Identification of lncRNA and mRNA regulatory networks associated with gastric cancer progression.

Gastric cancer is a tumor type characterized by lymph node metastasis and the invasion of local tissues. There is thus a critical need to clarify the molecular mechanisms governing gastric cancer onset and progression to guide the treatment of this disease. Long non-coding RNAs and mRNA expression profiles associated with early and local advanced gastric cancer were examined through microarray analyses, with GO and KEGG analyses being employed as a means of exploring the functional roles of those long non-coding RNAs and mRNAs that were differentially expressed in gastric cancer. In total, 1005 and 1831 lncRNAs and mRNAs, respectively, were found to be differentially expressed between early and local advanced gastric cancer. GO and KEGG analyses revealed several pathways and processes that were dysregulated, including the RNA transport, ECM-receptor interaction, and mRNA splicing pathways. In co-expression networks, E2F1, E2F4, and STAT2 were identified as key transcriptional regulators of these processes. Moreover, thrombospondin-2 was confirmed as being expressed at high levels in more advanced gastric cancer by both the GEO and TCGA databases. RNA-sequencing analyses of SGC-790 cells transfected to express thrombospondin-2 further revealed this gene to enhance NF-kB and TNF pathway signaling activity. These results offer insight into gastric cancer-related regulatory networks and suggest thrombospondin-2 to be an important oncogene that drives the progression of this deadly cancer type.

Association of mitochondrial homeostasis and dynamic balance with malignant biological behaviors of gastrointestinal cancer.

Mitochondria determine the physiological status of most eukaryotes. Mitochondrial dynamics plays an important role in maintaining mitochondrial homeostasis, and the disorder in mitochondrial dynamics could affect cellular energy metabolism leading to tumorigenesis. In recent years, disrupted mitochondrial dynamics has been found to influence the biological behaviors of gastrointestinal cancer with the potential to be a novel target for its individualized therapy. This review systematically introduced the role of mitochondrial dynamics in maintaining mitochondrial homeostasis, and further elaborated the effects of disrupted mitochondrial dynamics on the cellular biological behaviors of gastrointestinal cancer as well as its association with cancer progression. We aim to provide clues for elucidating the etiology and pathogenesis of gastrointestinal cancer from the perspective of mitochondrial homeostasis and disorder.

3D printed collagen/silk fibroin scaffolds carrying the secretome of human umbilical mesenchymal stem cells ameliorated neurological dysfunction after spinal cord injury in rats.

Although implantation of biomaterials carrying mesenchymal stem cells (MSCs) is considered as a promising strategy for ameliorating neural function after spinal cord injury (SCI), there are still some challenges including poor cell survival rate, tumorigenicity and ethics concerns. The performance of the secretome derived from MSCs was more stable, and its clinical transformation was more operable. Cytokine antibody array demonstrated that the secretome of MSCs contained 79 proteins among the 174 proteins analyzed. Three-dimensional (3D) printed collagen/silk fibroin scaffolds carrying MSCs secretome improved hindlimb locomotor function according to the Basso-Beattie-Bresnahan scores, the inclined-grid climbing test and electrophysiological analysis. Parallel with locomotor function recovery, 3D printed collagen/silk fibroin scaffolds carrying MSCs secretome could further facilitate nerve fiber regeneration, enhance remyelination and accelerate the establishment of synaptic connections at the injury site compared to 3D printed collagen/silk fibroin scaffolds alone group according to magnetic resonance imaging, diffusion tensor imaging, hematoxylin and eosin staining, Bielschowsky's silver staining, immunofluorescence staining and transmission electron microscopy. These results indicated the implantation of 3D printed collagen/silk fibroin scaffolds carrying MSCs secretome might be a potential treatment for SCI.

[Absence of BAX differentially affects astrocyte density in the mouse cortex and hippocampus].

Astrocytes are a heterogenous group of macroglia present in all regions of the brain and play critical roles in many aspects of brain development, function and disease. Previous studies suggest that the B-cell lymphoma-2 associated X protein (BAX)-dependent apoptosis plays essential roles in regulating neuronal number and achieving optimal excitation/inhibition ratio. The aim of the present paper was to study whether BAX regulates astrocyte distribution in a region-specific manner. Immunofluorescence staining of SOX9 was used to analyze and compare astrocyte density in primary somatosensory cortex, motor cortex, retrosplenial cortex and hippocampus in heterozygous and homozygous BAX knockout mice at age of six weeks when cortical development has finished and glia development has reached a relatively steady state. The results showed that astrocyte density varied significantly among different cortical subdivisions and between cortex and hippocampus. In contrast to the significant increase in GABAergic interneurons, the overall and region-specific astrocyte density remained unchanged in the cortex when BAX was absent. Interestingly, a significant reduction of astrocyte density was observed in the hippocampus of BAX knockout mice. These data suggest that BAX differentially regulates neurons and astrocytes in cortex as well as astrocytes in different brain regions during development. This study provided important information about the regional heterogeneity of astrocyte distribution and the potential contribution of BAX gene during development.

Serum level of interleukin-35 as a potential prognostic factor for gastric cancer.

AIMS: Interleukin-35 (IL-35), a novel anti-inflammatory cytokine, has recently been implicated in tumor development, progression, and survival. However, the relationship between serum IL-35 levels and gastric cancer (GC) is inconclusive. Here, we performed this study to clarify the role of serum level of IL-35 in GC patients. METHODS: We enrolled 180 GC patients and 170 healthy controls and used enzyme-linked immunosorbent assay to detect serum IL-35 levels. The clinical relevance between IL-35 and clinical pathology parameters was assessed. Univariate and multivariate logistic regressions were used to determine the feasibility of IL-35 as a clinical biomarker. RESULTS: We observed that serum IL-35 levels were significantly higher in GC patients (17.559 ± 13.266 pg/mL) than in healthy controls (8.077 ± 3.801 pg/mL, P < .001). High serum IL-35 levels were significantly associated with clinical stage (P = .048) and Helicobacter pylori (HP) infection (P < .001). The Kaplan-Meier survival analysis indicated that patients in the high-IL-35 group had poor overall survival (OS) and progression-free survival (PFS) (median OS: 26.0 vs 36.0 months, P < .001; median PFS: 18.0 vs.26.0 months, P = .044). Multivariate analyses demonstrated that serum IL-35 was an independent prognostic factor for GC (OS: hazard ratio [HR] = 1.031 [95% CI, 1.017-1.045], P < .001; PFS: HR = 1.029 [95% CI, 1.015-1.043], P < .001). CONCLUSIONS: High serum IL-35 levels are associated with poor disease prognosis in GC patients, and it may be become a new and promising biomarker for prognosis of gastric cancer.

Integrated Profiling Revealed Potential Regulatory Networks Among Long Noncoding RNAs and mRNAs in Mucosal Gastric Cancer.

Gastric cancer is one of the most commonly occurring cancers worldwide. Investigation of long noncoding RNAs is of increasing interest, particularly in relation to their contribution to progression and prognosis of gastric cancers; however, insufficient studies been performed investigating the part of long noncoding RNAs play in gastric cancer carcinogenesis. Patterns of dysregulated long noncoding RNA and messenger RNA between mucosa gastric cancer and adjacent normal tissues were identified using long noncoding RNAs microarray analysis. Quantitative real-time polymerase chain reaction was conducted as a means to verify the obtained data. Both Gene Ontology and Kyoto Encyclopedia of Genes and Genomes  (KEGG) pathway analyses were subsequently used to investigate the function of dysregulated long noncoding RNAs and messenger RNAs. Cis and trans action was used to predict the possible targets of long noncoding RNAs, and a coexpression network was created to simulate the complex intergenic interactions. Ninety-five dysregulated long noncoding RNAs and 123 messenger RNAs were identified, and quantitative real-time polymerase chain reaction was used to validate 6 filtered long noncoding RNAs. Gene Ontology and KEGG pathway analyses identified several remarkably biological processes and signaling pathways, including spliceosome, RNA transport, and ubiquitin-mediated proteolysis. The transcriptional factors MYC, GABPA, and E2F1 were found to play a central function in the long noncoding RNAs process, as indicated by the coexpression network. This study revealed the dysregulated long noncoding RNA profiles of mucosal gastric cancer. The results shed light on the biological function of long noncoding RNAs in gastric cancer pathogenesis. This provides useful information for exploring potential early screening biomarkers in gastric cancer.

Deficiency of Macf1 in osterix expressing cells decreases bone formation by Bmp2/Smad/Runx2 pathway.

Microtubule actin cross-linking factor 1 (Macf1) is a spectraplakin family member known to regulate cytoskeletal dynamics, cell migration, neuronal growth and cell signal transduction. We previously demonstrated that knockdown of Macf1 inhibited the differentiation of MC3T3-E1 cell line. However, whether Macf1 could regulate bone formation in vivo is unclear. To study the function and mechanism of Macf1 in bone formation and osteogenic differentiation, we established osteoblast-specific Osterix (Osx) promoter-driven Macf1 conditional knockout mice (Macf1f/f Osx-Cre). The Macf1f/f Osx-Cre mice displayed delayed ossification and decreased bone mass. Morphological and mechanical studies showed deteriorated trabecular microarchitecture and impaired biomechanical strength of femur in Macf1f/f Osx-Cre mice. In addition, the differentiation of primary osteoblasts isolated from calvaria was inhibited in Macf1f/f Osx-Cre mice. Deficiency of Macf1 in primary osteoblasts inhibited the expression of osteogenic marker genes (Col1, Runx2 and Alp) and the number of mineralized nodules. Furthermore, deficiency of Macf1 attenuated Bmp2/Smad/Runx2 signalling in primary osteoblasts of Macf1f/f Osx-Cre mice. Together, these results indicated that Macf1 plays a significant role in bone formation and osteoblast differentiation by regulating Bmp2/Smad/Runx2 pathway, suggesting that Macf1 might be a therapeutic target for bone disease.

MicroRNA-31 triggers G2/M cell cycle arrest, enhances the chemosensitivity and inhibits migration and invasion of human gastric cancer cells by downregulating the expression of zeste homolog 2 (ZH2).

Gastric cancer is the second most leading cause of cancer related mortality across the world over. Although the incidence of GC has declined to some extent but it is still the fourth highly diagnosed cancer across the world. GC generally remains undiagnosed till advanced stages due to unavailability of biomarkers and when diagnosed it becomes difficult to manage due to the lack of therapeutic targets and efficient chemotherapy. There are concrete evidences suggesting that miRNAs may prove important therapeutic targets for the treatment of devastating diseases such as cancer. The study was designed to investigate the tumor suppressive role of miR-31 via regulation of zeste homolog 2 (ZH2). It was found that miR-31 is significantly downregulated in GC cell lines. Overexpression of miR-31 causes significant (P < 0.05) decrease in the viability and colony formation via initiation of G2/M cell cycle arrest of the AGS cancer cells. Moreover, miR-31 overexpression also enhanced the chemosensitivity of miR-31 to the anticancer drug 5-fluorouracil. In silico analysis together with dual luciferase reporter assay indicated zeste homolog 2 (ZH2) to be the potential target of miR-31 in AGS cells. Investigation of ZH2 expression in GC cell lines showed it to be significantly (P < 0.05) upregulated. Nonetheless, overexpression of miR-31 in AGS cells resulted in the suppression of ZH2 expression. Additionally, silencing of ZH2 in the AGS cells also caused inhibition of AGS cell proliferation and colony formation via G2/M arrest. Moreover, overexpression of ZH2 could at least partially reverse the tumor suppressive effects of miR-31 indicating direct involvement of ZH2 in the miR-31 mediated inhibitory effects on AGS cell proliferation. Finally, miR-31 overexpression caused significant (P < 0.05) inhibition of the migration and invasion of the AGS gastric cancer cells. The overexpression of miR-31 also caused downregulation of mesenchymal markers (Vimentin and N-cadherin) and upregulation of epithelial marker (E-cadherin) protein expression was in AGS cells. It is therefore concluded that miR-31 acts as a tumor suppressor and may prove essential in the treatment of GC.

miR-557 inhibits the proliferation and invasion of pancreatic cancer cells by targeting EGFR.

Deregulation of microRNA has been suggested as a critical event in pancreatic cancer development and progression. Thus far, very little is known about the role of miR-557; therefore, the goal of this study was to investigate the potential role of miR-557 in pancreatic cancer. In the present study, we discovered that miR-557 expression was lowered in cancerous pancreatic tissue samples relative to non-cancerous adjacent controls, and when miR-557 was overexpressed we found that this promoted the apoptotic death of pancreatic cancer cells, suppressing their proliferation, invasion, and migration. Using western blotting and luciferase reporter assays, we further found evidence that this miRNA may directly suppress expression of the epidermal growth factor receptor via suppressing its translation through 3'-UTR binding. When EGFR was overexpressed in our pancreatic cancer cells, this was sufficient to reverse the effects of miR-557 inhibition. In summary, miR-557 acts as a tumor suppressor in pancreatic cancer cells, impairing their ability to grow and invade surrounding tissues due at least in part to EGFR inhibition. Harnessing this targeting of EGFR via this miRNA may therefore be a viable strategy useful for patient suffering from this deadly disease.

Clinicopathological significance of cytoplasmic transducer of ErbB2. 1 expression in gastric cancer.

The aim of the present study was to investigate the expression of transducer of ErbB2. 1 (TOB1) in gastric carcinoma and to clarify the association between TOB1 expression and the clinical significance of this expression in patients with gastric carcinoma. Western blot analysis was performed to confirm the expression of TOB1 in gastric cancer. Immunohistochemistry (IHC) was performed on a tissue microarray containing 90 pairs of primary gastric cancer and adjacent normal tissue samples. TOB1 expression was evaluated separately with cytoplasmic and nuclear staining. Western blot analysis revealed significantly lower expression levels of TOB1 in gastric cancer tissues than those in adjacent normal tissues in 91.7% of cases. This was confirmed by IHC, which revealed decreased cytoplasmic TOB1 expression in cancer tissues compared with those of normal tissue samples in 84.4% of cases. The IHC data also revealed low cytoplasmic expression of TOB1 in 67.8% of human gastric cancer samples. Nuclear TOB1 expression exhibited no significant association with specific pathological features. However, a significant association was identified between cytoplasmic expression levels of TOB1 and clinicopathological characteristics, including the depth of invasion (P=0.017), differentiation grade (P=0.034) and tumor-node-metastasis stage (P<0.000). In conclusion, cytoplasmic TOB1 expression was suggested to be significant in angiogenesis and cell differentiation in gastric cancer tissues and may be used as a potential prognostic marker.

Descending colo-colonic intussusception secondary to signet ring cell carcinoma: A case report.

The incidence of intussusception is low in adults, particularly in the descending colon, due to the anatomical attachment of the descending colon to the retroperitoneum. Signet ring cell histology represents ~1% of colon adenocarcinomas and is associated with young patients and a poor clinical outcome. The present study describes a case of descending colo-colonic intussusception caused by signet ring cell carcinoma in a 27-year-old male. The patient presented with a history of intermittent left upper-quadrant abdominal pain for more than six months without any evident etiology. A computed tomography scan of the abdomen revealed left-sided colo-colonic intussusception. Upon laparotomy, a left hemicolectomy was performed according to intraoperative frozen-section pathology. Post-operative pathological evaluation revealed signet ring cell carcinoma invasion of the serosa, and 31.8% (7/22) of the regional lymph nodes were positive for cancerous cells. The post-operative course was uneventful and the patient was discharged on the tenth post-operative day.

Anti-miR-362-3p Inhibits Migration and Invasion of Human Gastric Cancer Cells by Its Target CD82.

AIM: This study was to investigate the effects and mechanisms of miR-362-3p on regulation of gastric cancer (GC) cell metastasis potential. METHODS: We detected miR-362-3p level in GC and adjacent normal tissues and investigated the relationship with clinicopathological factors. Next, we analyzed the level of miR-362-3p expression and CD82 in different differentiated GC cells compared with a normal gastric mucosa cell by RT-PCR and Western blot. Dual-luciferase reporter assay and Western blot confirmed a direct interaction between miR-362-3p and CD82 3'UTR. After miR-362-3p and CD82 were silenced in GC cells, we compared the transfected GC cells migration and invasion capacity by transwell assay. In addition, we detected the effects on cells angiogenesis by tube formation assay. Western blot was used to detect the impact of CD82 and miR-362-3p on epithelial-to-mesenchymal transition markers in treated GC cells. RESULTS: Level of miR-362-3p expression was much higher in GC cells than in normal gastric mucosa cell, and miR-362-3p expression negatively correlated with CD82 mRNA expression in these cell lines. Furthermore, miR-362-3p expression induced [corrected] GC cell metastasis capacity by suppression of CD82 expression. Level of miR-362-3p may mediate E-cadherin, N-cadherin, and vimentin expression in GC cells. CONCLUSION: This study illuminated that downregulation of miR-362-3p along with the upregulation of CD82 in GC cells resulted in the inhibition of GC migration and invasion. Thus, our results suggested that miR-362-3p or CD82 can be exploited as a new potential target for control of GC in the future.

Clinical implication of TMPRSS4 expression in human gallbladder cancer.

Altered expression of transmembrane protease/serine 4 (TMPRSS4) is observed in various types of human cancers. However, the clinical significance of TMPRSS4 expression in gallbladder cancer (GBC) remains largely unknown. The present study aims to explore the clinicopathological significance and prognostic value of TMPRSS4 in GBC. The levels of TMPRSS4 mRNA and protein in GBC tissues and adjacent noncancerous tissues were evaluated by quantitative reverse-transcriptase polymerase chain reaction and immunohistochemistry. To investigate the correlations between TMPRSS4 and the clinicopathological features of GBC, the expression of TMPRSS4 in 97 patients with GBC were detected by immunohistochemistry. The correlation of TMPRSS4 expression with patients' survival rate was assessed by Kaplan-Meier and Cox regression. Our results showed that the expression levels of TMPRSS4 mRNA and protein in GBC tissues were both significantly higher than those in adjacent noncancerous tissues. Immunohistochemical staining revealed that high TMPRSS4 expression was closely correlated with tumor size (P=0.032), histological grade (P=0.002), pathologic T stage (P=0.005), clinical stage (P=0.013), and lymph node metastasis (P=0.003). Moreover, the results of Kaplan-Meier analysis indicated that a high expression level of TMPRSS4 resulted in a significantly poor prognosis of GBC patients. Multivariate analysis showed that the status of TMPRSS4 expression was an independent prognostic factor for GBC patients. Our results showed that TMPRSS4 plays a key role in GBC and therefore may provide an opportunity for developing a novel therapeutic target as well as a prognostic marker in GBC.

MicroRNA-451 regulates AMPK/mTORC1 signaling and fascin1 expression in HT-29 colorectal cancer.

The earlier studies have shown that Fascin1 (FSCN1), the actin bundling protein, is over-expressed in colorectal cancers, and is associated with cancer cell progression. Here, we aimed to understand the molecular mechanisms regulating FSCN1 expression by focusing on mammalian target of rapamycin (mTOR) signaling and its regulator microRNA-451. We found that microRNA-451 was over-expressed in multiple colorectal cancer tissues, and its expression was correlated with mTOR complex 1 (mTORC1) activity and FSCN1 expression. In cultured colorectal cancer HT-29 cells, knockdown of FSCN1 by RNAi inhibited cell migration and proliferation. Activation of mTORC1 was required for FSCN1 expression, HT-29 cell migration and proliferation, as RAD001 and rapamycin, two mTORC1 inhibitors, suppressed FSCN1 expression, HT-29 cell migration and proliferation. Meanwhile, forced activation of AMP-activated protein kinase (AMPK), the negative regulator of mTORC1, by its activators or by the genetic mutation, inhibited mTORC1 activation, FSCN1 expression, cell migration and proliferation. In HT-29 cells, we found that over-expression of microRNA-451 inhibited AMPK activation, causing mTORC1 over-activation and FSCN1 up-regulation, cells were with high migration ability and proliferation rate. Significantly, these effects by microRNA-451 were largely inhibited by mTORC1 inhibitors or the AMPK activator AICAR. On the other hand, knockdown of miRNA-451 by the treatment of HT-29 cells with miRNA-451 antagomir inhibited mTORC1 activation and FSCN1 expression. The proliferation and migration of HT-29 cells after miRNA-45 knockdown were also inhibited. Our results suggested that the over-expressed microRNA-451 in colon cancer cells might inhibit AMPK to activate mTORC1, which mediates FSCN1 expression and cancer cell progression.

Stimulatory effects of sorafenib on human non­small cell lung cancer cells in vitro by regulating MAPK/ERK activation.

Sorafenib is an inhibitor of a number of intracellular signaling kinases with antiproliferative, anti­angiogenic and pro­apoptotic effects in tumor cells. Sorafenib has been used in the therapy of advanced renal cell carcinoma. In the present study, using two human non­small cell lung cancer (NSCLC)cell lines, A549 and NCI­H1975, the effects of sorafenib on proliferation, apoptosis and intracellular signaling were systematically characterized. The results revealed that at a low concentration (5 µM) and early time point (6 h), sorafenib is capable of significantly stimulating proliferation of A549 cells, but not NCI­H1975 cells. In addition, the comparison of the two cell lines revealed different cell cycle redistribution and apoptotic susceptibility to sorafenib at this concentration and time point. Western blot analysis revealed that sorafenib upregulated the expression of cyclin D1 and cyclin­dependent kinase 2 and downregulated the expression of BAX at this specific point. Furthermore, sorafenib was confirmed to regulate the expression of cyclin D1 and apoptosis­associated proteins through the regulation of extracellular signal­regulated kinase 1/2 phosphorylation in A549 cells. These findings suggest that, although sorafenib has the potential for use in the treatment of renal cell carcinoma, this compound may also activate NSCLC cells at a specific time point.

Cyclopamine increases the radiosensitivity of human pancreatic cancer cells by regulating the DNA repair signal pathway through an epidermal growth factor receptor­dependent pathway.

Pancreatic cancer is an aggressive malignancy with a characteristic metastatic course of disease and resistance to conventional radiotherapy. As a result, the continual development of novel therapeutic agents is required to improve the current situation. In the present study, the effect of the hedgehog pathway inhibitor, cyclopamine, on cellular radiosensitivity was determined in K­RASwt Colo­357 and K­RASmt SW­1990 human pancreatic cancer cell lines using the clonogenic survival assay. Apoptosis and cell cycle distribution were detected using flow cytometry assay. Following irradiation (30 mins), residual double­strand breaks were quantified by identification of γ­H2AX foci of micronuclei and radiation­induced γ­H2AX, p­ATM, DNA­PKcs and Ku70 expression was analyzed using western blot analysis. The epidermal growth factor (EGF) and EGF receptor (EGFR) inhibitor, gefitinib, were utilized to determine the related mechanisms. The results revealed that cyclopamine treatment significantly reduced cell clonogenic survival but failed to induce apoptosis and radiation­induced G2 arrest. Flow cytometry revealed that cyclopamine treatment enhanced γ­H2AX foci in Colo­357 and SW­1990 cells exposed to irradiation. In addition, radiation­induced p­ATM, DNA­PKcs and Ku70 were all inhibited. EGF also rescued pancreatic cancer cells from cyclopamine­induced H2AX phosphorylation following irradiation. Thus, cyclopamine enhanced the radiosensitivity of human pancreatic cancer cells, in part, through an EGFR­dependent pathway, indicating a rational approach in combination with radiotherapy.

Effects of microRNA-106 on proliferation of gastric cancer cell through regulating p21 and E2F5.

OBJECTIVE: To investigate the effects of miR-106b on malignant characteristics of gastric cancer cells, and explore possible mechanisms. METHODS: Expression of miR-106b, p21 and E2F was determined by real-time PCR. Transfection with miR-106b mimics was conducted, and gastric cancer cells with miR-106b overexpression were obtained. Cells transfected with mimic mutants and those without transfection served as negative and blank controls, respectively. Flow cytometry and transwell assays were adopted to detect the effects of miR-106b overexpression on cell cycle, migration and invasion of gastric cancer cells. RESULTS: . The expression of miR- 106b in gastric cancer cells was significantly higher than that in normal gastric mucosa cells. Furthermore, the expression level of miR-106b rose according to the degree of malignacy among the three GC cell strains (MKN- 45 > SGC-7901 > MKN-28). Overexpression of miR-106b shortened the G0/G1 phase and accelerated cell cycle progression, while reducing p21 and E2F5, without any significant effects on the capacity for migration and invasion of gastric cancer cells. CONCLUSIONS: miR-106b may promote cell cycling of gastric cancer cells through regulation of p21 and E2F5 target gene expression.

Activation of AMP-activated protein kinase (AMPK) mediates plumbagin-induced apoptosis and growth inhibition in cultured human colon cancer cells.

Here we report that activation of AMP-activated protein kinase (AMPK) mediates plumbagin-induced apoptosis and growth inhibition in both primary cultured human colon cancer cells and cell lines. Knocking-down of AMPKα by the target shRNA significantly inhibits plumbagin-induced cytotoxicity in cultured colon cancer cells, while forced activation of AMPK by introducing a constitutively active AMPK (CA-AMPK), or by the AMPK activator, inhibits HT-29 colon cancer cell growth. Our Western-blots and immunoprecipitation (IP) results demonstrate that plumbagin induces AMPK/Apoptosis signal regulating kinase 1 (ASK1)/TNF receptor-associated factor 2 (TRAF2) association to activate pro-apoptotic c-Jun N-terminal kinases (JNK)-p53 signal axis. Further, after plumbagin treatment, activated AMPK directly phosphorylates Raptor to inhibit mTOR complex 1 (mTORC1) activation and Bcl-2 expression in colon cancer cells. Finally, we found that exogenously-added short-chain ceramide (C6) enhances plumbagin-induced AMPK activation and facilitates cell apoptosis and growth inhibition. Our results suggest that AMPK might be the key mediator of plumbagin's anti-tumor activity.

Overexpression of high mobility group protein B1 correlates with the proliferation and metastasis of lung adenocarcinoma cells.

High mobility group protein B1 (HMGB1) plays an important role in a number of clinical conditions, such as autoimmunity, cardiovascular disease and cancer. Evidence suggests that HMGB1 is critical in the development and progression of numerous types of tumor. However, the underlying molecular mechanisms for the HMGB1-mediated progression and metastasis of lung cancer have not yet been elucidated. In this study, we investigated the role of HMGB1 in lung adenocarcinoma and the mechanisms by which it contributes to carcinogenesis and metastasis. We demonstrated that there was an increase in the expression of HMGB1 in primary cancer tissues compared to the matched adjacent non-cancerous tissues. The expression levels of TOB1 in the normal human bronchial epithelial (HBE) cell line and 10 lung cancer cell lines were determined by reverse transcription-PCR (RT-PCR). The results revealed that HMGB1 expression increased in 8 cell lines compared with the HBE cell line. The A549 and NCI-H1975 cells were transfected with HMGB1 recombinant plasmid. We discovered that the overexpression of HMGB1 promoted cell growth and metastasis in the 2 cell lines. Further investigation revealed that exogenously expressed HMGB1 enhanced the activation of p38 and Erk1/2, in addition to the expression of nuclear factor (NF)-κB. We propose that HMGB1 functions as a tumor promoter and that it regulates the proliferation and invasion of lung cancer cells by modulating the activation of the Erk1/2 and p38 mitogen-activated protein kinase (MAPK) signaling pathways.