c-myc Promoter-binding protein 1 (MBP-1) regulates prostate cancer cell growth by inhibiting MAPK pathway

Non-metabolic role of alpha-enolase in virus replication

Viruses are extremely complex and highly evolving microorganisms; thus, it is difficult to analyse them in detail. The virion is believed to contain all the essential components required from its entry to the establishment of a successful infection in a susceptible host cell. Hence, the virion composition is the principal source for its transmissibility and immunogenicity. A virus is completely dependent on a host cell for its replication and progeny production. Occasionally, they recruit and package host proteins into mature virion. These incorporated host proteins are believed to play crucial roles in the subsequent infection, although the significance and the molecular mechanism regulated are poorly understood. One such host protein which is hijacked by several viruses is the glycolytic enzyme, Enolase (Eno-1) and is also packaged into mature virion of several viruses. This enzyme exhibits a highly flexible nature of functions, ranging from metabolic to several non-metabolic activities. All the glycolytic enzymes are known to be moonlighting proteins including enolase. The non-metabolic functions of this moonlighting protein are also highly diverse with respect to its cellular localization. Although very little is known about the virological significance of this enzyme, several of its non-metabolic functions have been observed to influence the virus replication cycle in infected cells. In this review, we have attempted to provide a comprehensive picture of the non-metabolic role of Eno-1, its significance in the virus replication cycle and to stimulate interest around its scope as a therapeutic target for treating viral pathologies.

Regulation of Mitogen-Activated Protein Kinase Signaling Pathways by the Ubiquitin-Proteasome System and Its Pharmacological Potential

Mitogen-activated protein kinase (MAPK) cascades are evolutionarily conserved signaling pathways that play essential roles in transducing extracellular environmental signals into diverse cellular responses to maintain homeostasis. These pathways are classically organized into an architecture of three sequentially acting protein kinases: a MAPK kinase kinase that phosphorylates and activates a MAPK kinase, which in turn phosphorylates and activates the effector MAPK. The activity of MAPKs is tightly regulated by phosphorylation of their activation loop, which can be modulated by positive and negative feedback mechanisms to control the amplitude and duration of the signal. The signaling outcomes of MAPK pathways are further regulated by interactions of MAPKs with scaffolding and regulatory proteins. Accumulating evidence indicates that, in addition to these mechanisms, MAPK signaling is commonly regulated by ubiquitin-proteasome system (UPS)-mediated control of the stability and abundance of MAPK pathway components. Notably, the biologic activity of some MAPKs appears to be regulated mainly at the level of protein turnover. Recent studies have started to explore the potential of targeted protein degradation as a powerful strategy to investigate the biologic functions of individual MAPK pathway components and as a new therapeutic approach to overcome resistance to current small-molecule kinase inhibitors. Here, we comprehensively review the mechanisms, physiologic importance, and pharmacological potential of UPS-mediated protein degradation in the control of MAPK signaling. SIGNIFICANCE STATEMENT: Accumulating evidence highlights the importance of targeted protein degradation by the ubiquitin-proteasome system in regulating and fine-tuning the signaling output of mitogen-activated protein kinase (MAPK) pathways. Manipulating protein levels of MAPK cascade components may provide a novel approach for the development of selective pharmacological tools and therapeutics.

Enolase 1, a Moonlighting Protein, as a Potential Target for Cancer Treatment

Enolase 1 (ENO1) is a moonlighting protein, function as a glycolysis enzyme, a plasminogen receptor and a DNA binding protein. ENO1 play an important role in the process of cancer development. The transcription, translation, post-translational modifying activities and the immunoregulatory role of ENO1 at the cancer development is receiving increasing attention. Some function model studies have shown that ENO1 is a potential target for cancer treatment. In this review, we provide a comprehensive overview of the characterization, function, related transduction cascades of ENO1 and its roles in the pathophysiology of cancers, which is a consequence of ENO1 signaling dysregulation. And the development of novels anticancer agents that targets ENO1 may provide a more attractive option for the treatment of cancers. The data of sarcoma and functional cancer models indicates that ENO1 may become a new potential target for anticancer therapy.

Nuclear Enolase-1/ MBP-1 expression and its association with the Wnt signaling in epithelial ovarian cancer

BACKGROUND

Enolase-1, primarily known for its role in glucose metabolism, is overexpressed in various cancer entities. In contrast its alternative spliced nuclear isoform MBP-1 acts as a tumor suppressor. The aim of this study is to analyze the prognostic impact of Enolase-1/ MBP-1 and its functional significance in epithelial ovarian cancer (EOC).

METHODS

By immunohistochemistry, Enolase-1 staining was examined in 156 EOC samples. Evaluation of Enolase-1 staining was conducted in the nucleus and the cytoplasm using the semi-quantitative immunoreactive score. Expression levels were correlated with clinical and pathological parameters as well as with overall survival to assess for prognostic impact.

RESULTS

Cytoplasmic and nuclear Enolase-1 expression did not show a significant difference between the histological subtypes (p = 0.1). High nuclear Enolase-1/ MBP-1 staining negativly correlated with the tumor grading (p<0.001; Cc= -0.318). Cytoplasmic Enolase-1 did not correlate with clinicopathological data. Higher nuclear Enolase-1/ MBP-1 staining was detected in low-grade serous cancer cases compared to high-grade ones (median IRS 3 (range 0-8) vs. median IRS 2 (range 0-4), p<0.001). Nuclear Enolase-1/ MBP-1 expression correlated with the Wnt signaling markers membranous beta-catenin (p = 0.007; Cc=0.235), serine residue 9-phosphorylated glycogen synthase kinase 3 beta (p<0.001; Cc=0.341) and snail/slug (p = 0.004; Cc= -0.257). High nuclear Enolase-1/ MBP-1 expression was associated with improved overall survival (88.6 vs. 33.1 months, median; p = 0.013).

CONCLUSION

Additional knowledge of Enolase-1/ MBP-1 as a biomarker and its interactions within the Wnt signaling pathway and epithelial-mesenchymal transition potentially improve the prognosis of therapeutic approaches in EOC.

Targeting MEK5 impairs nonhomologous end-joining repair and sensitizes prostate cancer to DNA damaging agents

Radiotherapy is commonly used to treat a variety of solid human tumors, including localized prostate cancer. However, treatment failure often ensues due to tumor intrinsic or acquired radioresistance. Here we find that the MEK5/ERK5 signaling pathway is associated with resistance to genotoxic stress in aggressive prostate cancer cells. MEK5 knockdown by RNA interference sensitizes prostate cancer cells to ionizing radiation (IR) and etoposide treatment, as assessed by clonogenic survival and short-term proliferation assays. Mechanistically, MEK5 downregulation impairs phosphorylation of the catalytic subunit of DNA-PK at serine 2056 in response to IR or etoposide treatment. Although MEK5 knockdown does not influence the initial appearance of radiation- and etoposide-induced γH2AX and 53BP1 foci, it markedly delays their resolution, indicating a DNA repair defect. A cell-based assay shows that non-homologous end joining (NHEJ) is compromised in cells with ablated MEK5 protein expression. Finally, MEK5 silencing combined with focal irradiation causes strong inhibition of tumor growth in mouse xenografts, compared with MEK5 depletion or radiation alone. These findings reveal a convergence between MEK5 signaling and DNA repair by NHEJ in conferring resistance to genotoxic stress in advanced prostate cancer and suggest targeting MEK5 as an effective therapeutic intervention in the management of this disease.

Biochanin A protects against PM2.5-induced acute pulmonary cell injury by interacting with the target protein MEK5

Epidemiological studies have shown that exposure to ambient fine particulate matter (PM_2.5) is associated with an increased risk for cardiopulmonary diseases. The MEK5/ERK5 and NF-κB signaling pathways are closely related to the regulation of acute pulmonary cell injury (APCI) and may play an important role in the underlying pathophysiological mechanisms. Related studies have shown that Biochanin A (BCA) effectively interferes with APCI, but the underlying mechanism through which this occurs is not fully understood. Previously, based on proteomic and bioinformatic research, we found the indispensable role of MEK5 in mediating remission effects of BCA against PM_2.5-induced lung toxicity. Therefore, using A549 adenocarcinoma human alveolar basal epithelial cells (A549 cells), we combined western blot and qRT-PCR to study the protective signaling pathways induced by BCA, indicating that MEK5/ERK5 and NF-κB are both involved in mediating APCI in response to PM_2.5, and MEK5/ERK5 positively activated NF-κB and its downstream cellular regulatory factors. BCA significantly suppressed PM_2.5-induced upregulation of MEK5/ERK5 expression and phosphorylation and activation of NF-κB. Furthermore, due to the specificity of the MEK5/ERK5 protein structure, the binding sites and binding patterns of BCA and MEK5 were analyzed using molecular docking correlation techniques, which showed that there are stable hydrogen bonds between BCA and the PB1 domain of MEK5 as well as its kinase domain. BCA forms a stable complex with MEK5, which has potential effects on MEKK2/3-MEK5-ERK5 ternary interactions, p62/αPKC-mediated NF-κB regulation, and inhibition of MEK5 target protein phosphorylation. Therefore, our study suggests that MEK5 is an important regulator of intracellular signaling of APCI in response to PM_2.5 exposure. BCA may exert anti-APCI activity by targeting MEK5 to inhibit activation of the MEK5/ERK5/NF-κB signaling pathway.

Expression of Alpha-Enolase (ENO1), Myc Promoter-Binding Protein-1 (MBP-1) and Matrix Metalloproteinases (MMP-2 and MMP-9) Reflect the Nature and Aggressiveness of Breast Tumors

Breast cancer is a complex and heterogeneous disease: Several molecular alterations cause cell proliferation and the acquisition of an invasive phenotype. Extracellular matrix (ECM) is considered essential for sustaining tumor growth and matrix metalloproteinases (MMPs) have been identified as drivers of many aspects of the tumor phenotype. Mounting evidence indicates that both α-enolase (ENO1) and Myc promoter-binding protein-1 (MBP-1) also played pivotal roles in tumorigenesis, although as antagonists. ENO1 is involved in cell growth, hypoxia tolerance and autoimmune activities besides its major role in the glycolysis pathway. On the contrary, MBP-1, an alternative product of ENO1, suppresses cell proliferation and the invasive ability of cancer cells. Since an important task in personalized medicine is to discriminate a different subtype of patients with different clinical outcomes including chances of recurrence and metastasis, we investigated the functional relationship between ENO1/MBP-1 expression and MMP-2 and MMP-9 activity levels in both tissues and sera of breast cancer patients. We focused on the clinical relevance of ENO1 and MMPs (MMP-2 and MMP-9) overexpression in breast cancer tissues: The association between the higher ENO1, MMP-2 and MMP-9 expression with a worse prognosis suggest that the elevated ENO1 and MMPs expression are promising biomarkers for breast cancer. A relationship seems to exist between MBP-1 expression and the decrease in the activity levels of MMP-9 in cancer tissues and MMP-2 in sera. Moreover, the sera of breast cancer patients grouped for MBP-1 expression differentially induced, in vitro, cell proliferation and migration. Our findings support the hypothesis of patient’s stratification based on ENO1, MBP-1 and MMPs expression. Elucidating the molecular pathways through which MBP-1 influences MMPs expression and breast cancer regression can lead to the discovery of new management strategies.

When Place Matters: Shuttling of Enolase-1 Across Cellular Compartments

Enolase is a glycolytic enzyme, which catalyzes the inter-conversion of 2-phosphoglycerate to phosphoenolpyruvate. Altered expression of this enzyme is frequently observed in cancer and accounts for the Warburg effect, an adaptive response of tumor cells to hypoxia. In addition to its catalytic function, ENO-1 exhibits other activities, which strongly depend on its cellular and extracellular localization. For example, the association of ENO-1 with mitochondria membrane was found to be important for the stability of the mitochondrial membrane, and ENO-1 sequestration on the cell surface was crucial for plasmin-mediated pericellular proteolysis. The latter activity of ENO-1 enables many pathogens but also immune and cancer cells to invade the tissue, leading further to infection, inflammation or metastasis formation. The ability of ENO-1 to conduct so many diverse processes is reflected by its contribution to a high number of pathologies, including type 2 diabetes, cardiovascular hypertrophy, fungal and bacterial infections, cancer, systemic lupus erythematosus, hepatic fibrosis, Alzheimer's disease, rheumatoid arthritis, and systemic sclerosis. These unexpected non-catalytic functions of ENO-1 and their contributions to diseases are the subjects of this review.

The Biological Significance and Regulatory Mechanism of c-Myc Binding Protein 1 (MBP-1)

Alternatively translated from the ENO gene and expressed in an array of vertebrate and plant tissues, c-Myc binding protein 1 (MBP-1) participates in the regulation of growth in organisms, their development and their environmental responses. As a transcriptional repressor of multiple proto-oncogenes, vertebrate MBP-1 interacts with other cellular factors to attenuate the proliferation and metastasis of lung, breast, esophageal, gastric, bone, prostrate, colorectal, and cervical cancer cells. Due to its tumor-suppressive property, MBP-1 and its downstream targets have been investigated as potential prognostic markers and therapeutic targets for various cancers. In plants, MBP-1 plays an integral role in regulating growth and development, fertility and abiotic stress responses. A better understanding of the functions and regulatory factors of MBP-1 in plants may advance current efforts to maximize plant resistance against drought, high salinity, low temperature, and oxidative stress, thus optimizing land use and crop yields. In this review article, we summarize the research advances in biological functions and mechanistic pathways underlying MBP-1, describe our current knowledge of the ENO product and propose future research directions on vertebrate health as well as plant growth, development and abiotic stress responses.

The genomic features of parasitism, Polyembryony and immune evasion in the endoparasitic wasp Macrocentrus cingulum

BACKGROUND

Parasitoid wasps are well-known natural enemies of major agricultural pests and arthropod borne diseases. The parasitoid wasp Macrocentrus cingulum (Hymenoptera: Braconidae) has been widely used to control the notorious insect pests Ostrinia furnacalis (Asian Corn Borer) and O. nubilalis (European corn borer). One striking phenomenon exhibited by M. cingulum is polyembryony, the formation of multiple genetically identical offspring from a single zygote. Moreover, M. cingulum employs a passive parasitic strategy by preventing the host's immune system from recognizing the embryo as a foreign body. Thus, the embryos evade the host's immune system and are not encapsulated by host hemocytes. Unfortunately, the mechanism of both polyembryony and immune evasion remains largely unknown.

RESULTS

We report the genome of the parasitoid wasp M. cingulum. Comparative genomics analysis of M. cingulum and other 11 insects were conducted, finding some gene families with apparent expansion or contraction which might be linked to the parasitic behaviors or polyembryony of M. cingulum. Moreover, we present the evidence that the microRNA miR-14b regulates the polyembryonic development of M. cingulum by targeting the c-Myc Promoter-binding Protein 1 (MBP-1), histone-lysine N-methyltransferase 2E (KMT2E) and segmentation protein Runt. In addition, Hemomucin, an O-glycosylated transmembrane protein, protects the endoparasitoid wasp larvae from being encapsulated by host hemocytes. Motif and domain analysis showed that only the hemomucin in two endoparasitoids, M. cingulum and Venturia canescens, possessing the ability of passive immune evasion has intact mucin domain and similar O-glycosylation patterns, indicating that the hemomucin is a key factor modulating the immune evasion.

CONCLUSIONS

The microRNA miR-14b participates in the regulation of polyembryonic development, and the O-glycosylation of the mucin domain in the hemomucin confers the passive immune evasion in this wasp. These key findings provide new insights into the polyembryony and immune evasion.

Hepatitis C virus-induced CCL5 secretion from macrophages activates hepatic stellate cells

Hepatitis C virus (HCV)-mediated chronic liver disease is a serious health problem around the world and often causes fibrosis/cirrhosis and hepatocellular carcinoma. The mechanism of liver disease progression during HCV infection is still unclear, although inflammation is believed to be an important player in disease pathogenesis. We previously reported that macrophages including Kupffer cells exposed to HCV induce proinflammatory cytokines. These secreted cytokines may activate hepatic stellate cells (HSCs) toward fibrosis. In this study, we examined crosstalk between macrophages and HSCs following HCV infection. Primary human HSCs and immortalized HSCs (LX2 cells) were incubated with conditioned medium derived from HCV-exposed human macrophages. Expression of inflammasome and fibrosis-related genes in these cells was examined, with increased expression of inflammatory (NLR family pyrin domain containing 3, interleukins 1β and 6, and cysteine-cysteine chemokine ligand 5 [CCL5]) and profibrogenic (transforming growth factor β1, collagen type 4 alpha 1, matrix metalloproteinase 2, and alpha-smooth muscle actin) markers. Further investigation suggested that CCL5, secreted from HCV-exposed macrophages, activates inflammasome and fibrosis markers in HSCs and that neutralizing antibody to CCL5 inhibited activation.

CONCLUSION

Together, our results demonstrate that human macrophages exposed to HCV induce CCL5 secretion, which plays a significant role in hepatic inflammation and fibrosis. (Hepatology 2017;66:746-757).

MEK5 overexpression is associated with the occurrence and development of colorectal cancer

BACKGROUND

Mitogen/extracellular signal-regulated kinase kinase-5 (MEK5) has been confirmed to play a pivotal role in tumor carcinogenesis and progression. However, few studies have investigated the role of MEK5 in colorectal cancer (CRC).

METHODS

MEK5 expression was determined by immunohistochemistry (IHC) in tissue microarrays (TMAs) containing 2 groups of tissues, and western blotting was used to confirm MEK5 expression in 8 cases of primary CRC tissues and paired normal mucosa. RNA interference was used to verify the biological function of MEK5 gene in the development of CRC.

RESULTS

IHC revealed the expression of MEK5 was higher in tumor tissues (38.1 %), compared with adjacent normal tissue (8.3 %). Western blot showed that, MEK5 expression was upregulated in CRC tumor tissues compared with normal tissue. Analysis of clinical pathology parameters indicated MEK5 overexpression was significantly correlated with the depth of invasion, lymph node metastasis, distant metastasis and histological grade. Survival analysis revealed that MEK5 overexpression negatively correlated with cancer-free survival (hazard ratio 1.64, P = 0.017). RNA interference-mediated knockdown of MEK5 in SW480 colon cancer cells decreased their proliferation, division, migration and invasiveness in vitro and slowed down tumors growth in mice engrafted with the cells.

CONCLUSION

MEK5 plays an important role in CRC progression and may be a potential molecular target for the treatment of CRC.

[α-Enolase (ENO1) inhibits epithelial-mesenchymal transition in the A549 cell line by suppressing ERK1/2 phosphorylation]

背景与目的

已有的研究表明：上皮间质转换（epithelial-mesenchymal transition, EMT）是非小细胞肺癌发展和转移的一个重要过程，受到众多信号通路的精细调节。经典的丝裂原活化激酶（mitogen activated protein kinase, MAPK）信号通路是转化生长因子（transforming growth factor β, TGFβ）诱导EMT发生的必要条件。本研究以非小细胞肺癌细胞系A549为模型，对烯醇化酶（enolase-1, ENO1）影响细胞EMT过程的分子机制进行了初步研究。

方法

建立稳定过表达ENO1的A549细胞，用划痕实验检测细胞运动能力；用Western blot技术检测EMT过程相关分子标志物的变化；通过TGFβ-1诱导实验检测ENO1过表达对EMT的影响；通过上皮生长因子（epidermal growth factor, EGF）诱导实验和Western blot检测ENO1过表达引起胞外信号调节激酶（extracellular signal regulated protein kinase, ERK）磷酸化的改变。

结果

ENO1过表达抑制A549细胞侧向迁移能力。ENO1过表达还会引起上皮样标志物E-cadherin表达上调，同时间质样标志物N-cadherin和Vimentin表达下降；TGFβ-1诱导实验也证实了ENO1对EMT进程的抑制作用。EGF活化实验显示ENO1对ERK磷酸化的抑制作用。

结论

在非小细胞肺癌细胞中，ENO1具有抑制细胞EMT的作用，且很可能是通过抑制MAPK通路来实现。

Proteomic analysis of differentially expressed proteins in 5-fluorouracil-treated human breast cancer MCF-7 cells

BACKGROUND

5-Fluorouracil (5-Fu) is a commonly used chemotherapeutic agent in clinical care of breast cancer patients. However, the mechanism of how the 5-Fu works is complex and still largely unknown.

OBJECTIVE

The objective of this study was to understand the mechanism further and explore the new targets of 5-Fu.

METHODS

The differentially expressed proteins induced by 5-Fu in human breast cancer MCF-7 cells were identified by proteomic analysis. Four differentially expressed proteins were validated using Western blot and quantitative real-time reverse-transcription polymerase chain reaction analysis for protein and mRNA levels. The effect of 5-Fu on MCF-7 cells was determined by cell viability assay, transmission electron microscopy and flow cytometry analysis.

RESULTS

5-Fu dose-dependently inhibited cell proliferation with the IC50 value of 98.2 μM. 5-Fu also induced obviously morphological change and apoptosis in MCF-7 cells. Twelve differentially expressed proteins involved in energy metabolism, cytoskeleton, cellular signal transduction and tumor invasion and metastasis were identified.

CONCLUSION

These results may provide a new insight into the molecular mechanism of 5-Fu in therapy of breast cancer.

miR-888 is an expressed prostatic secretions-derived microRNA that promotes prostate cell growth and migration

MicroRNAs (MiRNAs) are a growing class of small non-coding RNAs that exhibit widespread dysregulation in prostate cancer. We profiled miRNA expression in syngeneic human prostate cancer cell lines that differed in their metastatic potential in order to determine their role in aggressive prostate cancer. miR-888 was the most differentially expressed miRNA observed in human metastatic PC3-ML cells relative to non-invasive PC3-N cells, and its levels were higher in primary prostate tumors from cancer patients, particularly those with seminal vesicle invasion. We also examined a novel miRNA-based biomarker source called expressed prostatic secretions in urine (EPS urine) for miR-888 expression and found that its levels were preferentially elevated in prostate cancer patients with high-grade disease. These expression studies indicated a correlation for miR-888 in disease progression. We next tested how miR-888 regulated cancer-related pathways in vitro using human prostate cancer cell lines. Overexpression of miR-888 increased proliferation and migration, and conversely inhibition of miR-888 activity blocked these processes. miR-888 also increased colony formation in PC3-N and LNCaP cells, supporting an oncogenic role for this miRNA in the prostate. Our data indicates that miR-888 functions to promote prostate cancer progression and can suppress protein levels of the tumor suppressor genes RBL1 and SMAD4. This miRNA holds promise as a diagnostic tool using an innovative prostatic fluid source as well as a therapeutic target for aggressive prostate cancer.

Role of p90(RSK) in regulating the Crabtree effect: implications for cancer

High glucose inhibits mitochondrial respiration, known as the 'Crabtree effect', in cancer cells and possibly other cell types. The upstream pathways regulating this phenomenon are poorly understood. In diabetes, where glucose levels are elevated, the p90(RSK) (p90 ribosomal S6 kinase) has received much attention as a potential upstream mediator of the effects of high glucose. Evidence is also emerging that p90(RSK) may play a role in cancer cell signalling, although the role of p90(RSK) in regulating cancer cell metabolism is unclear. In the present paper, we provide an overview of the Crabtree effect and its relationship to mitochondrial metabolism. Furthermore, preliminary data are presented suggesting a role for p90(RSK) and its upstream components, the ERK (extracellular-signal-regulated kinase) family of MAPKs (mitogen-activated protein kinases), in the Crabtree effect.

Expression of the phosphorylated MEK5 protein is associated with TNM staging of colorectal cancer

BACKGROUND

Activation of MEK5 in many cancers is associated with carcinogenesis through aberrant cell proliferation. In this study, we determined the level of phosphorylated MEK5 (pMEK5) expression in human colorectal cancer (CRC) tissues and correlated it with clinicopathologic data.

METHODS

pMEK5 expression was examined by immunohistochemistry in a tissue microarray (TMA) containing 335 clinicopathologic characterized CRC cases and 80 cases of nontumor colorectal tissues. pMEK5 expression of 19 cases of primary CRC lesions and paired with normal mucosa was examined by Western blotting. The relationship between pMEK5 expression in CRC and clinicopathologic parameters, and the association of pMEK5 expression with CRC survival were analyzed respectively.

RESULTS

pMEK5 expression was significantly higher in CRC tissues (185 out of 335, 55.2%) than in normal tissues (6 out of 80, 7.5%; P < 0.001). Western blotting demonstrated that pMEK5 expression was upregulated in 12 of 19 CRC tissues (62.1%) compared to the corresponding adjacent nontumor colorectal tissues. Overexpression of pMEK5 in CRC tissues was significantly correlated to the depth of invasion (P = 0.001), lymph node metastasis (P < 0.001), distant metastasis (P < 0.001) and high preoperative CEA level (P < 0.001). Consistently, the pMEK5 level in CRC tissues was increased following stage progression of the disease (P < 0.001). Analysis of the survival curves showed a significantly worse 5-year disease-free (P = 0.002) and 5-year overall survival rate (P < 0.001) for patients whose tumors overexpressed pMEK5. However, in multivariate analysis, pMEK5 was not an independent prognostic factor for CRC (DFS: P = 0.139; OS: P = 0.071).

CONCLUSIONS

pMEK5 expression is correlated with the staging of CRC and its expression might be helpful to the TNM staging system of CRC.

Bitter melon extract impairs prostate cancer cell-cycle progression and delays prostatic intraepithelial neoplasia in TRAMP model

Prostate cancer remains the second leading cause of cancer deaths among American men. Earlier diagnosis increases survival rate in patients. However, treatments for advanced disease are limited to hormone ablation techniques and palliative care. Thus, new methods of treatment and prevention are necessary for inhibiting disease progression to a hormone refractory state. One of the approaches to control prostate cancer is prevention through diet, which inhibits one or more neoplastic events and reduces the cancer risk. For centuries, Ayurveda has recommended the use of bitter melon (Momordica charantia) as a functional food to prevent and treat human health related issues. In this study, we have initially used human prostate cancer cells, PC3 and LNCaP, as an in vitro model to assess the efficacy of bitter melon extract (BME) as an anticancer agent. We observed that prostate cancer cells treated with BME accumulate during the S phase of the cell cycle and modulate cyclin D1, cyclin E, and p21 expression. Treatment of prostate cancer cells with BME enhanced Bax expression and induced PARP cleavage. Oral gavage of BME, as a dietary compound, delayed the progression to high-grade prostatic intraepithelial neoplasia in TRAMP (transgenic adenocarcinoma of mouse prostate) mice (31%). Prostate tissue from BME-fed mice displayed approximately 51% reduction of proliferating cell nuclear antigen expression. Together, our results suggest for the first time that oral administration of BME inhibits prostate cancer progression in TRAMP mice by interfering cell-cycle progression and proliferation.

Mitogen/extracellular signal-regulated kinase kinase-5 promoter region polymorphisms affect the risk of sporadic colorectal cancer in a southern Chinese population

Mitogen/extracellular signal-regulated kinase kinase-5 (MEK5), which belongs to a network of mitogen-activated protein kinase pathways, play a pivotal role in carcinogenesis. The purpose of this study was to investigate whether variants in the MEK5 gene promoter were involved in susceptivity of individuals to sporadic colorectal cancer (CRC). In the present hospital-based case-control study of 737 patients with sporadic CRC and 703 healthy control subjects in a southern Chinese population, the two polymorphisms of MEK5 promoter (i.e., rs7172582C>T and rs3743354T>C) were genotyped by TaqMan assay. There were significant differences between cases and controls in the genotype and allele distribution of the MEK5 gene rs3743354T>C polymorphism. The rs3743354 CC genotype was associated with a significantly decreased risk of CRC when compared with the TT genotype (adjusted odds ratios [ORs]=0.43; 95% confidence interval [CI], 0.24-0.77). Compared to the T allele, a significant correlation was detected between the presence of the C allele and decreased risk of CRC (adjusted OR=0.79; 95% CI, 0.61-0.94). The decreased risk of CRC associated with rs3743354 variant genotypes (i.e., CT+CC) was found in the smoker subgroup (adjusted OR=0.63; 95% CI=0.45-0.88). Further, environmental factors, including smoking and drinking, interacted with rs3743354C variant genotypes to reduce CRC risk. Western blot analysis showed that the levels of MEK5 protein in sporadic CRC neoplastic tissues and adjacent normal colorectal epithelium tissues were lower in the carriers of rs3743354 CC genotypes than that in those with rs3743354 TT genotypes or those with rs3743354 TC genotypes. However, no significant association was found between the rs7172582C>T polymorphism and risk of CRC. These data indicate that the rs3743354 polymorphism in the MEK5 promoter may affect the risk of developing CRC.

RN181 suppresses hepatocellular carcinoma growth by inhibition of the ERK/MAPK pathway

The activation of oncogenes and the inactivation of tumor suppressor genes by mutations or chronic hepatitis virus infections play key roles in the pathogenesis of hepatocellular carcinoma (HCC). Here we report that RN181, a really interesting new gene finger domain-containing protein, was down-regulated in highly malignant cell lines and in tumor cells of 139 HCC clinical samples in comparison with adjacent normal liver tissues. The expression of RN181 was strongly associated with the pathological grade of HCC. Alterations of the expression of RN181 by retrovirus-transduced up-regulation and short hairpin RNA-mediated down-regulation demonstrated the function of RN181 as a tumor suppressor because it decreased the proliferation and colony formation of HCC cells in vitro and inhibited tumor growth in vivo by suppressing cell proliferation and enhancing cell apoptosis in xenografted tumors. Proteomic analyses showed that RN181 regulates the expression of many proteins that are important in many cellular processes. Statistical analyses identified 33 proteins with consistent changes (≥2-fold) in RN181-transformed cells. Ten of these proteins were up-regulated by RN181, and 23 were down-regulated. Representative proteins were validated by western blotting. Interaction network investigations revealed that 20 RN181-regulated proteins could integrate several key biological processes such as survival, metabolism, and mitogen-activated protein kinase (MAPK) pathways. Remarkably, 11 of the 33 proteins are associated with MAPK signaling in one or more ways. RN181 suppressed the tyrosine phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in cell lines and in tumor cells of xenografts and HCC clinical samples, and removing the suppression increased tumor growth.

CONCLUSION

We have shown that RN181 suppresses the tumorigenesis of HCC through the inhibition of ERK/MAPK signaling in the liver. Our results provide new insights into the pathogenesis of HCC and may help with the development of novel therapeutic strategies.

2-D gel electrophoresis-based proteomic analysis reveals that ormeloxifen induces G0-G1 growth arrest and ERK-mediated apoptosis in chronic myeloid leukemia cells K562

Ormeloxifen is a nonsteroidal selective estrogen receptor modulator (SERM) and has been shown to possess anticancer activities in breast and uterine cancer. Here, we show that ormeloxifen induces apoptosis in dose-dependent manner in a variety of leukemia cells, more strikingly in K562. 2-DE-gel electrophoresis of K562 cells induced with ormeloxifen showed that 57 and 30% of proteins belong to apoptosis and cell-cycle pathways, respectively. Our data demonstrate that ormeloxifen-induced apoptosis in K562 cells involves activation of extracellular signal-regulated kinases (ERKs) and subsequent cytochrome c release, leading to mitochondria-mediated caspase-3 activation. Ormeloxifen-induced apoptosis via ERK activation was drastically inhibited by prior treatment of K562 cells with ERK inhibitor PD98059. Ormeloxifen also inhibits proliferation of K562 cells by blocking them in G0-G1 phase by inhibiting c-myc promoter via ormeloxifen-induced MBP-1 (c-myc promoter-binding protein) and upregulation of p21 expression. We further show that ormeloxifen-induced apoptosis in K562 is translatable to mononuclear cells isolated from chronic myeloid leukemia (CML) patients. Thus, ormeloxifen induces apoptosis in K562 cells via phosphorylation of ERK and arrests them in G0-G1 phase by reciprocal regulation of p21 and c-myc. Therefore, inclusion of ormeloxifen in the therapy of chronic myeloid leukemia can be of potential utility.

Myc promoter-binding protein-1 (MBP-1) is a novel potential prognostic marker in invasive ductal breast carcinoma

BACKGROUND

Alpha-enolase is a glycolytic enzyme that catalyses the formation of phosphoenolpyruvate in the cell cytoplasm. α-Enolase and the predominantly nuclear Myc promoter-binding protein-1 (MBP-1) originate from a single gene through the alternative use of translational starting sites. MBP-1 binds to the P2 c-myc promoter and competes with TATA-box binding protein (TBP) to suppress gene transcription. Although several studies have shown an antiproliferative effect of MBP-1 overexpression on several human cancer cells, to date detailed observations of α-enolase and MBP-1 relative expression in primary tumors versus normal tissues and their correlation with clinicopathological features have not been undertaken.

METHODOLOGY AND FINDINGS

We analyzed α-enolase and MBP-1 expression in normal breast epithelium and primary invasive ductal breast carcinoma (IDC) from 177 patients by Western blot and immunohistochemical analyses, using highly specific anti-α-enolase monoclonal antibodies. A significant increase in the expression of cytoplasmic α-enolase was observed in 98% of the tumors analysed, compared to normal tissues. Nuclear MBP-1 was found in almost all the normal tissues while its expression was retained in only 35% of the tumors. Statistically significant associations were observed among the nuclear expression of MBP-1 and ErbB2 status, Ki-67 expression, node status and tumor grade. Furthermore MBP-1 expression was associated with good survival of patients with IDC.

CONCLUSIONS

MBP-1 functions in repressing c-myc gene expression and the results presented indicate that the loss of nuclear MBP-1 expression in a large number of IDC may be a critical step in the development and progression of breast cancer and a predictor of adverse outcome. Nuclear MBP-1 appears to be a novel and valuable histochemical marker with potential prognostic value in breast cancer.

MBP-1 is efficiently encoded by an alternative transcript of the ENO1 gene but post-translationally regulated by proteasome-dependent protein turnover

The c-myc promoter-binding protein-1 (MBP-1) is a transcriptional suppressor of tumorigenesis and thought to be the product of alternative translation initiation of the α-enolase (ENO1) transcript. In the present study, we cloned a 2552-bp novel cDNA with a putative coding sequence of MBP-1 and functionally examined its ability to encode the MBP-1 protein. Similarly to ENO1, the obtained MBP-1 was widely and differentially expressed in a variety of normal tissues and cancer cells. Experiments using MBP-1 promoter-driven luciferase reporter assays, biochemical cell fractionation followed by RT-PCR detection of the cytoplasmic mRNA, and transcription/translation-coupled reactions, consistently demonstrated that this novel transcript was alternatively transcribed from intron III of the ENO1 gene and was feasible for MBP-1 production. Hypoxia treatments significantly increased the transcriptional activation of the MBP-1 gene. Blocking the proteasomal degradation by MG132 stabilized the MBP-1 protein in cells. Compared with the translation efficiency for production of the MBP-1 protein, the MBP-1 transcript was 17.8 times more efficient than the ENO1 transcript. Thus, we suggest that this newly discovered transcript is a genuine template for the protein synthesis of MBP-1 in cells, and optimal expression of this gene in tumors may lead to effective clinical therapies for cancers.

MBP-1 suppresses growth and metastasis of gastric cancer cells through COX-2

The c-Myc promoter binding protein 1 (MBP-1) is a transcriptional suppressor of c-myc expression and involved in control of tumorigenesis. Gastric cancer is one of the most frequent neoplasms and lethal malignancies worldwide. So far, the regulatory mechanism of its aggressiveness has not been clearly characterized. Here we studied roles of MBP-1 in gastric cancer progression. We found that cell proliferation was inhibited by MBP-1 overexpression in human stomach adenocarcinoma SC-M1 cells. Colony formation, migration, and invasion abilities of SC-M1 cells were suppressed by MBP-1 overexpression but promoted by MBP-1 knockdown. Furthermore, the xenografted tumor growth of SC-M1 cells was suppressed by MBP-1 overexpression. Metastasis in lungs of mice was inhibited by MBP-1 after tail vein injection with SC-M1 cells. MBP-1 also suppressed epithelial-mesenchymal transition in SC-M1 cells. Additionally, MBP-1 bound on cyclooxygenase 2 (COX-2) promoter and downregulated COX-2 expression. The MBP-1-suppressed tumor progression in SC-M1 cells were through inhibition of COX-2 expression. MBP-1 also exerted a suppressive effect on tumor progression of other gastric cancer cells such as AGS and NUGC-3 cells. Taken together, these results suggest that MBP-1-suppressed COX-2 expression plays an important role in the inhibition of growth and progression of gastric cancer.

Quantitative proteomic profiling of prostate cancer reveals a role for miR-128 in prostate cancer

Multiple, complex molecular events characterize cancer development and progression. Deciphering the molecular networks that distinguish organ-confined disease from metastatic disease may lead to the identification of biomarkers of cancer invasion and disease aggressiveness. Although alterations in gene expression have been extensively quantified during neoplastic progression, complementary analyses of proteomic changes have been limited. Here we interrogate the proteomic alterations in a cohort of 15 prostate-derived tissues that included five each from adjacent benign prostate, clinically localized prostate cancer, and metastatic disease from distant sites. The experimental strategy couples isobaric tags for relative and absolute quantitation with multidimensional liquid phase peptide fractionation followed by tandem mass spectrometry. Over 1000 proteins were quantified across the specimens and delineated into clinically localized and metastatic prostate cancer-specific signatures. Included in these class-specific profiles were both proteins that were known to be dysregulated during prostate cancer progression and new ones defined by this study. Enrichment analysis of the prostate cancer-specific proteomic signature, to gain insight into the functional consequences of these alterations, revealed involvement of miR-128-a/b regulation during prostate cancer progression. This finding was validated using real time PCR analysis for microRNA transcript levels in an independent set of 15 clinical specimens. miR-128 levels were elevated in benign prostate epithelial cell lines compared with invasive prostate cancer cells. Knockdown of miR-128 induced invasion in benign prostate epithelial cells, whereas its overexpression attenuated invasion in prostate cancer cells. Taken together, our profiles of the proteomic alterations of prostate cancer progression revealed miR-128 as a potentially important negative regulator of prostate cancer cell invasion.

Generally detected proteins in comparative proteomics--a matter of cellular stress response?

The specificity of proteins identified by proteomics as biomarkers for defined conditions or as components of biological processes and pathways is crucial. We critically reviewed differentially expressed proteins from comparative proteomic studies identified by 2-DE followed by MS, especially with MALDI technique. Based on 66 of those studies, a list of 44 proteins is presented as generally detected proteins regardless of species, in vivo or in vitro conditions, tissues and organs, and experimental objective. Similarly, a list of 28 generally detected protein families is presented. The enriched functions linked to these generally detected proteins reveal that there are some common biological features beyond the technical limitations. Cellular stress response can be the universal reason as to why these proteins are generally expressed differentially. Using those proteins as biomarkers for cellular processes other than stress response should be done with caution. In future proteomic studies more profound approaches should be applied to look beyond these proteins to find specific biomarkers. Our results are discussed in relation to a recent viewpoint publication by Petrak et al. [Proteomics 2008, 8, 1744-1749].

Comparative proteomics and molecular mechanical analysis in CDA-II induced therapy of LCI-D20 hepatocellular carcinoma model

PURPOSE

To investigate the differential proteins and related molecular mechanism of CDA-II (cell differentiation agent-II) induced therapy on a human hepatocellular carcinoma model in nude mice with high metastatic potential (LCI-D20).

METHODS

After tumors were transplanted 11 days, mice were intraperitoneally injected with CDA-II (1,800 mg/kg) for 20 days continuously. The tumor growth-inhibitory efficiency in CDA-II treated groups was calculated. Proteins extracted from tumor tissue were separated by two-dimensional gel electrophoresis (2DE) and the differential proteins were identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). Western blotting (WB) was performed to verify the expression of certain candidate proteins. Reverse transcription-polymerase chain reaction (RT-PCR) was engaged to study the molecular mechanism of the therapy.

RESULTS

CDA-II suppressed the growth and metastasis of tumor. The tumor growth-inhibitory efficiency was 41.8%. In total, 27 differentially expressed proteins were identified, including HSP27, UGDH, CK8, Hsp60, ENOA and AnxA5, with functions involved in oncogene expression and/or cell differentiation. In addition, apparent alternations of HSP60 and beta-actin expression levels and their different posttranslational modifications (PTMs) were investigated. RT-PCR analysis confirmed that the cancer related genes c-myc, N-ras and MMP-9 were significantly down-regulated.

CONCLUSION

Our results demonstrate that CDA-II presence can change the proteome profiling and favors of the tumor suppression in LCI-D20 cell differentiation. Our results also suggest that the dynamic PTM of HSP60 expression levels could be used to predict HCC and might be a promising and useful biomarker to prognosticate CDA-II therapeutic efficacy.

The activated Notch1 receptor cooperates with alpha-enolase and MBP-1 in modulating c-myc activity

The Notch signal pathway plays multifaceted roles to promote or suppress tumorigenesis. The Notch1 receptor intracellular domain (N1IC), the activated form of the Notch1 receptor, activates the c-myc proto-oncogene. The complex of N1IC and transcription factor YY1 binds to the human c-myc promoter to enhance c-myc expression in a CBF1-independent manner. Here we demonstrated that N1IC interacted with the c-Myc-regulating proteins alpha-enolase and c-myc promoter binding protein 1 (MBP-1). Both alpha-enolase and MBP-1 suppressed the N1IC-enhanced activity of the c-myc promoter in a CBF1-independent manner. The YY1 response element in front of the P2 c-myc promoter was essential and sufficient for the modulation of c-myc by N1IC and alpha-enolase or MBP-1. Furthermore, N1IC, YY1, and alpha-enolase or MBP-1 but not CBF1 bound to the c-myc promoter through associating with the YY1 response element. Hemin-induced erythroid differentiation was suppressed by N1IC in K562 cells. This suppression was relieved by the expression of alpha-enolase and MBP-1. In addition, both alpha-enolase and MBP-1 suppressed the N1IC-enhanced colony-forming ability through c-myc. These results indicate that the activated Notch1 receptor and alpha-enolase or MBP-1 cooperate in controlling c-myc expression through binding the YY1 response element of the c-myc promoter to regulate tumorigenesis.

Proteomic characterization of angiogenic endothelial cells stimulated with cancer cell-conditioned medium

To characterize the protein expression profiles and identify the molecules associated with tumor angiogenesis, the cellular proteins of human umbilical vein endothelial cells (HUVECs) in response to cancer cell-conditioned medium (CM) prepared from HT1080 human fibrosarcoma cells were analyzed using fluorescence-labeled 2D gel-based proteomics. Most differentially expressed proteins in HT1080-CM-stimulated cells were found to be downregulated (88%) rather than upregulated (12%) based on statistical analysis of protein spot signals. Additionally, we examined the effects of vascular endothelial cell growth factor (VEGF), a proangiogenic factor, on cellular protein expression. In contrast, most differentially expressed proteins were found to be upregulated (59%) rather than downregulated (41%) in VEGF-stimulated HUVECs. Comparative analyses of 29 and 35 protein species identified in CM-stimulated and VEGF-stimulated HUVECs, respectively, revealed the remarkable differences between these two stimulations. Only four proteins were differentially expressed by both treatments: annexin A2, enolase 1, and T-plastin (downregulated by CM but upregulated by VEGF), and RAN (downregulated by both CM and VEGF). These findings provide new information regarding the regulation of protein expression associated with tumor angiogenesis.

Comparative proteomic analysis of chronic myelogenous leukemia cells: inside the mechanism of imatinib resistance

Imatinib is the first molecular targeted therapy that has shown clinical success, but imatinib acquired resistance, although a rare event, is critical during the therapy of chronic myelogenous leukaemia (CML). With the aim of better understanding the molecular mechanisms accompanying acquisition of resistance to this drug, a comparative proteomic approach was undertaken on CML cell lines LAMA 84 S (imatinib sensitive) and LAMA 84 R (imatinib resistant). Forty-four differentially expressed proteins were identified and categorized into five main functional classes: (I) heat shock proteins and chaperones; (II) nucleic acid interacting proteins (binding/synthesis/stability); (III) structural proteins, (IV) cell signaling, and (V) metabolic enzymes. Several heat shock proteins known to complex Bcr-Abl were overexpressed in imatinib resistant cells, showing a possible involvement of these proteins in the mechanism of resistance. HnRNPs also resulted in being up-regulated in imatinib resistant cells. These proteins have been shown to be strongly and directly related to Bcr-Abl activity. To our knowledge, this is the first direct proteomic comparison of imatinib sensitive/resistant CML cell lines.

Forkhead protein FKHR and its phosphorylated form p-FKHR in human prostate cancer

In vitro studies suggest that the proapoptotic function of forkhead protein FKHR is probably inactivated by means of phosphorylation through the protein kinase B pathway. However, the clinical significance of FKHR in prostate cancer remains unclear. Six hundred forty radical prostatectomies were used for building tissue microarrays. Slides were stained with antibodies against FKHR and phosphorylated FKHR (p-FKHR). Correlations with clinicopathologic parameters were analyzed by Spearman rank test. Cox regression test and Kaplan-Meier test were used to determine the probability of disease recurrence, which is defined as a serum prostate-specific antigen (PSA) level greater than 0.4 ng/mL after radical prostatectomy. Nuclear FKHR level was higher in normal prostate than in benign prostatic hyperplasia and prostate cancer (P = .0000). Nuclear expression of FKHR was correlated with preoperative PSA level (rho = 0.108, P = .029), extracapsular extension (rho = 0.137, P = .005), and seminal vesicle invasion (rho = 0.101, P = .039). FKHR expression was not a significant indicator of biochemical failure by either univariate or multivariate analysis. Nuclear p-FKHR expression correlated with patients' age (rho = 0.179, P = .0003), Gleason score (rho = 0.130, P = .0083), extracapsular extension (rho = 0.227, P = .0000), clinical stage (Union Internationale Contre le Cancer system) (rho = 0.166, P = .0007), and lymph node status (rho = 0.101, P = .0401). Cytoplasmic p-FKHR correlated with patients' age (rho = 0.146, P = .0030) and clinical stage (rho = 0.117, P = .0180). Cytoplasmic p-FKHR was a significant indicator of biochemical recurrence (P = .0164; hazard ratio, 1.114-2.929). Nuclear p-FKHR strongly correlated with phosphorylated protein kinase B (rho = 0.368, P = .0000), androgen receptor (rho = 0.385, P = .0000), and Skp-2 (rho = 0.170, P = .0036). Our data suggest that the proapoptotic role of FKHR is probably regulated by several signaling pathways in prostate cancer.

Proteomic Signatures in Laryngeal Squamous Cell Carcinoma

Laryngeal cancer remains a worldwide health problem. The identification of biomarkers unique to laryngeal cancer may provide new insights into its pathogenesis, as well as provide potential targets for novel therapies and early detection. In order to identify potential biomarkers, we performed a proteomic analysis of laryngeal cancer specimens. Using two-dimensional differential in-gel electrophoresis and mass spectroscopy, protein expression profiles from two laryngeal carcinoma specimens and corresponding adjacent normal tissue were analyzed. The results of our analysis showed that the expression of a number of proteins was significantly altered in the tumor specimens when compared to matched normal controls. The differentially expressed proteins were identified, and they included stratifin, S100 calcium-binding protein A9, p21-ARC, stathmin, and enolase. With these findings, we have identified potential biomarkers which may contribute to the pathogenesis of laryngeal carcinoma, and which may be suitable as targets for novel therapeutic and/or diagnostic modalities.

Knockdown of MBP-1 in human prostate cancer cells delays cell cycle progression

We have previously shown that MBP-1 acts as a general transcriptional repressor, and forced expression of MBP-1 exerts an anti-proliferative effect on a number of human cancer cells. In this report, we have investigated the role of endogenous MBP-1 in cell growth regulation. For this, we generated human prostate cancer cells (PC3) stably transfected with short hairpin RNA targeting MBP-1. We have observed retarded growth and longer doubling time of MBP-1 knockdown PC3 cells as compared with control mock-transfected PC3 cells. Fluorescence-activated cell sorter analysis suggested that PC3 cells expressing MBP-1-specific small interfering RNA accumulated during G2/M phase of the cell cycle. Further analysis suggested that depletion of MBP-1 was associated with reduction of cyclin A and cyclin B1 expression when compared with that of the control cells. A delayed induction of cyclin A and B1 expression was observed in MBP-1-depleted PC3 cells (PC3-4.2) upon serum stimulation, although the level of expression was much lower than that of control PC3 cells. Supplementation of MBP-1 in PC3-4.2 cells restored cyclin A and cyclin B1 expression. Together, these results suggest that knockdown of MBP-1 in prostate cancer cells perturbs cell proliferation by inhibiting cyclin A and cyclin B1 expression.

Endocrine regulation of prostate cancer growth

Prostate cancer is one of the most frequently diagnosed malignant neoplasms in the Western world. The focus of this article is on regulation of proliferation, apoptosis, angiogenesis and differentiation by steroid and peptide hormones. Steroid hormones, in particular androgens and estrogens, exert their effects through respective receptors. The androgen receptor is functional in all stages of the disease and it can be activated in a ligand-dependent and -independent manner. In prostate cancer, expression of some androgen receptor coactivators increases during tumor progression. Interleukins and transforming growth factor-β are multifunctional regulators of prostate growth and proliferation. Signal transduction cascades of fibroblast growth factors and insulin-like growth factors are responsible for increased survival and angiogenesis in prostate cancer. In clinical specimens obtained from prostate cancer, there is an increased phosphorylation of mitogen-activated protein kinase and Akt kinase, whose action in the regulation of cell survival is redundant.