ag-490 and Neoplasm-Metastasis

The precise role of pre-mRNA processing factors (PRPs) in human tumorigenesis has not been yet explored. The object of the present study was to explore the effects of PRP3 in a common metastatic skin cancer, keratinocyte-derived cutaneous squamous cell carcinoma (cSCCs). RT-qPCR and western blotting were conducted to measure the expression levels of PRP3 in various cSCC cell lines and cSCC tissues. A benign epidermal keratinocyte cell line was transfected with a eukaryotic expression plasmid to overexpress PRP3. In addition, the endogenous expression level of PRP3 in cSCC cells was silenced using a short hairpin RNA method, and the role of PRP3 on cell proliferation and migration was examined by Cell Counting Kit-8, colony formation, wound healing assay and Transwell assays following knockdown in cSCC cells, and overexpression in keratinovcyte cells. Elevated levels of PRP3 mRNA and protein were noted in cSCC cell lines or cSCC tissues compared with actinic keratosis (AK) or benign epidermal keratinocyte cell line, respectively. Upregulation of PRP3 expression was found to be associated with poor clinical outcomes in patients with cSCCs. The upregulation of PRP3 promoted cell viability, metastasis and the activity of the JAK2/STAT3 pathway in epidermal keratinocyte cells. Interestingly, loss of PRP3 had no obvious impact on cell viability and migration in benign epidermal keratinocyte cells. Functionally, the inhibition of the JAK2/STAT3 pathway reversed the increased cell viability and migration of cSCC cells induced by PRP3. Taken together, the present observations indicated that PRP3 served as a tumor active factor in cSCCs by targeting the JAK2/STAT3 pathway. Moreover, it is implied that impeding the PRP3 activity may selectively constrain cancer cell growth and migration with limited effect on normal skin cells.

Topics: Carcinoma, Squamous Cell; Cell Line; Cell Movement; Cell Proliferation; Humans; Janus Kinase 2; Keratinocytes; Keratosis, Actinic; Middle Aged; Neoplasm Metastasis; Nuclear Proteins; Prognosis; Ribonucleoprotein, U4-U6 Small Nuclear; RNA Interference; RNA, Small Interfering; Signal Transduction; Skin Neoplasms; STAT3 Transcription Factor; Survival Rate; Tyrphostins; Up-Regulation

Transforming growth factor β1 (TGFβ1) is a cytokine with multiple functions. TGFβ1 significantly induces migration and invasion of liver cancer cells. However, the molecular mechanisms underlying this effect remain unclear. Epithelial‑to‑mesenchymal transition (EMT) is crucial for the development of invasion and metastasis in human cancers. The aim of the present study was to determine whether TGFβ1‑induced EMT promoted migration and invasion in HepG2 cells. The underlying mechanism and the effect of EMT on HepG2 cells were also investigated. The results demonstrated that TGFβ1 may induce EMT to promote migration and invasion of HepG2 cells, and this effect depends on activation of the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway. JAK/STAT3 signaling is involved in human malignancies, including lung cancer, and is implicated in cell transformation, tumorigenicity, EMT and metastasis. In the present study, TGFβ1 also activated JAK/STAT3 signaling in HepG2 cells and promoted Twist expression, but these events were abolished by treatment with the STAT3 inhibitor AG490. Additionally, Twist siRNA blocked TGFβ1‑induced EMT. Thus, TGFβ1 was shown to induce EMT, thereby promoting the migration and invasion of HepG2 cells via JAK/STAT3/Twist signaling.

Topics: Cell Movement; Cell Proliferation; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Hep G2 Cells; Humans; Janus Kinases; Liver Neoplasms; Neoplasm Invasiveness; Neoplasm Metastasis; RNA, Small Interfering; Signal Transduction; STAT3 Transcription Factor; Transforming Growth Factor beta1; Twist-Related Protein 1; Tyrphostins

Combination treatment with cetuximab and CPT-11 produces beneficial and synergistic effects in wild-type RAS metastatic colorectal cancer (mCRC) patients. However, the mechanism underlying this synergism is not yet understood. We examined whether cetuximab had a synergistic effect with CPT-11 and its active metabolite, SN38, and examined the molecular mechanism of the synergism between cetuximab and SN38 in CRC cells with various mutational status. We hypothesized that cetuximab promotes sensitivity to SN38 via suppression of heat shock protein 27 (HSP27), a protein involved in multidrug resistance through blocking the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway, which is associated with chemosensitivity. Four human CRC cell lines with different RAS and BRAF mutational status were used. Expression levels of HSP27 protein correlated with SN38 sensitivity in these cell lines (R=0.841, p=0.159). Exposure to cetuximab and various concentration of AG490, an inhibitor of JAK2, STAT3 and HSP27 protein levels, except in the KRAS G12V mutant line, SW620. A synergistic effect of cetuximab in combination with SN38 was observed in RAS and BRAF wild-type cells (here, Caco2), but not in the three other RAS- or BRAF-mutated cell lines. These results indicate that cetuximab may promote sensitivity to SN38 via suppression of HSP27 through blocking the JAK/STAT pathway in Caco2 cells. The mutational status of numerous downstream effectors, such as RAS and BRAF, is important in mono- or combination therapy with cetuximab. In conclusion, cetuximab may promote SN38 sensitivity via suppression of HSP27, through blocking the JAK/STAT signaling pathway, and shows synergistic effects when combined with SN38 in wild-type RAS CRC cells.

Topics: Antineoplastic Combined Chemotherapy Protocols; Camptothecin; Cell Line, Tumor; Cell Proliferation; Cetuximab; Colorectal Neoplasms; Drug Resistance, Neoplasm; Drug Synergism; Gene Expression Regulation, Neoplastic; HSP27 Heat-Shock Proteins; Humans; Irinotecan; Janus Kinase 2; Mutation; Neoplasm Metastasis; Proto-Oncogene Proteins B-raf; Proto-Oncogene Proteins p21(ras); Signal Transduction; STAT3 Transcription Factor; Tyrphostins

To investigate the effect of Janus kinase (JAK) inhibitor AG490 on invasion and metastasis of the human breast cancer cell MDA-MB-231, and to explore the regulating role of JAK-STAT3 signaling pathway when the breast cancer occurs to the invasiveness and metastasis.. The human breast cancer cell MDA-MB-231 was used as the research object, and AG490 was as Janus kinase inhibitor. The adhesion of MDA-MB-231 cell attaching to matrigel was measured with MTT assay. The invasion and metastasis potential were evaluated with transwell chamber. The P-STAT3 protein in cell was detected by Western-blot.. Janus kinase inhibitor AG490 could make that the expression of P-STAT3 in human breast cancer cell MDA-MB-231 became weak, and that the abilities of adhesion, invasion and metastasis were also dropping down as compared with the control group (P < 0.01).. JAK-STAT3 signaling pathway participates in regulating the invasion and metastasis of human breast cancer. Inhibiting the activation of JAK-STAT3 signaling pathway can suppress the invasion and metastasis of human breast cancer.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Adhesion; Cell Line, Tumor; Humans; Janus Kinases; Neoplasm Metastasis; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

The molecular mechanisms that promote progression of localized prostate cancer to hormone-refractory and disseminated disease are poorly understood. Prolactin (Prl) is a local growth factor produced in high-grade prostate cancer, and exogenously added Prl in tissue or explant cultures of normal and malignant prostate is a strong mitogen and survival factor for prostate epithelium. The key signaling proteins that mediate the biological effects of Prl in prostate cancer are Signal Transducer and Activator of Transcription (Stat)-5a/5b via activation of Janus kinase-2. Importantly, inhibition of Stat5a/b in prostate cancer cells induces apoptotic death. Using a specific Prl receptor antagonist (Delta1-9G129R-hPRL), we demonstrate here for the first time that autocrine Prl in androgen-independent human prostate cancer cells promotes cell viability via Stat5 signaling pathway. Furthermore, we examined a unique clinical material of human hormone refractory prostate cancers and metastases and show that autocrine Prl is expressed in 54% of hormone-refractory clinical human prostate cancers and 62% prostate cancer metastases. Finally, we demonstrate that autocrine Prl is expressed from both the proximal and distal promoters of the Prl gene in clinical human prostate cancers and in vivo and in vitro human prostate cancer models, independently of pituitary transcription factor-1 (Pit-1). Collectively, the data provide novel evidence for the concept that autocrine Prl signaling pathway is involved in growth of hormone-refractory and metastatic prostate cancer. The study also provides support for the use of Prl receptor antagonists or other therapeutic strategies to block the Prl-Janus kinase-2-Stat5 signaling pathway in advanced prostate cancer.

Topics: Animals; Cell Line, Tumor; Cell Survival; Gene Expression Regulation, Neoplastic; Humans; Immunoblotting; Janus Kinase 2; Male; Mice; Mice, Nude; Neoplasm Metastasis; Neoplasms, Experimental; Oligodeoxyribonucleotides, Antisense; Phosphorylation; Prolactin; Promoter Regions, Genetic; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; STAT5 Transcription Factor; Transcription, Genetic; Transplantation, Heterologous; Tumor Suppressor Proteins; Tyrphostins

Metastatic breast cancer is an incurable disease, often characterized by poor response to standard chemotherapy, which is mainly based on anthracyclines and taxanes. Thus, increasing tumor cell sensitivity to these agents is an attractive goal towards improving the clinical management of this disease. The present study investigates the effects of signal transducer and activator of transcription 3 (Stat3) inhibition on the response of the highly metastatic MDA-MB-231 human breast adenocarcinoma cell line to doxorubicin (DOX). Stat3 is a transcription factor often constitutively activated in breast tumors and cancer cell lines, and is thought to contribute to malignant transformation and progression by transactivation of a host of target genes involved in cell proliferation and survival, angiogenesis and invasiveness. Our results indicate that (a) untreated MDA-MB-231 cells express higher baseline levels of (activated) pTyr(705)Stat3, that are further upregulated following exposure to DOX, than the non-metastatic MCF-7 cell line; (b) inhibiting the Stat3 signaling pathway, by exposure to the tyrphostin AG490 (an inhibitor of the upstream activating Janus kinases), by transfection with a dominant-negative form of Stat3 or by treatment with satraplatin (a tetravalent platinum derivative that inhibits Stat3 activation), increases breast cancer cell response to the proapoptotic effect of DOX (to different extents). In addition, the latter two approaches have been shown to interfere with expression of one or more antiapoptotic proteins. Overall, these observations suggest that suppression of Stat3 signaling may provide a potential therapeutic approach to overcoming DOX resistance in metastatic breast cancer cells.

Topics: Antineoplastic Agents; Apoptosis; Breast Neoplasms; Cell Line, Tumor; Cell Survival; Doxorubicin; Female; Flow Cytometry; Humans; Immunoblotting; Neoplasm Metastasis; Organoplatinum Compounds; Protein-Tyrosine Kinases; Signal Transduction; STAT3 Transcription Factor; Transfection; Tyrphostins

To investigate the effect and mechanism of blockade of STAT3 signaling pathway by JAK specific inhibitor-AG490 on invasion and metastasis of human highly metastatic pancreatic cancer line SW1990 in vitro.. AG490 was added into the culture media for SW1990 cells. The invasion ability of SW1990 cells was determined by cell invasion assay kit. Western blot was performed to detect the protein expression of the STAT3, phosphorylated STAT3 (p-STAT3), MMP-2 and VEGF. RT-PCR was performed to detect the mRNA expression of the MMP-2 and VEGF.. 20 micromol/L AG490 significantly inhibited the invasion ability of SW1990 cells and the inhibitory rate of invasion ability was (77.67 +/- 7.79) %. The use of AG490 not only markedly reduced the protein expression of p-STAT3, MMP-2 and VEGF, but also greatly reduced the mRNA expression of MMP-2 and VEGF.. Blocking STAT3 activation with AG490 can inhibit the invasion and metastasis ability of pancreatic cancer cells in vitro through down-regulation of MMP-2 and VEGF expression. Blocking STAT3 signaling pathway may provide a novel strategy in prevention of invasion and metastasis of pancreatic cancer.

Topics: Antineoplastic Agents; Blotting, Western; Cell Line, Tumor; Dose-Response Relationship, Drug; Gene Expression Regulation, Neoplastic; Humans; Janus Kinases; Matrix Metalloproteinase 2; Neoplasm Invasiveness; Neoplasm Metastasis; Pancreatic Neoplasms; Phosphorylation; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; STAT3 Transcription Factor; Tyrphostins; Vascular Endothelial Growth Factor A

Disruption of apoptosis may allow metastatic cell survival and confer resistance to chemotherapeutic drugs. We have analysed the molecular pathways that activate these survival genes in specific sites of metastasis. Estrogen receptor-negative breast cancer cell line MDA-MB435 and two metastatic sublines derived from lung (435L) and brain (435B) were analysed for the expression of members of the Bcl-2 family of apoptosis regulators. The levels of Bcl-2 were higher in the metastatic sublines than in parental cells, which correlated with the activation of Stat3, but not with the expression and/or activation of known bcl-2 transcription factors (CREB and WT1). In the brain subline, both expression of Bcl-2 and Stat3 activation were induced by epidermal growth factor and abrogated after treatment with kinase inhibitors specific for epidermal growth factor receptor or Jak2. Furthermore, transfection of 435B with a dominant-negative Stat3 markedly reduced the expression of Bcl-2 protein, whereas transient expression of a constitutively active Stat3 increased Bcl-2 in parental 435 cells. In addition, blockade of Stat3 activation by treatment with epidermal growth factor receptor and Jak2 kinase inhibitors or transfection with a dominant negative Stat3, sensitizes 435B cells to chemotherapy-induced apoptosis. Our data suggest that an increased activation of the Stat3-Bcl-2 pathway in estrogen receptor-negative metastatic breast cancer cell lines confer a survival advantage to these cells and contribute to their chemoresistance.

Topics: Antineoplastic Agents; Apoptosis; bcl-X Protein; Brain Neoplasms; Breast Neoplasms; Carcinoma; Cyclic AMP Response Element-Binding Protein; DNA-Binding Proteins; Enzyme Inhibitors; ErbB Receptors; Female; Humans; Janus Kinase 2; Lung Neoplasms; Neoplasm Metastasis; Neoplasms, Hormone-Dependent; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Receptors, Estrogen; STAT3 Transcription Factor; Trans-Activators; Transcription, Genetic; Tumor Cells, Cultured; Tyrphostins