Clinical implications of AGBL2 expression and its inhibitor latexin in breast cancer

AGBL2 promotes renal cell carcinoma cells proliferation and migration via α-tubulin detyrosination

Background

AGBL2's role in tumorigenesis and cancer progression has been reported in several cancer studies, and it is closely associated with α-tubulin detyrosination. The roles of AGBL2 and α-tubulin detyrosination in renal cell carcinoma (RCC) pathogenesis remain unclear and require further investigation.

Methods

In this study, we conducted an analysis of AGBL2 expression differences between renal clear cell carcinoma tissues and normal tissues using data from The Cancer Genome Atlas (TCGA). We performed a comprehensive prognostic analysis of AGBL2 in Kidney Renal Clear Cell Carcinoma (KIRC) using univariate and multivariate Cox regression. Based on the results of the Cox analysis, we constructed a prognostic model to assess its predictive capabilities. Receiver Operating Characteristic (ROC) analysis confirmed the diagnostic value of AGBL2 in renal cancer. We conducted further validation by analyzing cancer tissue samples and renal cancer cell lines, which confirmed the role of AGBL2 in promoting RCC cell proliferation and migration through in vitro experiments. Additionally, we verified the impact of AGBL2's detyrosination on α-tubulin using the tubulin carboxypeptidase (TCP) inhibitor parthenolide. Finally, we performed sequencing analysis on AGBL2 knockdown 786-O cells to investigate the correlation between AGBL2, immune infiltration, and AKT phosphorylation. Moreover, we experimentally demonstrated the enhancing effect of AGBL2 on AKT phosphorylation.

Results

TCGA analysis revealed a significant increase in AGBL2 expression in RCC patients, which was correlated with poorer overall survival (OS), disease-specific survival (DSS), and progression-free intervals (PFI). According to the analysis results, we constructed column-line plots to predict the 1-, 3-, and 5-year survival outcomes in RCC patients. Additionally, the calibration plots assessing the model's performance exhibited favorable agreement with the predicted outcomes. And the ROC curves showed that AGBL2 showed good diagnostic performance in KIRC (AUC = 0.836)). Cell phenotyping assays revealed that AGBL2 knockdown in RCC cells significantly inhibited cell proliferation and migration. Conversely, overexpression of AGBL2 resulted in increased cell proliferation and migration in RCC cells. We observed that AGBL2 is predominantly located in the nucleus and can elevate the detyrosination level of α-tubulin in RCC cells. Moreover, the enhancement of RCC cell proliferation and migration by AGBL2 was partially inhibited after treatment with the TCP inhibitor parthenolide. Analysis of the sequencing data revealed that AGBL2 is associated with a diverse array of biological processes, encompassing signal transduction and immune infiltration. Interestingly, AGBL2 expression exhibited a negative correlation with the majority of immune cell infiltrations. Additionally, AGBL2 was found to enhance the phosphorylation of AKT in RCC cells.

Conclusion

Our study suggests that AGBL2 fosters RCC cell proliferation and migration by enhancing α-tubulin detyrosination. Moreover, elevated AGBL2 expression increases phosphorylation of AKT in RCC cells.

High expression of AGBL2 is a novel prognostic factor of adverse outcome in patients with ovarian carcinoma

The putative oncogenic role of ATP/GTP binding protein like 2 (AGBL2) in catalyzing α-tubulin detyrosination has recently been characterized in cancer. However, the status of AGBL2 expression in ovarian cancer and its potential clinical and prognostic significance remain unclear. In the present study, immunohistochemistry staining investigated the protein expression level of AGBL2 in paraffin-embedded pathological specimens from 30 normal ovaries, 35 ovarian cystadenomas, 38 borderline ovarian tumors and 165 invasive ovarian carcinomas. The association between AGBL2 expression and clinicopathological characteristics of patients was evaluated using the χ² test or Fisher's exact test. The survival status of patients was assessed by receiver-operator curve analysis. The results demonstrated that high expression of AGBL2 was observed in 9% of cystadenomas cases, 21% of borderline tumors cases and 38% of ovarian carcinomas cases; however AGBL2 expression was not high in normal ovarian tissues (P<0.01). Furthermore, the results demonstrated that high expression of AGBL2 was associated with tumor histological grade, advanced pT/pN/pM and cancer stage according to the International Federation of Gynecology and Obstetrics (P<0.05). Following univariate survival analysis of the ovarian carcinoma groups, high expression of AGBL2 was significantly associated with shorter patient survival (P<0.001). In addition, multivariate analysis revealed that AGBL2 could be identified as a potential independent prognostic factor for overall survival in patients with ovarian carcinoma (P=0.004). Furthermore, the results demonstrated that AGBL2 expression was significantly associated with the expression of immunity related GTPase M (IRGM) (P=0.013) and LC3A/B (P=0.004). IRGM expression level was also significantly associated with LC3A/B expression level (P=0.023). These findings demonstrated that AGBL2 expression was high in ovarian carcinomas, which suggested that AGBL2 may participate in the acquisition of an aggressive phenotype and may therefore serve as an independent prognostic molecular marker.

The putative tumour suppressor protein Latexin is secreted by prostate luminal cells and is downregulated in malignancy

Loss of latexin (LXN) expression negatively correlates with the prognosis of several human cancers. Despite association with numerous processes including haematopoietic stem cell (HSC) fate, inflammation and tumour suppression, a clearly defined biological role for LXN is still lacking. Therefore, we sought to understand LXN expression and function in the normal and malignant prostate to assess its potential as a therapeutic target. Our data demonstrate that LXN is highly expressed in normal prostate luminal cells but downregulated in high Gleason grade cancers. LXN protein is both cytosolic and secreted by prostate cells and expression is directly and potently upregulated by all-trans retinoic acid (atRA). Whilst overexpression of LXN in prostate epithelial basal cells did not affect cell fate, LXN overexpression in the luminal cancer line LNCaP reduced plating efficiency. Transcriptome analysis revealed that LXN overexpression had no direct effects on gene expression but had significant indirect effects on important genes involved in both retinoid metabolism and IFN-associated inflammatory responses. These data highlight a potential role for LXN in retinoid signaling and inflammatory pathways. Investigating the effects of LXN on immune cell function in the tumour microenvironment (TME) may reveal how observed intratumoural loss of LXN affects the prognosis of many adenocarcinomas.

Shared genetic architecture between metabolic traits and Alzheimer's disease: a large-scale genome-wide cross-trait analysis

A growing number of studies clearly demonstrate a substantial link between metabolic dysfunction and the risk of Alzheimer's disease (AD), especially glucose-related dysfunction; one hypothesis for this comorbidity is the presence of a common genetic etiology. We conducted a large-scale cross-trait GWAS to investigate the genetic overlap between AD and ten metabolic traits. Among all the metabolic traits, fasting glucose, fasting insulin and HDL were found to be genetically associated with AD. Local genetic covariance analysis found that 19q13 region had strong local genetic correlation between AD and T2D (P = 6.78 × 10- 22), LDL (P = 1.74 × 10- 253) and HDL (P = 7.94 × 10- 18). Cross-trait meta-analysis identified 4 loci that were associated with AD and fasting glucose, 3 loci that were associated with AD and fasting insulin, and 20 loci that were associated with AD and HDL (Pmeta < 1.6 × 10- 8, single trait P < 0.05). Functional analysis revealed that the shared genes are enriched in amyloid metabolic process, lipoprotein remodeling and other related biological pathways; also in pancreas, liver, blood and other tissues. Our work identifies common genetic architectures shared between AD and fasting glucose, fasting insulin and HDL, and sheds light on molecular mechanisms underlying the association between metabolic dysregulation and AD.

Phosphorylation of serine/arginine-rich splicing factor 1 at tyrosine 19 promotes cell proliferation in pediatric acute lymphoblastic leukemia

Serine/arginine‐rich splicing factor 1 (SRSF1) has been linked to various human cancers including pediatric acute lymphoblastic leukemia (ALL). Our previous study has shown that SRSF1 potentially contributes to leukemogenesis; however, its underlying mechanism remains unclear. In this study, leukemic cells were isolated from pediatric ALL bone marrow samples, followed by immunoprecipitation assays and mass spectrometry analysis specific to SRSF1. Subcellular localization of the SRSF1 protein and its mutants were analyzed by immunofluorescence staining. Cell growth, colony formation, cell apoptosis, and the cell cycle were investigated using stable leukemic cell lines generated with lentivirus‐mediated overexpressed WT or mutant plasmids. Cytotoxicity of the Tie2 kinase inhibitor was also evaluated. Our results showed the phosphorylation of SRSF1 at tyrosine 19 (Tyr‐19) was identified in newly diagnosed ALL samples, but not in complete remission or normal control samples. Compared to the SRSF1 WT cells, the missense mutants of the Tyr‐19 phosphorylation affected the subcellular localization of SRSF1. In addition, the Tyr‐19 phosphorylation of SRSF1 also led to increased cell proliferation and enhanced colony‐forming properties by promoting the cell cycle. Remarkably, we further identified the kinase Tie2 as a potential therapeutic target in leukemia cells. In conclusion, we identify for the first time that the phosphorylation state of SRSF1 is linked to different phases in pediatric ALL. The Tyr‐19 phosphorylation of SRSF1 disrupts its subcellular localization and promotes proliferation in leukemia cells by driving cell‐cycle progression. Inhibitors targeting Tie2 kinase that could catalyze Tyr‐19 phosphorylation of SRSF1 offer a promising therapeutic target for treatment of pediatric ALL.

Bone Microenvironment Changes in Latexin Expression Promote Chemoresistance

Although docetaxel is the standard of care for advanced prostate cancer, most patients develop resistance to docetaxel. Therefore, elucidating the mechanism that underlies resistance to docetaxel is critical to enhance therapeutic intervention. Mining cDNA microarray from the PC-3 prostate cancer cell line and its docetaxel-resistant derivative (PC3-TxR) revealed decreased latexin (LXN) expression in the resistant cells. LXN expression was inversely correlated with taxane resistance in a panel of prostate cancer cell lines. LXN knockdown conferred docetaxel resistance to prostate cancer cells in vitro and in vivo, whereas LXN overexpression reduced docetaxel resistance in several prostate cancer cell lines. A mouse model of prostate cancer demonstrated that prostate cancer cells developed resistance to docetaxel in the bone microenvironment, but not the soft tissue microenvironment. This was associated with decreased LXN expression in prostate cancer cells in the bone microenvironment compared with the soft tissue microenvironment. It was identified that bone stromal cells decreased LXN expression through methylation and induced chemoresistance in prostate cancer in vitro These findings reveal that a subset of prostate cancer develops docetaxel resistance through loss of LXN expression associated with methylation and that the bone microenvironment promotes this drug resistance phenotype.Implications: This study suggests that the LXN pathway should be further explored as a viable target for preventing or reversing taxane resistance in prostate cancer. Mol Cancer Res; 15(4); 457-66. ©2017 AACR.

Latexin exhibits tumor-suppressor potential in pancreatic ductal adenocarcinoma

Recent studies suggest that latexin (Lxn) expression is involved in stem cell regulation and that it plays significant roles in tumor cell migration and invasion. The clinicopathological significance of Lxn expression and its possible correlation with CD133 expression in pancreatic ductal adenocarcinoma (PDAC) is currently unknown. In the present study, immunohistochemical analysis was performed to determine Lxn and CD133 expression in 43 PDAC patient samples and in 32 corresponding adjacent non-cancerous samples. The results were analyzed and compared with patient age, gender, tumor site and size, histological grade, clinical stage and overall mean survival time. Lxn expression was clearly decreased in the PDAC tissues compared with that in the adjacent non-cancerous tissues, while CD133 expression was increased. Low Lxn expression in the PDAC tissues was significantly correlated with tumor size (P=0.002), histological grade (P=0.000), metastasis (P=0.007) and clinical stage (P=0.018), but not with age (P=0.451), gender (P=0.395) or tumor site (P=0.697). Kaplan-Meier survival analysis revealed that low Lxn expression was significantly correlated with reduced overall survival time (P=0.000). Furthermore, Lxn expression was found to be inversely correlated with CD133 expression (r=−0.485, P=0.001). Furthermore, CD133-positive MIA PaCa-2 pancreatic tumor cells were sorted by magnetic-activated cell sorting (MACS), and those that overexpressed Lxn exhibited a significantly higher rate of apoptosis and lower proliferative activity. Our findings suggest that Lxn may function as a tumor suppressor that targets CD133-positive pancreatic cancer cells.