The regulation of proliferation and invasion in differentiated thyroid cancer by growth factors

Invasion and metastasis are the primary cause of death in patients with follicular thyroid cancer (FTC). The thyroid is a micro-economic system in which proliferation and differentiation was supposed to be under the major control of only a single hormone (thyroid stimulating hormone-TSH). It has shown, however, that a complex network of various growth factors regulates growth and invasion of thyroid cancer cells. A growing literature has established the close association between malignant tumor progression and growth regulatory aberrations in cancer cells. Most of these studies have focused on the phenomenon, that advanced and more aggressive tumors or metastases lost the sensitivity to growth inhibitors, such as transforming growth factor beta. These findings highlight two aberrations of growth regulation which may favour progression of malignant disease and acquisition of metastatic competence: (1) Resistance to growth factor inhibitors and (2) growth autonomy of metastatic follicular thyroid cancer cells.

Surgical treatment of parathyroid carcinoma (Review)

Cancer of the parathyroid gland is rare and most patients suffer from hyperparathyroidism (HPT). Therefore it is often difficult to distinguish between benign HPT and malignant disorders. Prognosis as well as therapeutic approaches are still limited. Surgical treatment should be considered the therapy of choice for primary and recurrent manifestation of parathyroid carcinoma. The initial operation includes en-bloc resection of the tumor and the ipsilateral thyroid lobe. Surgery may cure some patients, but is often only palliative and aims to control hypercalcemia. In some patients hypercalcemia may be refractory to repeated surgery and medical treatment can provide short- or middle-term effects.

Follicular thyroid cancer cells: a model of metastatic tumor in vitro (review)

We used a thyroid metastatic tumor model to analyze some of the mechanisms of invasion and metastasis in culture. Chronic TSH stimulation (thyroid stimulating hormone) was associated with enhanced tumor proliferation and aggressiveness. We present a unique metastatic tumor model including three follicular thyroid cancer cell lines using a human primary tumor and two metastases of the same patient. They contain thyroglobulin, have intact thyroid functions and response to TSH. Investigating growth factor sensitivity we found that the amplitude of stimulation or inhibition of invasion was significantly smaller in both metastatic cell lines. Unstimulated cells of the lung metastasis had the highest basal invasive potential, but were only minimally affected by the stimulation of growth factors. In contrast, the parental cell line had the lowest basal invasiveness, but was considerably stimulated by growth factors.

Heterologous desensitization in neoplastic thyroid cells: influence of the phospholipase C signal transduction system on the thyrotropin-adenylate cyclase signal transduction system

Desensitization is defined as a decreased functional response after continuous or repetitive stimulation of a receptor with its agonist. Thyrotropin (TSH) increases cAMP levels in normal and neoplastic thyroid tissue. The tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) activates protein kinase C (PKC). The aim was to determine whether TPA induces heterologous desensitization of the TSH-adenylate cyclase (AC) signal transduction system. Three human thyroid neoplasms in culture for 6 months or longer (one papillary carcinoma, one Hurthle cell carcinoma, one follicular adenoma) were incubated with TSH (10 mU/ml) and TPA (1.6 x 10(-8) M) separately and together for various time periods (from 10 minutes to 24 hours). The mixture was subsequently incubated for 30 minutes with TSH. TPA alone had no effect on cAMP levels, but co-incubation of TPA and TSH caused a significant reduction in cAMP response when compared to the cAMP response that resulted after stimulation with only TSH (p < 0.001). cAMP levels in response to TSH decreased by 31%, 44%, and 57% after preincubation with TSH for 10 minutes, 4 hours, and 24 hours, respectively (p < 0.01; ANOVA). Co-incubation of cells with TPA and staurosporine (10 ng/ml), a PKC inhibitor, prevented the effect of TPA on desensitization at 10 minutes and blunted the effect at 4 hours. This is the first demonstration in human neoplastic thyroid cells that TPA induced heterologous desensitization of the cAMP response to TSH. This TPA-induced effect appears to involve PKC activation, as it can be blocked by staurosporine.

[Transfection of follicular thyroid gland carcinoma cells with human TSH receptor changes growth, invasion and adhesion]

TSH is the classic stimulator of thyroid cell function. Clinically, treatment with thyroxin to suppress TSH decreased the risk of thyroid cancer recurrence and improved patient survival. This study analyzed the effect of stably transfected human TSH receptor cDNA in an established model of metastatic follicular thyroid cancer cells (FC) compared to wild type FTC. Wild type FTC lack TSH receptors and do not depend on TSH for growth. However, they contain thyroglobulin, have intact thyroid functions and response to TSH. We tested growth, invasion, and adhesion of transfected tumor cells (FTC-TSHr) compared to parental cells. All transfected FTC-TSHr expressed TSHr mRNA. Compared to wild type cells invasion and growth of TSHr-transfected FTC were significantly inhibited (p < 0.001). All FTC adhered best to collagen IV and fibronectin. Compared to parental cells adhesion of unstimulated FTC-TSHr was significantly enhanced (p < 0.001). These in vitro data underline the important role of the human TSH receptor as the main regulator of thyroid growth and functions.

The role of growth factors in proliferation and invasion of thyroid cancer

A growing literature has established the close association between tumor progression and growth regulatory aberrations in cancer cells. Most studies have focused on the phenomenon, that advanced tumors or metastases have lost the sensitivity to growth inhibitors. Metastasis are the primary cause of death in patients with differentiated thyroid cancer. Proliferation and differentiation of the thyroid was supposed to be under the major control of only a single hormone (thyroid stimulating hormone). However, we and others have shown that a complex network of various growth factors regulates growth and invasion of thyroid cancer cells. Our findings highlight two aberrations of growth regulation which may favour progression of malignancy and acquisition of metastatic competence: i) resistence to growth factor inhibitors and ii) growth autonomy of metastatic thyroid cancer cells.

Entrapment of the popliteal artery and its surgical management in a 20-year period

BACKGROUND

This study was a retrospective review of 19 patients with popliteal artery entrapment syndrome (PAES) treated in a 20-year interval.

METHODS

The Heidelberg classification of PAES was used, which differentiates three categories of entrapment: in type I the popliteal artery has an atypical course, in type II the muscular insertion is atypical, and in type III both conditions are present. Besides decompression of the popliteal artery the commonest operative reconstruction used was resection of the atherosclerotic part of the artery and autologous vein interposition grafting (n = 12). Local thromboendarterectomy was done in seven cases, six with a vein patch angioplasty repair.

RESULTS

Follow-up ranged from 6 months to 20 years (mean 9.5 years). There was no limb loss. The rate of complications was lowest after primary venous interposition (two of 12) compared with five of 11 when venous interposition was not used (P < 0.01).

CONCLUSION

Autologous saphenous vein interposition grafting seems to be the best treatment for PAES.

Somatostatin analog octreotide inhibits the growth of differentiated thyroid cancer cells in vitro, but not in vivo

Somatostatin and its analogs are antiproliferative in a wide range of normal and neoplastic tissues. In this study we investigated the effect of octreotide (SMS 201-995) on the invasion and growth of three follicular thyroid cancer (FTC) cell lines from one patient in vitro and in vivo. FTC133 was established from the primary tumor, FTC236 from a cervical lymph node metastasis, and FTC238 from a lung metastasis. Invasion was the ability of tumor cells to penetrate 8-microns pore polycarbonate membranes coated with Matrigel. Invasion and proliferation were analyzed using the MTT assay. For in vivo experiments, athymic nude mice were sc inoculated with 500,000 calls of FTC133. The animals were treated twice daily with octreotide sc (100-300 micrograms/kg). RIA studies yielded dose-dependent high plasma levels of octreotide (3.43-6.5 ng/mL). Octreotide had a biphasic effect, enhancing growth at low concentrations (1-10 nmol/mL) and inhibiting it at high concentrations (100 nmol to 1 mumol/mL). Octreotide had also a dose-dependent biphasic effect on the invasion of FTC, inhibiting the invasion of all follicular thyroid cancer lines at high concentrations. However, it affected invasion less than growth. Octreotide (10 nmol/mL) stimulated the invasion of FTC133 by 13%, whereas stimulation was lower in both FTC metastases (FTC236, 6%; FTC238, 7%; P < 0.01). At higher concentrations (100 nmol to 1 mumol/mL), octreotide inhibited invasion of FTC133 by 17% (FTC236, 15%; FTC238, 17%; P < 0.01). During a 3-week treatment period, octreotide had no antiproliferative effect on the growth of FTC133 cells in nude mice. In conclusion, octreotide at low concentrations stimulates and at high concentrations inhibits the growth and invasion of follicular thyroid cancer cells in culture. However, it has no effect on the growth of FTC cells in animal experiments. Thus, the value of octreotide as an antitumoral agent in follicular thyroid cancer must be critically questioned.

Tamoxifen antagonizes proliferation and invasion of estrogen receptor-negative metastatic follicular thyroid cancer cells via protein kinase C

Tamoxifen inhibits invasion and growth of estrogen-receptor negative follicular thyroid cancer (FTC) cells in vitro and in vivo. To study the mechanisms involved, we documented the effects of tamoxifen and staurosporine on three metastatic FTC-cell lines. TPA (10 ng/ml) enhanced invasion and growth of FTC by 15% (P < 0.02). Tamoxifen (1.5 micromol/l) inhibited invasion of FTC133 by 36% (FTC236 30%; FTC238 32%; P < 0.01). TPA reversed the tamoxifen-mediated inhibition of invasion by 35% in FTC133 and 30% in FTC238 (P < 0.02). Staurosporine (10 ng/ml) inhibited invasion and growth of all FTC. At 0.1-1 ng/ml it enhanced the inhibitory effects of tamoxifen, but did not further inhibit invasion or growth at higher concentrations. We conclude that the antiproliferative and antiinvasive effects of tamoxifen on follicular thyroid cancer cells are at least partly mediated by an inhibition of protein kinase C.

Intraoperative tumour classification in papillary thyroid cancer--a diagnostic dilemma

The objective of the study was to assess surgical strategy of papillary carcinoma of the thyroid based on residual tumour findings after completion thyroidectomy. We investigated the accuracy of intraoperative tumour classification in papillary thyroid cancers (PTC) and its effect on intraoperative decision-making. In a 34-year period, we performed 182 total thyroidectomies for PTC, 69 of which were completion thyroidectomies. The indications for completion thyroidectomy were (1) inaccurate assessment of the size of solitary tumours (n = 28), (2) unilateral (n = 23) and (3) bilateral multicentricity (n = 18). Fifteen patients had residual cancers (22%), which were significantly correlated with the extent of the first procedure. After initial lobectomy, residual tumours were present in 54% of patients, compared to only 3% after initial lobectomy, isthmusectomy and contralateral subtotal lobectomy. We favour lobectomy, isthmusectomy and contralateral subtotal lobectomy in patients with papillary thyroid cancers smaller than 1.5 cm in diameter and a total thyroidectomy in all other cases.

Biphasic effects of thyrotropin on invasion and growth of papillary and follicular thyroid cancer in vitro

The rationale for TSH suppression in the treatment of follicular thyroid cancer (FTC) and papillary thyroid cancer (PTC) is to inhibit tumor growth, prevent recurrent disease, and eventually prolong survival. We analyzed the effects of TSH on invasion and growth of 3 FTC cell lines from 1 patient (FTC133, primary; FTC236, lymph node; FTC238, lung metastasis) and 2 PTC cell lines (PTC-UC1, PTC-UC3). Cell growth and invasion through an 8-micron pore polycarbonate membrane coated with Matrigel were measured using the MTT assay. The dose-response to TSH was biphasic, stimulating invasion and growth of FTC and PTC at low concentrations (0.1-10 mU/mL), and inhibiting them at high concentrations (100 mU/mL). Interestingly, the metastatic FTC cell lines had higher basal invasion, but were less responsive to TSH than the primary tumor. TSH (1 mU/mL) stimulated invasion of FTC133 by 21%, FTC236 by 8%, and FTC238 by 8% (p < 0.01). At 100 mU/mL, TSH inhibited invasion of FTC133 by 21%, compared to 11% in FTC236 and 12% in FTC238. Also, TSH dose-dependently influenced proliferation of follicular thyroid cancer cells. At low concentrations it stimulated growth of FTC133 (20%) and inhibited it at high concentrations (23%; p < 0.01). Again, the amplitude of TSH effects was significantly smaller in the cell lines from metastatic tumors. TSH affected invasion and growth of PTC-UC1 and PTC-UC3 also biphasically. These results show that TSH may act as a mitogenic and antimitogenic growth factor for invasion and proliferation of well-differentiated thyroid cancer cells in vitro.

Tamoxifen inhibits growth, migration, and invasion of human follicular and papillary thyroid cancer cells in vitro and in vivo

Prognosis of differentiated thyroid cancer is best in young women. It has been proposed that sex steroids protect premenopausal women from aggressive thyroid malignancies. Some thyroid tissues have estrogen receptors, and estrogen stimulates human thyroid cells. Tamoxifen is thought to exert its antiproliferative effects mainly by blocking estrogen stimulation. However, recently, mechanisms independent of estrogen interactions were found to be important for the favorable effect. We investigated the effect of tamoxifen on the growth, migration, and invasion in three follicular thyroid cancer cell lines (FTC133, primary; FTC236, lymph node; and FTC238, lung metastasis) from one patient and two papillary lines (PTC-UC1 and PTC-UC3). Growth was measured by dimethylthiazol-diphenyltetrazolium bromide assays, and migration was determined by the ability of cells to penetrate 8-microns pore membranes, which were covered by Matrigel for invasion assays. For in vivo experiments, we used xenografts of FTC133 in nude mice. Tamoxifen (1.5 mumol/L) inhibited the growth of all thyroid cancer cell lines (FTC133, 59%; FTC236, 42%; FTC238, 46%; P < 0.01). This effect was less pronounced in PTC-UC1 (25%) and PTC-UC3 (19%; P < 0.006) cell lines. Tamoxifen also inhibited migration and invasion of FTC more than PTC. Invasion of FTC133 was inhibited by 36% (P < 0.01), FTC236 by 30%, and FTC238 by 32%. Immunohistochemistry showed no estrogen receptors in any cell line. Also, estradiol had no significant effect on the growth, migration, or invasion of FTC or PTC. Tamoxifen treatment inhibited the growth of FTC133 xenografts in nude mice by 52% compared to that in placebo-treated controls (P < 0.002). In conclusion, tamoxifen inhibited the growth, migration, and invasion of differentiated thyroid cancer cells in vitro and in vivo. This was not reversed by estrogen. Tamoxifen acts independently of estrogen interactions and may be useful as an adjuvant treatment for some differentiated human thyroid malignancies.

The value of preoperative lytic therapy in limb-threatening acute ischemia from popliteal artery aneurysm

In a retrospective study, we analyzed our experiences in 24 patients with acute ischemia from popliteal artery aneurysms over a period of 27 years and evaluated the value of a preoperative lytic therapy as an adjunct to surgical revascularization, compared to surgery alone. Preoperative urokinase therapy revealed a satisfactory improvement of the runoff in all cases. Follow-up angiography showed complete lysis in 6 and incomplete lysis in 3 of 9 patients. In contrast, in patients treated by surgery alone, postoperative angiography showed residual clots in all cases. The overall amputation rate was 25% (6/24) in 24 popliteal aneurysms with acute ischemia, including four patients with primary amputation for irreversible gangrene. Bypass grafting alone resulted in an early amputation rate of 9% (1/11) and occlusive complications of 45% (5/11) compared to no limb loss and no bypass complication in patients who underwent combined surgery and preoperative lysis (0/9). Our results underline the value of preoperative lytic therapy as an important factor in the management of acute ischemia in popliteal artery aneurysms.

Epidermal growth factor enhances proliferation, migration, and invasion of follicular and papillary thyroid cancer in vitro and in vivo

The prognosis of patients with follicular (FTC) and papillary (PTC) thyroid cancer depends on age and the size and extent of the tumor. Differentiated thyroid cancers bind more epidermal growth factor (EGF) than normal thyroid tissue, but the role of EGF in the proliferation and invasion of thyroid cancer is unknown. We investigated the effects of EGF on growth, migration, and invasion in a follicular thyroid cancer that metastasized to cervical lymph nodes and the lung (FTC 133, primary; FTC 236, lymph node; and FTC 238, lung metastasis) and in a papillary thyroid cancer (PTC-UC3). As measured by the formazan method (dimethylthiazol-diphenyltetrazolium bromide), EGF caused a dose- and time-dependent increase in the growth of FTC 133 and PTC-UC3 by 25%, but its stimulatory effect on growth of the metastatic FTC subclones was smaller (FTC 236, 14%; FTC 238, 8%; P < 0.001). EGF also enhanced the ability of all cell lines to migrate (through 8-microns pore membranes without Matrigel) or invade (membranes with Matrigel). Migration of FTC 133 was enhanced from 86% migrated tumor cells to 95% after 72 h (P < 0.02). Again, stimulation by EGF was lower in FTC 236 and FTC 238. EGF increased migration in PTC-UC3 from 49% to 58%. EGF stimulated invasion of FTC 133 from 17.5% to 24.9%. In the absence of EGF, FTC 238 was the most invasive tumor, but, again, the EGF stimulatory effect was less pronounced than in the primary tumor. EGF stimulated the invasion of PTC-UC3 from 10.9% to 14.3% (P < 0.03). EGF also stimulated the growth of thyroid cancer xenografts in nude mice. Although all FTC cell lines were 100% tumorigenic in nude mice, PTC-UC3 was less tumorigenic. However, after sc inoculation of EGF-pretreated tumor cells, 7 of 10 animals developed tumors (mean size, 2.3 cm3) compared to 2 of 10 animals (mean size, 1.4 cm3) in the control group (P < 0.02). In summary, EGF stimulates the growth and invasion of differentiated thyroid cancer cells in culture and in nude mice. Escape from growth factor control, such as in FTC 236 and FTC 238, may be an important step in the development of metastatic thyroid cancer.

Aberrations of growth factor control in metastatic follicular thyroid cancer in vitro

The aggressiveness of follicular thyroid cancer (FTC) varies widely, and metastasis is the primary cause of death. Uncontrolled proliferation of cancer cells may be associated with loss of growth factor control. We investigated the effects of stimulating (epidermal growth factor [EGF]; thyreotropin [TSH] in low concentrations) and inhibiting growth factors (transforming growth factor beta 1 [TGF beta 1]; TSH in high concentrations) on invasion and growth of FTC cell lines from the thyroid tumor (FTC133) and from the lymph node (FTC236) and lung (FTC238) metastases of the same patient. Invasion-penetration through an 8 microns pore membrane, covered by Matrigel (basement membrane)-and growth were measured using the MTT-method. EGF (10 ng/ml) and TSH in low concentrations (1 mU/ml) stimulated invasion and growth of all FTC cell lines, but the amplitude of stimulation differed significantly. The parental cell line FTC133 was considerably more responsive to growth factor stimulation than the metastatic clones. Invasion of FTC133 was enhanced by 42% (EGF; p < 0.02) and 21% (TSH; p < 0.01), invasion of FTC236 by 8% (EGF; p < 0.02) and 8% (TSH; p < 0.01), and invasion of FTC238 by 9% (EGF; p < 0.02) and 8% (TSH; p < 0.01). Conversely, invasion and growth of FTC133 were significantly more inhibited by TGF beta 1 (10 ng/ml) and supraphysiologic concentrations of TSH (100 mU/ml) than the cell lines from the lymph node and lung metastases. At day 7, invasion of FTC133 was inhibited by 32% (TGF beta 1; p < 0.02) and 21% (TSH; p < 0.01), invasion of FTC236 by 18% (TGF beta 1; p < 0.02) and 11% (TSH; p < 0.01), and invasion of FTC238 by 16% (TGF beta 1; p < 0.02) and 12% (TSH; p < 0.01). Moreover, we analyzed growth factor independence in minimally supplemented or unsupplemented medium. Growth, but no invasion was evident when cells were cultured completely unsupplemented over 7 days. These results suggest that metastatic FTCs may have developed by escaping from the normal control of TSH and other growth factors.

Management of patients with differentiated thyroid cancer who have positive serum thyroglobulin levels and negative radioiodine scans

Most current evidence suggests that patients with papillary or follicular thyroid cancer after total thyroidectomy who are Tg positive (Tg > or = 10 ng/mL) and radioactive iodine scan negative warrant treatment with 100 mCi of 131I with a follow up scan and Tg determination. If isolated focal metastatic deposits are present they should be resected before treatment with radioiodine. Although some physicians might recommend radioiodine treatment only for high risk patients, we would recommend it for all patients with elevated serum Tg levels that increase after TSH stimulation, or until further information becomes available to support a different approach.

Thyrotropin stimulates invasion and growth of follicular thyroid cancer cells via PKC- rather than PKA-activation

The signal transduction of TSH in invasion and growth of FTC 133, a human follicular thyroid cancer cell line, was investigated. TSH (0.01-1 mIU/ml) stimulated invasion of FTC 133 by 21% and growth by 20% of basal. Cyclic AMP-stimulators and inhibitors had no effect at any concentration. The PKC-agonist TPA enhanced invasion and growth by 15%, whereas staurosporine, a PKC-antagonist, inhibited them by 32% and 60%, respectively. The latter also reversed TSH stimulation. EGF enhanced invasion (42%) and growth of FTC 133 (25%). Staurosporine did not reverse EGF stimulation. The tyrosine kinase antagonist genistein reversed EGF, but not TSH stimulation. Pertussis toxin inhibited invasion (18%) and growth (22%). Cholera toxin was less inhibitive. We demonstrated for the first time, that TSH stimulates invasion and growth of human thyroid cancer cells in vitro by PKC- rather than PKA-stimulation.