Silencing of the type 1 insulin-like growth factor receptor increases the sensitivity to apoptosis and inhibits invasion in human lung adenocarcinoma A549 cells

Protein interaction networks characterizing the A549 cells Klotho transfected are associated with activated pro-apoptotic Bim and suppressed Wnt/β-catenin signaling pathway

Invasive assays and lung tumor-bearing mice models using a human lung adenocarcinoma cell line A549 cells transfected with the Klotho (KL) gene, A549/KL cells, have confirmed that KL suppresses invasive/metastatic potential. This study aimed to identify the co-expression protein networks and proteomic profiles associated with A549/KL cells to understand how Klotho protein expression affects molecular networks associated with lung carcinoma malignancy. A two-step application of a weighted network correlation analysis to the cells' quantitative proteome datasets of a total of 6,994 proteins, identified by mass spectrometry-based proteomic analysis with data-independent acquisition (DIA), identified one network module as most significantly associated with the A549/KL trait. Upstream analyses, confirmed by western blot, implicated the pro-apoptotic Bim (Bcl-2-like protein 11) as a master regulator of molecular networks affected by Klotho. GeneMANIA interaction networks and quantitative proteome data implicated that Klotho interacts with two signaling axes: negatively with the Wnt/β-catenin axis, and positively by activating Bim. Our findings might contribute to the development of future therapeutic strategies.

The novel hsa-miR-12528 regulates tumourigenesis and metastasis through hypo-phosphorylation of AKT cascade by targeting IGF-1R in human lung cancer

Lung cancer cases are increasing yearly; however, few novel therapeutic strategies for treating this disease have been developed. Here the dysregulation between microRNAs and oncogenes or tumour-suppressor genes forms a close connection-loop to the development or progression in human lung carcinogenesis. That is, the relationship between microRNAs and carcinogenic mechanism may find the critical clue to improve the treatment efficacy. Accordingly, we identified and characterised a novel microRNA, hsa-miR-12528, in A549 cells. The miR-12528 expression was aberrantly downregulated in cancer cell lines and in the patient tissues derived from human non-small cell lung cancer. In addition, we found that miR-12528 post-transcriptionally controls the translation of the insulin-like growth factor 1 receptor (IGF-1R) gene by directly targeting the 3′-untranslated region of IGF-1R mRNA. Notably, the IGF-1R gene is elevated in the majority of cancers and may be an attractive therapeutic target for anticancer therapy because elevated IGF-1R mediates the signalling amplification of a major oncogenic pathway in neoplasia. In A549 cells, miR-12528 overexpression epigenetically altered the downstream phosphorylation of the primary IGF-1R networks, negatively regulated proliferation, apoptosis and migratory activity, and consequently inhibited tumourigenesis and metastasis in vivo. Therefore, our discovery of hsa-miR-12528 may be able to be applied to the development of molecular-target therapeutic strategies and diagnosis-specific biomarkers for human lung cancer.

BMS-754807 is cytotoxic to non-small cell lung cancer cells and enhances the effects of platinum chemotherapeutics in the human lung cancer cell line A549

Background

Despite advances in targeted therapy for lung cancer, survival for patients remains poor and lung cancer remains the leading cause of cancer-related deaths worldwide. The type I insulin-like growth factor receptor (IGF-IR) has emerged as a potential target for lung cancer treatment, however, clinical trials to date have provided disappointing results. Further research is needed to identify if certain patients would benefit from IGF-IR targeted therapies and the ideal approach to incorporate IGF-IR targeted agents with current therapies.

Methods

The dual IGF-IR/insulin receptor inhibitor, BMS-754807, was evaluated alone and in combination with platinum-based chemotherapeutics in two human non-small cell lung cancer (NSCLC) cell lines. Cell survival was determined using WST-1 assays and drug interaction was evaluated using Calcusyn software. Proliferation and apoptosis were determined using immunofluorescence for phospho-histone H3 and cleaved caspase 3, respectively.

Results

Treatment with BMS-754807 alone reduced cell survival and wound closure while enhancing apoptosis in both human lung cancer cell lines. These effects appear to be mediated through IGF-IR/IR signaling and, at least in part, through the PI3K/AKT pathway as administration of BMS-754807 to A549 or NCI-H358 cells significantly suppressed IGF-IR/IR and AKT phosphorylation. In addition of BMS-754807 enhanced the cytotoxic effects of carboplatin or cisplatin in a synergistic manner when given simultaneously to A549 cells.

Conclusions

BMS-754807 may be an effective therapeutic agent for the treatment of NSCLC, particularly in lung cancer cells expressing high levels of IGF-IR.

Tissue distribution and cancer growth inhibition of magnetic lipoplex-delivered type 1 insulin-like growth factor receptor shRNA in nude mice

The targeted delivery of therapeutic genes into specific tissues, as well as the determination of the biological fate and potential toxicity of nanoparticles, remains a highly relevant challenge for gene-based therapies. Type 1 insulin-like growth factor receptor (IGF-1R), an important oncogene, is frequently over-expressed in lung cancer and mediates cancer cell proliferation as well as tumor growth. In our previous studies, we have successfully applied gene delivery mediated by commercially available nanoparticles (CombiMAG) under a magnetic field, which suppresses IGF-1R expression in a non-small cell lung cancer cell line (A549) in vitro. In the present study, we aimed to investigate the biological distribution and target tumor suppression of magnetofection, as well as its potential toxicity via CombiMAG-carrying plasmids expressing green fluorescent protein (GFP) and short hairpin RNAs (shRNAs) targeting IGF-1R (pGFPshIGF-1Rs) in tumor-bearing mice. The peak expression in various organs appeared 48 h after transfection. Transgene expression via magnetofection was 3-fold improvement than via lipofection. On the 30th day after injection, the tumor size and weight of the CombiMAG-treated group (789.32 ± 39.43 mm(3), 105.5 ± 6.1 mg) were significantly decreased compared with those of the lipofection group (893.83 ± 31.23 mm(3), 164.5 ± 9.1 mg; P< 0.05), and the suppression rate was ∼36%. After a 30-day observation, the injection of CombiMAG did not cause any apparent toxicity. Therefore, IGF-1R shRNA nanoparticles can be valuable and safe delivery agents for RNA interference therapy to tumors in vivo.

TROP2 is epigenetically inactivated and modulates IGF-1R signalling in lung adenocarcinoma

Trop-2, a cell surface glycoprotein, contains both extracellular epidermal growth factor-like and thyroglobulin type-1 repeat domains. Low TROP2 expression was observed in lung adenocarcinoma tissues as compared with their normal counterparts. The lack of expression could be due to either the loss of heterozygosity (LOH) or hypermethylation of the CpG island DNA of TROP2 upstream promoter region as confirmed by bisulphite sequencing and methylation-specific (MS) polymerase chain reaction (PCR). 5-Aza-2′-deoxycytidine treatment on lung cancer cell (CL) lines, CL1-5 and A549, reversed the hypermethylation status and elevated both TROP2 mRNA and protein expression levels. Enforced expression of TROP2 in the lung CL line H1299 reduced AKT as well as ERK activation and suppressed cell proliferation and colony formation. Conversely, silencing TROP2 with shRNA transfection in the less efficiently tumour-forming cell line H322M enhanced AKT activation and increased tumour growth. Trop-2 could attenuate IGF-1R signalling-mediated AKT/β-catenin and ERK activation through a direct binding of IGF1. In conclusion, inactivation of TROP2 due to LOH or by DNA methylation may play an important role in lung cancer tumourigenicity through losing its suppressive effect on IGF-1R signalling and tumour growth.

Dual targeting of the insulin-like growth factor and collateral pathways in cancer: combating drug resistance

The insulin-like growth factor pathway, regulated by a complex interplay of growth factors, cognate receptors, and binding proteins, is critically important for many of the hallmarks of cancer such as oncogenesis, cell division, growth, and antineoplastic resistance. Naturally, a number of clinical trials have sought to directly abrogate insulin-like growth factor receptor 1 (IGF-1R) function and/or indirectly mitigate its downstream mediators such as mTOR, PI3K, MAPK, and others under the assumption that such therapeutic interventions would provide clinical benefit, demonstrable by impaired tumor growth as well as prolonged progression-free and overall survival for patients. Though a small subset of patients enrolled within phase I or II clinical trials revealed dramatic clinical response to IGF-1R targeted therapies (most using monoclonal antibodies to IGF-1R), in toto, the anticancer effect has been underwhelming and unsustained, as even those with marked clinical responses seem to rapidly acquire resistance to IGF-1R targeted agents when used alone through yet to be identified mechanisms. As the IGF-1R receptor is just one of many that converge upon common intracellular signaling cascades, it is likely that effective IGF-1R targeting must occur in parallel with blockade of redundant signaling paths. Herein, we present the rationale for dual targeting of IGF-1R and other signaling molecules as an effective strategy to combat acquired drug resistance by carcinomas and sarcomas.

IGF1R signaling in Ewing sarcoma is shaped by clathrin-/caveolin-dependent endocytosis

Receptor endocytosis is critical for cell signaling. IGF1R mediates an autocrine loop that is de-regulated in Ewing Sarcoma (ES) cells. Here we study the impact of IGF1R internalization, mediated by clathrin and caveolin-1 (CAV1), in ES signaling. We used clathrin and CAV1-siRNA to interfere in clathrin- and caveolin-dependent endocytosis. Chlorpromazine (CPMZ) and methyl-beta-cyclo-dextrin (MCD) were also used in order to inhibit clathrin- and caveolin-dependent endocytosis, respectively. We analyzed IGF1R internalization and co-localization with clathrin and CAV1 upon ligand binding, as well as the status of the IGF1R pathway, cellular proliferation, and the apoptosis of interfered and inhibited ES cells. We performed a high-throughput tyrosine kinase phosphorylation assay to analyze the effects of combining the IGF1R tyrosine kinase inhibitor AEW541 (AEW) with CPMZ or MCD on the intracellular phospho-proteome. We observed that IGF1R is internalized upon ligand binding in ES cells and that this process is dependent on clathrin or CAV1. The blockage of receptor internalization inhibited AKT and MAPK phosphorylation, reducing the proliferative rate of ES cells and increasing the levels of apoptosis. Combination of AEW with CPMZ or MCD largely enhanced these effects. CAV1 and clathrin endocytosis controls IGF1R internalization and signaling and has a profound impact on ES IGF1R-promoted survival signaling. We propose the combination of tyrosine-kinase inhibitors with endocytosis inhibitors as a new therapeutic approach to achieve a stronger degree of receptor inhibition in this, or other neoplasms dependent on IGF1R signaling.

Klotho inhibits growth and promotes apoptosis in human lung cancer cell line A549

Background

Klotho, as a new anti-aging gene, can shed into circulation and act as a multi-functional humoral factor that influences multiple biological processes. Recently, published studies suggest that klotho can also serve as a potential tumor suppressor. The aim of this study is to investigate the effects and possible mechanisms of action of klotho in human lung cancer cell line A549.

Methods

In this study, plasmids encoding klotho or klotho specific shRNAs were constructed to overexpress or knockdown klotho in vitro. A549 cells were respectively treated with pCMV6-MYC-KL or klotho specific shRNAs. The MTT assay was used to evaluate the cytotoxic effects of klotho and flow cytometry was utilized to observe and detect the apoptosis of A549 cells induced by klotho. The activation of IGF-1/insulin signal pathways in A549 cells treated by pCMV6-MYC-KL or shRNAs were evaluated by western blotting. The expression levels of bcl-2 and bax transcripts were evaluated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

Results

Overexpression of klotho reduced the proliferation of lung cancer A549 cells, whereas klotho silencing in A549 cells enhanced proliferation. Klotho did not show any effects on HEK-293 cells. Klotho overexpression in A549 cells was associated with reduced IGF-1/insulin-induced phosphorylation of IGF-1R (IGF-1 receptor)/IR (insulin receptor) (P < 0.01). Overexpression of klotho can promote the apoptosis of A549 cells (P < 0.01). Overexpression of klotho, a bcl family gene bax, was found up-regulated and bcl-2, an anti-apoptosis gene, was found down-regulated (P < 0.01). In contrast, bax and bcl-2 were found down-regulated (P < 0.05) and up-regulated (P < 0.01), respectively when silencing klotho using shRNAs.

Conclusions

Klotho can inhibit proliferation and increase apoptosis of A549 cells, this may be partly due to the inhibition of IGF-1/insulin pathways and involving regulating the expression of the apoptosis-related genes bax/bcl-2. Thus, klotho can serve as a potential tumor suppressor in A549 cells.

The IGF-I receptor can alter the matrix metalloproteinase repertoire of tumor cells through transcriptional regulation of PKC-{alpha}

The IGF-I receptor (IGF-IR) was identified as a tumor progression factor, but its role in invasion and metastasis has been the subject of some controversy. Previously we reported that in murine lung carcinoma M-27 cells, overexpression of IGF-IR increased the synthesis and activation of matrix metalloproteinase (MMP)-2 via Akt/phosphatidylinositol 3-kinase signaling. In contrast, we show here that in these and other cells, IGF-IR overexpression reduced the constitutive and phorbol 12-myristate 13-acetate (PMA)-inducible expression of three protein kinase C (PKC)-regulated metalloproteinases, MMP-3, MMP-9, and MMP-13, in cultured cells as well as in vivo in sc tumors. To elucidate the underlying mechanism, we analyzed the effect of IGF-IR on PKC expression and activity using wild-type and IGF-IR-overexpressing (M-27(IGFIR)) tumor cells. Our results show that overexpression and activation of IGF-IR reduced PKC-alpha expression, PKC activity, and downstream ERK1/2 signaling, and these effects were reversed in cells expressing kinase (Y(1131,1135,1136)F) or C-terminal (Y(1250/51)F) domain mutants of IGF-IR. This reduction was due to transcriptional down-regulation of PKC-alpha as evidenced by reduced PKC-alpha mRNA expression in a phosphatidylinositol 3-kinase-dependent manner and a blockade of PKC-alpha promoter activation as revealed by a reporter gene assay. Finally, reconstitution of PKC-alpha levels could restore MMP-9 expression levels in these cells. Collectively, these results show that IGF-IR can inhibit PKC-alpha gene transcription and thereby block the synthesis of PMA-regulated MMPs, suggesting that within the same cells, IGF-IR can act as both a positive and negative regulator of MMP expression and function.

Lentivirus-mediated RNAi knockdown of insulin-like growth factor-1 receptor inhibits growth, reduces invasion, and enhances radiosensitivity in human osteosarcoma cells

The type 1 insulin-like growth factor receptor (IGF-1R) is essential for tumorigenicity, tumor proliferation, and protection from apoptosis. IGF-1R overexpression has been found in many human cancers including osteosarcoma. To explore its possibility as a therapeutic target for the treatment of osteosarcoma, lentivirus-mediated siRNA was employed to downregulate endogenous IGF-1R expression to study the function of IGF-1R in tumorigenesis and radioresistance of osteosarcoma cells. The IGF-1R expression was persistently and markedly reduced by lentivirus-mediated RNAi. Downregulation of IGF-1R expression in osteosarcoma cells significantly suppressed their growth rates in vitro and reduced the potential of tumorigenicity in vivo. Moreover, the specific downregulation arrested cells in G(0)/G(1) phase of cell cycle and also induced apoptosis which correlated with the activation of Caspase-3. Furthermore, we also observed that suppression of IGF-1R could reduce the invasiveness of osteosarcoma cells and enhance their radiosensitivity. Our study suggested that lentivirus-mediated RNAi silencing targeting IGF-1R could induce potent antitumor activity and radiosensitizing activity in human osteosarcomas.

Insulin-like growth factor-1 receptor-targeted therapy for non-small cell lung cancer: a mini review

Lung cancer leads all other cancers in both incidence and mortality. Recent advances in underlying molecular pathogenesis have validated a panel of protein tyrosine kinases as new targets in lung cancer treatment. Insulin-like growth factor-1 receptor (IGF-1R) is an important tyrosine kinase receptor involved in cell proliferation, differentiation, metabolism, apoptosis, and angiogenesis. Aberrant activation of IGF-1R is frequently found in patients with lung cancer and contributes to malignant transformation and poor prognosis for patients with lung cancer. In this review, we focused on recent progress in the research of IGF-1R's role in lung cancer development and progression, including its structure and biological function, potential mechanisms of aberrant activation, and related oncogenic effects. We also discussed effective IGF-1R antagonists that are currently registered for clinic trials or are undergoing preclinical study with special emphasis on their antibodies and small molecule tyrosine kinase inhibitors.

Personalized therapy of sarcomas: integration of biomarkers for improved diagnosis, prognosis, and therapy selection

An improved understanding of cancer's molecular diversity at the genetic, proteomic, and epigenetic levels has made it evident that "sarcoma" comprises more than 50 different types, each as unique as, for example, breast carcinoma is from colon carcinoma. Sarcomas exhibit characteristic differences in cell of origin, disease site, likelihood and site of metastasis, growth propensity, and chemosensitivity. Additionally, as many as one third of sarcomas harbor specific chromosomal translocations that can be used to discriminate one subtype from another. Although biomarkers can be integrated into clinical practice to improve diagnostic accuracy and predict treatment response, a number of challenges hinder their widespread use. This review addresses the current use of biomarkers for clinical oncology, with special emphasis on diagnosis, staging, and grading. It also discusses types of biomarkers that are emerging to aid selection of therapy for patients with sarcoma. Finally, we consider practical factors that appear to limit biomarker integration into clinical practice.

Activated c-Abl tyrosine kinase in malignant solid tumors

Mutant forms of the c-ABL gene are well known to be involved in hematopoietic malignancies such as chronic myeloid leukemia (CML). CML patients possess a fused BCR-ABL gene that activates the Abl tyrosine kinase domain within Bcr-Abl. In general fusion proteins that cause oligomerization of Abl lead to activation of its tyrosine kinase activity. In this review, we highlight recent discoveries indicating that the activated c-Abl tyrosine kinase, not as a fusion protein, plays an important role in malignant solid tumors of lung and breast.

Differential localization of MT1-MMP in human prostate cancer tissue: role of IGF-1R in MT1-MMP expression

BACKGROUND

MT1-MMP is a metalloproteinase involved in prostate cancer metastasis. The IGF-1R is a tyrosine kinase receptor involved with tumor progression and metastasis. The purpose of this investigation was to examine MT1-MMP and IGF-1R expression and localization in prostate cancer tissues and explore the role of IGF-1R in regulating MT1-MMP in prostate cancer cell lines.

METHODS

Immunohistochemistry was utilized to study MT1-MMP and IGF-1R expression in human prostate tissues. IGF-1R regulation of MT1-MMP expression was determined by gene promoter analysis, quantitative RT-PCR and Western blot analysis following pharmacological inhibition of the receptor in PC-3N cells and treatment of LNCaP cells with androgen and IGF-1.

RESULTS

MT1-MMP expression was high in the apical regions of the luminal cells in PIN and prostate cancer and less intense in the basalateral regions of benign tissues. IGF-1R was expressed primarily in the basal cells of normal glands and highly expressed in prostate cancer. Inhibition of IGF-1R in PC-3N cells decreased MT1-MMP expression and treatment of LNCaP cells with a synthetic androgen and IGF-1 increased MT1-MMP expression.

CONCLUSIONS

These data demonstrate that MT1-MMP is highly expressed in the apical cytoplasmic regions of the luminal cells in PIN and prostate cancer when compared to basalateral cytoplasmic membrane staining in benign glands. Additionally, we demonstrate that IGF-1R is highly expressed in human prostate carcinoma. These findings suggest that MT1-MMP localization and IGF-1R expression in prostate carcinoma could be predictive biomarkers for aggressive disease and support IGF-1R as a promising therapeutic target to decrease processes of prostate cancer metastasis.