Pulmonary adenocarcinoma-targeted gene therapy by a cancer- and tissue-specific promoter system

Optimized thyroid transcription factor-1 core promoter-driven microRNA-7 expression effectively inhibits the growth of human non-small-cell lung cancer cells

Targeted gene therapy has become a promising approach for lung cancer treatment. In our previous work, we reported that the targeted expression of microRNA-7 (miR-7) operated by thyroid transcription factor-1 (TTF-1) promoter inhibited the growth of human lung cancer cells in vitro and in vivo; however, the intervention efficiency needed to be further improved. In this study, we identified the core promoter of TTF-1 (from -1299 bp to -871 bp) by 5' deletion assay and screened out the putative transcription factors nuclear factor-1 (NF-1) and activator protein-1 (AP-1). Further analysis revealed that the expression level of NF-1, but not AP-1, was positively connected with the activation of TTF-1 core promoter in human non-small-cell lung cancer (NSCLC) cells. Moreover, the silencing of NF-1 could reduce the expression level of miR-7 operated by TTF-1 core promoter. Of note, we optimized four distinct sequences to form additional NF-1-binding sites (TGGCA) in the sequence of TTF-1 core promoter (termed as ^optTTF-1 promoter), and verified the binding efficiency of NF-1 on the ^optTTF-1 promoter by electrophoretic mobility shift assay (EMSA). As expected, the ^optTTF-1 promoter could more effectively drive miR-7 expression and inhibit the growth of human NSCLC cells in vitro, accompanied by a reduced transduction of NADH dehydrogenase (ubiquinone) 1α subcomplex 4 (NDUFA4)/protein kinase B (Akt) pathway. Consistently, ^optTTF-1 promoter-driven miR-7 expression could also effectively abrogate the growth and metastasis of tumor cells in a murine xenograft model of human NSCLC. Finally, no significant changes were detected in the biological indicators or the histology of some important tissues and organs, including heart, liver, and spleen. On the whole, our study revealed that the optimized TTF-1 promoter could more effectively operate miR-7 to influence the growth of human NSCLC cells, providing a new basis for the development of microRNA-based targeting gene therapy against clinical lung cancer.

Recent advances in aerosol gene delivery systems using non-viral vectors for lung cancer therapy

INTRODUCTION

Lung cancer commonly occurs at a high incidence worldwide. Application of aerosol gene delivery systems using various kinds of vectors can improve the patient's quality of life by prolonging the survival rate.

AREAS COVERED

This review provides a recent update on aerosol gene delivery strategies using various kinds of vectors and gene-modification technologies. Peptide-mediated gene therapy achieves specific targeting of cells and highly improves efficacy. Promoter-operating expression and the CRISPR/Cas9 system are novel gene therapy strategies for effective lung cancer treatment. Furthermore, hybrid systems with a combination of vectors or drugs have been recently applied as new trends in gene therapy.

EXPERT OPINION

Although aerosol gene delivery has many advantages, physiological barriers in the lungs pose formidable challenges. Targeted gene delivery and gene-editing technology are promising strategies for lung cancer therapy. These strategies may allow the development of safety and high efficiency for clinical application. Recently, hybrid gene therapy combining novel and specific vectors has been developed as an advanced strategy. Although gene therapy for lung cancer is being actively researched, aerosol gene therapy strategies are currently lacking, and further studies on aerosol gene therapy are needed to treat lung cancer.

Development of an integrated CRISPRi targeting ΔNp63 for treatment of squamous cell carcinoma

TP63 encodes TAp63, which is functionally similar to the tumor suppressor TP53, and ΔNp63, which lacks the transcription-activating domain of TAp63 and appears potently oncogenic in squamous cell carcinomas (SCCs). In this study, we developed an integrated CRISPR interference (CRISPRi) system to selectively suppress ΔNp63 (CRISPRiΔNp63). We engineered this CRISPRi using tandemized guide RNA expression cassettes that targeted the 50 to 100 bp downstream of the transcription start site of ΔNp63 in combination with inactivated Cas9 linked to the transcription repression module Krüppel-associated box repressor domain. The plasmid vector harboring CRISPRiΔNp63 repressed ΔNp63 transcription in lung and esophageal SCC cells. Likewise, Ad-CRISPRiΔNp63, an all-in-one adenoviral vector containing the tandemized gRNAs and dCas9/KRAB expression cassette suppressed ΔNp63 expression in SCC cells. Ad-CRISPRiΔNp63 also effectively decreased cell proliferation and colony formation and induced apoptosis in lung and esophageal SCC cells in vitro and significantly inhibited tumor growth in a mouse lung SCC xenograft model in vivo. These results indicate that ΔNp63 suppression using CRISPRiΔNp63 may be an effective strategy for treating lung and esophageal SCC.

Surfactant Protein A and Napsin A in the Immunohistochemical Characterization of Canine Pulmonary Carcinomas: Comparison With Thyroid Transcription Factor-1

Thyroid transcription factor-1 (TTF-1) is a specific and sensitive marker for canine pulmonary tumors but is also expressed in thyroid carcinomas, which commonly metastasize to lung. Napsin A and surfactant protein A (SP-A) are used in the histologic diagnosis of non-small-cell lung cancer in humans but have not been thoroughly evaluated in neoplasms of dogs. The objective of this study was to compare the efficacy of immunohistochemistry for SP-A, napsin A, and TTF-1 in the diagnosis of canine pulmonary carcinomas. TTF-1, napsin A, and SP-A antibodies were applied to 67 formalin-fixed, paraffin-embedded canine pulmonary tumors. Although each marker had good sensitivity, only 3% (2/67) of lung tumors were negative for SP-A compared with 7% (5/67) and 9% (6/67) for napsin A and TTF-1, respectively. Each antigen was detected in a greater percentage of cells of tumors with acinar or papillary patterns compared with those with squamous differentiation. SP-A immunoreactivity was absent in all 113 nonpulmonary tumors tested. Of 108 normal tissues, SP-A was detected only in lung and in 1 of 6 adrenal, 1 of 3 endometrial, and 1 of 4 hepatic sections. Based on these findings, SP-A and napsin A are useful markers of canine lung epithelial neoplasia. Of these, SP-A is the most sensitive and specific (a possible pitfall is the need to distinguish entrapped normal pulmonary epithelial cells or alveolar macrophages from neoplastic cells) and can be used in combination with TTF-1 or napsin A to improve detection and differentiation of pulmonary carcinomas from metastatic tumors in the canine lung.

Thyroid transcription factor 1 represses the expression of Ki-67 and induces apoptosis in non-small cell lung cancer

The thyroid transcription factor 1 (TTF-1) gene is associated with the differentiation of lung epithelial cells and has been reported to be an independent prognostic factor for lung adenocarcinoma patients. The aim of the present study was to detect the expression of TTF-1 in human lung cancer cell lines and to evaluate the association of overexpressed TTF-1 with Ki-67 and apoptosis in the A549 cell line. We also investigated the expression of TTF-1 and Ki-67 in Xuanwei lung adenocarcinoma. TTF-1 mRNA expression was evaluated in 10 non-small cell lung cancer (NSCLC) cell lines by quantitative real-time RT-PCR (qRT-PCR). Overexpression of TTF-1 in A549 cells was achieved by transient transfection. The TTF-1 and Ki-67 proteins were detected by immunohistochemistry and apoptosis was detected by flow cytometry. We also investigated immunohistochemically the expression of TTF-1 and Ki-67 in 62 resected cases of Xuanwei lung adenocarcinoma. Overall the expression of TTF-1 mRNA in the 10 cell lines was low. Overexpression of TTF-1 mRNA was found only in 3 (30%) of 10 NSCLC cell lines, including 1 (25%) of 4 adenocarcinoma cell lines. A549 cells overexpressing TTF-1 were found to have repressed expression of Ki-67 (P=0.012) and increased apoptosis (P=0.000). Immunohistochemical analysis of resected cases of Xuanwei lung adenocarcinoma (n=62) showed the expression of TTF-1 in 58 (93%) of 62 and Ki-67 in 22 (35%) of 62. Patients with strong immunohistochemical expression TTF-1 were statistically associated with well-differentiated phenotype (P=0.006) and inverse correlation with Ki-67 expression (P=0.016). These data suggest that TTF-1 may serve as a tumor suppressor gene based on its inverse correlation with Ki-67 proliferative activity and increase of cellular apoptosis.

Activity and tumor specificity of human heparanase gene core promoter

Heparanase (HPSE) plays a critical role in tumor metastasis and vascularization. In addition, the human HPSE promoter has been cloned and characterized. However, the activity and specificity of the HPSE promoter in tumor cells remains unclear. The core fragment of the HPSE promoter was amplified and cloned into the multiple cloning site of the pEGFP-1 vector. The recombinant plasmid pEGFP-Hp was transfected into human umbilical vein endothelial cells (ECV304) and human hepatoma carcinoma (HepG2), laryngocarcinoma (Hep2) and chronic myelogenous leukemia (K562) cell lines. The vectors pEGFP-1 and pEGFP‑N1 were used as negative and positive controls, respectively. The activity and expression of green fluorescent protein (GFP) were analyzed. Results showed that the sequence of the amplified HPSE promoter was in agreement with the GenBank data. The recombinant plasmid pEGFP-Hp was consistent with the expected result. No GFP expression was observed in the transfected cells in the pEGFP-1 group, but a high expression was observed in the pEGFP-N1 group. As regards the pEGFP-Hp group, less fluorescence was revealed in ECV cells with a relatively high fluorescence in tumor cells. The average transfection efficiencies of pEGFP-Hp in the ECV304, HepG2, Hep2 and K562 cell lines were 3.9, 21.3, 10.8 and 6.5%, respectively, while those of pEGFP-Nl were 17.1, 24.0, 14.0 and 11.0%, respectively. The HPSE gene promoter drives the expression of downstream genes in a eukaryotic vector, specifically in tumor cell lines, but its activity is relatively weak.

B1, a novel topoisomerase II inhibitor, induces apoptosis and cell cycle G1 arrest in lung adenocarcinoma A549 cells

In our previous studies, we demonstrated that 2,6-bis-(2-chloroacetamido) anthraquinone (B1) showed a highly significant cytotoxic effect. However, its influence in the cell cycle and apoptotic induction effects has not been investigated yet. Here we report the antiproliferative effect of B1, for which IC50 values were 0.57 μmol/l for lung cancer A549 cells, 0.63 μmol/l for colon cancer HT-29 cells, and 0.53 μmol/l for breast cancer MCF-7 cells. DNA topoisomerase II (Topo II), an essential enzyme in DNA synthesis and meiotic division, is highly expressed in cancer cells. Some currently used clinical anticancer drugs (doxorubicin and mitoxantrone) targeting Topo II are very effective antineoplastic agents. B1, sharing the basic structure of known Topo II inhibitors, demonstrated a significant inhibitory effect on Topo II bioactivity. In A549 cells, B1 increased apoptotic cell population with induction of Fas, Bax, and cleaved poly(ADP-ribose) polymerase and by reduction of Bcl-2 expression. Moreover, cell cycle analysis indicated that B1 induced G1 phase arrest through modulation of G1 cell cycle regulatory proteins, such as the downregulation of cyclin D1 and upregulation of Cip/p21, Kip1/p27, and p53. Thus, our study suggests that B1, with the ability to inhibit Topo II activity and cause cell cycle G1 arrest and apoptosis, has potential as a novel anticancer agent.

Protection of CHO cells by transfer of survivin driven by ovarian-specific promoter OSP-2

Chemotherapy is the major therapy for cancer in clinic. However, chemotherapeutic agents can harm the other tissues/organs besides cancer. Thus, there are great interests in protecting the innocents by the transfer of protective genes. There are two problems to be solved, one is the selection of protective genes and the other is the orientation of the exotic genes. Recent researches demonstrated that the principal mechanism of chemotherapeutics was through apoptosis. Hereby, introduction of anti-apoptosis genes might interrupt the processes of apoptosis to avoid side effect from chemotherapeutics. On the other hand, tissue-specific promoters, which control gene expression in a tissue-specific manner, might be an alternative tool to guarantee the location of target genes. In this research, we applied gene therapy to chemoprotection using anti-apoptosis gene survivin and ovarian-specific promoter OSP-2. The results showed that OSP-2 could specifically drive the expression of survivin in ovarian cells and survivin could protect cells via inhibiting apoptosis. This might put a light on the future of chemoprotective gene therapy.

What a fish can learn from a mouse: principles and strategies for modeling human cancer in mice

This review highlights the current techniques used to generate transgenic mouse models of cancer, with an emphasis on recent advances in the use of ubiquitous promoters, models that use Cre-loxP and Flip-FRT recombinase technology, inducible systems, RNAi to target genes, and transposon mutagenesis. A concluding section discusses new imaging systems that visualize tumor progression and the microenvironment in vivo. In this review, these techniques and strategies used in mouse models of cancer are highlighted, as they are pertinent and relevant to the development of zebrafish models of cancer.

Drug-regulatable cancer cell death induced by BID under control of the tissue-specific, lung cancer-targeted TTS promoter system

Gene therapy and virotherapy are among the approaches currently being used to treat lung cancer. The success of cancer gene therapy depends on treatments where different types of tumors can be selectively targeted and destroyed without affecting normal cells and tissue. Previously, we described a promoter system (TTS) that we designed that is specifically targeted to lung cancer cells but which does not affect other types of cells including stem cells. In our study, we have enhanced the utility of the TTS system by inserting the pro-apoptotic gene BH3 domain interacting death agonist (Bid) into the TTS promoter system (TTS/Bid) to create a drug regulatable lung cancer-specific gene therapy. A recombinant adenoviral vector was used to introduce TTS/Bid (Ad-TTS/Bid) into lung cancer cells. BID expression and apoptosis occurred in A549 pulmonary adenocarcinoma cells but little Bid expression or apoptosis occurred in MCF7 breast cancer cells or in normal human lung fibroblasts. The use of cisplatin enhanced the processing of full length BID to t-BID which significantly increased lung cancer-specific cell death. In in vivo experiments, intraperitonal injection of cisplatin enhanced the antitumor effects of the vector in a lung cancer xeno-graft mouse model. Moreover, dexamethasone effectively suppressed exogenous BID expression and the antitumor effect of Ad-TTS/Bid both in vitro and in vivo. Here, we describe the efficacy of the use of cisplatin and dexamethasone with the anti lung cancer promoter system (Ad-TTS/Bid) for a safe and effective gene therapy against advanced lung cancer.

Cancer targeted gene therapy of BikDD inhibits orthotopic lung cancer growth and improves long-term survival

Lung cancer is a leading cause of cancer death due to the high incidence of metastasis; therefore novel and effective treatments are urgently needed. A current strategy is cancer specific targeted gene therapy. While many identified cancer specific promoters are highly specific, they tend to have low activity compared to the ubiquitous CMV promoter, limiting their application. We developed a targeted gene therapy expression system for lung cancer that is highly specific with strong activity. Our expression vector uses the survivin promoter, highly expressed in many cancers but not normal adult tissues. We enhanced the survivin promoter activity comparable to the CMV promoter in lung cancer cell lines using an established platform technology, while the survivin promoter remained weak in normal cells. In mouse models, the transgene was specifically expressed in the lung tumor tissue, compared with the CMV promoter that was expressed in both normal and tumor tissues. Additionally, the therapeutic gene BikDD, a mutant form of pro-apoptotic Bik, induced cell killing in vitro, and inhibited cell growth and prolonged mouse survival in vivo. Importantly, there was virtually no toxicity when BikDD was expressed with our expression system. Thus, the current report provides a therapeutic efficacy and safe strategy worthy of development in clinical trials treating lung cancer.

Suppression of surfactant protein A by an epidermal growth factor receptor tyrosine kinase inhibitor exacerbates lung inflammation

Interstitial lung disease (ILD) is reported as a serious adverse event in lung cancer patients treated with gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). However, the mechanisms of ILD associated with gefitinib remain unknown. To address the molecular mechanisms of ILD-associated gefitinib, we determined the effect of gefitinib treatment on surfactant protein expression in vitro and in vivo. Gefitinib treatment suppressed surfactant protein (SP)-A expression in H441 human lung adenocarcinoma cells expressing SP-A, -B, -C and -D by inhibiting epidermal growth factor signal. Next, gefitinib (200 mg/kg) was given p.o. to the mice daily for 1 week. Daily administration of gefitinib gradually reduced SP-A level in the bronchoalveolar lavage fluid. When lipopolysaccharide (LPS) was instilled intratracheally to the mice pretreated with gefitinib for 1 week, lung inflammation by LPS was exacerbated and prolonged. This exacerbation of lung inflammation was rescued by intranasal administration of SP-A. These results demonstrated that pretreatment with gefitinib exacerbated LPS-induced lung inflammation by reducing SP-A expression in the lung. This study suggests that epidermal growth factor receptor tyrosine kinase inhibitor may reduce SP-A expression in the lungs of lung cancer patients and thus patients treated with epidermal growth factor receptor tyrosine kinase inhibitor may be susceptible to pathogens.

Anti-CD3 scFv-B7.1 fusion protein expressed on the surface of HeLa cells provokes potent T-lymphocyte activation and cytotoxicityThis paper is one of a selection of papers in this Special Issue, entitled International Symposium on Recent Advances in Molecular, Clinical, and Social Medicine, and has undergone the Journal's usual peer-review process

The targeting of tumor cells by cytotoxic T lymphocytes is a promising strategy for biotherapy, but T cells require 2 signals via the T-cell receptor – CD3 complex and CD28 molecules for activation. To bridge the gap between cytotoxic T lymphocytes and tumor cells, our objective in this study was to describe the construction and the cell surface-anchored expression of a fusion protein, anti-CD3 scFv-B7.1, derived from inserting a fusion gene encoding anti-CD3 scFv and the extra-cellular domain of B7.1 fused by the splicing by overlap extension method into a mammalian expression vector, pDisplay. Transfection of the recombinant vector by electroporation into HeLa cells resulted in the production of protein migrating at approximately 57 kDa under reducing conditions. The expressed fusion protein could bind to T lymphocytes and induce strong T-cell activation. Meanwhile, a potent cytotoxicity was induced in the mixed culture of T-cell-modified tumor cells in a 96 h methyl-thiazolyl-diphenyl tetrazolium bromide assay. Our results indicate that this bifunctional protein, through activating T lymphocytes to lyse homologous human carcinomas, may be of potential value for T-cell-based immunotherapeutical treatment protocols in vivo.