Focal adhesion kinase: a promising target for anticancer therapy

Focal adhesion kinase (FAK) is a protein tyrosine kinase acting as an early modulator of the integrin signalling cascade, thus regulating various basic cellular functions. In transformed cells, upregulation of FAK protein expression and uncontroled signalling were held responsible for the promotion of malignant phenotypic characteristics, as well as resistance to chemotherapy and radiotherapy. Direct FAK targeting resulted in the inhibition of the malignant phenotype of cancer cells, whereas increased apoptotic rates of cancer cells, either used alone or in combination with conventional chemotherapeutic agents, radiotherapy or hormonal therapy. Furthermore, drugs used in cancer chemotherapy, besides their basic mode of action, were also shown to act through altering FAK signalling. Finally, positive results were noted by the transfection of cancer cells with fak mutants or genes that suppress FAK expression or activity, such as phosphatase and tensin homolog deleted on chromosome Ten (PTEN), ribonucleotide reductase M1 polypeptide (RRM1) and melanoma differentiation-associated gene-7 (mda-7). The purpose of this article is a comprehensive review of the existing data on the possible use of FAK targeting in anticancer therapy.     

Phosphorylation of human enhancer of filamentation (HEF1) on serine 369 induces its proteasomal degradation

Human enhancer of filamentation 1 (HEF1) is a multi-domain docking protein of the p130 Cas family. HEF1 is present at focal adhesions and is involved in integrin signalling mediating cytoskeleton reorganization associated with cell migration, adhesion or apoptosis. HEF1 functions are regulated in part by phosphorylation on tyrosine residues. HEF1 is also phosphorylated on serines/threonines leading to two isoforms refered to as p105 and p115. In most cases, the serine/threonine kinase(s) responsible for HEF1 phosphorylation have not been identified. In the present study, we have investigated HEF1 ser/thr phosphorylation. In the HCT-116 cell line transiently overexpressing Flag-HEF1 we showed that Hesperadin, a synthetic indolinone displaying antiproliferative effect and described as an inhibitor of various kinases including Aurora-B, prevented HEF1 phosphorylation induced by the ser/thr phosphatase PP2A inhibitor: okadaic acid (OA). In addition we showed that conversion of endogenous HEF1 p105 to p115 in HaCaT cells was prevented upon treatment with Hesperadin, resulting in accumulation of p105HEF1. We also identified serine 369 as the target site of phosphorylation by this Hesperadin-inhibited kinase in HCT-116. Finally, we provide evidence that phosphorylation on serine 369 but not phosphorylation on serine 296, triggers HEF1 degradation by the proteasomal machinery. These data suggest that conversion of p105 to p115 results from a ser-369-dependent phosphorylation mediated by an Hesperadin-sensitive kinase and regulates the half-life of HEF1.     

A Discovery Strategy for Selective Inhibitors of c‐Src in Complex with the Focal Adhesion Kinase SH3/SH2‐binding Region

The c‐Src tyrosine kinase co‐operates with the focal adhesion kinase to regulate cell adhesion and motility. Focal adhesion kinase engages the regulatory SH3 and SH2 domains of c‐Src, resulting in localized kinase activation that contributes to tumor cell metastasis. Using assay conditions where c‐Src kinase activity required binding to a tyrosine phosphopeptide based on the focal adhesion kinase SH3‐SH2 docking sequence, we screened a kinase‐biased library for selective inhibitors of the Src/focal adhesion kinase peptide complex versus c‐Src alone. This approach identified an aminopyrimidinyl carbamate compound, WH‐4‐124‐2, with nanomolar inhibitory potency and fivefold selectivity for c‐Src when bound to the phospho‐focal adhesion kinase peptide. Molecular docking studies indicate that WH‐4‐124‐2 may preferentially inhibit the ‘DFG‐out’ conformation of the kinase active site. These findings suggest that interaction of c‐Src with focal adhesion kinase induces a unique kinase domain conformation amenable to selective inhibition.     

Direct inhibitory effect of curcumin on Src and focal adhesion kinase activity

Curcumin (diferuloylmethane) is a well-known agent with anti-inflammatory, antioxidant, and anticarcinogenic properties. In this study, we observed that curcumin inhibited the kinase activity of v-Src, which led to a decrease in tyrosyl substrate phosphorylation of Shc, cortactin, and FAK. Our in vitro kinase experiment revealed that the inhibitory effect of curcumin on Src could be direct. Consistent with the abrogation of Src activity was the reduction of Src-Tyr-416 phosphorylation, Src-mediated Shc-Tyr-317 phosphorylation, decreased ERK activation, and cell proliferation in v-Src transformed cells. Remarkably, curcumin not only exerted its negative effect on FAK via the disappearance of Src-mediated FAK phosphorylation, but also directly inhibited its enzymatic activity. Concurrent to reduced cortactin tyrosyl phosphorylation and FAK kinase activity was the abolishment of v-Src-mediated cell mobility. To our knowledge, this is the first report indicating that curcumin can retard cellular growth and migration via downregulation of Src and FAK kinase activity.     

Transinactivation of the epidermal growth factor receptor tyrosine kinase and focal adhesion kinase phosphorylation by dietary flavonoids: effect on invasive potential of human carcinoma cells

Focal adhesion kinase (FAK), a member of a growing family of structurally distinct protein tyrosine kinases (PTK), has been linked to specific phosphorylation events, and the elevation of FAK activity in human carcinoma cells correlated with increased invasive potential. Transactivation of the epidermal growth factor receptor (EGFR) tyrosine kinase activity is proposed to stimulate cell migration and the subsequent activation of downstream signaling pathways. Quercetin (Qu) and luteolin (Lu), are potent PTK inhibitors as well as putative chemopreventive agents. The present work, we demonstrate that Qu and Lu at concentration of 20 microM transinactivated EGFR tyrosine kinase activity with marked reduction in phosphotyrosyl level of 170, 125, 65, 60 and 42 kDa cellular proteins, and induced apoptosis in MiaPaCa-2 cells. The 125 kDa protein was further identified as a FAK by immunoprecipitation and immunoblotting analyses. Tumor cells treated with Lu or Qu dampened the phosphorylation of FAK. In addition, our data clearly demonstrated that tumor cells responded to Qu and Lu by parallel reductions in the levels of phosphorylated FAK and the secreted matrix metalloproteinase (MMP) that may lead to the suppression of invasive potential and cell migration in vitro. While the molecular mechanism of FAK regulation of MMP secretion in tumor cells remains unclear, our results suggested that blockade of the EGFR-signaling pathway may contributed to the net effect. As suggested in the current study, targeting EGFR and FAK with the objective of modulating their regulatory pathways could offer prospects for the treatment of EGFR-responsive cancers in the future.     

Focal adhesion kinase inhibitors in the treatment of metastatic cancer: a patent review

Introduction: Focal adhesion kinase (FAK) plays a prominent role in integrin signaling. FAK activation increases phosphorylation of Tyr397 and other sites of the protein. FAK-dependent activation of signaling pathways implicated in controlling essential cellular functions including growth, proliferation, survival and migration. FERM (F for the 4.1 protein, ezrin, radixin and moesin) domain-enhanced p53 degradation plays a critical role in proliferation and survival. FAK, overexpressed in metastatic tumors, has emerged as an important therapeutic target for the development of selective inhibitors. FAK inhibitors achieved tumor growth inhibition and induced apoptosis. Strategies targeting FAK inhibition using novel compounds have created an exciting opportunity for anticancer therapy.

Areas covered: This review summarizes the current research with available data from early phase clinical trials and discusses the available small-molecule inhibitors of FAK from patents. The importance of inhibiting FAK activity in cancer patients is discussed.

Expert opinion: Emerging data from clinical trials with orally available small-molecule inhibitors of FAK are promising. Although this approach is appropriate as a targeted therapeutic approach against several metastatic cancer types, several compounds in research are yet to prove their preclinical efficacy. This report lays special emphasis on the available patent data of FAK inhibitors for such targeted molecular therapies. This review summarizes current knowledge about FAK inhibition in cancer therapy.     

Tumor angiogenesis--a potential target in cancer chemoprevention.

Tumor angiogenesis is critically important for the growth of solid tumors as tumors remain in dormant phase for a long time in the absence of the initiation of blood vessel formation. Tumors can grow up to approximately 2mm size without requirement of blood supply as diffusion is sufficient at this level to support the removal of wastes from and supply of nutrients to tumor cells. Therefore, angiogenesis process could be an important target to suppress tumor growth and metastasis. Angiogenesis is required at almost every step of tumor progression and metastasis, and tumor vasculature has been identified as strong prognostic marker for tumor grading. Endothelial cells are the main players of angiogenesis process and could be peculiar target for antiangiogenic therapy because they are non-transformed and easily accessible to achievable concentrations of antiangiogenic agents, and also are unlikely to acquire drug resistance. Several antiangiogenic strategies have been developed to inhibit tumor growth by targeting different components of tumor angiogenesis. Chemopreventive agents have been shown to target and inhibit different aspects and components of angiogenesis process and can be used conveniently as they are mostly non-toxic natural compounds and could be part of our daily diet. However, a risk assessment for the use of antiangiogenic phytochemicals is needed as they can also disrupt normal physiologic angiogenesis such as wound healing and endometrium development processes. This review focuses on how different chemopreventive phytochemicals target various components of angiogenesis, including angiogenic signaling, which usually starts from tumor cells producing angiogenic factors and affecting endothelial cells growth, migration and capillary vessel organization for tumor angiogenesis.     

Checks and balances: interplay of RTKs and PTPs in cancer progression

In recent years, targeted therapies for receptor tyrosine kinases (RTKs) have shown initial promise in the clinical setting for the treatment of several tumors driven by these oncogenic signaling pathways. Unfortunately, clinical relapse due to acquired resistance to these molecular therapeutics is common. An improved understanding of how tumors bypass the inhibitory effects of RTK-targeted therapies has revealed a rich myriad of possible mechanisms for acquired resistance. Protein tyrosine phosphatases (PTPs) can function as oncogenes or tumor suppressors to either enhance or suppress RTK signaling. Recent studies suggest that the loss or gain of function of PTP's can significantly impinge on RTK signaling during tumor progression. Here we review the interplay between RTKs and PTPs as an emerging mechanism for acquired resistance to RTK-targeted therapies, that may aid in the design of improved therapies to prevent and overcome resistance in treatments for cancer patients.     

Phosphatase of regenerating liver: a novel target for cancer therapy

Introduction: Phosphatases of regenerating livers (PRLs) are novel oncogenes that interact with many well-established cell signaling pathways that are misregulated in cancer, and are known to drive cancer metastasis when overexpressed.

Areas covered: This review covers basic information of the discovery and characteristics of the PRL family. We also report findings on the role of PRL in cancer, cell functions and cell signaling. Furthermore, PRL's suitability as a novel drug target is discussed along with current methods being developed to facilitate PRL inhibition.

Expert opinion: PRLs show great potential as novel drug targets for anticancer therapeutics. Studies indicate that PRL can perturb major cancer pathways such as Src/ERK1/2 and PTEN/PI3K/Akt. Upregulation of PRLs has also been shown to drive cancer metastasis. However, in order to fully realize its therapeutic potential, a deeper understanding of the function of PRL in normal tissue and in cancer must be obtained. Novel and integrated biochemical, chemical, biological, and genetic approaches will be needed to identify PRL substrate(s) and to provide proof-of-concept data on the druggability of the PRL phosphatases.     

Targeting RET for thyroid cancer therapy

The limited efficacy of conventional treatments in progressive thyroid carcinomas indicates the need for new therapeutic options. Activating mutations of the receptor tyrosine kinase-encoding RET gene have been identified as driving oncogenic events in subsets of papillary (PTC) and medullary (MTC) thyroid carcinomas suggesting the interest of targeted therapy. The role of RET oncogenes and the encoded constitutively active oncoproteins as potential targets has been investigated by different strategies including gene therapy and pharmacological approaches, but targeted treatment for RET-driven cancers is not clinically available in current therapy. Small molecule tyrosine kinase inhibitors, including sorafenib, sunitinib, motesanib and vandetanib, which have already shown efficacy against other neoplastic diseases, are being evaluated in clinical trials for treatment of thyroid carcinomas. Most of them, also described as Ret inhibitors, are multi-kinase inhibitors with antiangiogenic activity related to inhibition of receptor tyrosine kinases, such as the vascular endothelial growth factor receptors. Preclinical evidence supports the relevance of Ret oncoproteins as therapeutic targets for a subset of thyroid neoplastic diseases and, although targeting the original causal genetic change may not be sufficient to control the disease efficiently, the available knowledge outlines therapeutic opportunities for exploiting Ret inhibition.     

Interaction between the insulin receptor and Grb14: a dynamic study in living cells using BRET

Grb14 is a molecular adaptor that binds to the activated insulin receptor (IR) and negatively regulates insulin signaling. We have studied the dynamics of interaction of the IR with Grb14, in real time, in living HEK cells, using bioluminescence resonance energy transfer (BRET). Insulin rapidly and dose-dependently stimulated this interaction. Removing insulin from the incubation medium only resulted in a modest decrease in BRET signal, indicating that the interaction between the IR and Grb14 can remain long after insulin stimulus has disappeared. BRET saturation experiments indicated that insulin markedly increases the affinity between IR and Grb14, resulting in recruitment of the adaptor to the activated IR. In addition, using both BRET and co-immunoprecipitation experiments, we demonstrated that insulin induced the dimerization of Grb14, most likely as a result of simultaneous binding of two Grb14 molecules on the activated IR. We also investigated the relationships between IR, Grb14 and the protein tyrosine phosphatase PTP1B. We observed that insulin-induced BRET between the IR and PTP1B was markedly reduced by Grb14, suggesting that Grb14 regulated this interaction in living cells. Using site-specific antibodies against phosphorylated tyrosines of the insulin receptor, we showed that Grb14 protected the three tyrosines of the kinase loop from dephosphorylation by PTP1B, while favouring dephosphorylation of tyrosine 972. This resulted in decreased IRS-1 binding to the IR and decreased activation of the ERK pathway. Our work suggests that Grb14 may regulate signalling through the insulin receptor by controlling its tyrosine-dephosphorylation in a site-specific manner.     

Reduction of metastasis, cell invasion, and adhesion in mouse osteosarcoma by YM529/ONO-5920-induced blockade of the Ras/MEK/ERK and Ras/PI3K/Akt pathway

Osteosarcoma is one of the most common primary malignant bone tumors in children and adolescents. Some patients continue to have a poor prognosis, because of the metastatic disease. YM529/ONO-5920 is a nitrogen-containing bisphosphonate that has been used for the treatment of osteoporosis. YM529/ONO-5920 has recently been reported to induce apoptosis in various tumors including osteosarcoma. However, the mode of metastasis suppression in osteosarcoma by YM529/ONO-5920 is unclear. In the present study, we investigated whether YM529/ONO-5920 inhibited tumor cell migration, invasion, adhesion, or metastasis in the LM8 mouse osteosarcoma cell line. We found that YM529/ONO-5920 significantly inhibited metastasis, cell migration, invasion, and adhesion at concentrations that did not have antiproliferative effects on LM8 cells. YM529/ONO-5920 also inhibited the mRNA expression and protein activities of matrix metalloproteinases (MMPs). In addition, YM529/ONO-5920 suppressed phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) and the serine/threonine protein kinase B (Akt) by the inhibition of Ras prenylation. Moreover, U0126, a mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor, and LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, also inhibited LM8 cell migration, invasion, adhesion, and metastasis, as well as the mRNA expression and protein activities of MMP-1, MMP-2, MMP-9, and MT1-MMP. The results indicated that YM529/ONO-5920 suppressed the Ras/MEK/ERK and Ras/PI3K/Akt pathways, thereby inhibiting LM8 cell migration, invasion, adhesion, and metastasis. These findings suggest that YM529/ONO-5920 has potential clinical applications for the treatment of tumor cell metastasis in osteosarcoma.     

Relevance of mitogen activated protein kinase (MAPK) and phosphotidylinositol-3-kinase/protein kinase B (PI3K/PKB) pathways to induction of apoptosis by curcumin in breast cells

Following observations that curcumin inhibited proliferation (IC(50)=1-5 microM), invasiveness and progression through S/G2/M phases of the cell cycle in the non-tumourigenic HBL100 and tumourigenic MDA-MB-468 human breast cell lines, it was noted that apoptosis was much more pronounced in the tumour line. Therefore, the ability of curcumin to modulate signalling pathways which might contribute to cell survival was investigated. After pre-treatment of cells for 20 min, curcumin (40 microM) inhibited EGF-stimulated phosphorylation of the EGFR in MDA-MB-468 cells and phosphorylation of extracellular signal regulated kinases (ERKs) 1 and 2, as well as ERK activity and levels of nuclear c-fos in both cell lines. At a lower dose (10 microM), it also inhibited the ability of anisomycin to activate JNK, resulting in decreased c-jun phosphorylation, although it did not inhibit JNK activity directly. In contrast, the activation of p38 mitogen activated protein kinase (MAPK) by anisomycin was not inhibited. Curcumin inhibited basal phosphorylation of Akt/protein kinase B (PKB) in both cell lines, but more consistently and to a greater extent in the MDA-MB-468 cells. The MAPK kinase (MKK) inhibitor U0126 (10 microM), while preventing ERK phosphorylation in MDA-MB-468 cells, did not induce apoptosis. The PI3K inhibitor LY294002 (50 microM) inhibited PKB phosphorylation in both cells lines, but only induced apoptosis in the MDA-MB-468 line. These results suggest that while curcumin has several different molecular targets within the MAPK and PI3K/PKB signalling pathways that could contribute to inhibition of proliferation and induction of apoptosis, inhibition of basal activity of Akt/PKB, but not ERK, may facilitate apoptosis in the tumour cell line.     

Stimulation of proliferation and migration of a colorectal cancer cell line by amidated and glycine-extended gastrin-releasing peptide via the same receptor

Although amidated forms of gastrin-releasing peptide (GRP) have been identified as autocrine growth factors in small cell lung cancer, their role in the development and progression of colorectal carcinoma is less clear. In addition, the biological activity of non-amidated gastrin-releasing peptide has not been investigated in colorectal carcinoma cells. We therefore investigated the effect of bombesin (a homologue of gastrin-releasing peptide) on proliferation, migration and inositol phosphate production in the human colorectal carcinoma cell line DLD-1, and determined the ability of gastrin-releasing peptide receptor antagonists to inhibit these effects. We also compared the biological activities of amidated and non-amidated GRP in the same assays. Treatment with either bombesin, or amidated or non-amidated GRP resulted in significant increase in proliferation, and in migration in a wound-healing assay. Both the mitogenic and migratory effects of amidated and non-amidated forms were inhibited by the GRP receptor antagonist [d-Phe⁶, Leu-NHet¹³, des-Met¹⁴]-bombesin(6-13). The presence of GRP receptor mRNA and GRP binding sites in three colorectal carcinoma cell lines was demonstrated by RT-PCR and by binding of radiolabelled bombesin, respectively. Transfection of DLD-1 cells with a dominant negative phosphatidylinositol 3-kinase did not affect bombesin-stimulated cell proliferation, but inhibited bombesin-stimulated cell migration. Bombesin and GRPgly activated phospholipase C, mitogen-activated protein kinase and focal adhesion kinase. We conclude that both amidated and non-amidated forms of gastrin-releasing peptide accelerate proliferation and migration of DLD-1 human colorectal carcinoma cells via the gastrin-releasing peptide receptor, but that phosphatidylinositol 3-kinase is only involved in the cell migration signalling pathway. Our results suggest a potential role for gastrin-releasing peptide receptor antagonists in the management of colorectal carcinoma.     

Activation of deoxycytidine kinase by protein kinase inhibitors and okadaic acid in leukemic cells

Deoxycytidine kinase (dCK) is a key enzyme in the deoxynucleoside salvage pathway and in the activation of numerous nucleoside analogues used in cancer and antiviral chemotherapy. Recent studies indicate that dCK activity might be regulated through reversible phosphorylation. Here, we report the effects of a large panel of protein kinase inhibitors on dCK activity in the B-leukemia cell line EHEB, both in basal conditions and in the presence of the nucleoside analogue 2-chloro-2'-deoxyadenosine (CdA) which induces activation of dCK. Except staurosporine and H-7 that significantly reduced the activation of dCK by CdA, no specific protein kinase inhibitor diminished basal dCK activity or its activation by CdA. In contrast, genistein, a general protein tyrosine kinase inhibitor, and AG-490, an inhibitor of JAK2 and JAK3, increased basal dCK activity more than two-fold. Two specific inhibitors of the MAPK/ERK pathway, PD-98059 and U-0126, also enhanced dCK activity. These data suggest that the JAK/MAPK pathway could be involved in the regulation of dCK. Moreover, we show that the activity of dCK, raised by CdA, can return to its initial level by treatment with protein phosphatase-2A (PP2A). Accordingly, dCK activity in intact cells increased upon incubation with okadaic acid (OA) at concentrations that should inhibit PP2A, but not protein phosphatase-1. Activation of dCK by protein kinase inhibitors and OA was also observed in CCRF-CEM cells and in chronic lymphocytic leukemia B-lymphocytes, suggesting a general mechanism of post-translational regulation of dCK, which could be exploited to enhance the activation of antileukemic nucleoside analogues.     

A COX-2 inhibitor nimesulide analog selectively induces apoptosis in Her2 overexpressing breast cancer cells via cytochrome c dependent mechanisms

Epidemiological and animal model studies have suggested that non-steroidal anti-inflammatory drugs (NSAIDs) can act as chemopreventive agents. The cyclooxygenase-2 (COX-2) inhibitor nimesulide shows anti-cancer effect in different type of cancers. In the current study, five breast carcinoma cell lines were used to explore the anti-cancer mechanisms of a nimesulide derivative compound 76. The compound dose dependently suppressed SKBR-3, BT474 and MDA-MB-453 breast cancer cell proliferation with IC₅₀ of 0.9 μM, 2.2 μM and 4.0 μM, respectively. However, it needs much higher concentrations to inhibit MCF-7 and MDA-MB-231 breast cancer cell growth with IC₅₀ at 22.1 μM and 19.6 μM, respectively. Further investigation reveals that compound 76 induced apoptosis in SKBR-3 and BT474 cells. Since these cells are Her2 overexpressing cells, the Her2 intracellular signaling pathways were examined after the treatment. There was no significant changing of kinase activity. However, the cytochrome c release assay indicated that the apoptosis induced by the compound was mediated by the mitochondria. These results suggest that compound 76 selectively induce apoptosis in Her2 overexpressing breast cancer cells through the mitochondria, and could be used as a lead to design more potent derivatives.     

Gallic acid inhibits migration and invasion in human osteosarcoma U-2 OS cells through suppressing the matrix metalloproteinase-2/-9, protein kinase B (PKB) and PKC signaling pathways

Advanced cancer is a multifactorial disease which complicates treatment if the cancer cells have metastasized calling for the targeting of multiple cellular pathways. Gallic acid (GA) is known to possess multiple pharmacological activity including antitumor effects. This study investigated the mechanisms for the anticancer properties of GA on migration and invasion of human osteosarcoma U-2 OS cells. The migration and invasion in U-2 OS cells were determined by a Boyden chamber transwell assay. The expression levels and activities of MMP-2 and MMP-9 were measured by Western blotting, real-time PCR and gelatin zymography assays. All examined proteins levels from Western blotting indicated that GA decreased the protein levels of GRB2, PI3K, AKT/PKB, PKC, p38, ERK1/2, JNK, NF-κB p65 in U-2 OS cells. GA also inhibited the activities of AKT, IKK and PKC by in vitro kinase assay. GA suppressed the migration and invasive ability of U-2 OS cells, and it decreased MMP-2 and MMP-9 protein and mRNA levels and secreted enzyme activities in vitro. These results suggest that potential signaling pathways of GA-inhibited migration and invasion in U-2 OS cells may be due to down-regulation of PKC, inhibition of mitogen-activated protein kinase (MAPK) and PI3K/AKT, resulting in inhibition of MMP-2 and MMP-9 expressions.     

Multiple defects in negative regulation of the PKB/Akt pathway sensitise human cancer cells to the antiproliferative effect of non-steroidal anti-inflammatory drugs

Antitumorigenic effects of non-steroidal anti-inflammatory drugs (NSAIDs) are well established in several types of cancer disease. However, the mechanisms driving these processes are not understood in all details. In our study, we observed significant differences in sensitivity of cancer epithelial cell lines to COX-independent antiproliferative effects of NSAIDs. The prostate cancer cell line LNCaP, lacking both critical enzymes in the negative control of PKB/Akt activation, PTEN and SHIP2, was the most sensitive to these effects, as assessed by analysing the cell cycle profile and expression of cell cycle regulating proteins. We found that p53 protein and its signalling pathway is not involved in early antiproliferative action of the selected NSAID—indomethacin. RNAi provided evidence for the involvement of p21^Cip1/Waf1, but not GDF-15, in antiproliferative effects of indomethacin in LNCaP cells. Interestingly, we also found that indomethacin activated PKB/Akt and induced nuclear localisation of p21^Cip1/Waf1 and Akt2 isoform. Our results are in agreement with other studies and suggest that maintaining of the p21^Cip1/Waf1 level and its intracellular localisation might be influenced by Akt2. Knock-down of SHIP2 by RNAi in PTEN negative prostate and colon cancer cell lines resulted in higher sensitivity to antiproliferative effects of indomethacin. Our data suggest novel mechanisms of NSAIDs antiproliferative action in cancer epithelial cells, which depends on the status of negative regulation of the PKB/Akt pathway and the isoform-specific action of Akt2. Thus, unexpectedly, multiple defects in negative regulation of the PKB/Akt pathway may contribute to increased sensitivity to chemopreventive effects of these widely used drugs.     

表皮生长因子受体酪氨酸激酶抑制剂治疗非小细胞肺癌相关不良反应研究进展

表皮生长因子受体酪氨酸激酶抑制剂（EGFR—TKI）治疗非小细胞肺癌（NSCLC）有较好疗效,目前临床常用药物为吉非替尼,厄洛替尼和埃克替尼。随着EGFR—TKI在临床的广泛应用,关于其不良反应的研究也不断深入。EGFR—TKI主要不良反应为皮疹、甲沟炎、毛发改变、腹泻、肝脏损害和间质性肺疾病等。引起不良反应的机制大多不明确。对于较常见的皮疹、甲沟炎等不良反应,较轻时可给予对症处理,严重时应减量或停药;对于较严重的肝脏损害或间质性肺疾病,给予对症治疗的同时要定期检测肝、肺功能。