Activated epidermal growth factor receptor-Stat-3 signaling promotes tumor survival in vivo in non-small cell lung cancer

Silencing of the transcription factor STAT3 sensitizes lung cancer cells to DNA damaging drugs, but not to TNFα- and NK cytotoxicity

Transcription factor STAT3 (Signal Transducers and Activators of Transcription 3) is persistently active in human tumors and may contribute to tumor progression. Inhibition of STAT3 expression/activity could be a good strategy to modulate tumor cell survival and responses to cancer chemotherapeutics or immune cytotoxicity. We silenced STAT3 expression in human A549 lung cancer cells to elucidate its role in cell survival and resistance to chemotherapeutics, TNFα and natural killer (NK)-mediated cytotoxicity. We demonstrate that STAT3 is not essential for basal survival and proliferation of A549 cancer cells. Stable silencing of STAT3 expression sensitized A549 cells to DNA damaging chemotherapeutics doxorubicin and cisplatin in a p53-independent manner. Sensitization to DNA damage-inducing chemotherapeutics could be due to down-regulation of the Bcl-xL expression in STAT3 depleted cells. In contrast, knockdown of STAT3 in cancer cells did not modulate responses to TNFα and NK-mediated cytotoxicity. We found that STAT3 depletion increased the NFκB activity likely providing the compensatory, pro-survival signal. The treatment with TNFα, but not doxorubicin, enhanced this effect. We conclude that STAT3 is not crucial for the control of basal cell proliferation and survival of lung carcinoma cells but modulates susceptibility to DNA damaging chemotherapeutics by regulation of intrinsic pro-survival pathways.

Modeling of tumor progression in NSCLC and intrinsic resistance to TKI in loss of PTEN expression

EGFR signaling plays a very important role in NSCLC. It activates Ras/ERK, PI3K/Akt and STAT activation pathways. These are the main pathways for cell proliferation and survival. We have developed two mathematical models to relate to the different EGFR signaling in NSCLC and normal cells in the presence or absence of EGFR and PTEN mutations. The dynamics of downstream signaling pathways vary in the disease state and activation of some factors can be indicative of drug resistance. Our simulation denotes the effect of EGFR mutations and increased expression of certain factors in NSCLC EGFR signaling on each of the three pathways where levels of pERK, pSTAT and pAkt are increased. Over activation of ERK, Akt and STAT3 which are the main cell proliferation and survival factors act as promoting factors for tumor progression in NSCLC. In case of loss of PTEN, Akt activity level is considerably increased. Our simulation results show that in the presence of erlotinib, downstream factors i.e. pAkt, pSTAT3 and pERK are inhibited. However, in case of loss of PTEN expression in the presence of erlotinib, pAkt level would not decrease which demonstrates that these cells are resistant to erlotinib.

Curcumin: a novel Stat3 pathway inhibitor for chemoprevention of lung cancer

Multiple studies from independent groups find evidence for signal transducer and activator of transcription 3 (Stat3) activation in nearly 50% of lung cancers, suggesting a functional role for this target in subsets of lung cancer. On the basis of the existing evidence, we hypothesized that bioavailable curcuminoid complex may modulate lung carcinogenesis, primarily by inhibiting Stat3 activation. With the safety of this being botanically well established, the objective of these studies was to test our hypothesis in vitro and in vivo in an effort to inform the design of a phase II chemoprevention trial in former smokers. We treated non-tumor-derived, normal (but immortalized) human bronchial epithelial cells (AALE) (Lundberg et al., 2002; Pillai et al., 2011) and lung adenocarcinoma-derived cells (H441) with bioactive curcumin C3 complex. Asynchronous cells in each case were treated with curcumin for 24 h, followed by immunoblotting for Stat3 and activated Stat3-P, prior signal of which was used for normalization. We also completed a preclinical trial in which 12 mice were randomly divided into three groups and subjected to 3 days or 9 days of curcumin intraperitoneal injections, followed by analysis of lung tissues for Stat3-P changes and growth suppressive effects of the curcumin. The growth suppressive effects were measured using Cyclin D1 and the replicative helicase subunit, Mcm2, as surrogates for the proliferative capacity of the tissues. In-vitro studies with curcuminoid complex demonstrated that the activity of Stat3 in both normal bronchoepithelial cells and lung cancer-derived cells is sensitive to curcumin exposure. In a dose-dependent manner, curcumin treatment resulted in significant suppression of Stat3 phosphorylation and reduction in the proliferative capacity of both cell types. In the preclinical trial with rodent models, curcumin reduced Stat3-P and the proliferative markers CycD1 and Mcm2 in mice lung tissues in vivo. These culture and preclinical studies indicate that the activity of the Stat3 pathway can be suppressed by curcumin treatment, concomitant with a reduction in cell proliferation, supporting our hypothesis that inhibition of the Stat3 pathway represents at least one important mechanism by which curcumin elicits its effects on the bronchoepithelium. These data provide a rationale for the use of curcumin as a promising chemopreventive agent in high-risk populations such as former smokers.

Tripartite motif containing 28 (Trim28) can regulate cell proliferation by bridging HDAC1/E2F interactions

BACKGROUND

Trim28 appears up-regulated in many cancers.

RESULTS

In early stage lung tumors high Trim28 correlates with increased overall survival and Trim28 reduces cell proliferation in model lung cancer cell lines through E2F interactions.

CONCLUSION

Trim28 may have a tumor suppressing role in the early stages of lung cancer.

SIGNIFICANCE

These results suggest a complex role for Trim28 in lung cancer. Trim28 is a poorly understood transcriptional co-factor with pleiotropic biological activities. Although Trim28 mRNA is found in many studies to be up-regulated in both lung and breast cancer tissues relative to normal adjacent tissue, we found that within a panel of early-stage lung adenocarcinomas high levels of Trim28 protein correlate with better overall survival. This surprising observation suggests that Trim 28 may have anti-proliferative activity within tumors. To test this hypothesis, we used shRNAi to generate Trim28-knockdown breast and lung cancer cell lines and found that Trim28 depletion led to increased cell proliferation. Likewise, overexpression of Trim28 led to decreased cell proliferation. Confocal microscopy indicated co-localization of E2F3 and E2F4 with Trim28 within the cell nucleus, and co-immunoprecipitation assays demonstrated that Trim28 can bind both E2F3 and E2F4. Trim28 overexpression inhibited the transcriptional activity of E2F3 and E2F4, whereas Trim28 deficiency enhanced their activity. Co-immunoprecipitations further indicated that Trim28 bridges an interaction between E2Fs 3 and 4 and HDAC1. Promoter-reporter assays demonstrated that the ability of HDAC1 to repress E2F3 and E2F4-driven transcription is dependent on Trim28. Trim28 depletion increased E2F3 and E2F4 DNA binding activity, as measured by chromatin-immunoprecipitation (ChIP) assays while simultaneously reducing HDAC1 binding. Finally, ChIP-ReChIP experiments demonstrated that Trim/E2F complexes exist on several E2F-regulated promoters. Taken together, these results suggest that Trim28 has anti-proliferative activity in lung cancers via repression of members of the E2F family that are critical for cell proliferation.

Keynote lecture in the 13th Japanese Society of Immunotoxicology (JSIT 2006) : -Pathophysiological Development and Immunotoxicology: what we have found from research related to silica and silicate such as asbestos-

Silica and silicates may disturb immune functions such as autoimmunity and tumor immunity, because people who are exposed to the materials sometimes develop autoimmune and malignant diseases, respectively. Although silica-induced disorders of autoimmunity have been explained as adjuvant-type effects of silica, more precise analyses are needed and should reflect the recent progress in immunomolecular findings. A brief summary of our investigations related to the immunological effects of silica/asbestos is presented. Recent advances in immunomolecular studies led to detailed analyses of the immunological effects of asbestos and silica. Both affect immuno-competent cells and these effects may be associated with the pathophysiological development of complications in silicosis and asbestos-exposed patients such as the occurrence of autoimmune disorders and malignant tumors, respectively. In addition, immunological analyses may lead to the development of new clinical tools for the modification of the pathophysiological aspects of diseases such as the regulation of autoimmunity or tumor immunity using cell-mediated therapies, various cytokines, and molecule-targeting therapies. In particular, as the incidence of asbestos-related malignancies is increasing and such malignancies have been a medical and social problem since the summer in 2005 in Japan, efforts should be focused on developing a cure for these diseases to eliminate the nation wide anxiety about these malignancies.

STAT3 inhibition, a novel approach to enhancing targeted therapy in human cancers (review)

Signal transducer and activator of transcription 3 (STAT3) regulates many critical functions in human normal and malignant tissues, such as differentiation, proliferation, survival, angiogenesis and immune function. Constitutive activation of STAT3 is implicated in a wide range of human cancers. As such, STAT3 has been studied as a tumour therapeutic target. This review aimed principally to summarise the updated research on STAT3 inhibition studies and their therapeutic potential in solid tumours. Recent literature associated with STAT3 inhibition was reviewed through PubMed and Medline database, followed by critical comparison and analysis. Constitutive activation of STAT3 has been identified as abnormal and oncogenic. The pathway of STAT3 activation and signal transduction identifies 3 approaches for inhibition: modulating upstream positive or negative regulators, regulating RNA (DN-STAT3, anti-sense RNA, siRNA and microRNA) or targeting STAT3 protein at different domains. The last approach using small molecule STAT3 inhibitors has been the most examined so far with both preclinical and clinical studies. Targeting STAT3 using a specific inhibitor may be a useful cancer treatment approach, with the potential for a broad clinical impact.

Curcumin blocks small cell lung cancer cells migration, invasion, angiogenesis, cell cycle and neoplasia through Janus kinase-STAT3 signalling pathway

Curcumin, the active component of turmeric, has been shown to protect against carcinogenesis and prevent tumor development. However, little is known about its anti-tumor mechanism in small cell lung cancer (SCLC). In this study, we found that curcumin can inhibit SCLC cell proliferation, cell cycle, migration, invasion and angiogenesis through suppression of the STAT3. SCLC cells were treated with curcumin (15 µmol/L) and the results showed that curcumin was effective in inhibiting STAT3 phosphorylation to downregulate of an array of STAT3 downstream targets ,which contributed to suppression of cell proliferation, loss of colony formation, depression of cell migration and invasion. Curcumin also suppressed the expression of proliferative proteins (Survivin, Bcl-X(L) and Cyclin B1), and invasive proteins (VEGF, MMP-2, MMP-7 and ICAM-1). Knockdown of STAT3 expression by siRNA was able to induce anti-invasive effects in vitro. In contrast, activation of STAT3 upstream of interleukin 6 (IL-6) leads to the increased cell proliferation ,cell survival, angiogenesis, invasion, migration and tumor growth. Our findings illustrate the biologic significance of IL-6/JAK/STAT3 signaling in SCLC progression and provide novel evidence that the pathway may be a new potential target for therapy of SCLC. It was concluded that curcumin is a potent agent in the inhibition of STAT3 with favorable pharmacological activity,and curcumin may have translational potential as an effective cancer therapeutic or preventive agent for SCLC.

STAT3 activation and aberrant ligand-dependent sonic hedgehog signaling in human pulmonary adenocarcinoma

The Sonic hedgehog (SHH) signaling and STAT3 pathways play important roles during carcinogenesis with possible interaction. To determine the association of the activation of SHH signaling pathway and STAT3 pathway in carcinogenesis of human non-small cell lung carcinomas (NSCLC), firstly we examined the expression of SHH signaling molecules including SHH, Gli1(glioma-associated oncogene homolog 1) and HHIP (Hh interacting protein), as well as p-STAT3 (phosphorylation at Tyr705) by immunohistochemistry in 87 cases of NSCLC, 12 atypical adenomatous hyperplasia (AAH) and 20 adjacent normal lung tissues. The expression of SHH, Gli1, HHIP and p-STAT3 was detected respectively in 87/87(100%), 74/87(85.1%), 75/87(86.2%) and 54/87(62.1%) of the NSCLC cases, but not in the adjacent normal lung parenchyma. Ligand-dependent SHH pathway activation and STAT3 signaling activation were observed in most cases of NSCLC, and the high SHH pathway activation rate and STAT3 activation rate were significantly higher in adenocarcinoma compared with squamous cell carcinomas and large cell carcinomas (P<0.05). Both SHH and STAT3 pathway activation level correlated with histological grade in adenocarcinoma, being higher in well-differentiated types (P<0.05). Furthermore, high SHH pathway activation and p-STAT3 expression were also detected in 10/12(83.3%) of AAH cases as well as in most cases of early-stage adenocarcinoma - adenocarcinoma in situ (AIS) and minimally invasive adenocarcinomas (MIA). Correlation analysis showed that p-STAT3 protein expression level was correlated positively with ligand-dependent activation level of SHH signaling in adenocarcinoma (r(s)=0.585, P=0.000) and AAH (r(s)=0.996, P=0.000). We speculated that activation of STAT3 could up-regulate SHH gene expression directly or indirectly, and thereby activated SHH signaling resulting in lung tumor cell ontogeny. To explore the interactional mechanism, we then performed serial transient co-transfection assay in human pulmonary adenocarcinoma cell line H441 cells, and the results confirmed STAT3 activation can up-regulate SHH gene expression indirectly. In conclusion, aberrant ligand-dependent SHH signaling activation occurs frequently in NSCLC. The signaling plays a more active role in adenocarcinoma, and is an early event in carcinogenesis of lung adenocarcinoma. The involvement of STAT3 pathway activation might function in inducing the process.

p14(ARF) inhibits the growth of lung adenocarcinoma cells harbouring an EGFR L858R mutation by activating a STAT3-dependent pro-apoptotic signalling pathway

Epidermal growth factor receptor (EGFR) stimulates proliferative and survival signals. Activating mutations of EGFR are involved in the aetiology and maintenance of the malignant phenotype of lung tumours. We previously described the frequent association of these mutations with the decreased expression of the p14(ARF) tumour suppressor, another common feature of lung cancer. Based on these data, we postulated that p14(ARF) could protect cells against untimely or excessive mitotic signals induced by mutant EGFR. In this study, we demonstrate that p14(ARF) promotes apoptosis in lung tumour cells harbouring the EGFR L858R mutation through the accumulation of phosphorylated signal transducer and activator of transcription 3 (STAT3) on Tyr 705 residue, which leads to Bcl-2 downregulation. Using siRNA against PTP-RT, the phosphatase that specifically targets Tyr 705 residue, we show that accumulation of pSTAT3-Tyr705 promotes EGFR L858R mutant cell death, thereby confirming the existence of a STAT3-dependent pro-apoptotic pathway in these cells. Finally, we show that the expression of the EGFR L858R mutant represses p14(ARF) expression and inhibits STAT3/Bcl-2 signalling. These results identify a novel link between the p14(ARF) and EGFR pathways and suggest that EGFR L858R counteracts the pro-apoptotic function of p14(ARF) by downregulating its expression to promote carcinogenesis.

Targeted therapy in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) of multi-factorial etiopathogenesis is rising worldwide. Treatment-associated toxicity problems and treatment failure in advanced disease stages with conventional therapies have necessitated a focus on alternative strategies. Molecular targeted therapy, with the potential for increased selectivity and fewer adverse effects, hold promise in the treatment of HNSCC. In an attempt to improve outcomes in HNSCC, targeted therapeutic strategies have been developed. These strategies are focusing on the molecular biology of HNSCC in an attempt to target selected pathways involved in carcinogenesis. Inhibiting tumor growth and metastasis by focusing on specific protein or signal transduction pathways or by targeting the tumor microenvironment or vasculature are some of the new approaches. Targeted agents for HNSCC expected to improve the effectiveness of current therapy include EGFR inhibitors (Cetuximab, Panitumumab, Zalutumumab), EGFR tyrosine kinase inhibitors (Gefitinib, Erloitinib), VEGFR inhibitors (Bevacizumab, Vandetanib), and various inhibitors of, e.g., Src-family kinase, PARP, proteasome, mTOR, COX, and heat shock protein. Moreover, targeted molecular therapy can also act as a complement to other existing cancer therapies. Several studies have demonstrated that the combination of targeting techniques with conventional current treatment protocols may improve the treatment outcome and disease control, without exacerbating the treatment related toxicities. Some of the targeted approaches have been proved as promising therapeutic potentials and are already in use, whereas remainder exhibits mixed result and necessitates further studies. Identification of predictive biomarkers of resistance or sensitivity to these therapies remains a fundamental challenge in the optimal selection of patients most likely to benefit from targeted treatment.

Enzastaurin has anti-tumour effects in lung cancers with overexpressed JAK pathway molecules

BACKGROUND

Enzastaurin, an oral serine-threonine kinase inhibitor, was initially developed as an ATP-competitive selective inhibitor against protein kinase Cβ. However, the mechanism by which enzastaurin contributes to tumourigenesis remains unclear.

METHODS

We analysed the anti-tumour effects of enzastaurin in 22 lung cancer cell lines to ascertain the potential for enzastaurin-based treatment of lung cancer. To identify molecules or signalling pathways associated with this sensitivity, we conducted a gene, receptor tyrosine kinases phosphorylation and microRNA expression profiling study on the same set of cell lines.

RESULTS

We identified eight genes by pathway analysis of molecules having gene-drug sensitivity correlation, and used them to build a support vector machine algorithm model by which sensitive cell lines were distinguished from resistant cell lines. Pathway analysis revealed that the JAK/STAT signalling pathway was one of the main ones involved in sensitivity to enzastaurin. Overexpression of JAK1 was observed in the sensitive cells by western blotting. Simultaneous administration of enzastaurin and JAK inhibitor inhibited enzastaurin-induced cell growth-inhibitory effect. Furthermore, lentiviral-mediated JAK1-overexpressing cells were more sensitive to enzastaurin than control cells.

CONCLUSION

Our results suggested that the JAK1 pathway may be used as a single predictive biomarker for enzastaurin treatment. The anti-tumour effect of enzastaurin should be evaluated in lung cancer with overexpressed JAK pathway molecules.

STAT3 is activated by JAK2 independent of key oncogenic driver mutations in non-small cell lung carcinoma

Constitutive activation of STAT3 is a common feature in many solid tumors including non-small cell lung carcinoma (NSCLC). While activation of STAT3 is commonly achieved by somatic mutations to JAK2 in hematologic malignancies, similar mutations are not often found in solid tumors. Previous work has instead suggested that STAT3 activation in solid tumors is more commonly induced by hyperactive growth factor receptors or autocrine cytokine signaling. The interplay between STAT3 activation and other well-characterized oncogenic “driver” mutations in NSCLC has not been fully characterized, though constitutive STAT3 activation has been proposed to play an important role in resistance to various small-molecule therapies that target these oncogenes. In this study we demonstrate that STAT3 is constitutively activated in human NSCLC samples and in a variety of NSCLC lines independent of activating KRAS or tyrosine kinase mutations. We further show that genetic or pharmacologic inhibition of the gp130/JAK2 signaling pathway disrupts activation of STAT3. Interestingly, treatment of NSCLC cells with the JAK1/2 inhibitor ruxolitinib has no effect on cell proliferation and viability in two-dimensional culture, but inhibits growth in soft agar and xenograft assays. These data demonstrate that JAK2/STAT3 signaling operates independent of known driver mutations in NSCLC and plays critical roles in tumor cell behavior that may not be effectively inhibited by drugs that selectively target these driver mutations.

STAT3 Regulates Proliferation and Immunogenicity of the Ewing Family of Tumors In Vitro

The Ewing sarcoma family of tumors (ESFT) represents an aggressive spectrum of malignant tumour types with common defining histological and cytogenetic features. To evaluate the functional activation of signal transducer and activator of transcription 3 (STAT3) in ESFT, we evaluated its activation in primary tissue sections and observed the functional consequences of its inhibition in ESFT cell lines. STAT3 was activated (tyrosine 705-phosphorylated) in 18 out of 31 primary tumours (58%), either diffusely (35%) or focally (23%). STAT3 was constitutively activated in 3 out of 3 ESFT cell lines tested, and its specific chemical inhibition resulted in complete loss of cell viability. STAT3 inhibition in ESFT cell lines was associated with several consistent changes in chemokine profile suggesting a role of STAT3 in ESFT in both cell survival and modification of the cellular immune environment. Together these data support the investigation of STAT3 inhibitors for the Ewing family of tumors.

Interferon (alpha, beta and omega) receptor 2 is a prognostic biomarker for lung cancer

OBJECTIVES

It has been reported that the type I interferon receptor subunit, interferon (alpha, beta and omega) receptor 2 (IFNAR2), is overexpressed in several malignancies, primarily adenocarcinomas (ADCs); however, the biological significance of IFNAR2 in human lung cancer has not yet been studied.

METHODS

Immunohistochemical analysis of 113 surgically resected lung specimens was performed, and the results were evaluated in association with clinical variables, including survival. Serum concentrations of IFNAR2 were also determined by an enzyme-linked immunosorbent assay in 157 lung cancer patients and 164 healthy volunteers.

RESULTS

IFNAR2 overexpression was observed in all histological types of lung cancer examined. Furthermore, strong IFNAR2 expression was associated with shorter progression-free survival (PFS) and overall survival (OS) (p < 0.0001 and p = 0.0110, respectively) in non-small cell lung cancer patients. Multivariate analyses confirmed its independent prognostic value for PFS and OS (p < 0.0001 and p = 0.0222, respectively). IFNAR2 serum levels were also significantly higher in lung cancer patients than in healthy volunteers (p < 0.0001).

CONCLUSIONS

IFNAR2 overexpression was observed in various histological types of lung cancer, and appears to be associated with lung cancers that behave aggressively. The results of this study strongly support the potential of IFNAR2 to be a prognostic biomarker for lung cancer.

Prognostic significance of nuclear pSTAT3 in oral cancer

BACKGROUND

Aberrant nuclear accumulation of proteins influences tumor development and may predict biologic aggressiveness and disease prognosis. This study determined the prognostic significance of pSTAT3 (phosphorylayed signal transducer and activator of transcription 3) in oral squamous cell carcinomas (OSCCs).

METHODS AND RESULTS

Using immunohistochemistry, a significant increase in nuclear accumulation of pSTAT3 was observed in 49 of 90 leukoplakias (54.4%) and 63/94 OSCCs (67%) (p(trend) < .001). Increased pSTAT3 was associated with tumor stage (p = .01), nodal metastasis (p = .0018), and tobacco consumption (p = .004). Kaplan-Meier analysis demonstrated that OSCC with increased nuclear pSTAT3 showed significantly reduced disease-free survival (13 months), compared with the patients with no nuclear pSTAT3 expression (64 months, p = .019). Cox regression analysis revealed nuclear pSTAT3 as the most significant predictor of poor prognosis (p = .024, hazard ratio [HR] = 2.7).

CONCLUSIONS

Increased nuclear accumulation of pSTAT3 occurs in early premalignant stages and is a marker for poor prognosis of OSCC.

CK2 inhibitors enhance the radiosensitivity of human non-small cell lung cancer cells through inhibition of stat3 activation

CK2 interacts and phosphorylates >300 proteins, including Stat3, and is linked to a number of human cancers. Constitutively activated Stat3 has been reported in 50% of human lung cancers. Inhibition of CK2 activity can induce apoptosis and suppression of Stat3 activation in cancer cells. This study examined the effects of CK2 inhibitors on growth inhibition of lung cancer cells and the therapeutic potential on lung cancer. The CK2 inhibitor and radiation both suppressed cancer cell growth in a dose-dependent manner. Besides, the cytotoxic effect of irradiation could be augmented by CK2 inhibitors (p<0.05, two-way analysis of variance and Tukey's Honestly Significant Difference). Moreover, the growth inhibition of CK2 inhibitor and irradiation was both associated with suppression of Stat3 activation. Taken together, inhibition of CK2 activity appears to be a promising treatment strategy for non-small cell lung cancer and CK2 inhibition results in reduced Stat3 activation. Our data warrant further effort to develop CK2-targeted radiosensitizer for lung cancer treatment.

STAT6 expression in glioblastoma promotes invasive growth

BACKGROUND

Glioblastoma (GBM) is a highly aggressive malignant primary brain tumor, characterized by rapid growth, diffuse infiltration of cells into both adjacent and remote brain regions, and a generalized resistance to currently available treatment modalities. Recent reports in the literature suggest that Signal Transducers and Activators of Transcription (STATs) play important roles in the regulation of GBM pathophysiology.

METHODS

STAT6 protein expression was analyzed by Western blotting in GBM cell lines and by immunohistochemistry in a tissue microarray (TMA) of glioma patient tissues. We utilized shRNA against STAT6 to investigate the effects of prolonged STAT6 depletion on the growth and invasion of two STAT6-positive GBM cell lines. Cell proliferation was assessed by measuring (3)H-Thymidine uptake over time. Invasion was measured using an in vitro transwell assay in which cells invade through a type IV collagen matrix toward a chemoattractant (Fetal Bovine Serum). Cells were then stained and counted. Kaplan-Meyer survival curves were generated to show the correlation between STAT6 gene expression and patient survival in 343 glioma patients and in a subset of patients with only GBM. Gene expression microarray and clinical data were acquired from the Rembrandt 1 public data depository (https://caintegrator.nci.nih.gov/rembrandt/). Lastly, a genome-wide expression microarray analysis was performed to compare gene expression in wild-type GBM cells to expression in stable STAT6 knockdown clones.

RESULTS

STAT6 was expressed in 2 GBM cell lines, U-1242MG and U-87MG, and in normal astrocytes (NHA) but not in the U-251MG GBM cell line. In our TMA study, STAT6 immunostaining was visible in the majority of astrocytomas of all grades (I-IV) but not in normal brain tissue. In positive cells, STAT6 was localized exclusively in the nuclei over 95% of the time. STAT6-deficient GBM cells showed a reduction in (3)H-Thymidine uptake compared to the wild-type. There was some variation among the different shRNA- silenced clones, but all had a reduction in (3)H-Thymidine uptake ranging from 35%- 70% in U-1242MG and 40- 50% in U-87MG cells. Additionally, STAT6- depleted cells were less invasive than controls in our in vitro transmembrane invasion assay. Invasiveness was decreased by 25-40% and 30-75% in U-1242MG and U-87MG cells, respectively. The microarray analysis identified matrix metalloproteinase 1 (MMP-1) and urokinase Plasminogen activator (uPA) as potential STA6 target genes involved in the promotion of GBM cell invasion. In a Kaplan-Meier survival curve based on Rembrandt 1 gene expression microarray and clinical data, there was a significant difference in survival (P < 0.05) between glioma patients with up- and down-regulated STAT6. Decreased STAT6 expression correlated with longer survival times. In two subsets of patients with either grade IV tumors (GBM) or Grade II/III astrocytomas, there was a similar trend that however did not reach statistical significance.

CONCLUSIONS

Taken together, these findings suggest a role for STAT6 in enhancing cell proliferation and invasion in GBM, which may explain why up-regulation of STAT6 correlates with shorter survival times in glioma patients. This report thus identifies STAT6 as a new and potentially promising therapeutic target.

Multifaceted intervention by the Hsp90 inhibitor ganetespib (STA-9090) in cancer cells with activated JAK/STAT signaling

There is accumulating evidence that dysregulated JAK signaling occurs in a wide variety of cancer types. In particular, mutations in JAK2 can result in the constitutive activation of STAT transcription factors and lead to oncogenic growth. JAK kinases are established Hsp90 client proteins and here we show that the novel small molecule Hsp90 inhibitor ganetespib (formerly STA-9090) exhibits potent in vitro and in vivo activity in a range of solid and hematological tumor cells that are dependent on JAK2 activity for growth and survival. Of note, ganetespib treatment results in sustained depletion of JAK2, including the constitutively active JAK2^V617F mutant, with subsequent loss of STAT activity and reduced STAT-target gene expression. In contrast, treatment with the pan-JAK inhibitor P6 results in only transient effects on these processes. Further differentiating these modes of intervention, RNA and protein expression studies show that ganetespib additionally modulates cell cycle regulatory proteins, while P6 does not. The concomitant impact of ganetespib on both cell growth and cell division signaling translates to potent antitumor efficacy in mouse models of xenografts and disseminated JAK/STAT-driven leukemia. Overall, our findings support Hsp90 inhibition as a novel therapeutic approach for combating diseases dependent on JAK/STAT signaling, with the multimodal action of ganetespib demonstrating advantages over JAK-specific inhibitors.

Inhibition of JAK2 signaling by TG101209 enhances radiotherapy in lung cancer models

INTRODUCTION

Persistent STAT3 activation contributes to lung carcinogenesis. Survivin, one of STAT3-regulated genes, is antiapoptotic and confers cancer radioresistance.

METHODS

We tested whether TG101209, a small-molecule inhibitor of JAK2 (a STAT3-activating tyrosine kinase), affected survivin expression and sensitized lung cancer to radiation. We investigated whether inhibition of JAK2 signaling with TG101209 can be used to reduce survivin expression and enhance radiosensitivity of lung cancer cells in vitro and tumor growth delay in vivo. JAK2 downstream signaling, including PI3-K/Akt and Ras/MAPK/ERK pathways, was also explored.

RESULTS

TG101209 inhibited STAT3 activation and survivin expression and sensitized HCC2429 (dose enhancement ratio = 1.34, p = 0.002) and H460 (dose enhancement ratio = 1.09, p = 0.006) cells to radiation in clonogenic assays. Radiation promoted phospho-Akt and phospho-ERK in H460 cells, while their levels were unchanged in HCC2429. After treatment with TG101209, phospho-ERK protein levels were reduced in both HCC2429 and H460 cells. HCC2429 cells transfected with KRAS-12V mutant were more resistant to radiation- and TG101209-induced apoptosis than wild-type control cells. In vivo, addition of TG101209 to radiation in lung xenografts produced a significant tumor growth delay (>10 days) compared with radiation alone and was well tolerated. Immunohistochemistry staining of tumor sections showed that TG101209 increased apoptosis and decreased cell proliferation and vascular density, suggesting that TG101209 also has antiangiogenic effects.

CONCLUSIONS

TG101209 enhanced the effects of radiation in lung cancer in vitro and in vivo. This study suggests the potential utility of selecting lung cancer patients according to KRAS mutation status for future clinical trials testing combination of TG101209 and radiotherapy.

Clinical significance of pretreatment C-reactive protein in patients with advanced nonsquamous, non-small cell lung cancer who received gefitinib

PURPOSE

We examined patients with advanced nonsquamous, non-small cell lung cancer (NSCLC) to evaluate epidermal growth factor receptor (EGFR) mutation status and serum C-reactive protein (CRP) for their associations with response to gefitinib therapy and for prognostic impacts.

METHODS

Serum levels of CRP from 79 Japanese patients with advanced nonsquamous NSCLC were measured before the start of gefitinib. We used the peptic nucleic acid-locked nucleic acid clamp method to determine their EGFR somatic mutation status. We evaluated the relationship between each independent clinicopathological variable and the response to gefitinib therapy and the risk factors associated with prognosis.

RESULTS

Having CRP-positive serum and having wild-type EGFR were both independent negative predictive factors for the response to gefitinib treatment by multivariate logistic regression model analysis. Having CRP-positive serum and having wild-type EGFR were significant independent negative prognostic factors for survival based on multivariate analysis.

CONCLUSIONS

Having CRP-positive serum predicted a lack of response to gefitinib therapy independent of EGFR mutational status. Both CRP-positive serum and wild-type EGFR were independent poor prognostic factors in patients with nonsquamous NSCLC who received gefitinib therapy.

The role of chalcones in suppression of NF-κB-mediated inflammation and cancer

Although consumption of fruits, vegetables, spices, cereals and pulses has been associated with lower incidence of cancer and other chronic diseases, how these dietary agents and their active ingredients minimize these diseases, is not fully understood. Whether it is oranges, kawa, hops, water-lilly, locorice, wax apple or mulberry, they are all connected by a group of aromatic ketones, called chalcones (1,3-diaryl-2-propen-1-ones). Some of the most significant chalcones identified from these plants include flavokawin, butein, xanthoangelol, 4-hydroxyderricin, cardamonin, 2',4'-dihydroxychalcone, isoliquiritigenin, isosalipurposide, and naringenin chalcone. These chalcones have been linked with immunomodulation, antibacterial, antifungal, antiviral, anti-inflammatory, antioxidant, anticancer, and antidiabetic activities. The current review, however, deals with the role of various chalcones in inflammation that controls both the immune system and tumorigenesis. Inflammatory pathways have been shown to mediate the survival, proliferation, invasion, angiogenesis and metastasis of tumors. How these chalcones modulate inflammatory pathways, tumorigenesis and immune system is the focus of this review.

A pilot study of preoperative gefitinib for early-stage lung cancer to assess intratumor drug concentration and pathways mediating primary resistance

BACKGROUND

Targeted agents such as tyrosine kinase inhibitors have been extensively studied in preclinical systems and in advanced-stage patients. Little is known about levels of kinase inhibitors found in tumors as opposed to plasma. Similarly, effects of inhibitors on tumor signaling pathways in patient-based materials are unclear. To explore these questions, we conducted a trial of a brief course of preoperative gefitinib, an epidermal growth factor receptor (EGFR) inhibitor, in early-stage non-small cell lung cancer.

METHODS

Patient with early-stage non-small cell lung cancer received 4 weeks of gefitinib 250 mg daily before surgical resection. Pre- and posttreatment computerized tomography scans and positron emission tomography scans were used to assess clinical response. Gefitinib and surgical toxicity were evaluated. Tumor tissue was evaluated for gefitinib levels and was compared with plasma gefitinib levels. Activated signaling molecules including EGFR, STAT3, ERK, and AKT were examined in surgically resected tumor tissue.

RESULTS

Twenty-three patients participated in the study, and all had surgical resection of tumors. No toxicities unrelated to known effects of gefitinib or surgery were encountered. Twenty-two patients had stable disease, and one had progression in tumor size. There was no correlation with positron emission tomography response and computerized tomography response. Tumor levels of gefitinib were approximately 40-fold higher than plasma levels, indicating potential tumor concentration of gefitinib. Tyrosine phosphorylated STAT3 was abundant in the surgically resected tumor tissue, indicating potential role in primary resistance in vivo.

CONCLUSIONS

This study confirms previous preclinical observations that tumor tissues concentrate gefitinib. Persistent STAT3 may be leading to primary resistance to EGFR inhibitors in vivo.

Prognostic value of co-expression of STAT3, mTOR and EGFR in gastric cancer

Signal transducer and activator of transcription 3 (STAT3), the mammalian target of rapamycin (mTOR) and epidermal growth factor receptor (EGFR), proteins that mediate intracellular signaling related to cell growth, proliferation and differentiation, have received considerable interest as possible targets for cancer treatment. We examined whether the expression of STAT3, mTOR and EGFR correlates with clinicopathological features and patient outcome in gastric cancer. Tumor samples were obtained from 126 patients with gastric adenocarcinomas who underwent a radical gastrectomy between 1999 and 2002. The expression of phosphorylated STAT3 (p-STAT3), p-mTOR and EGFR was analyzed by immunohistochemical staining. The relations of these to clinicopathological factors and outcomes were assessed. The expression of p-STAT3 p-mTOR and EGFR positively correlated with the following variables related to tumor progression: the depth of tumor invasion (T1 vs. T2-4; p<0.001, p=0.036 and p<0.001, respectively), lymph node involvement (p=0.008, p=0.027 and p=0.007) and tumor stage (I vs. II-IV; p<0.001, p=0.041 and p<0.001). The expression of p-STAT3 and EGFR was significantly related to distant metastasis and recurrence (p=0.001 and p=0.039), as well as significantly poorer disease-specific survival (DSS; p=0.0018 and p=0.026). The expression of p-STAT3 was a marginally non-significant prognostic factor for DSS (hazard ratio=2.0, 95% CI 0.91-4.5, p=0.082). Increasing expression of p-STAT3, p-mTOR and EGFR was associated with progressively worse DSS. Interactions among p-STAT3, p-mTOR and EGFR may play an important role in tumor progression and outcomes in patients with gastric cancer.

JAK1 activates STAT3 activity in non-small-cell lung cancer cells and IL-6 neutralizing antibodies can suppress JAK1-STAT3 signaling

Members of the signal transducer and activator of transcription (STAT) family of transcription factors are potential targets for the treatment and prevention of cancers including non-small-cell lung cancer. STAT proteins can be phosphorylated and activated by diverse upstream kinases including cytokine receptors and tyrosine kinases. We examined STAT protein activation in lung cancer cell lines including those with activating mutations in the EGFR and examined upstream kinases responsible for STAT3 phosphorylation and activation using small molecules, antibodies, and RNA interference. We found more pronounced STAT3 activation in cells with activating EGFR mutations, yet inhibition of EGFR activity had no effect on STAT3 activation. Inhibition of JAK1 with small molecules or RNA interference resulted in loss of STAT3 tyrosine phosphorylation and inhibition of cell growth. An interleukin-6 neutralizing antibody, siltuximab (CNTO 328) could inhibit STAT3 tyrosine phosphorylation in a cell-dependent manner. Siltuximab could completely inhibit STAT3 tyrosine phosphorylation in H1650 cells, and this resulted in inhibition of lung cancer cell growth in vivo. Combined EGFR inhibition with erlotinib and siltuximab resulted in dual inhibition of both tyrosine and serine STAT3 phosphorylation, more pronounced inhibition of STAT3 transcriptional activity, and translated into combined effects on lung cancer growth in a mouse model. Our results suggest that JAK1 is responsible for STAT3 activation in lung cancer cells and that indirect attacks on JAK1-STAT3 using an IL-6 neutralizing antibody with or without EGFR inhibition can inhibit lung cancer growth in lung cancer subsets.

Reverse phase protein microarrays for clinical applications

Phosphorylated proteins represent one of the most important constituents of the proteome and are under intense analysis by the biotechnology and pharmaceutical industry because of their central role for cellular signal transduction. Indeed, alterations in cellular signaling and control mechanisms that modulate signal transduction, functionally underpin most human cancers today. Beyond their central role as the causative components of tumorigenesis, these proteins have become an important research focus for discovery of predictive and prognostic biomarkers. Consequently, these pathway constituents comprise a powerful biomarker subclass whereby the same analyte that provides prediction and/or prognosis is also the drug target itself: a theranostic marker. Reverse phase protein microarrays have been developed to generate a functional patient-specific circuit "map" of the cell signaling networks based directly on cellular analysis of a biopsy specimen. This patient-specific circuit diagram provides key information that identifies critical nodes within aberrantly activated signaling that may serve as drug targets for individualized or combinatorial therapy. The protein arrays provide a portrait of the activated signaling network by the quantitative analysis of the phosphorylated, or activated, state of cell signaling proteins. Based on the growing realization that each patient's tumor is different at the molecular level, the ability to measure and profile the ongoing phosphoprotein biomarker repertoire provides a new opportunity to personalize therapy based on the patient-specific alterations.

The role of the c-Jun N-terminal kinase 2-α-isoform in non-small cell lung carcinoma tumorigenesis

The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase family and have been implicated in tumorigenesis. One isoform in particular, JNK2α, has been shown to be frequently activated in primary brain tumors, to enhance several tumorigenic phenotypes and to increase tumor formation in mice. As JNK is frequently activated in non-small cell lung carcinoma (NSCLC), we investigated the role of the JNK2α isoform in NSCLC formation by examining its expression in primary tumors and by modulating its expression in cultured cell lines. We discovered that 60% of the tested primary NSCLC tumors had three-fold higher JNK2 protein and two- to three-fold higher JNK2α mRNA expression than normal lung control tissue. To determine the importance of JNK2α in NSCLC progression, we reduced JNK2α expression in multiple NSCLC cell lines using short hairpin RNA. Cell lines deficient in JNK2α had decreased cellular growth and anchorage-independent growth, and the tumors were four-fold smaller in mass. To elucidate the mechanism by which JNK2α induces NSCLC growth, we analyzed the JNK substrate, signal transducer and activator of transcription 3 (STAT3). Our data demonstrates for the first time that JNK2α can regulate the transcriptional activity of STAT3 by phosphorylating the Ser727 residue, thereby regulating the expression of oncogenic genes, such as c-Myc. Furthermore, reintroduction of JNK2α2 or STAT3 restored the tumorigenicity of the NSCLC cells, demonstrating that JNK2α is important for NSCLC progression. Our studies reveal a novel mechanism in which phosphorylation of STAT3 is mediated by a constitutively active JNK2 isoform, JNK2α.

Patterns of basal signaling heterogeneity can distinguish cellular populations with different drug sensitivities

Phenotypic heterogeneity has been widely observed in cellular populations. However, the extent to which heterogeneity contains biologically or clinically important information is not well understood. Here, we investigated whether patterns of basal signaling heterogeneity, in untreated cancer cell populations, could distinguish cellular populations with different drug sensitivities. We modeled cellular heterogeneity as a mixture of stereotyped signaling states, identified based on colocalization patterns of activated signaling molecules from microscopy images. We found that patterns of heterogeneity could be used to separate the most sensitive and resistant populations to paclitaxel within a set of H460 lung cancer clones and within the NCI-60 panel of cancer cell lines, but not for a set of less heterogeneous, immortalized noncancer human bronchial epithelial cell (HBEC) clones. Our results suggest that patterns of signaling heterogeneity, characterized as ensembles of a small number of distinct phenotypic states, can reveal functional differences among cellular populations.

The contribution of cetuximab in the treatment of recurrent and/or metastatic head and neck cancer

Recurrent and/or metastatic squamous cell carcinoma of the head and neck (HNSCC) continues to be a source of significant morbidity and mortality worldwide. Agents that target the epidermal growth factor receptor (EGFR) have demonstrated beneficial effects in this setting. Cetuximab, a monoclonal antibody against the EGFR, improves locoregional control and overall survival when used as a radiation sensitizer in patients with locoregionally advanced HNSCC undergoing definitive radiation therapy with curative intent. Cetuximab is also active as monotherapy in patients whose cancer has progressed on platinum-containing therapy. In the first-line setting for incurable HNSCC, cetuximab added to platinum-based chemotherapy significantly improves overall survival compared with standard chemotherapy alone. These positive results have had a significant impact on the standard of care for advanced HNSCC. In this review, we will discuss the mechanism of action, clinical data and common toxicities that pertain to the use of cetuximab in the treatment of advanced incurable HNSCC.

RNA interference against hepatic epidermal growth factor receptor has suppressive effects on liver regeneration in rats

Liver regeneration after a two-thirds partial hepatectomy (PHx) is a complex process requiring interaction and cooperation of many growth factors and cytokines and cross talk between multiple pathways. Along with hepatocyte growth factor and its receptor MET (HGF-MET), the epidermal growth factor receptor (EGFR) signaling pathway is activated within 60 minutes after PHx. To investigate the role of EGFR in liver regeneration, we used two EGFR-specific short hairpin silencing RNAs to inhibit EGFR expression in regenerating normal rat liver. Suppression of EGFR mRNA and protein was evident in treated rats. There was also a demonstrable decrease but not complete elimination of bromo-deoxyuridine incorporation and mitoses at 24 hours after PHx. In addition, we observed up-regulation of MET and Src as well as activation of the ErbB-3-ErbB-2-PI3K-Akt pathway and down-regulation of STAT 3, cyclin D1, cyclin E1, p21, and C/EBP beta. The decrease in the ratio of C/EBP alpha to C/EBP beta known to occur after PHx was offset in shEGFR-treated rats. Despite suppression of hepatocyte proliferation lasting into day 3 after PHx, liver weight restoration occurred. Interestingly, hepatocytes in shEGFR-treated rats were considerably larger when compared with ScrRNA-treated controls. The data indicate that although the MET and EGFR pathways are similar, the contributions made by MET and EGFR are unique and are not compensated by each other or other cytokines.

Defining the role of the JAK-STAT pathway in head and neck and thoracic malignancies: implications for future therapeutic approaches

Although the role of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway has been most extensively studied in hematopoietic cells and hematologic malignancies, it is also activated in epithelial tumors, including those originating in the lungs and head and neck. The canonical pathway involves the activation of JAK following ligand binding to cytokine receptors. The activated JAKs then phosphorylate STAT proteins, leading to their dimerization and translocation into the nucleus. In the nucleus, STATs act as transcription factors with pleiotropic downstream effects. STATs can be activated independently of JAKs, most notably by c-Src kinases. In cancer cells, STAT3 and STAT5 activation leads to the increased expression of downstream target genes, leading to increased cell proliferation, cell survival, angiogenesis, and immune system evasion. STAT3 and STAT5 are expressed and activated in head and neck squamous cell carcinoma (HNSCC) where they contribute to cell survival and proliferation. In HNSCC, STATs can be activated by a number of signal transduction pathways, including the epidermal growth factor receptor (EGFR), alpha7 nicotinic receptor, interleukin (IL) receptor, and erythropoietin receptor pathways. Activated STATs are also expressed in lung cancer, but the biological effects of JAK/STAT inhibition in this cancer are variable. In lung cancer, STAT3 can be activated by multiple pathways, including EGFR. Several approaches have been used to inhibit STAT3 in the hopes of developing an antitumor agent. Although several STAT3-specific agents are promising, none are in clinical development, mostly because of drug delivery and stability issues. In contrast, several JAK inhibitors are in clinical development. These orally available, ATP-competitive, small-molecule kinase inhibitors are being tested in myeloproliferative disorders. Future studies will determine whether JAK inhibitors are useful in the treatment of HNSCC or lung cancer.

Constitutive activation of signal transducer and activator of transcription 3 in epithelial ovarian carcinoma

AIM

To investigate the expressions of signal transducer and activator of transcription 3 (Stat3) and tyrosine-activated Stat3 (p-Stat3) in epithelial ovarian carcinoma (EOC) and their relationships with clinical pathological parameters or prognosis.

METHODS

Immunohistochemical methods were used to detect the expressions of Stat3 and p-Stat3 in EOC, benign ovarian tumors and normal ovarian tissues, after which an analysis of results with clinical pathological or prognosis was given.

RESULTS

The expressions of Stat3 and p-Stat3 in EOC were significantly higher than in normal ovarian epithelial tissues or benign ovarian tumor tissues (P < 0.0125) and the expression of Stat3 protein was highly correlated with the expression of p-Stat3 protein (P < 0.01). The positive rate of Stat3 in stages of III and IV (96.9%) was significantly higher than in stages of I and II (72.2%) (P < 0.05). Meanwhile, p-Stat3 expression was significantly correlated with disease stage, degree of differentiation and lymph node metastasis. Along with higher clinical stage (P < 0.05), p-Stat3 expression was gradually increased. The p-Stat3 expression was negatively correlated with the prognosis of EOC patients (P < 0.01).

CONCLUSION

Overexpression and overactivation of Stat3 was found in EOC tissues, and the constitutive activation of Stat3 signaling pathway may play an important role in the invasion and prognosis of EOC.

Clinical impact of phosphorylated signal transducer and activator of transcription 3, epidermal growth factor receptor, p53, and vascular endothelial growth factor receptor 1 expression in resected adenocarcinoma of lung by using tissue microarray

BACKGROUND

The signal transducer and activator of transcription 3 (STAT3) play a key role in the downstream pathway of the epidermal growth factor receptor (EGFR) in nonsmall cell lung cancer and promote cell proliferation, invasion, and angiogenesis. The clinical significance of phosphorylated STAT3 (pSTAT3), EGFR, p53, and vascular endothelial growth factor receptor 1 (VEGFR-1) expression in patients with completely resected lung adenocarcinoma was evaluated to determine the effects of pSTAT3 in tumor angiogenesis and proliferation.

METHODS

The expressions of pSTAT3, EGFR, p53, and VEGFR-1 were evaluated by immunohistochemical staining of tissue microarrays from 162 samples of resected lung adenocarcinoma.

RESULTS

The median age of the 162 patients was 62 years, the median disease-free survival was 41.7 months, and the median OS (OS) was 80.2 months. Expression of pSTAT3, EGFR, p53, and VEGFR-1 was detected in 51.2%, 71%, 35.2%, and 35.2% of the samples, respectively. pSTAT3 expression was correlated significantly with VEGFR-1 expression (P = .025). The coexpression of pSTAT3 and VEGFR-1 was correlated with increased lymph node involvement (P = .021) and a trend toward a short OS (P = .085). In multivariate analysis, the expression levels of p53 and VEGFR-1 were identified as independent prognostic factors that affected OS.

CONCLUSIONS

The results of this study suggested that pSTAT3 and VEGFR-1 expression may play roles in the tumor progression and angiogenesis of lung adenocarcinoma. Further studies are needed, however, to uncover the detailed mechanisms that underlie the roles of these proteins in lung adenocarcinoma.

Clinical outcomes in non-small-cell lung cancer patients with EGFR mutations: pooled analysis

Non-small-cell lung cancer (NSCLC) with mutations in the epidermal growth factor receptor (EGFR) is a distinct subgroup of NSCLCs that is particularly responsive to EGFR tyrosine-kinase inhibitors (TKIs). A weighted pooled analysis of available studies was performed to evaluate clinical outcome in patients with EGFR-mutated NSCLC who were treated with chemotherapy or EGFR TKIs. Median progression-free survival (PFS) times were pooled from prospective or retrospective studies that evaluated chemotherapy or single-agent EGFR TKIs (erlotinib or gefitinib) in patients with NSCLC and EGFR mutations. Among the studies identified for inclusion in the analysis, 12 evaluated erlotinib (365 patients), 39 evaluated gefitinib (1069 patients) and 9 evaluated chemotherapy (375 patients). Across all studies, the most common EGFR mutations were deletions in exon 19 and the L858R substitution in exon 21. In the weighted pooled analysis, the overall median PFS was 13.2 months with erlotinib, 9.8 months with gefitinib and 5.9 months with chemotherapy. Using a two-sided permutation, erlotinib and gefitinib produced a longer median PFS versus chemotherapy, both individually (P= 0.000 and P= 0.002, respectively) and as a combined group (EGFR TKI versus chemotherapy, P= 0.000). EGFR TKIs appear to be the most effective treatment for patients with advanced EGFR-mutant NSCLC. Ongoing prospective trials comparing the efficacy of first-line chemotherapy and EGFR TKIs in EGFR-mutant disease should provide further insight into the most appropriate way to treat this specific group of patients.

Response to gefitinib and erlotinib in Non-small cell lung cancer: a restrospective study

BACKGROUND

In Non-small cell lung cancer (NSCLC), an overactive epidermal growth factor receptor (EGFR) pathway is a component of the malignant phenotype. Two tyrosine kinase inhibitors (TKIs) of EGFR, gefinitib and erlotinib, have been used with variable benefit.

METHODS

We have analyzed outcome data of a population of NSCLC patients that received these TKIs to determine the benefit derived and to define the clinical and molecular parameters that correlate with response. Tumor tissue from a subgroup of these patients was analyzed by immunohistochemistry to measure the expression level of EGFR and four activated (phosphorylated) members of the pathway, pEGFR, pERK, pAKT, and pSTAT3.

RESULTS

Erlotinib was slightly superior to gefitinib in all measures of response, although the differences were not statistically significant. The most robust clinical predictors of time to progression (TTP) were best response and rash (p < 0.0001). A higher level of pEGFR was associated with longer TTP, while the total EGFR level was not associated with response. Higher levels of pAKT and pSTAT3 were also associated with longer TTP. In contrast, a higher level of pERK1/2 was associated with shorter TTP.

CONCLUSION

These observations suggest the hypothesis that tumor cells that have activated EGFR pathways, presumably being utilized for survival, are clinically relevant targets for pathway inhibition. An accurate molecular predictive model of TKI response should include activated members of the EGFR pathway. TKIs may be best reserved for tumors expressing pEGFR and pAKT or pSTAT, and little pERK. In the absence of molecular predictors of response, the appearance of a rash and a positive first scan are good clinical indicators of response.

Inhibition of STAT-3 results in radiosensitization of human squamous cell carcinoma

BACKGROUND

Signal transducer and activator of transcription-3 (STAT-3) is a downstream component of the Epidermal Growth Factor Receptor (EGFr) signaling process that may facilitate the resistance of tumor cells to conventional cancer treatments. Studies were performed to determine if inhibition of this downstream protein produces radiosensitization.

METHODS/RESULTS

A431 cells (human squamous cell carcinoma cells with EGFr overexpression) were found to be sensitized to radiation after treatment with STAT-3 small interfering RNA (siRNA). Therefore, a short hairpin RNA (shRNA) against STAT-3 was designed and cloned into a pBABE vector system modified for shRNA expression. Following transfection, clone 2.1 was selected for further study as it showed a dramatic reduction of STAT-3 protein (and mRNA) when compared to A431 parental cells or a negative control shRNA cell line (transfected with STAT-3 shRNA with 2 base pairs mutated). A431 2.1 showed doubling times of 25-31h as compared to 18-24h for the parental cell line. The A431 shRNA knockdown STAT-3 cells A431 were more sensitive to radiation than A431 parental or negative STAT-3 control cells.

CONCLUSION

A431 cells stably transfected with shRNA against STAT-3 resulted in enhanced radiosensitivity. Further work will be necessary to determine whether the inhibition of STAT-3 phosphorylation is a necessary step for the radiosensitization that is induced by the inhibition of EGFr.

Mirk/Dyrk1B, a novel therapeutic target, mediates cell survival in non-small cell lung cancer cells

Minibrain-related kinase (Mirk) is a member of the dual specificity tyrosine-phosphorylation-regulated kinase (Dyrk)/minibrain family of dual-specificity protein kinases and is identical to Dyrk1B. Mirk/Dyrk1B is a serine/threonine kinase that has been found to be upregulated in solid tumors and mediates cell survival in colon cancer, pancreatic ductal adenocarcinoma and rhabdomyosarcomas. There is little known about Mirk in lung cancer. In the present study, we showed that Mirk protein was widely overexpressed in 13 of 19 NSCLC cell lines. Mirk immunoprecipitation coupled with anti-phosphotyrosine western blotting confirmed tyrosine phosphorylation of Mirk in NSCLC cells. Mirk knockdown by small interfering RNA induced cell apoptosis concomitant with upregulation of Bak, a Bcl-2 family member, and downregulation of signal transducers and activators of transcription 3 (STAT3) tyrosine phosphorylation. Mirk knockdown led to decreased cell colony formation in vitro as well as delayed tumor growth in an orthotopic mouse model and sensitized cells to cisplatin-induced apoptosis. Using automated quantitative determination of the Mirk protein in tumor specimens of patients with early-stage lung cancer, overexpression of Mirk was found in nearly 90% of tumor specimens in both the cytoplasm and nucleus. These results suggest that Mirk is overexpressed in lung cancer, acts as a survival factor in lung cancer cells and may be a novel therapeutic target.

Inflammation and cancer: how friendly is the relationship for cancer patients?

Evidence has emerged in the last two decades that at the molecular level most chronic diseases, including cancer, are caused by a dysregulated inflammatory response. The identification of transcription factors such as NF-kappaB, AP-1 and STAT3 and their gene products such as tumor necrosis factor, interleukin-1, interleukin-6, chemokines, cyclooxygenase-2, 5 lipooxygenase, matrix metalloproteases, and vascular endothelial growth factor, adhesion molecules and others have provided the molecular basis for the role of inflammation in cancer. These inflammatory pathways are activated by tobacco, stress, dietary agents, obesity, alcohol, infectious agents, irradiation, and environmental stimuli, which together account for as much as 95% of all cancers. These pathways have been implicated in transformation, survival, proliferation, invasion, angiogenesis, metastasis, chemoresistance, and radioresistance of cancer, so much so that survival and proliferation of most types of cancer stem cells themselves appear to be dependent on the activation of these inflammatory pathways. Most of this evidence, however, is from preclinical studies. Whether these pathways have any role in prevention, progression, diagnosis, prognosis, recurrence or treatment of cancer in patients, is the topic of discussion of this review. We present evidence that inhibitors of inflammatory biomarkers may have a role in both prevention and treatment of cancer.

Expression of the receptor tyrosine kinase EphA2 is increased in smokers and predicts poor survival in non-small cell lung cancer

PURPOSE

Up-regulation of the receptor tyrosine kinase EphA2 has been shown in several epithelial cancers. Epidermal growth factor receptor (EGFR) and K-Ras have been reported to regulate EphA2 in several in vitro models, but this regulation has never been examined in tumors from patients. Because of the established importance of EGFR and K-Ras mutations in non-small cell lung cancer (NSCLC), we investigated the relationship between these mutations and EphA2 in this cancer type. The significance of EphA2 expression was further examined by testing for correlation with other clinical parameters.

EXPERIMENTAL DESIGN

EphA2 expression was analyzed by immunohistochemistry in tissue microarray format using surgically resected NSCLC specimens (n = 279). EGFR and K-Ras mutation status was determined for most specimens. The correlation between EphA2 expression and EGFR or K-Ras mutation status was examined, along with several clinicopathologic variables of the tumors. The effects of increasing EGFR and K-Ras activity on EphA2 expression and activity were examined in two cell lines.

RESULTS

EphA2 expression was detected in >90% of tumor samples. Expression of EphA2 was positively correlated with activated EGFR but not with EGFR mutations. EphA2 expression was increased in patients harboring K-Ras mutations. EphA2 expression was positively correlated with a history of smoking, and high EphA2 scores predicted poorer progression-free and overall survivals.

CONCLUSIONS

EphA2 expression in NSCLC is associated with K-Ras mutations, EGFR activation, smoking history, and poor prognosis. EphA2 expression is up-regulated in the context of EGFR or K-Ras activation. The potential of EphA2 as a therapeutic target for NSCLC should be further investigated.

Tissue micro array analysis of ganglioside N-glycolyl GM3 expression and signal transducer and activator of transcription (STAT)-3 activation in relation to dendritic cell infiltration and microvessel density in non-small cell lung cancer

BACKGROUND

Tumor immune escape and angiogenesis contribute to tumor progression, and gangliosides and activation of signal transducer and activator of transcription (STAT)-3 are implicated in these processes. As both are considered as novel therapeutic targets, we assessed the possible association of ganglioside GM3 expression and STAT3 activation with suppression of dendritic cell (DC) activation and angiogenesis in non-small cell lung cancer (NSCLC).

METHODS

Immunohistochemistry was performed on a tissue array to determine N-glycolyl GM3 (GM3) and phosphorylated STAT3 (pSTAT3) expression in 176 primary NSCLC resections. Median values of GM3 and pSTAT3 expression were used as cut off. Microvessel density (MVD) was determined by CD34 staining and morphology. CD1a and CD83 were used to determine infiltrating immature and mature dendritic cells, respectively.

RESULTS

94% and 71% of the NSCLC samples expressed GM3 and nuclear pSTAT3, respectively. Median overall survival was 40.0 months. Both low GM3 expression and high pSTAT3 expression were associated with a worse survival, which reached near significance for GM3 (P = 0.08). Microvessel density (MVD), determined by CD34 staining and morphology, was lower in NSCLC samples with high GM3 expression. CD1a+ cells (immature DCs) were more frequent in NSCLC tissues as compared to peritumoral lung tissue, while CD83+ cells (mature DCs) were more frequent in peritumoral lung tissue. CD83+ DCs were less frequent in NSCLC tissues with high GM3 expression.

CONCLUSION

GM3 and pSTAT3 are widely expressed in NSCLC. Based on CD83 expression, GM3, but not pSTAT3, appeared to be involved in tumor-induced DC suppression. pSTAT3 expression was not associated with MVD, while GM3 might play an anti-angiogenic role.

The role of cooperativity with Src in oncogenic transformation mediated by non-small cell lung cancer-associated EGF receptor mutants

Non-small cell lung cancer (NSCLC)-associated epidermal growth factor receptor (EGFR) mutants are constitutively active and induce ligand-independent transformation in non-malignant cell lines. We investigated the possibility that the ability of mutant EGFRs to transform cells reflects a constitutive cooperativity with Src using a system in which the overexpression of mutant, but not wild-type, EGFR induced anchorage-independent cell growth. Src was constitutively activated and showed enhanced interaction with mutant EGFRs, suggesting that constitutive EGFR-Src cooperativity may contribute to mutant EGFR-mediated oncogenesis. Indeed, the mutant EGFR-mediated cell transformation was inhibited by Src- as well as EGFR-directed inhibitors. Importantly, a tyrosine to phenylalanine mutation of the major Src phosphorylation site on EGFR, Y845, reduced the constitutive phosphorylation of NSCLC-EGFR mutants, as well as that of STAT3, Akt, Erk and Src, and reduced the mutant EGFR-Src association as well as proliferation, migration and anchorage-independent growth. Reduced anchorage-independent growth and migration were also observed when dominant-negative-Src was expressed in mutant EGFR-expressing cells. Overall, our findings show that mutant EGFR-Src interaction and cooperativity play critical roles in constitutive engagement of the downstream signaling pathways that allow NSCLC-associated EGFR mutants to mediate oncogenesis, and support the rationale to target Src-dependent signaling pathways in mutant EGFR-mediated malignancies.

The role of cooperativity with Src in oncogenic transformation mediated by non-small cell lung cancer-associated EGF receptor mutants

Non-small cell lung cancer (NSCLC)-associated epidermal growth factor receptor (EGFR) mutants are constitutively active and induce ligand-independent transformation in non-malignant cell lines. We investigated the possibility that the ability of mutant EGFRs to transform cells reflects a constitutive cooperativity with Src using a system in which the overexpression of mutant, but not wild-type, EGFR induced anchorage-independent cell growth. Src was constitutively activated and showed enhanced interaction with mutant EGFRs, suggesting that constitutive EGFR-Src cooperativity may contribute to mutant EGFR-mediated oncogenesis. Indeed, the mutant EGFR-mediated cell transformation was inhibited by Src- as well as EGFR-directed inhibitors. Importantly, a tyrosine to phenylalanine mutation of the major Src phosphorylation site on EGFR, Y845, reduced the constitutive phosphorylation of NSCLC-EGFR mutants, as well as that of STAT3, Akt, Erk and Src, and reduced the mutant EGFR-Src association as well as proliferation, migration and anchorage-independent growth. Reduced anchorage-independent growth and migration were also observed when dominant-negative-Src was expressed in mutant EGFR-expressing cells. Overall, our findings show that mutant EGFR-Src interaction and cooperativity play critical roles in constitutive engagement of the downstream signaling pathways that allow NSCLC-associated EGFR mutants to mediate oncogenesis, and support the rationale to target Src-dependent signaling pathways in mutant EGFR-mediated malignancies.

Stat3 downstream genes serve as biomarkers in human lung carcinomas and chronic obstructive pulmonary disease

Smoking causes lung cancer and chronic obstructive pulmonary disease (COPD) that impose severe health problem to humans. Both diseases are related to each other and can be induced by chronic inflammation in the lung. To identify the molecular mechanism for lung cancer formation, a CCSP-rtTA/(teto)(7)Stat3C bitransgenic model was generated recently. In this model, persistent activation of the Stat3 signaling pathway induced pulmonary inflammation and adenocarcinoma formation in the lung. A group of Stat3 downstream genes were identified by Affymetrix GeneChip microarray analysis that can be used as biomarkers for lung cancer diagnosis and prognosis. To determine which human lung cancers are related to the Stat3 pathway, multiple Stat3 downstream genes were screened in human lung cancers (adenocarcinomas and squamous cell carcinomas) and lung tissue with COPD. In both cancer and COPD, the Stat3 gene was up-regulated. A panel of Stat3-up-regulated downstream genes in mice was up-regulated in human adenocarcinomas, but not in human squamous cell carcinomas. This panel of genes was also modestly up-regulated in lung tissue with COPD from patients with a history of smoking and not up-regulated in those without histories of smoking. Several Stat3-down-regulated downstream genes also showed differential expression patterns in carcinoma and COPD. These studies support a concept that Stat3 is a potent oncogenic molecule that plays a role in formation of lung adenocarcinomas in both mice and humans. The carcinogenesis of adenocarcinoma and squamous cell carcinoma is mediated by different molecular mechanisms and pathways in vivo. Stat3 and its downstream genes can serve as biomarkers for lung adenocarcinoma and COPD diagnosis and prognosis in mice and humans.

Rational use of cetuximab in the treatment of advanced non-small cell lung cancer

Lung cancer is the leading cause of mortality in the United States. Non-small cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancers. Most NSCLC patients present with loco-regionally advanced or metastatic disease where response rates are low and median overall survival approximates 8 to 10 months. Chemotherapy is the mainstay of treatment for NSCLC patients with metastatic disease. Epidermal growth factor receptor (EGFR) and family of receptors play a critical role in lung cancer tumorigenesis. Cetuximab, a monoclonal antibody that binds the EGFR, has demonstrated preclinical and clinical activity against NSCLC. This review focuses on the use of cetuximab in NSCLC.

Combined assessment of EGFR pathway-related molecular markers and prognosis of NSCLC patients

The purpose of this study is to evaluate the prognostic value of the combined assessment of multiple molecular markers related to the epidermal growth factor receptor (EGFR) pathway in resected non-small cell lung cancer (NSCLC) patients. Tumour specimens of 178 NSCLC patients were collected and analysed for EGFR and KRAS mutation status by DNA sequencing, and for EGFR copy number by fluorescent in situ hybridisation. Tissue microarrays were generated and used to determine the expression of multiple EGFR pathway-related proteins by immunohistochemistry. We analysed the association between each marker and patient prognosis. Univariate analyses for each clinical variable and each molecular marker were performed using Kaplan-Meier curves and log-rank tests. From these results, we selected the variables KRAS mutations and expression of cytoplasmic EGFR, granular pERK, nuclear pSTAT3, cytoplasmic E-cadherin and cytoplasmic pCMET to enter into a Cox proportional hazards model, along with stage as the strongest clinical variable related with prognosis. Of the EGFR-related markers evaluated here, the markers EGFR, pERK, pSTAT3, E-cadherin, pCMET and mutations in KRAS were associated with survival when analysed in combination in our patient cohort, with P=0.00015 as the P-value for a test of the additional impact of markers on prognosis, after taking stage into consideration. Confirmation of the impact of these markers in independent studies will be necessary.