AHNAK2 Regulates NF-κB/MMP-9 Signaling to Promote Pancreatic Cancer Progression.

Early metastasis of pancreatic cancer (PaC) is a major cause of its high mortality rate. Previous studies have shown that AHNAK2 is involved in the progression of some tumors and is predicted to be an independent prognostic factor for PaC; however, the specific mechanisms through which AHNAK2 regulates PaC remain unclear. In this study, we examined the role of AHNAK2 in PaC and its potential molecular mechanisms. AHNAK2 mRNA and protein expression in PaC tissues and cells were measured using qRT-PCR and western blot analysis. After AHNAK2 knockdown using small interfering RNA, PaC cells were subjected to CCK-8 scratch, and Transwell assays to assess cell proliferation, migration, and invasion, respectively. Furthermore, the validation of the mechanistic pathway was achieved by western blot analysis. AHNAK2 mRNA and protein levels were up-regulated in PaC and silencing AHNAK2 significantly inhibited the proliferation, migration, and invasion of PaC cells. Mechanistically, AHNAK2 knockdown decreased the expression of phosphorylated p65, phosphorylated IκBα, and matrix metalloproteinase-9 (MMP-9), suggesting that activation of the NF-κB/MMP-9 signaling pathway was inhibited. Importantly, activation of NF-κB reversed the effects of AHNAK2 knockdown. Our findings indicate that AHNAK2 promotes PaC progression through the NF-kB/MMP-9 pathway and provides a theoretical basis for targeting AHNAK2 for the treatment of PaC.

AHNAK2 is a biomarker and a potential therapeutic target of adenocarcinomas.

Adenocarcinoma is the second largest histological type of cervical cancer, second only to cervical squamous cell carcinoma. At present, despite the clinical treatment strategies of cervical adenocarcinoma and cervical squamous cell carcinoma being similar, the outcome and prognosis of cervical adenocarcinoma are significantly poor. Therefore, it is urgent to find specific biomarker and therapeutic target for cervical adenocarcinoma. In this study, we aim to reveal and verify the potential biomarkers and therapeutic targets of cervical adenocarcinoma. Weighted correlation network analysis (WGCNA) reveals the differentially-expressed genes significantly related to the histological characteristics of the two cervical cancer subtypes. We select the genes with the top 20 significance for further investigation. Through microarray and immunohistochemical (IHC) analyses of a variety of tumor tissues, we find that among these 20 genes, AHNAK2 is highly expressed not only in cervical adenocarcinoma, but also in multiple of adenocarcinoma tissues, including esophagus, breast and colon, while not in normal gland tissues. In vitro, AHNAK2 knockdown significantly inhibits cell proliferation and migration of adenocarcinoma cell lines. In vivo, AHNAK2 knockdown significantly inhibits tumor progression and metastasis of various adenocarcinomas. RNA-sequencing and bioinformatics analyses suggest that the inhibitory effect of AHNAK2 knockdown on tumor progression is achieved by regulating DNA replication and upregulating Bim expression. Together, we demonstrate that AHNAK2 is a biomarker and a potential therapeutic target for adenocarcinomas.

Linkage analysis and whole exome sequencing reveals AHNAK2 as a novel genetic cause for autosomal recessive CMT in a Malaysian family.

Charcot-Marie-Tooth (CMT) disease is a form of inherited peripheral neuropathy that affects motor and sensory neurons. To identify the causative gene in a consanguineous family with autosomal recessive CMT (AR-CMT), we employed a combination of linkage analysis and whole exome sequencing. After excluding known AR-CMT genes, genome-wide linkage analysis mapped the disease locus to a 7.48-Mb interval on chromosome 14q32.11-q32.33, flanked by the markers rs2124843 and rs4983409. Whole exome sequencing identified two non-synonymous variants (p.T40P and p.H915Y) in the AHNAK2 gene that segregated with the disease in the family. Pathogenic predictions indicated that p.T40P is the likely causative allele. Analysis of AHNAK2 expression in the AR-CMT patient fibroblasts showed significantly reduced mRNA and protein levels. AHNAK2 binds directly to periaxin which is encoded by the PRX gene, and PRX mutations are associated with another form of AR-CMT (CMT4F). The altered expression of mutant AHNAK2 may disrupt the AHNAK2-PRX interaction in which one of its known functions is to regulate myelination.

AHNAK2 Participates in the Stress-Induced Nonclassical FGF1 Secretion Pathway.

FGF1 is a nonclassically released growth factor that regulates carcinogenesis, angiogenesis, and inflammation. In vitro and in vivo, FGF1 export is stimulated by cell stress. Upon stress, FGF1 is transported to the plasma membrane where it localizes prior to transmembrane translocation. To determine which proteins participate in the submembrane localization of FGF1 and its export, we used immunoprecipitation mass spectrometry to identify novel proteins that associate with FGF1 during heat shock. The heat shock-dependent association of FGF1 with the large protein AHNAK2 was observed. Heat shock induced the translocation of FGF1 and AHNAK2 to the cytoskeletal fraction. In heat-shocked cells, FGF1 and the C-terminal fragment of AHNAK2 colocalized with F-actin in the vicinity of the cell membrane. Depletion of AHNAK2 resulted in a drastic decrease of stress-induced FGF1 export but did not affect spontaneous FGF2 export and FGF1 release induced by the inhibition of Notch signaling. Thus, AHNAK2 is an important element of the FGF1 nonclassical export pathway.

Identification of gemcitabine resistance-related AHNAK2 gene associated with prognosis and immune infiltration in pancreatic cancer.

Purpose: Gemcitabine is a basic chemotherapy drug for pancreatic cancer (PC), but resistance is common and causes tumor recurrence and metastasis. Therefore, it is significant to explore gemcitabine resistance-related molecules for individualized treatment and prognosis assessment of PC. Methods: In this study, transcriptome sequencing and TCGA database analysis were performed, and a differentiated gene AHNAK2 was screened. MEXPRESS database, tissue microarray analysis, and CIBERSORT and TIMER databases were used to correlate AHNAK2 expression with clinicopathological features and prognosis and immune infiltration of PC. Enrichment analysis was used to investigate the significant biological processes associated with AHNAK2. Results: AHNAK2 was highly expressed in gemcitabine-resistant cells. High expression of AHNAK2 increased the risk of poor overall survival (OS) and progression-free survival (PFS) in PC. Clinicopathologic analysis revealed that AHNAK2 correlated with KRAS, TP53 mutations, histologic type, short OS, N stage, and elevated CA199 levels in PC. Knockdown of AHNAK2 inhibited the ability of cell proliferation and colony formation and enhanced the toxic effect of gemcitabine in PC. Meanwhile, the knockdown of AHNAK2 expression enhanced cell-ECM adhesion, inhibited cell-cell adhesion, and downregulated the KRAS/p53 signaling pathway in PC. Furthermore, AHNAK2 was correlated with immune infiltration, especially B cells and macrophages. Conclusions: Our study unveils for the first time the pivotal role of AHNAK2 in PC, particularly its association with gemcitabine resistance, clinical prognosis, and immune infiltration. AHNAK2 not only drives the proliferation and drug resistance of PC cells by potentially activating the KRAS/p53 pathway but also significantly impacts cell-cell and cell- ECM adhesion. Additionally, AHNAK2 plays a crucial role in modulating the tumor immune microenvironment. These insights underscore AHNAK2's unique potential as a novel therapeutic target for overcoming gemcitabine resistance, offering new perspectives for PC treatment strategies.

AHNAK2 Promotes the Progression of Pancreatic Ductal Adenocarcinoma by Maintaining the Stability of c-MET.

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is extremely malignant and rapidly progresses. The overall response rate of PDAC to current treatment methods is still unsatisfactory. Thus, identifying novel targets and clarifying the underlying mechanisms associated with PDAC progression may potentially offer additional treatment strategies. AHNAK2 is aberrantly expressed in a variety of tumors and exerts pro-tumorigenic effects. However, the biological role of AHNAK2 in PDAC remains poorly understood. Methods: The expression of AHNAK2 in PDAC and paired non-tumor tissues was detected by immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR). Lentivirus knockdown was performed to investigate the impact of AHNAK2 on the biological function of pancreatic cancer cells. The subcutaneous cell-derived xenograft (CDX) model and the KPC spontaneous mouse model with AHNAK2 silencing were used to observe the effects of AHNAK2 on tumor growth and prognosis. The expression of c-MET at protein level in response to HGF treatment was assessed using western blot. Results: Our results demonstrated that AHNAK2 was highly expressed in PDAC clinical samples and associated with poor prognosis. Knockdown of AHNAK2 significantly inhibited the proliferation, migration, and invasion of pancreatic cancer cells. AHNAK2 knockdown or knockout resulted in tumor growth suppression and prolonged survival in mice with PDAC. In addition, AHNAK2 and c-MET expression levels showed a significant positive correlation at the post-transcriptional level. Mechanistically, AHNAK2 promoted tumor progression by preventing c-MET degradation and persistently activating the HGF/c-MET signaling pathway. Conclusion: Overall, our study revealed that AHNAK2 plays an important role in PDAC progression by modulating the c-MET signaling pathway, and targeting AHNAK2 may be an effective therapeutic strategy for PDAC.

AHNAKs roles in physiology and malignant tumors.

The AHNAK family currently consists of two members, namely AHNAK and AHNAK2, both of which have a molecular weight exceeding 600 kDa. Homologous sequences account for approximately 90% of their composition, indicating a certain degree of similarity in terms of molecular structure and biological functions. AHNAK family members are involved in the regulation of various biological functions, such as calcium channel modulation and membrane repair. Furthermore, with advancements in biological and bioinformatics technologies, research on the relationship between the AHNAK family and tumors has rapidly increased in recent years, and its regulatory role in tumor progression has gradually been discovered. This article briefly describes the physiological functions of the AHNAK family, and reviews and analyzes the expression and molecular regulatory mechanisms of the AHNAK family in malignant tumors using Pubmed and TCGA databases. In summary, AHNAK participates in various physiological and pathological processes in the human body. In multiple types of cancers, abnormal expression of AHNAK and AHNAK2 is associated with prognosis, and they play a key regulatory role in tumor progression by activating signaling pathways such as ERK, MAPK, Wnt, and MEK, as well as promoting epithelial-mesenchymal transition.

Downregulation of AHNAK2 inhibits cell cycle of lung adenocarcinoma cells by interacting with RUVBL1.

BACKGROUND: Lung adenocarcinoma (LUAD) is the leading cause of death among cancer diseases. The tumorigenic functions of AHNAK2 in LUAD have attracted more attention in recent years, while there are few studies which have reported its high molecular weight. METHODS: The mRNA-seq data of AHNAK2 and corresponding clinical data from UCSC Xena and GEO was analyzed. LUAD cell lines were transfected with sh-NC and sh-AHNAK2, and cell proliferation, migration and invasion were then detected by in vitro experiments. We performed RNA sequencing and mass spectrometry analysis to explore the downstream mechanism and interacting proteins of AHNAK2. Finally, western blot, cell cycle analysis and CO-IP were used to confirm our assumptions regarding previous experiments. RESULTS: Our study revealed that AHNAK2 expression was significantly higher in tumors than in normal lung tissues and higher AHNAK2 expression led to a poor prognosis, especially in patients with advanced tumors. AHNAK2 suppression via shRNA reduced the LUAD cell lines proliferation, migration and invasion and induced significant changes in DNA replication, NF-kappa B signaling pathway and cell cycle. AHNAK2 knockdown also caused G1/S phase cell cycle arrest, which could be attributed to the interaction of AHNAK2 and RUVBL1. In addition, the results from gene set enrichment analysis (GSEA) and RNA sequencing suggested that AHNAK2 probably plays a part in the mitotic cell cycle. CONCLUSION: AHNAK2 promotes proliferation, migration and invasion in LUAD and regulates the cell cycle via the interaction with RUVBL1. More studies of AHNAK2 are still needed to reveal its upstream mechanism.

Deleterious AHNAK2 Mutation as a Novel Biomarker for Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer.

Immune checkpoint inhibitors (ICIs) have exhibited promising efficacy in non-small cell lung cancer (NSCLC), but the response occurs in only a minority of patients. In clinic, biomarkers such as TMB (tumor mutation burden) and PD-L1 (programmed cell death 1 ligand 1) still have their limitations in predicting the prognosis of ICI treatment. Hence, reliable predictive markers for ICIs are urgently needed. A public immunotherapy dataset with clinical information and mutational data of 75 NSCLC patients was obtained from cBioPortal as the discovery cohort, and another immunotherapy dataset of 249 patients across multiple cancer types was collected as the validation. Integrated bioinformatics analysis was performed to explore the potential mechanism, and immunohistochemistry studies were used to verify it. AHNAK nucleoprotein 2 (AHNAK2) was reported to have pro-tumor growth effects across multiple cancers, while its role in tumor immunity was unclear. We found that approximately 11% of the NSCLC patients harbored AHNAK2 mutations, which were associated with promising outcomes to ICI treatments (ORR, p = 0.013). We further found that AHNAK2 deleterious mutation (del-AHNAK2 mut) possessed better predictive function in NSCLC than non-deleterious AHNAK2 mutation (PFS, OS, log-rank p < 0.05), potentially associated with stronger tumor immunogenicity and an activated immune microenvironment. This work identified del-AHNAK2 mut as a novel biomarker to predict favorable ICI response in NSCLC.

The Obscure Potential of AHNAK2.

AHNAK2 is a protein discovered in 2004, with a strong association with oncogenesis in various epithelial cancers. It has a large 616 kDa tripartite structure and is thought to take part in the formation of large multi-protein complexes. High expression is found in clear cell renal carcinoma, pancreatic ductal adenocarcinoma, uveal melanoma, and lung adenocarcinoma, with a relation to poor prognosis. Little work has been done in exploring the function and relation AHNAK2 has with cancer, with early studies showing promising potential as a future biomarker and therapeutic target.

Exome sequencing in a child with neurodevelopmental disorder and epilepsy: Variant analysis of the AHNAK2 gene.

BACKGROUND: The AHNAK2 gene encodes a large nucleoprotein expressed in several tissues, including brain, squamous epithelia, smooth muscle, and neuropil. Its role in calcium signaling has been suggested and to date, clear evidence about its involvement in the pathogenesis of clinical disorders is still lacking. METHODS: Here, we report a female 24-year-old patient diagnosed with a cardio-facio-cutaneous-like phenotype (CFC-like), characterized by epilepsy, psychomotor development delay, atopic dermatitis, congenital heart disease, hypotonia, and facial dysmorphism, who is compound heterozygote for two missense mutations in the AHNAK2 gene detected by exome sequencing. RESULTS: This patient had no detectable variant in any of the genes known to be associated with the cardio-facio-cutaneous syndrome. Moreover, the mode of inheritance does not appear to be autosomal dominant, as it is in typical CFC syndrome. We have performed in silico assessment of mutation severity separately for each missense mutation, but this analysis excludes a severe effect on protein function. Protein structure predictions indicate the mutations are located in flexible regions possibly involved in molecular interactions. CONCLUSION: We discuss an alternative interpretation on the potential involvement of the two missense mutations in the AHNAK2 gene on the expression of CFC-like phenotype in this patient based on inter-allelic complementation.

AHNAK2 promotes the progression of differentiated thyroid cancer through PI3K/AKT signaling pathway.

AIMS: AHNAK2 may be used as a candidate marker for TC diagnosis and treatment. BACKGROUND: Thyroid cancer [TC] is the most frequent malignancy in endocrine carcinoma, and the incidence has been increasing for decades. OBJECTIVE: To understand the molecular mechanism of DTC, we performed next-generation sequencing [NGS] on 79 paired DTC tissues and normal thyroid tissues. The RNA-sequencing [RNA-seq] data analysis results indicated that AHNAK nucleoprotein 2 [AHNAK2] was significantly upregulated in the thyroid cancer patient's tissue. METHOD: We also analyzed AHNAK2 mRNA levels of DTC tissues and normal tissues from The Cancer Genome Atlas [TCGA]. The association between the expression level of AHNAK2 and clinicopathological features was evaluated in the TCGA cohort. Furthermore, AHNAK2 gene expression was analyzed by quantitative real-time polymerase chain reaction [qRT-PCR] in 40 paired DTC tissues and adjacent normal thyroid tissues. The receiver operating characteristic [ROC] curve was performed to evaluate the diagnostic value of AHNAK2. For cell experiments in vitro, AHNAK2 was knocked down using small interfering RNA [siRNA], and the biological function of AHNAK2 in TC cell lines was investigated. The expression of AHNAK2 was significantly upregulated in both the TCGA cohort and the local cohort. RESULT: The analysis results of the TCGA cohort indicated that the upregulation of AHNAK2 was associated with tumor size [P<0.001], lymph node metastasis [P<0.001], and disease stage [P<0.001]. The area under the curve [AUC] [TCGA: P<0.0001; local validated cohort: P<0.0001.] in the ROC curve revealed that AHNAK2 might be considered a diagnostic biomarker for TC. The knockdown of AHNAK2 reduced TC cell proliferation, colony formation, migration, invasion, cell cycle, and induced cell apoptosis. CONCLUSION: Furthermore, the protein levels of phospho-PI3 Kinase p85 and phospho-AKT were down-regulated in the transfected TC cell. Our study results indicate that AHNAK2 may promote metastasis and proliferation of thyroid cancer through PI3K/AKT signaling pathway. Thus, AHNAK2 may be used as a candidate marker for TC diagnosis and treatment.

Calcium sparks enhance the tissue fluidity within epithelial layers and promote apical extrusion of transformed cells.

In vertebrates, newly emerging transformed cells are often apically extruded from epithelial layers through cell competition with surrounding normal epithelial cells. However, the underlying molecular mechanism remains elusive. Here, using phospho-SILAC screening, we show that phosphorylation of AHNAK2 is elevated in normal cells neighboring RasV12 cells soon after the induction of RasV12 expression, which is mediated by calcium-dependent protein kinase C. In addition, transient upsurges of intracellular calcium, which we call calcium sparks, frequently occur in normal cells neighboring RasV12 cells, which are mediated by mechanosensitive calcium channel TRPC1 upon membrane stretching. Calcium sparks then enhance cell movements of both normal and RasV12 cells through phosphorylation of AHNAK2 and promote apical extrusion. Moreover, comparable calcium sparks positively regulate apical extrusion of RasV12-transformed cells in zebrafish larvae as well. Hence, calcium sparks play a crucial role in the elimination of transformed cells at the early phase of cell competition.

Prognostic Impact of AHNAK2 Expression in Patients Treated with Radical Cystectomy.

Data regarding expression levels of AHNAK2 in bladder cancer (BCa) have been very scarce. We retrospectively reviewed clinical data including clinicopathological features in 120 patients who underwent radical cystectomy (RC) for BCa. The expression levels of AHNAK2 in the specimens obtained by RC were classified as low expression (LE) or high expression (HE) by immunohistochemical staining. Statistical analyses were performed to compare associations between the two AHNAK2 expression patterns and the prognoses in terms of recurrence-free survival (RFS) and cancer-specific survival (CSS). A Kaplan-Meier analysis showed that patients with HE had a significantly worse RFS and CSS than those with LE (hazard ratio [HR]: 1.78, 95% confidence interval [CI]: 1.02-2.98, p = 0.027 and HR: 1.91, 95% CI: 1.08-3.38, p = 0.023, respectively). In a multivariate analysis, independent risk factors for worse RFS and CSS were shown as HE (HR: 1.96, 95% CI: 1.08-3.53, p = 0.026 and HR: 2.22, 95% CI: 1.14-4.31, p = 0.019, respectively) and lymph node metastasis (HR: 2.04, 95% CI: 1.09-3.84, p = 0.026 and HR: 1.19, 95% CI: 1.25-4.97, p = 0.009, respectively). The present study showed that AHNAK2 acts as a novel prognostic biomarker in patients with RC for BCa.

Correlation between prognostic indicator AHNAK2 and immune infiltrates in lung adenocarcinoma.

BACKGROUND: Lung adenocarcinoma (LUAD) is among the most aggressive malignant tumors in humans. Although AHNAK nucleoprotein 2 (AHNAK2) is considered a new oncogene, the function of the AHNAK2 in LUAD remains unknown. METHODS: Oncomine, Tumor Immune Estimation Resource (TIMER), and Human Protein Atlas databases were used to investigate AHNAK2 expression in LUAD. Gene Expression Profiling Interactive Analysis and Kaplan-Meier plotter databases were employed to elucidate the relationship between AHNAK2 and survival time. Data of The Cancer Genome Atlas were downloaded to analyze the correlation between AHNAK2 and clinicopathological parameters. We then immunohistochemically stained tissue chips to further confirm the correlation and conducted Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction network analyses to explore the possible functional mechanism of AHNAK2. Finally, we investigated the relationship between AHNAK2 and tumor infiltrating immune cells (TIICs). RESULTS: AHNAK2 gene was significantly overexpressed in LUAD tumor tissues and an independent prognostic indicator of LUAD patients. The expression of AHNAK2 was related to disease stage, differentiation, tumor size and lymph node metastasis. We found AHNAK2 expression was mainly positively correlated with cell adhesion-related pathways and negatively correlated with oxidative phosphorylation and amino acid metabolism. AHNAK2 expression was also negatively correlated with activated B cell, activated CD8 + T cell, and immature B cell infiltrates and positively correlated with central memory CD4 + T cell, tumor-associated macrophage, M1 macrophage, and M2 macrophage infiltrates. CONCLUSION: Our findings provide strong evidence of AHNAK2 expression as a prognostic indicator related to TIICs in LUAD.

AHNAK2 promotes thyroid carcinoma progression by activating the NF-κB pathway.

Thyroid carcinoma metastasis is the main reason for treatment failure; therefore, understanding the regulatory mechanisms of thyroid carcinoma metastasis is critical to treat patients with thyroid carcinoma. The present study aimed to investigate the role of AHNAK Nucleoprotein 2 (AHNAK2) in thyroid carcinoma metastasis. AHNAK2 was found to be upregulated in thyroid carcinoma tissues, especially in metastatic thyroid carcinoma tissues. Patients with high AHNAK2 expression had poor prognosis. AHNAK2 knockdown inhibited thyroid carcinoma migration, invasion, and metastasis. Mechanistic analysis showed that AHNAK2 knockdown reduced thyroid carcinoma progression by inhibiting nuclear factor kappa B (NF-κB) pathway activity. The results identified a novel target to treat metastatic thyroid carcinoma.

AHNAK2 is a novel prognostic marker and correlates with immune infiltration in papillary thyroid cancer: Evidence from integrated analysis.

Papillary thyroid cancer (PTC) is the most prevalent endocrine tumor, and its incidence is still increasing. The mechanisms of PTC dedifferentiation and malignant progression remain unclear. In this study, we identified AHNAK2 as a key gene in PTC by differential expression analysis among four GEO datasets and validated its overexpression profile by data from the Oncomine, TCGA, and HPA databases and IHC staining analysis. AHNAK2 upregulation significantly correlated with advanced grades, stages, and lymph node events. Survival analysis suggested that AHNAK2 overexpression was coupled with poor overall survival. The immune infiltration analysis by TIMER and CIBERSORT indicated that AHNAK2 expression tightly correlated with the infiltration of diverse immune cell types, especially T cell subtypes. In addition, AHNAK2 is correlated with the expression of other conventional key genes of TC, such as PIK3CA, MAPK1, CTNNB1, and SLC5A5. AHNAK2 may be a novel prognostic marker for PTC.

Application of Label-Free Proteomics for Quantitative Analysis of Urothelial Carcinoma and Cystitis Tissue.

A label-free approach based on a highly reproducible and stable workflow allows for quantitative proteome analysis . Due to advantages compared to labeling methods, the label-free approach has the potential to measure unlimited samples from clinical specimen monitoring and comparing thousands of proteins. The presented label-free workflow includes a new sample preparation technique depending on automatic annotation and tissue isolation via FTIR-guided laser microdissection, in-solution digestion, LC-MS/MS analyses, data evaluation by means of Proteome Discoverer and Progenesis software, and verification of differential proteins. We successfully applied this workflow in a proteomics study analyzing human cystitis and high-grade urothelial carcinoma tissue regarding the identification of a diagnostic tissue biomarker. The differential analysis of only 1 mm2 of isolated tissue cells led to 74 significantly differentially abundant proteins.

Down-Regulation of AHNAK2 Inhibits Cell Proliferation, Migration and Invasion Through Inactivating the MAPK Pathway in Lung Adenocarcinoma.

AHNAK nucleoprotein 2 (AHNAK2) has been emerged as a crucial protein for neuroblast differentiation and cell migration, thereby involving in the development of various cancers. However, the specific molecular mechanism of AHNAK2 in lung adenocarcinoma is inconclusive. By accessing to the Oncomine dataset and GEPIA website, a higher expression level of AHNAK2 was observed in lung adenocarcinoma tissue samples. Overall survival (OS) curve plotted by Kaplan-Meier method showed that up-regulation of AHNAK2 was related with poor prognosis of lung adenocarcinoma patients. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis and western blot were conducted to examine the expression level of genes in lung adenocarcinoma cells. Through functional in vitro experiments, cell proliferation, migration and invasion were all suppressed after AHNAK2 knockdown using Cell counting kit-8 (CCK-8) assay, wound-healing and transwell analysis. Reduction of AHNAK2 decreased the apoptosis rate using flow cytometry analysis. Moreover, the key markers of MAPK pathway, p-MEK, p-ERK and p-P90RSK were decreased due to the transfection of si-AHNAK2 in A549 cells. U0126, a MEK inhibitor, showed the similar effects on MAPK-related protein levels with si-AHNAK2. To sum up, AHNAK2 is significantly increased in lung adenocarcinoma and plays a carcinogenic role by activating the MAPK signaling pathway, providing a novel insight and raising possibility for lung adenocarcinoma treatment.

AHNAK2 Promotes Migration, Invasion, and Epithelial-Mesenchymal Transition in Lung Adenocarcinoma Cells via the TGF-ß/Smad3 Pathway.

PURPOSE: Lung adenocarcinoma is one of the common causes of cancer-related deaths worldwide. AHNAKs are giant proteins, which are correlated with cell structure and migration, cardiac calcium channel signaling, and other processes. Current studies identified AHNAK2 as a novel oncogene in some cancers; however, studies on its function in lung cancers are limited. MATERIALS AND METHODS: The expression of AHNAK2 was analyzed in normal lung tissues, lung adenocarcinoma tissues, and paracancerous tissues using the Oncomine database. It was further verified in relative cell lines by real-time quantitative polymerase chain reaction and Western blotting (WB). Adenocarcinoma cell lines were transfected with si-NC and si-AHNAK2 by lipofectamine 3000 and treated with or without TGF-ß1, and cell migration and invasion were detected by wound-healing and transwell assays. The expression of epithelial-mesenchymal transition (EMT) markers was detected by WB, as well as that of phosphorylated-Smad3 (p-Smad3) and Smad3 levels. After Smad3 phosphorylation inhibitor was added to the adenocarcinoma cell lines, migration and invasion were detected by wound-healing and transwell assays, and the expression of EMT markers was detected by WB when the cells were transfected with si-NC and si-AHNAK2 and treated with or without TGF-ß1. RESULTS: We found higher expression of AHNAK2 in lung adenocarcinoma tissues through the Oncomine database and further verified its high expression in relative cell lines. When the cells were stimulated with TGF-ß1, knockdown of AHNAK2 suppressed cell migration, invasion, and EMT, and inhibited TGF-ß-induced Smad3 signaling. When p-Smad3 was inhibited, knockdown of AHNAK2 had no effect on the two cell lines investigated when treated with or without TGF-ß1. CONCLUSION: AHNAK2 acts as an oncogenic protein and promotes migration, invasion, and EMT in lung adenocarcinoma cells via the TGF-ß/Smad3 pathway. Thus, it may be a novel target for lung adenocarcinoma therapy.