Improved in vivo antitumor effect of a daunorubicin - GnRH-III bioconjugate modified by apoptosis inducing agent butyric acid on colorectal carcinoma bearing mice.

Compared to classical chemotherapy, peptide-based drug targeting is a promising therapeutic approach for cancer, which can provide increased selectivity and decreased side effects to anticancer drugs. Among various homing devices, gonadotropin-releasing hormone-III (GnRH-III) peptide represents a suitable targeting moiety, in particular in the treatment of hormone independent tumors that highly express GnRH receptors (e.g. colon carcinoma). We have previously shown that GnRH-III[(4)Lys(Ac),(8)Lys(Dau = Aoa)] bioconjugate, in which daunorubicin was attached via oxime linkage to the (8)Lys of a GnRH-III derivative, exerted significant in vivo antitumor effect on subcutaneously developed HT-29 colon tumor. In contrast, results of the study reported here indicated that this compound was not active on an orthotopically developed tumor. However, if Lys in position 4 was acylated with butyric acid instead of acetic acid, the resulting bioconjugate GnRH-III[(4)Lys(Bu),(8)Lys(Dau = Aoa)] had significant tumor growth inhibitory effect. Furthermore, it prevented tumor neovascularization, without detectable side effects. Nevertheless, the development of metastases could not be inhibited by the bioconjugate; therefore, its application in combination with a metastasis preventive agent might be necessary in order to achieve complete tumor remission. In spite of this result, the treatment with GnRH-III[(4)Lys(Bu),(8)Lys(Dau = Aoa)] bioconjugate proved to have significant benefits over the administration of free daunorubicin, which was used at the maximum tolerated dose.

[Studying the tumor growth inhibitory effect of modified GnRH-III-anthracycline bioconjugates in subcutaneous vs. orthotopic models in vivo]. / Módosított GnRH-III-antraciklin biokonjugátumok daganatnövekedést gátló hatásának tanulmányozása in vivo szubkután vs. ortotopikus rendszerekben.

Targeted tumor therapy is a perspective procedure to specifically destroy the cancer tissues with eliminating or at least decreasing the side effects of anticancer drugs. For this purpose the drug molecule is attached to a targeting moiety (e.g. peptide hormones) that recognizes tumor specific or overexpressed receptors on cancer cells. The in vitro cytostatic or cytotoxic assays do not give proper information whether the tumor growth inhibitory effect of the conjugate is better than the activity of the free drug. Only in vivo studies are adequate to answer this question. However, the selection of the appropriate tumor model is important to eliminate the false positive results. In our studies a gonadotropin-releasing hormone analog (GnRH-III) was applied as targeting moiety in drug conjugates. The in vivo antitumor activity of these conjugates was investigated on mice bearing subcutaneously or orthotopically szigdeveloped tumors. The subcutaneously implanted tumor model which is isolated from its surroundings may provide false results in tumor growth inhibition. In contrast, the orthotopically developed tumor is a better model representing appropriate anatomical and clinical status of cancer. Therefore, the orthotopical colon cancer developed in our laboratory is a suitable model for the study of the antitumor activity of the conjugates prepared for targeted tumor therapy.

Serum estrone concentration, estrone sulfate/estrone ratio and BMI are associated with human epidermal growth factor receptor 2 and progesterone receptor status in postmenopausal primary breast cancer patients suffering invasive ductal carcinoma.

BACKGROUND: We investigated in postmenopausal women with primary breast cancer prior to surgical intervention whether, serum levels of different steroid hormones and hormonal precursors associated with tumor tissue estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status. METHODS: We enrolled 1,042 patients suffering invasive ductal carcinoma undergoing surgical resection in the National Institute of Oncology, Hungary between 2003 and 2011. Serum parameters were measured by RIA/IRMA assays; tumor tissue ER, PR and HER2 status was assessed histologically. Patients were classified according to tumor receptor status. Case-case analysis subjects were categorized into four subgroups based on serum hormone concentrations in ER, PR and HER2 receptor-negative cases, respectively. RESULTS: Serum estrone sulfate and dehydroepiandrosterone sulfate levels correlated with each other and also with serum estrone and estradiol levels. According to case-case study the odds ratios in the highest quartile were 1.517 (p = 0.0305, Ptrend = 0.0394) for androstenedione, 1.495 (p = 0.0317, Ptrend < 0.0105) for estrone and 0.654 (p = 0.0273, Ptrend < 0.0151) for estrone sulfate/estrone ratio in PR+ vs. PR- tumors. Regarding HER2 status (HER2+ vs. HER2-), the odds ratios for estrone, estrone sulfate and estrone sulfate/estrone ratio were 0.530 (p = 0.0234, Ptrend = 0.0595), 2.438 (p = 0.0042, Ptrend < 0.0066) and 3.118 (p = 0.0001, Ptrend < 0.0001) in the highest quartile, respectively. Of note significantly increased BMI associates with PR+ and ER +/PR+ status while significantly decreased BMI was observed in HER2+ cases. CONCLUSIONS: Taken together, measurement of serum estrone and estrone sulfate concentrations prior to surgical intervention might support the individualization of regime in postmenopausal primary breast cancer patients.

In-vivo antitumour effect of daunorubicin-GnRH-III derivative conjugates on colon carcinoma-bearing mice.

Targeted cancer chemotherapy is a novel approach developed for the specific delivery of anticancer drugs. Tumour targeting can be achieved by combining a chemotherapeutic agent with a targeting moiety that recognizes tumour-specific or highly expressed receptors on cancer cells. We used the gonadotropin-releasing hormone-III (GnRH-III) as a targeting moiety to which the chemotherapeutic agent daunorubicin (Dau) was attached through an oxime bond either directly or by inserting a GFLG tetrapeptide spacer. The in-vivo toxicity of Dau-GnRH-III derivative conjugates was evaluated on healthy BDF-1 female mice, and their tumour growth inhibitory effect was determined on C26 murine and HT-29 human colon carcinoma-bearing mice. Both oxime bond-containing conjugates were well tolerated and exerted significant antitumour activity on C26 colon carcinoma-bearing mice at a dose of 30 mg Dau content in conjugate/kg body weight. Furthermore, the conjugates inhibited the tumour growth more than the free drug at a dose that was still not toxic. Similar tumour growth inhibitory effects were obtained on HT-29 human colon carcinoma-bearing mice using three treatments with 15 mg Dau content in conjugate/kg. The tumour growth inhibitions according to the tumour volume and the tumour weight were 44/41% and 58/50%, respectively. Considering the results, both of the investigated Dau-GnRH-III derivative conjugates were well tolerated and had significant antitumour effect on colon carcinoma-bearing mice.

New derivatives of GnRH as potential anticancer therapeutic agents.

GnRH (gonadotropin-releasing hormone), a decapeptide produced by the hypothalamus, plays an important role in the reproduction by regulating the pituitary-gonadal axis. Continuous high doses of GnRH or its superactive agonists result in desensitization of the pituitary gonadotropes and a suppression of sex steroid production by the gonads (chemical castration). Based on these effects, the treatment with GnRH agonists has become a widely used hormonal therapy of the sex-steroid dependent tumors. It was also demonstrated that most tumor cells contain GnRH receptors, and the direct antiproliferative effect of GnRH analogs on cancer cells might be mediated by these receptors. Development of new GnRH derivatives is focused on the decrease of their hormonal potency resulting in higher selectivity of the antitumor activity. One of the most promising natural GnRH analogs, lamprey (l) lGnRH-III, was isolated from see lamprey. This variant of GnRH binds to GnRH receptors and inhibits proliferation of various cancer cells. However, its endocrine effect is insignificant in mammals. lGnRH-III dimers and conjugates were prepared and were shown to have increased antiproliferative effects on various cancer cells, while their hormonal activity was lower than that of the native hormone. lGnRH-III was applied as targeting moiety to deliver anticancer agents to tumor cells. Research data concerning lGnRH-III and its analogs represent a new outlook for research trends of the application of GnRH compounds in cancer chemotherapy. Studies on the effects of lGnRH-III derivatives including antiproliferative effects, cytotoxicity, hormonal actions, and enzymatic stability are reviewed in this article.

Increase of hypophyseal hormone levels in male head and neck cancer patients.

Head and neck squamous cell carcinoma (HNSCC) develops in at least 80% of cases in men with a history of smoking and heavy alcohol consumption, still it is only diagnosed in a small proportion of alcoholics. Endocrine milieu is an important factor in carcinogenesis and prognosis of several cancer types. The aim of our study was to investigate sex steroid and hypophyseal hormone status of male HNSCC patients in comparison to healthy volunteers and to patients with alcoholic liver disease, to determine possible hormonal alterations characteristic of cancer. Liver function (GGT level), and serum levels of gonadotropic hormones (FSH, LH, prolactin), sex steroids (estradiol, progesterone, testosterone) and sex hormone-binding globulin (SHBG) were compared in 130 male HNSCC patients, 54 patients with alcoholic liver disease but no known cancer, and 56 healthy controls. We found abnormal values of liver function in both HNSCC patients and alcoholics compared to healthy controls, suggesting the presence of alcoholic liver disease in the former group as well. On the other hand, a significant elevation in the level of DHEA, FSH and LH was observed in cancer patients exclusively. As a conclusion, abnormal alterations in sex steroid hormone levels can frequently be found in HNSCC patients, which may be caused in part by the alcoholic liver damage accompanying the disease. The significant increase in FSH and LH serum levels, observed only in the cancer patients, indicates that these hormones may play a role in the development and/or progression of HNSCC.

Structure-activity study on the LH- and FSH-releasing and anticancer effects of gonadotropin-releasing hormone (GnRH)-III analogs.

UNLABELLED: GnRH-III was reported to have selective FSH-releasing activity in rats and significant anticancer potency on human breast cancer cells. To improve either of these effects, 14 analogs were synthesized and investigated for FSH/LH stimulation and breast cancer inhibition. Analogs with single amino acid changes in positions 5-7 or 10 showed small or no difference in the FSH- or LH-releasing activity compared with GnRH-III but their anticancer potency decreased significantly. Modification of the terminal amino acids, side chain cyclization at the 6-8 regions, or combined amino acid changes at positions 4, 6 and/or 8 resulted in the decrease of both effects. Gonadotropin-releasing activity of Arg(8)-GnRH-III was improved 3-11-fold. A copolymer conjugate of GnRH-III showed 2-3-fold anticancer activity while losing endocrine potency. CONCLUSION: The activation of GnRH-receptors on pituitary and breast cancer cells requires a specific structure and/or conformation that makes possible to improve the anticancer selectivity of GnRH analogs.

Structure, enzymatic stability and antitumor activity of sea lamprey GnRH-III and its dimer derivatives.

Direct antitumor activity of sea lamprey (Petromyzon marinus) gonadotropin-releasing hormone III (Glp-His-Trp-Ser-His-Asp-Trp-Lys-Pro-Gly-NH(2); lGnRH-III) was described on several tumor cells. To improve the selectivity of antitumor effects without increasing the hormone releasing activity and to enhance the enzymatic stability, lGnRH-III dimers were prepared via disulfide bond formation. Our results demonstrate that the lGnRH-III dimer derivatives exhibited higher antiproliferative effect and enzymatic stability in comparison with the native lGnRH-III, while lower LH-releasing potency was determined. In order to find a correlation between the biological and structural features of these compounds, the conformation of lGnRH-III and its dimer derivatives was determined by ECD, VCD, FT-IR and (1)H NMR.

[Clinical significance of serum thyroglobulin and antithyroglobulin antibody in differentiated thyroid cancer after thyroid ablation]. / Szérum thyreoglobulin és thyreoglobulinellenes antitest meghatározásának klinikai jelentôsége pajzsmirigyrákkal mûtött betegek vizsgálata során.

Serum thyroglobulin (Tg) is a suitable marker for differentiated thyroid carcinoma following total thyroid ablation. Between 1998 and 2003, serum samples from 715 papillary and 179 follicular tumor patients treated with total/nearly total thyroidectomy and radioiodine ablation therapy were collected. According to the "Guidelines for Oncotherapy in Hungary", serum Tg, antithyroglobulin antibody (TgAb), TSH and FT4 levels were measured in periods of 3 months following the first treatment and of 6 months after 2 years. In the present work the prognostic value of Tg and TgAb data of cancer patients with hormone substitution therapy were evaluated individually and retrospectively. Serum Tg and TgAb concentrations were measured with a highly sensitive immunoradiometric (IRMA) method, and with a second generation, broad epitope specificity competitive radioimmunoassay, respectively. TSH levels determined by fourth generation LIAISON kit were in a range of 0.05-0.10 mIU/L. Accuracy of measuring of Tg <1 ng/ml made it possible to select the low cut-off level (Tg <2 ng/ml) following total thyroidectomy. In the predominant part of TSH-suppressed patients (746/774, 96%) the serum Tg concentration was below the cut-off level of 2 ng/ml. The sensitivity of Tg determination in 59 TSH-suppressed thyroid cancer patients with lung and bone metastases was as high as 86 to 100%. On the contrary, the number of false negative data was high in cases with lymph node metastases of papillary cancer, and sensitivity did not exceed 62%. Specificity and sensitivity of Tg in TgAb negative patients were 91 to 100%. Based on our results it could be concluded that measuring of Tg and TgAb, using a current IRMA method and a second generation RIA kit, proved to be effective tools for the postoperative monitoring of differentiated thyroid tumours. It has to be noted that determination of TgAb is highly recommended for the adequate interpretation of serum Tg levels. Persistently high and/or increasing serum TgAb concentration with low Tg result had a diagnostic value during the follow-up and can be connected with the recurrence or persistence of the differentiated thyroid cancer.