The forkhead transcription factor FOXO1 mediates cisplatin resistance in gastric cancer cells by activating phosphoinositide 3-kinase/Akt pathway

Cancer Mutations Converge on a Collection of Protein Assemblies to Predict Resistance to Replication Stress

Rapid proliferation is a hallmark of cancer associated with sensitivity to therapeutics that cause DNA replication stress (RS). Many tumors exhibit drug resistance, however, via molecular pathways that are incompletely understood. Here, we develop an ensemble of predictive models that elucidate how cancer mutations impact the response to common RS-inducing (RSi) agents. The models implement recent advances in deep learning to facilitate multidrug prediction and mechanistic interpretation. Initial studies in tumor cells identify 41 molecular assemblies that integrate alterations in hundreds of genes for accurate drug response prediction. These cover roles in transcription, repair, cell-cycle checkpoints, and growth signaling, of which 30 are shown by loss-of-function genetic screens to regulate drug sensitivity or replication restart. The model translates to cisplatin-treated cervical cancer patients, highlighting an RTK-JAK-STAT assembly governing resistance. This study defines a compendium of mechanisms by which mutations affect therapeutic responses, with implications for precision medicine.

SIGNIFICANCE

Zhao and colleagues use recent advances in machine learning to study the effects of tumor mutations on the response to common therapeutics that cause RS. The resulting predictive models integrate numerous genetic alterations distributed across a constellation of molecular assemblies, facilitating a quantitative and interpretable assessment of drug response. This article is featured in Selected Articles from This Issue, p. 384.

M6A demethylase ALKBH5 regulates FOXO1 mRNA stability and chemoresistance in triple-negative breast cancer

Resistance to chemotherapy is the main reason for treatment failure and poor prognosis in patients with triple-negative breast cancer (TNBC). Although the association of RNA N6-methyladenosine (m6A) modifications with therapy resistance is noticed, its role in the development of therapeutic resistance in TNBC is not well documented. This study aimed to investigate the potential mechanisms underlying reactive oxygen species (ROS) regulation in doxorubicin (DOX)-resistant TNBC. Here, we found that DOX-resistant TNBC cells displayed low ROS levels because of increased expression of superoxide dismutase (SOD2), thus maintaining cancer stem cells (CSCs) characteristics and DOX resistance. FOXO1 is a master regulator that reduces cellular ROS in DOX-resistant TNBC cells, and knockdown of FOXO1 significantly increased ROS levels by inhibiting SOD2 expression. Moreover, the m6A demethylase ALKBH5 promoted m6A demethylation of FOXO1 mRNA and increased FOXO1 mRNA stability in DOX-resistant TNBC cells. The analysis of clinical samples revealed that the increased expression levels of ALKBH5, FOXO1, and SOD2 were significantly positively correlated with chemoresistance and poor prognosis in patients with TNBC. To our knowledge, this is the first study to highlight that ALKBH5-mediated FOXO1 mRNA demethylation contributes to CSCs characteristics and DOX resistance in TNBC cells. Furthermore, pharmacological targeting of FOXO1 profoundly restored the response of DOX-resistant TNBC cells, both in vitro and in vivo. In conclusion, we demonstrated a critical function of ALKBH5-mediated m6A demethylation of FOXO1 mRNA in restoring redox balance, which in turn promoting CSCs characteristics and DOX resistance in TNBC, and suggested that targeting the ALKBH5/FOXO1 axis has therapeutic potential for patients with TNBC refractory to chemotherapy.

Mutations in the DNA polymerase binding pathway affect the immune microenvironment of patients with small-cell lung cancer and enhance the efficacy of platinum-based chemotherapy

Background

Small-cell lung cancer (SCLC) is characterized by its high malignancy and is associated with a poor prognosis. In the early stages of the disease, platinum-based chemotherapy is the recommended first-line treatment and has demonstrated efficacy. However, SCLC is prone to recurrence and is generally resistant to chemotherapy in its later stages.

Methods

Here, we collected samples from SCLC patients who received platinum-based chemotherapy, performed genomic and transcriptomic analyses, and validated our results with publicly available data.

Results

SCLC patients with DNA polymerase binding pathway mutations had an improved prognosis after platinum chemotherapy compared with patients without such mutations. Patients in the mutant (MT) group had higher infiltration of T cells, B cells, and M1 macrophages compared with patients without DNA polymerase binding pathway mutations.

Conclusions

DNA polymerase binding pathway mutations can be used as prognostic markers for platinum-based chemotherapy in SCLC.

Forkhead box proteins as the critical regulators of cisplatin response in tumor cells

Cisplatin (CDDP) is one of the most common chemotherapy drugs used in a wide range of cancer patients; however, there is a high rate of CDDP resistance among cancer patients. Considering the side effects of cisplatin in normal tissues, it is necessary to predict the CDDP response in cancer patients. Therefore, identifying the molecular mechanisms involved in CDDP resistance can help to introduce the prognostic markers. Several molecular mechanisms such as apoptosis inhibition, drug efflux, drug detoxification, and increased DNA repair are involved in CDDP resistance. Regarding the key role of transcription factors in regulation of many cellular processes related to drug resistance, in the present review, we discussed the role of Forkhead box (FOX) protein family in CDDP response. It has been reported that FOX proteins mainly promote CDDP resistance through the regulation of DNA repair, autophagy, epithelial-mesenchymal transition (EMT), and signaling pathways. Therefore, FOX proteins can be introduced as the prognostic markers to predict CDDP response in cancer patients. In addition, considering that oncogenic role of FOX proteins, the CDDP treatment along with FOX inhibition can be used as a therapeutic strategy in cancer patients.

Depletion of circPDSS1 inhibits ITGA11 production to confer cisplatin sensitivity through miR-515-5p in gastric cancer

Chemoresistance limits cisplatin (DDP)-mediated treatment for gastric cancer (GC). Circular RNA (circRNA) acts an important role in chemoresistance. However, the underlying mechanism of circPDSS1 regulating DDP sensitivity in GC remains unclear. The expression patterns of circPDSS1, miR-515-5p and integrin subunit alpha 11 (ITGA11) were analyzed by qRT-PCR. Protein expression was checked by Western blotting analysis. Cell viability was investigated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation was evaluated by colony formation assay and 5-ethynyl-2'-deoxyuridine (EdU) assay. The analysis of cell apoptosis, migration and invasion was performed by flow cytometry analysis and transwell assays. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to identify the associations among circPDSS1, miR-515-5p and ITGA11. In vivo assay was implemented using a xenograft mouse model assay. CircPDSS1 and ITGA11 expression were significantly upregulated, whereas miR-515-5p was downregulated in DDP-resistant GC tissues and cells in comparison with controls. CircPDSS1 depletion reduced DDP resistance, cell proliferation, migration and invasion but induced cell apoptosis in DDP-resistant GC cells. CircPDSS1 directly bound to miR-515-5p. CircPDSS1-mediated actions were dependent on the regulation of miR-515-5p. Besides, miR-515-5p was associated with ITGA11, and circPDSS1 regulated ITGA11 expression by binding to miR-515-5p. Overexpression of miR-515-5p improved DDP sensitivity owing to the downregulation of ITGA11. Further, circPDSS1 mediated DDP sensitivity by regulating miR-515-5p and ITGA11 in vivo. CircPDSS1 conferred DDP resistance through the miR-515-5p/ITGA11 axis in GC cells.

PLAGL2 promotes Snail expression and gastric cancer progression via UCA1/miR-145-5p/YTHDF1 axis

OBJECTIVES

Although great progress has made in gastric cancer (GC) in the past years, the overall 5-year survival rate remains to be low for advanced GC patients. A recent study showed that PLAGL2 was increased in GC and enhanced the proliferation and metastasis of GC. Nevertheless, the underlying mechanism still needs to be investigated.

METHODS

Gene and protein expressions were assessed using RT-qPCR and western blot. The migration, proliferation and invasion of GC cells were examined using scratch assay, CCK-8 assay and Transwell assay, respectively. ChIP-PCR, dual-luciferase assay, RIP-qPCR and CoiP were utilized to confirm the interaction among PLAGL2, UCA1, miR-145-5p and YTHDF1 as well as METTL3, YTHDF1 and eEF-2. A mouse xenograft model was used utilized to further confirm the regulatory network.

RESULTS

PLAGL2 bound to the upstream promoter of UCA1, which regulated YTHDF1 by sponging miR-145-5p. METTL3 can mediate the m6A modification level of Snail. YTHDF1 recognized m6A-modified Snail by interacting with eEF-2 and thus promoted Snail expression, which eventually induced epithelial-mesenchymal transition (EMT) in GC cells and metastasis of GC.

CONCLUSIONS

Overall, our study demonstrates that PLAGL2 enhances Snail expression and GC progression via the UCA1/miR-145-5p/YTHDF1 axis, suggesting that PLAGL2 may become a therapeutic target for GC treatment.

SIRT1 mediated gastric cancer progression under glucose deprivation through the FoxO1-Rab7-autophagy axis

Purpose

Silent mating type information regulator 2 homolog 1 (SIRT1) and autophagy have a two-way action (promoting cell death or survival) on the progression and treatment of gastric cancer (GC) under different conditions or environments. This study aimed to investigate the effects and underlying mechanism of SIRT1 on autophagy and the malignant biological behavior of GC cells under conditions of glucose deprivation (GD).

Materials and methods

Human immortalized gastric mucosal cell GES-1 and GC cell lines SGC-7901, BGC-823, MKN-45 and MKN-28 were utilized. A sugar-free or low-sugar (glucose concentration, 2.5 mmol/L) DMEM medium was used to simulate GD. Additionally, CCK8, colony formation, scratches, transwell, siRNA interference, mRFP-GFP-LC3 adenovirus infection, flow cytometry and western blot assays were performed to investigate the role of SIRT1 in autophagy and malignant biological behaviors (proliferation, migration, invasion, apoptosis and cell cycle) of GC under GD and the underlying mechanism.

Results

SGC-7901 cells had the longest tolerance time to GD culture conditions, which had the highest expression of SIRT1 protein and the level of basal autophagy. With the extension of GD time, the autophagy activity in SGC-7901 cells also increased. Under GD conditions, we found a close relationship between SIRT1, FoxO1 and Rab7 in SGC-7901 cells. SIRT1 regulated the activity of FoxO1 and upregulated the expression of Rab7 through deacetylation, which ultimately affected autophagy in GC cells. In addition, changing the expression of FoxO1 provided feedback on the expression of SIRT1 in the cell. Reducing SIRT1, FoxO1 or Rab7 expression significantly inhibited the autophagy levels of GC cells under GD conditions, decreased the tolerance of GC cells to GD, enhanced the inhibition of GD in GC cell proliferation, migration and invasion and increased apoptosis induced by GD.

Conclusion

The SIRT1-FoxO1-Rab7 pathway is crucial for the autophagy and malignant biological behaviors of GC cells under GD conditions, which could be a new target for the treatment of GC.

METTL3 Mediates Epithelial-Mesenchymal Transition by Modulating FOXO1 mRNA N6 -Methyladenosine-Dependent YTHDF2 Binding: A Novel Mechanism of Radiation-Induced Lung Injury

The biological roles of epithelial-mesenchymal transition (EMT) in the pathogenesis of radiation-induced lung injury (RILI) have been widely demonstrated, but the mechanisms involved have been incompletely elucidated. N⁶ -methyladenosine (m⁶ A) modification, the most abundant reversible methylation modification in eukaryotic mRNAs, plays vital roles in multiple biological processes. Whether and how m⁶ A modification participates in ionizing radiation (IR)-induced EMT and RILI remain unclear. Here, significantly increased m⁶ A levels upon IR-induced EMT are detected both in vivo and in vitro. Furthermore, upregulated methyltransferase-like 3 (METTL3) expression and downregulated α-ketoglutarate-dependent dioxygenase AlkB homolog 5 (ALKBH5) expression are detected. In addition, blocking METTL3-mediated m⁶ A modification suppresses IR-induced EMT both in vivo and in vitro. Mechanistically, forkhead box O1 (FOXO1) is identified as a key target of METTL3 by a methylated RNA immunoprecipitation (MeRIP) assay. FOXO1 expression is downregulated by METTL3-mediated mRNA m⁶ A modification in a YTH-domain family 2 (YTHDF2)-dependent manner, which subsequently activates the AKT and ERK signaling pathways. Overall, the present study shows that IR-responsive METTL3 is involved in IR-induced EMT, probably by activating the AKT and ERK signaling pathways via YTHDF2-dependent FOXO1 m⁶ A modification, which may be a novel mechanism involved in the occurrence and development of RILI.

The FOXO family of transcription factors: key molecular players in gastric cancer

Gastric cancer (GC) is the fifth most frequently diagnosed cancer worldwide and the third leading cause of cancer-related death with an oncological origin. Despite its decline in incidence and mortality in recent years, GC remains a global public problem that seriously threatens patients' health and lives. The forkhead box O proteins (FOXOs) are a family of evolutionarily conserved transcription factors (TFs) with crucial roles in cell fate decisions. In mammals, the FOXO family consists of four members FOXO1, 3a, 4, and 6. FOXOs play crucial roles in a variety of biological processes, such as development, metabolism, and stem cell maintenance, by regulating the expression of their target genes in space and time. An accumulating amount of evidence has shown that the dysregulation of FOXOs is involved in GC progression by affecting multiple cellular processes, including proliferation, apoptosis, invasion, metastasis, cell cycle progression, carcinogenesis, and resistance to chemotherapeutic drugs. In this review, we systematically summarize the recent findings on the regulatory mechanisms of FOXO family expression and activity and elucidate its roles in GC progression. Moreover, we also highlight the clinical implications of FOXOs in GC treatment.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Diverse roles of FOXO family members in gastric cancer

Gastric cancer (GC) is the fifth most diagnosed cancer and the third leading cause of cancer-related death worldwide. Although progress has been made in diagnosis, surgical resection, systemic chemotherapy, and immunotherapy, patients with GC still have a poor prognosis. The overall 5-year survival rate in patients with advanced GC is less than 5%. The FOXO subfamily, of the forkhead box family of transcription factors, consists of four members, FOXO1, FOXO3, FOXO4, and FOXO6. This subfamily plays an important role in many cellular processes, such as cell cycle, cell growth, apoptosis, autophagy, stress resistance, protection from aggregate toxicity, DNA repair, tumor suppression, and metabolism, in both normal tissue and malignant tumors. Various studies support a role for FOXOs as tumor suppressors based on their ability to inhibit angiogenesis and metastasis, and promote apoptosis, yet several other studies have shown that FOXOs might also promote tumor progression in certain circumstances. To elucidate the diverse roles of FOXOs in GC, this article systematically reviews the cellular functions of FOXOs in GC to determine potential therapeutic targets and treatment strategies for patients with GC.

FOXO1 and FOXO3a sensitize non-small-cell lung cancer cells to cisplatin-induced apoptosis independent of Bim

Low sensitivity to chemotherapy has been a major challenge in the treatment of non-small-cell lung cancer (NSCLC). It is of great clinical significance to discover its mechanisms to improve cell sensitivity to chemotherapeutic drugs. The forkhead box subfamily O (FOXO) transcriptional factors are downstream factors of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway and are reported to play pro-apoptotic roles in a variety of cells including NSCLC cells. But their roles and mechanisms in mediating cell response to chemotherapy remain to be discovered. We proposed that FOXO1 and FOXO3a may increase the sensitivity of NSCLC cells to cisplatin. Moreover, we presumed that LY294002, an inhibitor of the PI3K/AKT pathway, may enhance the cytotoxic effects of cisplatin through upregulating FOXO1 and FOXO3a. In the present study, we found that cisplatin initially increased the expressions and nuclear accumulation of FOXO1 and FOXO3a in NSCLC. Knockdown of FOXO1 and FOXO3a significantly decreased the cell sensitivity to cisplatin in vitro and in vivo. Moreover, inhibition of FOXO1 and FOXO3a attenuated cisplatin-induced cell apoptosis independent of Bim, a pro-apoptotic protein downstream of the FOXOs. Moreover, LY294002 synergistically increased the cytotoxic effects of cisplatin. Mechanistically, LY294002 increased the expressions and nuclear accumulation of FOXO1 and FOXO3a. Knockdown of FOXO1 and FOXO3a abrogated the enhancing effect of LY294002 on cisplatin. Taken together, our results suggested that FOXO1 and FOXO3a sensitize NSCLC cells to cisplatin and mediate the enhancing effects of LY294002 on cisplatin.

LncRNA ANCR Promotes Invasion and Migration of Gastric Cancer by Regulating FoxO1 Expression to Inhibit Macrophage M1 Polarization

BACKGROUND

Long non-coding RNAs (LncRNAs) are closely related to the occurrence of cancer, but its mechanism in gastric cancer (GC) is still largely unclear.

AIMS

This study aimed to reveal the underlying mechanism of LncRNA ANCR in GC.

METHODS

The expression of LncRNA ANCR was detected by qRT-PCR. ELISA was used to identify THP-1 cells into macrophage M1 type polarization. After macrophages overexpressing LncRNA ANCR were co-cultured with GC cell HGC-27, the invasion and metastasis of GC were analyzed by Transwell assay. The targeted regulation of FoxO1 by LncRNA ANCR was analyzed by RNA pull-down, RNA immunoprecipitation (RIP), and Western blot. The BALB/c nude mouse model of GC was established to analyze the effect of LncRNA ANCR on tumor growth.

RESULTS

LncRNA ANCR was highly expressed in GC. The overexpression of LncRNA ANCR in macrophages reduced the concentrations of M1 macrophage polarized marker molecules IL-1β and IL-6 in the supernatant of cells, and inhibited the polarization of macrophages to M1, while the knockdown of LncRNA ANCR produced the opposite effect. The co-culture of macrophages overexpressing LncRNA ANCR with GC cells promoted the invasion and migration of cells. LncRNA ANCR targeted FoxO1 and inhibited the expression of FoxO1 in THP-1 cells by promoting FoxO1 ubiquitination degradation. In addition, the overexpression of LncRNA ANCR promoted tumor growth in a BALB/c nude mouse model of GC, while the knockdown of LncRNA ANCR produced the opposite effect.

CONCLUSIONS

Based on these results, the overexpression of LncRNA ANCR promoted the invasion and metastasis of GC cells via down-regulating FoxO1 to inhibit macrophage polarization to M1.

FUT4siRNA augments the chemosensitivity of non-small cell lung cancer to cisplatin through activation of FOXO1-induced apoptosis

Background

Increased fucosylation is associated with the chemoresistance phenotype. Meanwhile, fucosyltransferase IV (FUT4) amounts are frequently elevated in lung cancer and may be related to increased chemoresistance.

Methods

In the present work, FUT4’s role in cisplatin-induced apoptosis was assessed in A549 and H1975 cells, respectively. To clarify whether the FUT4 gene attenuates chemosensitivity in tumor cells, we constructed FUT4siRNA and evaluated its effects on cisplatin-induced apoptosis and cell growth inhibition. Cell viability, apoptosis, migration and invasion assay were conducted to investigate cisplatin sensitivity. The activation of EGFR/AKT/FOXO1 signaling were measured by western blot. The translocation of FOXO1 was assessed by IFC using Laser Scanning Confocal Microscope.

Results

We found that FUT4 knockdown dose-dependently increased cisplatin-associated cytotoxicity. Furthermore, FUT4 silencing induced apoptosis and inhibited proliferation in A549 and H1975 cells by suppressing Akt and FOXO1 phosphorylation induced by cisplatin administration, which resulted in nuclear translocation of FOXO1.

Conclusion

These results suggested FUT4 might control chemoresistance to cisplatin in lung cancer by suppressing FOXO1-induced apoptosis.

miR193b Promotes Apoptosis of Gastric Cancer Cells via Directly Mediating the Akt Pathway

Gastric cancer (GC) is one of the most common and fatal malignancies worldwide. MicroRNAs (miRNAs) play a critical role in tumor initiation, proliferation, and metastasis of gastric cancer. miR193b has been identified as a tumor suppressor in a variety of tumor types; however, its role in gastric cancer is yet to be determined. Here, we found a significant downregulation of miR193b expression in both human gastric cancer tissues (p < 0.05) and human gastric cancer cell lines (p < 0.01). Furthermore, the expression level of miR193b correlated with the tumor type, tumor size, and clinical stage (p < 0.05). In vitro, miR193b overexpression inhibited cell survival and induced apoptosis in GC cell lines, indicating that miR193b plays a role in the development of gastric cancer. KRAS was verified as the target of miR193b, and KRAS overexpression attenuated miR193b-induced apoptosis (p < 0.05). Moreover, we found that the Akt pathway negatively regulated miR193b, also affecting apoptosis. Further analyses indicated that PIK3CA mutation and KRAS amplification are two mutually exclusive pathways (p < 0.01), and we hypothesize that both two pathways could result in the carcinogenic overactivation of KRAS. Thus, our results suggest that the Akt-miR193b-KRAS axis may act as a mechanism affecting apoptosis in gastric cancer cells.

EGFR Blockade Reverses Cisplatin Resistance in Human Epithelial Ovarian Cancer Cells

Background:

EOC is one of the most lethal gynecological malignancy worldwide. Although the majority of EOC patients achieve clinical remission after induction therapy, over 80% relapse and succumb to the chemoresistant disease. Previous investigations have demonstrated the association of EGFR with resistance to cytotoxic chemotherapies, hormone therapy, and radiotherapy in the cancers. These studies have highlighted the role of EGFR as an attractive therapeutic target in cisplatin-resistant EOC cells.

Methods:

The human ovarian cell lines (SKOV3 and OVCAR3) were cultured according to ATCC recommendations. The MTT assay was used to determine the chemosensitivity of the cell lines in exposure to cisplatin and erlotinib. The qRT-PCR was applied to analyze the mRNA expression of the desired genes.

Results:

Erlotinib in combination with cisplatin reduced the cell proliferation in the chemoresistant EOC cells in comparison to monotherapy of the drugs (p < 0.05). Moreover, erlotinib/cisplatin combination synergistically decreased the expression of anti-apoptotic and also increased pro-apoptotic genes expression (p < 0.05). Cisplatin alone could increase the expression of MDR genes. The data suggested that EGFR and cisplatin drive chemoresistance in the EOC cells through MEKK signal transduction as well as through EGFR/MEKK pathways in the cells, respectively.

Conclusion:

Our findings propose that EGFR is an attractive therapeutic target in chemoresistant EOC to be exploited in translational oncology, and erlotinib/cisplatin combination treatment is a potential anti-cancer approach to overcome chemoresistance and inhibit the proliferation of the EOC cells.

FKBP10 functioned as a cancer-promoting factor mediates cell proliferation, invasion, and migration via regulating PI3K signaling pathway in stomach adenocarcinoma

As documented, the expression, biological roles, and prognostic significance of FKBP10 in stomach adenocarcinoma (STAD) have not been investigated till now. This drives us to detect the biological roles and clinical significance of FKBP10 in STAD. The expression level of FKBP10 was measured based on the data obtained from the TCGA, ONCOMINE, and GEPIA databases, and STAD cell lines. Through in vitro experiments, cell behaviors were investigated to evaluate the effects of FKBP10 on STAD. Moreover, the PI3K-AKT signaling pathway was measured. Relying on the data of TCGA, ONCOMINE, and GEPIA databases, and cancer cell lines, FKBP10 was up-regulated in STAD when compared with normals. The patients with low expression of FKBP10 had higher survival rate than those with high FKBP10 expression. After knockdown of FKBP10 in AGS cells, cell vitality, colony formation ability, and the migratory and invasive potential were inhibited. Western blotting analysis exhibited that knockdown of FKBP10 significantly reduced the expression level of p-AKT, and p-PI3K, but it did not influence the total expression level of AKT, and PI3K. FKBP10 might serve as a crucial player in gastric cancer, and targeting FKBP10 might provide clinical utility in gastric cancer in future.

LncRNA ADAMTS9-AS2 inhibits cell proliferation and decreases chemoresistance in clear cell renal cell carcinoma via the miR-27a-3p/FOXO1 axis

Accumulating evidence reveals the principal role of long noncoding RNAs in the progression of clear cell renal cell carcinoma (ccRCC). However, little is known about the underlying mechanism of ADAM metallopeptidase with thrombospondin type 1 motif, 9 antisense RNA 2 (ADAMTS9-AS2) in ccRCC. Here, bioinformatics analyses verified ADAMTS9-AS2 is a long noncoding RNA and its high expression was associated with better prognosis of ccRCC. ADAMTS9-AS2 was clearly downregulated in ccRCC clinical samples and cell lines. Clinical data showed low-expressed ADAMTS9-AS2 was correlated with worse overall survival in ccRCC patients. Next, miR-27a-3p was identified as an inhibitory target of ADAMTS9-AS2 by dual-luciferase reporter and RNA immunoprecipitation assays. Both overexpressed ADAMTS9-AS2 and underexpressed miR-27a-3p in ccRCC cell lines led to the inhibition of cell proliferation and the reduction of chemoresistance. Additionally, Forkhead Box Protein O1 (FOXO1) was confirmed as the inhibitory target of miR-27a-3p. Induced by ADAMTS9-AS2 overexpression, cell proliferation and chemoresistance exhibited an obvious reduction, FOXO1 expression showed an evident increase, but all were reversed after miR-27a-3p was simultaneously overexpressed. Collectively, these results suggest ADAMTS9-AS2 inhibits the progression and impairs the chemoresistance of ccRCC via miR-27a-3p-mediated regulation of FOXO1 and may serve as a prognostic biomarker and therapeutic target for ccRCC.

Forkhead box protein O1 (FOXO1) and paired box gene 3 (PAX3) overexpression is associated with poor prognosis in patients with cervical cancer

PURPOSE

Forkhead box protein O1 (FOXO1) and paired box gene 3 (PAX3) have been reported to play an imported role in human cancers, but their role in cervical cancer has not yet been clarified. In this study, we evaluated the functional role of FOXO1 in cervical cancer cells and investigated the expression and clinical significance of FOXO1 and PAX3 in cervical lesions.

METHODS

In vitro assessment of cell function by cell viability, migration, and invasion assays were performed on FOXO1-knockdown cervical cancer cells. Immunohistochemical (IHC) staining analyses of FOXO1 and PAX3 were performed with a tissue microarray (TMA). The clinical significance was evaluated by comparing the data with various clinicopathologic characteristics, including survival of patients with cervical cancer.

RESULTS

In vitro results revealed that knockdown of FOXO1 is associated with decreased cell viability (p < 0.001), migration (p < 0.001), and invasion (p < 0.05), supporting the oncogenic role of FOXO1 in cervical cancer. FOXO1 and PAX3 expression was significantly higher in CIN (both p < 0.001) and cancer tissue (both p < 0.001) than in normal tissue. Multivariate analysis indicated that FOXO1 expression (hazard ratio 4.01 [95% CI 1.22-13.10], p = 0.021) and an advanced FIGO stage (hazard ratio 3.89 [95% CI 1.35-11.19], p = 0.012) were independent prognostic factors for overall survival.

CONCLUSIONS

This study reveals increased FOXO1 and PAX3 expression in cervical cancers and indicates an oncogenic role of FOXO1 in cervical cancer cells that correlates with poor patient survival.

Alantolactone induces gastric cancer BGC-823 cell apoptosis by regulating reactive oxygen species generation and the AKT signaling pathway

Alantolactone (ALT), a natural sesquiterpene lactone, has been suggested to exert anti-cancer activities in various cancer cell lines. However, the effects and mechanisms of action of ALT in human gastric cancer remains to be elucidated. In the present study, the effects of ALT on BGC-823 cells were examined and the underlying molecular mechanisms associated with these effects were investigated. Cell viability was detected by using an MTT assay. Cell cycle, cell apoptosis and the level of reactive oxygen species (ROS) were assessed by flow cytometry, and the expression levels of proteins of interest were analyzed by western blot assay. The results demonstrated that ALT triggered apoptosis and induced G0/G1 phase arrest in a dose-dependent manner. Furthermore, the expression level of the anti-apoptosis protein Bcl-2 was downregulated, and expression of the pro-apoptosis proteins Bax and cleaved PARP were significantly upregulated. The cell cycle-associated proteins cyclin-dependent kinase inhibitor 1 and cyclin-dependent kinase inhibitor 1B were also increased, while cyclin D1 was deceased. In addition, ALT induced apoptosis via the inhibition of RAC-alpha serine/threonine-protein kinase (AKT) signaling and ROS generation, which was effectively inhibited by the ROS scavenger, N-acetyl cysteine. Therefore, the results from the present study indicated that the ROS-mediated inhibition of the AKT signaling pathway serves an important role in ALT-induced apoptosis in BGC-823 cells. In conclusion, the results demonstrated that ALT exerted significant anti-cancer effects against gastric cancer cells in vitro.

MiR-3188 Inhibits Non-small Cell Lung Cancer Cell Proliferation Through FOXO1-Mediated mTOR-p-PI3K/AKT-c-JUN Signaling Pathway

This study investigated the role of miR-3188 on the proliferation of non-small cell lung cancer cells and its relationship to FOXO1-modulated feedback loop. Two non-small cell lung cancer (NSCLC) cell lines A549 and H1299 were used. RNA silencing was achieved by lentiviral transfection. Cell proliferation was assessed by immunohistochemical staining of Ki67 and PCNA, Edu incorporation, and colony formation assay. Western blotting was used to examine expression of FOXO1, mTOR, p-mTOR, CCND1, p21, c-JUN, AKT, pAKT, PI3K, p-PI3K, and p27 proteins. It was found that miR-3188 reduced cell proliferation in NSCLC cells. Molecular analyses indicated that the effect of mammalian target of rapamycin (mTOR) was directly mediated by miR-3188, leading to p-PI3K/p-AKT/c-JUN inactivation. The inhibition of this signaling pathway further caused cell-cycle suppression. Moreover, FOXO1 was found to be involved in regulating the interaction of miR-3188 and mTOR through p-PI3K/p-AKT/c-JUN signaling pathway. Taken together, our study demonstrated that miR-3188 interacts with mTOR and FOXO1 to inhibit NSCLC cell proliferation through a mTOR-p-PI3K/AKT-c-JUN signaling pathway. Therefore, miR-3188 might be a potential target for the treatment of NSCLC.

The Dominant Role of Forkhead Box Proteins in Cancer

Forkhead box (FOX) proteins are multifaceted transcription factors that are significantly implicated in cancer, with various critical roles in biological processes. Herein, we provide an overview of several key members of the FOXA, FOXC, FOXM1, FOXO and FOXP subfamilies. Important pathophysiological processes of FOX transcription factors at multiple levels in a context-dependent manner are discussed. We also specifically summarize some major aspects of FOX transcription factors in association with cancer research such as drug resistance, tumor growth, genomic alterations or drivers of initiation. Finally, we suggest that targeting FOX proteins may be a potential therapeutic strategy to combat cancer.

FOXO1: Another avenue for treating digestive malignancy?

Digestive malignancies are the leading cause of mortality among all neoplasms, contributing to estimated 3 million deaths in 2012 worldwide. The mortality rate hassurpassed lung cancer and prostate cancer in recent years. The transcription factor Forkhead Box O1 (FOXO1) is a key member of Forkhead Box family, regulating diverse cellular functions during tumor initiation, progression and metastasis. In this review, we focus on recent studies investigating the antineoplastic role of FOXO1 in digestive malignancy. This review aims to serve as a guide for further research and implicate FOXO1 as a potent therapeutic target in digestive malignancy.

Bioinformatic Analysis of GLI1 and Related Signaling Pathways in Chemosensitivity of Gastric Cancer

Background

This study assessed the prognostic value of GLI1 in gastric cancer and analyzed the possible GLI1-related signaling network in chemosensitivity.

Material/Methods

Bioinformatic data mining was performed by using data in the TCGA-Stomach Cancer (TCGA-STAD) and the Kaplan-Meier plotter. GLI1 co-expressed genes in TCGA-STAD were subjected to KEGG pathway analysis. The genes enriched in the KEGG pathways were further subjected to Protein-Protein Interaction (PPI) analysis.

Results

In TCGA-STAD, high GLI1 gene/exon expression was associated with significantly worse survival (p=0.016 and 0.0023 respectively). In the Kaplan-Meier plotter, high GLI1 expression was associated with unfavorable overall survival (OS) (HR: 1.68, 95%CI: 1.42–2, p<0.0001) and first progression-free survival (FPS) (HR: 1.72, 95%CI: 1.4–2.11, p<0.0001). In TCGA-STAD, 600 GLI1 co-expressed genes were identified (absolute Pearson’s r ≥0.5). The most significant pathways were pathways in cancer (p=230.0E-12) and the Hedgehog signaling pathway (p=6.9E-9). PI3K-AKT pathway (p=17.0E-9) has the largest proportion of gene enrichment. Some GLI1 co-expressed genes in the PI3K-AKT pathway are central nodes in the PPI network and also play important roles in chemosensitivity of gastric cancer. Nevertheless, the mechanisms underlying their co-expression are still largely unexplored.

Conclusions

High GLI1 expression is associated with unfavorable OS and FPS in patients with gastric cancer. As a member of the Hedgehog signaling pathway, GLI1 co-expressed genes are also largely enriched in PI3K/AKT pathway in gastric cancer, which is closely related to chemoresistance. The underlying mechanisms are still largely unexplored and need further study.

HOXB7 overexpression promotes cell proliferation and correlates with poor prognosis in gastric cancer patients by inducing expression of both AKT and MARKs

Increased expression of HOXB7 has been reported to correlate with the progression in many cancers. However, the specific mechanism by which it promotes the evolution of gastric cancer (GC) is poorly understood.In this study, we sought to investigate the role of HOXB7 in GC by assessing HOXB7 expression in patient tissue and its correlation to clinical characteristics. We found that GC tissues showed increased expression of HOXB7 and that the HOXB7 expression was significantly associated with Lauren classification, invasion depth, lymphatic metastasis and poor prognosis, and could serve as an independent prognostic factor. To further investigate the role of HOXB7 in GC, we generated stable GC cell lines and both over-expressed and knocked down HOXB7 expression. Over-expression of HOXB7 in GC cell lines enhanced cell proliferation, colony formation, migration and invasion ability, whereas the opposite trends were observed upon reduction of HOXB7 expression by knockdown. These findings were further supported by our in vivo studies which show that HOXB7 expression can affect the GC cells' subcutaneous growth and lung metastases. A Phospho-MAPK Array Kit was used to explore the possible mechanism of HOXB7-induced cell proliferation and invasion. We found that the AKT signaling pathway and the two members of the MAPK pathway, were involved in those promoting effects. In conclusion, our results showed that increased expression of HOXB7 might play an important role in promoting GC proliferation, migration and invasion by inducing both AKT and MAPK pathways, thus resulting in progression of, and poor prognosis in GC patients.

MicroRNA expression profiling in exosomes derived from gastric cancer stem-like cells

Cancer stem-like cells (CSCs) have been identified as the initial cell in formation of cancer. Quiescent CSCs can "hide out" from traditional cancer therapy which may produce an initial response but are often unsuccessful in curing patients. Thus, levels of CSC in patients may be used as an indicator to measure the chance of recurrence of cancer after therapy. The goals of our work are to develop specific exosomal miRNA clusters for gastric CSCs that can potentially predict which patients are at high risk for developing gastric cancer (GC) in order to diagnose GC at an early stage. Here, upon sorting gastric CSCs, we initially isolated and characterized exosomes secreted by both gastric CSCs and their differentiated cells (DCs). By deep sequencing of each exosomal miRNA library, 11 typical differentially expressed miRNAs were identified as signature miRNAs for CSC. Gene target prediction, GO annotation and KEGG pathway enrichment analysis showed possible functions associated with these signature miRNAs. Hence, upon research of exosomal miRNAs that would influence behavior of tumor cells and their microenvironment, this study shows that a specific miRNA signature is present in CSCs, and implies that a potential miRNA biomarker reflecting the stage of gastric cancer progression and metastasis could be developed in the foreseeable future.

Shp2 confers cisplatin resistance in small cell lung cancer via an AKT-mediated increase in CA916798

The tyrosine phosphatase Shp2 is associated with tumorigenesis in small cell lung cancer (SCLC). However, the relationship between Shp2 and resistance to chemotherapy remains unclear. Here, we show that Shp2 plays an important role in inducing resistance to cisplatin-based chemotherapy via the SHP2-AKT-CA916798 pathway. In an SCLC cell line, overexpression of Shp2 induced cisplatin resistance and the increased expression of AKT, pAKT, pmTOR, and CA916798. Conversely, depletion of Shp2 in a cisplatin-resistant cell line via RNA interference increased cisplatin sensitivity and decreased AKT, pAKT, pmTOR, and CA916798 expression levels. Activation of AKT stimulated CA916798 expression and altered the level of Shp2. A mouse xenograft model verified the results obtained from the in vitro experiments. In addition, we collected and analyzed clinical SCLC specimens and found that Shp2 levels correlated with CA916798 expression in tumor tissues. Importantly, higher levels of Shp2 or CA916798 were associated with a poorer prognosis in SCLC patients who received chemotherapy. Together, our findings indicate that Shp2 induces cisplatin resistance in SCLC patients via the SHP2-AKT-CA916798 pathway. Therefore, Shp2 and CA916798 may be promising biomarkers for predicting resistance to chemotherapy and may function as targets for enhancing treatments.

α-Actinin-4 promotes metastasis in gastric cancer

Metastasis increases the mortality rate of gastric cancer, which is the third leading cause of cancer-associated deaths worldwide. This study aims to identify the genes promoting metastasis of gastric cancer (GC). A human cell motility PCR array was used to analyze a pair of tumor and non-tumor tissue samples from a patient with stage IV GC (T3N3M1). Expression of the dysregulated genes was then evaluated in GC tissue samples (n=10) and cell lines (n=6) via qPCR. Expression of α-actinin-4 (ACTN4) was validated in a larger sample size (n=47) by qPCR, western blot and immunohistochemistry. Knockdown of ACTN4 with specific siRNAs was performed in GC cells, and adhesion assays, transwell invasion assays and migration assays were used to evaluate the function of these cells. Expression of potential targets of ACTN4 were then evaluated by qPCR. Thirty upregulated genes (greater than twofold) were revealed by the PCR array. We focused on ACTN4 because it was upregulated in 6 out of 10 pairs of tissue samples and 5 out of 6 GC cell lines. Further study indicated that ACTN4 was upregulated in 22/32 pairs of tissue samples at stage III &IV (P=0.0069). Knockdown of ACTN4 in GC cells showed no significant effect on cell proliferation, but significantly increased cell-matrix adhesion, as well as reduced migration and invasion of AGS, MKN7 and NCI-N87 cells. We found that NF-κB was downregulated in GC with the knockdown of ACTN4. In conclusion, this is the first study to indicate that ACTN4 is significantly upregulated in patients with metastatic GC. ACTN4 reduces cell adhesion and enhances migration and invasion of GC cells and may therefore be a novel therapeutic target for GC.

Role of Forkhead Box Class O proteins in cancer progression and metastasis

It is now widely accepted that several gene alterations including transcription factors are critically involved in cancer progression and metastasis. Forkhead Box Class O proteins (FoxOs) including FoxO1/FKHR, FoxO3/FKHRL1, FoxO4/AFX and FoxO6 transcription factors are known to play key roles in proliferation, apoptosis, metastasis, cell metabolism, aging and cancer biology through their phosphorylation, ubiquitination, acetylation and methylation. Though FoxOs are proved to be mainly regulated by upstream phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3 K)/Akt signaling pathway, the role of FoxOs in cancer progression and metastasis still remains unclear so far. Thus, with previous experimental evidences, the present review discussed the role of FoxOs in association with metastasis related molecules including cannabinoid receptor 1 (CNR1), Cdc25A/Cdk2, Src, serum and glucocorticoid inducible kinases (SGKs), CXCR4, E-cadherin, annexin A8 (ANXA8), Zinc finger E-box-binding homeobox 2 (ZEB2), human epidermal growth factor receptor 2 (HER2) and mRNAs such as miR-182, miR-135b, miR-499-5p, miR-1274a, miR-150, miR-34b/c and miR-622, subsequently analyzed the molecular mechanism of some natural compounds targeting FoxOs and finally suggested future research directions in cancer progression and metastasis.

FOXO1 Suppression is a Determinant of Acquired Lapatinib-Resistance in HER2-Positive Gastric Cancer Cells Through MET Upregulation

Purpose

Lapatinib is a candidate drug for treatment of trastuzumab-resistant, human epidermal growth factor receptor 2 (HER2)–positive gastric cancer (GC). Unfortunately, lapatinib resistance renders this drug ineffective. The present study investigated the implication of forkhead box O1 (FOXO1) signaling in the acquired lapatinib resistance in HER2-positive GC cells.

Materials and Methods

Lapatinib-resistant GC cell lines (SNU-216 LR2-8) were generated in vitro by chronic exposure of lapatinib-sensitive, HER2-positive SNU-216 cells to lapatinib. SNU-216 LR cells with FOXO1 overexpression were generated by stable transfection of a constitutively active FOXO1 mutant (FOXO1A3). HER2 and MET in SNU-216 LR cells were downregulated using RNA interference. The sensitivity of GC cells to lapatinib and/or cisplatin was determined by crystal violet assay. In addition, Western blot analysis, luciferase reporter assay and reverse transcription–polymerase chain reaction were performed.

Results

SNU-216 LR cells showed upregulations of HER2 and MET, but downregulation of FOXO1 compared to parental SNU-216 cells. FOXO1 overexpression in SNU-216 LR cells significantly suppressed resistance to lapatinib and/or cisplatin. In addition, FOXO1 negatively controlled HER2 and MET at the transcriptional level and was negatively controlled by these molecules at the post-transcriptional level. A positive crosstalk was shown between HER2 and MET, each of which increased resistance to lapatinib and/or cisplatin.

Conclusion

FOXO1 serves as an important linker between HER2 and MET signaling pathways through negative crosstalks and is a key regulator of the acquired lapatinib resistance in HER2-positive GC cells. These findings provide a rationale for establishing a novel treatment strategy to overcome lapatinib resistance in a subtype of GC patients.

HER2-induced metastasis is mediated by AKT/JNK/EMT signaling pathway in gastric cancer

AIM

To investigated the relationships between HER2, c-Jun N-terminal kinase (JNK) and protein kinase B (AKT) with respect to metastatic potential of HER2-positive gastric cancer (GC) cells.

METHODS

Immunohistochemistry was performed on tissue array slides containing 423 human GC specimens. Using HER2-positve GC cell lines SNU-216 and NCI-N87, HER2 expression was silenced by RNA interference, and the activations of JNK and AKT were suppressed by SP600125 and LY294002, respectively. Transwell assay, Western blot, semi-quantitative reverse transcription-polymerase chain reaction and immunofluorescence staining were used in cell culture experiments.

RESULTS

In GC specimens, HER2, JNK, and AKT activations were positively correlated with each other. In vitro analysis revealed a positive regulatory feedback loop between HER2 and JNK in GC cell lines and the role of JNK as a downstream effector of AKT in the HER2/AKT signaling pathway. JNK inhibition suppressed migratory capacity through reversing EMT and dual inhibition of JNK and AKT induced a more profound effect on cancer cell motility.

CONCLUSION

HER2, JNK and AKT in human GC specimens are positively associated with each other. JNK and AKT, downstream effectors of HER2, co-operatively contribute to the metastatic potential of HER2-positive GC cells. Thus, targeting of these two molecules in combination with HER2 downregulation may be a good approach to combat HER2-positive GC.

Nuclear PRMT1 expression is associated with poor prognosis and chemosensitivity in gastric cancer patients

BACKGROUND

Metastatic and refractory gastric cancer (GC) are associated with a poor prognosis; therefore, the identification of prognostic factors and chemosensitivity markers is extremely important. Protein arginine methyltransferase 1 (PRMT1) may play a role in chemosensitivity/apoptosis induction via activation of the tumor suppressor forkhead box O1 (FOXO1). The purpose of this study was to clarify the expression of and relationship between PRMT1 and FOXO1 to evaluate the applicability of PRMT1 as a prognostic marker and a therapeutic tool in GC.

METHODS

We investigated the clinical and functional significance of PRMT1 and FOXO1 in 195 clinical GC samples using immunohistochemistry. We performed suppression analysis of PRMT1 using small interfering RNA to determine the biological roles of PRMT1 in chemosensitivity.

RESULTS

PRMT1 and FOXO1 in GC samples were predominantly expressed in the nucleus. Patients with lower PRMT1 expression (n = 131) had suppressed nuclear accumulation of FOXO1, higher recurrence after adjuvant chemotherapy, and poorer prognosis than those with higher PRMT1 expression (n = 64). PRMT1 downregulation in GC cells by RNA interference inhibited cisplatin and 5-fluorouracil sensitivity. The expression of phosphorylated FOXO1 and phosphorylated BCL-2 antagonist of cell death was upregulated in PRMT1 small interfering RNA groups.

CONCLUSION

Our data suggest that the evaluation of PRMT1 expression in GC is a useful predictor of poor prognosis and recurrence after adjuvant chemotherapy. Moreover, these data suggest that PRMT1 is a promising therapeutic tool for overcoming refractory GC.

Forkhead transcription factors: new considerations for alzheimer's disease and dementia

Life expectancy of individuals in both developed and undeveloped nations continues to rise at an unprecedented rate. Coupled to this increase in longevity for individuals is the rise in the incidence of chronic neurodegenerative disorders that includes Alzheimer's disease (AD). Currently, almost ten percent of the population over the age of 65 suffers from AD, a disorder that is presently without definitive therapy to prevent the onset or progression of cognitive loss. Yet, it is estimated that AD will continue to significantly increase throughout the world to impact millions of individuals and foster the escalation of healthcare costs. One potential target for the development of novel strategies against AD and other cognitive disorders involves the mammalian forkhead transcription factors of the O class (FoxOs). FoxOs are present in "cognitive centers" of the brain to include the hippocampus, the amygdala, and the nucleus accumbens and may be required for memory formation and consolidation. FoxOs play a critical role in determining survival of multiple cell types in the nervous system, drive pathways of apoptosis and autophagy, and control stem cell proliferation and differentiation. FoxOs also interface with multiple cellular pathways that include growth factors, Wnt signaling, Wnt1 inducible signaling pathway protein 1 (WISP1), and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) that ultimately may control FoxOs and determine the fate and function of cells in the nervous system that control memory and cognition. Future work that can further elucidate the complex relationship FoxOs hold over cell fate and cognitive function could yield exciting prospects for the treatment of a number of neurodegenerative disorders including AD.

Bufalin reverses intrinsic and acquired drug resistance to cisplatin through the AKT signaling pathway in gastric cancer cells

Cisplatin is the most common chemotherapeutic agent for gastric cancer (GC), however it activates AKT, which contributes to intrinsic and acquired resistance. Bufalin, a traditional Chinese medicine, shows significant anticancer activity by inhibiting the AKT pathway. It was therefore hypothesized that bufalin could counteract cisplatin resistance in GC cells. SGC7901, MKN‑45 and BGC823 human GC cells were cultured under normoxic and hypoxic conditions. Effects of cisplatin and bufalin on GC cells were measured by a cell counting kit, apoptosis was analyzed by flow cytometry, and immunoblotting was used to detect proteins associated with the AKT signaling pathway. It was demonstrated that bufalin synergized with cisplatin to inhibit proliferation and promote apoptosis of GC cells by diminishing the activation of cisplatin-induced AKT under normoxic and hypoxic conditions. Bufalin also inhibits cisplatin-activated molecules downstream of AKT that affect proliferation and apoptosis, including glycogen synthase kinase, mammalian target of rapamycin, ribosomal protein S6 Kinase and eukaryotic translation initiation factor-4E-binding protein-1. To investigate acquired cisplatin resistance, a cisplatin‑resistant cell line SGC7901‑CR was used. It was demonstrated that bufalin reversed acquired cisplatin resistance and significantly induced apoptosis through the AKT pathway. These results imply that bufalin could extend the therapeutic effect of cisplatin on GC cells when administered in combination.

miR-3188 regulates nasopharyngeal carcinoma proliferation and chemosensitivity through a FOXO1-modulated positive feedback loop with mTOR-p-PI3K/AKT-c-JUN

The biological role of miR-3188 has not yet been reported in the context of cancer. In this study, we observe that miR-3188 not only reduces cell-cycle transition and proliferation, but also significantly prolongs the survival time of tumour-bearing mice as well as sensitizes cells to 5-FU. Mechanistic analyses indicate that miR-3188 directly targets mTOR to inactivate p-PI3K/p-AKT/c-JUN and induces its own expression. This feedback loop further suppresses cell-cycle signalling through the p-PI3K/p-AKT/p-mTOR pathway. Interestingly, we also observe that miR-3188 direct targeting of mTOR is mediated by FOXO1 suppression of p-PI3K/p-AKT/c-JUN signalling. In clinical samples, reduced miR-3188 is an unfavourable factor and negatively correlates with mTOR and c-JUN levels but positively correlates with FOXO1 expression. Our studies demonstrate that as a tumour suppressor, miR-3188 directly targets mTOR to stimulate its own expression and participates in FOXO1-mediated repression of cell growth, tumorigenesis and NPC chemotherapy resistance.

Although miR-related mechanisms have been implicated in nasopharyngeal carcinoma (NPC), a precise role for miR-3188 has not been reported in this context. Here, Zhao et al. show that FOXO1-induced miR-3188 acts as a tumour suppressor in NPC by regulating the axis mTOR/PI3K/Akt/c-Jun.

Loss of FOXO1 promotes gastric tumour growth and metastasis through upregulation of human epidermal growth factor receptor 2/neu expression

BACKGROUND

The biological significance of FOXO1, a member of the forkhead box O transcription factor family, in gastric cancer (GC) remains unclear. The present study provides direct evidence of the role of FOXO1 in tumour growth and metastasis of GC in relation to human epidermal growth factor receptor 2 (HER2).

METHODS

The expressions of FOXO1 and HER2 were modulated in GC cell lines (SNU-638, MKN45, SNU-216 and NCI-N87) by stable transfections. The effects of transfection on GC phenotypes were evaluated in vitro and in animal models. In addition, the relationship between FOXO1 and HER2 was analysed using GC clinical specimens, cell lines and xenografts.

RESULTS

FOXO1 silencing in GC cells increased colony formation and mesenchymal transition in vitro, as well as tumour growth and metastasis in nude mice, whereas HER2 silencing induced the opposite results.. Furthermore, an inverse relationship between FOXO1 and HER2 was found in clinical specimens of GC, GC cells and GC xenograft tumours. Although a negative crosstalk between these two molecules was shown, double knockdown of both FOXO1 and HER2 in GC cells revealed that HER2 silencing reversed the FOXO1 shRNA-induced migration and invasion even without the FOXO1 restoration.

CONCLUSIONS

Our results indicate that loss of FOXO1 promotes GC growth and metastasis by upregulating HER2 expression and that the HER2 expression is more critical to the induction of GC cell metastasis. The present study provides evidence that the FOXO1/HER2 pathway may regulate GC progression in a subgroup of GC patients.

FoxO proteins in the nervous system

Acute as well as chronic disorders of the nervous system lead to significant morbidity and mortality for millions of individuals globally. Given the ability to govern stem cell proliferation and differentiated cell survival, mammalian forkhead transcription factors of the forkhead box class O (FoxO) are increasingly being identified as potential targets for disorders of the nervous system, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and auditory neuronal disease. FoxO proteins are present throughout the body, but they are selectively expressed in the nervous system and have diverse biological functions. The forkhead O class transcription factors interface with an array of signal transduction pathways that include protein kinase B (Akt), serum- and glucocorticoid-inducible protein kinase (SgK), IκB kinase (IKK), silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), growth factors, and Wnt signaling that can determine the activity and integrity of FoxO proteins. Ultimately, there exists a complex interplay between FoxO proteins and their signal transduction pathways that can significantly impact programmed cell death pathways of apoptosis and autophagy as well as the development of clinical strategies for the treatment of neurodegenerative disorders.

Licochalcone A-induced human gastric cancer BGC-823 cells apoptosis by regulating ROS-mediated MAPKs and PI3K/AKT signaling pathways

Both phosphatidylinositol 3-kinase (PI3K)/AKT and mitogen activated protein kinase (MAPK) signaling cascades play an important role in cell proliferation, survival, angiogenesis, and metastasis of tumor cells. In the present report, we investigated the effects of licochalcone A (LA), a flavonoid extracted from licorice root, on the PI3K/AKT/mTOR and MAPK activation pathways in human gastric cancer BGC-823 cells. LA increased reactive oxygen species (ROS) levels, which is associated with the induction of apoptosis as characterized by positive Annexin V binding and activation of caspase-3, and cleavage of poly-ADP-ribose polymerase (PARP). Inhibition of ROS generation by N-acetylcysteine (NAC) significantly prevented LA-induced apoptosis. Interestingly, we also observed that LA caused the activation of ERK, JNK, and p38 MAPK in BGC-823 cells. The antitumour activity of LA-treated BGC-823 cells was significantly distinct in KM mice in vivo. All the findings from our study suggest that LA can interfere with MAPK signaling cascades, initiate ROS generation, induce oxidative stress and consequently cause BGC cell apoptosis.

Polymorphisms in microRNA target sites of forkhead box O genes are associated with hepatocellular carcinoma

The forkhead box O (FOXO) transcription factors play important roles in various cancer development including Hepatocellular Carcinoma (HCC). In this study we conducted a hospital-based case control study including 1049 cases (HCC patients) and 1052 controls (non-tumor patients) to examine whether single nucleotide polymorphisms (SNPs) within microRNA (miRNA) target sites of FOXO genes confer HCC susceptibility. A total of three miRNA target site SNPs in the 3’ untranslated regions (UTR) of FOXO1 (rs17592236), FOXO3 (rs4946936) and FOXO4 (rs4503258) were analyzed. No statistically significant differences were found in genotype distribution for rs17592236, rs4946936, and rs4503258 between the HCC patient group and the tumor-free control group using single factor chi-square analysis (P>0.05). However, multivariate logistic regression analysis showed that the CT/TT genotype in rs17592236 was significantly associated with decreased risk of HCC development (P = 0.010, OR = 0.699, 95% CI: 0.526–0.927) as compared to the CC genotype in rs17592236. Additionally, a genetic interaction was found between rs17592236 and rs4503258 (P = 0.003, OR = 0.755, 95% CI: 0.628–0.908). Functional dual luciferase reporter assays verified that the rs17592236 SNP was a target site of human miRNA miR-137. Together, these results indicate that the rs17592236 polymorphism is associated with decreasing of HCC hereditary susceptibility likely through modulating the binding affinity of miR-137 to the 3’UTR in FOXO1 messenger RNA (mRNA). Further knowledge obtained from this study may provide important evidence for the prevention and targeted therapy of HCC.

Diverse roles of SIRT1 in cancer biology and lipid metabolism

SIRT1, an NAD⁺-dependent deacetylase, has been described in the literature as a major player in the regulation of cellular stress responses. Its expression has been shown to be altered in cancer cells, and it targets both histone and non-histone proteins for deacetylation and thereby alters metabolic programs in response to diverse physiological stress. Interestingly, many of the metabolic pathways that are influenced by SIRT1 are also altered in tumor development. Not only does SIRT1 have the potential to regulate oncogenic factors, it also orchestrates many aspects of metabolism and lipid regulation and recent reports are beginning to connect these areas. SIRT1 influences pathways that provide an alternative means of deriving energy (such as fatty acid oxidation and gluconeogenesis) when a cell encounters nutritive stress, and can therefore lead to altered lipid metabolism in various pathophysiological contexts. This review helps to show the various connections between SIRT1 and major pathways in cellular metabolism and the consequence of SIRT1 deregulation on carcinogenesis and lipid metabolism.

FoxO Transcription Factors and Regenerative Pathways in Diabetes Mellitus

Mammalian forkhead transcription factors of the O class (FoxO) are exciting targets under consideration for the development of new clinical entities to treat metabolic disorders and diabetes mellitus (DM). DM, a disorder that currently affects greater than 350 million individuals globally, can become a devastating disease that leads to cellular injury through oxidative stress pathways and affects multiple systems of the body. FoxO proteins can regulate insulin signaling, gluconeogenesis, insulin resistance, immune cell migration, and cell senescence. FoxO proteins also control cell fate through oxidative stress and pathways of autophagy and apoptosis that either lead to tissue regeneration or cell demise. Furthermore, FoxO signaling can be dependent upon signal transduction pathways that include silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), Wnt, and Wnt1 inducible signaling pathway protein 1 (WISP1). Cellular metabolic pathways driven by FoxO proteins are complex, can lead to variable clinical outcomes, and require in-depth analysis of the epigenetic and post-translation protein modifications that drive FoxO protein activation and degradation.

The FOXM1-induced resistance to oxaliplatin is partially mediated by its novel target gene Mcl-1 in gastric cancer cells

Myeloid cell leukemia-1 (Mcl-1) is an anti-apoptotic protein that belongs to the Bcl-2 family. The aberrant expression of Mcl-1 is important for sensitivity to chemotherapy drugs in gastric cancer. However, the regulatory mechanism of Mcl-1 in gastric cancer cells remains unclear. In this study, we first found that Forkhead box M1 (FOXM1) and Mcl-1 expression levels were positively correlated in human gastric cancer specimens and that both are associated with poor prognosis of patients treated with oxaliplatin. Second, we demonstrated that the expression level of Mcl-1 was correlated with FOXM1 expression in gastric cancer cells. Third, reporter assays showed that FOXM1 upregulated the promoter activity of the Mcl-1 gene. Electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP) assays further demonstrated that FOXM1 could bind to a particular site (-635acaaacaa-628) in the promoter region of the Mcl-1 gene. Moreover, CCK-8 assays and analyses of apoptosis revealed that the suppression of the FOXM1/Mcl-1 pathway induced apoptosis and thus increased sensitivity to oxaliplatin in gastric cancer cells, whereas the enhancement of the FOXM1/Mcl-1 pathway inhibited apoptosis and decreased sensitivity to oxaliplatin in gastric cancer cells. Taken together, this study is the first to not only show that Mcl-1 is a novel target gene of FOXM1 but also suggest that targeting FOXM1/Mcl-1 may be a novel strategy to enhance sensitivity to oxaliplatin in gastric cancer.

The Role of PI3K/Akt/mTOR Signaling in Gastric Carcinoma

The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is one of the key signaling pathways induced by various receptor-tyrosine kinases. Accumulating evidence shows that this pathway is an important promoter of cell growth, metabolism, survival, metastasis, and resistance to chemotherapy. Genetic alterations in the PI3K/Akt/mTOR pathway in gastric carcinoma have often been demonstrated. Many kinds of molecular targeting therapies are currently undergoing clinical testing in patients with solid tumors. However, with the exception of the ErbB2-targeting antibody, targeting agents, including PI3K/Akt/mTOR inhibitors, have not been approved for treatment of patients with gastric carcinoma. This review summarizes the current knowledge on PI3K/Akt/mTOR signaling in the pathogenesis of gastric carcinoma and the possible therapeutic targets for gastric carcinoma. Improved knowledge of the PI3K/Akt/mTOR pathway in gastric carcinoma will be useful in understanding the mechanisms of tumor development and for identifying ideal targets of anticancer therapy for gastric carcinoma.