Knockdown of Rap1b Enhances Apoptosis and Autophagy in Gastric Cancer Cells via the PI3K/Akt/mTOR Pathway

Comparative transcriptomic analysis of hepatopancreas reveals that more genes are involved in the exposure response of Vibrio parahaemolyticus PirAvp compared to PirBvp

Vibrio parahaemolyticus (VP-AHPND) is regarded as one of the main pathogens that caused acute hepatopancreatic necrosis disease (AHPND) in the Pacific white shrimp Litopenaeus vannamei. PirAvp and PirBvp toxin proteins are the main pathogenic proteins of AHPND in shrimp. Knowledge about the mechanism of shrimp response to PirAvp or PirBvp toxin is very helpful for developing new prevention and control strategy of AHPND in shrimp. In this study, the pathological sections showed that after 4 h treatment, significant pathological changes were observed in the PirBvp treated group, and no obvious pathological changes was found in PirAvp treated group. In order to learn the mechanism of shrimp response to PirAvp and PirBvp, comparative transcriptome was applied to analyze the different expressions of genes in the hepatopancreas of shrimp after treatment with PirAvp or PirBvp. A total of 9978 differentially expressed genes (DEGs) were identified between PirAvp or PirBvp-treated and PBS control shrimp, including 6616 DEGs in the PirAvp treated group and 3362 DEGs in the PirBvp treated group. There were 2263 DEGs that were commonly expressed, 4353 DEGs were only expressed in PirAvp VS PBS group and 1099 DEGs were uniquely expressed in PirBvp VS PBS group. Among these DEGs, the anti-apoptosis related pathways and immune response related genes significantly expressed in the commonly expressed DEGs of PirAvp VS PBS group and PirBvp VS PBS group, and small GTPase-mediated signaling and DNA metabolic process might relate to the host special reaction towards PirAvp and PirBvp exposure. The data suggested that the differential expression of these immune and metabolic-related genes in hepatopancreas might contribute to the pathogenicity variations of shrimp to VP-AHPND. The identified genes in this study will be useful for clarifying the response mechanism of shrimp toward different toxins of VP-AHPND and will further provide molecular basis for understanding the pathogenic mechanism of VP-AHPND.

SNORA70E promotes the occurrence and development of ovarian cancer through pseudouridylation modification of RAP1B and alternative splicing of PARPBP

The present study demonstrated for the first time that SNORA70E, which belongs to box H/ACA small nucleolar noncoding RNAs (snoRNAs) who could bind and induce pseudouridylation of RNAs, was significantly elevated in ovarian cancer tissues and was an unfavourable prognostic factor of ovarian cancer. The over‐expression of SNORA70E showed increased cell proliferation, invasion and migration in vitro and induced tumour growth in vivo. Further research found that SNORA70E regulates RAS‐Related Protein 1B (RAP1B) mRNA through pseudouracil modification by combing with the pyrimidine synthase Dyskerin Pseudouridine Synthase 1 (DKC1) and increase RAP1B protein level. What's more, the silencing of DKC1/RAP1B in SNORA70E overexpression cells both inhibited cell proliferation, migration and invasion through reducing β‐catenin, PI3K, AKT1, mTOR, and MMP9 protein levels. Besides, RNA‐Seq results revealed that SNORA70E regulates the alternative splicing of PARP‐1 binding protein (PARPBP), leading to the 4th exon‐skipping in PARPBP‐88, forming a new transcript PARPBP‐15, which promoted cell invasion, migration and proliferation. Finally, ASO‐mediated silencing of SNORA70E could inhibit ovarian cancer cell proliferation, invasion, migration ability in vitro and inhibit tumorigenicity in vivo. In conclusion, SNORA70E promotes the occurrence and development of ovarian cancer through pseudouridylation modification of RAP1B and alternative splicing of PARPBP. Our results demonstrated that SNORA70E may be a new diagnostic and therapeutic target for ovarian cancer.

DF-1 cells prevent MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis

Mycoplasma gallisepticum (MG) is a major poultry pathogen that can induce Chronic Respiratory Disease (CRD) in chickens, causing serious economic losses in the poultry industry worldwide. Increasing evidence suggests that microRNAs (miRNAs) act as a vital role in resisting microbial pathogenesis and maintaining cellular mechanism. Our previous miRNAs sequencing data showed gga-miR-24-3p expression level was significantly increased in MG-infected chicken lungs. The aim of this study is to reveal the cellular mechanism behind the MG-HS infection. We found that gga-miR-24-3p was significantly upregulated and Ras-related protein-B (RAP1B) was downregulated in chicken fibroblast cells (DF-1) with MG infection. Dual luciferase reporting assay and rescue assay confirmed that RAP1B was the target gene of gga-miR-24-3p. Meanwhile, overexpressed gga-miR-24-3p increased the levels of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), and significantly inhibited cell proliferation as well as promoted MG-infected DF-1 cell apoptosis, whereas inhibition of gga-miR-24-3p had the opposite effect. More importantly, the results of overexpression and knockdown of target gene RAP1B demonstrated that the presence of RAP1B promoted cell proliferation and it saved the reduced or increased cell proliferation caused by overexpression or inhibition of gga-miR-24-3p. Furthermore, the overexpression of gga-miR-24-3p could significantly inhibit the expression of MG-HS adhesion protein. Taken together, these findings demonstrate that DF-1 cells can resist MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis, which provides a new mechanism of resistance to MG infection in vitro.

Integrated Analysis of lncRNA-Associated ceRNA Network Identifies Two lncRNA Signatures as a Prognostic Biomarker in Gastric Cancer

Background

Gastric cancer (GC) is a malignant tumour that originates in the gastric mucosal epithelium and is associated with high mortality rates worldwide. Long noncoding RNAs (lncRNAs) have been identified to play an important role in the development of various tumours, including GC. Yet, lncRNA biomarkers in a competing endogenous RNA network (ceRNA network) that are used to predict survival prognosis remain lacking. The aim of this study was to construct a ceRNA network and identify the lncRNA signature as prognostic factors for survival prediction.

Methods

The lncRNAs with overall survival significance were used to construct the ceRNA network. Function enrichment, protein-protein interaction, and cluster analysis were performed for dysregulated mRNAs. Multivariate Cox proportional hazards regression was performed to screen the potential prognostic lncRNAs. RT-qPCR was used to measure the relative expression levels of lncRNAs in cell lines. CCK8 assay was used to assess the proliferation of GC cells transfected with sh-lncRNAs.

Results

Differentially expressed genes were identified including 585 lncRNAs, 144 miRNAs, and 2794 mRNAs. The ceRNA network was constructed using 35 DElncRNAs associated with overall survival of GC patients. Functional analysis revealed that these dysregulated mRNAs were enriched in cancer-related pathways, including TGF-beta, Rap 1, calcium, and the cGMP-PKG signalling pathway. A multivariate Cox regression analysis and cumulative risk score suggested that two of those lncRNAs (LINC01644 and LINC01697) had significant prognostic value. Furthermore, the results indicate that LINC01644 and LINC01697 were upregulated in GC cells. Knockdown of LINC01644 or LINC01697 suppressed the proliferation of GC cells.

Conclusions

The authors identified 2-lncRNA signature in ceRNA regulatory network as prognostic biomarkers for the prediction of GC patient survival and revealed that silencing LINC01644 or LINC01697 inhibited the proliferation of GC cells.

Silencing of circ_0078607 prevents development of gastric cancer and inactivates the ERK1/2/AKT pathway through the miR-188-3p/RAP1B axis

The aim of this study is to explore the expression and mechanism of circ_0078607 on proliferation and apoptosis of gastric cancer. Real time PCR (RT-PCR) was performed to detect the expression of circ_0078607 in gastric cancer tumor tissues, plasma and cell lines. Cell viability was detected by cell counting Kit-8. Cell proliferation ability was assessed by cell cycle assay. The samples were analyzed by flow cytometry for the detection of apoptosis. Luciferase assay and RNA immunoprecipitation (RIP) were carried out to verify the relationship between circ_0078607 and miR-188-3p, miR-188-3p, and RAP1B. Western blot was employed to detect the protein level of RAP1B, ERK1/2 and AKT. In vivo, the effect of circ_0078607 on gastric cancer tumor growth was detected by lentivirus vector injection. Here, we found the increased level of circ_0078607 in gastric cancer tissues, gastric cancer patients plasma and cell lines. Knockdown of circ_0078607 could prevent proliferation and induce cell apoptosis in MKN-28 cells. Then we verified that circ_0078607 could interact with miR-188-3p by performed luciferase assay and RIP. Furthermore, we observed that RAP1B was a potential target of miR-188-3p. Next, we found that miR-188-3p inhibitor or overexpression of RAP1B could prevent the anti-tumor function of sh-circ_0078607. Silencing of circ_0078607 inhibited ERK1/2/AKT signal pathways via regulating miR-188-3p/RAP1B. In vivo, knockdown of circ_0078607 inhibited tumor growth. Knockdown of circ_0078607 inhibits the proliferation and induces apoptosis of gastric cancer via miR-188-3p/RAP1B signal pathway.

Prognostic and immunological role of Ras-related protein Rap1b in pan-cancer

Ras-related Protein Rap1b, a GTP-binding protein belonging to the proximal RAS, which affects tumor progression through regulating tumor cell proliferation, invasion and participates in the functions of various immune cells. However, the potential roles and mechanisms of Rap1b in tumor progression and immunology remains unclear. In this study, we systematically analyzed the pan-cancer expression and prognostic correlation of Rap1b based on GTEX, CCLE, Oncomine, PrognoScan, Kaplan–Meier plotters and TCGA databases. The potential correlations of Rap1b with immune infiltration were revealed via TIMER and TCGA database. SangerBox database was used to analyzed the correlations between Rap1b expression and immune checkpoint (ICP), tumor mutational burden (TMB), microsatellite instability (MSI), mismatch repairs (MMRs) and DNA methylation. The results indicated that the expression level of Rap1b varies in different tumors. Meanwhile, the expression level of Rap1b strongly correlated with prognosis in patients with tumors, higher expression of Rap1b usually was linked to poor prognosis in different datasets. Rap1b was correlated closely with tumor immunity and interacted with various immune cells in different types of cancers. In addition, there were significant positive correlations between Rap1b expression and ICP, TMB, MSI, MMRs and DNA methylation. In conclusion, the results of pan-cancer analysis showed that the abnormal Rap1b expression was related to poor prognosis and tumor immune infiltration in different cancers. Furthermore, Rap1b gene may be used as a potential biomarker of clinical tumor prognosis.

Procyanidin B2 induces apoptosis and autophagy in gastric cancer cells by inhibiting Akt/mTOR signaling pathway

Background

Procyanidin B2 (PB2), a unique component of the grape seed and other medicinal plants. PB2 has shown wide anticancer activity in various human cancer cells. However, it remains unclear about the biological effects and associated mechanisms of PB2 on gastric cancer cells.

Methods

Cell proliferation was measured by CCK8 assay, and cellular lactate dehydrogenase (LDH) release was measured in the culture medium. Cellular apoptosis was observed via TUNEL staining assay and measured by caspase-3 and -9 activities. Autophagy was observed by LC3 staining. Western blot analysis was performed to verify autophagy-associated proteins (Beclin1 and Atg5) and Akt-mTOR pathway.

Results

PB2 reduced the viability of BGC-823 and SGC-7901 cells in a concentration-dependent manner. Furthermore, PB2 induced increased apoptosis rate of gastric cancer cells and enhanced caspase-3 and -9 activities. Simultaneously, PB2 triggered autophagy in gastric cancer cells, with enhanced LC3 staining and increased expression of Beclin1 and Atg5, while the inhibition of autophagy by 3-MA reversed the PB2-induced suppression on cell viability. In addition, PB2 significantly decreased p-Akt and p-mTOR protein expression of gastric cancer cells.

Conclusion

PB2 exerts anti-proliferative and apoptotic effects and induces autophagy by modulating Akt/mTOR signaling pathway. PB2 may be developed as a potential therapeutic drug for gastric cancer.

MicroRNA-101 suppresses colorectal cancer progression by negative regulation of Rap1b

Colorectal cancer (CRC) is the fourth most lethal malignancy and is the second most common cause of cancer-associated mortality worldwide. The development of high-throughput sequencing has enabled the identification of potential biomarkers for the diagnosis and treatment of various types of cancer. Although microRNA-101 (miR-101) has been demonstrated to be a potential biomarker of CRC, its detailed mechanisms remain to be fully discovered. In the present study, overall survival analysis was applied to determine the association between miR-101 and CRC prognosis. Reverse transcription-quantitative PCR (RT-qPCR) was used to examine gene expression levels in tissues and cells. Cell proliferative and apoptotic activities were determined by MTT and flow cytometry assays, respectively. Wound healing and Transwell assays were used to examine CRC cell migration and invasion, respectively. In the present study, RT-qPCR analysis indicated that miR-101 was significantly downregulated in CRC tissues and cells. However, clinical data collected from The Cancer Genome Atlas revealed no significant association between the expression levels of miR-101 and the prognosis of CRC. Additionally, miR-101 inhibited the progression of CRC by directly binding to the 3′-untranslated region of Ras-related protein Rap1b (Rap1b). This was associated with downregulation of Rap1b expression. Furthermore, the overexpression of Rap1b promoted miR-101 mimic-attenuated CRC cell progression. The present study demonstrated that miR-101 may be involved in the repression of the CRC progression by forming a negative feedback loop with Rap1b. The findings revealed the interaction between miR-101 and Rap1b during the progression of CRC, which could aid the development of therapeutic strategies.

TNF-α regulates the early development of avascular necrosis of the femoral head by mediating osteoblast autophagy and apoptosis via the p38 MAPK/NF-κB signaling pathway

Previous studies have shown that the tumor necrosis factor-α (TNF-α) levels in serum and bone tissues formed in avascular necrosis of femoral head (ANFH) patients were higher than those of normal individuals, indicating TNF-α might play a role in the pathogenesis of ANFH. However, the underlying mechanisms remain unclear. Hematoxylin and eosin staining was performed to show the pathological changes of ANFH bone tissues. TNF-α expression in normal and ANFH tissues was examined by quantitative real-time polymerase chain reaction and western blot analyses. Osteoblast autophagy and apoptosis, as well as signaling pathways activation, were measured by their corresponding marker proteins. Osteoblast proliferation, autophagy, and apoptosis were evaluated using cell counting kit-8, transmission electron microscopy, and flow cytometry. The structures of bone tissues of ANFH were obviously damaged. TNF-α expression was significantly upregulated in ANFH bone tissues compared to normal tissues. Autophagy and apoptosis were remarkably promoted, and p38 mitogen-activated protein kinase (MAPK)/nuclear factor-κB (NF-κB) signaling pathways were markedly activated in ANFH. Suppression of the p38 MAPK/NF-κB pathway significantly attenuated the TNF-α-induced autophagy, however, enhanced the TNF-α-induced apoptosis in osteoblasts. Increased TNF-α in ANFH regulated osteoblast autophagy and apoptosis by p38 MAPK/NF-κB signaling pathways, blocking the pathway by inhibitors exacerbated TNF-α-induced apoptosis through impairing autophagy flux.

Long Noncoding RNA LUADT1 Is Upregulated in Melanoma and May Sponge miR-28-5p to Upregulate RAP1B

Background: Long noncoding RNA (lncRNA) LUADT1 is a known oncogenic lncRNA in lung cancer. This study aimed to explore the roles of LUADT1 in melanoma. Materials and Methods: Sixty pairs of melanoma and nontumor tissues were obtained from 60 melanoma patients (37 men and 23 women, 38-68 years, 52.1 ± 4.9 years) at the First Affiliated Hospital of Zhejiang University School of Medicine. Gene expression was analyzed by quantitative polymerase chain reaction and western blot. Cell transfections were performed to analyze gene expression. Results: We found that LUADT1 was upregulated in melanoma and high levels of LUADT1 predicted poor survival. RNA interaction prediction showed that LUADT1 can form base pairing with miR-28-5p. In melanoma cells, LUADT1 overexpression mediated the upregulated Ras-related protein Rap-1b (RAP1B). Cell proliferation assay showed that LUADT1 and RAP1B overexpression mediated the increased proliferation rate of melanoma cells. In addition, miR-28-5p overexpression played opposite roles attenuating the effects of LUADT1 overexpression on both RAP1B expression and cancer cell proliferation. Conclusions: LUADT1 in melanoma and may sponge miR-28-5p to upregulate RAP1B, thereby promoting cancer cell proliferation.

Cordyceps sinensis attenuates HBx‑induced cell apoptosis in HK‑2 cells through suppressing the PI3K/Akt pathway

The authors' previous studies demonstrated that the major renal damage from hepatitis B virus infection is HBx‑induced apoptosis of renal tubular epithelial cells. Cordyceps sinensis is one of the most valuable of traditional Chinese medicines and is extensively used to treat chronic renal diseases. However, there is no research on the potential renal protective effect of C. sinensis on HBx‑induced apoptosis of renal tubular cells. The protective effect and underlying mechanism of C. sinensis were examined using a renal tubular epithelial cell line stably overexpressing HBx. HK‑2 cells were stably transfected with pCMV‑HBx to establish HBx‑overexpression in an in vitro cell model and HK‑2 cells transfected with an empty vector were generated as a control. The effect of C. sinensis on cell proliferation and apoptosis, the phosphatidylinositol‑3‑kinase (PI3K)/protein kinase B (Akt) signaling pathway, and the enzyme activity of caspase‑3 and caspase‑9 was measured. The present study demonstrated that HBx transfection inhibited cell proliferation; increased apoptosis, caspase‑3 and caspase‑9 activity; and increased the activity of the PI3K/Akt pathway. Treatment with C. sinensis attenuated all of these HBx‑induced responses. HBx triggered apoptosis and activated the PI3K/Akt signaling pathway in HK‑2 cells. C. sinensis treatment significantly attenuated the effect of HBx, at least in part by suppressing the PI3K/Akt signaling pathway.

LncRNA LOXL1-AS1 promotes endometrial cancer progression by sponging miR-28-5p to upregulate RAP1B expression

BACKGROUND

Increasing lncRNAs are found to be involved in the biological process of multiple cancer types. Herein, we aimed to reveal the role of LOXL1-AS1 in endometrial cancer (EC) progression.

METHODS

Tumor and corresponding normal tissues were obtained from EC patients. Si-LOXL1-AS1 and miR-28-5p inhibitor were transfected to downregulate the expressions of LOXL1-AS1 and miR-28-5p, while miR-28-5p mimics were used to upregulate the miR-28-5p expression. CCK-8 and colony assays were applied to estimate the cell proliferation. Flow cytometry was performed to measure the cell apoptosis. Wound healing and transwell assays were conducted to assess the cell migration and invasion abilities. Informatics analysis was used to explore the relationship among LOXL1-AS1, miR-28-5p and RAP1B.

RESULTS

LOXL1-AS1 was found markedly up-regulated in EC tissues and cell lines. LOXL1-AS1 knockdown displayed evident suppression in cell proliferation, migration and invasion, as well as promotion in cell apoptosis. Moreover, the LOXL1-AS1 induced regulatory effects on EC cells were partially reversed by miR-28-5p inhibitor. Mechanistically, LOXL1-AS1 competitively bond to miR-28-5p, resulting in upregulation of RAP1B. Additionally, in vivo study confirmed the findings discovered in vitro.

CONCLUSIONS

In summary, LOXL1-AS1 exerted oncogenic roles in EC progression by sponging miR-28-5p and thereby upregulating RAP1B. This finding might provide potential targets for EC therapy.

miR-206 inhibits thyroid cancer proliferation and invasion by targeting RAP1B

Thyroid cancer (TC) is one of the primary tumors arisen from endocrine system. The purpose of this study was to investigate the underlying mechanism by which RAP1B (Ras-related protein Rap-1b) modulates microRNA (miR)-206 related effects on TC cells. Expression of miR-206 and RAP1B was analyzed in cells and tissues. miR-206 mimics or inhibitors and RAP1B vector were used in functional experiments to investigate the effects of miR-206 and RAP1B on cell activities including proliferation, migration, and invasion. Luciferase assay was performed to explore the association between miR-206 and RAP1B. The influence of miR-206 on tumorigenesis of TC cells was investigated using an ex vivo model. Our results demonstrated the reduce of miR-206 in TC tissues and cell lines in which RAP1B was increased. Overexpression of miR-206 significantly inhibited the functional capacities of TPC-1 cells including proliferation, invasion, and migration, most likely, through reducing the expression of RAP1B. Xenograft experiment showed that increased miR-206 could effectively inhibit the tumorigenesis of TC cells. Our study showed that miR-206 negatively regulated cell activities of proliferation, invasion, and migration in TC via suppressing RAP1B expression, suggesting that miR-206 exerts a vital role in TC.

Silencing of cadherin-17 enhances apoptosis and inhibits autophagy in colorectal cancer cells

Cadherin-17 (CDH17), a structurally unique member of the non-classical cadherin family, is associated with poor survival, cell proliferation, and metastasis in colorectal cancer. However, the role of CDH17 in the apoptosis and autophagy of colorectal cancer cells remains unclear. Here, we aimed to investigate the effect of CDH17 knockdown on autophagy and apoptosis in colorectal cancer cells. We inhibited CDH17 expression in KM12SM and KM12C colorectal cancer cells by RNA interference and found that silencing of CDH17 significantly inhibited cell viability and increased apoptosis in KM12SM and KM12C cells. In addition, silencing of CDH17 significantly increased the expression of cleaved caspase-3 and Bax and decreased the expression of Bcl-2. Concurrently, silencing of CDH17 significantly inhibited the conversion of LC3-I to LC3-II and decreased the formation of LC3⁺ autophagic vacuoles and the accumulation of acidic vesicular organelles, indicating that autophagy was significantly inhibited in KM12SM and KM12C cells. Additionally, treatment with the autophagy-specific activator rapamycin attenuated apoptosis in CDH17-knockdown cells and as indicated by decreased caspase-3 activity, decreased expression of cleaved caspase-3 and Bax, and increased expression of Bcl-2. In conclusion, CDH17 silencing induced apoptosis and inhibited autophagy in KM12SM and KM12C cells, and this autophagy protected the cells from apoptotic cell death.

Gastrin inhibits gastric cancer progression through activating the ERK-P65-miR23a/27a/24 axis

BACKGROUND

To test the hypothesis that activated extracellular signal-regulated kinase (ERK) regulates P65-miR23a/27a/24 axis in gastric cancer (GC) and the ERK-P65-miR23a/27a/24 axis plays an important role in the development of GC, and to evaluate the role of gastrin in GC progression and ERK-P65-miR23a/27a/24 axis.

METHODS

The component levels of the ERK-P65-miR23a/27a/24 axis in four fresh GC tissues, 101 paraffin-embedded GC tissues and four GC cell lines were determined by Western blotting, immunohistochemistry (IHC) or qRT-PCR. The effects of gastrin on GC were first evaluated by measuring gastrin serum levels in 30 healthy and 70 GC patients and performing a correlation analysis between gastrin levels and survival time in 27 GC patients after eight years of follow-up, then evaluated on GC cell lines, GC cell xenograft models, and patient-derived xenografts (PDX) mouse models. The roles of ERK-P65-miR23a/27a/24 axis in GC progression and in the effects of gastrin on GC were examined.

RESULTS

ERK- P65-miR23a/27a/24 axis was proved to be present in GC cells. The levels of components of ERK-P65-miR23a/27a/24 axis were decreased in GC tissue samples and PGC cells. The decreased levels of components of ERK-P65-miR23a/27a/24 axis were associated with poor prognosis of GC, and ERK-P65-miR23a/27a/24 axis played a suppressive role in GC progression. Low blood gastrin was correlated with poor prognosis of the GC patients and decreased expression of p-ERK and p-P65 in GC tissues. Gastrin inhibited proliferation of poorly-differentiated GC (PGC) cells through activating the ERK-P65-miR23a/27a/24 axis. Gastrin inhibited GC growth and enhanced the suppression of GC by cisplatin in mice or PGC cell culture models through activating the ERK-P65-miR23a/27a/24 axis or its components.

CONCLUSIONS

ERK-P65-miR23a/27a/24 axis is down-regulated, leading to excess GC growth and poor prognosis of GC. Low gastrin promoted excess GC growth and contributed to the poor prognosis of the GC patients by down-regulating ERK-P65-miR23a/27a/24 axis. Gastrin inhibits gastric cancer growth through activating the ERK-P65-miR23a/27a/24 axis.

Delphinidin induced protective autophagy via mTOR pathway suppression and AMPK pathway activation in HER-2 positive breast cancer cells

Background

We have previously demonstrated the anticancer effect of anthocyanins. In this study, we explored the biological activities of delphinidin, the most common of the anthocyanidin monomers, that were related to autophagy in HER-2 positive breast cancer MDA-MB-453 and BT474 cells.

Methods

The effects of various doses of delphinidin on the proliferation and apoptosis of MDA-MB-453 and BT474 cells were analysed. Autophagy was identified as a critical factor that influenced chemotherapy, and the autophagic mechanism in delphinidin-treated cells was investigated. The autophagy inhibitors, 3-MA and BA1, were used to analyse the effects of autophagy inhibition.

Results

Delphinidin inhibited proliferation, promoted apoptosis, and induced autophagy in MDA-MB-453 and BT474 cells in a dose-dependent manner. The inhibition of autophagy enhanced the delphinidin-induced apoptosis and antiproliferative effect in both HER-2 positive breast cancer cells. In addition, delphinidin induced autophagy via suppression of the mTOR signalling pathway and activation of the AMPK signalling pathway in HER-2 positive breast cancer cells.

Conclusions

Collectively, the results showed that delphinidin induced apoptosis and autophagy in HER-2 positive breast cancer cells and that autophagy was induced via the mTOR and AMPK signalling pathways. The suppression of autophagy promoted the anticancer effects of delphinidin.

Honokiol induces autophagy and apoptosis of osteosarcoma through PI3K/Akt/mTOR signaling pathway

Honokiol is the main active constituent of Magnolia officinalis. With effective and long‑term pharmacological functions of being antibacterial, anti‑oxidative, anti‑inflammatory, antitumor, anti‑spasmic, anti‑anxiety and anti‑viral, Honokiol is clinically used in the treatment of acute enteritis and chronic gastritis. The aim of the present study was to observe the possible anti‑effects of honokiol on autophagy and apoptosis of osteosarcoma, and to investigate the role of the PI3K/Akt/mTOR signaling pathway in its anticancer effects. MTT assay was used to evaluate cell proliferation and Annexin V‑fluorescein isothiocyanate/propidium iodide staining flow cytometry was used to analyze the apoptotic rate. The authors identified that honokiol could inhibit cell proliferation and induce the apoptotic rate of osteosarcoma cells. The expression level of Bcl‑2‑like protein 4, caspase‑3 and p53 protein expression were induced and cyclin D1 protein expression was suppressed in osteosarcoma cells by honokiol. Autophagy‑associated LC3II protein expression level was promoted, and PI3K, p‑Akt and p‑mTOR protein expression level was suppressed in osteosarcoma cells by honokiol. The present study demonstrated, to the best of the authors' knowledge, for the first time that honokiol induces autophagy and apoptosis of osteosarcoma cells through the PI3K/Akt/mTOR signaling pathway.

The miRNA Pull Out Assay as a Method to Validate the miR-28-5p Targets Identified in Other Tumor Contexts in Prostate Cancer

miR-28-5p is an intragenic miRNA which is underexpressed in several tumor types showing a tumor suppressor (TS) activity. Routinely, the known miR-28-5p targets are validated in specific tumor contexts but it is unclear whether these targets are also being regulated in other tumor types. To this end, we adopted the miRNA pull out assay to capture the miR-28-5p targets in DU-145 prostate cancer (PCa) cells. Firstly, we demonstrated that miR-28-5p acts as a TS-miRNA in PCa, affecting cell proliferation, survival, and apoptosis. Secondly, we evaluated the enrichment of the 10 validated miR-28-5p targets in the pull out sample. We showed that E2F6, TEX-261, MAPK1, MPL, N4BP1, and RAP1B but not BAG1, OTUB1, MAD2L1, and p21 were significantly enriched, suggesting that not all the miR-28-5p targets are regulated by this miRNA in PCa. We then verified whether the miR-28-5p-interacting targets were regulated by this miRNA. We selected E2F6, the most enriched target in the pull out sample, and demonstrated that miR-28-5p downregulated E2F6 at the protein level suggesting that our approach was effective. In general terms, these findings support the miRNA pull out assay as a useful method to identify context-specific miRNA targets.

Autophagy inhibitor regulates apoptosis and proliferation of synovial fibroblasts through the inhibition of PI3K/AKT pathway in collagen-induced arthritis rat model

BACKGROUND AND OBJECTIVE

Mounting studies have illustrated an important role of autophagy in various diseases, but few studies have reported its contribution to rheumatoid arthritis (RA) and the underlying mechanism was largely unknown. This study aimed to investigate whether autophagy inhibitors could regulate apoptosis and proliferation through PI3K/AKT pathway in RA.

METHODS

RA animal model was established by collagen induction. General observations and degree of joint swelling were observed. Inflammatory response, cell survival related factors and apoptosis were also detected in synovial fibroblasts. In addition, cultured rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) were subjected to TNF-α treatment in vitro, and TNF-α induced cell autophagy, synovial cell proliferation and apoptosis were detected. Moreover, cell cycle and cytokine secretion protein, along with the above parameters, were analyzed.

RESULTS

Results from the animal model showed that autophagy inhibitors attenuated inflammatory reaction and synovial hyperplasia, while promoted synovial fibroblasts apoptosis. Meanwhile, inhibition of autophagy promoted cell apoptosis and reversed cell proliferation in vitro, also blocked cell in the G2/M arrest and reduced the S phase cells. Furthermore, we observed that inhibition of PI3K/AKT pathway reversed TNF-α mediated autophagy and cytokine secretion.

CONCLUSION

autophagy inhibitors could mitigate inflammation response, inhibiting RA-FLS cell proliferation while promoting cell apoptosis by the PI3K/AKT pathway.

Essential amino acid mixtures drive cancer cells to apoptosis through proteasome inhibition and autophagy activation

Cancer cells require both energy and material to survive and duplicate in a competitive environment. Nutrients, such as amino acids (AAs), are not only a caloric source, but can also modulate cell metabolism and modify hormone homeostasis. Our hypothesis is that the environmental messages provided by AAs rule the dynamics of cancer cell life or death, and the alteration of the balance between essential amino acids (EAAs) and non-essential amino acids (NEAAs) (lower and higher than 50%, respectively) present in nutrients may represent a key instrument to alter environment-dependent messages, thus mastering cancer cells destiny. In this study, two AA mixtures, one exclusively consisting of EAAs and the other consisting of 85% EAAs and 15% NEAAs, were tested to explore their effects on the viability of both normal and cancer cell lines and to clarify the molecular mechanisms involved. Both mixtures exerted a cell-dependent anti-proliferative, cytotoxic effect involving the inhibition of proteasome activity and the consequent activation of autophagy and apoptosis. These results, besides further validating the notion of the peculiar interdependence and extensive crosstalk between the ubiquitin-proteasome system (UPS) and autophagy, indicate that variation in the ratio of EAAs and NEAAs can deeply influence cancer cell survival. Consequently, customization of dietary ratios among EAAs and NEAAs by specific AA mixtures may represent a promising anticancer strategy able to selectively induce death of cancer cells through the induction of apoptosis via both UPS inhibition and autophagy activation.