therapeutic strategies. To understand the mechanisms responsible for its high malignancy and obligatory recurrence, we examined the impact of MTUS1, a tumor-suppressor gene (TSG), coding for ATIP1, in glioma malignancy as well as how its expression might influence glioma therapy. We confirmed that in glioma cells, elevated ATIP1 expression damps tumor progression by mitigating proliferation and motility. Additionally, MTUS1/ATIP1 can be used as a biological marker to predict therapy outcomes. In glioma cell lines, glioma sphere cultures (GSC), high-grade glioma (HGG) and especially in glioma recurrence, MTUS1/ATIP1 expression is downregulated, probably by promoter hypermethylation. However, in GBM, high ATIP1 expression might interfere with radiation-therapy since elevated expression of MTUS1/ATIP1 drives double-strand break (DSB) DNA repair.

Abstract

Glioblastoma (GBM) is a highly aggressive brain tumor. Resistance mechanisms in GBM present an array of challenges to understand its biology and to develop novel therapeutic strategies. We investigated the role of a TSG, MTUS1/ATIP1 in glioma. Glioma specimen, cells and low passage GBM sphere cultures (GSC) were analyzed for MTUS1/ATIP1 expression at the RNA and protein level. Methylation analyses were done by bisulfite sequencing (BSS). The consequence of chemotherapy and irradiation on ATIP1 expression and the influence of different cellular ATIP1 levels on survival was examined in vitro and in vivo. MTUS1/ATIP1 was downregulated in high-grade glioma (HGG), GSC and GBM cells and hypermethylation at the ATIP1 promoter region seems to be at least partially responsible for this downregulation. ATIP1 overexpression significantly reduced glioma progression by mitigating cell motility, proliferation and facilitate cell death. In glioma-bearing mice, elevated MTUS1/ATIP1 expression prolonged their survival. Chemotherapy, as well as irradiation, recovered ATIP1 expression both in vitro and in vivo. Surprisingly, ATIP1 overexpression increased irradiation-induced DNA-damage repair, resulting in radio-resistance. Our findings indicate that MTUS1/ATIP1 serves as TSG-regulating gliomagenesis, progression and therapy resistance. In HGG, higher MTUS1/ATIP1 expression might interfere with tumor irradiation therapy.

lncRNA LIFR‑AS1 inhibits gastric carcinoma cell proliferation, migration and invasion by sponging miR‑4698

The vital functions of long non-coding (lnc)RNAs have been verified in gastric carcinoma (GC). However, as a novel cancer-related lncRNA, the influence of leukemia inhibitory factor receptor antisense RNA 1 (LIFR-AS1) in GC cell biological behaviors remains unreported. The present study explored the biological effects of lncRNA LIFR-AS1 on GC progression. Reverse transcription-quantitative PCR was performed to examine lncRNA LIFR-AS1 expression in GC tissues and cells. Cell Counting Kit-8, 5-ethynyl-2′-deoxyuridine incorporation, cell wound healing and Transwell invasion assays were used to assess the functions of lncRNA LIFR-AS1 in GC cell proliferation, migration and invasion. Additionally, associations among lncRNA LIFR-AS1, microRNA (miR)-4698 and microtubule-associated tumor suppressor 1 (MTUS1) were investigated via bioinformatics software and a luciferase reporter system. In addition, western blotting was used to examine the expression of MEK and ERK. Decreased lncRNA LIFR-AS1 expression was observed in GC tissues and cells. Upregulated lncRNA LIFR-AS1 inhibited GC cell proliferation, migration and invasion. Upregulated miR-4698 and downregulated MTUS1 were identified in GC tissues and cells. The inhibitory interaction between lncRNA LIFR-AS1 and miR-4698 was confirmed. Additionally, MTUS1 was predicted as a target gene of miR-4698 positively regulated by lncRNA LIFR-AS1. The MEK/ERK pathway was inhibited by lncRNA LIFR-AS1 via regulating MTUS1. These findings revealed the inhibitory functions of lncRNA LIFR-AS1 in GC cell proliferation, migration and invasion. The process was mediated via miR-4698, MTUS1 and the MEK/ERK pathway.

AT2 receptor interacting protein 1 (ATIP1) mediates COX-2 induction by an AT2 receptor agonist in endothelial cells

Angiotensin II (Ang II) type 2 receptor (AT2R) is one of the major components of the renin-angiotensin-aldosterone system. Nevertheless, the physiological role is not well defined compared to the understanding of the Ang II type 1 receptor (AT1R), which is a well characterized G-protein coupled receptor in the cardiovascular system. While the AT2R signaling pathway remains unclear, AT2 receptor interacting protein 1 (ATIP1) has been identified as a candidate molecule for interacting with the C-terminal region of AT2R. In this study, we investigated the ATIP1 dependent AT2R inducible genes in human umbilical vein endothelial cells (HUVECs). CGP42112A, an AT2R specific agonist, resulted in an upregulation of inflammatory genes in HUVECs, which were inhibited by knocking down ATIP1 with siRNA (siATIP1). Among them, we confirmed by quantitative PCR that the induction of COX-2 mRNA expression was significantly downregulated by siATIP1. COX-2 was also upregulated by Ang II stimulation. This upregulation was suppressed by treatment with the AT2R specific antagonist PD123319, which was not replicated by the AT1R antagonist telmisartan.

These findings suggest that ATIP1 plays an important role in AT2R dependent inflammatory responses. This may provide a new approach to the development of cardio-protective drugs.

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Only the AT2 receptor interacting protein 1 (ATIP1) of ATIP isoforms expresses in endothelial cells.

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A novel anti-ATIP monoclonal antibody detected endogenous ATIP1 and revealed ATIP1 localization in endothelial cells.

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AT2 receptor (AT2R) agonist stimulation induced inflammatory gene expression via ATIP1 in endothelial cells.

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An AT2R specific inhibitor blocks the Ang II induction of COX-2 mRNA in endothelial cells.

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There is the AT2R-ATIP1 related pathway of COX-2 induction in endothelial cells.

Loss of MTUS1 Expression Is Associated With Poor Prognosis in Patients With Gallbladder Carcinoma

BACKGROUND/AIM

Microtubule-associated scaffold protein 1 (MTUS1) acts as tumor suppressor in several cancer types. This study assessed the relationship between clinicopathological characteristics and expression of microRNA candidates based on MTUS1 expression in gallbladder cancer (GBC).

MATERIALS AND METHODS

MTUS1 expression was evaluated by immunohistochemical staining of tissue microarrays from 109 cases of GBC. The association of MTUS1 expression with clinicopathological factors was explored. Two microRNA candidates (miR-19a-3p, and miR-19b-3p), which were identified by a literature review and computational analysis, were assessed in GBC tissue samples by quantitative real-time polymerase chain reaction.

RESULTS

Low MTUS1 expression in GBC was associated with high histological grade, perineural invasion, lymphovascular invasion, high T-stage, advanced TNM stage, poorer disease-free survival, and poorer cancer-specific survival. No statistical association between MTUS1 expression and expression of microRNA candidates was observed.

CONCLUSION

MTUS1 may act as tumor suppressor and might be a potential biomarker for predicting prognosis in GBC.

A de novo Mutation in the MTUS1 Gene Decreases the Risk of Non-compaction of Ventricular Myocardium via the Rac1/Cdc42 Pathway

Background: The MTUS1 gene encodes a microtubule-associated protein involved in multiple processes including cell polarity and microtubule balance during myocardial development. Aims: To investigate the association between a de novo c. 2617A->C mutation in MTUS1 (NM_001001924.2) and non-compaction of ventricular myocardium (NVM) and explore the potential mechanisms. Methods: A de novo mutation in MTUS1 was identified for a familial pedigree with NVM. Lentiviral vectors containing MTUS1 wild type or the mutation MTUS1 were constructed and co-infected into HEK-293 cells. MTUS1, Rac1/Cdc42, α-tubulin, α/β-tubulin, polarity protein (PAR6), and the morphology of daughter cells were measured by real-time PCR, Western blot, and immunofluorescence assays, respectively. Results: The lentiviral vectors were constructed successfully. Immunofluorescence assays revealed the fluorescence intensity of α-tubulin to be decreased and α/β-tubulin to be increased in the mutation MTUS1 group. The fluorescence intensity of PAR6 was higher and morphology of the daughter cells in the mutation group was different from the wild type group. The phosphorylation of Rac1/Cdc42 in the mutation group was significantly lower than in the wild type group. Conclusions: A de novo mutation in MTUS1 decreased the stability of microtubules and increased cell polarity via the Rac1/Cdc42 pathway, which may partly elucidate the mechanism underlying cellular protection in NVM.

Mitochondrial tumor suppressor 1 is a target of AT-rich interactive domain 1A and progesterone receptor in the murine uterus

Objective

Progesterone receptor (PGR) and AT-rich interactive domain 1A (ARID1A) have important roles in the establishment and maintenance of pregnancy in the uterus. In present studies, we examined the expression of mitochondrial tumor suppressor 1 (MTUS1) in the murine uterus during early pregnancy as well as in response to ovarian steroid hormone treatment.

Methods

We performed quantitative reverse transcription polymerase chain reaction and immunohistochemistry analysis to investigate the regulation of MTUS1 by ARID1A and determined expression patterns of MTUS1 in the uterus during early pregnancy.

Results

The expression of MTUS1 was detected on day 0.5 of gestation (GD 0.5) and then gradually increased until GD 3.5 in the luminal and glandular epithelium. However, the expression of MTUS1 was significantly reduced in the uterine epithelial cells of Pgr^cre/+Arid1a^f/f and Pgr knockout (PRKO) mice at GD 3.5. Furthermore, MTUS1 expression was remarkably induced after P4 treatment in the luminal and glandular epithelium of the wild-type mice. However, the induction of MTUS1 expression was not detected in uteri of Pgr^cre/+Arid1a^f/f or PRKO mice treated with P4.

Conclusion

These results suggest that MTUS1 is a novel target gene by ARID1A and PGR in the uterine epithelial cells.

Microtubule associated tumor suppressor 1 interacts with mitofusins to regulate mitochondrial morphology in endothelial cells

Mitochondria are dynamic organelles that are able to change their morphology and cellular distribution by either fission or fusion. However, the molecular mechanisms controlling mitochondrial dynamics in vascular endothelial cells (ECs) remain largely unknown. In this study, we observed that knockdown of microtubule-associated tumor suppressor 1 (MTUS1) in ECs inhibited tube formation and migration, accompanied with decreased promigratory signalings. We showed that MTUS1 was localized in the outer membrane of mitochondria in ECs. Knockdown of MTUS1 disturbed the elongated mitochondrial network and induced the formation of perinuclear clusters of mitochondria. Importantly, mitochondrial motility and fusion were suppressed, whereas generation of reactive oxygen species was increased in MTUS1 knockdown ECs. Mechanistically, we showed that the N-terminal coiled-coil domain of MTUS1 interacted with the mitochondrial membrane proteins, mitofusin-1 and mitofusin-2, to maintain mitochondrial morphology in ECs. This study illustrated a novel role of MTUS1 in mitochondrial morphology and EC angiogenic responses.-Wang, Y., Huang, Y., Liu, Y., Li, J., Hao, Y., Yin, P., Liu, Z., Chen, J., Wang, Y., Wang, N., Zhang, P. Microtubule associated tumor suppressor 1 interacts with mitofusins to regulate mitochondrial morphology in endothelial cells.

Mitochondrial UQCRB as a new molecular prognostic biomarker of human colorectal cancer

Ubiquinol cytochrome c reductase binding protein (UQCRB) is important for mitochondrial complex III stability, electron transport, cellular oxygen sensing and angiogenesis. However, its potential as a prognostic marker in colorectal cancer (CRC) remains unclear. The aim of this study was to determine whether UQCRB can be used as a diagnostic molecular marker for CRC. The correlation between the expression of three genes (UQCRB, UQCRFS1 and MT-CYB) in the mitochondrial respiratory chain complex III and clinico-pathological features was determined. Compared to non-tumor tissues, UQCRB gene expression was upregulated in CRC tissues. Gene and protein expression of the genes were positively correlated. Copy number variation (CNV) differences in UQCRB were observed in CRC tissues (1.32-fold) compared to non-tumor tissues. The CNV of UQCRB in CRC tissues increased proportionally with gene expression and clinical stage. Single-nucleotide polymorphisms in the 3′-untranslated region of UQCRB (rs7836698 and rs10504961) were investigated, and the rs7836698 polymorphism was associated with CRC clinical stage. DNA methylation of the UQCRB promoter revealed that most CRC patients had high methylation levels (12/15 patients) in CRC tissues compared to non-tumor tissues. UQCRB overexpression and CNV gain were correlated with specific CRC clinico-pathological features, indicating clinical significance as a prognostic predictor in CRC. Gene structural factors may be more important than gene transcription repression factors with respect to DNA methylation in UQCRB overexpression. Our results provide novel insights into the critical role of UQCRB in regulating CRC, supporting UQCRB as a new candidate for the development of diagnostics for CRC patients.

Oncogenic miR-19a and miR-19b co-regulate tumor suppressor MTUS1 to promote cell proliferation and migration in lung cancer

MTUS1 (microtubule-associated tumor suppressor 1) has been identified that can function as a tumor suppressor gene in many malignant tumors. However, the function and mechanisms underlying the regulation of MTUS1 are unclear. In the present study, we reported that miR-19a and miR-19b (miR-19a/b) promote proliferation and migration of lung cancer cells by targeting MTUS1. First, MTUS1 was proved to function as a tumor suppressor in lung cancer and was linked to cell proliferation and migration promotion. Second, an inverse correlation between miR-19a/b expression and MTUS1 mRNA/protein expression was noted in human lung cancer tissues. Third, MTUS1 was appraised as a direct target of miR-19a/b by bioinformatics analysis. Fourth, direct MTUS1 regulation by miR-19a/b in lung cancer cells was experimentally affirmed by cell transfection assay and luciferase reporter assay. Finally, miR-19a/b were shown to cooperatively repress MTUS1 expression and synergistically regulate MTUS1 expression to promote lung cancer cell proliferation and migration. In conclusion, our findings have provided the first clues regarding the roles of miR-19a/b, which appear to function as oncomirs in lung cancer by downregulating MTUS1.

MTUS1 silencing promotes E-selectin production through p38 MAPK-dependent CREB ubiquitination in endothelial cells

BACKGROUND

Endothelial cell activation is thought to be a key event in atherosclerosis. p38 mitogen-activated protein kinase (p38 MAPK) plays an important role in regulating pro-inflammatory cytokine production in endothelial cells (ECs), however, how p38 MAPK is controlled in EC activation remain unclear. In this study, we investigated the effect of mitochondrial tumor suppressor 1 (MTUS1) on p38 MAPK activation, cytokine induction and the underlying molecular mechanisms in ECs.

METHODS AND RESULTS

Using qPCR and ELISA methods, we found that knockdown of MTUS1 led to a marked increase in the mRNA and protein expression of E-selectin (SELE) and monocyte chemotactic protein-1 in ECs, which is accompanied with increased phosphorylation of p38 MAPK (Thr180/Tyr182), MKK3/6 (Ser 189) and IκBα (Ser 32). Using luciferase reporter assay, we found that MTUS1 silencing also activated NF-κB transcriptional activity. The inhibition of p38 MAPK and NF-κB pathway was shown to abrogate MTUS1 silencing-induced cytokine expression in ECs. Furthermore, MTUS1 silencing induced p38 MAPK-dependent ubiquitination of cAMP-response element binding protein (CREB) which potentiated CREB-binding protein-mediated NF-κB p65 acetylation and binding to the promoter of the SELE gene. Conversely, adenovirus-mediated overexpression of MTUS1 inhibited p38 MAPK activation in ECs in vitro and in vivo. Importantly, decreased expression of MTUS1 and CREB, accompanied with induced activation of p38 MAPK were observed in aortas of apoE-/- mice after high-fat diet challenge.

CONCLUSIONS

Our findings showed that MTUS1 regulates the p38 MAPK-mediated cytokine production in ECs. MTUS1 gene probably plays a protective role against pro-inflammatory response of ECs.

Identification of the Mtus1 Splice Variant as a Novel Inhibitory Factor Against Cardiac Hypertrophy

Background

In cardiac hypertrophy and failure, there is a widespread alteration in mRNA splicing, but the role of splice variants in cardiac hypertrophy has not yet been fully elucidated. In this study, we used an exon array to identify novel splice variants associated with cardiac hypertrophy.

Methods and Results

We performed genome‐wide exon array analysis and developed a splicing profile in murine hearts with hypertrophy induced by transverse aortic constriction for 8 weeks. Following global analysis of splice variants using the Mouse Exon 1.0 ST Array, we identified 46 spliced genes and narrowed our focus to 1 gene, mitochondrial tumor suppressor 1 (Mtus1), whose splice variants were registered in the NCBI RefSeq database. Notably, one of the splice variants Mtus1A was specifically upregulated, although the total expression of the Mtus1 gene remained unchanged. We showed that Mtus1A was localized in the mitochondria, and its expression level increased with the degree of cardiac hypertrophy. In cultured cardiomyocytes, Mtus1A overexpression reduced phenylephrine‐induced reactive oxygen species production and consequent ERK phosphorylation, resulting in a decrease in both cell size and protein synthesis. In vivo, cardiac‐specific Mtus1A transgenic mice showed left ventricle wall thinning and a reduced hypertrophic response to pressure overload and phenylephrine treatment.

Conclusions

We found that Mtus1 is specifically spliced in hypertrophic hearts and that the Mtus1A variant has an inhibitory effect on cardiac hypertrophy. Mtus1A is, therefore, a possible diagnostic and therapeutic target for cardiac hypertrophy and failure.

Angiotensin II Type 2 Receptor Inhibits Vascular Intimal Proliferation With Activation of PPARγ

BACKGROUND

Angiotensin II type 2 (AT2) receptor stimulation could exert beneficial effects on vascular remodeling. Previously, we reported that AT2 receptor stimulation ameliorated insulin resistance in diabetic mice accompanied by PPARγ activation which also plays a variety of crucial roles in the vasculature. Therefore, this study aimed to investigate the vascular protective effect of the AT2 receptor with activation of PPARγ involving AT2 receptor-interacting protein (ATIP).

METHODS AND RESULTS

Vascular injury was induced by polyethylene-cuff placement around the femoral artery in C57BL/6J mice. Treatment with compound 21 (C21), an AT2 receptor agonist, decreased neointimal formation, cell proliferation, and the mRNA levels of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor (TNF)-α, and interleukin-1β, and phosphorylation of nuclear factor-kappa B, and increased PPARγ DNA-binding activity in the injured artery, whereas these inhibitory effects of C21 were attenuated by co-treatment with a PPARγ antagonist, GW9662. Treatment of vascular smooth muscle cells (VSMC) with C21 prepared from smAT2 transgenic mice, which highly express the AT2 receptor in VSMC, increased both PPARγ activity and its DNA-binding activity determined by dual-luciferase assay and electrophoresis mobility shift assay (EMSA), respectively. We observed that ATIP was involved in PPARγ complex formation, and that transfection of siRNA of ATIP1 attenuated the AT2 receptor-mediated increase in PPARγ activity in VSMC. In response to AT2 receptor stimulation, ATIP was translocated from the plasma membrane to the nucleus.

CONCLUSIONS

Our results suggest a new mechanism by which AT2 receptor stimulation activates PPARγ, thereby resulting in amelioration of vascular intimal proliferation, and that ATIP plays an important role in AT2 receptor-mediated PPARγ activation.

G protein-coupled receptors as promising cancer targets

G protein-coupled receptors (GPCRs) regulate an array of fundamental biological processes, such as growth, metabolism and homeostasis. Specifically, GPCRs are involved in cancer initiation and progression. However, compared with the involvement of the epidermal growth factor receptor in cancer, that of GPCRs have been largely ignored. Recent findings have implicated many GPCRs in tumorigenesis, tumor progression, invasion and metastasis. Moreover, GPCRs contribute to the establishment and maintenance of a microenvironment which is permissive for tumor formation and growth, including effects upon surrounding blood vessels, signaling molecules and the extracellular matrix. Thus, GPCRs are considered to be among the most useful drug targets against many solid cancers. Development of selective ligands targeting GPCRs may provide novel and effective treatment strategies against cancer and some anticancer compounds are now in clinical trials. Here, we focus on tumor related GPCRs, such as G protein-coupled receptor 30, the lysophosphatidic acid receptor, angiotensin receptors 1 and 2, the sphingosine 1-phosphate receptors and gastrin releasing peptide receptor. We also summarize their tissue distributions, activation and roles in tumorigenesis and discuss the potential use of GPCR agonists and antagonists in cancer therapy.

Loss of Mitochondrial Tumor Suppressor Genes Expression Is Associated with Unfavorable Clinical Outcome in Head and Neck Squamous Cell Carcinoma: Data from Retrospective Study

Mitochondrial genes play important roles in cellular energy metabolism, free radical generation, and apoptosis. Dysregulation of these genes have long been suspected to contribute to the generation of reactive oxygen species (ROS), increased proliferation and progression of cancer. A family of orthologues of yeast silent information regulator 3 (SIRT3), 4 (SIRT4) and mitochondrial tumor suppressor 1 (MTUS1) are important mitochondrial tumor suppressor genes which play an important role in the progression of multiple cancers. However, their role in the development of oxidative stress, enhanced proliferation and progression of head and neck squamous cell carcinoma (HNSCC) has not yet been studied. In this study we aimed to test the association between reduced mitochondrial tumor suppressor genes' activities and enhancement in tissue oxidative stress and cell proliferation in HNSCC cases. The expression of mitochondrial tumor suppressor genes (SIRT3, SIRT4 and MTUS1), mitochondrial DNA repair gene (OGG1-2a) and a proliferation marker (Ki-67) was studied in a study cohort of 120 HNSCC patients and controls with reverse transcriptase polymerase chain reaction (RT-PCR) and real-time PCR (qPCR) in order to determine the potential prognostic significance of these genes. A statistically significant downregulation of SIRT3 (p<0.001), SIRT4 (p<0.0001), MTUS1 (p<0.002) and OGG1 (p<0.0001) was observed in HNSCC compared to control samples. Ki-67 was also overexpressed (p<0.0001) in HNSCC versus control samples. Additionally, to explore gene-gene relationship, we observed a positive spearmen correlation between SIRT3 versus SIRT4 (r = 0.523***, p<0.0001), SIRT3 versus MTUS1 (r = 0.273***, p<0.001), SIRT3 versus OGG1-2a (r = 0.213*, p<0.03), SIRT4 versus OGG1 (r = 0.338***, p<0.0001) and MTUS1 versus OGG1-2a (r = 0.215*, p<0.03) in HNSCC cases. A negative spearman correlation was observed between OGG1 versus Ki-67 (r = -0.224**, p<0.01) and OGG1-2a versus Ki-67 (r = -0.224**, p<0.01) in HNSCC cases. Here we report that the deregulation of mitochondrial tumor suppressor genes (SIRT3, SIRT4 and MTUS1) in relation to decreased expression of mitochondrial DNA repair gene OGG1-2a and increased proliferation (measured by proliferation marker Ki-67) may be considered important factors in the development of head and neck squamous cell carcinoma.

MTUS1 and its targeting miRNAs in colorectal carcinoma: significant associations

Deregulated microRNA (miRNA) expression has been shown to be involved in the pathogenesis of several types of cancers including colorectal cancer (CRC). Thus, determining miRNA targets of genes that play critical role in the malignant transformation is very important. Here, expression levels of tumor suppressor microtubule-associated tumor suppressor 1 (MTUS1) and its regulatory miRNAs were reported. Predicted and validated targets of MTUS1 gene was determined by a computational approach. Expressions of MTUS1 and miRNAs were determined by using 96.96 Dynamic Array™ integrated fluidic circuit (Fluidigm). As a result, MTUS1 levels were found to be diminished in formalin-fixed, paraffin-embedded (FFPE) tissue samples of CRC patients compared to controls. Also, several of MTUS1 targeting miRNAs were found to be upregulated in CRC samples (miR-373-3p, 183-5p, 142-5p, 200c-3p, 19a-3p, -20a-5p, -181a-5p, -184, -181d-5p, -372-3p, 27b-3p, 98-5p, -let-7i-5p, -let-7d-5p, -let-7g-5p, -let-7b-5p, and -let-7c-5p). Of these miRNAs, miR-135b-5p, -373-3p, 183-5p, 142-5p, 200c-3p, 19a-3p showed marked expression levels. In contrast, expression levels of let-7a-5p, 7e-5p, 7f-5p, hsa-miR-125a-5p, and 125b-5p were found to be downregulated in CRC tissues. Accordingly, some of the overexpressed miRNAs especially the miR-135b-5p, -373-3p, 183-5p, 142-5p, 200c-3p, and 19a-3p may play key roles in CRC pathophysiology through MTUS1. In contrast, let-7a-5p, 7e-5p, 7f-5p, miR-125a-5p, and 125b-5p may play important roles in CRC carcinogenesis independent from the MTUS1. In conclusion, MTUS1 targeting miRNAs may play key roles in the development of CRC by downregulating tumor suppressor MTUS1.

Angiotensin II type 2 receptor-interacting protein 3a suppresses proliferation, migration and invasion in tongue squamous cell carcinoma via the extracellular signal-regulated kinase-Snai2 pathway

Our previous studies demonstrated that the downregulation of microtubule-associated tumor suppressor 1/angiotensin II type 2 receptor-interacting protein (MTUS1/ATIP) is associated with poor differentiation and prognosis in tongue squamous cell carcinoma (TSCC), and that ATIP1 exerts an antiproliferative effect on TSCC. The aim of the present study was to further investigate the anticancer effect of MTUS1/ATIP3a in TSCC. It was observed that UM1 cells (a TSCC cell line with high migration and invasion ability) exhibited lower expression of ATIP3a compared with UM2 cells (a TSCC cell line with lower migration and invasion ability). Restoration of ATIP3a expression in UM1 cells exerted antiproliferative effects and inhibited migration and invasion, whereas knockdown of ATIP3a promoted proliferation, migration and invasion in UM2 cells. Restoration of ATIP3a expression inhibited the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and the expression of Snai2 and vimentin in UM1 cells, whereas knockdown of ATIP3a promoted the phosphorylation of ERK1/2 and the expression of Snai2 and vimentin in UM2 cells. Therefore, MTUS1/ATIP3a was found to suppress the proliferation, migration and invasion of TSCC cells via the ERK1/2-Snai2 pathway.

Activation of intracellular angiotensin AT₂ receptors induces rapid cell death in human uterine leiomyosarcoma cells

The presence of angiotensin type 2 (AT₂) receptors in mitochondria and their role in NO generation and cell aging were recently demonstrated in various human and mouse non-tumour cells. We investigated the intracellular distribution of AT₂ receptors including their presence in mitochondria and their role in the induction of apoptosis and cell death in cultured human uterine leiomyosarcoma (SK-UT-1) cells and control human uterine smooth muscle cells (HutSMC). The intracellular levels of the AT₂ receptor are low in proliferating SK-UT-1 cells but the receptor is substantially up-regulated in quiescent SK-UT-1 cells with high densities in mitochondria. Activation of the cell membrane AT₂ receptors by a concomitant treatment with angiotensin II and the AT₁ receptor antagonist, losartan, induces apoptosis but does not affect the rate of cell death. We demonstrate for the first time that the high-affinity, non-peptide AT₂ receptor agonist, Compound 21 (C21), penetrates the cell membrane of quiescent SK-UT-1 cells, activates intracellular AT₂ receptors and induces rapid cell death; approximately 70% of cells died within 24 h. The cells, which escaped cell death, displayed activation of the mitochondrial apoptotic pathway, i.e. down-regulation of the Bcl-2 protein, induction of the Bax protein and activation of caspase-3. All quiescent SK-UT-1 cells died within 5 days after treatment with a single dose of C21. C21 was devoid of cytotoxic effects in proliferating SK-UT-1 cells and in quiescent HutSMC. Our results point to a new, unique approach enabling the elimination non-cycling uterine leiomyosarcoma cells providing that they over-express the AT₂ receptor.

MTUS1/ATIP3a down-regulation is associated with enhanced migration, invasion and poor prognosis in salivary adenoid cystic carcinoma

BACKGROUND

Microtubule-associated tumor suppressor gene (MTUS1) has been identified as tumor suppressor gene in many malignant tumors. In this study, we investigated the role of MTUS1 in the development of salivary adenoid cystic carcinoma (SACC) and its functional effect on the migration and invasion of SACC.

METHODS

Archival clinical samples including 49 primary SACC were examined for MTUS1 expression by immunohistochemistry. Statistical analyses were performed to evaluate the correlation between MTUS1 with histopathological features and survival. The expression of MTUS1/ATIP (AT2 receptor-interacting protein) isoforms was determined in SACC tissue samples and cell lines using quantitative RT-PCR assays. Then we investigated whether the migration and invasion of SACC were mediated by MTUS1/ATIP3a using in vitro cell migration and invasion assay.

RESULTS

We confirmed that the down-regulation of MTUS1 was a frequent event in SACC, and was correlated with distant metastasis and associated with reduced overall survival and disease free survival. Isoform specific quantitative RT-PCR assays revealed that ATIP1, ATIP3a and ATIP3b were the major isoforms of the MTUS1 gene products in SACC, and were significant down-regulation in SACC as compared to matching normal tissues. For functional analyses, we found that SACC-LM cells (SACC cell line with higher migration and invasion ability) possessed a lower expression level of ATIP3a compared to SACC-83 cells (lower migration and invasion ability). Restoration of ATIP3a expression in SACC-LM cells induced anti-proliferative activity and inhibited the migration and invasion ability. Knockdown of ATIP3a promoted the proliferation, migration and invasion ability of SACC-83 cells. Restoration of ATIP3a inhibited the phosphorylation of ERK (extracellular-regulated kinase) 1/2, the expression of Slug and Vimentin in SACC-LM cells, while knockdown of ATIP3a increased the phosphorylation of ERK1/2, the expression of Slug and Vimentin in SACC-83 cells.

CONCLUSIONS

Our studies confirm that MTUS1 plays an important role in the progression of SACC, and may serve as a biomarker or therapeutic target for patients with SACC. MTUS1/ATIP3a down-regulation contributes to the proliferation, migration and the invasion abilities of SACC.

G-protein coupled receptors of the renin-angiotensin system: new targets against breast cancer?

G-protein coupled receptors (GPCRs) constitute the largest family of membrane receptors, with high potential for drug discovery. These receptors can be activated by a panel of different ligands including ions, hormones, small molecules, and vasoactive peptides. Among those, angiotensins [angiotensin II (AngII) and angiotensin 1–7] are the major biologically active products of the classical and alternative renin-angiotensin system (RAS). These peptides bind and activate three different subtypes of GPCRs, namely AT1, AT2, and Mas receptors, to regulate cardiovascular functions. Over the past decade, the contribution of several RAS components in tumorigenesis has emerged as a novel important concept, AngII being considered as harmful and Ang1–7 as protective against cancer. Development of selective ligands targeting each RAS receptor may provide novel and efficient targeted therapeutic strategies against cancer. In this review, we focus on breast cancer to summarize current knowledge on angiotensin receptors (AT1, AT2, and Mas), and discuss the potential use of angiotensin receptor agonists and antagonists in clinics.

Loss of MTUS1/ATIP expression is associated with adverse outcome in advanced bladder carcinomas: data from a retrospective study

Background

Seventy percent of all bladder tumours tend to recur and need intensive surveillance, and a subset of tumours progress to muscle-invasive and metastatic disease. However, it is still difficult to find the adequate treatment for every individual patient as it is a very heterogeneous disease and reliable biomarkers are still missing. In our study we searched for new target genes in the critical chromosomal region 8p and investigated the potential tumour suppressor gene candidate MTUS1/ATIP in bladder cancer.

Methods

MTUS1 was identified to be the most promising deleted target gene at 8p in aCGH analysis with 19 papillary bladder tumours. A correlation with bladder cancer was further validated using immunohistochemistry of 85 papillary and 236 advanced bladder tumours and in functional experiments. Kaplan-Meier analysis and multivariate Cox-regression addressed overall survival (OS) and disease-specific survival (DSS) as a function of MTUS1/ATIP expression. Bivariate correlations investigated associations between MTUS1/ATIP expression, patient characteristics and histopathology. MTUS1 expression was analysed in cell lines and overexpressed in RT112, where impact on viability, proliferation and migration was measured.

Results

MTUS1 protein expression was lost in almost 50% of all papillary and advanced bladder cancers. Survival, however, was only influenced in advanced carcinomas, where loss of MTUS1 was associated with adverse OS and DSS. In this cohort, there was also a significant correlation of MTUS1 expression and histological subtype: positive expression was detected in all micropapillary tumours and aberrant nuclear staining was detected in a subset of plasmocytoid urothelial carcinomas. MTUS1 was expressed in all investigated bladder cell lines and overexpression in RT112 led to significantly decreased viability.

Conclusions

MTUS1 is a tumour suppressor gene in cultured bladder cancer cells and in advanced bladder tumours. It might represent one new target gene at chromosome 8p and can be used as an independent prognostic factor for advanced bladder cancer patients. The limitation of the study is the retrospective data analysis. Thus, findings should be validated with a prospective advanced bladder tumour cohort.

Genetic imbalances detected by multiplex ligation-dependent probe amplification in a cohort of patients with oral squamous cell carcinoma-the first step towards clinical personalized medicine

Oral tumors are a growing health problem worldwide; thus, it is mandatory to establish genetic markers in order to improve diagnosis and early detection of tumors, control relapses and, ultimately, delineate individualized therapies. This study was the first to evaluate and discuss the clinical applicability of a multiplex ligation-dependent probe amplification (MLPA) probe panel directed to head and neck cancer. Thirty primary oral squamous cell tumors were analyzed using the P428 MLPA probe panel. We detected genetic imbalances in 26 patients and observed a consistent pattern of distribution of genetic alterations in terms of losses and gains for some chromosomes, particularly for chromosomes 3, 8, and 11. Regarding the latter, some specific genes were highlighted due to frequent losses of genetic material--RARB, FHIT, CSMD1, GATA4, and MTUS1--and others due to gains--MCCC1, MYC, WISP1, PTK2, CCND1, FGF4, FADD, and CTTN. We also verified that the gains of MYC and WISP1 genes seem to suggest higher propensity of tumors localized in the floor of the mouth. This study proved the value of this MLPA probe panel for a first-tier analysis of oral tumors. The probemix was developed to include target regions that have been already shown to be of diagnostic/prognostic relevance for oral tumors. Furthermore, this study emphasized several of those specific genetic targets, suggesting its importance to oral tumor development, to predict patients' outcomes, and also to guide the development of novel molecular therapies.

Function and expression of ATIP and its variants in cardiomyoblast cell line H9c2

HYPOTHESIS

Cardiac hypertrophy in myocytes is in part regulated by changes in expression of a novel Ang II type 2 receptor (AT2-receptor) interacting protein identified as ATIP.

INTRODUCTION

The role of the AT2-receptor in cardiac hypertrophy is controversial, with some reports indicating that AT2-receptor activation has detrimental effects on disease progression, whereas others indicate that it has a beneficial role.

MATERIALS AND METHODS

In an effort to unravel this paradox, we examined the expression and function of ATIP in cell-based models of cardiac hypertrophy using QPCR, immunohistochemistry, cell proliferation, morphological and transfection techniques in H9c2 cardio-myoblast and myotubules.

RESULTS

These studies indicate that in cultured cardio-myoblast and myotubules, Ang II mediates cellular hypertrophy and proliferation solely via the AT1-receptor, the ATIP variants are abundantly expressed and that ATIP3 may play an anti-proliferative/hypertrophic role in these cells in the absence of AT2-receptor expression or activation.

CONCLUSIONS

Previously ATIP has been shown to inhibit growth factor signalling in cancerous cells via an interaction with the AT2-receptor. This is the first report to identify that ATIP may have a similar role in other disease states characterised by excessive growth and indicates that for ATIP3, at least, an interaction with the AT2-receptor may not be necessary.

Effect of angiotensin II type 2 receptor-interacting protein on adipose tissue function via modulation of macrophage polarization

We demonstrated that angiotensin II type 2 (AT₂) receptor-interacting protein (ATIP) 1 ameliorates inflammation-mediated vascular remodeling independent of the AT₂ receptor, leading us to explore the possibility of whether ATIP1 could exert anti-inflammatory effects and play a role in other pathophysiological conditions. We examined the possible anti-inflammatory effects of ATIP1 in adipose tissue associated with amelioration of insulin resistance. In mice fed a high-cholesterol diet, adipose tissue macrophage (ATM) infiltration and M1-to-M2 ratio were decreased in ATIP1 transgenic mice (ATIP1-Tg) compared with wild-type mice (WT), with decreased expression of inflammatory cytokines such as tumor necrosis factor-α and monocyte chemoattractant protein-1 in white adipose tissue (WAT), but an increase in interleukin-10, an anti-inflammatory cytokine. Moreover, 2-[³H]deoxy-d-glucose (2-[³H]DG) uptake was significantly increased in ATIP1-Tg compared with WT. Next, we examined the roles of ATIP1 in BM-derived hematopoietic cells, employing chimeric mice produced by BM transplantation into irradiated type 2 diabetic mice with obesity, KKAy, as recipients. ATM infiltration and M1-to-M2 ratio were decreased in ATIP1 chimera (ATIP1-tg as BM donor), with improvement of insulin-mediated 2-[³H]DG uptake and amelioration of inflammation in WAT. Moreover, serum adiponectin concentration in ATIP1 chimera was significantly higher than that in WT chimera (WT as BM donor) and KKAy chimera (KKAy as BM donor). These results indicate that ATIP1 could exert anti-inflammatory effects in adipose tissue via macrophage polarization associated with improvement of insulin resistance, and ATIP1 in hematopoietic cells may contribute to these beneficial effects on adipose tissue functions in type 2 diabetes.

ATIP3, a novel prognostic marker of breast cancer patient survival, limits cancer cell migration and slows metastatic progression by regulating microtubule dynamics

Metastasis, a fatal complication of breast cancer, does not fully benefit from available therapies. In this study, we investigated whether ATIP3, the major product of 8p22 MTUS1 gene, may be a novel biomarker and therapeutic target for metastatic breast tumors. We show that ATIP3 is a prognostic marker for overall survival among patients with breast cancer. Notably, among metastatic tumors, low ATIP3 levels associate with decreased survival of the patients. By using a well-defined experimental mouse model of cancer metastasis, we show that ATIP3 expression delays the time-course of metastatic progression and limits the number and size of metastases in vivo. In functional studies, ATIP3 silencing increases breast cancer cell migration, whereas ATIP3 expression significantly reduces cell motility and directionality. We report here that ATIP3 is a potent microtubule-stabilizing protein whose depletion increases microtubule dynamics. Our data support the notion that by decreasing microtubule dynamics, ATIP3 controls the ability of microtubule tips to reach the cell cortex during migration, a mechanism that may account for reduced cancer cell motility and metastasis. Of interest, we identify a functional ATIP3 domain that associates with microtubules and recapitulates the effects of ATIP3 on microtubule dynamics, cell proliferation, and migration. Our study is a major step toward the development of new personalized treatments against metastatic breast tumors that have lost ATIP3 expression.

AT2 Receptor-Interacting Proteins ATIPs in the Brain

A complete renin-angiotensin system (RAS) is locally expressed in the brain and fulfills important functions. Angiotensin II, the major biologically active peptide of the RAS, acts via binding to two main receptor subtypes designated AT1 and AT2. The present paper focuses on AT2 receptors, which have been reported to have neuroprotective effects on stroke, degenerative diseases, and cognitive functions. Our group has identified a family of AT2 receptor interacting proteins (ATIPs) comprising three major members (ATIP1, ATIP3, and ATIP4) with different intracellular localization. Of interest, all ATIP members are expressed in brain tissues and carry a conserved domain able to interact with the AT2 receptor intracellular tail, suggesting a role in AT2-mediated brain functions. We summarize here current knowledge on the ATIP family of proteins, and we present new experimental evidence showing interaction defects between ATIP1 and two mutant forms of the AT2 receptor identified in cases of mental retardation. These studies point to a functional role of the AT2/ATIP1 axis in cognition.

Meta-analysis of gene expression signatures defining the epithelial to mesenchymal transition during cancer progression

The epithelial to mesenchymal transition (EMT) represents a crucial event during cancer progression and dissemination. EMT is the conversion of carcinoma cells from an epithelial to a mesenchymal phenotype that associates with a higher cell motility as well as enhanced chemoresistance and cancer stemness. Notably, EMT has been increasingly recognized as an early event of metastasis. Numerous gene expression studies (GES) have been conducted to obtain transcriptome signatures and marker genes to understand the regulatory mechanisms underlying EMT. Yet, no meta-analysis considering the multitude of GES of EMT has been performed to comprehensively elaborate the core genes in this process. Here we report the meta-analysis of 18 independent and published GES of EMT which focused on different cell types and treatment modalities. Computational analysis revealed clustering of GES according to the type of treatment rather than to cell type. GES of EMT induced via transforming growth factor-β and tumor necrosis factor-α treatment yielded uniformly defined clusters while GES of models with alternative EMT induction clustered in a more complex fashion. In addition, we identified those up- and downregulated genes which were shared between the multitude of GES. This core gene list includes well known EMT markers as well as novel genes so far not described in this process. Furthermore, several genes of the EMT-core gene list significantly correlated with impaired pathological complete response in breast cancer patients. In conclusion, this meta-analysis provides a comprehensive survey of available EMT expression signatures and shows fundamental insights into the mechanisms that are governing carcinoma progression.

Detection of metals and metalloproteins in the plasma of stroke patients by mass spectrometry methods

Stroke is the leading cause of adult disability, worldwide. Metalloproteins and metals play key roles in epigenetic events in living organisms, including hypertension, the most important modifiable risk factor for stroke. Thus, metalloproteins may be important target biomarkers for disease diagnosis. The primary goal of this study was to assess metal containing proteins in blood plasma, detected by ICP-MS, followed by ESIMS for peptide/protein identification. We then compared the relative concentration differences between samples from patients with ischemic stroke, hemorrhagic stroke and stroke mimics. In 29 plasma samples (10 stroke mimics, 10 ischemic stroke and 9 hemorrhagic stroke patients) previously collected from patients who presented to the University of Cincinnati Emergency Department within 12 hours of symptom onset for a plasma banking project. For the metal associated protein study, Mg, Mn, Cu, Se concentrations were statistically different when compared between stroke mimics vs. ischemic stroke patients and ischemic stroke patients vs. hemorrhagic stroke patients. Pb concentrations were statistically different when compared between stroke mimics vs. ischemic stroke patients and Mo levels were statistically the same among the three groups. In addition, we also report concentration levels and preliminary correlation studies for total elemental analysis among the three sets of patients. This pilot study demonstrates that mass spectrometry methods may be highly valuable in detecting novel stroke biomarkers in blood plasma. Expanded studies are warranted to confirm these findings.

Regulation of angiotensin II receptors beyond the classical pathway

The RAS (renin–angiotensin system) plays a role not only in the cardiovascular system, including blood pressure regulation, but also in the central nervous system. AngII (angiotensin II) binds two major receptors: the AT1 receptor (AngII type 1 receptor) and AT2 receptor (AngII type 2 receptor). It has been recognized that AT2 receptor activation not only opposes AT1 receptor actions, but also has unique effects beyond inhibitory cross-talk with AT1 receptor signalling. Novel pathways beyond the classical actions of RAS, the ACE (angiotensin-converting enzyme)/AngII/AT1 receptor axis, have been highlighted: the ACE2/Ang-(1–7) [angiotensin-(1–7)]/Mas receptor axis as a new opposing axis against the ACE/AngII/AT1 receptor axis, novel AngII-receptor-interacting proteins and various AngII-receptor-activation mechanisms including dimer formation. ATRAP (AT1-receptor-associated protein) and ATIP (AT2-receptor-interacting protein) are well-characterized AngII-receptor-associated proteins. These proteins could regulate the functions of AngII receptors and thereby influence various pathophysiological states. Moreover, the possible cross-talk between PPAR (peroxisome-proliferator-activated receptor)-γ and AngII receptor subtypes is an intriguing issue to be addressed in order to understand the roles of RAS in the metabolic syndrome, and interestingly some ARBs (AT1-receptor blockers) have been reported to have an AT1-receptor-blocking action with a partial PPAR-γ agonistic effect. These emerging concepts concerning the regulation of AngII receptors are discussed in the present review.

Reduced expression of MTUS1 mRNA is correlated with poor prognosis in bladder cancer

Mitochondrial tumor suppressor 1 (MTUS1) is a newly identified candidate tumor suppressor gene. Previous studies have demonstrated that the expression status of MTUS1 is altered in several types of tumors. However, its clinical significance for bladder cancer patients remains undetermined. In this study, we detected the expression of MTUS1 mRNA in bladder tumors and paired normal samples obtained from 5 patients using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). A significant downregulation of MTUS1 mRNA expression was observed in the tumor tissues compared with the corresponding normal bladder tissue (P<0.001). We further tested the expression of MTUS1 mRNA in 55 bladder cancer tissues and 10 adjacent normal bladder tissues by quantitative real-time RT-PCR. Correlations between MTUS1 and clinicopathological features and prognosis were investigated by statistical analyses. The results showed that MTUS1 expression was correlated with tumor grade, stage, size and number (P<0.001, P<0.001, P=0.034 and P=0.029, respectively). Patients with low levels of MTUS1 mRNA expression had a poor prognosis compared with those with a high expression (P<0.001). Univariate and multivariate logistic regression prognostic analyses revealed that MTUS1 mRNA was an independent prognostic factor for disease-free survival in bladder cancer (P<0.05). In conclusion, these data suggest that MTUS1 is significant in the progression of bladder cancer and that the status of MTUS1 mRNA expression is a novel prognostic marker for predicting bladder tumor disease-free survival.

Angiotensin II type 2 receptor-interacting protein prevents vascular senescence

Angiotensin II type 2 (AT(2)) receptor-interacting protein (ATIP), which interacts with the C-terminal tail of the AT(2) receptor, regulates the functions of the AT(2) receptor. We have reported that AT(2) receptor stimulation attenuated vascular senescence. Therefore, we examined the possible negative role of ATIP in regulating vascular senescence. We generated ATIP-transgenic (Tg) mice, and cultured vascular smooth muscle cells (VSMCs). Persistent angiotensin II stimulation induced increases in SA-β-gal-positive cells and the level of a DNA damage marker, 8-OHdG in VSMC, whereas these effects of angiotensin II were attenuated in VSMC prepared from ATIP-Tg mice. Angiotensin II treatment also upregulated the expression of methyl methanesulfonate-sensitive 2 (MMS2), a DNA repair factor, and Src homology 2 domain-containing protein-tyrosine phosphatase 1 (SHP-1) activity, whereas these effects of angiotensin II were further enhanced in ATIP-Tg VSMC. In vivo, x-ray irradiation to mice caused increases in SA-β-gal-positive area and 8-OHdG level in the thoracic aorta; however, these effects were reduced in ATIP-Tg mice, with a significant increase in MMS2 expression. These results suggest that ATIP could inhibit VSMC senescence, involving MMS2 expression and SHP-1 activity. ATIP might be a new therapeutic molecule to treat vascular aging and age-related vascular diseases.

Down-regulation of tumor suppressor MTUS1/ATIP is associated with enhanced proliferation, poor differentiation and poor prognosis in oral tongue squamous cell carcinoma

Microtubule-associated tumor suppressor gene (MTUS1, also known as mitochondrial tumor suppressor) is a recently identified tumor suppressor gene that has been implicated in several cancer types. The expression of MTUS1 gene leads to 5 known transcript variants and codes for 5 isoforms of Angiotensin II AT2 receptor interacting protein (ATIP). In this study, we first confirmed that the down-regulation of MTUS1/ATIP was a frequent event in oral tongue squamous cell carcinoma (OTSCC) and the premalignant lesion (leukoplakia). We further demonstrated that the down-regulation of MTUS1/ATIP was correlated with poor differentiation and enhanced proliferation (Ki67 proliferation index). Statistical analysis suggests that the down-regulation of MTUS1/ATIP was associated with reduced overall survival. Isoform specific quantitative RT-PCR assays revealed that ATIP1, ATIP3a and ATIP3b were the major isoforms of the MTUS1 gene products in oral tongue epithelial cells. Significant down-regulations were observed for all 3 ATIP isoforms in OTSCC as compared to matching normal tissues. In vitro functional study showed that the restoration of ATIP1 expression led to G1 arrest, apoptosis and reduction of cell proliferation in OTSCC cell lines. These ATIP1-induced cellular changes were accompanied by reduced phosphorylation of ERK1/2 and up-regulation of p53. Taken together, these data suggest that MTUS1 plays major roles in the progression of OTSCC, and may serve as a biomarker or therapeutic target for patients with OTSCC.

Microtubule associated tumor suppressor 1 deficient mice develop spontaneous heart hypertrophy and SLE-like lymphoproliferative disease

The microtubule associated tumor suppressor gene 1 (MTUS1) is a recently published tumor suppressor gene, which has also been shown to act as an early component in the growth inhibitory signaling cascade of the angiotensin II type 2 receptor (AT2R). In this study we report the generation of MTUS1 knock-out (KO) mice, which develop normally but reveal higher body weights and slightly decreased blood pressure levels. Twenty-eight percent of the studied MTUS1 KO mice also developed heart hypertrophy and 12% developed nephritis, independent of blood pressure levels. Forty-three percent of the MTUS1 KO mice revealed lymphoid hyperplasia affecting spleen (20%), kidney (37%), lung (23%), lymph nodes (17%), and liver (17%) accompanied with leukocytosis, lymphocytosis, and mild anemia. One animal (3%) developed a marginal zone B-cell lymphoma affecting submandibular salivary gland and regional lymph nodes. The symptoms of all mentioned animals are consistent with a B-cell lymphoproliferative disease with features of systemic lupus erythematosus. In addition, body weight of the MTUS1 KO mice was significantly increased and isolated skin fibroblasts showed increased cell proliferation and decreased cell size, compared to wild-type (WT) fibroblasts in response to depleted FCS concentration and lack of growth factors. In conclusion we herein report the first generation of a MTUS1 KO mouse, developing spontaneous heart hypertrophy and increased cell proliferation, confirming once more the anti-proliferative effect of MTUS1, and a SLE-like lymphoproliferative disease suggesting crucial role in regulation of inflammation. These MTUS1 KO mice can therefore serve as a model for further investigations in cardiovascular disease, autoimmune disease and carcinogenesis.