Wild-type p53 enhances the cytotoxic effect of radionuclide gene therapy using sodium iodide symporter in a murine anaplastic thyroid cancer model

Cancer biotherapy: review and prospect

Malignant tumors pose a grave threat to the quality of human life. The prevalence of malignant tumors in China is steadily rising. Presently, clinical interventions encompass surgery, radiotherapy, and pharmaceutical therapy in isolation or combination. Nonetheless, these modalities fail to completely eradicate malignant tumor cells, frequently leading to metastasis and recurrence. Conversely, tumor biotherapy has emerged as an encouraging fourth approach in preventing and managing malignant tumors owing to its safety, efficacy, and minimal adverse effects. Currently, a range of tumor biotherapy techniques are employed, including gene therapy, tumor vaccines, monoclonal antibody therapy, cancer stem cell therapy, cytokine therapy, and adoptive cellular immunotherapy. This study aims to comprehensively review the latest developments in biological treatments for malignant tumors.

A Review on Tumor Control Probability (TCP) and Preclinical Dosimetry in Targeted Radionuclide Therapy (TRT)

Targeted radionuclide therapy (TRT) uses radiopharmaceuticals to specifically irradiate tumor cells while sparing healthy tissue. Response to this treatment highly depends on the absorbed dose. Tumor control probability (TCP) models aim to predict the tumor response based on the absorbed dose by taking into account the different characteristics of TRT. For instance, TRT employs radiation with a high linear energy transfer (LET), which results in an increased effectiveness. Furthermore, a heterogeneous radiopharmaceutical distribution could result in a heterogeneous dose distribution at a tissue, cellular as well as subcellular level, which will generally reduce the tumor response. Finally, the dose rate in TRT is protracted, relatively low, and variable over time. This allows cells to repair more DNA damage, which may reduce the effectiveness of TRT. Within this review, an overview is given on how these characteristics can be included in TCP models, while some experimental findings are also discussed. Many parameters in TCP models are preclinically determined and TCP models also play a role in the preclinical stage of radiopharmaceutical development; however, this all depends critically on the calculated absorbed dose. Accordingly, an overview of the existing preclinical dosimetry methods is given, together with their limitation and applications. It can be concluded that although the theoretical extension of TCP models from external beam radiotherapy towards TRT has been established quite well, the experimental confirmation is lacking. Thus, requiring additional comprehensive studies at the sub-cellular, cellular, and organ level, which should be provided with accurate preclinical dosimetry.

Therapeutic advances in anaplastic thyroid cancer: a current perspective

Thyroid cancer incidence is increasing at an alarming rate, almost tripling every decade. In 2017, it was the fifth most common cancer in women. Although the majority of thyroid tumors are curable, about 2-3% of thyroid cancers are refractory to standard treatments. These undifferentiated, highly aggressive and mostly chemo-resistant tumors are phenotypically-termed anaplastic thyroid cancer (ATC). ATCs are resistant to standard therapies and are extremely difficult to manage. In this review, we provide the information related to current and recently emerged first-line systemic therapy (Dabrafenib and Trametinib) along with promising therapeutics which are in clinical trials and may be incorporated into clinical practice in the future. Different categories of promising therapeutics such as Aurora kinase inhibitors, multi-kinase inhibitors, epigenetic modulators, gene therapy using oncolytic viruses, apoptosis-inducing agents, and immunotherapy are reviewed. Combination treatment options that showed synergistic and antagonistic effects are also discussed. We highlight ongoing clinical trials in ATC and discuss how personalized medicine is crucial to design the second line of treatment. Besides using conventional combination therapy, embracing a personalized approach based on advanced genomics and proteomics assessment will be crucial to developing a tailored treatment plan to improve the chances of clinical success.

Sodium Iodide Symporter (NIS) in the Management of Patients with Thyroid Carcinoma

Although radioiodine has been applied in thyroid diseases including carcinoma for over 70 years, it was only in 1996 that the basic molecular mechanism of iodine uptake was identified. Iodide is actively transported into the thyroid via a membrane glycoprotein known as sodium iodide symporter (NIS). NIS mediates radioiodine uptake into thyroid normal and cancer cells. The knowledge on NIS expression has provided scientific background to the empirical management of thyroid carcinoma. Based on recent studies of the NIS gene, this paper provides current clinical applications and future studies.

Reintroducing the Sodium-Iodide Symporter to Anaplastic Thyroid Carcinoma

BACKGROUND

Anaplastic thyroid carcinoma (ATC), the most aggressive form of thyroid cancer, is unresponsive to radioiodine therapy. The current study aimed to extend the diagnostic and therapeutic application of radioiodine beyond the treatment of differentiated thyroid cancer by targeting the functional sodium-iodide symporter (NIS) to ATC.

METHODS

The study employed nanoparticle vectors (polyplexes) based on linear polyethylenimine (LPEI), shielded by polyethylene glycol (PEG) and coupled to the synthetic peptide GE11 as an epidermal growth factor receptor (EGFR)-specific ligand in order to target a NIS-expressing plasmid (LPEI-PEG-GE11/NIS) to EGFR overexpressing human thyroid carcinoma cell lines. Using ATC xenograft mouse models, transfection efficiency by ¹²³I scintigraphy and potential for systemic radioiodine therapy after systemic polyplex application were evaluated.

RESULTS

In vitro iodide uptake studies in SW1736 and Hth74 ATC cells, and, for comparison, in more differentiated follicular (FTC-133) and papillary (BCPAP) thyroid carcinoma cells demonstrated high transfection efficiency and EGFR-specificity of LPEI-PEG-GE11/NIS that correlated well with EGFR expression levels. After systemic polyplex injection, in vivo ¹²³I gamma camera imaging revealed significant tumor-specific accumulation of radioiodine in an SW1736 and an Hth74 xenograft mouse model. Radioiodine accumulation was found to be higher in SW1736 tumors, reflecting in vitro results, EGFR expression levels, and results from ex vivo analysis of NIS staining. Administration of ¹³¹I in LPEI-PEG-GE11/NIS-treated SW1736 xenograft mice resulted in significantly reduced tumor growth associated with prolonged survival compared to control animals.

CONCLUSIONS

The data open the exciting prospect of NIS-mediated radionuclide imaging and therapy of ATC after non-viral reintroduction of the NIS gene. The high tumor specificity after systemic application makes the strategy an attractive alternative for the treatment of highly metastatic ATC.

Inverse Agonist of Estrogen-Related Receptor γ Enhances Sodium Iodide Symporter Function Through Mitogen-Activated Protein Kinase Signaling in Anaplastic Thyroid Cancer Cells

Anaplastic thyroid cancer (ATC), a rare thyroid cancer with poor prognosis, is associated with insufficient function of the sodium iodide symporter (NIS). Estrogen-related receptor γ (ERRγ) is a member of the orphan nuclear receptors with important functions in cell development and homeostasis. However, there are no reports that demonstrate whether ERRγ is related to NIS function. Here, we evaluated the role of ERRγ in the regulation of NIS function in ATC cells using GSK5182, an inverse agonist of ERRγ.

METHODS

Two ATC cell lines, BHT-101 and CAL62, were incubated with GSK5182 at various time points and doses. The NIS function in the ATC cells was serially assessed by their uptake of radioiodine. The effects of GSK5182 on ERRγ and the mitogen-activated protein (MAP) kinase pathway, as well as on NIS protein, were evaluated by immunoblot assay. To examine whether the GSK5182-induced NIS functional activity can be affected by inhibition of the MAP kinase pathway, the MAP kinase activity and levels of radioiodine uptake were determined after application of a mitogen-activated protein kinase kinase (MEK) inhibitor to GSK5182-treated cells. Finally, the cytotoxic effect of (131)I was determined by clonogenic assay.

RESULTS

Treatment with GSK5182 resulted in dose- and time-dependent increases in iodide uptake in ATC cells, which were accompanied by both the downregulation of ERRγ protein and the activation of extracellular signal-regulated kinase (ERK) 1/2. Both the increased radioiodine uptake and ERK1/2 activation of ATC cells were completely inhibited by the specific MEK inhibitor. GSK5182 treatment enhanced the membrane localization of NIS in both ATC cell lines. Accordingly, preexposure to GSK5182 enhanced the cytotoxic effects of (131)I treatment in ATC cells.

CONCLUSION

These findings suggest that the inverse agonist of ERRγ enhances the responsiveness of radioiodine therapy by modulating NIS function in ATC cells via the regulation of ERRγ and the MAP kinase signaling pathway.

Novel approaches in anaplastic thyroid cancer therapy

Anaplastic thyroid cancer (ATC), accounting for less than 2% of all thyroid cancer, is responsible for the majority of death from all thyroid malignancies and has a median survival of 6 months. The resistance of ATC to conventional thyroid cancer therapies, including radioiodine and thyroid-stimulating hormone suppression, contributes to the very poor prognosis of this malignancy. This review will cover several cellular signaling pathways and mechanisms, including RET/PTC, RAS, BRAF, Notch, p53, and histone deacetylase, which are identified to play roles in the transformation and dedifferentiation process, and therapies that target these pathways. Lastly, novel approaches and agents involving the Notch1 pathway, nuclear factor κB, Trk-fused gene, cancer stem-like cells, mitochondrial mutation, and tumor immune microenvironment are discussed. With a better understanding of the biological process and treatment modality, the hope is to improve ATC outcome in the future.

Gene therapy in endocrine tumors: a comprehensive overview

Effective treatment strategies that help tackle the complex problems associated with managing endocrine cancers are in great demand. Because of the shortcomings in current treatments and the problems associated with the treatment strategies used in the cure and/or management of endocrine cancers, considerable effort must be devoted to developing new and effective therapeutic strategies. Gene therapy represents an area of both basic and clinical research that can potentially be considered a therapeutic option in treating endocrine cancers. Therefore, we consider it timely to summarize the studies related to gene-therapy interventions that are available for treating endocrine cancers and to highlight the major limitations of and the recent progress made in these therapies. After systematically reviewing the literature, we provide a comprehensive overview of distinct studies conducted to evaluate gene-therapy approaches in various endocrine cancers. Some of these successful studies have been extended toward translational investigations. The emerging view is that an integrative approach is required to combat the pitfalls associated with gene-therapy studies, especially in endocrine cancers.

p53-dependent radiobiological responses to internalised indium-111 in human cells

INTRODUCTION

The p53 tumour suppressor protein plays a pivotal role in the response of mammalian cells to DNA damage. It regulates cell cycle progression, apoptosis and DNA repair mechanisms and is therefore likely to influence response to targeted radionuclide therapy. This study investigated the role of p53 in the cellular response to the Auger-emitting radionuclide indium-111.

METHODS

Two stable clones of a HT1080 fibrosarcoma cell line, differing only in p53 status due to RNAi-mediated knockdown of p53 expression, were incubated for 1 h with [¹¹¹In]-oxinate (0-10 MBq/ml). Radiopharmaceutical uptake into HT1080 cells was measured in situ using a non-contact phosphorimager method. Cellular sensitivity and DNA damage were measured by, respectively, clonogenic survival analysis and the single cell gel electrophoresis (Comet) assay.

RESULTS

Mean uptake of [¹¹¹In]-oxinate in HT1080 cells was unaffected by p53 status, reaching a maximum of 9Bq/cell. [¹¹¹In]-oxinate-induced cytotoxicity was also identical in both clones, as measured by IC50 (0.68 MBq/ml). However the formation of DNA damage, measured immediately after treatment with [¹¹¹In]-oxinate, was found to be up to 2.5-fold higher in the p53-deficient HT1080 clone.

CONCLUSIONS

The increased DNA damage induced in p53-deficient HT1080 cells suggests an early deficiency in the repair of DNA damage during the treatment period. However, the similarity in cellular sensitivity, irrespective of p53 status, suggests that reduced p53 leads to a concomitant reduction in p53-dependent cytotoxicity despite the persistence of DNA damage. The results may provide insight into how tumours that differ in p53 status respond to therapeutic radionuclides.

Sodium iodide symporter for nuclear molecular imaging and gene therapy: from bedside to bench and back

Molecular imaging, defined as the visual representation, characterization and quantification of biological processes at the cellular and subcellular levels within intact living organisms, can be obtained by various imaging technologies, including nuclear imaging methods. Imaging of normal thyroid tissue and differentiated thyroid cancer, and treatment of thyroid cancer with radioiodine rely on the expression of the sodium iodide symporter (NIS) in these cells. NIS is an intrinsic membrane protein with 13 transmembrane domains and it takes up iodide into the cytosol from the extracellular fluid. By transferring NIS function to various cells via gene transfer, the cells can be visualized with gamma or positron emitting radioisotopes such as Tc-99m, I-123, I-131, I-124 and F-18 tetrafluoroborate, which are accumulated by NIS. They can also be treated with beta- or alpha-emitting radionuclides, such as I-131, Re-186, Re-188 and At-211, which are also accumulated by NIS. This article demonstrates the diagnostic and therapeutic applications of NIS as a radionuclide-based reporter gene for trafficking cells and a therapeutic gene for treating cancers.

Recurrent thyroid cancer with changing histologic features

We present the case of a 57-year-old woman diagnosed with breast cancer and a thyroid mass that was suspicious for cancer. The breast cancer was estrogen and progesterone receptor negative, HER2/neu borderline, with a high proliferative index. Treatment of this cancer took precedence. Nine months later, a total thyroidectomy was done for papillary thyroid cancer with metastases to 2 of 8 perithyroid lymph nodes. Postoperative radioactive iodine ablation was given. Recurrent thyroid disease was found in the right neck 1 year later and was resected; no radioactive iodine was given at that time. After 2½ years, the cancer recurred as a more highly aggressive, undifferentiated anaplastic thyroid carcinoma. Treatment is discussed.