c-Jun N-terminal kinase regulates apoptosis in endometrial cancer cells

Topical metformin accelerates wound healing by promoting collagen synthesis and inhibiting apoptosis in a diabetic wound model

The wound healing process, which is a pathophysiological process that includes various phases, is interrupted in diabetes due to hyperglycemia, and since deterioration occurs in these phases, a normal healing process is not observed. The aim of the current study is to investigate the proliferative and antiapoptotic effects of metformin on wound healing after topical application on diabetic and non-diabetic wounds. For this purpose, we applied metformin topically on the full-thickness excisional wound model we created in diabetic and nondiabetic groups. We investigated the effects of metformin on the apoptotic index by the Terminal deoxynucleotidyl transferase mediated dUTP Nick-End Labeling method and on collagen-I, collagen-III, p53, and c-jun expression levels by quantitative reverse transcription polymerase chain reaction technique in wound biopsy tissues. Our results showed that c-jun and p53 mRNA levels and apoptotic index increased with the effect of diabetes, while collagen synthesis was disrupted. As a result of the study, we showed that metformin increases cellular proliferation and has anti-apoptotic effects by increasing collagen-I/III expression and decreasing p53/c-jun level, especially in diabetic wounds and also in normal wounds. In conclusion, the topical effect of metformin on diabetic wounds reversed the adverse effects caused by diabetes, increasing the wound healing rate and improving the wound repair process.

Oryzalin impairs maternal-fetal interaction during early pregnancy via ROS-mediated P38 MAPK/AKT and OXPHOS downregulation

Oryzalin is a dinitroaniline pesticide for the control of weed growth via suppression of microtubule synthesis. There are studies about the deleterious effects of dinitroaniline pesticides on the reproductive system. Therefore, we attempted to demonstrate the toxic mechanisms of oryzalin on early pregnancy using porcine uterine epithelial cells (pLE) and trophectoderm (pTr) cells. According to our results, the viability and proliferation of pLE and pTr cells were suppressed in response to oryzalin exposure, and cell cycle progression was affected. Additionally, oryzalin induced apoptotic cell death and impaired mitochondrial membrane polarity in pLE and pTr cells. Moreover, we confirmed that oryzalin significantly downregulated adenosine triphosphate (ATP) production via the oxidative phosphorylation system and upregulated reactive oxygen species (ROS) generation in both pLE and pTr cells. The oryzalin-induced ROS generation was mitigated by N-acetylcysteine, a ROS scavenger, and further upregulation of phosphor-P38 MAPK/AKT/P70S6K protein expression was ameliorated in both pLE and pTr cells. We also confirmed that the suppression of migration and proliferation in oryzalin-treated pLE and pTr cells was restored upon oxidative stress mitigation. In summary, we revealed that the cytotoxic mechanisms of oryzalin-induced implantation failure were mediated by ROS-induced intracellular signaling regulation and migratory potential in pLE and pTr cells.

The Prognostic Significance of Anisomycin-Activated Phospho-c-Jun NH2-Terminal Kinase (p-JNK) in Predicting Breast Cancer Patients' Survival Time

This study aims to investigate the prognostic significance of p-JNK in breast cancer patients receiving neoadjuvant chemotherapy (NACT) and analyze the relationship between anisomycin, p-JNK. A total of 104 breast cancer patients had NACT were enrolled in this study. The western blot and immunohistochemistry assays were used to determine the protein expressions of p-JNK in human breast cancer cell lines and patients’ cancer tissues. The chi-square test and Fisher’s exact test were adopted to gauge the associations between breast cancer and clinicopathological variables by p-JNK expression, whereas the univariate and multivariate Cox proportional hazards regression models were used to analyze the prognostic value of p-JNK expression. The Kaplan-Meier plots and the log-rank test were adopted to determine patients’ disease-free survival (DFS) and overall survival (OS). Findings indicated that the p-JNK expression had prognostic significance in univariate and multivariate Cox regression survival analyses. Results of log-rank methods showed that: (1) the mean DFS and OS times in patients with high p-JNK expression were significantly longer than those in patients with low p-JNK expression (χ² = 5.908, P = 0.015 and χ² = 6.593, P = 0.010, respectively). p-JNK expression is a significant prognostic factor that can effectively predict the survival in breast cancer patients receiving NACT. Treatment with the JNK agonist anisomycin can induce apoptosis, lead to increased p-JNK expression and decreased p-STAT3 expression. Moreover, the p-JNK expression was inversely correlated with p-STAT3 expression.

Clinical significance and prospective molecular mechanism of MALAT1 in pancreatic cancer exploration: a comprehensive study based on the GeneChip, GEO, Oncomine, and TCGA databases

Purpose

Long noncoding RNAs (lncRNAs) are known to function as regulators in the development and occurrence of various tumors. MALAT1 is a highly conserved lncRNA and has vital functions in diverse tumors, including pancreatic cancer (PC). However, the underlying molecular regulatory mechanism involved in the occurrence and development of PC remains largely unknown. Thus, it is important to explore MALAT1 in PC and elucidate its function, which might offer a new perspective for clinical diagnosis and therapy.

Methods

First, we used the Gene Expression Omnibus, Oncomine, and The Cancer Genome Atlas databases to determine the clinical diagnostic and prognostic values of MALAT1. We next used our own GeneChip and The Cancer Genome Atlas database to collect the possible target genes of MALAT1 and further utilized a bioinformatics analysis to explore the underlying significant pathways that might be crucial in PC. Finally, we identified several key target genes of MALAT1 and hope to offer references for future research.

Results

We found that the expression of MALAT1 was significantly elevated in patients with PC. A receiver operating characteristics curve analysis showed a moderate diagnostic value (area under the curve =0.75, sensitivity =0.66, specificity =0.72). A total of 224 important overlapping genes were collected, and six hub genes (CCND1, MAPK8, VEGFA, FOS, CDH1, and HSP90AA1) were identified, of which CCND1, MAPK8, and VEGFA, are important genes in PC. Several pathways, including the mTOR signaling pathway, pathways in cancer, and the MAPK signaling pathway, were suggested to be the vital MALAT1 pathways in PC.

Conclusion

MALAT1 is suggested to be a promising diagnostic biomarker in PC. Six hub genes (CCND1, MAPK8, VEGFA, FOS, CDH1, and HSP90AA1), and specifically CCND1, MAPK8, and VEGFA, might be key MALAT1 target genes in PC. Due to their possible clinical significance in PC, several pathways, such as the mTOR signaling pathway, pathways in cancer, and the MAPK signaling pathway, are worthy of further study.

Anisomycin-induced GATA-6 degradation accompanying a decrease of proliferation of colorectal cancer cell

Transcription factor GATA-6 plays a key role in normal cell differentiation of the mesoderm and endoderm. On the other hand, GATA-6 is abnormally overexpressed in many clinical gastrointestinal cancer tissue samples, and accelerates cell proliferation or an anti-apoptotic response in cancerous tissues. We previously showed that activation of the JNK signaling cascade causes proteolysis of GATA-6. In this study, we demonstrated that anisomycin, a JNK activator, stimulates nuclear export of GATA-6 in a colorectal cancer cell line, DLD-1. Concomitantly, anisomycin remarkably inhibits the proliferation of DLD-1 cells via G2/M arrest in a plate culture. However, it did not induce apoptosis under growth arrest conditions. Furthermore, the growth of DLD-1 cells in a spheroid culture was suppressed by anisomycin. Although 5-FU showed only a slight inhibitory effect on 3D spheroid cultures, the same concentration of 5-FU together with a low concentration of anisomycin exhibited strong growth inhibition. These results suggest that the induction of GATA-6 dysfunction may be more effective for chemotherapy for colorectal cancer, although the mechanism underlying the synergistic effect of 5-FU and anisomycin remains unknown.

The phosphatidylinositol 3-kinase/Akt and c-Jun N-terminal kinase signaling in cancer: Alliance or contradiction? (Review)

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway and c-Jun N-terminal kinase (JNK) pathway are responsible for regulating a variety of cellular processes including cell growth, migration, invasion and apoptosis. These two pathways are essential to the development and progression of tumors. The dual roles of JNK signaling in apoptosis and tumor development determine the different interactions between the PI3K/Akt and JNK pathways. Activation of PI3K/Akt signaling can inhibit stress- and cytokine-induced JNK activation through Akt antagonizing and the formation of the JIP1-JNK module, as well as the activities of upstream kinases ASK1, MKK4/7 and MLK. On the other hand, hyperactivation of Akt and JNK is also found in cancers that harbor EGFR overexpression or loss of PTEN. Understanding the activation mechanism of PI3K/Akt and JNK pathways, as well as the interplays between these two pathways in cancer may contribute to the identification of novel therapeutic targets. In the present report, we summarized the current understanding of the PI3K/Akt and JNK signaling networks, as well as their biological roles in cancers. In addition, the interactions and regulatory network between PI3K/Akt and JNK pathways in cancer were discussed.

Focal adhesion signaling and therapy resistance in cancer

Interlocking gene mutations, epigenetic alterations and microenvironmental features perpetuate tumor development, growth, infiltration and spread. Consequently, intrinsic and acquired therapy resistance arises and presents one of the major goals to solve in oncologic research today. Among the myriad of microenvironmental factors impacting on cancer cell resistance, cell adhesion to the extracellular matrix (ECM) has recently been identified as key determinant. Despite the differentiation between cell adhesion-mediated drug resistance (CAMDR) and cell adhesion-mediated radioresistance (CAMRR), the underlying mechanisms share great overlap in integrin and focal adhesion hub signaling and differ further downstream in the complexity of signaling networks between tumor entities. Intriguingly, cell adhesion to ECM is per se also essential for cancer cells similar to their normal counterparts. However, based on the overexpression of focal adhesion hub signaling receptors and proteins and a distinct addiction to particular integrin receptors, targeting of focal adhesion proteins has been shown to potently sensitize cancer cells to different treatment regimes including radiotherapy, chemotherapy and novel molecular therapeutics. In this review, we will give insight into the role of integrins in carcinogenesis, tumor progression and metastasis. Additionally, literature and data about the function of focal adhesion molecules including integrins, integrin-associated proteins and growth factor receptors in tumor cell resistance to radio- and chemotherapy will be elucidated and discussed.

Tethering of the conserved piggyBac transposase fusion protein CSB-PGBD3 to chromosomal AP-1 proteins regulates expression of nearby genes in humans

The CSB-PGBD3 fusion protein arose more than 43 million years ago when a 2.5-kb piggyBac 3 (PGBD3) transposon inserted into intron 5 of the Cockayne syndrome Group B (CSB) gene in the common ancestor of all higher primates. As a result, full-length CSB is now coexpressed with an abundant CSB-PGBD3 fusion protein by alternative splicing of CSB exons 1-5 to the PGBD3 transposase. An internal deletion of the piggyBac transposase ORF also gave rise to 889 dispersed, 140-bp MER85 elements that were mobilized in trans by PGBD3 transposase. The CSB-PGBD3 fusion protein binds MER85s in vitro and induces a strong interferon-like innate antiviral immune response when expressed in CSB-null UVSS1KO cells. To explore the connection between DNA binding and gene expression changes induced by CSB-PGBD3, we investigated the genome-wide DNA binding profile of the fusion protein. CSB-PGBD3 binds to 363 MER85 elements in vivo, but these sites do not correlate with gene expression changes induced by the fusion protein. Instead, CSB-PGBD3 is enriched at AP-1, TEAD1, and CTCF motifs, presumably through protein-protein interactions with the cognate transcription factors; moreover, recruitment of CSB-PGBD3 to AP-1 and TEAD1 motifs correlates with nearby genes regulated by CSB-PGBD3 expression in UVSS1KO cells and downregulated by CSB rescue of mutant CS1AN cells. Consistent with these data, the N-terminal CSB domain of the CSB-PGBD3 fusion protein interacts with the AP-1 transcription factor c-Jun and with RNA polymerase II, and a chimeric CSB-LacI construct containing only the N-terminus of CSB upregulates many of the genes induced by CSB-PGBD3. We conclude that the CSB-PGBD3 fusion protein substantially reshapes the transcriptome in CS patient CS1AN and that continued expression of the CSB-PGBD3 fusion protein in the absence of functional CSB may affect the clinical presentation of CS patients by directly altering the transcriptional program.

Inhibiting the mTOR pathway synergistically enhances cytotoxicity in ovarian cancer cells induced by etoposide through upregulation of c-Jun

PURPOSE

The mTOR pathway is thought to be a central regulator of proliferation and survival of cells. Rapamycin and its analogs are undergoing clinical trials in patients with epithelial ovarian cancer. This study aimed to assess the potential to use rapamycin and anticancer agents in combination for first- and second-line chemotherapy to treat ovarian cancer.

EXPERIMENTAL DESIGN

We used six ovarian serous adenocarcinoma cell lines (KF, KOC-2S, SHIN-3, SK-OV-3, TU-OS-3, and TU-OS-4) in this study. We treated the cells with rapamycin and anticancer agents, then assessed cell viability, apoptosis, and the expression of protein in apoptotic pathways and molecules downstream of the mTOR signaling pathways. We also investigated the effect of these drug combinations on survival in nude mouse xenograft models.

RESULTS

Synergistic effects were observed in five cell lines from the combination of etoposide and rapamycin. However, we observed antagonistic effects when rapamycin was combined with gemcitabine, cisplatin, or paclitaxel on more than two cell lines. Rapamycin dramatically enhanced apoptosis induced by etoposide and the expression of cleaved caspase 9. This effect was associated with upregulation of phosphorylated c-Jun and downregulation of Bcl-xL. The synergistic interaction of rapamycin and etoposide was lower when the c-Jun pathway was suppressed by a c-Jun N-terminal kinase inhibitor (SP600125). Finally, treating nude mice with rapamycin and etoposide significantly prolonged survival in the model mice with ovarian cancer xenografts.

CONCLUSIONS

Chemotherapy with rapamycin and etoposide combined is worth exploring as a treatment modality for women with epithelial ovarian cancer.

Tetrathiomolybdate induces doxorubicin sensitivity in resistant tumor cell lines

OBJECTIVE

Doxorubicin is a potent anti-cancer agent with efficacy against a broad range of tumors, including endometrial cancer. Doxorubicin produces reactive oxygen species (ROS) resulting in cytotoxicity. Tetrathiomolybdate (TM), a copper-chelating agent, is known to target a cellular antioxidant enzyme copper/zinc-superoxide dismutase. This study tests the hypothesis that TM can modulate antioxidants in tumor cells and render doxorubicin resistant tumor cells sensitive to doxorubicin.

METHODS

The anti-cancer activities of doxorubicin and TM, as single agents and in combination, were assessed. Flow cytometric and immunoblot analysis were conducted to investigate the induction of apoptosis and changes in apoptotic signaling pathways.

RESULTS

Doxorubicin-induced growth inhibition was observed in each endometrial cancer cell line (ECC-1, AN3CA, and KLE) tested with cell specificity. ECC-1 and KLE cells were found to have increased resistance to doxorubicin than AN3CA cells. Moreover, doxorubicin mediated apoptosis was greater in the AN3CA cell line than ECC-1 and KLE. The combination of doxorubicin with a sub-cytotoxic level of TM was significantly more effective at inducing apoptosis in doxorubicin resistant cell lines.

CONCLUSION

Our results highlight the therapeutic potential of TM to sensitize tumor cells to doxorubicin for endometrial cancer treatment.

Epigenetic silencing of Stk39 in B-cell lymphoma inhibits apoptosis from genotoxic stress

B-cell lymphomas, the most frequent human immune system malignancies, often contain dysregulated TCL1 oncogene expression. TCL1 transgenic (TCL1-tg) mice develop a spectrum of B-cell malignancies, supporting an oncogenic role for TCL1 in B cells. Our prior global survey of DNA methylation patterns in TCL1-tg B-cell lymphomas identified many lymphoma-specific candidate hypermethylated genes, including Stk39. The Stk39 encoded protein, sterile 20-like-related proline-alanine-rich kinase (SPAK), regulates cell stress responses, and microarray studies identified reduced SPAK expression in metastatic prostate and treatment-resistant breast cancers, suggesting that its loss may have a role in cancer progression. Here we identified DNA hypermethylation and SPAK silencing in TCL1-tg B-cell lymphomas and SPAK silencing without DNA methylation in multiple subtypes of human B-cell lymphomas. SPAK knockdown by shRNA protected B cells from caspase-dependent apoptosis induced by DNA double-strand breaks but not apoptosis in response to osmotic or oxidative cell stressors. Caspase 3 activation by cleavage was impaired with SPAK repression in DNA damaged B cells. Interestingly, c-Jun NH(2)-terminal kinase is potentially activated by SPAK and pharmacological inhibition of c-Jun NH(2)-terminal kinase in SPAK-expressing B cells recapitulated the cell-protective phenotype of SPAK knockdown. Taken together, these data indicate that SPAK loss in B-cell lymphomas promotes increased cell survival with DNA damage and provides a potential mechanism for increased resistance to genotoxic stress in cancer.