Red flags alerting a posterior cranial fossa tumor from audiovestibular perspectives - a review.

BACKGROUND: There is no comprehensive and up-to-date overview of audiovestibular approach to the posterior fossa tumors in the literature. OBJECTIVE: This paper reviewed the literature relating to tumors at the posterior cranial fossa to find red flags alerting a posterior fossa lesion from audiovestibular perspectives. METHODS: This review was developed from articles published in those journals listed on the journal citation reports. Through the PubMed database, Embase, Google Scholar, and Cochrane library, 60 articles were finally obtained based on the PRISMA guidelines for reporting reviews. RESULTS: The presence of one red flag indicates a positive predictive value of 33% for detecting a posterior fossa lesion. Clinical features, namely, 1) mid-frequency sudden sensorineural hearing loss (SNHL), 2) bilateral sudden SNHL, and 3) rebound nystagmus may indicate a posterior fossa lesion, representing one, two, and three red flags, respectively. CONCLUSION: Those with 1) mid-frequency sudden SNHL, 2) bilateral sudden SNHL, and 3) rebound nystagmus trigger one, two, and three red flags, respectively, alerting clinicians the possibility of a posterior fossa lesion, which warrant MR imaging to exclude life-threatening or treatable conditions. SIGNIFICANCE: Patients with posterior fossa tumors may have potential life-threatening outcome.

Incomplete Recovery from the Radiocontrast-Induced Dysregulated Cell Cycle, Adhesion, and Fibrogenesis in Renal Tubular Cells after Radiocontrast (Iohexol) Removal.

Contrast-induced nephropathy (CIN) is one of the most common causes of acute kidney injury (AKI). However, management is still limited, and the cellular response to radiocontrast removal for CIN remains unclear. This study aimed to explore the latent effects of iohexol in cultured renal tubular cells with or without the removal of iohexol by medium replacement. HK2 renal tubular cells were subcultured 24 h before use in CIN experiments. Three treatment groups were established: the control, a radiocontrast (iohexol)-only group at 75 mg I/mL (I-75), and iohexol exposure for 24 h with culture medium replacement (I-75/M). Cell cycle arrest, fibrogenic mediator assays, cell viability, cell function, and cell-cycle-related protein expression were compared between groups. Iohexol induced numerous changes in HK2 renal tubular cells, such as enlarged cell shape, cell cycle arrest, increased apoptosis, and polyploidy. Iohexol inhibited the expression of cyclins, CDKs, ZO-1, and E-cadherin but conversely enhanced the expression of p21 and fibrosis-related genes, including TGF-ß1, CTGF, collagen I, collagen III, and HIF-1α within 60 hr after the exposure. Except for the recovery from cell cycle arrest and cell cycle gene expression, notably, the removal of iohexol by medium replacement could not fully recover the renal tubular cells from the formation of polyploid cells, the adhesion or spreading, or the expression of fibrosis-related genes. The present study demonstrates, for the first time, that iohexol exerts latent cytotoxic effects on cultured renal tubular cells after its removal, suggesting that these irreversible cell changes may cause the insufficiency of radiocontrast reduction in CIN, which is worth investigating further.

The association between mortality and use of Chinese herbal medicine among incident stage IV esophageal cancer patients: A retrospective cohort study with core herbs exploration.

Esophageal cancer (EC) remains a leading cause of death worldwide and in Taiwan. The prognosis of advanced-stage EC is notably poor, and the treatment options are limited. Chinese herbal medicine (CHM) has been widely used as a complementary treatment for cancer, yet the long-term effect of CHM in stage IV EC remains unclear. The multi-institutional cohort obtained from the Chang Gung research database (CGRD) was used to study the long-term outcome of CHM use among incident stage IV EC patients from 1 January 2002, to 31 December 2018. All patients were followed up to 5 years or the occurrence of death. The overall survival (OS) and disease-specific survival rates were conducted using Kaplan-Meier estimation. Overlap weighing and landmark analysis were used to eliminate confounding and immortal time biases. Furthermore, we demonstrated the core CHMs for stage IV EC by using the Chinese herbal medicine network (CMN) analysis on prescriptions. Nine hundred eighty-five stage IV EC patients were analyzed, including 74 CHM users and 911 non-CHM users. We found the use of CHM was associated with a higher 5-year overall survival rate than CHM nonusers (the cumulative probability: 19.52% versus 6.04%, log-rank test: p < 0.001, and the p < 0.001 with overlap weighting). In addition, the overall median survival time was about 7 months longer among CHM users. Moreover, the lower 1-, 3-, 5-year disease-specific survival rates were higher among CHM users. Additionally, the risk of all-cause mortality was lower among CHM users when considering accessible demographic covariates (adjusted hazard ratio: 0.59, 95%CI: 0.39, 0.89, p = 0.011). Furthermore, the CMN analysis revealed that CHMs improved health while relieving tumor burden. For example, Hedyotis diffusa Willd . was the core CHM with an anti-cancer effect, while Fritillaria thunbergii Miq and Sevilla maindronide Rochebrune were used together to relieve cancer-related gastrointestinal discomfort. The use of CHM seems safe and possibly beneficial among stage IV EC patients with a higher 5-year OS. Further clinical trials on CHM were guaranteed to explore the role of CHM in managing stage IV EC patients.

Chidamide plus Tyrosine Kinase Inhibitor Remodel the Tumor Immune Microenvironment and Reduce Tumor Progression When Combined with Immune Checkpoint Inhibitor in Naïve and Anti-PD-1 Resistant CT26-Bearing Mice.

Combined inhibition of vascular endothelial growth factor receptor (VEGFR) and the programmed cell death protein 1 (PD-1) pathways has shown efficacy in multiple cancers; however, the clinical outcomes show limited benefits and the unmet clinical needs still remain and require improvement in efficacy. Using murine colon carcinoma (CT26) allograft models, we examined the efficacy and elucidated novel tumor microenvironment (TME) remodeling mechanisms underlying the combination of chidamide (a benzamide-based class l histone deacetylase inhibitor; brand name in Taiwan, Kepida®) with VEGF receptor tyrosine kinase inhibitor (TKIs; cabozantinib/regorafenib, etc.) and immune checkpoint inhibitors (ICIs; anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies). The TME was assessed using flow cytometry and RNA-sequencing to determine the novel mechanisms and their correlation with therapeutic effects in mice with significant treatment response. Compared with ICI alone or cabozantinib/regorafenib + ICI, combination of chidamide + cabozantinib/regorafenib + ICI increased the tumor response and survival benefits. In particular, treatment of CT26-bearing mice with chidamide + regorafenib + anti-PD-1 antibody showed a better objective response rate (ORR) and overall survival (OS). Similar results were observed in anti-PD-1 treatment-resistant mice. After treatment with this optimal combination, in the TME, RNA-sequencing revealed that downregulated mRNAs were correlated with leukocyte migration, cell chemotaxis, and macrophage gene sets, and flow cytometry analysis showed that the cell numbers of myeloid-derived polymorphonuclear suppressor cells and tumor-associated macrophages were decreased. Accordingly, chidamide + regorafenib + anti-PD-1 antibody combination therapy could trigger a novel TME remodeling mechanism by attenuating immunosuppressive cells, and restoring T-cell activation to enhance ORR and OS. Our studies also showed that the addition of Chidamide to the regorafenib + anti-PD-1 Ab combination could induce a durable tumor-specific response by attenuating immune suppression in the TME. In addition, this result suggests that TME remodeling, mediated by epigenetic immunomodulator combined with TKI and ICI, would be more advantageous for achieving a high objective response rate, when compared to TKI plus ICI or ICI alone, and maintaining long-lasting antitumor activity.

Carboplatin-Induced Thrombocytopenia through JAK2 Downregulation, S-Phase Cell Cycle Arrest and Apoptosis in Megakaryocytes.

Chemotherapy-induced thrombocytopenia (CIT) is a common complication when treating malignancies with cytotoxic agents wherein carboplatin is one of the most typical agents causing CIT. Janus kinase 2 (JAK2) is one of the critical enzymes to megakaryocyte proliferation and differentiation. However, the role of the JAK2 in CIT remains unclear. In this study, we used both carboplatin-induced CIT mice and MEG-01 cell line to examine the expression of JAK2 and signal transducer and activator of transcription 3 (STAT3) pathway. Under CIT, the expression of JAK2 was significantly reduced in vivo and in vitro. More surprisingly, the JAK2/STAT3 pathway remained inactivated even when thrombopoietin (TPO) was administered. On the other hand, carboplatin could cause prominent S phase cell cycle arrest and markedly increased apoptosis in MEG-01 cells. These results showed that the thrombopoiesis might be interfered through the downregulation of JAK2/STAT3 pathway by carboplatin in CIT, and the fact that exogenous TPO supplement cannot reactivate this pathway.

CC-01 (chidamide plus celecoxib) modifies the tumor immune microenvironment and reduces tumor progression combined with immune checkpoint inhibitor.

Immune checkpoint inhibitors (ICIs) have shown clinical benefit in solid tumors, with modest rates of clinical response. Hence, improved therapeutic approaches need to be investigated. Herein, we assessed a combination of chidamide plus celecoxib (called CC-01) combined with programmed cell death protein 1 (PD-1) blockade in a CT26 model as potent tumor microenvironment (TME) regulator. The antitumor activity was assessed by measuring tumor size, overall response rate, and survival rate. Immune profiling of tumor-infiltrating lymphocytes was performed by flow cytometry. Tumor tissues were assessed by chip assay to predict the possible pathway. Tumor size was significantly reduced in mice treated with CC-01 combined with or without anti-PD-1 antibody, however the triple combination therapy consistently demonstrated that it significantly increased both the ORR and survival rate in term of clinical applications. In the combination group, immune landscape profiling revealed decreased populations of immunosuppressive regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. Analysis of the mouse tumor chip data using Gene Ontology enrichment analysis of biological processes revealed that the triple combination upregulated genes associated with responses to interferon-gamma. Our results demonstrated that CC-01 possessed potent TME regulatory properties, augmenting the antitumor effect when combined with ICIs. This antitumor effect was achieved by altering the immune landscape in TILs (tumor-infiltrating lymphocytes) and was associated with immune cell activation in the TME. Furthermore, CC-01 demonstrated potent anticancer immune response activity, mainly reducing the number and function of several immunosuppressive cells. The combination of CC-01 with an ICI will further enhance the anticancer effect and boost the immune response rate. Collectively, our results support the clinical evaluation of CC-01 in combination with ICIs in several advanced cancers.

Anticoagulant effect of wogonin against tissue factor expression.

Tissue factor (TF) is the primary cause of atherothrombosis, the rupture of atherosclerotic plaques with subsequent thrombosis, leading to acute cardiovascular events, such as myocardial infarction and stroke. Wogonin (Wog) is an active component of Scutellaria baicalensis, used for inflammatory diseases, atherosclerosis, and hyperlipidemia. The anticoagulant effect of Wog on TF expression remains unexplored. In this study, we have investigated the effects of Wog on TF gene expression and its underlying molecular mechanism in human vascular endothelial cells (ECs). We found that Wog dose-dependently inhibited PMA-enhanced TF mRNA, protein, and activity in ECs. This inhibition was attributed to its decreasing nuclear accumulations of transcription factors, phospho-c-Jun and early growth response-1(Egr-1), not nuclear factor-κB (NF-κB), through blocking extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways. Reduction by Wog of Egr-1 nuclear level and Egr-1/DNA binding activity was associated with its inhibition of Egr-1 de novo synthesis. Wog as well as inhibitors to ERK and JNK suppressed TF promoter activity and protein expression in reporter gene and Western blot analyses. Furthermore, it also exhibited anticoagulant function by inhibiting TF expression and activity in tumor necrosis factor-alpha (TNF-α)- and lipopolysaccharide (LPS)-treated ECs and THP-1 cells. These results suggest that Wog inhibits ERK/Egr-1- and JNK/AP-1-mediated transactivation of TF promoter activity, leading to downregulation of TF expression and activity induced by inflammatory mediators. Wog targeting pathological TF expression without affecting its basal level may be a safer templet in the development of anticoagulant agent for cardiovascular thrombotic diseases related to atherothrombosis.

Quercetin Inhibits the Production of IL-1ß-Induced Inflammatory Cytokines and Chemokines in ARPE-19 Cells via the MAPK and NF-κB Signaling Pathways.

Quercetin, a bioflavonoid derived from vegetables and fruits, exerts anti-inflammatory effects in various diseases. Our previous study revealed that quercetin could suppress the expression of matrix metalloprotease-9 (MMP-9) and intercellular adhesion molecule-1 (ICAM-1) to achieve anti-inflammatory effects in tumor necrosis factor-α (TNF-α)-stimulated human retinal pigment epithelial (ARPE-19) cells. The present study explored whether quercetin can inhibit the interleukin-1ß (IL-1ß)-induced production of inflammatory cytokines and chemokines in ARPE-19 cells. Prior to stimulation by IL-1ß, ARPE-19 cells were pretreated with quercetin at various concentrations (2.5-20 µM). The results showed that quercetin could dose-dependently decrease the mRNA and protein levels of ICAM-1, IL-6, IL-8 and monocyte chemoattractant protein-1 (MCP-1). It also attenuated the adherence of the human monocytic leukemia cell line THP-1 to IL-1ß-stimulated ARPE-19 cells. We also demonstrated that quercetin inhibited signaling pathways related to the inflammatory process, including phosphorylation of mitogen-activated protein kinases (MAPKs), inhibitor of nuclear factor κ-B kinase (IKK)α/ß, c-Jun, cAMP response element-binding protein (CREB), activating transcription factor 2 (ATF2) and nuclear factor (NF)-κB p65, and blocked the translocation of NF-κB p65 into the nucleus. Furthermore, MAPK inhibitors including an extracellular signal-regulated kinase (ERK) 1/2 inhibitor (U0126), a p38 inhibitor (SB202190) and a c-Jun N-terminal kinase (JNK) inhibitor (SP600125) decreased the expression of soluble ICAM-1 (sICAM-1), but not ICAM-1. U0126 and SB202190 could inhibit the expression of IL-6, IL-8 and MCP-1, but SP600125 could not. An NF-κB inhibitor (Bay 11-7082) also reduced the expression of ICAM-1, sICAM-1, IL-6, IL-8 and MCP-1. Taken together, these results provide evidence that quercetin protects ARPE-19 cells from the IL-1ß-stimulated increase in ICAM-1, sICAM-1, IL-6, IL-8 and MCP-1 production by blocking the activation of MAPK and NF-κB signaling pathways to ameliorate the inflammatory response.

Anti-inflammatory property of quercetin through downregulation of ICAM-1 and MMP-9 in TNF-α-activated retinal pigment epithelial cells.

Quercetin is a flavonoid polyphenolic compound present in fruits and vegetables that has proven anti-inflammatory activity. The goal of the present investigation was to investigate the effects of quercetin on tumor necrosis factor-α (TNF-α)-induced inflammatory responses via the expression of ICAM-1 and MMP-9 in human retinal pigment epithelial cells (ARPE-19 cells). Real-time PCR, gelatin zymography, and Western blot analysis showed that TNF-α induced the expression of ICAM-1 and MMP-9 protein and mRNA in a time-dependent manner. These effects were attenuated by pretreatment of ARPE-19 cells with quercetin. Quercetin inhibited the TNF-α-induced phosphorylation of PKCδ, JNK1/2, ERK1/2. Quercetin, rottlerin, SP600125 and U0126 attenuated TNF-α-stimulated c-Jun phosphorylation and AP-1-Luc activity. Pretreatment with quercetin, rottlerin, SP600125, or Bay 11-7082 attenuated TNF-α-induced NF-κB (p65) phosphorylation, translocation and RelA/p65-Luc activity. TNF-α significantly increased MMP-9 promoter activity and THP-1 cell adherence, and these effects were attenuated by pretreatment with quercetin, rottlerin, SP600125, U0126, tanshinone IIA or Bay 11-7082. These results suggest that quercetin attenuates TNF-α-induced ICAM-1 and MMP-9 expression in ARPE-19 cells via the MEK1/2-ERK1/2 and PKCδ-JNK1/2-c-Jun or NF-κB pathways.

Use of Chinese Herbal Medicine Improves Chemotherapy-Induced Thrombocytopenia among Gynecological Cancer Patients: An Observational Study.

BACKGROUND: Chemotherapy-induced thrombocytopenia (CIT) is a serious complication among patients with gynecological malignancies, yet management options are limited. This study aimed at reporting the potential of the Chang Gung platelet elevating formula (CGPEF), a prescription with a fixed proportion of Chinese herbs, for improving CIT among gynecologic cancer patients. MATERIALS: From 1/1/2007 to 31/12/2009, a total of 23 patients with two consecutive CIT episodes (≤ 100×103 /µL) (last cycle: C0; index cycle: C1) received the CGPEF from the nadir of platelet count of C1 and through the subsequent chemotherapy cycles (C2 and beyond). The CGPEF was taken orally four times a day. The evolution of platelet counts of 18 patients after administration of CGPEF was analyzed (2 patients had different chemotherapy regimens after CGPEF, two patients discontinued CGPEF due to the flavor and the amount of CGPEF, and one patient had no further chemotherapy). RESULTS: Most of the patients had recurrent ovarian cancer (11/18, 61%) with a median of 2.5 previous chemotherapy regimens, and carboplatin-based regimens were the most commonly used for these patients (13/18, 72%). The trend of successive CIT could be reversed after taking CGPEF. Also, the platelet nadir was higher after CGPEF treatment (16.5×103/µL versus 32×103/µL, before and after CGPEF treatment, resp., p = 0.002). Moreover, the chemotherapy interval decreased from 30.5 days to 24 days. No thrombocytosis, clinical bleeding, thromboembolism, or other adverse events were found among these patients. CONCLUSIONS: The CGPEF is worthy of further large-scale, well-designed clinical trials for CIT among gynecological cancer patients.

Protective Effects of Casticin From Vitex trifolia Alleviate Eosinophilic Airway Inflammation and Oxidative Stress in a Murine Asthma Model.

Casticin has been isolated from Vitex trifolia and found to have anti-inflammatory and anti-tumor properties. We also previously discovered that casticin can reduce pro-inflammatory cytokines and ICAM-1 expression in inflammatory pulmonary epithelial cells. In the present study, we evaluated whether casticin reduced airway hyper-responsiveness (AHR), airway inflammation, and oxidative stress in the lungs of a murine asthma model and alleviated inflammatory and oxidative responses in tracheal epithelial cells. Female BALB/c mice were randomly divided into five groups: normal controls, ovalbumin (OVA)-induced asthma, and OVA-induced asthma treated with intraperitoneal injection of casticin (5 or 10 mg/kg) or prednisolone (5 mg/kg). Casticin reduced AHR, goblet cell hyperplasia, and oxidative responses in the lungs of mice with asthma. Mechanistic studies revealed that casticin attenuated the levels of Th2 cytokine in bronchoalveolar lavage fluids and regulated the expression of Th2 cytokine and chemokine genes in the lung. Casticin also significantly regulated oxidative stress and reduced inflammation in the lungs of mice with asthma. Consequently, inflammatory tracheal epithelial BEAS-2B cells treated with casticin had significantly suppressed levels of pro-inflammatory cytokines and eotaxin, and reduced THP-1 monocyte cell adherence to BEAS-2B cells via suppressed ICAM-1 expression. Thus, casticin is a powerful immunomodulator, ameliorating pathological changes by suppressing Th2 cytokine expression in mice with asthma.

Activation of the monocytic α7 nicotinic acetylcholine receptor modulates oxidative stress and inflammation-associated development of coronary artery spasm via a p38 MAP-kinase signaling-dependent pathway.

OBJECTIVE: Smoking and high-sensitivity C-reactive protein (hs-CRP) are risk factors for coronary artery spasm (CAS), which is characterized by the increased interleukin-6 (IL-6) level and monocyte counts; however, limited data are available regarding the role of cigarette-embedded nicotine in the modulation of monocytic inflammatory activity in CAS. APPROACH: We investigated and elucidated the putative roles and associations of nicotine, monocytic IL-6, α7 nicotinic acetylcholine receptor (α7-nAChR), and CRP in CAS development. RESULTS: We demonstrated that a significantly increased α7-nAChR (p = 0.001) and IL-6 (p = 0.0036) messenger RNA (mRNA) expression in the serum of patients with CAS. Serum hs-CRP levels exhibited a strong positive correlation with the monocytic mRNA expression of α7-nAChR (r = 0.71, p < 0.001) and IL-6 (r = 0.49, p = 0.006). The α7-nAChR and IL-6 expression levels of the CAS group were also positively correlated (r = 0.63, p < 0.001). Compared with the untreated controls, THP-1 cells and patient-derived monocytes treated with different concentrations of CRP displayed significantly increased expression levels of α7-nAChR mRNA and protein (p = 0.0054), in a dose-dependent manner. We also demonstrated that compared with the IL-6 expression elicited by CRP alone (p = 0.0489), the CRP-induced rise in monocytic IL-6 mRNA and protein expression in the presence of nicotine (p = 0.0002), is mediated by α7-nAChR activation and the deregulation of the human p38 mitogen-activated protein kinases (MAPK) signaling pathway. CONCLUSIONS: Our data demonstrate that the elevated monocytic IL-6 and α7-nAChR mRNA and protein expression levels are associated with the interaction between nicotine and CRP positively modulates CAS development. Our study suggests the potential role of α7-nAChR mRNA and/or protein expression as a diagnostic biomarker for CAS.

Indigo naturalis and its component tryptanthrin exert anti-angiogenic effect by arresting cell cycle and inhibiting Akt and FAK signaling in human vascular endothelial cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Indigo naturalis has been used to treat inflammatory diseases and dermatosis, including psoriasis, since thousands of years in China. It has been proven effective in our previous clinical studies on treating psoriasis, but the active component and the mechanism of how indigo naturalis working still needs to be clarified. Since the dysregulated angiogenesis is known to play an important role in the pathogenesis of psoriasis, the anti-angiogenic effect of indigo naturalis and tryptanthrin, a pure component of indigo naturalis, was investigated. MATERIALS AND METHODS: The in vivo angiogenesis was studied by chick chorioallantoic membrane assay. The in vitro studies were performed using human vascular endothelial cells. Cell viability was determined by MTT assay. Cell cycle distribution was revealed by flow cytometry. The cellular messenger (m)RNA or protein expression level was analyzed by real-time RT-PCR or Western blot, respectively. Transwell filter migration assay and matrix gel-induced tube formation method were applied to examine the angiogenic potential. RESULTS: Indigo naturalis significantly inhibited the in vivo vascular endothelial growth factor (VEGF)-induced angiogenesis, as well as tryptanthrin. In vitro studies confirmed that indigo naturalis and tryptanthrin reduced the number of viable vascular endothelial cells. Tryptanthrin resulted in a cell cycle arrest and dose-dependently decreased the expressions of cyclin A, cyclin B, cyclin dependent kinase(CDK) 1 and 2, but not cyclin D and cyclin E, at both the mRNA and protein levels. The migration and tube formation of vascular endothelial cells were significantly inhibited by tryptanthrin in a dose-dependent manner. Result also showed that tryptanthrin could reduce the phosphorylated levels of both protein kinase B (PKB or Akt) and focal adhesion kinase (FAK). CONCLUSIONS: All together, these results demonstrated the anti-angiogenic effect of tryptanthrin, the acting component of indigo naturalis and revealed the underlying mechanism by inhibiting the cell cycle progression, cell migration and tube formation, likely mediated through blocking the Akt and FAK pathways.

Estrogen receptor α (ERα) mediates 17ß-estradiol (E2)-activated expression of HBO1.

BACKGROUND: HBO1 (histone acetyltransferase binding to ORC1) is a histone acetyltransferase (HAT) which could exert oncogenic function in breast cancer. However, the biological role and underlying mechanism of HBO1 in breast cancer remains largely unknown. In the current study, we aimed to investigate the role of HBO1 in breast cancer and uncover the underlying molecular mechanism. METHODS: Immunohistochemistry was applied to detect HBO1 protein expression in breast cancer specimens (n=112). The expression of protein level was scored by integral optical density (IOD) for further statistical analyses using SPSS. Real-time PCR was used to simultaneously measure mRNA levels of HBO1. The HBO1 protein expression in breast cancer cells was confirmed by western blot. RESULTS: HBO1 was highly expressed in breast cancer tissues and significantly correlated with estrogen receptor α (ERα) (p<0.001) and progestational hormone (PR) (p=0.002). HBO1 protein level also correlated positively with histology grade in ERα positive tumors (p=0.016) rather than ERα negative tumors. 17ß-estradiol (E2) could upregulate HBO1 gene expression which was significantly inhibited by ICI 182,780 or ERα RNAi. E2-increased HBO1 protein expression was significantly suppressed by treatment with inhibitor of MEK1/2 (U0126) in T47 D and MCF-7 cells. CONCLUSIONS: HBO1 was an important downstream molecule of ERα, and ERK1/2 signaling pathway may involved in the expression of HBO1 increased by E2.