Protein interacting with C alpha kinase 1 (PICK1) is involved in promoting tumor growth and correlates with poor prognosis of human breast cancer

Multi-omics study identifies that PICK1 deficiency causes male infertility by inhibiting vesicle trafficking in Sertoli cells

BACKGROUND

Infertility affects approximately 10-15% of reproductive-age men worldwide, and genetic causes play a role in one-third of cases. As a Bin-Amphiphysin-Rvs (BAR) domain protein, protein interacting with C-kinase 1 (PICK1) deficiency could lead to impairment of acrosome maturation. However, its effects on auxiliary germ cells such as Sertoli cells are unknown.

PURPOSE

The present work was aimed to use multi-omics analysis to research the effects of PICK1 deficiency on Sertoli cells and to identify effective biomarkers to distinguish fertile males from infertile males caused by PICK1 deficiency.

METHODS

Whole-exome sequencing (WES) was performed on 20 infertility patients with oligozoospermia to identify pathogenic PICK1 mutations. Multi-omics analysis of a PICK1 knockout (KO) mouse model was utilized to identify pathogenic mechanism. Animal and cell function experiments of Sertoli cell-specific PICK1 KO mouse were performed to verify the functional impairment of Sertoli cells.

RESULTS

Two loss-of-function deletion mutations c.358delA and c.364delA in PICK1 resulting in transcription loss of BAR functional domain were identified in infertility patients with a specific decrease in serum inhibin B, indicating functional impairment of Sertoli cells. Multi-omics analysis of PICK1 KO mouse illustrated that targeted genes of differentially expressed microRNAs and mRNAs are significantly enriched in the negative regulatory role in the vesicle trafficking pathway, while metabolomics analysis showed that the metabolism of amino acids, lipids, cofactors, vitamins, and endocrine factors changed. The phenotype of PICK1 KO mouse showed a reduction in testis volume, a decreased number of mature spermatozoa and impaired secretory function of Sertoli cells. In vitro experiments confirmed that the expression of growth factors secreted by Sertoli cells in PICK1 conditional KO mouse such as Bone morphogenetic protein 4 (BMP4) and Fibroblast growth factor 2 (FGF2) were decreased.

CONCLUSIONS

Our study attributed male infertility caused by PICK1 deficiency to impaired vesicle-related secretory function of Sertoli cells and identified a variety of significant candidate biomarkers for male infertility induced by PICK1 deficiency.

The Scaffold Protein PICK1 as a Target in Chronic Pain

Well-tolerated and effective drugs for treating chronic pain conditions are urgently needed. Most chronic pain patients are not effectively relieved from their pain and suffer from debilitating drug side effects. This has not only drastic negative consequences for the patients’ quality of life, but also constitute an enormous burden on society. It is therefore of great interest to explore new potent targets for effective pain treatment with fewer side effects and without addiction liability. A critical component of chronic pain conditions is central sensitization, which involves the reorganization and strengthening of synaptic transmission within nociceptive pathways. Such changes are considered as maladaptive and depend on changes in the surface expression and signaling of AMPA-type glutamate receptors (AMPARs). The PDZ-domain scaffold protein PICK1 binds the AMPARs and has been suggested to play a key role in these maladaptive changes. In the present paper, we review the regulation of AMPARs by PICK1 and its relation to pain pathology. Moreover, we highlight other pain-relevant PICK1 interactions, and we evaluate various compounds that target PICK1 and have been successfully tested in pain models. Finally, we evaluate the potential on-target side effects of interfering with the action of PICK1 action in CNS and beyond. We conclude that PICK1 constitutes a valid drug target for the treatment of inflammatory and neuropathic pain conditions without the side effects and abuse liability associated with current pain medication.

Protein interacting with C-kinase 1 is involved in epithelial-mesenchymal transformation and suppresses progress of gastric cancer

Protein interacting with C-kinase 1 (PICK1) is a 415-aa multidomain scaffold protein encoded by the PICK1 gene. Accumulating evidence suggests that PICK1 is involved in the progression of cancer. However, the role of PICK1 in gastric cancer (GC) remains largely unknown. Using integrated analysis of publicly available GC transcriptome data from the Gene Expression Omnibus (GEO) database and immunohistochemistry analysis of samples obtained from clinical GC patients, we found that PICK1 expression was significantly down-regulated in gastric tumor tissues in comparison with adjacent normal tissues. Our analyses also revealed that decreased expression of PICK1 conferred a disadvantage on overall survival time in GC patients. Additionally, PICK1 expression showed a strong association with the epithelial-mesenchymal transition (EMT) pathway, and PICK1 might represent a functional bridge for EMT. Moreover, PICK1 expression was significantly decreased in the EMT subtype of GC and was negatively correlated with the expression of fibronectin 1 (FN1) and myosin light chain 9 (MYL9) mRNAs. Thus, our study provides evidence that PICK1 is a promising biomarker for the molecular etiology of GC.

miR-615-3p promotes the epithelial-mesenchymal transition and metastasis of breast cancer by targeting PICK1/TGFBRI axis

Background

Increasing evidence indicates that epithelial-mesenchymal transition (EMT) can be regulated by microRNAs (miRNAs). miR-615-3p was shown to be involved in tumor development. However, the role of miR-615-3p in the metastasis of breast cancer remains largely unknown.

Methods

The expression of miR-615-3p in breast cancer cells and tissues was assessed by qRT-PCR and situ hybridization assays. Effects of miR-615-3p on tumor metastasis were evaluated with experiments in vitro and mouse model. EMT markers were detected by western blot and immunofluorescence assays. Molecular mechanism of miR-615-3p in the regulation of breast cancer cell metastasis was analyzed by Western Blot, Co-immunoprecipitation, and Luciferase assay.

Results

In the present study, we found that miR-615-3p was significantly elevated in breast cancer cells and tissues, especially in those with metastasis. In breast cancer cell lines, stable overexpression of miR-615-3p was sufficient to promote cell motility in vitro, and pulmonary metastasis in vivo, accompanied by the reduced expression of epithelial markers and the increased levels of mesenchymal markers. Further studies revealed that the reintroduction of miR-615-3p increased the downstream signaling of TGF-β, the type I receptor (TGFBRI) by targeting the 3′-untranslated regions (3′-UTR) of PICK1. PICK1 inhibits the binding of DICER1 to Smad2/3 and the processing of pre-miR-615-3p to mature miR-615-3p in breast cancer cells, thus exerting a negative feedback loop.

Conclusions

Our data highlight an important role of miR-615-3p in the molecular etiology of breast cancer, and implicate the potential application of miR-615-3p in cancer therapy.

Cellular and pathophysiological consequences of Arp2/3 complex inhibition: role of inhibitory proteins and pharmacological compounds

The actin-related protein complex 2/3 (Arp2/3) generates branched actin networks important for many cellular processes such as motility, vesicular trafficking, cytokinesis, and intercellular junction formation and stabilization. Activation of Arp2/3 requires interaction with actin nucleation-promoting factors (NPFs). Regulation of Arp2/3 activity is achieved by endogenous inhibitory proteins through direct binding to Arp2/3 and competition with NPFs or by binding to Arp2/3-induced actin filaments and disassembly of branched actin networks. Arp2/3 inhibition has recently garnered more attention as it has been associated with attenuation of cancer progression, neurotoxic effects during drug abuse, and pathogen invasion of host cells. In this review, we summarize current knowledge on expression, inhibitory mechanisms and function of endogenous proteins able to inhibit Arp2/3 such as coronins, GMFs, PICK1, gadkin, and arpin. Moreover, we discuss cellular consequences of pharmacological Arp2/3 inhibition.

The Arp2/3 Regulatory System and Its Deregulation in Cancer

The Arp2/3 complex is an evolutionary conserved molecular machine that generates branched actin networks. When activated, the Arp2/3 complex contributes the actin branched junction and thus cross-links the polymerizing actin filaments in a network that exerts a pushing force. The different activators initiate branched actin networks at the cytosolic surface of different cellular membranes to promote their protrusion, movement, or scission in cell migration and membrane traffic. Here we review the structure, function, and regulation of all the direct regulators of the Arp2/3 complex that induce or inhibit the initiation of a branched actin network and that controls the stability of its branched junctions. Our goal is to present recent findings concerning novel inhibitory proteins or the regulation of the actin branched junction and place these in the context of what was previously known to provide a global overview of how the Arp2/3 complex is regulated in human cells. We focus on the human set of Arp2/3 regulators to compare normal Arp2/3 regulation in untransformed cells to the deregulation of the Arp2/3 system observed in patients affected by various cancers. In many cases, these deregulations promote cancer progression and have a direct impact on patient survival.

The TGF-β signalling negative regulator PICK1 represses prostate cancer metastasis to bone

Backgroud:

Constitutive activation of TGF-β signalling is a well-recognised mechanism in bone metastasis of prostate cancer (PCa). Protein Interacting with PRKCA 1 (PICK1) is a critical negative regulator of the TGF-β pathway. However, the clinical significance and biological role of PICK1 in PCa bone metastasis remain obscure.

Methods:

PICK1 expression is evaluated by immunohistochemistry (IHC) in 198 PCa patients. Statistical analysis is performed to explore correlation between PICK1 expression and clinicopathological features in PCa patients. The biological role of PICK1 is examined in PC-3 and C4-2B cells in vitro and a mouse intracardial model in vivo.

Results:

PICK1 expression is decreased in PCa tissues with bone metastasis and bone-derived cells and downregulation of PICK1 positively correlates with serum PSA level, Gleason grade and bone metastasis status in PCa patients. Overexpression of PICK1 suppresses PCa cell invasion and migration in vitro and bone metastasis in vivo. Our results further indicate downregulation of PICK1 is caused by miR-210-3p overexpression in PCa tissues with bone metastasis. Clinical negative correlation of PICK1 with miR-210-3p is confirmed in PCa tissues.

Conclusions:

Our findings uncover a novel functionally and clinically relevant epigenetic regulatory mechanism for constitutive activation of TGF-β signalling in bone metastasis of PCa.

PICK1 confers anti-inflammatory effects in acute liver injury via suppressing M1 macrophage polarization

Protein interacting with C kinase 1 (PICK1) is a scaffolding protein mainly implicated in neurological diseases, however, the function of PICK1 in acute liver injury (ALI) remains unknown. Our study found a dramatical decrease in mRNA and protein levels of PICK1 in liver tissues and isolated Kupffer cells (KCs) from the liver in mice with ALI. Furthermore, pretreatment the mice with ALI with FSC-231, a pharmacological inhibitor of PICK1, could significantly augment inflammatory response. Furthermore, in vitro studies showed that both lipopolysaccharide (LPS) and interferon gamma (IFN-γ) significantly reduced the expression of PICK1, while IL-4 elevated its expression in RAW 264.7 cells. Additionally, over-expression of PICK1 inhibited the expression of M1 biomarkers by suppressing NF-κB activity, and enhanced the expression of M2 biomarkers by promoting STAT6 activity. In contrast, knockdown of PICK1 or FSC-231 pretreatment promoted M1 polarization and suppressed M2 polarization. Besides, caveolin-1 was identified as a potential target gene controlled by PICK1 in RAW 264.7 cells. Mechanistic investigation revealed a dual role of PICK1 in regulating macrophage polarization and implied PICK1 as a potential therapeutic target in ALI.

Protein interacting with C kinase 1 suppresses invasion and anchorage-independent growth of astrocytic tumor cells

Astrocytic tumors are the most common form of primary brain tumor. Astrocytic tumor cells infiltrate the surrounding CNS tissue, allowing them to evade removal upon surgical resection of the primary tumor. Dynamic changes to the actin cytoskeleton are crucial to cancer cell invasion, but the specific mechanisms that underlie the particularly invasive phenotype of astrocytic tumor cells are unclear. Protein interacting with C kinase 1 (PICK1) is a PDZ and BAR domain-containing protein that inhibits actin-related protein 2/3 (Arp2/3)-dependent actin polymerization and is involved in regulating the trafficking of a number of cell-surface receptors. Here we report that, in contrast to other cancers, PICK1 expression is down-regulated in grade IV astrocytic tumor cell lines and also in clinical cases of the disease in which grade IV tumors have progressed from lower-grade tumors. Exogenous expression of PICK1 in the grade IV astrocytic cell line U251 reduces their capacity for anchorage-independent growth, two-dimensional migration, and invasion through a three-dimensional matrix, strongly suggesting that low PICK1 expression plays an important role in astrocytic tumorigenesis. We propose that PICK1 negatively regulates neoplastic infiltration of astrocytic tumors and that manipulation of PICK1 is an attractive possibility for therapeutic intervention.

Regulation of TGF-β Signal Transduction

Transforming growth factor-β (TGF-β) signaling regulates diverse cellular processes, including cell proliferation, differentiation, apoptosis, cell plasticity, and migration. TGF-β signaling can be mediated by Smad proteins or other signaling proteins such as MAP kinases and Akt. TGF-β signaling is tightly regulated at different levels along the pathways to ensure its proper physiological functions in different cells and tissues. Deregulation of TGF-β signaling has been associated with various kinds of diseases, such as cancer and tissue fibrosis. This paper focuses on our recent work on regulation of TGF-β signaling.

A supervised network analysis on gene expression profiles of breast tumors predicts a 41-gene prognostic signature of the transcription factor MYB across molecular subtypes

Background. MYB is predicted to be a favorable prognostic predictor in a breast cancer population. We proposed to find the inferred mechanism(s) relevant to the prognostic features of MYB via a supervised network analysis. Methods. Both coefficient of intrinsic dependence (CID) and Galton Pierson's correlation coefficient (GPCC) were combined and designated as CIDUGPCC. It is for the univariate network analysis. Multivariate CID is for the multivariate network analysis. Other analyses using bioinformatic tools and statistical methods are included. Results. ARNT2 is predicted to be the essential gene partner of MYB. We classified four prognostic relevant gene subpools in three breast cancer cohorts as feature types I–IV. Only the probes in feature type II are the potential prognostic feature of MYB. Moreover, we further validated 41 prognosis relevant probes to be the favorable prognostic signature. Surprisingly, two additional family members of MYB are elevated to promote poor prognosis when both levels of MYB and ARNT2 decline. Both MYBL1 and MYBL2 may partially decrease the tumor suppressive activities that are predicted to be up-regulated by MYB and ARNT2. Conclusions. The major prognostic feature of MYB is predicted to be determined by the MYB subnetwork (41 probes) that is relevant across subtypes.

PPARδ promotes oncogenic redirection of TGF-β1 signaling through the activation of the ABCA1-Cav1 pathway

TGF-β1 plays biphasic functions in prostate tumorigenesis, inhibiting cell growth at early stages but promoting malignant progression at later stages. However, the molecular basis for the oncogenic conversion of TGF-β1 function remains largely undefined. Here, we demonstrate that PPARδ is a direct transcription target of TGF-β1 and plays a critical role in oncogenic redirection of TGF-β1 signaling. Blockade of PPARδ induction enhances tumor cell response to TGF-β1-mediated growth inhibition, while its activation promotes TGF-β1-induced tumor growth, migration and invasion. PPARδ-mediated switch of TGF-β1 function is associated with down- and upregulation of Smad and ERK signaling, respectively, and tightly linked to its function to activate ABCA1 cholesterol transporter followed by caveolin-1 (Cav1) induction. Intriguingly, TGF-β1 activation of the PPARδ-ABCA1-Cav1 pathway facilitates degradation of TGF-β receptors (TβRs) and attenuates Smad but enhances ERK response to TGF-β1. Expression of PPARδ and Cav1 is tightly correlated in both prostate tissues and cell lines and significantly higher in cancer vs. normal tissues. Collectively, our study shows that PPARδ is a transcription target of TGF-β1 and contributes to the oncogenic conversion of TGF-β1 function through activation of the ABCA1-Cav1-TβR signaling axis.

Clinicopathological significance of NMIIA overexpression in human gastric cancer

Altered expressions of nonmuscle myosin IIA (NMIIA) have been observed in certain types of cancers, but the impact of the alterations in gastric cancer (GC) remains unclear. The purpose of this study was to evaluate the expression of NMIIA at the mRNA and protein level in patients with GC and to assess its clinical significance. We investigated the expression of NMIIA in fresh, paired GC tissues by reverse transcriptase polymerase chain reaction (RT-PCR; n = 14) and Western blot analysis (n = 36). Simultaneously, we performed immunohistochemistry (IHC) on paraffin embedded specimens, including 96 GC specimens, 30 matched normal specimens and 30 paired metastatic lymph node samples. NMIIA is overexpressed in GC compared with the adjacent normal gastric epithelium (p < 0.001) and high-level NMIIA expression is significantly correlated with the depth of wall invasion, lymph node metastasis, distant metastasis and Tumor Node Metastasis (TNM) stage. Furthermore, elevated NMIIA expression is an independent prognostic factor in multivariate analysis using the Cox regression model (p = 0.021). These findings indicate that overexpression of NMIIA may contribute to the progression and poor prognosis of GC.

PICK1 promotes caveolin-dependent degradation of TGF-β type I receptor

Protein that interacts with C kinase 1 (PICK1) is a critical mediator of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) trafficking in neural synapses. However, its ubiquitous expression suggests that it may have other non-neural functions. Here we show that PICK1 antagonizes transforming growth factor beta (TGF-β) signaling by targeting TGF-β type I receptor (TβRI) for degradation. Biochemical analyses reveal that PICK1 directly interacts with the C-terminus of TβRI via its PDZ domain and acts as a scaffold protein to enhance the interaction between TβRI and caveolin-1, leading to enhanced lipid raft/caveolae localization. Therefore, PICK1 increases caveolin-mediated endocytosis, ubiquitination and degradation of TβRI. Moreover, a negative correlation between PICK1 expression and TβRI or phospho-Smad2 levels is observed in human breast tumors, indicating that PICK1 may participate in breast cancer development through inhibition of TGF-β signaling. Our findings reveal a non-neural function of PICK1 as an important negative regulator of TGF-β signaling.

High RIN1 expression is associated with poor prognosis in patients with gastric adenocarcinoma

The aim of this study was to investigate the expression and prognostic significance of RIN1 in gastric adenocarcinoma. RIN1 expression was analyzed using quantitative real-time PCR (qRT-PCR), Western blotting, and immunohistochemical staining on tissue samples from a consecutive series of 315 gastric adenocarcinoma patients who underwent tumor resections between 2003 and 2006. The relationship between RIN1 expression, clinicopathological factors, and patient survival was investigated. qRT-PCR results showed that the RIN1 mRNA expression was higher in tumor tissue samples than in the adjacent normal tissues, and a corresponding increase in protein expression was confirmed by Western blotting. Immunohistochemical staining indicated that RIN1 is highly expressed in 54.3 % of gastric adenocarcinomas. RIN1 expression levels were closely associated with tumor size, histological differentiation, tumor stage, and lymph node involvement. Kaplan-Meier survival analysis showed that high RIN1 expression exhibited a significant correlation with poor prognosis for gastric adenocarcinoma patients. Multivariate analysis revealed that RIN1 expression is an independent prognostic parameter for the overall survival rate of gastric adenocarcinoma patients. Our data suggest that RIN1 plays an important role in gastric adenocarcinoma progression and that a high RIN1 expression predicts an unfavorable prognosis in gastric adenocarcinoma patients.

High RIN1 expression is associated with poor prognosis in patients with gastric adenocarcinoma

The aim of this study was to investigate the expression and prognostic significance of RIN1 in gastric adenocarcinoma. RIN1 expression was analyzed using quantitative real-time PCR (qRT-PCR), Western blotting, and immunohistochemical staining on tissue samples from a consecutive series of 315 gastric adenocarcinoma patients who underwent tumor resections between 2003 and 2006. The relationship between RIN1 expression, clinicopathological factors, and patient survival was investigated. qRT-PCR results showed that the RIN1 mRNA expression was higher in tumor tissue samples than in the adjacent normal tissues, and a corresponding increase in protein expression was confirmed by Western blotting. Immunohistochemical staining indicated that RIN1 is highly expressed in 54.3 % of gastric adenocarcinomas. RIN1 expression levels were closely associated with tumor size, histological differentiation, tumor stage, and lymph node involvement. Kaplan-Meier survival analysis showed that high RIN1 expression exhibited a significant correlation with poor prognosis for gastric adenocarcinoma patients. Multivariate analysis revealed that RIN1 expression is an independent prognostic parameter for the overall survival rate of gastric adenocarcinoma patients. Our data suggest that RIN1 plays an important role in gastric adenocarcinoma progression and that a high RIN1 expression predicts an unfavorable prognosis in gastric adenocarcinoma patients.

Serine 77 in the PDZ domain of PICK1 is a protein kinase Cα phosphorylation site regulated by lipid membrane binding

PICK1 (protein interacting with C kinase 1) contains an N-terminal protein binding PDZ domain and a C-terminal lipid binding BAR domain. PICK1 plays a key role in several physiological processes, including synaptic plasticity. However, little is known about the cellular mechanisms governing the activity of PICK1 itself. Here we show that PICK1 is a substrate in vitro both for PKCα (protein kinase Cα), as previously shown, and for CaMKIIα (Ca(2+)-calmodulin-dependent protein kinase IIα). By mutation of predicted phosphorylation sites, we identify Ser77 in the PDZ domain as a major phosphorylation site for PKCα. Mutation of Ser77 reduced the level of PKCα-mediated phosphorylation ~50%, whereas no reduction was observed upon mutation of seven other predicted sites. Addition of lipid vesicles increased the level of phosphorylation of Ser77 10-fold, indicating that lipid binding is critical for optimal phosphorylation. Binding of PKCα to the PICK1 PDZ domain was not required for phosphorylation, but a PDZ domain peptide ligand reduced the overall level of phosphorylation ~30%. The phosphomimic S77D reduced the extent of cytosolic clustering of eYFP-PICK1 in COS7 cells and thereby conceivably its lipid binding and/or polymerization capacity. We propose that PICK1 is phosphorylated at Ser77 by PKCα preferentially when bound to membrane vesicles and that this phosphorylation in turn modulates its cellular distribution.

Expression of elongation factor (EF)-Tu is correlated with prognosis of gastric adenocarcinomas

Altered expressions of mitochondria elongation factor Tu (EF-Tu) have been observed in certain types of cancers, including gastric cancer cell lines, but the impact of the alterations in gastric adenocarcinoma remains unclear. The purpose of this study was to investigate the expression of EF-Tu in gastric adenocarcinoma and to assess its clinical significance. A total of 104 paired resected gastric adenocarcinoma and corresponding normal specimens were collected in this study. EF-Tu expression was assessed by immunohistochemical staining. The correlation of EF-Tu expression and patients’ clinicopathological parameters was statically evaluated and the prognostic significance of EF-Tu expression was assessed by univariate and multivariate analyses. Forty-nine out of 104 (47.1%) gastric adenocarcinoma specimens showed high expression of EF-Tu, while the remaining 55 specimens showed weak or negative expression of EF-Tu. In contrast, EF-Tu high expression was detected in 62.5% (65 of 104) normal tissues. Down-regulation of EF-Tu was associated with serosal invasion (P = 0.042) and node involvement (P = 0.005), and down-regulation of EF-Tu was correlated with poor overall survival (P = 0.020). In curative resection (R0) patients, there were also significant differences (P = 0.043). In the multivariate analysis, the EF-Tu expression remained a significant independent prognostic factor (P = 0.038). Our results indicate that EF-Tu is expressed in both gastric adenocarcinoma and corresponding normal tissues. Down-regulation of EF-Tu expression is associated with advanced disease stage and EF-Tu expression maybe served as an independent prognostic factor.