Adenovirus-mediated tumor suppressor p53 gene therapy for anaplastic thyroid carcinoma in vitro and in vivo

Looking at Thyroid Cancer from the Tumor-Suppressor Genes Point of View

Thyroid cancer is the most frequent endocrine malignancy and accounts for approximately 1% of all diagnosed cancers. A variety of mechanisms are involved in the transformation of a normal tissue into a malignant one. Loss of tumor-suppressor gene (TSG) function is one of these mechanisms. The normal functions of TSGs include cell proliferation and differentiation control, genomic integrity maintenance, DNA damage repair, and signaling pathway regulation. TSGs are generally classified into three subclasses: (i) gatekeepers that encode proteins involved in cell cycle and apoptosis control; (ii) caretakers that produce proteins implicated in the genomic stability maintenance; and (iii) landscapers that, when mutated, create a suitable environment for malignant cell growth. Several possible mechanisms have been implicated in TSG inactivation. Reviewing the various TSG alteration types detected in thyroid cancers may help researchers to better understand the TSG defects implicated in the development/progression of this cancer type and to find potential targets for prognostic, predictive, diagnostic, and therapeutic purposes. Hence, the main purposes of this review article are to describe the various TSG inactivation mechanisms and alterations in human thyroid cancer, and the current therapeutic options for targeting TSGs in thyroid cancer.

Survival Benefit of Intervention Treatment in Advanced Anaplastic Thyroid Cancer

Background

The management of anaplastic thyroid cancer (ATC) is controversial; thus, proper treatment and prognostic factors should be investigated.

Objectives

To compare the survival outcomes of the intervention and palliative treatment in ATC patients.

Methods

A hospital-based retrospective study was conducted at a single tertiary university hospital. The medical record charts were retrieved from November 20, 1987, to December 31, 2016. The final follow-up ended by December 31, 2017. The patients' demographic data, laboratory data, clinical presentation, and treatment modality results were analyzed.

Results

One hundred twenty-one records were analyzed with a one-year overall survival rate of 3.5% (median survival time: 77 days); however, 16 cases had insufficient data to classify staging and treatment modalities. Therefore, 105 ATC patients (37 with stage IVa, 39 with stage IVb, and 29 with stage IVc disease) were included with a one-year overall survival rate of 4.0% (median survival time of 82 days). Intervention treatment allowed longer median survival times (p < 0.05) and a better survival rate (p < 0.05). Among the interventional treatment groups, postoperative chemoradiation yielded the longest median survival time (187 days) and the highest survival rate (20%) (p < 0.05). The intervention modality allowed a better median survival time at all stages, particularly in stage IVa (p < 0.05). Unfavorable prognostic factors were adjusted for in a multiple Cox regression model showing that significant factors included age ≥65 years (hazard ratio HR: 2.57), palliative treatment (HR: 1.85), and leukocytosis ≥10,000 cells/mm³ (HR: 2.76).

Conclusions

Intervention treatment provided a better survival outcome in all stages, particularly in stage IVa, with a significantly better median survival time. Among interventional treatments, postoperative chemoradiation led to the longest survival rate, suggesting that this treatment should be considered in ATC patients with resectable tumors and no poor prognostic factors, such as older age and leukocytosis.

Molecular aberrations and signaling cascades implicated in the pathogenesis of anaplastic thyroid cancer

Anaplastic Thyroid Cancer (ATC) accounts for >40% thyroid cancer-related deaths and has a dismal prognosis. In the past decade, significant efforts have been made towards understanding the pathogenesis of this disease and developing novel therapeutics. Unfortunately, effective treatment is still lacking and a more thorough understanding of ATC pathogenesis may provide new opportunities to improve ATC therapeutics. This review provides insights into ATC clinical presentation and pathology, and the putative role of genetic aberrations and alterations in molecular signaling pathways in ATC pathogenesis. We reviewed prevalent mutations, chromosomal abnormalities and fusions, epigenetic alterations and dysregulations in ATC, and highlighted several signaling cascades which appeared to be integral to ATC pathogenesis. Moreover, these features offer insights into de-differentiated, aggressive and drug-resistant phenotype of ATC, and thus may help in exploring potential new molecular targets for developing novel therapeutics.

Integrated Therapeutic Strategies for Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) is a very rare neoplasm with an aggressive course. The prognosis has not changed in the last decades and the median survival does not exceed six months. Only few patients with incidental limited ATC will be cured. Different therapeutic options have been explored but the results are disappointing. At present, new drugs and new timing for proper treatment are under investigation. In this short review we have summarized these recent developments.

Poorly Differentiated and Anaplastic Thyroid Cancer

BACKGROUND

Poorly differentiated thyroid carcinoma (PDTC) and anaplastic (undifferentiated) thyroid carcinoma (ATC) comprise a small subset of thyroid tumors that are associated with a poor prognosis and account for a significant portion of the morbidity and mortality related to thyroid cancer. Since management strategies vary between these two entities, it is important for clinicians to be able to differentiate PDTC from ATC.

METHODS

We reviewed the literature on PDTC and ATC and compared clinical and histopathologic features important in defining the disease process.

RESULTS

Both PDTC and ATC display aggressive behavior with increased locoregional and distant disease. In most cases, patients are older and have large, locally advanced tumors. PDTC may represent an intermediate entity in the progression of well-differentiated thyroid carcinoma to ATC. The use of surgical management may be curative or palliative and differs between PDTC and ATC. The roles of radiotherapy and chemotherapy have not been well described.

CONCLUSIONS

PDTC and ATC are rare diseases that carry a poor prognosis. Recognition of their different clinicopathologic features is important to the optimal management of these tumors.

The management of thyroid nodules and cancer in the molecular era

The incidence of thyroid cancer is increasing worldwide. Current standards in the diagnosis and management of thyroid cancer are limited by the uncertainty of fine-needle aspiration samples that are indeterminate in nature. Molecular markers have the potential to improve the accuracy of thyroid fine-needle aspiration and to aid the physician in giving a more accurate diagnosis and prognosis. This paper summarizes the various molecular markers currently available.

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.

Clinical implications of molecular markers in follicular cell-derived thyroid cancer

The increasing use/applications of molecular biology techniques have provided new insights on the genetic changes that underlie carcinogenesis and tumor progression in thyroid cancer. Molecular analysis may improve the histopathologic evaluation of follicular cell-derived thyroid carcinoma, not only elucidating some unresolved problems related to the diagnosis and disease prognosis, but also by improving patient management. Besides increasing our comprehension of cancer biology, either genetic alterations or gene expression profiles implicated in thyroid carcinogenesis shed new light on innovative diagnostic procedures as well as on targeted therapies.

Gal-3 is stimulated by gain-of-function p53 mutations and modulates chemoresistance in anaplastic thyroid carcinomas

Galectin-3 (Gal-3) is an anti-apoptotic molecule of the beta-galactoside-binding lectin family. Gal-3 is down-regulated by wt-p53 and this repression is required for p53-induced apoptosis. Since poorly differentiated thyroid carcinomas (PDTCs) and anaplastic thyroid carcinomas (ATCs) frequently harbour p53 mutations, we asked whether Gal-3 expression and activity could be influenced by such mutations in these tumours. We found a positive correlation between Gal-3 expression and p53 mutation in human thyroids and in thyroid carcinoma cell lines (TCCLs) harbouring different p53 mutations. Gal-3 was over-expressed in most ATCs and TCCLs, especially those with the most frequently detected p53 mutation (p53(R273H)). Over-expression of p53(R273H) in two p53-null cells (SAOS-2 and SW-1736) as well as in two wt-p53-carrying TCCLs (TPC-1 and K1), stimulated Gal-3 expression, while interference with p53(R273H) endogenous expression in ARO cells down-regulated Gal-3 expression. Conversely, over-expression of wt-p53 in ARO cells restored the inhibitory effect on Gal-3 expression. ARO cells are highly resistant to apoptosis and express both p53 and Gal-3, which are increased upon cisplatin treatment. Interference with Gal-3 expression in these cells stimulated their chemosensitivity. In conclusion, gain-of-function p53 mutant acquires the de novo ability to stimulate Gal-3 expression and to increase chemoresistance in ATCs.

Re-expression of ABI3-binding protein suppresses thyroid tumor growth by promoting senescence and inhibiting invasion

Loss of ABI gene family member 3-binding protein (ABI3BP) expression may be functionally involved in the pathogenesis of cancer. Previous reports have indicated a loss of expression in lung cancer and a presumed role in inducing cellular senescence. We show here that ABI3BP expression is significantly decreased in most malignant thyroid tumors of all types. To better understand ABI3BP's role, we created a model by re-expressing ABI3BP in two thyroid cancer cell lines. Re-expression of ABI3BP in thyroid cells resulted in a decrease in transforming activity, cell growth, cell viability, migration, invasion, and tumor growth in nude mice. ABI3BP re-expression appears to trigger cellular senescence through the p21 pathway. Additionally, ABI3BP induced formation of heterochromatin 1-binding protein gamma-positive senescence-associated (SA) heterochromatin foci and accumulation of SA beta-galactosidase. The combination of a decrease in cell growth, invasion, and other effects upon ABI3BP re-expression in vitro helps to explain the large reduction in tumor growth that we observed in nude mice. Together, our data provide evidence that the loss of ABI3BP expression could play a functional role in thyroid tumorigenesis. Activation of ABI3BP or its pathway may represent a possible basis for targeted therapy of certain cancers.

Thyroid-stimulating hormone/cAMP-mediated proliferation in thyrocytes

Current research on thyrotropin-activated proliferation in the thyrocyte needs to be aimed at a better understanding of crosstalk and negative-feedback mechanisms with other proliferative pathways, especially the insulin/IGF-1-induced phosphoinositol-3 kinase pathway and the serum-induced MAPK or Wnt pathways. Convergence of proliferative pathways in mTOR is a hotspot of current research, and combined treatment using double class inhibitors for thyroid cancer may bring some success. New thyroid-stimulating hormone receptor (TSHR)-interacting proteins, a better picture of cAMP targets, a deeper knowledge of the action of the protein kinase A regulatory subunits, especially their interactions with the replication machinery, and a further understanding of mechanisms that lead to cell cycle progression through G₁/S and G₂/M checkpoints are areas that need further elucidation. Finally, massive information coming from microarray data analysis will prompt our understanding of thyroid-stimulating hormone-promoted thyrocyte proliferation in health and disease.

TAp73 alpha increases p53 tumor suppressor activity in thyroid cancer cells via the inhibition of Mdm2-mediated degradation

p53 family proteins include p53 tumor suppressor, p63, and p73. Despite the high similarity in structure and function with p53, p63, and p73 function in tumor suppression is still controversial. Here, we show that TAp73alpha, a transcriptionally active p73 isoform, is able to synergize p53 tumor suppressor function in thyroid cancer cells. Indeed, depletion of p73 by small interfering RNA in thyroid cancer cells resulted in a reduced transcriptional activity of p53. Ectopic coexpression of both p53 and TAp73alpha in thyroid cancer cells resulted in increased transcription and tumor suppressor function compared with p53 or TAp73alpha alone, as well as in increased p53 protein levels. The enhancing effect of TAp73alpha on p53 activity is Mdm2 dependent because it is prevented by Mdm2 depletion by small interfering RNA. At least two mechanisms may explain the interference of TAp73alpha with p53 function. First, in thyroid cancer cells, TAp73alpha inhibits the effect of p53 on Mdm2 induction by antagonizing p53 at the Mdm2 promoter level. Second, a TAp73alpha mutant (G264W), which is devoid of DNA binding capability, is still able to increase p53 protein levels by competing with p53 for Mdm2 protein binding. Taken together, these results indicate that in thyroid cancer cells, TAp73alpha is able to increase p53 protein level and function by interfering with Mdm2-mediated p53 degradation. These results may be useful for designing gene therapies aimed at restoring a normal p53 function in thyroid cancer cells.

Surgical options in undifferentiated thyroid carcinoma

Undifferentiated or anaplastic carcinoma is an uncommon histologic type of thyroid cancer. It is one of the most aggressive malignancies associated with a poor prognosis. Most patients are elderly presenting as locally advanced disease with nodal and distant metastases. Complete surgical resection is frequently not possible and there is no effective systemic therapy. Aggressive multimodal therapy including surgery, radiation, and chemotherapy is recommended for management. However, because of the rarity of the disease, its aggressiveness and the lack of prospective treatment protocols, nearly all evidence in the literature comes from retrospective case series or cohort studies for selected patients' subgroups treated over a relatively long study period. Evidence of therapeutic benefit of one treatment option over another is lacking. Prognosis remains dismal with a median survival of 2-12 months Surgery remains an important component of the multimodal therapy and is commonly adopted as primary treatment. Although radical resection should be discouraged, resection without inducing significant morbidity can be considered for good risk patients with resectable tumors. It provides an effective form of palliation with potential cure when combined with postoperative radiotherapy and/or chemotherapy. Patients selected for surgical resection was frequently identified to have improved survival. A regime of preoperative hyperfractionated radiotherapy and doxorubicin followed by surgery when feasible has been documented to achieve local control and avoid tracheostomy for ATC patients. Because of the ineffectiveness of all conventional treatment modalities, novel molecular targeted therapies are being developed to tackling this uniformly fatal disease with promising results.

Cell-based imaging of sodium iodide symporter activity with the yellow fluorescent protein variant YFP-H148Q/I152L

The sodium iodide symporter (NIS) mediates iodide (I−) transport in the thyroid gland and other tissues and is of increasing importance as a therapeutic target and nuclear imaging reporter. NIS activity in vitro is currently measured with radiotracers and electrophysiological techniques. We report on the development of a novel live cell imaging assay of NIS activity using the I−-sensitive and genetically encodable yellow fluorescent protein (YFP) variant YFP-H148Q/I152L. In FRTL-5 thyrocytes stably expressing YFP-H148Q/I152L, I− induced a rapid and reversible decrease in cellular fluorescence characterized by 1) high affinity for extracellular I− (35 μM), 2) inhibition by the NIS inhibitor perchlorate, 3) extracellular Na+ dependence, and 4) TSH dependence, suggesting that fluorescence changes are due to I− influx via NIS. Individual cells within a population of FRTL-5 cells exhibited a 3.5-fold variation in the rate of NIS-mediated I− influx, illustrating the utility of YFP-H148Q/I152L to detect cell-to-cell difference in NIS activity. I− also caused a perchlorate-sensitive decrease in YFP-H148Q/I152L fluorescence in COS-7 cells expressing NIS but not in cells lacking NIS. These results demonstrate that YFP-H148Q/I152L is a sensitive biosensor of NIS-mediated I− uptake in thyroid cells and in nonthyroidal cells following gene transfer and suggest that fluorescence detection of cellular I− may be a useful tool by which to study the pathophysiology and pharmacology of NIS.

New trends in the treatment of undifferentiated carcinomas of the thyroid

INTRODUCTION

Malignant tumours of the thyroid are generally classified as either well-differentiated thyroid carcinoma, which is composed of papillary and follicular carcinoma, or undifferentiated/anaplastic thyroid carcinoma (ATC). ATC is not only the most lethal disease in the field of endocrine surgery but also one of the most aggressive tumours characterized by an almost invariable fatal outcome, which only very rarely exceeds a 1-year course.

DISCUSSION

The impact of surgical resection in association with external beam radiation on ATC outcome has been extensively investigated also in studies based on multicentric database, and there is a general agreement on the significance of a complete resection of the tumour. It has been difficult up to now to collect data regarding chemotherapy adjuvant treatment. In spite of the lack of an extensive review about the results of this kind of treatment by itself or as part of a multimodal approach, it seems that among the several chemotherapy agents experienced, none proved to influence significantly ATC prognosis. Neither doxorubicin (the most commonly used) nor other drugs, such as cisplatin, bleomycin, fluorouracil or cyclophosphamide, showed any real efficacy in controlling the disease.

CONCLUSION

The most recent development in this field seems to be represented by the possibility offered by PPARg agonists; even more promising might be the use of adenovirus-mediated p53 tumour suppressor gene therapy or BMP-7. All these new therapies need further confirmation coming from ongoing clinical trials such as those involving the use of vascular and growth factor-targeted agents.

The C-terminal CD47/IAP-binding domain of thrombospondin-1 prevents camptothecin- and doxorubicin-induced apoptosis in human thyroid carcinoma cells

Camptothecin and doxorubicin belong to a family of anticancer drugs that exert cytotoxic effects by triggering apoptosis in various cell types. However there have only been few investigations showing that matricellular proteins like thrombospondin-1 (TSP-1) could be involved in the underlying mechanism of this cytotoxicity. In this report, using Hoechst reagent staining, reactive oxygen species production and caspase-3 activity measurement, we determined that both camptothecin and doxorubicin induced apoptosis in human thyroid carcinoma cells (FTC-133). On the one hand, we demonstrated that camptothecin and doxorubicin inhibited TSP-1 expression mainly occurring at the transcriptional level. On the other hand, drug-induced apoptosis determined by western blot analysis for PARP cleavage and caspase-3 activity measurement, was significantly decreased in presence of exogenous TSP-1. In order to identify the sequence responsible for this effect, we used the CD47/IAP-binding peptide 4N1 (RFYVVMWK), derived from the C-terminal domain of TSP-1, and known to play a role in apoptosis. Thus, in presence of 4N1, camptothecin and doxorubicin-induced pro-apoptotic activity was considerably inhibited. These findings suggest that induction of apoptosis by camptothecin or doxorubicin in FTC-133 cells is greatly dependent by a down-regulation of TSP-1 expression and shed new light on a possible role for TSP-1 in drug resistance.

Gene therapy for thyroid cancer

Although most thyroid cancers may be cured by surgery and ¹³¹I therapy, approximately 10-20% of patients die from advanced differentiated and anaplastic tumors that are unresponsive to conventional treatments. Thus, alternative approaches such as gene therapy are of interest, especially using targeted therapeutic gene delivery. Several strategies have been designed specifically for thyroid cancer and some have proven to be feasible in preclinical studies. In particular, it is suggested that combined gene therapy approaches, as well as multimodality therapeutic regimens, including gene therapy and conventional treatments, should be pursued to achieve clinically significant results. The recent discovery of new markers of thyroid cancer should improve the efficacy of gene therapy.

Anaplastic Thyroid Carcinoma: Biology, Pathogenesis, Prognostic Factors, and Treatment Approaches

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumors known to affect humans and carries a dismal prognosis. Our primary aim was to review its epidemiology, biology, risk factors, and prognostic indicators. We also reviewed the individual and combined roles of surgery, radiotherapy, chemotherapy, and newer therapeutic options in the management of ATC.

METHODS

An extensive literature review was conducted to include all published reports on ATC. The changing trends in the management of anaplastic thyroid cancer were analyzed to summarize the current practice of management of ATC.

RESULTS

Although ATC is rare, there has been a decline in its incidence worldwide. ATC accounts for more than half of the 1200 deaths per year attributed to thyroid cancer. Long-term survivors are rare, with >75% and 50% of patients harboring cervical nodal disease and metastatic disease, respectively, at presentation. ATC can arise de novo or from preexisting well-differentiated thyroid cancer. Surgical management has shifted from tracheostomy only for palliation to curative resection when possible. Tracheostomy is performed for impending obstruction rather than for prophylaxis. Radiotherapy has evolved from postoperative administration only to preoperative treatment, combining preoperative and postoperative treatment and using higher doses, along with hyperfractionating and accelerating dose schedules. Chemotherapy has changed from monotherapy to combination therapy, and newer drugs such as paclitaxel show promise. Similarly, novel angiogenesis-inhibiting agents are currently being used, with early reports of some benefit.

CONCLUSIONS

Despite multimodality approaches, ATC still carries a dismal prognosis. This should provoke innovative strategies beyond conventional methods to tackle this uniformly lethal disease.

Vitamin D3 treatment for locally advanced thyroid cancer: a case report

There are many intricacies in the surgical treatment of locally advanced thyroid cancer, including the medical management of the remaining functional organ and any cosmetic impairments, which are sometimes very difficult to manage and eventually carry a relatively high morbidity and mortality. Here, we report on a case of a 65-year-old female with an extremely locally-advanced thyroid cancer involving both lobes of the thyroid, blood vessels, trachea and esophagus. Despite the severity of her condition, oral administration of vitamin D3 (alphacalcido) has stalled both the tumor growth and further increases of serum thyroglobulin (Tg) level, and has led to a good preservation of quality of life for the last two years. Several reports have previously demonstrated the efficacy of vitamin D3 to inhibit the proliferation of thyroid cancer cell lines in vitro, but clinical evidence has been limited so far. Therefore, this case report provides important evidence for the effectiveness of vitamin D3 therapy against advanced thyroid cancers.

Modulation of retrovirally driven therapeutic genes by mutant TP53 in anaplastic thyroid carcinoma

We previously demonstrated that restoration of TP53 activity in anaplastic thyroid carcinoma inhibits cell growth and induces expression of thyroid differentiation markers. Here, we investigated whether TP53 status may condition the expression of therapeutic genes driven by retroviral LTR or tissue-specific enhancer elements. The TP53-defective ARO anaplastic thyroid carcinoma cells were transfected with TP53(Val135), which exhibits wild-type activity at 32 degrees C, and transduced with retroviral vectors, in which therapeutic genes were driven either by wild-type LTR or by a reshuffled LTR containing thyroglobulin (TG) enhancer. Both at 37 and 32 degrees C, expression of transgenes driven by TG enhancer was 10-fold lower than that obtained with wild-type LTR retroviral vector. TP53(Val135) transfer into ARO cells repressed transcription from wild-type LTR but increased expression of TG-driven therapeutic genes. This effect was markedly enhanced by cell culture at 32 degrees C and by TSH treatment. Cytotoxic effects shown after ganciclovir treatment paralleled therapeutic gene expression levels. In conclusion, TP53 status in the tumor cell can influence expression of therapeutic genes. When using retroviral-vector-based gene therapy, wild-type LTR vectors should be employed to target TP53-defective tumors, whereas thyroid-specific promoters should be used for transcriptional targeting of thyroid carcinomas carrying wild-type TP53.

Cytotoxic effects of gemcitabine-loaded liposomes in human anaplastic thyroid carcinoma cells

BACKGROUND

Identification of effective systemic antineoplastic drugs against anaplastic thyroid carcinomas has particularly important implications. In fact, the efficacy of the chemotherapeutic agents presently used in these tumours, is strongly limited by their low therapeutic index.

METHODS

In this study gemcitabine was entrapped within a pegylated liposomal delivery system to improve the drug antitumoral activity, thus exploiting the possibility to reduce doses to be administered in cancer therapy. The cytotoxic effects of free or liposome-entrapped gemcitabine was evaluated against a human thyroid tumour cell line. ARO cells, derived from a thyroid anaplastic carcinoma, were exposed to different concentrations of the drug. Liposomes formulations were made up of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/cholesterol/1,2-distearoyl-sn-glycero-3-phosphoethanolamine-MPEG (8:3:1 molar ratio). Cell viability was assessed by both trypan bleu dye exclusion assay and fluorimetric analysis of cell DNA content.

RESULTS

A cytotoxic effect of free gemcitabine was present only after 72 h incubation (ARO cell mortality increased of approximately 4 fold over control at 1 microM, 7 fold at 100 microM). When gemcitabine was encapsulated in liposomes, a significant effect was observed by using lower concentrations of the drug (increased cell mortality of 2.4 fold vs. control at 0.3 microM) and earlier exposure time (24 h).

CONCLUSION

These findings show that, in vitro against human thyroid cancer cells, the gemcitabine incorporation within liposomes enhances the drug cytotoxic effect with respect to free gemcitabine, thus suggesting a more effective drug uptake inside the cells. This may allow the use of new formulations with lower dosages (side effect free) for the treatment of anaplastic human thyroid tumours.

Thyroid cancer immuno-therapy with retroviral and adenoviral vectors expressing granulocyte macrophage colony stimulating factor and interleukin-12 in a rat model

BACKGROUND

Introduction of genes encoding immuno-stimulatory cytokine(s) into cancer cells is well known to enhance anti-tumour immunity.

AIM

The present studies were designed to evaluate the therapeutic efficacy of retroviral- and adenoviral-mediated delivery of IL-12 and/or granulocyte macrophage colony-stimulating factor (GM-CSF) genes for thyroid cancer in an immuno-competent rat model.

METHODS

A rat thyroid cancer cell line FRTL-Tc syngeneic to Fisher rat was used.

RESULTS

Expression of these exogenous cytokines did not affect in vitro cell growth. Subcutaneous injection of FRTL-Tc cells retrovirally transduced with IL-12 or GM-CSF genes formed significantly smaller tumours than that of the parental cells, but had little effect on growth of distant tumours, suggesting no vaccine effect. Similarly, injection of the cells infected with adenovirus expressing IL-12 or GM-CSF (AdIL-12 or AdGM-CSF) almost completely abolished tumourigenicity and injection of AdGM-CSF into pre-established tumours significantly inhibited growth of the tumours injected; neither, however, showed a systemic vaccine affect. On the other hand, injection of AdIL-12 into the pre-established tumours significantly inhibited growth of not only the tumours injected but also distant tumours, indicating induction of systemic anti-tumour immunity. Serum IL-12 was detectable only in this approach. There was neither a synergistic or additive effect of these two cytokines.

CONCLUSIONS

Our data demonstrate in a rat thyroid cancer model that only injection of AdIL-12 into the pre-established tumours elicited systemic anti-tumour immunity, but injection of AdGM-CSF or injection of the cells expressing IL-12 or GM-CSF elicited only local effect, indicating that in situdelivery of IL-12 gene with adenovirus appears most efficacious but may still require adjuvant modalities to enhance the anti-tumour effect.

Anaplastic transformation of thyroid cancer: review of clinical, pathologic, and molecular evidence provides new insights into disease biology and future therapy

BACKGROUND

Anaplastic thyroid cancer ranks among the most lethal of all human malignancies. Its rarity and rapidly fatal course have made it a difficult cancer to both study and treat. Unfortunately, there has been little progress in the management and control of this malignancy. Anaplastic transformation, or the intratumoral evolution of anaplastic carcinoma from pre-existing differentiated thyroid cancer, has become a well-accepted process, despite a limited understanding of its underlying mechanisms.

METHODS

It is through review of the literature that an understanding of the aggressive disease biology can be developed. The aim of this review is to evaluate the relevant clinical, pathologic, and molecular studies to develop an insight into the mechanisms that underlie the intratumoral molecular evolution of anaplastic thyroid carcinoma.

RESULTS/CONCLUSION

It is based on an understanding of this process that effective treatments for this aggressive malignancy are currently being developed.

ONYX-015, an E1B gene-defective adenovirus, induces cell death in human anaplastic thyroid carcinoma cell lines

Being one of the most lethal human neoplasms and refractory to such conventional treatment as chemo- and radiotherapy, anaplastic thyroid carcinoma is a prime target for innovative therapy. p53 gene inactivation is a constant feature of this neoplasia. Therefore, we evaluated a therapeutic approach based on an E1B 55-kDa gene-defective adenovirus (ONYX-015) that replicates only in cells with impaired p53 function and leads to cell death. Here we report that the ONYX-015 virus induces cell death in three human thyroid anaplastic carcinoma cell lines (ARO, FRO, and KAT-4). In addition, we found that the growth of xenograft tumors induced in athymic mice by the injection of ARO cells was drastically reduced by ONYX-015 treatment. The ONYX-015 virus worked synergistically with two antineoplastic drugs (doxorubicin and paclitaxel) in inducing ARO and KAT-4 cell death. These results suggest that ONYX-015 may be a valid tool in the treatment of the human thyroid anaplastic carcinoma.