ag-490 and Carcinoma--Squamous-Cell

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

Angiogenesis is an essential event in tumor growth and metastasis, and immune system also contributes to the tumor evasion. Emerging evidences have suggested the bidirectional link between angiogenesis and immunosuppression. Myeloid-derived suppressor cell (MDSC) is a kind of immunosuppressive cells and plays an important role in this process. However, the actual regulatory mechanisms of angiogenesis and MDSCs in head and neck squamous cell carcinoma (HNSCC) were unclear. In this study, through analyzing the immunohistochemistry staining of human HNSCC tissue microarray, we found that the microvascular density (MVD) was significantly increased in HNSCC patients. We also characterized angiogenic factors p-STAT3, VEGFA, CK2, and MDSCs marker CD11b in HNSCC tissue array, and found the close expression correlation among these markers. To determine the role of JAK2/STAT3 pathway in tumor microenvironment of HNSCC, we utilized AG490 (an inhibitor of JAK2/STAT3) for further research. Results showed that inhibition of JAK2/STAT3 suppressed angiogenesis by decreasing VEGFA and HIF1-α both in vitro and vivo. Moreover, in HNSCC transgenic mouse model, inhibiting JAK2/STAT3 not only suppressed angiogenesis but also reduced MDSCs in the tumor microenvironment through suppressing VEGFA and CK2. Our findings demonstrated the close relationship between angiogenesis and MDSCs in HNSCC, and inhibition of JAK2/STAT3 could reduce tumor-induced angiogenesis and decrease MDSCs.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Carcinoma, Squamous Cell; Cell Line, Tumor; Head and Neck Neoplasms; Human Umbilical Vein Endothelial Cells; Humans; Janus Kinase 2; Mice, Transgenic; Myeloid-Derived Suppressor Cells; Neovascularization, Pathologic; Signal Transduction; STAT3 Transcription Factor; Tumor Microenvironment; Tyrphostins

To investigate the effects of combined inhibition of signal transducer and activator of transcription 3 (STAT3) and hypoxia-inducible factor-1α (HIF-1α) in the enhancement of chemosensitivity of the model of human laryngeal squamous cacinoma in nude mice.. Model nude mice were divided into six groups randomly: control group(A) , cisplatin group(B) , cisplatin and AG490 group(C) , cisplatin and HIF-1α⁻/⁻ group (D), cisplatin combined AG490 and HIF-1α⁻/⁻ group (E), HIF-1α⁻/⁻ group (F) (only in calculating tumor inhibition rate). 3mg/kg cisplatin was administered by peritoneal injection for 3 days. Then cisplatin and 10 mg/kg AG490 were administered every other day for 12 days. The expression of Ki67 and HIF-1α was detected by immunocytochemical method. Western blot was used to detect the expression of p-STAT3.. The expression of HIF-1α in group C and group D were lower than that in group B, and there were significant difference respectively (t₁ = 2.782, t₂ = 3.873, P < 0.05); The expression of HIF-1α in group E was lower than that in group C and group D respectively, and there were significant difference respectively (t₁ = 6.140, t₂ = 3.667, P < 0.01). The expression level of p-STAT3 in group C was markedly lower compared with that in group B, and there were significant difference between them (t = 17.840, P < 0.01); There were no difference between the expression level of p-STAT3 in group D and that in group B (t = 0.038, P > 0.05); The expression level of p-STAT3 in group E was significantly lower compared with that in group C and group D respectively (P < 0.01). Tumor inhibition rate of group E was higher than that in group B, group C , as well as group D respectively and there were significant difference respectively (t₁ = 5.509, P < 0.01; t₂ = 3.422, P < 0.05; t₃ = 2.718, P < 0.05 ). Ki67 index of group E was lower than that in group B, group C as well as group D respectively and there were significant difference respectively(t₁ = 8.307, P < 0.01; t₂ = 3.736, P < 0.05; t₃ = 4.524, P < 0.01).. Combined inhibition of STAT3 and HIF-1α could enhance chemo-sensitivity in the model of human laryngeal squamous cacinoma in nude mice.

Topics: Animals; Antineoplastic Agents; Carcinoma, Squamous Cell; Cisplatin; Drug Resistance, Neoplasm; Hypoxia-Inducible Factor 1, alpha Subunit; Ki-67 Antigen; Laryngeal Neoplasms; Mice; Mice, Nude; Neoplasms, Experimental; STAT3 Transcription Factor; Tyrphostins

Recent research indicates that the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathway may play an important role in chronic inflammation which promotes cancer progression, yet the mechanism is not clear. The present study aimed to investigate the role of the JAK/STAT3 pathway in the growth and cancer-related inflammation (CRI) of esophageal squamous cell carcinoma (ESCC) by studying the crosstalk between the JAK/STAT3 pathway and nuclear factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) which are important inflammatory factors associated with tumorigenesis. Cell growth and the cell cycle were assessed by CCK-8 assays and flow cytometry, respectively. The protein levels of STAT3, phosphorylated STAT3, VEGF, NF-κB p65, phosphorylated NF-κB p65 and COX-2 in ESCC cells following treatment with JAK2 inhibitor for 48 h or interleukin-6 (IL-6) for 24 h were detected. RT-PCR was performed to study the interaction among STAT3, NF-κB and COX-2 by transfection of siRNAs targeted at STAT3 and NF-κB. STAT3 was activated in 3 ESCC cell lines at different levels. Blocking the JAK/STAT3 pathway inhibited cancer growth through regulation of cell growth, cell cycle and angiogenesis. Likewise, abrogation of the JAK/STAT3 pathway decreased CRI by downregulating levels of NF-κB p65 phosphorylation, COX-2 and IL-6 concentration. In addition, CRI and cancer growth were accelerated by IL-6 through stimulation of the JAK/STAT3 and NF-κB p65 pathway. Moreover, STAT3 and NF-κB both regulated COX-2 as a downstream gene. The JAK/STAT3 pathway is an important pathway which links CRI and cancer growth through IL-6 and crosstalk with the NF-κB p65 subunit and COX-2. The STAT3 pathway could be a novel target both for cancer treatment and prevention in ESCC.

Topics: Carcinoma, Squamous Cell; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 2; Enzyme Inhibitors; Esophageal Neoplasms; Esophageal Squamous Cell Carcinoma; Humans; Inflammation; Interleukin-6; Janus Kinase 2; NF-kappa B; Phosphorylation; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

To detect the expression of phosphorylated-signal transducer and activator of transcription 3 (p-Stat3) and myeloid leukemia-1 (Mcl-1) as well as their correlation, and to investigate the functional role of Stat3 and Mcl-1 in the pathogenesis of esophageal squamous cell carcinoma (ESCC).. Stat3 activity in ESCC cells was inhibited with JAK/Stat3 inhibitors (AG490 or JSI-124). Specific siRNA was used to inhibit the Stat3 expression. Cell apoptosis was detected by flow cytometry. Expression of Mcl-1 protein was determined by Western blotting. Expression of phospho-Stat3 (Tyr705) and myeloid leukemia-1 (Mcl-1) proteins in ESCC tissues was detected by tissue microarray and immunohistochemistry. The relationship between p-Stat3 or Mcl-1 aberrant expression and clinicopatholohical features of ESCC was analyzed. The correlation of their expression was also analyzed.. Suppression of the Stat3 signaling activation in ESCC cells led to marked apoptosis, and dramatic reduction of Mcl-1 protein. The positive rate of phospho-Stat3 (Tyr705) expression was 45.0% in 50/111 of the ESCC tissue samples. The lower the degree of tumor differentiation, the higher the positive rate of phospho-Stat3 (Tyr705), showing a significant difference (P = 0.018). The positive rate of Mcl-1 protein expression was 72.1% (80/111), and the lower the degree of tumor differentiation was, the higher there was the positive rate of Mcl-1, with a significant difference (P = 0.026). There was a positive correlation between the expressions of p-Stat3 and Mcl-1 proteins (P = 0.012).. In a subset of ESCC tissues, p-Stat3 (Tyr705) and Mcl-1 are overexpressed and positively correlated with each other, and both are correlated with tumor differentiation. Persistent activation of Stat3 contributes to apoptotic resistance in ESCC cells, and may be at least partly mediated through upregulation of Mcl-1.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Squamous Cell; Cell Differentiation; Cell Line, Tumor; Cell Survival; Esophageal Neoplasms; Esophageal Squamous Cell Carcinoma; Humans; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Grading; Neoplasm Staging; Phosphorylation; RNA, Small Interfering; STAT3 Transcription Factor; Tyrphostins

Serum amyloid A (SAA) is an acute-phase reactant, the blood level of which is often elevated in response to some types of neoplasia. Here, we investigated expression of the gene SAA1 and the protein SAA in head and neck squamous cell carcinoma (HNSCC) and normal oral mucosal tissues as well as blood SAA levels in HNSCC patients. Also, we investigated the effects of inhibiting signal transducer and activator of transcription 3 (STAT3) signaling on SAA1 expression in the HNSCC cell line SAS. Serum SAA levels in HNSCC patients were significantly higher than those in healthy volunteers. In addition, real-time quantitative reverse transcription-polymerase chain reaction analysis revealed a significantly higher SAA1 expression level in HNSCC than in normal mucosa (P < 0.0001). Furthermore, Western blot and immunohistochemical analyzes revealed that high expression of SAA in carcinomas was detected predominantly in tumor cells, but not in normal mucosal tissues. An inhibitor of STAT3 activation, AG490, significantly reduced SAA1 expression in SAS cells. These data demonstrated that SAA was up-regulated in HNSCC through the Janus kinase-STAT3 pathway.

Topics: Aged; Blotting, Western; Carcinoma, Squamous Cell; Cell Line, Tumor; Enzyme Inhibitors; Female; Gene Expression Regulation, Neoplastic; Gingiva; Head and Neck Neoplasms; Humans; Immunohistochemistry; Janus Kinases; Male; Mouth Mucosa; Neoplasm Staging; Reverse Transcriptase Polymerase Chain Reaction; Serum Amyloid A Protein; STAT3 Transcription Factor; Tyrphostins; Up-Regulation

The family of signal transducers and activators of transcription (STAT) are transcription factors. Among them, STAT1 is associated with an apoptosis pathway, while STAT3 is associated with tumorigenicity in various cancer cells. In order to investigate the primary roles of STAT1 and STAT3 in head and neck squamous cell carcinoma (HNSCC), we blocked STAT3 with two JAK inhibitors: AG490 (JAK2-STAT3 pathway inhibitor) and JAK total inhibitor. When we inhibited STAT3 with AG490, significant cell death was observed. However, in the case of JAK kinase total inhibitor, no cell growth retardation was observed. We focused on the role of STAT1 in this phenomenon. Suppression of STAT1 by si-RNA resulted in increased cell survival. Furthermore, the growth inhibitory effect of AG490 was reduced by treatment with si-RNA of STAT1. These results reveal that STAT1 is required to promote the tumor killing effect of STAT3 inhibition in HNSCC.

Topics: Antineoplastic Agents; Blotting, Western; Carcinoma, Squamous Cell; Cell Death; Cell Line, Tumor; Head and Neck Neoplasms; Humans; RNA, Small Interfering; STAT1 Transcription Factor; STAT3 Transcription Factor; Tyrphostins

Numerous reports suggest that interleukin-6 (IL-6) promotes survival and proliferation of tumor cells through the phosphorylation of a cell-signaling protein, signal-transducer-and-activator-of-transcription-3 (STAT3). Constitutive activation of STAT3 in head and neck squamous cell carcinoma (HNSCC) and its role in proliferation of this tumor has been demonstrated. Thus, agents that can suppress STAT3 activation have potential for the treatment of HNSCC. In the present report, we demonstrate that most HNSCC cell lines had constitutively active STAT3 and that curcumin (diferuloylmethane), a pharmacologically safe agent in humans, inhibited STAT3 phosphorylation in a dose- and time-dependent manner. Nuclear translocation of STAT3 was also inhibited by curcumin. The inhibition of STAT3 activation by curcumin was reversible, although even 24 hr after curcumin removal, only partial reversal occurred. Besides inhibiting constitutive expression, curcumin also abrogated the IL-6-induced activation of STAT3 in HNSCC cells. When compared with AG490, a well-characterized JAK2 inhibitor, curcumin was more rapid (30 min vs. 4 hr) and more potent (25 microM vs. 100 microM) inhibitor of STAT3 phosphorylation. Curcumin was also a more potent inhibitor of HNSCC cell proliferation than AG490. Overall, our results demonstrated that curcumin is a potent inhibitor of constitutive and IL-6-induced STAT3 phosphorylation. This mechanism may be at least partially responsible for curcumin's ability to suppress proliferation of HNSCC cells.

Topics: Antineoplastic Agents; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Curcumin; Head and Neck Neoplasms; Humans; Interleukin-6; Janus Kinase 2; Lymphatic Metastasis; Phosphorylation; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Signal Transduction; STAT3 Transcription Factor; Tongue Neoplasms; Tyrphostins

Originally characterized as a growth factor for erythrocytes, erythropoietin (EPO) is used to treat anemia and fatigue in cancer patients receiving radiation therapy and chemotherapy. EPO and the EPO receptor (EPOR) are expressed in nonhematopoietic cells and cancers. However, the role of EPO and EPOR within nonhematopoietic cancer cells remains incompletely understood. Although a recent clinical trial demonstrated worse tumor control and survival in head and neck cancer patients treated with EPO, the role of EPO and EPOR in head and neck squamous cell carcinoma (HNSCC) has not been examined. In the present study, we demonstrate the previously unrecognized EPO-mediated invasion by HNSCC cells through the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway. Furthermore, we confirmed the expression of EPO and EPOR in a panel of human HNSCC cell lines and tissue specimens. Pharmacological doses of EPO also had a limited proliferation effect in these cell lines. These results define a novel role for EPO in mediating tumor cell invasion. Increased levels of EPO and EPOR in lymph node metastases as compared to primary tumors from HNSCC patients further support the role of EPO/EPOR in HNSCC disease progression and metastasis.

Topics: Aged; Aged, 80 and over; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; DNA-Binding Proteins; Enzyme Activation; Erythropoietin; Female; Head and Neck Neoplasms; Humans; Janus Kinase 2; Male; Middle Aged; Milk Proteins; Mutation; Neoplasm Invasiveness; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Receptors, Erythropoietin; Signal Transduction; STAT5 Transcription Factor; Trans-Activators; Tyrphostins