IL-6 regulates epithelial ovarian cancer EMT, invasion, and metastasis by modulating Let-7c and miR-200c through the STAT3/HIF-1α pathway.

Interleukin-6 (IL-6) and hypoxia-inducible factor-1α (HIF-1α) play important roles in epithelial-mesenchymal transformation (EMT) and tumor development. Previous studies have demonstrated that IL-6 promotes EMT, invasion, and metastasis in epithelial ovarian cancer (EOC) cells by activating the STAT3/HIF-1α pathway. MicroRNA (miRNA) is non-coding small RNAs that also play an important role in tumor development. Notably, Let-7 and miR-200 families are prominently altered in EOC. However, whether IL-6 regulates the expression of Let-7 and miR-200 families through the STAT3/HIF-1α signaling to induce EMT in EOC remains poorly understood. In this study, we conducted in vitro and in vivo investigations using two EOC cell lines, SKOV3, and OVCAR3 cells. Our findings demonstrate that IL-6 down-regulates the mRNA levels of Let-7c and miR-200c while up-regulating their target genes HMGA2 and ZEB1 through the STAT3/HIF-1α signaling in EOC cells and in vivo. Additionally, to explore the regulatory role of HIF-1α on miRNAs, both exogenous HIF blockers YC-1 and endogenous high expression or inhibition of HIF-1α can be utilized. Both approaches can confirm that the downstream molecule HIF-1α inhibits the expression and function of Let-7c and miR-200c. Further mechanistic research revealed that the overexpression of Let-7c or miR-200c can reverse the malignant evolution of EOC cells induced by IL-6, including EMT, invasion, and metastasis. Consequently, our results suggest that IL-6 regulates the expression of Let-7c and miR-200c through the STAT3/HIF-1α pathway, thereby promoting EMT, invasion, and metastasis in EOC cells.

Pseudolaric Acid B Attenuates High Salt Intake-Induced Hypertensive Left Ventricular Remodeling by Modulating Monocyte/Macrophage Phenotypes.

BACKGROUND Studies in ApoE knockout mice have shown that pseudolaric acid B (PB) can act as an immunomodulatory drug and attenuate atherosclerosis progression by modulating monocyte/macrophage phenotypes. Our previous study demonstrated that high salt intake could shift the phenotype of monocytes/macrophages to an inflammatory phenotype, and that this shift was related to hypertension and hypertensive left ventricular (LV) remodeling. However, no comprehensive assessment of the effects of PB on hypertensive LV remodeling has been conducted. MATERIAL AND METHODS In this study, RAW264.7 macrophages cultured with different concentrations of NaCl were used to investigate the modulating effects of PB on macrophage phenotype. Furthermore, N-nitro-L-arginine methyl ester hypertensive mice were used to investigate the modulating effects of PB on monocyte phenotype. LV remodeling was investigated by echocardiography. LV morphologic staining (for cardiomyocyte hypertrophy and collagen deposition) was performed at the time of sacrifice. RESULTS The results showed that PB significantly improved the viability of RAW264.7 cells, suppressed their phagocytic and migration abilities, and inhibited their phenotypic shift to M1 macrophages. In addition, the blood pressure of PB-treated mice was significantly decreased relative to that of control mice. Furthermore, after PB treatment, the percentage of Ly6Chi monocytes was significantly decreased while that of Ly6Clo monocytes was apparently increased. Moreover, PB preserved LV function and alleviated myocardial fibrosis and cardiomyocyte hypertrophy as measured at the end of the experimental period. The transfer of monocytes from PB-treated mice to hypertensive mice achieved the same effects. CONCLUSIONS Together, these findings indicate that PB exerts its protective effects on hypertensive LV remodeling by modulating monocyte/macrophage phenotypes and warrants further investigation.

The mechanisms of IL-17A on promoting tumor metastasis.

In recent decades, extensive studies have indicated that IL-17A plays an important role in tumor progression and metastasis, but the underlying mechanisms are not immediately clear. In this review, we examined the literature from the recent years concerning the study of IL-17A in four kinds of tumor transfer paths, including hematogenous metastasis, lymphatic metastasis, local invasion and transcoelomic metastasis, to summarize the roles and underlying mechanisms of IL-17A on tumor metastasis.

Autocrine interferon-γ may affect malignant behavior and sensitivity to tamoxifen of MCF-7 via estrogen receptor ß subtype.

Mitogenic actions of estrogens are mediated by two distinct estrogen receptors (ERs), which are critical in the progression and therapeutic response of breast cancer. ER expression is a dynamic phenomenon that is regulated by numerous factors, including cytokines, in the tumor microenvironment. Recently, studies have shown that autocrine production of IL-4 promotes cancer cell growth and there is negative correlation between tumor IL-4 and hormone receptor levels, suggesting that there is crosstalk between cytokine receptors and ER. Thus, we evaluated for interaction between the two ERs and the cytokines IL-4 and IFN-γ, and if this interaction modulates malignant behavior. We identified that ERß exerts protective activity in the progression of breast cancer cell line MCF-7, which co-expresses ERα and ERß. IFN-γ and IL-4 have the opposite effects on malignant biological behavior. Furthermore, we found positive correlation between IFN-γ and ERß expression in MCF-7. We also determined that autocrine IFN-γ in MCF-7 increases mRNA expression of ERß resulting in enhanced sensitivity to tamoxifen (TAM). These results indicate that ERß and autocrine IFN-γ represent two putative targets for breast cancer therapy.

IL6 induces TAM resistance via kinase-specific phosphorylation of ERα in OVCA cells.

About 40-60% of ovarian cancer (OVCA) cases express ERα, but only a small proportion of patients respond clinically to anti-estrogen treatment with estrogen receptor (ER) antagonist tamoxifen (TAM). The mechanism of TAM resistance in the course of OVCA progression remains unclear. However, IL6 plays a critical role in the development and progression of OVCA. Our recent results indicated that IL6 secreted by OVCA cells may promote the resistance of these cells to TAM via ER isoforms and steroid hormone receptor coactivator-1. Here we demonstrate that both exogenous (a relatively short period of treatment with recombinant IL6) and endogenous IL6 (generated as a result of transfection with a plasmid encoding sense IL6) increases expression of pERα-Ser118 and pERα-Ser167 in non-IL6-expressing A2780 cells, while deleting endogenous IL6 expression in IL6-overexpressing CAOV-3 cells (by transfection with a plasmid encoding antisense IL6) reduces expression of pERα-Ser118 and pERα-Ser167, indicating that IL6-induced TAM resistance may also be associated with increased expression of pERα-Ser118 and pERα-Ser167 in OVCA cells. Results of further investigation indicate that IL6 phosphorylates ERα at Ser118 and Ser167 by triggering activation of MEK/ERK and phosphotidylinositol 3 kinase/Akt signaling, respectively, to activate the ER pathway and thereby induce OVCA cells resistance to TAM. These results indicate that IL6 secreted by OVCA cells may also contribute to the refractoriness of these cells to TAM via the crosstalk between ER and IL6-mediated intracellular signal transduction cascades. Overexpression of IL6 not only plays an important role in OVCA progression but also promotes TAM resistance. Our results indicate that TAM-IL6-targeted adjunctive therapy may lead to a more effective intervention than TAM alone.

Autocrine production of interleukin-6 confers ovarian cancer cells resistance to tamoxifen via ER isoforms and SRC-1.

Although 40-60% of ovarian cancer (OVCA)s express estrogen receptor (ER)α, only a minor proportion of patients respond to anti-estrogen treatment with ER antagonist tamoxifen (TAM). The mechanism underlying TAM resistance in the course of OVCA progression is incompletely understood. However, interleukin-6 (IL-6) plays a critical role in the development and progression of OVCA. Here we explore an association between IL-6 and TAM resistance. We demonstrate that both exogenous (a relatively short period of treatment with recombinant IL-6) and endogenous IL-6 (by transfecting with plasmid encoding for sense IL-6) induce TAM resistance in non-IL-6-expressing A2780 cells, while deleting of endogenous IL-6 expression in IL-6-overexpressing CAOV-3 cells (by transfecting with plasmid encoding for antisense IL-6) promotes the sensitivity of these cells to TAM. Further investigation indicates that TAM resistance caused by IL-6 is associated with the alteration of ERα, ERß and steroid hormone receptor coactivator (SRC)-1 expression levels, the protein interactions between SRC-1 and ERα, but not ERß, as well as blockage of estrogen-induced ER receptor nuclear translocation. These results show that IL-6 secreted by OVCA cells may contribute to the refractoriness of these cells to TAM via ER isoforms and SRC-1. Overexpression of IL-6 not only plays an important role in OVCA progression but also contributes to TAM resistance. Our studies suggest that TAM-IL-6-targeted adjunctive therapy may lead to a more effective intervention than TAM alone.

Effects and mechanisms of anti-CD44 monoclonal antibody A3D8 on proliferation and apoptosis of sphere-forming cells with stemness from human ovarian cancer.

OBJECTIVE: CD44(+) human ovarian cancer stem cells (CSCs) and CSC-like cells have been identified and characterized. Compelling evidence has revealed that CD44 is involved in the occurrence and development of cancers. Our previous study showed that sphere-forming cells (SFCs) from the human ovarian cancer cell line SKOV-3 had CSC capacity. Therefore, in the present study, we aimed to investigate the effects and mechanisms of the anti-CD44 monoclonal antibody A3D8 on the proliferation and apoptosis of SFCs to explore novel strategies for the treatment of ovarian cancer. METHODS: We investigated the effects and mechanisms of A3D8 on the proliferation and apoptosis of SFCs using the MTS assay, cell cycle analysis, an annexin V-fluorescein isothiocyanate/propidium iodide kit, Rh123 apoptosis detection kit, real-time reverse transcription polymerase chain reaction and Western blotting. RESULTS: After CD44 ligation by A3D8, SFC cell proliferation was notably attenuated, cell cycle progression was arrested in the S phase, and apoptosis was significantly increased. The effect of A3D8 was enhanced in a dose- and time-dependent manner, and the effect of apoptosis induction by DDP was enhanced by combination treatment with A3D8. Furthermore, the messenger RNA expression levels of p21 and caspase-3 were up-regulated, whereas those of CDK2, cyclinA, and Bcl-2 were down-regulated. The protein expression levels of caspase-3 were up-regulated, whereas those of CDK2, cyclinA, and Bcl-2 were down-regulated. CONCLUSIONS: Our findings indicate that anti-CD44 monoclonal antibodies may be a potential strategy for the treatment of human ovarian cancer after conventional therapy via inhibition of growth and the promotion of apoptosis in SFCs with stemness.

Interleukin-8 secretion by ovarian cancer cells increases anchorage-independent growth, proliferation, angiogenic potential, adhesion and invasion.

It has been shown that IL-8 is elevated in ovarian cyst fluid, ascites, serum, and tumor tissue from ovarian cancer (OVCA) patients, and increased IL-8 expression correlates with poor prognosis and survival. However, the exact role that IL-8 plays in this malignancy or whether IL-8 can regulate malignant behavior has not been established. Here we demonstrate that overexpression of IL-8 in non-IL-8-expressing A2780 cells (by transfecting with plasmid encoding for sense IL-8) increases anchorage-independent growth, proliferation, angiogenic potential, adhesion and invasion while depletion of endogenous IL-8 expression in IL-8-overexpressing SKOV-3 cells (by transfecting with plasmid encoding for antisense IL-8) decreases the above effects. Further investigation indicates that IL-8-stimulated cell proliferation correlates with alteration of cell cycle distribution by increasing levels of cell cycle-regulated Cyclin D1 and Cyclin B1 proteins as well as activation of PI3K/Akt and Raf/MEK/ERK, whereas IL-8-enhanced OVCA cell invasive correlates with increased MMP-2 and MMP-9 activity and expression. Our data suggest that IL-8 secreted by OVCA cells promotes malignant behavior of these cells via inducing intracellular molecular signaling. Therefore, modulation of IL-8 expression or its related signaling pathway may be a promising strategy for controlling the progression and metastasis of OVCA.

Autocrine production of interleukin-8 confers cisplatin and paclitaxel resistance in ovarian cancer cells.

It has been widely reported that interleukin-8 (IL-8) is overexpressed in ovarian cyst fluid, ascites, serum, and tumor tissue from ovarian cancer (OVCA) patients, and elevated IL-8 expression correlates with a poor final outcome and chemosensitivity. However, the role of IL-8 expression in the acquisition of the chemoresistance phenotype and the underlining mechanisms of drug resistance in OVCA cells are not yet fully understood. Here we show that both exogenous (a relatively short period of treatment with recombination IL-8) and endogenous IL-8 (by transfecting with plasmid encoding for sense IL-8) induce cisplatin and paclitaxel resistance in non-IL-8-expressing A2780 cells, while deleting of endogenous IL-8 expression in IL-8-overexpressing SKOV-3 cells (by transfecting with plasmid encoding for antisense IL-8) promotes the sensitivity of these cells to anticancer drugs. IL-8-mediated resistance of OVCA cells exhibits decreased proteolytic activation of caspase-3. Meanwhile, the further study demonstrates that the chemoresistance caused by IL-8 is associated with increased expression of both multidrug resistance-related genes (MDR1) and apoptosis inhibitory proteins (Bcl-2, Bcl-xL, and XIAP), as well as activation of PI3K/Akt and Ras/MEK/ERK signaling. Therefore, modulation of IL-8 expression or its related signaling pathway may be a promising strategy of treatment for drug-resistant OVCA.

[Chemotherapy resistance induced by interleukin-6 in ovarian cancer cells and its signal transduction pathways].

OBJECTIVE: To study the mechanism of chemotherapy resistance caused by interleukin-6 (IL-6) in ovarian cancer cells and its related signal pathways. METHODS: Ovarian cancer cell lines A2780 (IL-6 receptor positive, while non-IL-6-expressing and cisplatin/paclitaxel-responsive) and SKOV3 cell lines (overexpressing of IL-6 receptor and IL-6 and cisplatin/paclitaxel-resistant) were suitable models for this study. The effect of exogenous (a short period of treatment with recombination IL-6) and endogenous IL-6 (by transfecting with plasmid encoding for sense IL-6) in A2780 cells or deleting of endogenous IL-6 expression in SKOV3 cells (by transfecting with plasmid encoding for antisense IL-6) on the sensitivity to cisplatin and paclitaxel was investigated. Meanwhile, the mechanism of chemotherapy resistance caused by IL-6 in ovarian cancer cells and its related signal pathways were also analyzed. RESULTS: We found that both exogenous and endogenous IL-6 induce cisplatin and paclitaxel resistance in non-IL-6-expressing A2780 cells (the resistance multiple to cisplatin and paclitaxel was: exogenous, 6.25 and 7.31; endogenous, 7.13-8.34 and 7.61-10.70), while deleting of endogenous IL-6 expression in IL-6-overexpressing SKOV3 cells promotes its sensitivity to anticancer drugs (the resistance multiple to cisplatin and paclitaxel was 0.15 and 0.10, 0.10 and 0.08). IL-6 significantly up-regulated the expression levels of mRNA and protein of drug resistance-associated genes, MDR1 and GST-π, and apoptosis-inhibiting genes, bcl-2, bcl-xL and XIAP in a dose-dependent manner in A2780 cells. In accordance with this finding, the mRNA and protein levels of MDR1 and GST-π enhanced in sense IL-6-transfected A2780 cells, and reduced in antisense IL-6-transfected SKOV3 cells compared with the corresponding parental and control vector-transfected cells, which had no difference. It was found that PD98059 [mitogen-activated protein kinase-extracellular signal-regulated kinase (MEK) inhibitor] and wortmannin [phosphatidylinositol 3-kinase (PI3K) inhibitor] significantly antagonized IL-6-induced phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B (Akt), respectively, and both of them blocked IL-6-induced cisplatin and paclitaxel resistance and the inhibitory effects of PD98059 and wortmannin were dependent on its concentration. CONCLUSIONS: These data suggest that IL-6-induced chemoresistance may be associated with increase of both drug resistance-associated genes (MDR1 and GST-π) and apoptosis-inhibiting genes (bcl-2, bcl-xL and XIAP), and activation of MEK/ERK and PI3K/Akt. Therefore, modulation of IL-6 expression or its related signaling pathway may be a promising strategy of treatment for drug-resistant ovarian cancer.

Autocrine production of interleukin-6 confers cisplatin and paclitaxel resistance in ovarian cancer cells.

It has been shown that IL-6 is elevated in the serum and ascites of ovarian cancer patients, and increased IL-6 concentration correlates with poor prognosis and chemoresistance. However, the role of IL-6 expression in the acquisition of the chemoresistance phenotype and the underlining mechanisms of drug resistance in ovarian cancer cells remain unclear. Here we demonstrate that both exogenous (a relatively short period of treatment with recombination IL-6) and endogenous IL-6 (by transfecting with plasmid encoding for sense IL-6) induce cisplatin and paclitaxel resistance in non-IL-6-expressing A2780 cells, while deleting of endogenous IL-6 expression in IL-6-overexpressing SKOV3 cells (by transfecting with plasmid encoding for antisense IL-6) promotes the sensitivity of these cells to anticancer drugs. IL-6-mediated resistance of ovarian cancer cells exhibits decreased proteolytic activation of caspase-3. Meanwhile, the further study demonstrates that the chemoresistance caused by IL-6 is associated with increased expression of both multidrug resistance-related genes (MDR1 and GSTpi) and apoptosis inhibitory proteins (Bcl-2, Bcl-xL and XIAP), as well as activation of Ras/MEK/ERK and PI3K/Akt signaling. Therefore, modulation of IL-6 expression or its related signaling pathway may be a promising strategy of treatment for drug-resistant ovarian cancer.

[Relationship of IL-6 and IL-8 secretion in epithelial ovarian cancer cell lines with their sensitivity to tamoxifen as well as MAPK, Akt and estrogen receptor phosphorylation].

AIM: To investigate the relationship of IL-6 and IL-8 secretion in four epithelial ovarian cancer cell lines (A2780, CAOV-3, SKOV-3 and ES-2) with their sensitivity to tamoxifen (TAM) as well as MAPK, Akt and estrogen receptor (ER) phosphorylation, and to explore the mechanism of endocrine therapy resistance caused by IL-6 and IL-8 in ovarian cancer cells. METHODS: Reverse transcription polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA) were performed to analyze the expression of IL-6 and IL-8. MTT assay was carried out to examine the response of ovarian cancer cells to TAM. Western blot was used to detect phosphorylated MAPK, Akt and ER. RESULTS: Except A2780 cells, three other ovarian cancer cells constitutively expressed IL-6 and IL-8. The mRNA levels of IL-6 and IL-8 correlated with their protein levels in four ovarian cancer cells. The four ovarian cancer cells showed different response to TAM. A2780 cells was the most responsive, whereas CAOV-3, SKOV-3 and ES-2 cells were TAM-resistant to a different degree. There was a notable difference in phosphorylated MAPK, Akt and ER (serine 118 and 167) among the four ovarian cancer cells. CONCLUSION: Autocrine production of IL-6 and IL-8 in epithelial ovarian cancer cell lines is inversely associated with cell response to TAM, and positively associated with phosphorylated MAPK, Akt and ER.

[Construction and expression of human IL-8 sense or antisense eukaryotic expression vectors].

AIM: To construct the sense or antisense IL-8 eukaryotic expression vectors. METHODS: Sense or antisense IL-8 full length gene were amplified by RT-PCR and cloned into eukaryotic expression vector pcDNA3.1(+). After the identification by PCR, restriction endonuclease digestion and the nucleotide sequencing, the recombinant vectors were transfected into human ovarian carcinoma A2780 and SKOV3 cell lines transiently by lipofectamine mediation. The expression of IL-8 gene and protein were detected by RT-PCR and ELISA. RESULTS: The sense or antisense IL-8 eukaryotic expression vectors were constructed and verified. The expression of IL-8 gene and protein in A2780 cells transfected with pcDNA3.1(+)-ssIL-8 were increased, whereas the expression of IL-8 protein in SKOV3 cells transfected with pcDNA3.1(+)-asIL-8 was decreased. CONCLUSION: The eukaryotic expression vectors pcDNA3.1(+)-ssIL-8 or pcDNA3.1(+)-asIL-8 have been constructed successfully, which lays a base for further study on roles of IL-8 in ovarian cancer and other tumors.