Adenovirus expressing shRNA to IGF-1R enhances the chemosensitivity of lung cancer cell lines by blocking IGF-1 pathway

Role of Insulin-like Growth Factor-1 Receptor in Tobacco Smoking-Associated Lung Cancer Development

Cancer remains a significant global health concern, with lung cancer consistently leading as one of the most common malignancies. Genetic aberrations involving receptor tyrosine kinases (RTKs) are known to be associated with cancer initiation and development, but RTK involvement in smoking-associated lung cancer cases is not well understood. The Insulin-like Growth Factor 1 Receptor (IGF-1R) is a receptor that plays a critical role in lung cancer development. Its signaling pathway affects the growth and survival of cancer cells, and high expression is linked to poor prognosis and resistance to treatment. Several reports have shown that by activating IGF-1R, tobacco smoke-related carcinogens promote lung cancer and chemotherapy resistance. However, the relationship between IGF-1R and cancer is complex and can vary depending on the type of cancer. Ongoing investigations are focused on developing therapeutic strategies to target IGF-1R and overcome chemotherapy resistance. Overall, this review explores the intricate connections between tobacco smoke-specific carcinogens and the IGF-1R pathway in lung carcinogenesis. This review further highlights the challenges in using IGF-1R inhibitors as targeted therapy for lung cancer due to structural similarities with insulin receptors. Overcoming these obstacles may require a comprehensive approach combining IGF-1R inhibition with other selective agents for successful cancer treatment.

Crizotinib-induced antitumour activity in human alveolar rhabdomyosarcoma cells is not solely dependent on ALK and MET inhibition

Background

Rhabdomyosarcoma (RMS) is the most commonly diagnosed malignant soft tissue tumour in children and adolescents. Aberrant expression of Anaplastic Lymphoma Kinase (ALK) and MET gene has been implicated in the malignant progression of RMS, especially in the alveolar subtype. This observation suggests that crizotinib (PF-02341066), a kinase inhibitor against ALK and MET, may have a therapeutic role in RMS, although its antitumour activity in this malignancy has not yet been studied.

Methods

RH4 and RH30 alveolar RMS (ARMS) cell lines were treated with crizotinib and then assessed by using proliferation, viability, migration and colony formation assays. Multiple approaches, including flow cytometry, immunofluorescence, western blotting and siRNA-based knock-down, were used in order to investigate possible molecular mechanisms linked to crizotinib activity.

Results

In vitro treatment with crizotinib inhibited ALK and MET proteins, as well as Insulin-like Growth Factor 1 Receptor (IGF1R), with a concomitant robust dephosphorylation of AKT and ERK, two downstream kinases involved in RMS cell proliferation and survival. Exposure to crizotinib impaired cell growth, and accumulation at G2/M phase was attributed to an altered expression and activation of checkpoint regulators, such as Cyclin B1 and Cdc2. Crizotinib was able to induce apoptosis and autophagy in a dose-dependent manner, as shown by caspase-3 activation/PARP proteolytic cleavage down-regulation and by LC3 activation/p62 down-regulation, respectively. The accumulation of reactive oxygen species (ROS) seemed to contribute to crizotinib effects in RH4 and RH30 cells. Moreover, crizotinib-treated RH4 and RH30 cells exhibited a decreased migratory/invasive capacity and clonogenic potential.

Conclusions

These results provide a further insight into the molecular mechanisms affected by crizotinib in ARMS cells inferring that it could be a useful therapeutic tool in ARMS cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0228-4) contains supplementary material, which is available to authorized users.

Obesity and resistance to cancer chemotherapy: interacting roles of inflammation and metabolic dysregulation

The prevalence of obesity, an established risk factor for many chronic diseases, including several types of cancer, has risen steadily over the past four decades in the United States and worldwide. To date, research in this area has focused on the epidemiologic associations between obesity and cancer risk, as well as on the mechanisms underlying those associations. However, an emerging but understudied issue of clinical importance is the diminution of chemotherapeutic efficacy in obese cancer patients. The mechanisms underlying the negative impact of obesity on therapeutic responses are likely multifactorial. The effects of obesity on chemotherapy drug pharmacokinetics and dosage have been extensively reviewed elsewhere, so this review will focus on the interplay among obesity, increased inflammation, metabolic perturbations, and chemoresistance. The ultimate goal of this review is to delineate areas for future research that could lead to the identification of new targets and strategies for improved cancer outcomes in obese patients.

The effect of IGF-I receptor blockade for human esophageal squamous cell carcinoma and adenocarcinoma

Insulin-like growth factor-I receptor (IGF-IR) signaling is required for carcinogenicity and tumor development, and this pathway has not been well studied in human esophageal carcinomas. Esophageal cancer is one of the human cancers with the worst prognosis and has two main histologies: squamous cell carcinomas (ESCC) and adenocarcinoma (EAC). Previously, we have reported that detection of the IGF axis may be useful for the prediction of recurrence and poor prognosis of ESCC. We have also shown the successful therapy for several gastrointestinal cancers using recombinant adenoviruses expressing dominant negative IGF-IR (ad-IGF-IR/dn). The aim of this study is to develop potential targeted therapeutics to IGF-IR and to assess the effect of IGF-IR blockade in both of these types of esophageal cancer. We determined immunohistochemical expression of IGF-IR in a tissue microarray. We then assessed the effect of IGF-IR blockade on signal transduction, proliferation, apoptosis, and motility. Ad-IGF-IR/dn, a tyrosine kinase inhibitor, BMS-536924, and adenovirus expressing shRNA for IGF-IR were used. IGF-IR expression was common in both tumor types but not in normal tissues. IGF-IR was detected in metastatic sites at similar levels compared to the primary site. IGF-IR inhibition suppressed proliferation and colony formation in both cancers. IGF-IR blockades up-regulated both stress- and chemotherapy-induced apoptosis and reduced migration. Although IGF-IR/dn blocked ligand-induced activation of Akt-1 mainly, BMS-536924 effectively blocked both activation of Akt and MAPK. The IGF axis might play a key role in tumor progression of esophageal carcinomas. The IGF-IR targeting strategies might thus be useful anticancer therapeutics for human esophageal malignancies.

The insulin-like growth factor system in cancer

Insulin-like growth factor (IGF) plays an important role in tissue growth and development. Several studies have demonstrated the association between circulating levels of IGF-1 and -2 and cancer risk, and the IGF system has been implicated in the oncogenesis of essentially all solid and hematologic malignancies. The optimal strategy for targeting IGF signaling in patients with cancer is not clear. The modest benefits reported thus far underscore the need for a better understanding of IGF signaling, which would enable clinicians to identify the subset of patients with the greatest likelihood of attaining benefit from this targeted approach.

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.

Insulin-like growth factor-type 1 receptor inhibitor NVP-AEW541 enhances radiosensitivity of PTEN wild-type but not PTEN-deficient human prostate cancer cells

PURPOSE

During the past decade, many clinical trials with both monoclonal antibodies and small molecules that target the insulin-like growth factor-type 1 receptor (IGF-1R) have been launched. Despite the important role of IGF-1R signaling in radioresistance, studies of such agents in combination with radiotherapy are lagging behind. Therefore, the aim of this study was to investigate the effect of the small molecule IGF-1R kinase inhibitor NVP-AEW541 on the intrinsic radioresistance of prostate cancer cells.

METHODS AND MATERIALS

The effect of NVP-AEW541 on cell proliferation, cell viability, IGF-1R signaling, radiosensitivity, cell cycle distribution, and double strand break repair was determined in three human prostate cancer cell lines (PC3, DU145, 22Rv1). Moreover, the importance of the PTEN pathway status was explored by means of transfection experiments with constitutively active Akt or inactive kinase-dead Akt.

RESULTS

NVP-AEW541 inhibited cell proliferation and decreased cell viability in a time-and dose-dependent manner in all three cell lines. Radiosensitization was observed in the PTEN wild-type cell lines DU145 and 22Rv1 but not in the PTEN-deficient PC3 cell line. NVP-AEW541-induced radiosensitization coincided with downregulation of phospho-Akt levels and high levels of residual double strand breaks. The importance of PTEN status in the radiosensitization effect was confirmed by transfection experiments with constitutively active Akt or inactive kinase-dead Akt.

CONCLUSIONS

NVP-AEW541 enhances the effect of ionizing radiation in PTEN wild-type, but not in PTEN-deficient, prostate cancer cells. Proper patient selection based on the PTEN status of the tumor will be critical to the achievement of optimal results in clinical trials in which the combination of radiotherapy and this IGF-1R inhibitor is being explored.

Current management of small cell lung cancer

Confined to one side of the chest, limited stage small cell lung cancer is treated with a combination of chemotherapy and radiotherapy, yet has a long-term survival rate of only 15%. Extensive stage disease has initial response rates to chemotherapy exceeding 70%. However, the disease almost invariably progresses and becomes fatal. Many recent clinical trials have failed to show superiority of newer chemotherapeutics or targeted therapies compared with the standard chemotherapy backbone of platinum plus etoposide. Numerous promising targeted therapies and other agents are still in development.

A candidate targeting molecule of insulin-like growth factor-I receptor for gastrointestinal cancers

Advances in molecular research in cancer have brought new therapeutic strategies into clinical usage. One new group of targets is tyrosine kinase receptors, which can be treated by several strategies, including small molecule tyrosine kinase inhibitors (TKIs) and monoclonal antibodies (mAbs). Aberrant activation of growth factors/receptors and their signal pathways are required for malignant transformation and progression in gastrointestinal (GI) carcinomas. The concept of targeting specific carcinogenic receptors has been validated by successful clinical application of many new drugs. Type I insulin-like growth factor (IGF) receptor (IGF-IR) signaling potently stimulates tumor progression and cellular differentiation, and is a promising new molecular target in human malignancies. In this review, we focus on this promising therapeutic target, IGF-IR. The IGF/IGF-IR axis is an important modifier of tumor cell proliferation, survival, growth, and treatment sensitivity in many malignant diseases, including human GI cancers. Preclinical studies demonstrated that downregulation of IGF-IR signals reversed the neoplastic phenotype and sensitized cells to anticancer treatments. These results were mainly obtained through our strategy of adenoviruses expressing dominant negative IGF-IR (IGF-IR/dn) against gastrointestinal cancers, including esophagus, stomach, colon, and pancreas. We also summarize a variety of strategies to interrupt the IGFs/IGF-IR axis and their preclinical experiences. Several mAbs and TKIs targeting IGF-IR have entered clinical trials, and early results have suggested that these agents have generally acceptable safety profiles as single agents. We summarize the advantages and disadvantages of each strategy and discuss the merits/demerits of dual targeting of IGF-IR and other growth factor receptors, including Her2 and the insulin receptor, as well as other alternatives and possible drug combinations. Thus, IGF-IR might be a candidate for a molecular therapeutic target in human GI carcinomas.

Exciting new targets in lung cancer therapy: ALK, IGF-1R, HDAC, and Hh

The anaplastic lymphoma kinase (ALK) inhibitor crizotinib will become an integral addition to the treatment of patients with non-small cell lung cancer (NSCLC) harboring genetic ALK translocations. The insulin-like growth factor receptor (IGF-1R) monoclonal antibody figitumumab, while initially promising, appears to increase toxicity and death in combination with chemotherapy in the treatment of patients with NSCLC of squamous histology; therefore, clinical development of this class of agents will need to proceed with caution. The histone deacetylation (HDAC) inhibitor vorinostat did not demonstrate an improvement in overall survival (OS) compared with placebo in a large randomized trial, but other agents in this class may have greater selectivity and efficacy. Inhibitors of the hedgehog (Hh) signaling pathways have some early clinical promise in both NSCLC and small cell lung cancer (SCLC), and larger studies using these agents are eagerly anticipated.

Lentivirus-mediated shRNA targeting insulin-like growth factor-1 receptor (IGF-1R) enhances chemosensitivity of osteosarcoma cells in vitro and in vivo

The overexpression of the type 1 insulin-like growth factor receptor (IGF-1R) has been reported to be associated with malignant transformation, tumor development and chemo- or radioresistance of tumor cells. Previously, we have reported that inhibition of IGF-1R could reverse the radioresistance of human osteosarcoma cells. However, whether inhibition of IGF-1R could enhance chemosensitivity of ostesosarcoma cells is unclear. In this study, lentivirus-mediated shRNA was employed to downregulate endogenous IGF-1R expression to study the function of IGF-1R in chemoresistance of osteosarcoma cells. Results showed that lentivirus-mediated shRNA targeting IGF-1R combined with chemotherapy (CDDP or DTX) could lead to growth suppression of osteosarcoma cells not only in vitro but also in vivo. Moreover, inhibition of IGF-1R gene combined with chemotherapy also synergistically enhanced Caspase-3-mediated apoptosis of osteosarcoma cells. The synergistical enhancement of apoptosis might be associated with downregulation of Bcl-2 and upregulation of Bax in osteosarcoma cells induced by IGF-1R inhibition. Therefore, the overexpression of IGF-1R gene might play important roles in chemoresistance of osteosarcoma cells, and lentivirus-mediated RNAi targeting IGF-1R would be an attractive anti-cancer strategy to chemosensitization of osteosarcoma cell.

Sequence-specific targeting of IGF-I and IGF-IR genes by camptothecins

We and others have clearly demonstrated that a topoisomerase I (Top1) inhibitor, such as camptothecin (CPT), coupled to a triplex-forming oligonucleotide (TFO) through a suitable linker can be used to cause site-specific cleavage of the targeted DNA sequence in in vitro models. Here we evaluated whether these molecular tools induce sequence-specific DNA damage in a genome context. We targeted the insulin-like growth factor (IGF)-I axis and in particular promoter 1 of IGF-I and intron 2 of type 1 insulin-like growth factor receptor (IGF-IR) in cancer cells. The IGF axis molecules represent important targets for anticancer strategies, because of their central role in oncogenic maintenance and metastasis processes. We chemically attached 2 CPT derivatives to 2 TFOs. Both conjugates efficiently blocked gene expression in cells, reducing the quantity of mRNA transcribed by 70-80%, as measured by quantitative RT-PCR. We confirmed that the inhibitory mechanism of these TFO conjugates was mediated by Top1-induced cleavage through the use of RNA interference experiments and a camptothecin-resistant cell line. In addition, induction of phospho-H2AX foci supports the DNA-damaging activity of TFO-CPT conjugates at specific sites. The evaluated conjugates induce a specific DNA damage at the target gene mediated by Top1.

Targeting for insulin-like growth factor-I receptor with short hairpin RNA for human digestive/gastrointestinal cancers

BACKGROUND AND AIMS

Insulin-like growth factor (IGF)-I receptor (IGF-IR) signaling plays important parts in both the tumorigenicity and progression of digestive/gastrointestinal malignancies. In this study, we sought to test the effectiveness of a practical approach to blocking IGF-IR signaling using RNA interference delivered by recombinant adenoviruses.

METHODS

We constructed a recombinant adenovirus expressing short hairpin RNA targeting IGF-IR (shIGF-IR) and assessed its effect on signal transduction, proliferation, and survival in digestive/gastrointestinal cancer cell lines representing colorectal, gastric, and pancreatic adenocarcinoma, esophageal squamous cell carcinoma, and hepatoma. We analyzed the effects of shIGF-IR alone and with chemotherapy in vitro and in nude mouse xenografts, as well as on insulin signaling and hybrid receptor formation between IGF-IR and insulin receptor.

RESULTS

shIGF-IR blocked expression and autophosphorylation of IGF-IR and downstream signaling by the IGFs, but not by insulin. shIGF-IR suppressed proliferation and carcinogenicity in vitro and up-regulated apoptosis in a dose-dependent fashion. shIGF-IR augmented the effects of chemotherapy on in vitro growth and apoptosis induction. Moreover, the combination of shIGF-IR and chemotherapy was highly effective against tumors in mice. shIGF-IR reduced hybrid receptor formation without effect on expression of insulin receptor.

CONCLUSIONS

shIGF-IR may have therapeutic utility in human digestive/gastrointestinal cancers, both alone and in combination with chemotherapy.

Antitumor activity of GSK1904529A, a small-molecule inhibitor of the insulin-like growth factor-I receptor tyrosine kinase

PURPOSE

Dysregulation of the insulin-like growth factor-I receptor (IGF-IR) signaling pathway has been implicated in the development of many types of tumors, including prostate, colon, breast, pancreatic, ovarian, and sarcomas. Agents that inhibit IGF-IR activity may be useful in treatment of patients with various cancers.

EXPERIMENTAL DESIGN

Kinase assays were used to identify a selective small-molecule inhibitor of IGF-IR activity. The effects of this compound on IGF-IR signaling, cell proliferation, and the cell cycle were determined using a panel of cell lines. Antitumor activity was evaluated in human tumor xenografts growing in athymic mice. Inhibition of IGF-IR and the closely related insulin receptor (IR) was measured in vivo, and the effect on glucose metabolism was evaluated.

RESULTS

GSK1904529A selectively inhibits IGF-IR and IR with IC(50)s of 27 and 25 nmol/L, respectively. GSK1904529A blocks receptor autophosphorylation and downstream signaling, leading to cell cycle arrest. It inhibits the proliferation of cell lines derived from solid and hematologic malignancies, with multiple myeloma and Ewing's sarcoma cell lines being most sensitive. Oral administration of GSK1904529A decreases the growth of human tumor xenografts in mice, consistent with a reduction of IGF-IR phosphorylation in tumors. Despite the potent inhibitory activity of GSK1904529A on IR in vitro and in vivo, minimal effects on blood glucose levels are observed in animals at doses that show significant antitumor activity.

CONCLUSION

GSK1904529A is a promising candidate for therapeutic use in IGF-IR-dependent tumors.

Dual silencing of type 1 insulin-like growth factor and epidermal growth factor receptors to induce apoptosis of nasopharyngeal cancer cells

OBJECTIVE

The epidermal growth factor receptor (EGFR) and type 1 insulin-like growth factor receptor (type 1 IGF receptor or IGF1R) have played an important role in the growth and apoptosis of cancer. The RNA interference (RNAi) technique can suppress gene expression, but the effects of dual silencing of EGFR and type 1 IGF receptor have not been well understood.

METHODS

pU6-EGFR-shRNA-1, pU6-EGFR-shRNA-2, pU6-IGF1R-shRNA-1 and pU6-IGF-1R-shRNA-2 plasimd vectors were transfected to the nasopharyngeal cancer cells. Seven groups were selected for the study. The protein and downstream protein expression were assessed by Western blot. Apoptosis was determined via flow cytometry. Meanwhile, chemosensitivity of nasopharyngeal cancer cell lines transfeced to chemotherapeutic drugs were carried out by MTT.

RESULTS

In dual silencing of EGFR and IGF-1R, the protein expression much more was decreased than single silencing of EGFR or IGF-1R, but the cell apoptosis much more is increased than single silencing EGFR or IGF-1R. Dual silencing of EGFR and IGF-1R enhanced chemosensitivity to anticancer drugs, compared with single silencing of EGFR or IGF-1R.

CONCLUSION

Dual silencing of EGFR and IGF-1R are capable of suppressing EGFR and IGF-1R expression of the nasopharyngeal cancer cell and can promote apoptosis and increase the cell sensitivity of anticancer drug. The dual silencing of genes RNAi technique is significantly better than a single gene.

RNAi and gene therapy: a mutual attraction

The phylogenetically conserved cellular phenomenon of RNA interference (RNAi)-the sequence-specific post-transcriptional silencing of gene expression mediated by small double-stranded RNAs-holds substantial promise for basic research and for drug development. Particularly attractive from a medical standpoint is the juxtaposition of new RNAi methodology with established gene transfer strategies, especially viral vectors for efficient and tissue-specific RNAi delivery to patients. Here, we summarize the latest experimental and clinical advances in RNAi-based gene therapy approaches. We briefly portray emerging nonviral strategies for siRNA transfer, before comparing the three viral vectors currently predominantly developed as shRNA delivery vehicles, adenovirus, lentivirus, and adeno-associated virus (AAV). Moreover, we describe the most clinically relevant genetic, acquired or infectious targets being pursued for therapeutic purposes. Specifically, we assess the use of vector-mediated RNAi for treatment of viral processes, solid cancers, lymphoproliferative disorders, and neurodegenerative and ocular diseases. In addition, we highlight further emerging applications, including stem cell therapies and animal transgenesis, as well as discuss some of the potential pitfalls and limitations inherent to the individual approaches. While we predict that eventual schemes will be shaped by our increasing understanding of the complexities of human RNAi biology, as well as by progressive refinements of viral shuttle designs, the potential scientific and medical benefits from a successful marriage of RNAi and gene therapy seem enormous.