Activation of ERK1/2 occurs independently of KRAS or BRAF status in endometrial cancer and is associated with favorable prognosis

BRAF V600E and previously unidentified KRAS G12C mutations in odontogenic tumors may affect MAPK activation differently depending on tumor type

Although several types of odontogenic tumors share the same mutations in MAPK pathway genes, their effects on MAPK activation remain unclarified. This study aimed to evaluate the associations between these mutations and ERK phosphorylation in ameloblastoma and mixed odontogenic tumors (MOTs) and to analyze the expression pattern of phosphorylated ERK (p-ERK) for determining the involvement of MAPK activation in the development and progression of odontogenic tumors. Forty-three odontogenic tumors consisting of 18 ameloblastomas and 25 MOTs were analyzed for BRAF, KRAS, and NRAS mutations by Sanger sequencing. The expressions of BRAF^V600E protein and p-ERK were detected by immunohistochemistry. The associations of mutation status and p-ERK expression were statistically analyzed. In ameloblastoma cells, the effect of BRAF^V600E inhibition on MAPK activation was investigated. In benign MOTs, BRAF^V600E mutations were neither expressed at the protein level nor associated with p-ERK expression. In contrast, BRAF^V600E -mutant ameloblastic fibrosarcoma showed co-expression of BRAF V600E protein and p-ERK, especially in the sarcomatous component. In ameloblastoma, p-ERK was predominantly expressed in the tumor periphery showing a significant correlation with BRAF^V600E mutations, and in vitro BRAF^V600E inhibition decreased ERK phosphorylation. KRAS^G12C mutations, previously unidentified in odontogenic tumors, were detected in one case each of benign MOT and ameloblastoma; only the latter was high-p-ERK. In conclusion, unlike in benign MOTs, BRAF^V600E and KRAS^G12C mutations lead to MAPK activation in ameloblastoma, suggesting their role as therapeutic targets. p-ERK intratumoral heterogeneity indicates that MAPK pathway activation may be associated with sarcomatous proliferation of ameloblastic fibrosarcoma and infiltrative behavior of ameloblastoma. This article is protected by copyright. All rights reserved.

Histone methyltransferase SETD2: a potential tumor suppressor in solid cancers

Epigenetic regulation plays an important role in the occurrence, development and treatment of malignant tumors; and a great deal of attention has been paid to the histone methylation level in recent years. As a 230-kD epigenetic regulator, the histone H3 lysine 36 histone (H3K36) methyltransferase SETD2 is a key enzyme of the nuclear receptor SET domain-containing (NSD) family, which is associated with a specific hyperphosphorylated domain, a large subunit of RNA polymerase II (RNAPII), named RNAPII subunit B1 (RPB1), and SETD2 which methylates the ly-36 position of dimethylated histone H3 (H3K36me2) to generate trimethylated H3K36 (H3K36me3). SETD2 is involved in various cellular processes, including transcriptional regulation, DNA damage repair, non-histone protein-related functions and some other processes. Great efforts of high-throughput sequencing have revealed that SETD2 is mutated or its function is lost in a range of solid cancers, including renal cancer, gastrointestinal cancer, lung cancer, pancreatic cancer, osteosarcoma, and so on. Mutation, or functional loss, of the SETD2 gene produces dysfunction in corresponding tumor tissue proteins, leading to tumorigenesis, progression, chemotherapy resistance, and unfavorable prognosis, suggesting that SETD2 possibly acts as a tumor suppressor. However, its underlying mechanism remains largely unexplored. In the present study, we summarized the latest advances of effects of SETD2 expression at the mRNA and protein levels in solid cancers, and its potential molecular and cellular functions as well as clinical applications were also reviewed.

BKCa participates in E2 inducing endometrial adenocarcinoma by activating MEK/ERK pathway

Background

The large-conductance, voltage-gated, calcium (Ca (2+))-activated potassium channel (BKCa) plays an important role in regulating Ca (2+) signaling and cell physiological function, and is aberrantly expressed in some types of cancers. The present study focuses on identifying the oncogenic potential and clinical significance of BKCa in endometrial adenocarcinoma, as well as exploring the mechanistic relevance by 17β -estradiol (E2) inducing aberrant activation of MEK1/2 and ERK1/2 via BKCa.

Methods

The expression of BKCa, ERK1/2 and p-ERK1/2 were examined by immunohistochemical staining in 263 cases, including 185 primary types I endometrial cancer tissues, 38 atypical endometrial hyperplasia tissues and 40 normal endometrium tissues. Cell growth, cycle, apoptosis rate, migration and invasion was separately tested in Ishikawa cells using siRNA-BKCa and/or E2 treatment, as well as the expression of these interested proteins by western blot analysis.

Results

We showed that expression of BKCa is significantly elevated in 185 types I endometrial adenocarcinoma tissues compared to those of the normal endometrium and atypical endometrial hyperplasia tissues. Furthermore, in vitro observations revealed that down-regulation of BKCa expression inhibited cell growth by both enhancing apoptosis and blocking G1/S transition, suppressed cell migration and invasion in Ishakiwa cells, and decreased the expression of p-MEK1/2 and p-ERK1/2. Additionally, RNAi-mediated knockdown of BKCa attenuated the increased cellular growth and invasion, as well as the elevated expression of p-MEK1/2 and p-ERK1/2 proteins, induced by E2 stimulation. More importantly, the aberrant expression of BKCa and p-ERK1/2 were closely related with poor prognostic factors in type I endometrial cancer, and up-regulated expression of p-ERK1/2 was significantly associated with shorter disease-free survival (DFS) and overall survival (OS) and was an independent prognostic factor in type I endometrial cancer patients.

Conclusion

Our results demonstrated that BKCa and the key downstream effectors p-ERK1/2 could be involved in important signaling pathways in initiation and development of endometrial adenocarcinoma and may provide a new therapeutic approach for women with endometrial cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5027-9) contains supplementary material, which is available to authorized users.

The expression of ER, PR in endometrial cancer and analysis of their correlation with ERK signaling pathway

Endometrial carcinoma (EC) is a common malignant tumor in gynecology. Its incidence and development are closely associated with the levels of estrogenic and progesterone hormone. Extracellular signal-regulated kinase (ERK) signaling pathway abnormity is associated with a variety of tumors. This study detected estrogen receptor (ER), progesterone receptor (PR), ERK1, and ERK2 expression in EC and analyzed their correlations. A total of 40 EC patients in our hospital were selected as test group, while another 40 healthy volunteers were enrolled as control group. ER, PR, ERK1, and ERK2 expression in EC tissue, para-carcinoma tissue, and normal endometrial tissue were detected by immunohistochemistry and Western blot. The positive rate of ER, PR, ERK1, and ERK2 in the test group was 50%, 40%, 60%, and 65%, respectively, which were significantly higher than those in the control (P< 0.05). ER, PR, ERK1, and ERK2 protein expressions in EC cell were significantly higher than those in the control (P< 0.05). ERK1 and ERK2 presented positive correlation with ER and PR (P< 0.05). In conclusion, EC patients presented higher expressions of ER, PR, which were correlated with higher levels of ERK1 and ERK2, suggesting they might be involved in the pathogenesis of EC.

Acquired SETD2 mutation and impaired CREB1 activation confer cisplatin resistance in metastatic non-small cell lung cancer

Resistance to chemotherapy remains a critical barrier to effective cancer treatment. Although cisplatin is one of the most commonly used chemotherapeutic agents in the treatment of non-small cell lung cancer (NSCLC), mechanisms of resistance to this drug are not fully understood. Here, we report a novel cisplatin-resistance mechanism involving SET Domain Containing 2 (SETD2), a histone H3 lysine 36 (H3K36) trimethyltransferase, and cAMP-responsive element-binding protein 1 (CREB1). A549 cells selected in vivo to give brain metastases exhibited cisplatin resistance and decreased expression of phosphorylated CREB1. Next-generation sequencing (NGS) analysis identified a missense mutation in SETD2 (p.T1171K), and we demonstrated that SETD2-mediated trimethylation of H3K36 (H3K36me3) and CREB1 phosphorylation are critical for cellular sensitivity to cisplatin. Moreover, we showed that suppression of SETD2 or CREB1 and ectopic expression of mutant SETD2 conferred cisplatin resistance through inhibition of H3K36me3 and ERK activation in NSCLC cells. Our results provide evidence that SETD2 and CREB1 contribute to cisplatin cytotoxicity via regulation of the ERK signaling pathway, and their inactivation may lead to cisplatin resistance.

Hesperidin promotes programmed cell death by downregulation of nongenomic estrogen receptor signalling pathway in endometrial cancer cells

Endometrial carcinoma (EC) is the most common malignant gynecologic tumor in women. EC is thought to be caused by increasing estrogen levels relative to progesterone in the body. Hesperidin (Hsd), a biologically active flavonoid, could be extracted from Citrus species. It has been recently shown that Hsd could exert anticarcinogenic properties in different cancer types. However, the effects of Hsd and its molecular mechanisms on EC remain unclear. In this study, the antiproliferative, apoptotic and genomic effects of Hsd in EC and its underlying mechanisms were identified. We found that Hsd significantly suppressed the proliferation of EC cells in dose and time dependent manner. Mechanistic studies showed that Hsd could contribute apoptosis by inducing externalization of phosphatidyl serine (PS), caspase-3 activity and loss of mitochondrial membrane (MMP). Furthermore, we examined that Hsd could also significantly upregulate the expression of proapoptotic Bax subgroup genes (Bax and Bik) while downregulating the anti-apoptotic protein Bcl-2 in EC cell lines. According to GO enrichment and KEGG pathway analysis of differentially expressed genes in Hsd treated EC cells, we identified that Hsd could promote cell death via downregulation of estrogen receptor I (ESRI) that was directly related to ERK/MAPK pathway. Taken together, our study first showed that Hsd could be an antiestrogenic compound that could modulate nongenomic estrogen receptor signaling through inhibition of EC cell growth. Our findings may provide us a novel growth inhibitory agent for EC treatment after verifying its molecular mechanism with in vivo studies.

Inhibition of nuclear factor-kappa B enhances the tumor growth of ovarian cancer cell line derived from a low-grade papillary serous carcinoma in p53-independent pathway

Background

NF-kB can function as an oncogene or tumor suppressor depending on cancer types. The role of NF-kB in low-grade serous ovarian cancer, however, has never been tested. We sought to elucidate the function of NF-kB in the low-grade serous ovarian cancer.

Methods

The ovarian cancer cell line, HOC-7, derived from a low-grade papillary serous carcinoma. Introduction of a dominant negative mutant, IkBαM, which resulted in decrease of NF-kB function in ovarian cancer cell lines. The transcription ability, tumorigenesis, cell proliferation and apoptosis were observed in derivative cell lines in comparison with parental cells.

Results

Western blot analysis indicated increased expression of the anti-apoptotic proteins Bcl-xL and reduced expression of the pro-apoptotic proteins Bax, Bad, and Bid in HOC-7/IĸBαM cell. Further investigations validate this conclusion in KRAS wildtype cell line SKOV3. Interesting, NF-kB can exert its pro-apoptotic effect by activating mitogen-activated protein kinase (MAPK) phosphorylation in SKOV3 ovarian cancer cell, whereas opposite changes detected in p-MEK in HOC-7 ovarian cancer cell, the same as some chemoresistant ovarian cancer cell lines. In vivo animal assay performed on BALB/athymic mice showed that injection of HOC-7 induced subcutaneous tumor growth, which was completely regressed within 7 weeks. In comparison, HOC-7/IĸBαM cells caused sustained tumor growth and abrogated tumor regression, suggesting that knock-down of NF-kB by IĸBαM promoted sustained tumor growth and delayed tumor regression in HOC-7 cells.

Conclusion

Our results demonstrated that NF-kB may function as a tumor suppressor by facilitating regression of low grade ovarian serous carcinoma through activating pro-apoptotic pathways.

Activation of MEK1/2-ERK1/2 signaling during NNK-induced lung carcinogenesis in female A/J mice

The extracellular signal‐regulated kinase 1/2 (ERK1/2) signaling pathway is activated by several growth factors and mitogens, and upregulation has been noted in many human cancers, including examples in the lung. In this study, to study the association of ERK1/2 activation with mutation of Kras encoding an upstream activator of ERK1/2 in lung premalignant lesions, we immunohistochemically examined expression of phosphorylated forms of ERK1/2 (pERK1/2) and MAP/ERK kinase 1/2 (pMEK1/2) proteins and correlation between ERK activation and mutation of Kras encoding an upstream activator of ERK1/2, in a mouse lung carcinogenesis model. Female 7‐week‐old A/J mice were administered a single dose of 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK), then maintained without additional treatment until sacrifice at week 52. Histopathologically, adenocarcinomas, adenomas and hyperplasias were observed in the lung. pMEK1/2 was expressed mostly in the cell cytoplasm in all three. In contrast, pERK1/2‐positive cells were also relatively rare in any histological types as compared with level of pMEK1/2 expression. However, pERK1/2‐positive cells in adenocarcinoma were still markedly more common than in hyperplasias and adenomas (~5‐fold, ~4‐fold; P < 0.01). Activating mutations of Kras gene at codons 12, 13 and 61 were detected in the majority of adenomas and adenocarcinomas, but without any significant relation to pERK1/2 expression. These results suggest that activation of ERK1/2 plays a key role in malignant transformation during lung carcinogenesis featuring Kras mutaion. Activation of ERK1/2 in lung premalignant lesions was little regardless of the mutation of Kras, and ERK1/2 activation in NNK‐induced mouse lung carcinogenesis may be regulated not only by Kras mutation but also other signaling pathway or regulatory factor.

Endometrial tumour BRAF mutations and MLH1 promoter methylation as predictors of germline mismatch repair gene mutation status: a literature review

Colorectal cancer (CRC) that displays high microsatellite instability (MSI-H) can be caused by either germline mutations in mismatch repair (MMR) genes, or non-inherited transcriptional silencing of the MLH1 promoter. A correlation between MLH1 promoter methylation, specifically the 'C' region, and BRAF V600E status has been reported in CRC studies. Germline MMR mutations also greatly increase risk of endometrial cancer (EC), but no systematic review has been undertaken to determine if these tumour markers may be useful predictors of MMR mutation status in EC patients. Endometrial cancer cohorts meeting review inclusion criteria encompassed 2675 tumours from 20 studies for BRAF V600E, and 447 tumours from 11 studies for MLH1 methylation testing. BRAF V600E mutations were reported in 4/2675 (0.1%) endometrial tumours of unknown MMR mutation status, and there were 7/823 (0.9%) total sequence variants in exon 11 and 27/1012 (2.7%) in exon 15. Promoter MLH1 methylation was not observed in tumours from 32 MLH1 mutation carriers, or for 13 MSH2 or MSH6 mutation carriers. MMR mutation-negative individuals with tumour MLH1 and PMS2 IHC loss displayed MLH1 methylation in 48/51 (94%) of tumours. We have also detailed specific examples that show the importance of MLH1 promoter region, assay design, and quantification of methylation. This review shows that BRAF mutations occurs so infrequently in endometrial tumours they can be discounted as a useful marker for predicting MMR-negative mutation status, and further studies of endometrial cohorts with known MMR mutation status are necessary to quantify the utility of tumour MLH1 promoter methylation as a marker of negative germline MMR mutation status in EC patients.

Complex interactions between the components of the PI3K/AKT/mTOR pathway, and with components of MAPK, JAK/STAT and Notch-1 pathways, indicate their involvement in meningioma development

We investigated the significance of PI3K/AKT/mTOR pathway and its interactions with MAPK, JAK/STAT and Notch pathways in meningioma progression. Paraffin-embedded tissue from 108 meningioma patients was analysed for the presence of mutations in PIK3CA and AKT1. These were correlated with the expression status of components of the PI3K/AKT/mTOR pathway, including p85α and p110γ subunits of PI3K, phosphorylated (p)-AKT, p-mTOR, p-p70S6K and p-4E-BP1, as well as of p-ERK1/2, p-STAT3 and Notch-1, clinicopathological data and patient survival. A mutation in PIK3CA or AKT1 was found in around 9 % of the cases. Higher grade meningiomas displayed higher nuclear expression of p-p70S6K; higher nuclear and cytoplasmic expression of p-4E-BP1 and of Notch-1; lower cytoplasmic expression of p85αPI3K, p-p70S6K and p-ERK1/2; and lower PTEN Histo-scores (H-scores). PTEN H-score was inversely correlated with recurrence probability. In univariate survival analysis, nuclear expression of p-4E-BP1 and absence of p-ERK1/2 expression portended adverse prognosis, whereas in multivariate survival analysis, p-ERK1/2 expression emerged as an independent favourable prognostic factor. Treatment of the human meningioma cell line HBL-52 with the PI3K inhibitor LY294002 resulted in reduction of p-AKT, p-p70S6K and p-ERK1/2 protein levels. The complex interactions established between components of the PI3K/AKT/mTOR pathway, or with components of the MAPK, JAK/STAT and Notch-1 pathways, appear to be essential for facilitating and fuelling meningioma progression.

Immunolocalization of ERK1/2 and p-AKT in normal endometrium, endometrial hyperplasia, and early and advanced stage endometrioid endometrial adenocancer and their prognostic significance in malignant group

OBJECTIVE

To analyze the expression patterns of extracellular signal-regulated kinase (ERK1/2) and phosphorylated (p)-AKT in the tissues of non-pathologic endometrium, endometrial hyperplasia, and early and advanced stage endometrioid endometrial adenocancer using indirect immunohistochemistry, and also to investigate the effect of ERK1/2 and p-AKT expression patterns on prognosis in endometrioid adenocancer.

STUDY DESIGN

Immunolocalization of ERK1/2 and p-AKT was examined in six different types of endometrial tissues: proliferative endometrium (PE; n=10, 11.2%), secretuar endometrium (SE; n=10, 11.2%), simple hyperplasia (SH; n=15, 16.9%), complex hyperplasia (CH; n=3, 3.4%) and atypical complex hyperplasia (ACH; n=10, 11.2%), which were obtained from endometrial biopsies, curettage materials, and hysterectomy specimens and classified as the benign group; and both early stage endometrioid (n=21, 23.6%) and advanced stage endometrioid adenocancer (AC; n=20, 22.5%), which were obtained from complete surgical staging materials and classified as the malignant group. All specimens were fixed in 10% formalin and processed using routine paraffin protocols. Immunostaining intensities were evaluated as negative or weak (assigned as low expression) and moderate or strong (assigned as high expression).

RESULTS

In the malignant group, 23 of 41 patients (56.1%) had high ERK1/2 and p-AKT expression, whereas only three of 48 patients in the benign group (6.3%) had high ERK1/2 and p-AKT expression (P<0.0001 and P<0.0001, respectively). p-AKT expression was significantly higher in women with positive lymph nodes (OR 9.0; 95% CI: 1.2-100.0; P=0.03). Higher expression of p-AKT was significantly associated with poor progression-free survival (PFS) and overall survival (OS). In contrast, ERK1/2 expression was not associated with PFS or OS.Conclusions ERK1/2 and p-AKT can be useful in the differential diagnosis of benign vs. malignant endometrial lesions, as well as early vs. advanced stage endometrioid endometrial adenocancer. Additionally, higher p-AKT expression could be used as a marker of poor prognosis in the management of patients with endometrioid endometrial adenocancer.

Extracellular signal-regulated kinase (ERK) expression and activation in mobile tongue squamous cell carcinoma: associations with clinicopathological parameters and patients survival

Extracellular signal-regulated kinase (ERK) has been considered as a critical regulator of diverse cellular processes such as proliferation, survival and motility, being implicated in the malignant transformation in several tissue types. The present study aimed to evaluate the clinical significance of total ERK1 (t-ERK1) and phosphorylated ERK1/2 (p-ERK1/2) protein expression in mobile tongue squamous cell carcinoma (SCC). t-ERK1 and p-ERK1/2 protein expression in tumour cells and infiltrating the tumour microenvironment lymphoid cells was assessed immunohistochemically on 47 mobile tongue SCC tissue samples and was analyzed in relation with clinicopathological characteristics, overall and disease-free patients' survival. Enhanced nuclear t-ERK1 and p-ERK1/2 expression in tumour cells was associated with the absence of perineural invasion (p = 0.043) and shorter overall patients' survival (log-rank test, p = 0.028), respectively. Enhanced t-ERK1 expression in infiltrating lymphoid cells was significantly associated with female gender, absence of vascular and perineural invasion, lymph node metastases and early depth of invasion (p = 0.008, p = 0.019, p = 0.011, p = 0.036 and p = 0.001, respectively), as well as with longer disease-free survival times (log-rank test, p = 0.038). Enhanced p-ERK1/2 expression in infiltrating lymphoid cells was significantly associated with the presence of vascular invasion and lymph node metastases (p = 0.019 and p = 0.004, respectively) and shorter overall patients' survival (log-rank test, p = 0.013). In multivariate analysis, p-ERK1/2 expression in tumour cells and infiltrating lymphoid cells was identified as independent prognostic factors of overall survival (Cox regression analysis, p = 0.045 and p = 0.032, respectively). The present study supported evidence that ERK signalling pathway may exert a potential role in the pathophysiological aspects of the mobile tongue SCC, presenting also potential utility as a biomarker for patients' survival and reinforcing the development of novel anti-cancer therapies targeting ERK signalling cascade in this type of human malignancy.

Molecular characterization of CD133+ cancer stem-like cells in endometrial cancer

A small subset of cells with CD133 expression is thought to have increased chemoresistance and tumorigenicity, features of cancer stem cells (CSCs); the molecular mechanisms by which these properties arise remain unclear. We characterized CD133+ endometrial cancer cells based on microarray analyses of Ishikawa cells. Of the genes upregulated in CD133+ cells compared with CD133- cells, we noted several key factors involved in the aggressive behavior of cells, including ABCG2 and matrix metalloproteinase (MMP). Flow cytometric analyses identified a side-cell population (SP) with CSC features in Ishikawa cells, and they were found to be more enriched in CD133+ cells than CD133- cells. In particular, CD133+/SP cells exhibited higher proliferative and colony‑forming activity than CD133+/non-SP cells. Matrigel invasion assay revealed that CD133+ cells have enhanced invasive capacity with elevated MT1-MMP expression. siRNA‑based knockdown of MT1-MMP largely abolished the invasive capacity of CD133+ cells, but not CD133- cells due to low levels of constitutive MT1-MMP1 expression. These findings demonstrate that increased chemoresistance and tumorigenic potential of CD133+ cells are at least partly attributed to an enriched SP fraction as well as increased MMP-1 expression. These results will be of assistance in the establishment of molecular target therapy to CSCs in endometrial cancer.

Human breast tumor cells are more resistant to cardiac glycoside toxicity than non-tumorigenic breast cells

Cardiotonic steroids (CTS), specific inhibitors of Na,K-ATPase activity, have been widely used for treating cardiac insufficiency. Recent studies suggest that low levels of endogenous CTS do not inhibit Na,K-ATPase activity but play a role in regulating blood pressure, inducing cellular kinase activity, and promoting cell viability. Higher CTS concentrations inhibit Na,K-ATPase activity and can induce reactive oxygen species, growth arrest, and cell death. CTS are being considered as potential novel therapies in cancer treatment, as they have been shown to limit tumor cell growth. However, there is a lack of information on the relative toxicity of tumor cells and comparable non-tumor cells. We have investigated the effects of CTS compounds, ouabain, digitoxin, and bufalin, on cell growth and survival in cell lines exhibiting the full spectrum of non-cancerous to malignant phenotypes. We show that CTS inhibit membrane Na,K-ATPase activity equally well in all cell lines tested regardless of metastatic potential. In contrast, the cellular responses to the drugs are different in non-tumor and tumor cells. Ouabain causes greater inhibition of proliferation and more extensive apoptosis in non-tumor breast cells compared to malignant or oncogene-transfected cells. In tumor cells, the effects of ouabain are accompanied by activation of anti-apoptotic ERK1/2. However, ERK1/2 or Src inhibition does not sensitize tumor cells to CTS cytotoxicity, suggesting that other mechanisms provide protection to the tumor cells. Reduced CTS-sensitivity in breast tumor cells compared to non-tumor cells indicates that CTS are not good candidates as cancer therapies.

Glycogen synthase kinase 3β inhibition as a therapeutic approach in the treatment of endometrial cancer

Alternative strategies beyond current chemotherapy and radiation therapy regimens are needed in the treatment of advanced stage and recurrent endometrial cancers. There is considerable promise for biologic agents targeting the extracellular signal-regulated kinase (ERK) pathway for treatment of these cancers. Many downstream substrates of the ERK signaling pathway, such as glycogen synthase kinase 3β (GSK3β), and their roles in endometrial carcinogenesis have not yet been investigated. In this study, we tested the importance of GSK3β inhibition in endometrial cancer cell lines and in vivo models. Inhibition of GSK3β by either lithium chloride (LiCl) or specific GSK3β inhibitor VIII showed cytostatic and cytotoxic effects on multiple endometrial cancer cell lines, with little effect on the immortalized normal endometrial cell line. Flow cytometry and immunofluorescence revealed a G2/M cell cycle arrest in both type I (AN3CA, KLE, and RL952) and type II (ARK1) endometrial cancer cell lines. In addition, LiCl pre-treatment sensitized AN3CA cells to the chemotherapy agent paclitaxel. Administration of LiCl to AN3CA tumor-bearing mice resulted in partial or complete regression of some tumors. Thus, GSK3β activity is associated with endometrial cancer tumorigenesis and its pharmacologic inhibition reduces cell proliferation and tumor growth.

BRAF V600E Mutations in Endometrial Adenocarcinoma

The BRAF V600E somatic mutation is recognized as an oncogenic driver of many human cancers involving the MAPK/ERK pathway. Colorectal and lung cancers associated with the BRAF V600E mutation often demonstrated mucinous morphology. This study hypothesized that the BRAF V600E mutation may be associated with mucinous morphology in endometrial cancer and aimed to investigate its prevalence in mucinous (endometrial) carcinoma (MC) and endometrioid adenocarcinoma with significant mucinous differentiations (ECMD) (>10% neoplastic cells). Twenty-eight cases of endometrial cancer were selected, including 17 (60.7%) cases of MC or ECMD. All patients were Caucasian with age ranging from 50 to 87 years old (median 65). Genomic DNA was extracted from formalin-fixed paraffin-embedded tumor tissue and subjected to both real-time mutant allele-specific amplification polymerase chain reaction (PCR) and PCR amplification, followed by direct sequencing. Three (3/28, 10.7%) BRAF V600E mutations were detected by real-time mutant allele-specific amplification PCR and confirmed by direct sequencing. Two of 3 cases positive for BRAF V600E mutation were ECMDs with "surface epithelial changes." KRAS mutations were found in 9 cases (32.1%), none with BRAF mutation. This is the first report of BRAF V600E mutation in endometrial cancer, indicating that it may contribute to tumorigenesis of endometrial cancer, although at a low frequency compared with KRAS mutations.

KRAS and MAPK1 gene amplification in type II ovarian carcinomas

In this study, we examined the clinical significance of KRAS and MAPK1 amplification and assessed whether these amplified genes were potential therapeutic targets in type II ovarian carcinoma. Using fluorescence in situ hybridization, immunohistochemistry, and retrospectively collected clinical data, KRAS and MAPK1 amplifications were identified in 9 (13.2%) and 5 (7.4%) of 68 type II ovarian carcinoma tissue samples, respectively. Interestingly, co-amplification of KRAS and MAPK1 seemed to be absent in the type II ovarian carcinomas tested, except one case. Active phospho-ERK1/2 was identified in 26 (38.2%) out of 68 type II ovarian carcinomas and did not correlate with KRAS or MAPK1 amplification. There was no significant relationship between KRAS amplification and overall or progression-free survival in patients with type II ovarian carcinoma. However, patients with MAPK1 amplification had significantly poorer progression-free survival than patients without MAPK1 amplification. Moreover, type II ovarian carcinoma cells with concomitant KRAS amplification and mutation exhibited dramatic growth reduction following treatment with the MEK inhibitor PD0325901. These findings indicate that KRAS/MAPK1 amplification is critical for the growth of a subset of type II ovarian carcinomas. Additionally, RAS/RAF/MEK/ERK pathway-targeted therapy may benefit selected patients with type II ovarian carcinoma harboring KRAS/MAPK1 amplifications.

mTOR signaling pathway in penile squamous cell carcinoma: pmTOR and peIF4E over expression correlate with aggressive tumor behavior

PURPOSE

Penile squamous cell carcinoma is a rare neoplasm associated with a high risk of metastasis and morbidity. There are limited data on the role of the mTOR signaling pathway in penile squamous cell carcinoma carcinogenesis and tumor maintenance. We assessed a possible role for mTOR signaling pathway activation as a potential predictive biomarker of outcome and a therapeutic target for penile cancer.

MATERIAL AND METHODS

A cohort of 67 patients diagnosed with invasive penile squamous cell carcinoma from 1987 to 2010 who had known HPV status were selected for study. Tissue microarrays were constructed with 67 primary penile squamous cell carcinomas, matched normal tissues and 8 lymph node metastases. Immunohistochemical staining was performed for p53, pmTOR, pERK, p4E-BP1, eIF4E and peIF4E. Expression was evaluated using a semiquantitative H-score on a scale of 0 to 300.

RESULTS

Expression of pmTOR, p4E-BP1, eIF4E and peIF4E was increased in penile tumors compared with matched adjacent normal tissues, indicating activation of the mTOR signaling pathway in penile tumorigenesis. Over expression of pmTOR, peIF4E and p53 was significantly associated with lymph node disease. peIF4E and p53 also correlated with a poor outcome, including recurrence, metastasis or disease specific death. In contrast, pERK and p4E-BP1 were associated with lower pT stages. pmTOR and intense p53 expression was associated with HPV negative tumors.

CONCLUSIONS

Activation of mTOR signaling may contribute to penile squamous cell carcinoma progression and aggressive behavior. Targeting mTOR or its downstream signaling targets, such as peIF4E, may be a valid therapeutic strategy.

Candidate biomarkers for genetic and clinicopathological diagnosis of endometrial cancer

The recent increase in the frequency of endometrial cancer has emphasized the need for accurate diagnosis and improved treatment. The current diagnosis is still based on conventional pathological indicators, such as clinical stage, tumor differentiation, invasion depth and vascular invasion. However, the genetic mechanisms underlying endometrial cancer have gradually been determined, due to developments in molecular biology, leading to the possibility of new methods of diagnosis and treatment planning. New candidate biomarkers for endometrial cancer include those for molecular epigenetic mutations, such as microRNAs. These biomarkers may permit earlier detection of endometrial cancer and prediction of outcomes and are likely to contribute to future personalized therapy for endometrial cancer.

A phase II evaluation of gefitinib in the treatment of persistent or recurrent endometrial cancer: a Gynecologic Oncology Group study

BACKGROUND

A phase II trial was performed to evaluate the efficacy and safety of gefitinib in patients with persistent/recurrent endometrial cancer.

METHODS

Women with histologically confirmed persistent/recurrent endometrial cancer were treated with 500mg oral gefitinib daily until progression or severe toxicity, with progression-free survival (PFS) at six months as the primary endpoint. Tumor expression of total epidermal growth factor receptor (EGFR), estrogen receptor (ER), progesterone receptor A (PRA) and B (PRB), Ki67, pEGFR and activated extracellular signal-regulated kinase (pERK) were examined pre- and post-treatment. EGFR was sequenced, and serum concentrations of soluble EGFR (sEGFR) at baseline also were examined.

RESULTS

Of 29 patients enrolled, 26 were evaluable for efficacy and toxicity. Four patients experienced PFS ≥6 months, and one had a complete response which was not associated with an EGFR mutation. The concentration of sEGFR in pretreatment serum was positively correlated with overall survival (OS), but not with responsiveness to gefitinib in this small patient cohort. Expression of tumor biomarkers was not associated with PFS or OS. Co-expression of ER with PRA in primary and recurrent tumors, and pEGFR with pERK in primary tumors was observed.

CONCLUSIONS

This treatment regimen was tolerable but lacked sufficient efficacy to warrant further evaluation in this setting. The possible association between serum sEGFR concentrations and OS, and temporal changes in expression of pEGFR and pERK and the documented CR of one patient are interesting and warrant additional investigation.

ERK phosphorylation is not increased in papillary thyroid carcinomas with BRAF(V600E) mutation compared to that of corresponding normal thyroid tissues

BACKGROUND

An association between a BRAF(V600E) mutation and upregulation of mitogen-activated protein kinase (MAPK) pathways in human papillary thyroid carcinoma (PTC) tissues has not been demonstrated well outside of in vitro studies. The aims of this study were to evaluate the activation status of extracellular signal-regulated kinase 1/2 (ERK1/2) in human PTCs with BRAF(V600E) mutations compared to that of corresponding normal thyroid tissue and to determine the expressions of Raf kinase inhibitor protein (RKIP) and MAPK phosphatase 3 (MKP-3), possible regulators of ERK1/2 activation.

METHODS

We analyzed the presence of BRAF(V600E) mutation and the expressions of BRAF, total ERK, p-ERK, RKIP, and MKP-3 in 33 PTCs and corresponding normal thyroid gland tissues using western blot analysis.

RESULTS

BRAF(V600E) mutation was found in 28 (84.8%) of 33 PTCs, 96.4% (27/28) of which showed decreased p-ERK activity, while 75% (21/28) showed increased MKP-3 expression. There were significant differences in p-ERK and MKP-3 expressions between BRAF(V600E) (+) PTCs and normal thyroid glands (p < 0.001). There were no differences in expressions of BRAF, total ERK, and RKIP between PTCs and normal thyroid tissue, irrespective of the presence of BRAF(V600E) mutation.

CONCLUSIONS

In human BRAF(V600E) (+) PTCs, ERK phosphorylation is decreased compared to normal thyroid glands and the observed decrease in ERK1/2 MAPK phosphorylation in BRAF(V600E) (+) PTCs may be associated with increased MKP-3 activity.

Molecular targets and targeted therapeutics in endometrial cancer

PURPOSE OF REVIEW

Endometrial cancer is the most common gynaecological malignancy in the western world. Two clinicopathological subtypes are recognized: type I (endometrioid) and type II (nonendometrioid) carcinomas. This review describes the molecular alterations in endometrial cancer and how this knowledge is leading to the development of novel treatments in this area.

RECENT FINDINGS

Molecularly targeted agents have entered clinical trials in endometrial cancer. So far, mechanistic target of rapamycin (mTOR) inhibitors and antiangiogenic agents appear promising and are being pursued further in addition to other targeted approaches.

SUMMARY

The clinicopathological and molecular heterogeneity of endometrial cancer needs to be taken into account in the design of future clinical trials as well as the incorporation of robust biomarkers for the success of therapeutic strategies in endometrial cancer.

pERK activation in esophageal carcinomas: clinicopathological associations

MAPK (mitogen-activated protein kinase) pathway is considered a control regulator in various malignant tumors but its role in esophageal carcinomas remains elusive. In our study, we examined the possible prognostic significance of MAPK pathway in human esophageal cancer. We searched for mutations in exons 18-21 of EGFR gene, codons 12 and 13 of K-RAS gene and exon 15 of B-RAF gene by high resolution melting analysis (HRMA) and pyrosequencing in 44 esophageal carcinomas. Immunohistochemistry was performed in 29 cases in order to evaluate expression levels of pERK (extracellular-signal regulated kinase). In one laser microdissected squamous cell carcinoma, a somatic K-RAS mutation at codon 12 was detected, whereas none of the cases displayed mutations in EGFR and B-RAF genes. Elevated nuclear as well as cytoplasmic pERK expression (100% and 62% of cases respectively) was observed independently of EGFR and B-RAF mutational status. Increasing pERK nuclear and cytoplasmic expression as well as the intensity of nuclear staining was found to be significantly correlated with tumor grade in univariate and multivariate statistical analysis. Our findings depict the presence of activated ERK despite the low frequency of upstream alterations, implicating ERK activation in the acquisition of a more aggressive phenotype in esophageal cancer.

Insulin promotes proliferation, survival, and invasion in endometrial carcinoma by activating the MEK/ERK pathway

The involvement of insulin in endometrial carcinoma (EC) was investigated using radioimmunoassay, Western blot, immunoprecipitation, MTT, and Annexin V-FITC/PI assays in tissue samples and cultured cells. Serum levels of insulin, p-p52Shc, p-p46Shc, Shc·Grb2 complexes, p-MEK, p-ERK, and cyclin D1 were elevated in patients with EC. Expression of key proteins in the MEK/ERK pathway, including p-p52Shc, Shc·Grb2 complexes, p-MEK, p-ERK, and cyclin D1, was significantly higher in patients with advanced FIGO stage, high grade, and lymph-node metastasis and correlated positively with serum insulin concentration. Insulin promotes Ishikawa 3-H-12 cell proliferation, survival, and invasion, and these effects induced by insulin were significantly blocked by MEK inhibitor PD98059. Insulin thus promotes EC cell proliferation, survival, and invasion via the MEK/ERK pathway.

The genomics and genetics of endometrial cancer

Most sporadic endometrial cancers (ECs) can be histologically classified as endometrioid, serous, or clear cell. Each histotype has a distinct natural history, clinical behavior, and genetic etiology. Endometrioid ECs have an overall favorable prognosis. They are typified by high frequency genomic alterations affecting PIK3CA, PIK3R1, PTEN, KRAS, FGFR2, ARID1A (BAF250a), and CTNNB1 (β-catenin), as well as epigenetic silencing of MLH1 resulting in microsatellite instability. Serous and clear cell ECs are clinically aggressive tumors that are rare at presentation but account for a disproportionate fraction of all endometrial cancer deaths. Serous ECs tend to be aneuploid and are typified by frequent genomic alterations affecting TP53 (p53), PPP2R1A, HER-2/ERBB2, PIK3CA, and PTEN; additionally, they display dysregulation of E-cadherin, p16, cyclin E, and BAF250a. The genetic etiology of clear cell ECs resembles that of serous ECs, but it remains relatively poorly defined. A detailed discussion of the characteristic patterns of genomic alterations that distinguish the three major histotypes of endometrial cancer is reviewed herein.

ERK/pERK expression and B-raf mutations in colon adenocarcinomas: correlation with clinicopathological characteristics

BACKGROUND

Colorectal (CRC) carcinogenesis through various morphological stages has been linked to several genetic and epigenetic changes. The Raf/MEK/ERK (MAPK) signal transduction cascade is an important mediator of a number of cellular fates.

METHODS

In this study, we investigated the presence of B-raf and K-ras mutations in 94 consecutive cases of primary colon adenocarcinoma in correlation with the immunohistochemical expression of total and activated ERK and the expression of mismatch repair proteins (MMR) hMLH1 and hMSH2 as well as their correlations with standard clinicopathological parameters.

RESULTS

The immunostaining pattern for total and activated ERK was nuclear and cytoplasmic. hMLH1 and hMSH2 proteins were preserved in 45/63 (71.43%) cases and 35/53 (66.04%) cases respectively. Total ERK nuclear expression, was positively correlated with tumor stage (p = 0.049), whereas nuclear pERK expression was positively correlated with histological grade (p = 0.0113) and tumor stage (p = 0.0952), although the latter relationship was of marginal significance. DNA sequencing showed that 12 samples (12.7%) had a mutation in B-RAF Exon 15 and none in Exon 11, whereas 22 (23.4%) had a K-ras mutation. Disruption of the MAP kinase pathway-either through K-ras or B-raf mutation-was detected in 37% of all the examined cases, although the overexpression of total and activated ERK1/2 was not correlated with the mutational status of K-ras or B-raf genes. Finally, the preservation of hMLH1 or hMSH2 immunoexpression was not correlated with the presence of B-raf and/or K-ras mutations.

CONCLUSIONS

In this study, we present evidence that ERK activation occurs in a K-ras or B-raf -independent manner in the majority of primary colon cancer cases. Moreover, B-raf mutations are not associated with mismatch-repair deficiency through loss of hMLH1 or hMSH2 expression. Activated ERK could possibly be implicated in tumor invasiveness as well as in the acquisition of a more aggressive phenotype.

Significance of nuclear p-Akt in endometrial carcinogenesis: rapid translocation of p-Akt into the nucleus by estrogen, possibly resulting in inhibition of apoptosis

INTRODUCTION

Endometrial endometrioid adenocarcinoma (endometrial cancer) develops through endometrial hyperplasia caused by estrogenic hyperstimulation. Estrogen is known to activate growth factor signaling pathways, resulting in cellular proliferation, but precisely how has not been clarified. The aim of this study was to investigate the significance of estrogen and downstream factors such as the MAPK (MEK, ERK) and Akt pathways in endometrial carcinogenesis.

METHODS

The expression of p-MEK, p-ERK, and p-Akt was analyzed immunohistochemically in normal, hyperplastic, and neoplastic endometria. The estrogenic effect on p-Akt was examined using an endometrial cancer cell line (Ishikawa cells). The estrogenic effect on the apoptosis of Ishikawa cells was assessed by the TUNEL method.

RESULTS

Phospho-MEK (p-MEK) and p-ERK expression levels were similar among histological types but correlated with each other. The nuclear p-Akt labeling index (LI) was higher in cancer than in normal endometrium and hyperplasia. The nuclear p-Akt LI of well-differentiated cancer (G1) was higher than that of moderately (G2) or poorly (G3) differentiated cancers. The nuclear expression of p-Akt was correlated with that of estrogen receptor α (ER-α). The nuclear p-Akt level was significantly correlated with prognosis in cases of G1. In Ishikawa cells transfected with ERα, p-Akt was translocated into the nucleus from the cytoplasm in 1 to 3 hours after estrogenic stimulation. Further, apoptosis induced by H2O2 was inhibited by estrogen in the ER-α-positive cells.

CONCLUSIONS

The translocation of p-Akt into the nucleus by estrogen may be related to the suppression of apoptosis by estrogen and consequently to endometrial carcinogenesis and prognosis in G1 endometrial cancer.

Tyr phosphatase-mediated P-ERK inhibition suppresses senescence in EIA + v-raf transformed cells, which, paradoxically, are apoptosis-protected in a MEK-dependent manner

Activation of the Ras-Raf-extracellular signal-regulated kinase (ERK) pathway causes not only proliferation and suppression of apoptosis but also the antioncogenic response of senescence. How these contrasting effects are reconciled to achieve cell transformation and cancer formation is poorly understood. In a system of two-step carcinogenesis (dedifferentiated PC EIA, transformed PC EIA-polyoma-middle T [PC EIA + Py] and PC EIA-v-raf [PC EIA + raf] cells], v-raf cooperated with EIA by virtue of a strong prosurvival effect, not elicited by Py-middle T, evident toward serum-deprivation-and H(2)O(2)-induced apoptosis. Apoptosis was detected by DNA fragmentation and annexin V staining. The prosurvival function of v-raf was, in part, mitogen-activated protein kinase/ERK kinase (MEK)-dependent, as shown by pharmacological MEK inhibition. The MEK-dependent antiapoptotic effect of v-raf was exerted despite a lower level of P-ERK1/2 in EIA + raf cells with respect to EIA + Py/EIA cells, which was dependent on a high tyrosine phosphatase activity, as shown by orthovanadate blockade. An ERK1/2 tyrosine phosphatase was likely involved. The high tyrosine phosphatase activity was instrumental to the complete suppression of senescence, detected by β-galactosidase activity, because tyrosine phosphatase blockade induced senescence in EIA + raf but not in EIA + Py cells. High tyrosine phosphatase activity and evasion from senescence were confirmed in an anaplastic thyroid cancer cell line. Therefore, besides EIA, EIA + raf cells suppress senescence through a new mechanism, namely, phosphatase-mediated P-ERK1/2 inhibition, but, paradoxically, retain the oncogenic effects of the Raf-ERK pathway. We propose that the survival effect of Raf is not a function of absolute P-ERK1/2 levels at a given time but is rather dynamically dependent on greater variations after an apoptotic stimulus.

Aberrant methylation of the X-linked ribosomal S6 kinase RPS6KA6 (RSK4) in endometrial cancers

PURPOSE

Effective treatments for advanced endometrial cancer are lacking. Novel therapies that target specific pathways hold promise for better treatment outcomes with less toxicity. Mutation activation of the FGFR2/RAS/ERK pathway is important in endometrial tumorigenesis. RPS6KA6 (RSK4) is a putative tumor suppressor gene and is a target of the ERK signaling pathway. We explored the role of RSK4 in endometrial cancer.

EXPERIMENTAL DESIGN

We showed that RSK4 is expressed in normal endometrial tissue and is absent or much reduced in endometrial cancer. On the basis of previous reports on methylation in other cancers, we hypothesized that the absence of RSK4 transcript is associated with epigenetic silencing rather than mutation. We determined the methylation and expression status of RSK4 in primary endometrial cancers and cell lines and the effects of treatment with a demethylating agent. The relationship between RSK4 methylation and clinicopathologic features was assessed.

RESULTS

RSK4 is frequently hypermethylated in endometrial cancer cells lines and in primary endometrial cancer compared with normal endometrial tissue. RSK4 methylation was significantly associated with tumor grade, with higher grade tumors having lower levels of methylation (P = 0.03). RSK4 methylation levels were not associated with other clinical variables. We did find that RSK4 methylation was significantly correlated with expression in primary endometrial tumors and in cell lines. Reactivation of RSK4 by 5-azacytidine was successfully performed showing 8- to more than 1,200-fold increases in transcript levels.

CONCLUSION

RSK4 appears to be epigenetically silenced in endometrial cancer as evidenced by hypermethylation. Its role as a suppressor in endometrial cancer, however, remains uncertain.

Expression of HER-2 affects patient survival and paclitaxel sensitivity in endometrial cancer

Background:

Disabled phosphatidylinositol 3-kinase (PI3K)/AKT and mitogen-activated protein kinase/extracellular signal-regulated kinase signalling is involved in endometrial carcinogenesis, and there is evidence that expression of epidermal growth factor receptor (EGFR) family members has a role in such intracellular signalling pathways. This study analysed the prognostic impact of EGFR family expression in endometrial cancer in relation to PI3K–AKT and MAPK–ERK signalling, as well as drug sensitivity.

Methods and results:

Immunohistochemical analysis using 63 surgical specimens of endometrioid-type endometrial cancers revealed that EGFR, human epidermal growth factor receptor (HER)-2 and HER-4 were expressed in 25 (39.7%) of 63, 26 (41.3%) of 63 and 31 (49.2%) of 63 tumours, respectively. Gene amplification of HER-2 was observed in 2 of 26 patients with high HER-2 expression. Kaplan–Meier analysis revealed that high HER-2 expression was a factor that negatively influenced the progression-free and overall survival rate (P<0.05), and multivariate analysis showed high HER-2 expression to be an independent prognostic factor. Subsequently, we performed in vitro knockdown analysis to investigate the linkage between HER-2 expression and PI3K–AKT pathways. Short interfering RNA (siRNA)-based knockdown of HER-2 in endometrial cancer cells led to a significant reduction in phosphorylated AKT (p-AKT) expression, indicating the existence of a HER-2/PI3K-AKT axis. As the PI3K–AKT pathway is known to have crucial roles in anticancer drug sensitivity, we examined the involvement of HER-2 in sensitivity to paclitaxel. Short interfering RNA-based knockdown of HER-2 conferred increased sensitivity to paclitaxel in endometrial cancer cells, attenuating the induction of p-AKT on paclitaxel stimulation, which was cancelled by inactivating AKT by the introduction of a dominant-negative form.

Conclusion:

HER-2 is a significant prognostic factor of endometrioid-type endometrial cancer, as well as a key molecule that affects paclitaxel sensitivity by HER-2 interaction with the PI3K–AKT pathway.

Infrequent methylation of the DUSP6 phosphatase in endometrial cancer

OBJECTIVE

Dual-specificity phosphatase six (DUSP6, MKP3, or PYST1) dephosphorylates phosphotyrosine and phosphothreonine residues on ERK-2 (MAPK1) to inactivate the ERK-2 kinase. DUSP6 is a critical regulator of the ERK signaling cascade and has been implicated as a tumor suppressor. DNA methylation in the first intron of DUSP6 abrogates expression in a subset of pancreatic cancers. We sought to determine whether DUSP6 was similarly silenced by methylation in endometrial cancer, a tumor type in which there is frequent activation of the ERK pathway.

METHODS

One hundred and nine endometrial cancers were analyzed for DUSP6 methylation using combined bisulfite restriction analysis (COBRA). The cohort included 70 primary endometrioid endometrial cancers, 21 primary endometrial tumors of adverse histological types, and 18 endometrial cancer cell lines. Primary tumors, cell lines, and normal endometrial tissues were analyzed for DUSP6 mRNA levels using quantitative RT-PCR and pERK levels by Western blots and/or immunohistochemistry.

RESULTS

Methylation of the first intron of the DUSP6 gene was seen in 1/91 primary endometrial cancers investigated. The methylated tumor was also methylated at the more 5' regulatory region of DUSP6. Q-RT-PCR revealed that DUSP6 transcript levels varied widely in primary endometrial tumors. DUSP6 mRNA levels did not correlate with pERK status in primary tumors, consistent with the existence of negative feedback loops activated by pERK that result in transcription of DUSP6.

CONCLUSION

DUSP6 methylation is a rare event in endometrial cancer. Silencing of the DUSP6 phosphatase is unlikely to contribute to constitutive activation of the ERK kinase cascade in endometrial cancer.

MEK inhibition suppresses cell invasion and migration in ovarian cancers with activation of ERK1/2

The extracellular-regulated kinase (ERK) signaling pathway plays an important role in regulating the malignant potential of a cancer cell. However, the effect of ERK signaling on cancer metastasis is not clearly understood. In the present study, we examined the status of ERK activation in 88 ovarian carcinomas in order to clarify the clinicopathological and prognostic significance of phosphorylated ERK1/2 (p-ERK1/2). p-ERK1/2 expression was identified in 37 (42%) of 88 ovarian carcinomas. There was no significant correlation between p-ERK1/2 expression and any of the clinicopathological factors tested. No significant correlation between p-ERK1/2 expression and overall survival was found in patients with ovarian carcinoma treated with platinum and taxane chemotherapy (P=0.426). Next, to clarify the role of ERK1/2 activation in ovarian cancers, we inactivated ERK1/2 in ovarian cancer cells using the MEK inhibitor, CI-1040, which prevents ERK1/2 activation. Based on simulated wound healing and invasion chamber assays, we found that the motility and invasion of ES2 and MPSC1 cells with p-ERK1/2 were significantly reduced (P<0.01) after treatment with CI-1040. By contrast, CI-1040 did not have any effect on KF28 cells, which were negative for p-ERK1/2. Twist was down-regulated simultaneously with p-ERK1/2 following treatment of ES2 and MPSC1 cells with CI-1040. Immunohistochemistry of ovarian carcinoma tissue revealed that the increased expression of p-ERK1/2 significantly correlated with Twist expression (P<0.01). The findings in this study provide new insight into the biological role of ERK signaling in ovarian carcinomas. Additionally, our observations have an important therapeutic implication for patients with ovarian cancers that express p-ERK1/2 as these patients may potentially benefit from CI-1040 therapy.

Genetics of endometrial cancers

Endometrial cancers exhibit a different mechanism of tumorigenesis and progression depending on histopathological and clinical types. The most frequently altered gene in estrogen-dependent endometrioid endometrial carcinoma tumors is PTEN. Microsatellite instability is another important genetic event in this type of tumor. In contrast, p53 mutations or Her2/neu overexpression are more frequent in non-endometrioid tumors. On the other hand, it is possible that the clear cell type may arise from a unique pathway which appears similar to the ovarian clear cell carcinoma. K-ras mutations are detected in approximately 15%–30% of endometrioid carcinomas, are unrelated to the existence of endometrial hyperplasia. A β-catenin mutation was detected in about 20% of endometrioid carcinomas, but is rare in serous carcinoma. Telomere shortening is another important type of genomic instability observed in endometrial cancer. Only non-endometrioid endometrial carcinoma tumors were significantly associated with critical telomere shortening in the adjacent morphologically normal epithelium. Lynch syndrome, which is an autosomal dominantly inherited disorder of cancer susceptibility and is characterized by a MSH2/MSH6 protein complex deficiency, is associated with the development of non-endometrioid carcinomas.

Identification of potential serum markers for endometrial cancer using protein expression profiling

OBJECTIVES

Screening method of endometrial cancer (EC) has not been established yet. Our study was to explore serum biomarkers of EC patients using surface-enhanced laser desorption and ionization-time-of-flight mass spectrometry (SELDI-TOF MS).

METHODS

Serum samples from 65 EC patients and 40 controls were analyzed by SELDI-TOF MS (training set). Single- and multi-variant analyses were performed to compare protein profiles in serum of EC patients and healthy controls. Subsequently, blind test set including 40 EC patients and 40 controls were analyzed for validation.

RESULTS

A panel of four biomarker candidates were selected in training set analysis. These markers could also distinguish stage I patients from controls. Among them, two biomarkers were purified and identified as apolipoprotein A1 and a modified form of apolipoprotein C1. Screening for blind test set using dual-biomarker analysis yielded a sensitivity of 82% and a specificity of 86%.

CONCLUSIONS

Involvement of apolipoproteins with EC is first suggested in this study. In addition to possibility of screening method for EC, findings of these new biomarkers might be related with carcinogenesis or predisposition to EC.

Activated extracellular signal-regulated kinase is an independent prognostic factor in clinically confined renal cell carcinoma

BACKGROUND

Extracellular signal-regulated kinase (ERK) promotes proliferation, metastasis, and poor survival in cancers of the breast, lung, and liver. Advanced localized renal cell carcinoma (RCC) is extraordinarily treatment resistant and has high recurrence rates despite surgery. Limited data exist regarding the prognostic significance of activated (phosphorylated) ERK in RCC. The authors hypothesized that activated ERK (pERK) promotes disease progression and metastasis in localized RCC and may be of value as a biomarker to predict disease recurrence.

METHODS

The expression profile of pERK was examined by immunocytochemistry using a tissue microarray constructed from 174 drug treatment-naive patients who had undergone radical nephrectomy for localized RCC. Levels of tumor-cell specific pERK were scored and correlated with clinicopathologic parameters of RCC and disease-free survival.

RESULTS

Immunostaining for pERK was present in 36% of all RCCs, with a predominance found in the clear cell histologic subtype. High expression was associated with increased tumor size, increased TNM stage, and vascular invasion. Patients with pERK-positive tumors had a mean disease-free survival of 4.19 years, compared with 6.38 years for patients with pERK-negative tumors (P<.001). Cox regression models revealed pERK to be a significant independent predictor of disease-free survival, with a hazards score of 2.9 (P<.001), a value similar to tumor grade (hazards ratio, 3.01; P<.001).

CONCLUSIONS

Expression of pERK is an independent prognostic factor in RCC that is associated with advanced and aggressive pathologic features of renal tumors and predicts the onset of metastasis in patients with localized disease.

Activation of extracellular regulated kinases (ERK1/2) predicts poor prognosis in urothelial bladder carcinoma and is not associated with B-Raf gene mutations

AIM

The analysis of the presence of B-Raf gene mutations in relation to ERK1/2 activation in bladder urothelial carcinoma (UC), in order to determine their potential role in tumour aggressiveness and patients' survival.

METHODS

Polymerase chain reaction-single strand confirmation polymorphism (PCR-SSCP) and sequencing analysis were used for B-Raf gene mutation detection. pERK1/2 and FGFR3 expression were examined by immunohistochemistry in 152 and 116 primary UCs, respectively.

RESULTS

None of the cases displayed mutations in exon 15 of B-Raf gene. Nuclear or cytoplasmic pERK immunoreactivity was displayed in 99.3% and 96.7% of cases, respectively. pERK nuclear expression increased with histological grade and with T-category. Nuclear and cytoplasmic pERK expression was unrelated to FGFR3 expression. In univariate survival analysis of muscle-invasive carcinomas, advanced T-category and higher pERK nuclear expression (p = 0.018) adversely affected survival. However, multivariate analysis in non-invasive as well as in muscle-invasive carcinomas selected only T-category as a significant prognosticator.

CONCLUSIONS

Our findings suggest that elevated pERK expression occurs in UCs in the absence of B-Raf mutations and is not correlated with FGFR3 over-expression. Moreover, it implicates ERK activation in the acquisition of a more aggressive phenotype. However, the assessment of pERK1/2 expression does not seem to add to the prognostic information provided by classical prognosticators.

Episodic Src activation in uveal melanoma revealed by kinase activity profiling

Background:

The RAS/RAF/MEK/ERK pathway is involved in the balance between melanocyte proliferation and differentiation. The same pathway is constitutively activated in cutaneous and uveal melanoma (UM) and related to tumour growth and survival. Whereas mutant BRAF and NRAS are responsible for the activation of the RAS/RAF/MEK/ERK pathway in most cutaneous melanoma, mutations in these genes are usually absent in UM.

Methods:

We set out to explore the RAS/RAF/MEK/ERK pathway and used mitogen-activated protein kinase profiling and tyrosine kinase arrays.

Results:

We identified Src as a kinase that is associated with ERK1/2 activation in UM. However, low Src levels and reduced ERK1/2 activation in metastatic cell lines suggest that proliferation in metastases can become independent of Src and RAS/RAF/MEK/ERK signalling. Inhibition of Src led to the growth reduction of primary UM cultures and cell lines, whereas metastatic cell line growth was only slightly reduced.

Conclusion:

We identified Src as an important kinase and a potential target for treatment in primary UM. Metastasis cell lines seemed largely resistant to Src inhibition and indicate that in metastases treatment, a different approach may be required.

Cell signaling in endometrial carcinoma: phosphorylated 4E-binding protein-1 expression in endometrial cancer correlates with aggressive tumors and prognosis

In the oncogenic process, cell growth control plays a crucial role, and growth factor receptors and their signaling pathways are known to be altered in endometrial cancer, mostly in type I carcinomas. Two main pathways are involved in transmitting the proliferative signal from the membrane receptors to the nucleus: phosphatydil-inositol-3-kinase-protein kinase B-mammalian target of rapamycin and RAS-RAF-ERK pathways. A final effector of these signaling cascades is the cap-dependent mRNA translation initiation complex, which is negatively regulated by 4E-BP1. The aim of our work was to study the relative importance of the factors involved in these pathways and to see their correlation with the clinicopathologic features of the tumors and their prognosis. We studied 120 endometrial carcinomas, including 93 type I and 27 type II carcinomas, and 18 control cases. Tissue microarrays were constructed and immunohistochemistry was performed for HER2, p53, and the phosphorylated forms of protein kinase B, extracellular signal-regulated kinase, and 4E-BP1. HER2 was overexpressed in 11% of carcinomas but not in control cases, and 30% of carcinomas showed activation of protein kinase B and extracellular signal-regulated kinase, mostly in type II carcinomas. The phosphorylated form of 4E-BP1 was found to be cytoplasmic in 31% of cases, and in 63% of cases it showed nuclear expression; the latter was only found in carcinomas. p53 positivity was found in type II and in grade 3 type I carcinomas. This nuclear expression of phospho-4E-BP1 and HER2 overexpression were the only characteristics with prognostic significance. The activation of the signaling pathways that control cell growth is a common event in endometrial carcinomas. 4E-BP1 is a downstream effector of these pathways whose activation status correlates with aggressive phenotypes and prognosis. This factor can reflect the activity of these pathways, regardless of the upstream molecular alterations, and, therefore, it can be a hallmark of the transmission of the oncogenic signal to the nucleus.

KRAS or BRAF mutation status is a useful predictor of sensitivity to MEK inhibition in ovarian cancer

This study examined the status of KRAS and BRAF mutations, in relation to extracellular signal-regulated protein kinase (ERK) activation in 58 ovarian carcinomas to clarify the clinicopathological and prognostic significance of KRAS/BRAF mutations. Somatic mutations of either KRAS or BRAF were identified in 12 (20.6%) out of 58 ovarian carcinomas. The frequency of KRAS/BRAF mutations in conventional serous high-grade carcinomas (4.0% : 1/25) was significantly lower than that in the other histological type (32.3% : 10/31). Phosphorylated ERK1/2 (p-ERK1/2) expression was identified in 18 (38.2%) out of 45 ovarian carcinomas. KRAS/BRAF mutation was significantly correlated with International Federation of Gynecology and Obstetrics (FIGO) stage I, II (P<0.001), and p-ERK1/2 (P<0.001). No significant correlations between KRAS/BRAF mutations or p-ERK1/2 expression and overall survival were found in patients with ovarian carcinoma treated with platinum and taxane chemotherapy (P=0.2460, P=0.9339, respectively). Next, to clarify the roles of ERK1/2 activation in ovarian cancers harbouring KRAS or BRAF mutations, we inactivated ERK1/2 in ovarian cancer cells using CI-1040. Cl-1040 is a compound that selectively inhibits MAP kinase kinase (MEK), an upstream regulator of ERK1/2, and thus prevents ERK1/2 activation. Profound growth inhibition and apoptosis were observed in CI-1040-treated cancer cells with mutations in either KRAS or BRAF in comparison with the ovarian cancer cells containing wild-type sequences. This was evident in both in vitro and in vivo studies. The findings in this study indicate that an activated ERK1/2 pathway is critical to tumour growth and survival of ovarian cancers with KRAS or BRAF mutations. Furthermore, they suggest that the CI-1040-induced phenotypes depend on the mutational status of KRAS and BRAF in ovarian cancers. Therefore, ovarian cancer patients with KRAS or BRAF mutations may benefit from CI-1040 treatment.

Loss of integrin alpha1beta1 ameliorates Kras-induced lung cancer

The collagen IV binding receptor integrin alpha1beta1 has been shown to regulate lung cancer due to its proangiogenic properties; however, it is unclear whether this receptor also plays a direct role in promoting primary lung tumors. To investigate this possibility, integrin alpha1-null mice were crossed with KrasLA2 mice that carry an oncogenic mutation of the Kras gene (G12D) and develop spontaneous primary tumors with features of non-small cell lung cancer. We provide evidence that KrasLA2/alpha1-null mice have a decreased incidence of primary lung tumors and longer survival compared with KrasLA2/alpha1 wild-type controls. Tumors from KrasLA2/alpha1-null mice were also smaller, less vascularized, and exhibited reduced cell proliferation and increased apoptosis, as determined by proliferating cell nuclear antigen and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end staining, respectively. Moreover, tumors from the KrasLA2/alpha1-null mice showed diminished extracellular signal-regulated kinase (ERK) but enhanced p38 mitogen-activated protein kinase activation. Primary lung tumor epithelial cells isolated from KrasLA2/alpha1-null mice showed a significant decrease in anchorage-independent colony formation, collagen-mediated cell proliferation, ERK activation, and, most importantly, tumorigenicity when injected into nude mice compared with KrasLA2/alpha1 wild-type tumor cells. These results indicate that loss of the integrin alpha1 subunit decreases the incidence and growth of lung epithelial tumors initiated by oncogenic Kras, suggesting that both Kras and integrin alpha1beta1 cooperate to drive the growth of non-small cell lung cancer in vivo.

Phospho-ERK staining is a poor indicator of the mutational status of BRAF and NRAS in human melanoma

Mutated BRAF and NRAS are suspected to contribute to melanomagenesis by activation of extracellular signal-regulated kinase (ERK). To test this notion, we analyzed the presence of phosphorylated ERK1/2 in 170 melanomas with established NRAS/BRAF mutational status and well-documented clinical follow-up by immunohistochemistry. Several notable observations were obtained: (i) phospho-ERK staining was very heterogeneous within the tumor; (ii) in most cases, ERK was phosphorylated in only a minority of tumor cells; (iii) the percentage of phospho-ERK-positive cells was not correlated with the mutational status of NRAS and/or BRAF; (iv) the Raf kinase inhibitor protein (RKIP) was expressed homogeneously in virtually all melanoma samples not reflecting the inhomogeneity of phospho-ERK; and, finally, (v) neither the portion of phospho-ERK-positive tumor cells nor the RKIP staining intensity showed any correlation to the clinical course of the patients. Furthermore, the ability of BRAF mutant melanoma cells to downregulate mitogen-activated protein kinase activation was shown in melanoma cell lines cultured at high densities or under nonadherent conditions. Our findings suggest that mitogen-activated protein kinase (MAPK) activity is subject to regulation even in BRAF/NRAS mutant melanoma cells and that high MAPK pathway signaling may be important only in distinct subsets of tumor cells.

Concomitant activation of AKT with extracellular-regulated kinase 1/2 occurs independently of PTEN or PIK3CA mutations in endometrial cancer and may be associated with favorable prognosiss

Deregulated signaling via the phosphatidylinositol 3-kinase (PI3K) pathway is common in many types of cancer, but its clinicopathological significance in endometrial cancer remains unclear. In the present study, we examined the status of the PI3K signaling pathway, especially in relation to PTEN and PIK3CA status, in endometrioid-type endometrial cancer. The immunohistochemical analysis revealed a high level of phosphorylated (p)-AKT expression, which is a hallmark of activated PI3K signaling, in approximately 60% of endometrial cancers. There was no correlation between p-AKT expression and clinicopathological characteristics, such as International Federation of Gynecology and Obstetrics stage, tumor grade, and myometrial invasion. Unexpectedly, a high level of p-AKT expression occurred independently of the presence of PTEN or PIK3CA mutations. Furthermore, p-AKT expression did not correlate with the expression of potential downstream targets, including p-mTOR and p-FOXO1/3a. In turn, p-AKT expression was strongly associated with extracellular-regulated kinase 1/2 expression (P = 0.0031), which is representative of the activated RAS-MAP kinase pathway. Kaplan-Meier analysis suggested that low p-AKT expression was associated with low rates of relapse-free survival, although the difference was not statistically significant, indicating that AKT activation does not confer worse prognosis. The present study demonstrates the presence of complex signaling pathways that might mask the conventional tumorigenic PTEN-PI3K-AKT-mTOR pathway, and strongly suggests a close association between the extracellular-regulated kinase and PI3K pathways in this tumor type.