Breast cancer risk in women treated with augmentation mammoplasty (review).

Surgical implantation of breast prostheses has become increasingly popular while the incidence of breast cancer is increasing each year. There has been no definitive consensus regarding the casual relationship between augmentation mammoplasty and breast cancer incidence, detection, treatment, mortality and survival. This review summarizes the published evidence, including epidemiological studies and case reports. All studies examined state that there is no breast cancer risk in prior augmented women. Moreover, there is also no significant difference in frequency, stage or mean tumor size between augmented and non-augmented women.

Involvement of Akt and mTOR in chemotherapeutic- and hormonal-based drug resistance and response to radiation in breast cancer cells.

Elucidating the response of breast cancer cells to chemotherapeutic and hormonal based drugs and radiation is clearly important as these are common treatment approaches. Signaling cascades often involved in chemo-, hormonal- and radiation resistance are the Ras/PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK and p53 pathways. In the following studies we have examined the effects of activation of the Ras/PI3K/PTEN/Akt/mTOR cascade in the response of MCF-7 breast cancer cells to chemotherapeutic- and hormonal-based drugs and radiation. Activation of Akt by introduction of conditionally-activated Akt-1 gene could result in resistance to chemotherapeutic and hormonal based drugs as well as radiation. We have determined that chemotherapeutic drugs such as doxorubicin or the hormone based drug tamoxifen, both used to treat breast cancer, resulted in the activation of the Raf/MEK/ERK pathway which is often associated with a pro-proliferative, anti-apoptotic response. In drug sensitive MCF-7 cells which have wild-type p53; ERK, p53 and downstream p21 (Cip-1 ) were induced upon exposure to doxorubicin. In contrast, in the drug resistant cells which expressed activated Akt-1, much lower levels of p53 and p21 (Cip1) were induced upon exposure to doxorubicin. These results indicate the involvement of the Ras/PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK and p53 pathways in the response to chemotherapeutic and hormonal based drugs. Understanding how breast cancers respond to chemo- and hormonal-based therapies and radiation may enhance the ability to treat breast cancer more effectively.

Involvement of Akt-1 and mTOR in sensitivity of breast cancer to targeted therapy.

Elucidating the response of breast cancer cells to chemotherapeutic and hormonal based drugs is clearly important as these are frequently used therapeutic approaches. A signaling pathway often involved in chemo- and hormonal-resistance is the Ras/PI3K/PTEN/Akt/mTOR cascades. In the studies presented in this report, we have examined the effects of constitutive activation of Akt on the sensitivity of MCF-7 breast cancer cells to chemotherapeutic- and hormonal-based drugs as well as mTOR inhibitors. MCF-7 cells which expressed a constitutively-activated Akt-1 gene [∆Akt-1(CA)] were more resistant to doxorubicin, etoposide and 4-OH-tamoxifen (4HT) than cells lacking ∆Akt-1(CA). Cells which expressed ∆Akt-1(CA) were hypersensitive to the mTOR inhibitor rapamycin. Furthermore, rapamycin lowered the IC50s for doxorubicin, etoposide and 4HT in the cells which expressed ∆Akt-1(CA), demonstrating a potential improved method for treating certain breast cancers which have deregulated PI3K/PTEN/Akt/mTOR signaling. Understanding how breast cancers respond to chemo- and hormonal-based therapies and the mechanisms by which they can become drug resistant may enhance our ability to treat breast cancer. These results also document the potential importance of knowledge of the mutations present in certain cancers which may permit more effective therapies.

'Genetic profiling' and ovarian cancer therapy (review).

High variability observed among ovarian cancer patients in response to the same therapy and the related toxicity may be correlated to gene polymorphisms and genetic alterations affecting the metabolism of drugs commonly used to treat this tumor. Recent studies have shown a correlation between the polymorphisms characterizing GSTM1-T1 detoxifying enzymes and poor outcome in advanced ovarian cancer patients treated with platinum/paclitaxel-based chemotherapy. Multidrug resistance 1 (mdr-1) polymorphisms were found to be associated with resistance to paclitaxel treatment. Polymorphisms of MRP2, a protein involved in methotrexate, cisplatin and irinotecan active metabolite glucuronide transport, negatively affect platinum-based chemotherapy response. A similar occurrence has been observed with CYP1A1 Ile462Val and ercc1 C118T polymorphisms while patients who were carriers of MTHFR C677T polymorphism had a better response to methotrexate therapy, but an elevated risk of toxicity. Biological therapy with Bevacizumab, the anti-vascular endothelial growth factor has been shown to be less efficient in ovarian cancer patients carrying the polymorphism of the Interleukin-8 gene. Instead, polymorphisms in the XPD gene (Lys751Gln and Asp312Asn), a member of the nucleotide excision repair pathway, positively affects the response to therapy with carboplatin/paclitaxel. Therefore, the study of 'genetic profiling' is crucial to improving the clinician's ability to tailor effective therapy to the molecular profile of the patient while minimizing toxicities. This review describes clinical applications of the above genetic polymorphisms in ovarian cancer patients treated with platinum/paclitaxel-based chemotherapy.

Analysis of matrix metalloproteinase-9 gene polymorphism -1562 C/T in patients suffering from systemic sclerosis with and without ulcers.

The objective of this study was to determine whether the matrix metalloproteinase-9 (MMP-9) rs3918242 single nucleotide polymorphism may confer susceptibility to systemic sclerosis (SSc) with and without ulcers in an Italian Caucasian population. The MMP-9 rs3918242 functional polymorphism was genotyped in 461 subjects of Italian Caucasian origin: 228 patients with SSc (92 with and 136 without ulcers) and 233 unrelated healthy individuals. The SNP under study was in Hardy-Weinberg equilibrium in the control population. Genotype and allele distributions between SSc patients, with or without ulcers, were not statistically significant (p>0.05). A significant increase of the genotype C/T was observed in male SSc patients without ulcers when compared to patients with ulcers (P=0.04). The MMP-9 rs3918242 functional polymorphism is not associated with susceptibility to SSc. However, the presence of the polymorphism may have a protective effect on the development of ulcers in SSc male patients.

Role of genetic polymorphisms and mutations in colorectal cancer therapy (Review).

Gene polymorphisms and mutations in various types of cancer may predict clinical response to chemotherapy and related toxicity, since they may affect the metabolism of the drugs commonly used in combination chemotherapy treatments. However, conflicting data have been generated on this subject. To elucidate this issue, this review discusses the clinical applications of several genetic polymorphisms in colorectal cancer patients treated with the most common agents alone or in combination. UDP-glucuronosyltransferase (UGT)1A1 is a conjugating biotransformation enzyme that plays a role in maintaining the levels of endogenous compounds (e.g., bilirubin) and in handling exogenous compounds, including carcinogens. It has been demonstrated that the UGT1A1*28 polymorphism plays a predictive role in patients administered an irinotecan-containing regimen. Polymorphisms in XPD (Lys751Gln), a member of the nucleotide excision repair pathway, negatively affect response to therapy, with oxaliplatin/5FU reducing the survival of the patient. A similar reaction has also been observed in patients with the XRCC1 Arg399Gln polymorphism, while patients with the GSTP1 Ile105Val polymorphism have an improved response to oxaliplatin/5FU therapy. Treatment with biological compounds such as cetuximab, an anti-epidermal growth factor receptor (EGFR) monoclonal antibody, has been shown to be effective only in colon cancer patients with wild-type K-Ras. Fc polymorphisms are associated with progression-free survival in patients treated with cetuximab. Another monoclonal antibody useful in the treatment of colon cancer is bevacizumab, a monoclonal antibody to vascular endothelial growth factor (VEGF); however, in some cases bevacizumab may cause deep vein thrombosis (DVP). In a related vein, our recent unpublished data show that the VEGF C936T polymorphism may increase the risk of DVP in cancer patients. In conclusion, this review indicates that certain polymorphisms increase the effectiveness of certain drugs, while others greatly enhance their toxicity. The study of the genetic 'habitus' therefore appears to be crucial for the development of tailored therapy for cancer patients.

Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR inhibitors: rationale and importance to inhibiting these pathways in human health.

The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Integral components of these pathways, Ras, B-Raf, PI3K, and PTEN are also activated/inactivated by mutations. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of these pathways can contribute to chemotherapeutic drug resistance, proliferation of cancer initiating cells (CICs) and premature aging. This review will evaluate more recently described potential uses of MEK, PI3K, Akt and mTOR inhibitors in the proliferation of malignant cells, suppression of CICs, cellular senescence and prevention of aging. Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt/mTOR pathways play key roles in the regulation of normal and malignant cell growth. Inhibitors targeting these pathways have many potential uses from suppression of cancer, proliferative diseases as well as aging.

Roles of the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways in controlling growth and sensitivity to therapy-implications for cancer and aging.

Dysregulated signaling through the Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways is often the result of genetic alterations in critical components in these pathways or upstream activators. Unrestricted cellular proliferation and decreased sensitivity to apoptotic-inducing agents are typically associated with activation of these pro-survival pathways. This review discusses the functions these pathways have in normal and neoplastic tissue growth and how they contribute to resistance to apoptotic stimuli. Crosstalk and commonly identified mutations that occur within these pathways that contribute to abnormal activation and cancer growth will also be addressed. Finally the recently described roles of these pathways in cancer stem cells, cellular senescence and aging will be evaluated. Controlling the expression of these pathways could ameliorate human health.

Therapeutic resistance resulting from mutations in Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR signaling pathways.

Chemotherapy remains a commonly used therapeutic approach for many cancers. Indeed chemotherapy is relatively effective for treatment of certain cancers and it may be the only therapy (besides radiotherapy) that is appropriate for certain cancers. However, a common problem with chemotherapy is the development of drug resistance. Many studies on the mechanisms of drug resistance concentrated on the expression of membrane transporters and how they could be aberrantly regulated in drug resistant cells. Attempts were made to isolate specific inhibitors which could be used to treat drug resistant patients. Unfortunately most of these drug transporter inhibitors have not proven effective for therapy. Recently the possibilities of more specific, targeted therapies have sparked the interest of clinical and basic researchers as approaches to kill cancer cells. However, there are also problems associated with these targeted therapies. Two key signaling pathways involved in the regulation of cell growth are the Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways. Dysregulated signaling through these pathways is often the result of genetic alterations in critical components in these pathways as well as mutations in upstream growth factor receptors. Furthermore, these pathways may be activated by chemotherapeutic drugs and ionizing radiation. This review documents how their abnormal expression can contribute to drug resistance as well as resistance to targeted therapy. This review will discuss in detail PTEN regulation as this is a critical tumor suppressor gene frequently dysregulated in human cancer which contributes to therapy resistance. Controlling the expression of these pathways could improve cancer therapy and ameliorate human health.

Understanding rituximab function and resistance: implications for tailored therapy.

The addition of anti-CD20 monoclonal antibody (rituximab) to chemotherapy has significantly improved survival in B-cell lymphoma. However, a substantial number of patients relapse after treatment with rituximab. Understanding of anti-CD20 antibody molecular function may facilitate the development of pharmacologic strategies to overcome resistance. Cell death have been demonstrated to be caused by rituximab binding to CD20 throughout direct and indirect mechanisms. The direct mechanism comprises growth inhibition, induction of apoptosis and sensitization of cells to chemotherapy. While, the indirect mechanisms to Rituximab include complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). However, these mechanisms are still poorly understood. To shed light on this issue, we have analyzed the most significant results showing the role of Rituximab as a signal-inducing antibody and as a chemosensitizing agent through negative regulation of major survival pathways. Mechanisms of resistance to Rituximab are also discussed. Additionally, studies here reported show that, cellular targets are modified after treatment with Rituximab and may become useful for novel therapeutic strategies in the treatment of patients resistant to standard therapy.

Expression and localization of prominin-1 in isoproterenol-treated rat parotid gland.

Prominin-1 (CD133) is a pentaspan cholesterol-binding membrane glycoprotein. Chronic treatment with isoproterenol, a beta-receptor agonist, induces several dramatic effects on salivary glands, such as enhanced DNA synthesis and proliferation of salivary acinar cells. In addition, the biosynthetic pathways of membrane lipids may be altered by the isoproterenol stimulation. The purpose of this study was to investigate the effect of isoproterenol administration on prominin-1 expression profiles in rat parotid gland by means of PCR and immunohistochemistry. Rats were chronically treated with the beta-adrenergic agonist for 1, 3, and 7 days. Our results showed that isoproterenol-treatment caused a down-regulation of prominin-1 on day 3 and 7 of treatment, as well as a differential immunostaining distribution pattern. This study suggests that isoproterenol-treatment may represent a useful tool to explore the molecular mechanisms involved in the synthesis and release of prominin-1. Such efforts could contribute to the development of diagnostic tools based on the detection of prominin-1 in biological fluids, such as saliva.

Abrogation of p53 function leads to metastatic transcriptome networks that typify tumor progression in human breast cancer xenografts.

Development of chromosomal instability (CIN) and consequent phenotypic heterogeneity represent common events during breast cancer progression. Breast carcinomas harboring extensive chromosomal aberrations display a more aggressive behavior characterized by chemoresistance and the propensity to give rise to distant metastases. The tumor suppressor p53 plays a key role in the maintenance of chromosomal stability and tissue homeostasis through activation of cell cycle checkpoints following DNA damage and control of centrosome duplication that ensures equal chromosome segregation during cell division. Furthermore, p53 suppresses CD44 expression and the acquisition of stem cell-like properties responsible for epithelial to mesenchymal transition (EMT) and metastasis. In this study we employed MCF-7 breast cancer cells with endogenous wild-type p53, an engineered MCF-7 variant (vMCF-7(DNP53)) overexpressing a dominant negative p53val135 mutant, and cells re-cultured from vMCF-7(DNP53) tumor xenografts. We carried out an integrative transcriptome and cytogenetic analysis to characterize the mechanistic linkage between loss of p53 function, EMT and consequent establishment of invasive gene signatures during breast cancer progression. We demonstrate that abrogation of p53 function drives the early transcriptome changes responsible for cell proliferation, EMT and survival, while further transcriptome changes that occur during in vivo tumor progression are mechanistically linked to the development of CIN leading to a more invasive and metastatic breast cancer phenotype. Here we identified distinct novel non-canonical transcriptome networks involved in cell proliferation, EMT, chemoresistance and invasion that arise following abrogation of p53 function in vitro and development of CIN in vivo. These studies also have important translational implications since some of the nodal genes identified here are 'druggable' making them appropriate molecular targets for the treatment of breast carcinomas displaying mutant p53, EMT, CIN and high metastatic potential.

Co-regulated expression of matrix metalloproteinase-2 and transforming growth factor-beta in melanoma development and progression.

Previous studies have found that matrix metalloproteinase-2 (MMP-2) and transforming growth factor-beta (TGF-beta) can be considered as biomarkers and indices of disease progression in several human cancers. In this study, we investigated the plasma levels of MMP-2 and TGF-beta and their correlation in 49 primary cutaneous melanoma and 10 metastatic melanoma. Plasma MMP-2 and TGF-beta levels in patients with primary melanoma were significantly higher than those of healthy controls. These protein levels were significantly higher in patients with metastatic melanoma. A positive correlation between plasma levels of MMP-2 and TGF-beta in melanoma patients supports the hypothesis that TGF-beta triggers the release of MMP-2. The immunohistochemistry analysis shows that MMP-2 and TGF-beta were highly expressed in tumor tissues as well as in matched plasma samples. This finding suggests that these proteins are released from tumor cells. Overall, our data indicate that MMP-2 and TGF-beta may represent novel diagnostic markers and therapeutic targets in melanoma and the determination of their concentration could be a useful diagnostic and prognostic indicator. TGF-beta, leading the tissue invasion mediated by MMP-2, is a strong promoter of tumor progression. Therefore, reducing or blocking the activity of TGF-beta may represent a promising target in therapeutic strategies for limiting the growth of melanoma.

Enhancing therapeutic efficacy by targeting non-oncogene addicted cells with combinations of signal transduction inhibitors and chemotherapy.

The effects of inhibition of the Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways and chemotherapeutic drugs on cell cycle progression and drug sensitivity were examined in cytokine-dependent FL5.12 hematopoietic cells. We examined their effects, as these cells resemble normal hematopoietic precursor cells as they do not exhibit "oncogene-addicted" growth, while they do display "cytokine-addicted" proliferation as cytokine removal resulted in apoptosis in greater than 80% of the cells within 48 hrs. When cytokine-dependent FL5.12 cells were cultured in the presence of IL-3, which stimulated multiple proliferation and anti-apoptotic cascades, MEK, PI3K and mTOR inhibitors transiently suppressed but did not totally inhibit cell cycle progression or induce apoptosis while chemotherapeutic drugs such as doxorubicin and paclitaxel were more effective in inducing cell cycle arrest and apoptosis. Doxorubicin induced a G(1) block, while paclitaxel triggered a G(2)/M block. Doxorubicin was more effective in inducing cell death than paclitaxel. Furthermore the effects of doxorubicin could be enhanced by addition of MEK, PI3K or mTOR inhibitors. Cytokine-dependent cells which proliferate in vitro and are not "oncogene-addicted" may represent a pre-malignant stage, more refractory to treatment with targeted therapy. However, these cells are sensitive to chemotherapeutic drugs. It is important to develop methods to inhibit the growth of such cytokine-dependent cells as they may resemble the leukemia stem cell and other cancer initiating cells. These results demonstrate the enhanced effectiveness of targeting early hematopoietic progenitor cells with combinations of chemotherapeutic drugs and signal transduction inhibitors.

The Raf/MEK/ERK pathway can govern drug resistance, apoptosis and sensitivity to targeted therapy.

The effects of the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR signaling pathways on proliferation, drug resistance, prevention of apoptosis and sensitivity to signal transduction inhibitors were examined in FL/DeltaAkt-1:ER*(Myr(+)) + DeltaRaf-1:AR cells which are conditionally-transformed to grow in response to Raf and Akt activation. Drug resistant cells were isolated from FL/DeltaAkt-1:ER*(Myr(+)) + DeltaRaf-1:AR cells in the presence of doxorubicin. Activation of Raf-1, in the drug resistant FL/DeltaAkt-1:ER*(Myr(+)) + DeltaRaf-1:AR cells, increased the IC(50) for doxorubicin 80-fold, whereas activation of Akt-1, by itself, had no effect on the doxorubicin IC50. However, Akt-1 activation enhanced cell proliferation and clonogenicity in the presence of chemotherapeutic drugs. Thus the Raf/MEK/ERK pathway had profound effects on the sensitivity to chemotherapeutic drugs, and Akt-1 activation was required for the long term growth of these cells as well as resistance to chemotherapeutic drugs. The effects of doxorubicin on the induction of apoptosis in the drug resistant cells were enhanced by addition of either mTOR and MEK inhibitors. These results indicate that targeting the Raf/MEK/ERK and PI3K/Akt/mTOR pathways may be an effective approach for therapeutic intervention in drug resistant cancers that have mutations activating these cascades.

Extrahepatic disorders of HCV infection: a distinct entity of B-cell neoplasia?

Some infectious agents have been associated with B-cell lymphoma development. In the last decades, it has been demonstrated that patients infected by hepatitis C virus (HCV) are more likely to develop B-cell non-Hodgkin's lymphoma (NHL) than those uninfected. The prevalence of HCV-infection among NHL patients is reported in this review of all Italian studies on NHL and HCV infection, both case-control and case series. From 18 studies, the prevalence of anti-HCV antibodies in 2736 NHL patients was 19.7% (range: 8.3-37.1%). The association of HCV-infection with each NHL histotype in case-control studies is discussed. Molecular mechanisms by which HCV infection promotes B-cell NHL development is also explored and indicate that HCV-associated lymphomas may be a distinct entity. Clarification of these mechanisms may improve diagnosis, classification and therapy of this subset of NHL. Finally, treatment of HCV-positive patients with lymphoproliferative disorders are herein summarized and further support the notion that HCV infection contributes to the development of these pathologic conditions.

Dominant roles of the Raf/MEK/ERK pathway in cell cycle progression, prevention of apoptosis and sensitivity to chemotherapeutic drugs.

The effects of the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR signaling pathways on cell cycle progression, gene expression, prevention of apoptosis and sensitivity to chemotherapeutic drugs were examined in FL/ΔAkt-1:ER*(Myr(+)) + ΔRaf-1:AR cells which are conditionally-transformed to grow in response to Raf-1 and Akt-1 activation by treatment with testosterone or tamoxifen respectively. In these cells we can compare the effects of normal cytokine vs. oncogene mediated signaling in the same cells by changing the culture conditions. Raf-1 was more effective than Akt-1 in inducing cell cycle progression and preventing apoptosis in the presence and absence of chemotherapeutic drugs. The normal cytokine for these cells, interleukin-3 induced/activated most downstream genes transiently, with the exception of p70S6K that was induced for prolonged periods of time. In contrast, most of the downstream genes induced by either the activate Raf-1 or Akt-1 oncogenes were induced for prolonged periods of time, documenting the differences between cytokine and oncogene mediated gene induction which has important therapeutic consequences. The FL/ΔAkt-1:ER*(Myr(+)) + ΔRaf-1:AR cells were sensitive to MEK and PI3K/mTOR inhibitors. Combining MEK and PI3K/mTOR inhibitors increased the induction of apoptosis. The effects of doxorubicin on the induction of apoptosis could be enhanced with MEK, PI3K and mTOR inhibitors. Targeting the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways may be an effective approach for therapeutic intervention in those cancers which have upstream mutations which result in activation of these pathways.

Dehydroxymethylepoxyquinomicin, a novel nuclear factor-kappaB inhibitor, prevents inflammatory injury induced by interferon-gamma and histamine in NCTC 2544 keratinocytes.

1. The novel nuclear factor (NF)-kappaB inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) is a derivative of the antibiotic epoxyquinomicin C from Amycolatopsis sp. that has been found to inhibit tumour necrosis factor (TNF)-alpha-induced activation of NF-kappaB by suppressing nuclear translocation of NF-kappaB. The aim of the present study was to determine the effects of DHMEQ on interferon (IFN)-gamma- and histamine-activated NCTC 2544 keratinocytes. 2. Keratinocytes were stimulated or not with 200 U/mL IFN-gamma and 10(-4) mol/L histamine in the absence or presence of different concentrations of DHMEQ (1, 5 and 10 microg/mL) or hydrocortisone (10(-5) mol/L), which was used as a reference anti-inflammatory drug. After 48 h, each sample was tested for the presence of intercellular adhesion molecule (ICAM)-1 by western blot analysis, as well as for the release of monocyte chemoattractant protein (MCP)-1, RANTES and interleukin (IL)-8 using specific sandwich ELISAs. To verify the effect of DHMEQ on cell viability of non-stimulated NCTC 2544 keratinocytes, the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used. 3. The results showed that 10 microg/mL DHMEQ potently inhibited ICAM-1 production (by 50%), as well as the release of MCP-1 (to 25% of control), RANTES (to 5% of control) and IL-8 (to 2% of control). The results of the MTT assay indicated that DHMEQ has no effect on cell viability. 4. In conclusion, DHMEQ inhibits the IFN-gamma- and histamine-induced activation of the keratinocyte cell line NCTC 2544. The anti-inflammatory effects of DHMEQ could be exploited by applying the drug topically alone or in combination with sub-toxic concentrations of anti-inflammatory drugs to producer a synergistic effect.

Emerging MEK inhibitors.

IMPORTANCE OF THE FIELD: The Ras/Raf/MEK/ERK pathway is often activated by genetic alterations in upstream signaling molecules. Integral components of this pathway such as Ras and B-Raf are also activated by mutation. The Ras/Raf/MEK/ERK pathway has profound effects on proliferative, apoptotic and differentiation pathways. This pathway can often be effectively silenced by MEK inhibitors. AREAS COVERED BY THIS REVIEW: This review will discuss targeting of MEK which could lead to novel methods to control abnormal proliferation which arises in cancer and other proliferative diseases. This review will cover the scientific literature from 1980 to present and is a follow on from a review which focused on Emerging Raf Inhibitors published in this same review series. WHAT THE READER WILL GAIN: By reading this review the reader will understand the important roles that genetics play in the response of patients to MEK inhibitors, the potential of combining MEK inhibitors with other types of therapy, the prevention of cellular aging and the development of cancer stem cells. TAKE HOME MESSAGE: Targeting MEK has been shown to be effective in suppressing many important pathways involved in cell growth and the prevention of apoptosis. MEK inhibitors have many potential therapeutic uses in the suppression of cancer, proliferative diseases and aging.

Role of hypoxia and autophagy in MDA-MB-231 invasiveness.

Survival strategies adopted by tumor cells in response to a hypoxic stress include activation of hypoxia-inducible factor 1 (HIF-1) and autophagy. However, the importance and the function of each molecular response is not well defined. In the present study, we investigated invasiveness, migration, matrix metalloproteinases (MMPs) activity, and cell survival of MDA-MB-231 cells under normoxia, hypoxia, and hypoxia/reoxygenation (H/R). Moreover, to assess the importance of hypoxia and autophagy on the parameters studied, cells were either left untreated or treated with Chetomin (a selective inhibitor of HIF-1alpha) or trifluoperazine (TFP, an activator of autophagy). We found that hypoxia and H/R stimulated invasiveness and migration of MDA-MB-231 cells with an increased MMP-2 activity. Chetomin and TFP differently regulated the cellular behavior under the oxygenation conditions studied. In fact, Chetomin was most effective in inhibiting cell invasion, MMPs activity, and cell survival under hypoxia but not normoxia or H/R. By contrast, TFP inhibition of cell invasion, migration, and cell survival was independent from oxygenation conditions. TFP-induced autophagy was inhibited by light chain protein 3 (LC3) silencing or 3-methyladenine (3MA) treatment. In fact, LC3-silenced cells were able to invade in the presence of TFP without any GATE16 processing and p62 degradation. Immunofluorescence assay showed that LC3 silencing inhibited TFP-induced autophagosome formation. However, we also showed that both TPF treatment and LC3 silencing caused cytoskeleton impairments suggesting a possible interaction between LC3 and cytoskeleton components. In conclusion, our study shows that hypoxia and autophagy by acting on common (HIF-1alpha) or separate (MMPs, cytoskeleton) targets differently regulate cell invasion, MMPs activity, and survival.