Sissy M. Jhiang

Long-term impact of initial surgical and medical therapy on papillary and follicular thyroid cancer

PURPOSE To determine the long-term impact of medical and surgical treatment of well differentiated papillary and follicular thyroid cancer. METHODS Patients with papillary and follicular cancer (n = 1,355) treated either in U.S. Air Force or Ohio State University hospitals over the past 40 years were prospectively followed by questionnaire or personal examination to determine treatment outcomes. Outcomes were analyzed by Kaplan-Meier survival curves and Cox proportional-hazard regression model. RESULTS Median follow-up was 15.7 years; 42% (568) of the patients were followed for 20 years and 14% (185) for 30 years. After 30 years, the survival rate was 76%, the recurrence rate was 30%, and the cancer death rate was 8%. Recurrences were most frequent at the extremes of age (< 20 and > 59 years). Cancer mortality rates were lowest in patients younger than 40 years and increased with each subsequent decade of life. Thirty-year cancer mortality rates were greatest in follicular cancer patients, who were more likely to have adverse prognostic factors: older age, larger tumors, more mediastinal node involvement, and distant metastases. When patients with distant metastases at diagnosis were excluded, follicular and papillary cancer mortality rates were similar (10% versus 6%, P not significant [NS]). In a Cox regression model that excluded patients who presented with distant metastases, the likelihood of cancer death was (1) increased by age > or = 40 years, tumor size > or = 1.5 cm, local tumor invasion, regional lymph-node metastases, and delay in therapy > or = 12 months; (2) reduced by female sex, surgery more extensive than lobectomy, and 131I plus thyroid hormone therapy; and (3) unaffected by tumor histologic type. Following 131I therapy given only to ablate normal thyroid gland remnants, the recurrence rate was less than one third the rate after thyroid hormone therapy alone (P < 0.001). No patient treated in this way with 131I has died of thyroid cancer. Low 131I doses (29 to 50 mCi) were as effective as high doses (51 to 200 mCi) in controlling tumor recurrence (7% versus 9%, P = NS). Following 131I therapy, whether given for thyroid remnant ablation or cancer therapy, recurrence and the likelihood of cancer death were reduced by at least half, despite the existence of more adverse prognostic factors in patients given 131I. At 30 years, the cumulative cancer mortality rate following 131I therapy, regardless of the reason for its use, was one third that in patients not so treated (P = 0.03). CONCLUSION Over the long term, for tumors > or = 1.5 cm that are not initially metastatic to distant sites, near-total thyroidectomy followed by 131I plus thyroid hormone therapy confers a distinct outcome advantage. This therapy reduces tumor recurrence and mortality sufficiently to offset the augmented risks incurred by delayed therapy, age > or = 40 at the time of diagnosis, and tumors that are much larger than 1.5 cm, multicentric, locally invasive, or regionally metastatic.

The RET proto-oncogene in human cancers.

The activation of the RET proto-oncogene contributes to the development of human cancers in two different ways. Somatic rearrangements of RET with a variety of activating genes, which contribute to unscheduled expression and constitutive dimerization of the chimeric RET/PTC oncoproteins in thyroid follicular cells, are frequently found in radiation-induced papillary thyroid carcinomas. Germ-line mutations, mainly point mutations, that lead to constitutive activation of RET tyrosine kinase activity are responsible for the development of the inherited cancer syndrome, multiple endocrine neoplasia type 2. There appears to be a correlation between specific types of RET mutation and clinical phenotypes of the cancers involved. The biological effects and the signaling pathways induced by different forms of RET activation have been investigated in a variety of cultured cells as well as in genetically engineered animal models. The identification of RET mutations in most MEN 2 families (95%) has translated into improved care for MEN 2 patients. However, further investigation of the signaling pathways contributing to tumorigenesis in relevant tissues will eventually help us to develop novel strategies to prevent or to treat human papillary thyroid carcinomas, MEN 2 disease, as well as the sporadic cancers relevant to MEN 2 disease.

Papillary and Follicular Thyroid Carcinomas Show Distinctly Different Microarray Expression Profiles and Can Be Distinguished by a Minimum of Five Genes

PURPOSE We have previously conducted independent microarray expression analyses of the two most common types of nonmedullary thyroid carcinoma, namely papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC). In this study, we sought to combine our data sets to shed light on the similarities and differences between these tumor types. MATERIALS AND METHODS Microarray data from six PTCs, nine FTCs, and 13 normal thyroid samples were normalized to remove interlaboratory variability and then analyzed by unsupervised clustering, t test, and by comparison of absolute and change calls. Expression changes in four genes not previously implicated in thyroid carcinogenesis were verified by reverse transcriptase polymerase chain reaction on these same samples, together with eight additional FTC tumors. RESULTS PTCs showed two distinct groups of genes that were either over- or underexpressed compared with normal thyroid, whereas the predominant changes in FTCs were of decreased expression. Five genes could collectively distinguish the two tumor types. PTCs showed overexpression of CITED1, claudin-10 (CLDN10), and insulin-like growth factor binding protein 6 (IGFBP6) but showed no change in expression of caveolin-1 (CAV1) or -2 (CAV2); conversely, FTCs did not express CLDN10 and had decreased expression of IGFBP6 and/or CAV1 and CAV2. CONCLUSION PTC and FTC show distinctive microarray expression profiles, suggesting that either they have different molecular origins or they diverge distinctly from a common origin. Furthermore, if verified in a larger series of tumors, these genes could, in combination with known tumor-specific chromosome translocations, form the basis of a valuable diagnostic tool.

Cloning of the human taurine transporter and characterization of taurine uptake in thyroid cells

A cDNA clone encoding a taurine transporter, designated HTAU, has been isolated from human thyroid. It contains an open reading frame encoding a protein of 619 amino acids with a calculated molecular weight of 69,675 Da. The predicted amino acid sequence of HTAU is highly homologous to those of dog kidney and rat brain. The HTAU mRNA was detectable in various human tissues examined. Transient expression of HTAU in COS‐7 cells conferred a higher taurine uptake. The taurine uptake in FRTL‐5 cells appears to be regulated by thyrotropin through cAMP. Finally, a higher taurine uptake may be associated with a higher proliferation rate in some cultured cell lines.

Expression and activity of human Na + /I − symporter in human glioma cells by adenovirus-mediated gene delivery

Radioiodide concentrating activity in the thyroid, mediated by human Na+/I− symporter (hNIS), provides a mechanism for effective radioiodide treatment for patients who have invasive, recurrent, and metastatic thyroid cancers after total thyroidectomy. In an attempt to develop hNIS gene transfer for radioiodide therapy for patients with brain tumors, we have constructed recombinant adenoviruses, rAd-CMV-hNIS9 and rAd-CMV-FLhNIS, to express exogenous hNIS in U1240 and U1240Tag human glioma cells. U1240Tag differs from U1240 glioma cells in that it expresses the SV40 large T antigen oncoprotein. In both U1240 and U1240Tag cells, radioiodide uptake (RAIU) activity in the cells infected with rAd-CMV-hNIS9 or rAd-CMV-FLhNIS increases as the adenoviral MOI increases. The protein expression profile of hNIS in infected cells is generally in agreement with their RAIU activity profile. Although the expressed hNIS9 protein appeared to have a shorter half-life than FLhNIS, hNIS9 expression could be maintained by multiple infections in these cells. In addition, we show that hNIS can be expressed and function in a xenografted human glioma by intratumoral injection of rAd-CMV-hNIS9.

In vivo imaging and radioiodine therapy following sodium iodide symporter gene transfer in animal model of intracerebral gliomas

Radioactive iodide uptake (RAIU) in thyroid follicular epithelial cells, mediated by the sodium iodide symporter (NIS), is the first rate-limiting step in iodide accumulation which provides a mechanism for effective radioiodide treatment for patients with thyroid cancer. We hypothesize that NIS gene transfer to non-thyroid tumor cells will enhance intracellular radioiodide accumulation and result in better tumor control. Here, we performed non-invasive tumor imaging and 131I therapy studies using rats bearing intracerebral F98 gliomas that have been retrovirally transduced with human NIS. Our results show that: (1) NIS is expressed in the intracerebral F98/NIS gliomas; (2) F98/NIS gliomas can be imaged by 99mTcO4 (whose uptake is also mediated by NIS) and 123I scintigraphy; (3) significant amounts of radioiodide were retained in the tumors at 24 h after 123I injection; (4) RAIU and NIS expression in the thyroid gland can be reduced by feeding a thyroxine-supplemented diet; and (5) survival time was increased in rats bearing F98/hNIS tumors by 131I treatment. These studies warrant further investigating tumor imaging and therapeutic strategies based on NIS gene transfer followed by radioiodide administration in a variety of human cancers.

Loss of p53 Promotes Anaplasia and Local Invasion in ret/PTC1-Induced Thyroid Carcinomas

Papillary thyroid carcinomas in humans are associated with the ret/PTC oncogene and, following loss of p53 function, may progress to anaplastic carcinomas. Mice with thyroid-targeted expression of ret/PTC1 developed papillary thyroid carcinomas that were minimally invasive and did not metastasize. These mice were crossed with p53-/- mice to investigate whether loss of p53 would promote anaplasia and metastasis of ret/PTC1-induced thyroid tumors. The majority of p53-/- mice died or were euthanized by 17 weeks of age due to the development of thymic lymphomas, soft tissue sarcomas, and testicular teratomas. All ret/PTC1 mice developed thyroid carcinomas, but tumors in p53-/- mice were more anaplastic, larger in diameter, more invasive, and had a higher mitotic index than tumors in p53+/+ and p53+/- mice. Thyroid tumors did not metastasize in any of the experimental p53+/+ and p53+/- mice </=28 weeks of age or p53-/- mice </= 17 weeks of age; however, an older (170-day-old) male p53-/- mouse used to maintain the colony developed anaplastic thyroid carcinoma with liver metastases. These findings demonstrate that the lack of functional p53 in ret/PTC1 mice promotes anaplasia and invasiveness of thyroid carcinomas.

Sodium Iodide Symporter in Health and Disease

Radioiodine-concentrating activity in thyroid tissues has allowed the use of radioiodine as a diagnostic and therapeutic agent for patients with thyroid disorders such as well-differentiated thyroid cancer. However, some extrathyroidal tissues also take up radioiodine, contributing to unwanted side effects of radioiodine therapy. Now that the molecule that mediates radioiodine uptake, the sodium iodide symporter (NIS), has been cloned and characterized, it may be possible to develop novel strategies to differentially modulate NIS expression and/or activity, enhancing it in target tissues and impeding it in others. In addition to restoring NIS expression/activity to ensure sufficient radioiodine uptake for the diagnosis and treatment of advanced thyroid cancers, we envision that it may be possible to selectively increase or confer NIS expression/activity in tumors of nonthyroidal tissues to facilitate the use of radioiodine in their diagnosis and treatment. We also consider the molecular basis of thyroid and nonthyroid disorders that may be complicated by NIS deregulation. Finally, we explore the use of NIS as an imaging reporter gene to monitor the expression profile of the transgene in transgenic mouse animal models and in patients undergoing gene therapy clinical trials.

GENIS: Gene Expression of Sodium Iodide Symporter for Noninvasive Imaging of Gene Therapy Vectors and Quantification of Gene Expression in Vivo

With the goal of optimizing adenovirus-mediated suicide gene therapy for prostate cancer, we have developed a method based on the human sodium iodide symporter (hNIS) that allows for noninvasive monitoring of adenoviral vectors and quantification of gene expression magnitude and volume within the prostate. A replication-competent adenovirus (Ad5-yCD/mutTK(SR39)rep-hNIS) coexpressing a therapeutic yeast cytosine deaminase (yCD)/mutant herpes simplex virus thymidine kinase (mutTK(SR39)) fusion gene and the hNIS gene was developed. Ad5-yCD/mutTK(SR39)rep-hNIS and a replication-defective hNIS adenovirus (rAd-CMV-FLhNIS) were injected into contralateral lobes of the dog prostate and hNIS activity was monitored in live animals following administration of Na(99m)TcO(4) using gamma camera scintigraphy. Despite the close proximity of the urinary bladder, (99m)TcO(4)(-) uptake was readily detected in the prostate using viral dose levels (10(10) to 10(12) viral particles) that have been safely administered to humans. Due to its rapid clearance and short physical half-life (6 h), it was possible to obtain daily measurements of (99m)TcO(4)(-) uptake in vivo, allowing for dynamic monitoring of reporter gene expression within the prostate as well as biodistribution throughout the body. High-resolution autoradiography of prostate sections coupled with 3D reconstruction of gene expression demonstrated that the magnitude and volume of gene expression could be quantified with submillimeter resolution. Implementation of the GENIS (gene expression of Na/I symporter) technology in the clinic will facilitate optimization of future human gene therapy trials.

Efficient Delivery of Cyclic Peptides into Mammalian Cells with Short Sequence Motifs

Cyclic peptides hold great potential as therapeutic agents and research tools, but their broad application has been limited by poor membrane permeability. Here, we report a potentially general approach for intracellular delivery of cyclic peptides. Short peptide motifs rich in arginine and hydrophobic residues (e.g., FΦRRRR, where Φ is l-2-naphthylalanine), when embedded into small- to medium-sized cyclic peptides (7-13 amino acids), bound to the plasma membrane of mammalian cultured cells and were subsequently internalized by the cells. Confocal microscopy and a newly developed peptide internalization assay demonstrated that cyclic peptides containing these transporter motifs were translocated into the cytoplasm and nucleus at efficiencies 2-5-fold higher than that of nonaarginine (R(9)). Furthermore, incorporation of the FΦRRRR motif into a cyclic peptide containing a phosphocoumaryl aminopropionic acid (pCAP) residue generated a cell permeable, fluorogenic probe for detecting intracellular protein tyrosine phosphatase activities.