Downregulation of ABI1 expression affects the progression and prognosis of human gastric carcinoma

Adaptor protein Abelson interactor 1 in homeostasis and disease

Dysregulation of Abelson interactor 1 (ABI1) is associated with various states of disease including developmental defects, pathogen infections, and cancer. ABI1 is an adaptor protein predominantly known to regulate actin cytoskeleton organization processes such as those involved in cell adhesion, migration, and shape determination. Linked to cytoskeleton via vasodilator-stimulated phosphoprotein (VASP), Wiskott-Aldrich syndrome protein family (WAVE), and neural-Wiskott-Aldrich syndrome protein (N-WASP)-associated protein complexes, ABI1 coordinates regulation of various cytoplasmic protein signaling complexes dysregulated in disease states. The roles of ABI1 beyond actin cytoskeleton regulation are much less understood. This comprehensive, protein-centric review describes molecular roles of ABI1 as an adaptor molecule in the context of its dysregulation and associated disease outcomes to better understand disease state-specific protein signaling and affected interconnected biological processes.

Pan-cancer transcriptomic data of ABI1 transcript variants and molecular constitutive elements identifies novel cancer metastatic and prognostic biomarkers

BACKGROUND

Abelson interactor 1 (ABI1) is associated with the metastasis and prognosis of many malignancies. The association between ABI1 transcript spliced variants, their molecular constitutive exons and exon-exon junctions (EEJs) in 14 cancer types and clinical outcomes remains unsolved.

OBJECTIVE

To identify novel cancer metastatic and prognostic biomarkers from ABI1 total mRNA, TSVs, and molecular constitutive elements.

METHODS

Using data from TCGA and TSVdb database, the standard median of ABI1 total mRNA, TSV, exon, and EEJ expression was used as a cut-off value. Kaplan-Meier analysis, Chi-squared test (X2) and Kendall's tau statistic were used to identify novel metastatic and prognostic biomarkers, and Cox regression analysis was performed to screen and identify independent prognostic factors.

RESULTS

A total of 35 ABI1-related factors were found to be closely related to the prognosis of eight candidate cancer types. A total of 14 ABI1 TSVs and molecular constitutive elements were identified as novel metastatic and prognostic biomarkers in four cancer types. A total of 13 ABI1 molecular constitutive elements were identified as independent prognostic biomarkers in six cancer types.

CONCLUSIONS

In this study, we identified 14 ABI1-related novel metastatic and prognostic markers and 21 independent prognostic factors in total 8 candidate cancer types.

Comprehensive pan-cancer investigation: unraveling the oncogenic, prognostic, and immunological significance of Abelson interactor family member 3 gene in human malignancies

Background: Abelson interactor Family Member 3 (ABI3) encodes protein that not only suppresses the ectopic metastasis of tumor cells but also hinders their migration. Although ABI3 had been found to modulate the advancement of diverse neoplasms, there is no comprehensive pan-cancer analysis of its effects. Methods: The transcriptomics data of neoplasm and normal tissues were retrieved from the Genomic Data Commons (GDC) data portal, and UCSC XENA database. To gather protein information for ABI3, Human Protein Atlas (HPA) and GeneMANIA websites were utilized. Additionally, Tumor Immune Single-cell Hub (TISCH) database was consulted to determine the primary cell types expressing ABI3 in cancer microenvironments. Univariate Cox regression approach was leveraged to evaluate ABI3's prognostic role across cancers. The Cbioportal and Gene Set Cancer Analysis (GSCA) website were leveraged to scrutinize the genomic landscape information across cancers. TIMER2.0 was leveraged to probe the immune cell infiltrations associated with ABI3 across cancers. The associations of ABI3 with immune-related genes were analyzed through Spearman correlation method. Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) were utilized to search associated biological pathways. The CellMiner database and molecular docking were implemented to identify potential interactions between the ABI3 protein and specific anticarcinogen. Findings: ABI3 expression and its ability to predict prognosis varied distinct tumor, with particularly high expression observed in Tprolif cells and monocytes/macrophages. Copy number variation (CNV) and methylation negatively correlated with ABI3 expression in the majority of malignancies. Corresponding mutation survival analysis indicated that the mutation status of ABI3 was strongly connected to the prognosis of LGG patients. ABI3 expression was linked to immunotherapeutic biomarkers and response in cancers. ESTIMATE and immune infiltrations analyses presented ABI3 association with immunosuppression. ABI3 was significantly correlated with immunoregulators and immune-related pathways. Lastly, prospective ABI3-targeted drugs were filtered and docked to ABI3 protein. Interpretation: Our study reveals that ABI3 acts as a robust tumor biomarker. Its functions are vital that could inhibit ectopic metastasis of tumor cells and modulate cellular adhesion and migration. The discoveries presented here may have noteworthy consequences for the creation of fresh anticancer suppressors, especially those targeting BRCA.

A Novel and Validated 8-Pyroptosis-Related Genes Based Risk Prediction Model for Diffuse Large B Cell Lymphoma

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL), the most common type of Non-Hodgkin's Lymphoma (NHL), has a lethal nature. Thus, the establishment of a novel model to predict the prognosis of DLBCL and guide its therapy is an urgency. Meanwhile, pyroptosis is engaged in the progression of DLBCL with further investigations required to reveal the underlying mechanism.

METHODS

LASSO regression was conducted to establish a risk model based on those PRGs. External datasets, RT-qPCR and IHC images from The Human Protein Alta (HPA) database were utilized to validate the model. ssGSEA was utilized to estimate the score of immune components in DLBCL.

RESULTS

A model based on 8 PRGs was established to generate a risk score. Validation of the model confirmed its robust performance. The risk score was associated with advanced clinical stages and shorter overall survivals. Two novel second-line chemotherapies were found to be potential treatments for high-risk patients. The risk score was also found to be correlated with immune components in DLBCL.

CONCLUSION

This novel model can be utilized in clinical practices to predict the prognosis of DLBCL and guide the treatment of patients at high risk, providing an overview of immune regulatory program via pyroptosis in DLBCL.

ABL1 Is a Prognostic Marker and Associated with Immune Infiltration in Hepatocellular Carcinoma

Background

The role of ABL1 in hepatocellular carcinoma (HCC) is still unclear. Therefore, this study aims to explore the potential role of ABL1 in the progression of HCC using bioinformatics methods.

Methods

We analyzed the expression, prognostic potential, and immune cell effect of ABL1 in HCC by using a variety of datasets.

Results

ABL1 is highly expressed in HCC and associated with unfavorable overall survival (OS) and disease-free survival (DFS). Functional network analysis revealed that ABL1 plays an important role in mitochondrial activity, ATP metabolism, protein translation and metabolism, various neurological diseases, nonalcoholic fatty liver disease, and notch signaling pathway. In addition, we found that ABL1 expression was closely correlated with B cells, CD8 + T cells, CD4 + T cells, macrophages, neutrophils, and dendritic cells. Furthermore, ABL1 expression was positively associated with the expression levels of immune checkpoint genes, such as PD-1L, TIM3, TIGIT, and CTLA4.

Conclusion

ABL1 is associated with immune infiltration and prognosis of HCC.

Construction of Two Alternative Polyadenylation Signatures to Predict the Prognosis of Sarcoma Patients

Background

Increasing evidence indicates that alternative polyadenylation (APA) is associated with the prognosis of cancers.

Methods

We obtained gene expression and APA profiles of 259 sarcoma patients from the TCGA dataportal and TC3A database, respectively. The prognostic signatures, clinical nomograms, and regulatory networks were studied by integrated bioinformatics analyses. Then, the immune cell infiltration profile was obtained from the ImmuCellAI. The association between APA-based signature and immune cells was studied.

Results

A total of 61 and 38 APA events were identified as overall survival (OS)- and progress free-survival (PFS)-related biomarkers, respectively. Two signatures were generated. The area under the curves (AUC) values of OS signature were 0.900, 0.928, and 0.963 over 2-, 4-, and 6-years, respectively. And the AUC values of PFS signature at 2-, 4-, and 6-years were 0.826, 0.840, and 0.847, respectively. Overall and subgroup analyses indicated that high-risk patients had a worse prognosis than low-risk patients (all p-values < 0.05). In addition, immunomics analyses indicated that there are different patterns of immune cell infiltration between low- and high-risk patients. Furthermore, two clinical-APA nomograms were established and the C-indexes were 0.813 and 0.809 for OS nomogram and PFS nomogram, respectively. Finally, two APA regulatory networks were constructed. FIP1L1-VPS26B was identified as a key regulating relationship and validated in the pan-cancer analyses.

Conclusion

In this study, we identified prognostic predictors based on APA events with high accuracy for risk stratification in sarcoma patients and uncovered interesting regulatory networks in sarcoma that could be underlying mechanisms. This study not only provides novel potential prognostic biomarkers but promote precision medicine and provide potential novel research interests for immunotherapy.

The roles and prognostic significance of ABI1-TSV-11 expression in patients with left-sided colorectal cancer

Abnormally expressed and/or phosphorylated Abelson interactor 1 (ABI1) participates in the metastasis and progression of colorectal cancer (CRC). ABI1 presents as at least 12 transcript variants (TSVs) by mRNA alternative splicing, but it is unknown which of them is involved in CRC metastasis and prognosis. Here, we firstly identified ABI1-TSV-11 as a key TSV affecting the metastasis and prognosis of left-sided colorectal cancer (LsCC) and its elevated expression is related to lymph node metastasis and shorter overall survival (OS) in LsCC by analyzing data from The Cancer Genome Atlas and TSVdb. Secondly, ABI1-TSV-11 overexpression promoted LoVo and SW480 cells adhesion and migration in vitro, and accelerated LoVo and SW480 cells lung metastasis in vivo. Finally, mechanism investigations revealed that ABI1-isoform-11 interacted with epidermal growth factor receptor pathway substrate 8 (ESP8) and regulated actin dynamics to affect LoVo and SW480 cells biological behaviors. Taken together, our data demonstrated that ABI1-TSV-11 plays an oncogenic role in LsCC, it is an independent risk factor of prognosis and may be a potential molecular marker and therapeutic target in LsCC.

Systematic Analyses of the Differentially Expressed Alternative Splicing Events in Gastric Cancer and Its Clinical Significance

Accumulation of evidence has indicated a close relationship between alternative splicing (AS) and gastric cancer (GC), whereas systematic analyses of the differentially expressed AS events (DEAS) between GC and normal tissues are lacking. RNA-Seq data and the corresponding clinical information were downloaded from TCGA GC cohort. The percent spliced-in (PSI) value calculated in the GC tissues and normal tissues was employed to quantify the DEAS. Further, survival-associated DEAS and DEAS signatures were identified by univariate and multivariate cox regression analyses. To evaluate the association between DEAS and patients' clinical features, Kaplan-Meier analysis, receiver operator characteristic (ROC) curve, Cox proportional regression and nomograms incorporating the DEAS signatures were performed. DEAS and their splicing networks were finally analyzed by bioinformatics methods. In addition, we use the method of random grouping to divide the samples into the training group and the test group. The final results of the two groups are consistent. After strict filtering, a total of 44,935 AS events were identified, among which 11,141 DEAS were preliminarily screened from 5032 genes. A total of 454 DEAS was associated with OS, and 872 DEAS were associated with DFS. The final prognostic signatures were constructed from the survival-associated DEAS with an area under the receiver operating characteristic (ROC) curve (AUC) greater than 0.6. Only ES in ABI1 was simultaneously associated with OS and DFS. Finally, we identified the splicing correlation network between the prognostic splicing factors (SF) and DEAS in GC. Our study provided a systematic portrait of survival-associated DEAS in GC and uncovered splicing networks that are valuable in deciphering the underlying mechanisms of AS in GC.

CRISPR/CAS9-mediated knockout of Abi1 inhibits p185Bcr-Abl-induced leukemogenesis and signal transduction to ERK and PI3K/Akt pathways

Background

Abl interactor 1 (Abi1) is a downstream target of Abl tyrosine kinases and a component of the WAVE regulatory complex (WRC) that plays an important role in regulating actin cytoskeleton remodeling and membrane receptor signaling. While studies using short hairpin RNA (shRNA) have suggested that Abi1 plays a critical role in Bcr-Abl-induced leukemogenesis, the mechanism involved is not clear.

Methods

In this study, we knocked out Abi1 expression in p185^Bcr-Abl-transformed hematopoietic cells using CRISPR/Cas9-mediated gene editing technology. The effects of Abi1 deficiency on actin cytoskeleton remodeling, the Bcr-Abl signaling, IL-3 independent growth, and SDF-induced chemotaxis in these cells were examined by various in vitro assays. The leukemogenic activity of these cells was evaluated by a syngeneic mouse transplantation model.

Results

We show here that Abi1 deficiency reduced the IL3-independent growth and SDF-1α-mediated chemotaxis in p185^Bcr-Abl-transformed hematopoietic cells and inhibited Bcr-Abl-induced abnormal actin remodeling. Depletion of Abi1 also impaired the Bcr-Abl signaling to the ERK and PI3 kinase/Akt pathways. Remarkably, the p185^Bcr-Abl-transformed cells with Abi1 deficiency lost their ability to develop leukemia in syngeneic mice. Even though these cells developed drug tolerance in vitro after prolonged selection with imatinib as their parental cells, the imatinib-tolerant cells remain incapable of leukemogenesis in vivo.

Conclusions

Together, this study highlights an essential role of Abi1 in Bcr-Abl-induced leukemogenesis and provides a model system for dissecting the Abi1 signaling in Bcr-Abl-positive leukemia.

The Wave complex controls epidermal morphogenesis and proliferation by suppressing Wnt-Sox9 signaling

The Wave complex promotes Arp2/3-mediated actin polymerization. Cohen et al. show that Wave complex activity regulates epidermal shape and growth. Without Wave complex activity, F-actin content is down-regulated and ectopic activity of the Wnt/β-catenin–SOX9 pathway is triggered. This activity induces epidermal hyperproliferation and disrupts tissue architecture.

Development of the skin epidermis requires tight spatiotemporal control over the activity of several signaling pathways; however, the mechanisms that orchestrate these events remain poorly understood. Here, we identify a key role for the Wave complex proteins ABI1 and Wave2 in regulating signals that control epidermal shape and growth. In utero RNAi-mediated silencing of Abi1 or Wasf2 induced cellular hyperproliferation and defects in architecture of the interfollicular epidermis (IFE) and delayed hair follicle growth. Unexpectedly, SOX9, a hair follicle growth regulator, was aberrantly expressed throughout the IFE of the mutant embryos, and its forced overexpression mimicked the Wave complex loss-of-function phenotype. Moreover, Wnt signaling, which regulates SOX9⁺ cell specification, was up-regulated in Wave complex loss-of-function IFE. Importantly, we show that the Wave complex regulates filamentous actin content and that a decrease in actin levels is sufficient to elevate Wnt/β-catenin signaling. Our results identify a novel role for Wave complex– and actin-regulated signaling via Wnt and SOX9 in skin development.

Acute myeloid leukemia with t(10;11)(p11-12;q23.3): Results of Russian Pediatric AML registration study

INTRODUCTION

Translocations involving the KMT2A gene (also known as MLL) are frequently diagnosed in pediatric acute leukemia cases with either lymphoblastic or myeloid origin. KMT2A is translocated to multiple partner genes, including MLLT10/AF10 localizing at chromosomal band 10p12. KMT2A-MLLT10 is one of the common chimeric genes diagnosed in acute leukemia with KMT2A rearrangement (8%), especially in acute myeloid leukemia (AML; 18%). MLLT10 is localized in very close proximity to two other KMT2A partner genes at 10p11-12-NEBL and ABI1, so they could not be distinguished by conventional cytogenetics.

METHODS

In this work, we present a cohort of 28 patients enrolled into Russian Pediatric AML registration study carrying rearrangements between chromosomal regions 11q23.3 and 10p11-12. G-banding, FISH, reverse transcription PCR, and long-distance inverse PCR were used to characterize the KMT2A gene rearrangements in these patients.

RESULTS

We demonstrate that 25 patients harbor the KMT2A-MLLT10 rearrangement, while three patients show the rare KMT2A rearrangements (2× KMT2A-NEBL; 1× KMT2A-ABI1).

CONCLUSIONS

Therefore, the combination of cytogenetic and molecular genetic methods is of high importance in diagnosing cases with t(10;11)(p11-12;q23.3).

MechRNA: prediction of lncRNA mechanisms from RNA-RNA and RNA-protein interactions

Motivation

Long non-coding RNAs (lncRNAs) are defined as transcripts longer than 200 nt that do not get translated into proteins. Often these transcripts are processed (spliced, capped and polyadenylated) and some are known to have important biological functions. However, most lncRNAs have unknown or poorly understood functions. Nevertheless, because of their potential role in cancer, lncRNAs are receiving a lot of attention, and the need for computational tools to predict their possible mechanisms of action is more than ever. Fundamentally, most of the known lncRNA mechanisms involve RNA-RNA and/or RNA-protein interactions. Through accurate predictions of each kind of interaction and integration of these predictions, it is possible to elucidate potential mechanisms for a given lncRNA.

Results

Here, we introduce MechRNA, a pipeline for corroborating RNA-RNA interaction prediction and protein binding prediction for identifying possible lncRNA mechanisms involving specific targets or on a transcriptome-wide scale. The first stage uses a version of IntaRNA2 with added functionality for efficient prediction of RNA-RNA interactions with very long input sequences, allowing for large-scale analysis of lncRNA interactions with little or no loss of optimality. The second stage integrates protein binding information pre-computed by GraphProt, for both the lncRNA and the target. The final stage involves inferring the most likely mechanism for each lncRNA/target pair. This is achieved by generating candidate mechanisms from the predicted interactions, the relative locations of these interactions and correlation data, followed by selection of the most likely mechanistic explanation using a combined P-value. We applied MechRNA on a number of recently identified cancer-related lncRNAs (PCAT1, PCAT29 and ARLnc1) and also on two well-studied lncRNAs (PCA3 and 7SL). This led to the identification of hundreds of high confidence potential targets for each lncRNA and corresponding mechanisms. These predictions include the known competitive mechanism of 7SL with HuR for binding on the tumor suppressor TP53, as well as mechanisms expanding what is known about PCAT1 and ARLn1 and their targets BRCA2 and AR, respectively. For PCAT1-BRCA2, the mechanism involves competitive binding with HuR, which we confirmed using HuR immunoprecipitation assays.

Availability and implementation

MechRNA is available for download at https://bitbucket.org/compbio/mechrna.

Supplementary information

Supplementary data are available at Bioinformatics online.

MiR-181a/b induce the growth, invasion, and metastasis of neuroblastoma cells through targeting ABI1

Neuroblastoma is a pediatric malignancy, and the clinical phenotypes range from localized tumors with excellent outcomes to widely metastatic disease in which long-term survival is approximately 40%, despite intensive therapy. Emerging evidence suggests that aberrant miRNA regulation plays a role in neuroblastoma, but the miRNA functions and mechanisms remain unknown. miR-181 family members were detected in 32 neuroblastoma patients, and the effects of miR-181a/b on cell viability, invasion, and migration were evaluated in vitro and in vivo. A parallel global mRNA expression profile was obtained for neuroblastoma cells overexpressing miR-181a. The potential targets of miR-181a/b were validated. miR-181a/b expression levels were positively associated with MYCN amplification and neuroblastoma aggressiveness. Moreover, ectopic miR-181a/b expression significantly induced the growth and invasion of neuroblastoma cells in vitro and in vivo. Microarray analysis revealed that mRNAs were consistently downregulated after miR-181a overexpression, leading to cell migration. In addition, the expression of ABI1 was suppressed by miR-181a/b, and ABI1 was validated as a direct target of miR-181a/b. We concluded that miR-181a/b were significantly upregulated in aggressive neuroblastoma, which enhanced its tumorigenesis and progression by suppressing the expression of ABI1.

Beclin1 antagonizes LAPTM4B-mediated EGFR overactivation in gastric cancer cells

Beclin1 is an essential autophagy regulator and a haploinsufficient tumor-suppressor. Reduced Berclin1 expression has been associated with many types of human malignancies including gastric cancer. However, the mechanism of how Beclin1 represses tumorigenesis of gastric cancer remains elusive. In recent proteomics study, we found that Beclin1 is associated with Lysosome-associated transmembrane protein 4β (LAPTM4B). LAPTM4B plays an important role in promoting the growth and proliferation of tumor cells, it is overexpressed in a variety of solid tumors and serves as a biomarker for tumor therapy. Further analysis showed that Beclin1 interacts with both the N- and C-termini of LAPTM4B and this interaction is independent of Vps34 complex. We demonstrated that Beclin1 competes with Epidermal growth factor receptor (EGFR) for LAPTM4B binding and Beclin1 can repress the LAPTM4B mediated EGFR activation and gastric cancer cell growth. Taken together, our study proposes a role of Beclin1 in repressing gastric cancer through disrupting the oncogenic promoting function of LAPTM4B.

Oncogenic function and prognostic significance of Abelson interactor 1 in hepatocellular carcinoma

Aberrant expression of Abelson interactor 1 (ABI1) has been reported in multiple cancers. However, its clinical significance and potential biological roles in hepatocellular carcinoma (HCC) have not been fully elucidated. In this study, we found that ABI1 was obviously upregulated in HCC tissues compared with non-tumor tissues. Moreover, high ABI1 expression was significantly correlated with tumor size (P=0.041), tumor number (P<0.001), tumor encapsulation (P<0.001) and BCLC stage (P=0.010). Importantly, Kaplan-Meier survival analysis showed that increased ABI1 expression predicted shorter overall survival time (P<0.001) and a higher tendency of tumor recurrence (P=0.001) in HCC patients. Multivariate Cox regression analysis further confirmed high ABI1 expression was an independent predictor for both overall survival (HR=1.795, P=0.025) and early recurrence (HR=1.893, P=0.012) after surgical resection. Furthermore, in vitro studies indicated that overexpression of ABI1 induced an increase in cell proliferation, migration and invasion of HCC cells, whereas knockdown of ABI1 did the opposite. Xenograft mouse models verified the promoting effects of ABI1 on HCC growth and lung metastasis in vivo. Collectively, our findings indicated that ABI1 contributes to the development and progression of HCC as an oncogene and may serve as a valuable prognostic marker for HCC patients.

Hepatitis C Virus Nonstructural 5A Protein Interacts with Abelson Interactor 1 and Modulates Epidermal Growth Factor-mediated MEK/ERK Signaling Pathway

The propagation of hepatitis C virus (HCV) is highly dependent on host cellular factors. To identify the cellular factors involved in HCV propagation, we have previously performed protein microarray assays using the HCV nonstructural 5A (NS5A) protein as a probe. Of ∼9,000 host proteins immobilized in a microarray, ∼90 cellular proteins were identified as HCV NS5A interacting partners. Of these candidates, we selected Abelson interactor 1 (Abi1) for further characterization. Binding of HCV NS5A to Abi1 was verified by both in vitro pulldown and coimmunoprecipitation assays. HCV NS5A interacted with Abi1 through regions I + II of Abi1 and domain I of NS5A. We further demonstrated that Abi1 colocalized with the HCV NS5A protein in the cytoplasm. We showed that NS5A inhibited epidermal growth factor-mediated ERK and Egr1 activations and this inhibitory activity of NS5A was nullified in Abi1-knockdown cells. Moreover, silencing of Abi1 expression impaired HCV replication, whereas overexpression of Abi1 promoted HCV propagation. Collectively, these data indicate that HCV exploits host Abi1 protein via NS5A to modulate MEK/ERK signaling pathway for its own propagation.

Effect of low doses of estradiol and tamoxifen on breast cancer cell karyotypes

Evidence supports a role of 17&-estradiol (E2) in carcinogenesis and the large majority of breast carcinomas are dependent on estrogen. The anti-estrogen tamoxifen (TAM) is widely used for both treatment and prevention of breast cancer; however, it is also carcinogenic in human uterus and rat liver, highlighting the profound complexity of its actions. The nature of E2- or TAM-induced chromosomal damage has been explored using relatively high concentrations of these agents, and only some numerical aberrations and chromosomal breaks have been analyzed. This study aimed to determine the effects of low doses of E2 and TAM (10(&8 )mol L(&1) and 10(&6 )mol L(&1) respectively) on karyotypes of MCF7, T47D, BT474, and SKBR3 breast cancer cells by comparing the results of conventional karyotyping and multi-FISH painting with cell proliferation. Estrogen receptor (ER)-positive (+) cells showed an increase in cell proliferation after E2 treatment (MCF7, T47D, and BT474) and a decrease after TAM treatment (MCF7 and T47D), whereas in ER& cells (SKBR3), no alterations in cell proliferation were observed, except for a small increase at 96 h. Karyotypes of both ER+ and ER& breast cancer cells increased in complexity after treatments with E2 and TAM leading to specific chromosomal abnormalities, some of which were consistent throughout the treatment duration. This genotoxic effect was higher in HER2+ cells. The ER&/HER2+ SKBR3 cells were found to be sensitive to TAM, exhibiting an increase in chromosomal aberrations. These in vitro results provide insights into the potential role of low doses of E2 and TAM in inducing chromosomal rearrangements in breast cancer cells.

Cytoplasmic Drosha Is Aberrant in Precancerous Lesions of Gastric Carcinoma and Its Loss Predicts Worse Outcome for Gastric Cancer Patients

BACKGROUND

The nuclear localization of Drosha is critical for its function as a microRNA maturation regulator. Dephosphorylation of Drosha at serine 300 and serine 302 disrupts its nuclear localization, and aberrant distribution of Drosha has been detected in some tumors.

AIMS

The purpose of the present study was to assess cytoplasmic/nuclear Drosha expression in gastric cancer carcinogenesis and progression.

METHODS

Drosha expression and its subcellular location was investigated by immunohistochemical staining of a set of tissue microarrays composed of normal adjacent tissues (374), chronic gastritis (137), precancerous lesions (94), and gastric adenocarcinoma (829) samples, and in gastric cancer cell lines with varying differentiation by immunofluorescence and western blot assay.

RESULTS

Gradual loss of cytoplasmic Drosha was accompanied by tumor progression in both gastric cancer tissues and cell lines, and was inversely associated with tumor volume (P = 0.002), tumor grade (P < 0.001), tumor stage (P = 0.018), and distant metastasis (P = 0.026). Aberrant high levels of cytoplasmic Drosha were apparent in intestinal metaplasia and dysplasia tissues. The levels of nuclear Drosha were sharply decreased in chronic gastritis and maintained through precancerous lesions to gastric cancer. High levels of cytoplasmic Drosha predicted longer survival (LR = 7.088, P = 0.008) in gastric cancer patients.

CONCLUSIONS

Our data provide novel insights into gastric cancer that cytoplasmic Drosha potentially plays a role in preventing carcinogenesis and tumor progression, and may be an independent predictor of patient outcome.

G-protein coupled receptor 34 knockdown impairs the proliferation and migration of HGC-27 gastric cancer cells in vitro

Background:

Overexpression of G-protein coupled receptor 34 (GPR34) affects the progression and prognosis of human gastric adenocarcinoma, however, the role of GPR34 in gastric cancer development and progression has not been well-determined. The current study aimed to investigate the effect of GPR34 knockdown on the proliferation, migration, and apoptosis of HGC-27 gastric cancer cells and the underlying mechanisms.

Methods:

The expression of GPR34 in gastric cancer cell line HGC-27 was detected by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. HGC-27 cells were employed to construct the stable GPR34 knockdown cell model in this study. Real-time RT-PCR and Western blotting were applied to validate the effect of short hairpin RNA (ShRNA) on the expression of GPR34 in HGC-27 gastric cells. The proliferation, migration of these cells were examined by Cell Counting Kit-8 and transwell. We also measured expression profile of PI3K/PDK1/AKT and ERK using Western blotting.

Results:

The ShRNA directed against GPR34 effectively inhibited both endogenous mRNA and protein expression levels of GPR34, and significantly down-regulated the expression of PIK3CB (P < 0.01), PIK3CD (P < 0.01), PDK1 (P < 0.01), phosphorylation of PDK1 (P < 0.01), Akt (P < 0.01), and ERK (P < 0.01). Furthermore, GPR34 knockdown resulted in an obvious reduction in HGC-27 cancer cell proliferation and migration activity (P < 0.01).

Conclusions:

GPR34 knockdown impairs the proliferation and migration of HGC-27 gastric cancer cells in vitro and provides a potential implication for therapy of gastric cancer.

Upregulation of Abelson interactor protein 1 predicts tumor progression and poor outcome in epithelial ovarian cancer

Abelson interactor protein 1 (Abi1) is a key regulator of actin reorganization and lamellipodia formation. Because of its role in cell migration, Abi1 has been implicated in tumor progression. In the present study, we investigated the role of Abi1 in epithelial ovarian cancer (EOC) by analyzing its expression and correlation with clinicopathological and survival data. We evaluated the expression of Abi1 in 223 paraffin-embedded EOC specimens by immunohistochemistry and 46 frozen EOC samples by Western blot and real-time reverse transcription polymerase chain reaction analysis. Results showed that Abi1 protein and mRNA expression was significantly higher in EOC tissue compared with noncancerous tumors and normal ovaries (P < .05). Moreover, high level of Abi1 expression was significantly correlated with advanced stage, high grade, elevated Ca-125 level, and suboptimal surgical debulking (P < .05). By Western blot analysis, Abi1 was expressed in highly invasive cells compared with weakly invasive cells (P < .05). Immunofluorescence was performed to demonstrate Abi1 expression in SKOV3 cells. Additionally, upregulation of Abi1 significantly correlated with shorter survival (P < .05). Most importantly, multivariate analysis showed that Abi1 overexpression is an independent prognostic factor, complementary to clinical stage and residual tumor size. In conclusion, our findings suggest that Abi1 acts as a tumor-promoting gene in EOC progression, which may lead to unfavorable prognosis. Abi1 may serve as a potential effective prognostic marker for EOC.

Phosphatidylinositol 3-kinase CB association with preoperative radiotherapy response in rectal adenocarcinoma

AIM: To examine the correlation of phosphatidylinositol 3-kinase (PIK3) CB expression with preoperative radiotherapy response in patients with stage II/III rectal adenocarcinoma.

METHODS: PIK3CB immunoexpression was retrospectively assessed in pretreatment biopsies from 208 patients with clinical stage II/III rectal adenocarcinoma, who underwent radical surgery after 30-Gy/10-fraction preoperative radiotherapy. The relation between PIK3CB expression and tumor regression grade, clinicopathological characteristics, and survival time was statistically analyzed. Western blotting and in vitro clonogenic formation assay were used to detect PIK3CB expression in four colorectal cancer cell lines (HCT116, HT29, LoVo, and LS174T) treated with 6-Gy ionizing radiation. Pharmacological assays were used to evaluate the therapeutic relevance of TGX-221 (a PIK3CB-specific inhibitor) in the four colorectal cancer cell lines.

RESULTS: Immunohistochemical staining indicated that PIK3CB was more abundant in rectal adenocarcinoma tissues with poor response to preoperative radiotherapy. High expression of PIK3CB was closely correlated with tumor height (P < 0.05), ypT stage (P < 0.05), and high-degree tumor regression grade (P < 0.001). High expression of PIK3CB was a potential prognostic factor for local recurrence-free survival (P < 0.05) and metastasis-free survival (P < 0.05). High expression of PIK3CB was also associated with poor therapeutic response and adverse outcomes in rectal adenocarcinoma patients treated with 30-Gy/10-fraction preoperative radiotherapy. In vitro, PIK3CB expression was upregulated in all four colorectal cancer cell lines concurrently treated with 6-Gy ionizing radiation, and the PIK3CB-specific inhibitor TGX-221 effectively inhibited the clonogenic formation of these four colorectal cancer cell lines.

CONCLUSION: PIK3CB is critically involved in response to preoperative radiotherapy and may serve as a novel target for therapeutic intervention.

Crk and ABI1: binary molecular switches that regulate abl tyrosine kinase and signaling to the cytoskeleton

The nonreceptor tyrosine kinases Abl and Arg are among the most well-characterized tyrosine kinases in the human genome. The activation of Abl by N-terminal fusions with Bcr (Bcr-Abl) or Gag (v-Abl) is responsible for chronic myeloid leukemia or Ph+ acute lymphoblastic leukemia and mouse leukemia virus, respectively. In addition, aberrant Abl and Arg activation downstream of several oncogenic growth factor receptors contributes to the development and progression of a variety of human cancers, often associated with poor clinical outcome, drug resistance, and tumor invasion and metastasis. Abl activation can occur by a variety of mechanisms that include domain interactions involving structural remodeling of autoinhibited conformations as well as direct phosphorylation by upstream kinases and phosphatases. Constitutive activation of Abl plays a significant role in regulating the actin cytoskeleton by modulating cell adhesion, motility, and invadopodia. This review addresses the role of Abl and Arg in tumor progression with particular emphasis on the roles of Crk and Abi1 adapter proteins as distinct molecular switches for Abl transactivation. These insights, combined with new insights into the structure of these kinases, provide the rationale to envision that Crk and Abi1 fine-tune Abl regulation to control signaling to the cytoskeleton.

Beclin-1 expression is a significant predictor of survival in patients with lymph node-positive gastric cancer

Background

Beclin 1 is a main actor of autophagy. The expression of Beclin 1 and its prognostic role in gastric cancer is largely unexplored. The purpose of the present study is to investigate the expression of beclin 1 in gastric cancer cells, tissues and its relationship with prognosis.

Methods

The expression of Beclin 1 was detected in 271 specimens of lymph-node positive gastric cancer patients by immunohistochemistry. The correlation of Beclin 1 expression to clinicopathologic features and survival of gastric cancer was studied. Beclin-1 expression in gastric cancer cell lines and clinical specimens is also detected using reverse transcription-PCR and Western blotting.

Results

Beclin 1 is up-regulated at both mRNA and protein levels in six gastric cancer cell lines compared with those in normal gastric mucosa cell line (GES-1). The expression of Beclin-1 in gastric clinical specimens is also higher than those in the adjacent noncancerous tissues. Of the 271 patients, 229 (84.5%) were Beclin 1 high expression tumors by immunohistochemistry. Beclin 1 expression is closely associated with intravascular embolus. Kaplan-Meier analysis showed high beclin 1 expression was associated with longer overall survival. Both univariate analysis and multivariate analysis revealed that Beclin 1 expression were independent prognostic factors in the patients with node-positive gastric cancer.

Conclusions

Our findings strongly suggest that Beclin 1 has a potential role in tumorigenesis of gastric cancer and could be a promising biomarker for predicting the prognosis of patients with lymph node-positive gastric cancer. It might also serve as a novel therapeutic target for gastric cancer treatment.

Disruption of Abi1/Hssh3bp1 expression induces prostatic intraepithelial neoplasia in the conditional Abi1/Hssh3bp1 KO mice

Prostate cancer is one of the leading causes of cancer-related deaths in the United States and a leading diagnosed non-skin cancer in American men. Genetic mutations underlying prostate tumorigenesis include alterations of tumor suppressor genes. We tested the tumor suppressor hypothesis for ABI1/hSSH3BP1 by searching for gene mutations in primary prostate tumors from patients, and by analyzing the consequences of prostate-specific disruption of the mouse Abi1/Hssh3bp1 ortholog. We sequenced the ABI1/hSSH3BP1 gene and identified recurring mutations in 6 out of 35 prostate tumors. Moreover, complementation and anchorage-independent growth, proliferation, cellular adhesion and xenograft assays using the LNCaP cell line, which contains a loss-of-function Abi1 mutation, and a stably expressed wild-type or mutated ABI gene, were consistent with the tumor suppressor hypothesis. To test the hypothesis further, we disrupted the gene in the mouse prostate by breeding the Abi1 floxed strain with the probasin promoter-driven Cre recombinase strain. Histopathological evaluation of mice indicated development of prostatic intraepithelial neoplasia (PIN) in Abi1/Hssh3bp1 knockout mouse as early as the eighth month, but no progression beyond PIN was observed in mice as old as 12 months. Observed decreased levels of E-cadherin, β-catenin and WAVE2 in mouse prostate suggest abnormal cellular adhesion as the mechanism underlying PIN development owing to Abi1 disruption. Analysis of syngeneic cell lines point to the possibility that upregulation of phospho-Akt underlies the enhanced cellular proliferation phenotype of cells lacking Abi1. This study provides proof-of-concept for the hypothesis that Abi1 downregulation has a role in the development of prostate cancer.

Abi1, a critical molecule coordinating actin cytoskeleton reorganization with PI-3 kinase and growth signaling

Coordination of actin cytoskeletal reorganization with growth and proliferation signals is a key cellular process that is not fully understood. PI-3 kinase is one of the central nodes for distributing growth and proliferation signals downstream from growth factor receptors to the nucleus. Although PI-3 kinase function has been associated with actin cytoskeleton remodeling, satisfactory explanations of the mechanisms mediating this regulation have been elusive. Here we propose that interaction of the Abi1 protein with the p85 regulatory subunit of PI-3 kinase represents the link between growth receptor signaling and actin cytoskeleton remodeling. This function of Abi1, which involves WAVE complex, was initially observed in macropinocytosis, and may explain the coincident dysregulation of PI-3 kinase and actin cytoskeleton in cancer.

RACK1 suppresses gastric tumorigenesis by stabilizing the β-catenin destruction complex

BACKGROUND & AIMS

Dysregulation of Wnt signaling has been involved in gastric tumorigenesis by mechanisms that are not fully understood. The receptor for activated protein kinase C (RACK1, GNB2L1) is involved in development of different tumor types, but its expression and function have not been investigated in gastric tumors.

METHODS

We analyzed expression of RACK1 in gastric tumor samples and their matched normal tissues from 116 patients using immunohistochemistry. Effects of knockdown with small interfering RNAs or overexpression of RACK1 in gastric cancer cell lines were evaluated in cell growth and tumor xenograft. RACK1 signaling pathways were investigated in cells and zebrafish embryos using immunoblot, immunoprecipitation, microinjection, and in situ hybridization assays.

RESULTS

Expression of RACK1 was reduced in gastric tumor samples and correlated with depth of tumor infiltration and poor differentiation. Knockdown of RACK1 in gastric cancer cells accelerated their anchorage-independent proliferation in soft agar, whereas overexpression of RACK1 reduced their tumorigenicity in nude mice. RACK1 formed a complex with glycogen synthase kinase Gsk3β and Axin to promote the interaction between Gsk3β and β-catenin and thereby stabilized the β-catenin destruction complex. On stimulation of Wnt3a, RACK1 repressed Wnt signaling by inhibiting recruitment of Axin by Dishevelled 2 (Dvl2). Moreover, there was an inverse correlation between expression of RACK1 and localization of β-catenin to the cytoplasm/nucleus in human gastric tumor samples.

CONCLUSIONS

RACK1 negatively regulates Wnt signaling pathway by stabilizing the β-catenin destruction complex and act as a tumor suppressor in gastric cancer cells.

Endocytosis and signaling: cell logistics shape the eukaryotic cell plan

Our understanding of endocytosis has evolved remarkably in little more than a decade. This is the result not only of advances in our knowledge of its molecular and biological workings, but also of a true paradigm shift in our understanding of what really constitutes endocytosis and of its role in homeostasis. Although endocytosis was initially discovered and studied as a relatively simple process to transport molecules across the plasma membrane, it was subsequently found to be inextricably linked with almost all aspects of cellular signaling. This led to the notion that endocytosis is actually the master organizer of cellular signaling, providing the cell with understandable messages that have been resolved in space and time. In essence, endocytosis provides the communications and supply routes (the logistics) of the cell. Although this may seem revolutionary, it is still likely to be only a small part of the entire story. A wealth of new evidence is uncovering the surprisingly pervasive nature of endocytosis in essentially all aspects of cellular regulation. In addition, many newly discovered functions of endocytic proteins are not immediately interpretable within the classical view of endocytosis. A possible framework, to rationalize all this new knowledge, requires us to "upgrade" our vision of endocytosis. By combining the analysis of biochemical, biological, and evolutionary evidence, we propose herein that endocytosis constitutes one of the major enabling conditions that in the history of life permitted the development of a higher level of organization, leading to the actuation of the eukaryotic cell plan.

Expression of Abl interactor 1 and its prognostic significance in breast cancer: a tissue-array-based investigation

Abl interactor 1 (Abi1) is an adaptor protein involved in cell migration. Previous in vitro work suggested that Abi1 is a regulator of breast cancer proliferation, migration, and invasion. In the present study, we explore the expression of Abi1 and its downstream effector phospho-Akt (p-Akt) in a series of breast cancers and correlate their expression with clinicopathological and survival data. Using tissue microarrays, 988 patients with invasive breast carcinoma were evaluated by immunohistochemistry. Statistical correlation was performed to determine associations between Abi1 and p-Akt expression and standard breast clinicopathological factors. The prognostic value of Abi1 and p-Akt for disease-free (DFS) and overall survival (OS) was also evaluated. Abi1 expression was demonstrated in 33.7% (314/933) of invasive carcinomas, while p-Akt was expressed in 46.7% (441/944). There was a significant association between Abi1 and p-Akt expression (P=0.001). Abi1 expression showed significant positive correlation with older age at diagnosis and the Ki67 index. Most importantly, it was demonstrated to be an independent predictor of both DFS and OS (HR = 1.6 and 1.5, P<0.001, respectively). There was no association between p-Akt expression and survival. To the best of our knowledge, this is the first study evaluating Abi1 expression in a large group of breast cancers. Our analysis demonstrated that tumors expressing high levels of Abi1 are significantly associated with early recurrence and worse survival on multivariate analysis. This suggests that Abi1 expression has potential as a molecular marker to refine outcome prediction in breast cancer patients.