u-0126 and Carcinogenesis

Long non-coding RNAs (lncRNAs) participate in cancer cell tumorigenesis, cell cycle control, migration, proliferation, apoptosis, metastasis and drug resistance. The BRAF-activated non-coding RNA (BANCR) functions as both an oncogene and a tumor suppressor. Here, we investigated BANCR's role in papillary thyroid carcinoma (PTC) by assessing BANCR levels in PTC and matched normal thyroid epithelial tissues from 92 patients using qRT-PCR. We also used lentiviral vectors to establish PTC cell lines to investigate the effects of BANCR overexpression on cancer cell proliferation, apoptosis, migration and invasion. Our results indicate BANCR levels are lower in PTC tumor tissues than control tissues. Decreased BANCR levels correlate with tumor size, the presence of multifocal lesions and advanced PTC stage. BANCR overexpression reduced PTC cell proliferation and promoted apoptosis, which inhibited metastasis. It also inactivated ERK1/2 and p38, and this effect was enhanced by treatment with the MEK inhibitor U0126. Finally, BANCR overexpression dramatically inhibited tumor growth from PTC cells in xenograft mouse models. These results suggest BANCR inhibits tumorigenesis in PTC and that BANCR levels may be used as a novel prognostic marker.

Topics: Adult; Animals; Apoptosis; Biomarkers, Tumor; Butadienes; Carcinogenesis; Carcinoma, Papillary; Cell Line, Tumor; Cell Movement; Cell Proliferation; Enzyme Inhibitors; Female; Flow Cytometry; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Humans; Immunohistochemistry; Male; MAP Kinase Signaling System; Mice; Mice, Nude; Middle Aged; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinase Kinases; Neoplasm Invasiveness; Neoplasm Staging; Nitriles; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins B-raf; RNA, Long Noncoding; Thyroid Cancer, Papillary; Thyroid Gland; Thyroid Neoplasms; Xenograft Model Antitumor Assays

The identification of signaling pathways that affect the cancer stem-like phenotype may provide insights into therapeutic targets for combating embryonal rhabdomyosarcoma. The aim of this study was to investigate the role of the MEK/ERK pathway in controlling the cancer stem-like phenotype using a model of rhabdospheres derived from the embryonal rhabdomyosarcoma cell line (RD).. Rhabdospheres enriched in cancer stem like cells were obtained growing RD cells in non adherent condition in stem cell medium. Stem cell markers were evaluated by FACS analysis and immunoblotting. ERK1/2, myogenic markers, proteins of DNA repair and bone marrow X-linked kinase (BMX) expression were evaluated by immunoblotting analysis. Radiation was delivered using an x-6 MV photon linear accelerator. Xenografts were obtained in NOD/SCID mice by subcutaneously injection of rhabdosphere cells or cells pretreated with U0126 in stem cell medium.. MEK/ERK inhibitor U0126 dramatically prevented rhabdosphere formation and down-regulated stem cell markers CD133, CXCR4 and Nanog expression, but enhanced ALDH, MAPK phospho-active p38 and differentiative myogenic markers. By contrast, MAPK p38 inhibition accelerated rhabdosphere formation and enhanced phospho-active ERK1/2 and Nanog expression. RD cells, chronically treated with U0126 and then xeno-transplanted in NOD/SCID mice, delayed tumor development and reduced tumor mass when compared with tumor induced by rhabdosphere cells. U0126 intraperitoneal administration to mice bearing rhabdosphere-derived tumors inhibited tumor growth . The MEK/ERK pathway role in rhabdosphere radiosensitivity was investigated in vitro. Disassembly of rhabdospheres was induced by both radiation or U0126, and further enhanced by combined treatment. In U0126-treated rhabdospheres, the expression of the stem cell markers CD133 and CXCR4 decreased and dropped even more markedly following combined treatment. The expression of BMX, a negative regulator of apoptosis, also decreased following combined treatment, which suggests an increase in radiosensitivity of rhabdosphere cells.. Our results indicate that the MEK/ERK pathway plays a prominent role in maintaining the stem-like phenotype of RD cells, their survival and their innate radioresistance. Thus, therapeutic strategies that target cancer stem cells, which are resistant to traditional cancer therapies, may benefit from MEK/ERK inhibition combined with traditional radiotherapy, thereby providing a promising therapy for embryonal rhabdomyosarcoma.

Topics: Animals; Apoptosis; Butadienes; Carcinogenesis; Cell Line, Tumor; MAP Kinase Signaling System; Mice, Inbred NOD; Mice, SCID; Neoplastic Stem Cells; Nitriles; p38 Mitogen-Activated Protein Kinases; Phenotype; Protein Kinase Inhibitors; Radiation Tolerance; Rhabdomyosarcoma, Embryonal; Spheroids, Cellular; Xenograft Model Antitumor Assays

ADP-ribosylation factor 1 (ARF1) is a crucial regulator in vesicle-mediated membrane trafficking and involved in the activation of signaling molecules. However, virtually nothing is known about its function in prostate cancer. Here we have demonstrated that ARF1 expression is significantly elevated in prostate cancer cells and human tissues and that the expression levels of ARF1 correlate with the activation of mitogen-activated protein kinases (MAPK) ERK1/2. Furthermore, we have shown that overexpression and knockdown of ARF1 produce opposing effects on prostate cancer cell proliferation, anchorage-independent growth and tumor growth in mouse xenograft models and that ARF1-mediated cell proliferation can be abolished by the Raf1 inhibitor GW5074 and the MEK inhibitors U0126 and PD98059. Moreover, inhibition of ARF1 activation achieved by mutating Thr48 abolishes ARF1's abilities to activate the ERK1/2 and to promote cell proliferation. These data demonstrate that the aberrant MAPK signaling in prostate cancer is, at least in part, under the control of ARF1 and that, similar to Ras, ARF1 is a critical regulator in prostate cancer progression. These data also suggest that ARF1 may represent a key molecular target for prostate cancer therapeutics and diagnosis.

Topics: ADP-Ribosylation Factor 1; Animals; Butadienes; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Disease Progression; Flavonoids; Gene Expression Regulation, Neoplastic; Humans; Male; MAP Kinase Kinase 4; MAP Kinase Signaling System; Mice; Mice, SCID; Mutation; Nitriles; p38 Mitogen-Activated Protein Kinases; Prostatic Neoplasms

Septins are a novel class of GTP-binding cytoskeletal proteins evolutionarily conserved from yeast to mammals and have now been found to play a contributing role in a broad range of tumor types. However, their functional importance in breast cancer remains largely unclear. Here, we demonstrated that pharmaceutical inhibition of global septin dynamics would greatly suppress proliferation, migration and invasiveness in breast cancer cell lines. We then examined the expression and subcellular distribution of the selected septins SEPT2 and SEPT7 in breast cancer cells, revealing a rather variable localization of the two proteins with cell cycle progression. To determine the role of both septins in mediating malignant behavior of cancer cells, we used RNA silencing to specifically deplete endogenous SEPT2 or SEPT7 in highly invasive breast cancer cell line MDA-MB-231. Our findings showed that SEPT2/7 depletion had virtually identical inhibitory effects on cellular proliferation, apoptosis, migration and invasion. Moreover, the opposite performance in migration and invasion was observed after enforced expression of SEPT2/7 in the same cell line. We further demonstrated MEK/ERK activation, but not other MAPKs and AKT, was positively correlated with the protein levels of SEPT2 and SEPT7. Additionally, in SEPT2/7-overexpressing cells, the MEK specific inhibitor U0126 was able to correct the high active status of MEK/ERK while normalizing the increased invasive behaviors of these cells. Taken together, these results strongly suggest that SEPT2 and SEPT7 are involved in breast carcinogenesis and may serve as valuable therapeutic targets for breast cancer.

Topics: Apoptosis; Breast Neoplasms; Butadienes; Carcinogenesis; Cell Cycle; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Cell Proliferation; Enzyme Inhibitors; Female; Gene Knockdown Techniques; Human Umbilical Vein Endothelial Cells; Humans; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Microscopy, Fluorescence; Neoplasm Invasiveness; Nitriles; Phenylurea Compounds; Proto-Oncogene Proteins c-akt; Pyridines; RNA Interference; RNA, Small Interfering; Septins

Ultraviolet B (UVB) radiation from the sun may lead to photocarcinogenesis of the skin. Sunscreens were used to protect the skin by reducing UVB irradiance, but sunscreen use did not reduce sunburn episodes. It was shown that UVB-induced erythema depends on surface exposure but not irradiance of UVB. We previously showed that irradiance plays a critical role in UVB-induced cell differentiation. This study investigated the impact of irradiance on UVB-induced photocarcinogenesis. For hairless mice receiving equivalent exposure of UVB radiation, the low irradiance (LI) UVB treated mice showed more rapid tumor development, larger tumor burden, and more keratinocytes harboring mutant p53 in the epidermis as compared to their high irradiance (HI) UVB treated counterpart. Mechanistically, using cell models, we demonstrated that LI UVB radiation allowed more keratinocytes harboring DNA damages to enter cell cycle via ERK-related signaling as compared to its HI UVB counterpart. These results indicated that at equivalent exposure, UVB radiation at LI has higher photocarcinogenic potential as compared to its HI counterpart. Since erythema is the observed sunburn at moderate doses and use of sunscreen was not found to associate with reduced sunburn episodes, the biological significance of sunburn with or without sunscreen use warrants further investigation.

Topics: Adult; Animals; Bromodeoxyuridine; Butadienes; Carcinogenesis; Cell Count; Cell Survival; Cells, Cultured; Dermatitis, Contact; DNA Damage; Extracellular Signal-Regulated MAP Kinases; G2 Phase; Humans; Immunosuppression Therapy; Keratinocytes; Mice, Hairless; Mitosis; Mutation; Nitriles; Protein Kinase Inhibitors; Pyrimidine Dimers; Skin Neoplasms; Tumor Suppressor Protein p53; Ultraviolet Rays

Both Aurora-A and -B kinases have been implicated in tumorigenesis; and as such, they represent an attractive therapeutic target. Recent studies found that Aurora-A is a downstream target of mitogen-activated protein kinase 1/ERK2, while Aurora-B has been found to be a prognostic/predictive therapeutic target for epithelial cancer. In a wide range of human cancers, the Ras/Raf/MEK/ERK/MAP kinase pathway is enhanced and the cellular response to growth signals is known to increase. The purpose of this study was to investigate whether the MEK/ERK cascade regulates tumorigenic signaling and radioresistance via the Aurora-B-mediated pathway in a panel of gynecological cancer cell lines. Exponentially growing human endometrial (Ishikawa), cervical (HeLa), cervical (CASKI) and vulva (SiHa) cancer cells were used in culture treated with either control or MEK/ERK inhibitor or AZD1152 before and after irradiation. Western blotting, ERK1/2 siRNA transfection, growth assay in modified monolayer, Annexin V and migration/invasion assays were performed. The specific MEK/ERK inhibitor U0126 decreased the tumorigenic potential and improved the radiation response in all cellular models. The modulation of radioresponse upon U0126 treatment positively correlated with the inhibition of phospho-ERKs and the reduction of Aurora-B kinase expression. In addition, upon U0126 treatment DNA-PKcs protein expression was found to be downregulated, indicating that the improved radiation response may be caused by decreased DNA double-strand damage repair mechanisms. The knockdown of ERK by siRNA confirmed the MEK/ERK-dependent Aurora-B kinase expression. The use of AZD1152, a selective Aurora-B inhibitor, counteracted tumorigenic potential and radioresistance phenotype by highly increasing apoptotic mechanisms in all gynecological cancer cell lines used. Evidence from our experiments show that tumorigenic potential and radiation response in gynecological cancer cells may ensue from a MEK/ERK or Aurora-B inhibition. Together with the close correlation of MEK/ERK and Aurora-B protein expression, this study underlines the potential role of a MEK/ERK/Aurora-B axis whose interruption recovers the antitumor effects of radiotherapy.

Topics: Aurora Kinase B; Butadienes; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; DNA Repair; Female; Genital Neoplasms, Female; HeLa Cells; Humans; MAP Kinase Signaling System; Nitriles; Phosphorylation; Prognosis; Radiation Tolerance; Signal Transduction

Castration-resistant prostate cancer is an incurable heterogeneous disease that is characterized by a complex multistep process involving different cellular and biochemical changes brought on by genetic and epigenetic alterations. These changes lead to the activation or overexpression of key survival pathways that also serve as potential therapeutic targets. Despite promising preclinical results, molecular targeted therapies aimed at such signaling pathways have so far been dismal. In the present study, we used a PTEN-deficient mouse model of prostate cancer to show that plasticity in castration-resistant tumors promotes therapeutic escape. Unlike castration-naïve tumors which depend on androgen receptor and PI3K/AKT signal activation for growth and survival, castration-resistant tumors undergo phenotypic plasticity leading to increased intratumoral heterogeneity. These tumors attain highly heterogeneous phenotypes that are characterized by cancer cells relying on alternate signal transduction pathways for growth and survival, such as mitogen-activated protein kinase and janus kinase/signal transducer and activator of transcription, and losing their dependence on PI3K signaling. These features thus enabled castration-resistant tumors to become insensitive to the therapeutic effects of PI3K/AKT targeted therapy. Overall, our findings provide evidence that androgen deprivation drives phenotypic plasticity in prostate cancer cells and implicate it as a crucial contributor to therapeutic resistance in castration-resistant prostate cancer. Therefore, incorporating intratumoral heterogeneity in a dynamic tumor model as a part of preclinical efficacy determination could improve prediction for response and provide better rationale for the development of more effective therapies.

Topics: Adenocarcinoma; Animals; Antineoplastic Combined Chemotherapy Protocols; Butadienes; Carcinogenesis; Cell Proliferation; Combined Modality Therapy; Disease Models, Animal; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Drug Synergism; Everolimus; Humans; Male; Mice; Mice, Transgenic; Molecular Targeted Therapy; Nitriles; Orchiectomy; Phenotype; Prostate; Prostatic Neoplasms, Castration-Resistant; PTEN Phosphohydrolase; Receptors, Androgen; Sirolimus