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Michael Friedrich

Publications and source records attributed to Michael Friedrich.

16 recordsLinked to original sources
PubMed2006

Santorini eruption radiocarbon dated to 1627-1600 B.C.

Precise and direct dating of the Minoan eruption of Santorini (Thera) in Greece, a global Bronze Age time marker, has been made possible by the unique find of an olive tree, buried alive in life position by the tephra (pumice and ashes) on Santorini. We applied so-called radiocarbon wiggle-matching to a carbon-14 sequence of tree-ring segments to constrain the eruption date to the range 1627-1600 B.C. with 95.4% probability. Our result is in the range of previous, less precise, and less direct results of several scientific dating methods, but it is a century earlier than the date derived from traditional Egyptian chronologies.

Archaeology↗
PubMed2005

Vascular targeting in pancreatic cancer: the novel tubulin-binding agent ZD6126 reveals antitumor activity in primary and metastatic tumor models.

ZD6126 is a novel vascular-targeting agent that acts by disrupting the tubulin cytoskeleton of an immature tumor endothelium, leading to an occlusion of tumor blood vessels and a subsequent tumor necrosis. We wanted to evaluate ZD6126 in primary and metastatic tumor models of human pancreatic cancer. Nude mice were injected orthotopically with L3.6pl pancreatic cancer cells. In single and multiple dosing experiments, mice received ZD6126, gemcitabine, a combination of both agents, or no treatment. For the induction of metastatic diseases, additional groups of mice were injected with L3.6pl cells into the spleen. Twenty-four hours after a single-dose treatment, ZD6126 therapy led to an extensive central tumor necrosis, which was not seen after gemcitabine treatment. Multiple dosing of ZD6126 resulted in a significant growth inhibition of primary tumors and a marked reduction of spontaneous liver and lymph node metastases. Experimental metastatic diseases could be significantly controlled by a combination of ZD6126 and gemcitabine, as shown by a reduction of the number and size of established liver metastases. As shown by additional in vitro and in vivo experiments, possible mechanisms involve antivascular activities and subsequent antiproliferative and proapoptotic effects of ZD6126 on tumor cells, whereas direct activities against tumor cells seem unlikely. These data highlight the antitumor and antimetastatic effects of ZD6126 in human pancreatic cancer and reveal benefits of adding ZD6126 to standard gemcitabine therapy.

Animals↗
PubMed2004

Analysis of the vitamin D system in basal cell carcinomas (BCCs).

Using real-time PCR (LightCycler) and immunohistochemistry, we have analyzed expression of key components of the vitamin D system in basal cell carcinomas (BCCs) and normal human skin (NS). Increased VDR-immunoreactivity was demonstrated in BCCs using a streptavidin-peroxidase technique. RNA expression of vitamin D receptor (VDR) and of main enzymes involved in synthesis and metabolism of calcitriol (vitamin D-25-hydroxylase [25-OHase], 25-hydroxyvitamin D-1alpha-hydroxylase [1alpha-OHase], 1,25-dihydroxyvitamin D-24-hydroxylase [24-OHase]) was detected in BCCs and NS. Expression levels were determined as ratios between target genes (VDR, 1alpha-OHase, 25-OHase, 24-OHase) and the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as internal control. Median of mRNA ratios for VDR/GAPDH (BCCs: 16.54; NS: 0.00021), 1alpha-OHase/GAPDH (BCCs: 0.739; NS 0.000803) and 24-OHase/GAPDH (BCCs: 0.00585; NS 0.000000366) was significantly (Wilcoxon-Mann-Whitney U-test) elevated in BCCs. In contrast, median of mRNA ratio for 25-OHase/GAPDH (BCCs: 0.17; NS: 0.016) was not significantly altered in BCCs as compared to NS. Additionally, we report for the first time expression of 1alpha-OHase splice variants in BCCs and NS, that were detected using conventional RT-PCR. In conclusion, our findings provide supportive evidence for the concept that endogeneous synthesis and metabolism of vitamin D metabolites as well as VDR expression may regulate growth characteristics of BCCs. New vitamin D analogs that exert little calcemic side effects, their precursors, or inhibitors of 24-OHase may offer a new approach for the prevention or therapy of BCCs. The function of alternative transcripts of 1alpha-OHase that we describe here for the first time in BCCs and NS and their effect on activity level has to be investigated in future experiments.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2003

Granulomatous mastitis.

INTRODUCTION: Granulomatous mastitis (GM) is a rare disease which predominantly occurs in premenopausal women shortly after their last childbirth. ETIOLOGY: Its etiology is unclear, however, the disease has been shown to be correlated with breast-feeding and the use of oral contraceptives. An autoimmune component has also been discussed. PRESENTATION: It presents with the clinical symptoms of galactorrhea, inflammation, breast mass, tumorous indurations and ulcerations of the skin. In mammography and sonography nodular opacities and hypoechoic nodules are found. Very often clinical and radiological findings mimic breast cancer. HISTOLOGICAL DIAGNOSIS: The diagnosis is made by histopathology. Histological features in GM include signs of a chronic granulomatous inflammation with giant cells, leucocytes, epitheloid cells and macrophages as well as abscesses. TREATMENT: Therapy of GM consists of complete surgical excision combined with oral steroid therapy, eventually in combination with anti-inflammatory drugs or colchicine. Use of methotrexate has also been successful. In case of formation of abscesses antibiotic therapy should be applied before steroid therapy. Immune-suppressive therapy should be performed until complete remission as rates of recurrence can be up to 50%.

Adrenal Cortex Hormones↗
PubMed2003

Identification of an HLA-A*02 restricted immunogenic peptide derived from the cancer testis antigen HOM-MEL-40/SSX2.

HOM-MEL-40/SSX2 is a SEREX-defined cancer testis antigen with frequent expression in various human neoplasms. To search for HLA-A*0201 restricted peptides that induce HOM-MEL-40/SSX2-specific CD8+ responses in breast cancer patients, we used the SYFPEITHI algorithm to identify three HOM-MEL-40/SSX2-derived nonamers with high binding affinity for HLA-A*0201, which has a prevalence of 40% in the Caucasian population. Of the three peptides, p41-49 and p103-111 but not p167-175 had been shown to be processed by the proteasome. Only stimulation with p103-111 induced HOM-MEL-40-specific CTLs in 5/7 patients with HOM-MEL-40/SSX2 positive breast cancers and in 6/11 healthy controls. HLA-A*0201 restriction of p103-111 was demonstrated by blocking with specific antibodies. The natural processing and presentation of p103-111 was demonstrated by the recognition of the HOM-MEL-40/SSX2 positive cell line SK-MEL-37 and of COS7/A2 cells transfected with HOM-MEL-40/SSX2 by p103-111 specific CD8+ cells. No correlation was found between CD8+ T-cell responses against p103-111 and anti-HOM-MEL-40/SSX2 antibody titers in the serum of patients, suggesting that CD8+ and B-cell responses against HOM-MEL-40/SSX2 are regulated independently. p103-111 holds promise as a broadly applicable peptide vaccine for patients with HOM-MEL-40/SSX2 positive neoplasms.

Aged↗
PubMed2003

Analysis of the vitamin D system in cervical carcinomas, breast cancer and ovarian cancer.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) is the biologically active metabolite of vitamin D and has been shown to regulate the growth of various cell types. There are two principal enzymes involved in the formation of circulating 1,25(OH)2D3 from vitamin D, the vitamin D 25-hydroxylase (25-OHase) and the 1alpha-hydroxylase (1alpha-OHase). Recently, extrarenal activity of 1alpha-OHase has been reported in various cell types. The aim of this study was to analyze expression of VDR and the main enzymes involved in the synthesis and metabolism of calcitriol in gynecological malignancies and corresponding normal tissue. Expression of VDR, 25-OHase, 1alpha-OHase, and 24-OHase was analyzed in breast carcinomas (BC), ovarian cancer (OC), cervix carcinomas (CC) and normal corresponding tissues using real-time PCR and specific hybridization probes as well as using immunohistochemistry. RNA for VDR, 1alpha-OHase, 24-OHase and 25-OHase was up-regulated in breast cervical and ovarian carcinomas as compared to normal tissue. VDR immunoreactivity was increased in breast and ovarian cancer and in cervix carcinomas as compared to normal corresponding tissue. Our findings indicate that cervical carcinomas, breast cancer and ovarian cancer may be considered as potential targets for prevention or therapy with new vitamin D analogs that exert little or no calcemic side effects or by pharmacological modulation of 1,25(OH)2D3 synthesis and metabolism in these tumor cells.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMedDate not supplied

Analysis of vitamin D-receptor (VDR) and retinoid X-receptor alpha in breast cancer.

The expression of vitamin D-receptor (VDR) and retinoid X-receptor alpha (RXR-alpha) has been analysed immunohistochemically in benign (n = 62 and n = 5 respectively) and malignant (n = 228 and n = 15 respectively) breast tissue samples using a monoclonal antibody 9A7gamma against VDR and a polyclonal antibody against RXR-alpha. A recently developed immunoreactive scoring method (IRS) was employed. The expression of VDR was detected at the RNA-level using the reverse transcriptase-polymerase chain reaction. A statistically significant higher expression of VDR at the protein level was seen in breast cancer compared with benign breast tissue, whereas at the mRNA level no visible differences in the expression of VDR were found. A higher expression of RXR-alpha was seen in breast cancer compared with benign breast tissue. Our findings indicate that breast tissue may be a new target organ for therapeutically applied vitamin D and retinoid analogues. VDR and RXR-alpha are upregulated at the protein level in breast carcinomas as compared to normal breast tissue, indicating a possibly increased sensitivity to therapeutically applied vitamin D analogues. New vitamin D analogues exerting less calcemic side effects may be promising new drugs for the treatment or chemoprevention of breast carcinomas as well as of precancerous breast lesions. Combination therapies of vitamin D and retinoid analogues with fewer side effects seen promising for the treatment of breast cancer.

Antibodies↗
PubMedDate not supplied

Analysis of 25-hydroxyvitamin D3-1alpha-hydroxylase in cervical tissue.

UNLABELLED: 1,25(OH)2D3 suppresses proliferation and induces differentiation in various cell types, including epithelial cells. Recently, extrarenal activity of 1alpha-hydroxylase for 25(OH)D3 has been reported in various cell types including macrophages, keratinocytes and prostate and colon cancer cells. The aim of this study was to analyze the expression of 1alpha-hydroxylase for 25-hydroxyvitamin D3 in normal cervical samples and in cervical cancer, in order to investigate whether cervical tissue possesses the capacity to produce 1,25(OH)2D3 from 25(OH)D3, indicating that 1,25(OH)2D3 may be a locally produced hormone that controls proliferation in cervical tissue and that alterations in local production of 1,25(OH)2D3 may be involved in tumourigenesis of cervical cancer. MATERIALS AND METHODS: RNA was extracted from normal cervical tissue (n=4), cervical carcinomas (n=8) and HeLa cells using the method of Chomczynski. RNA was reverse-transcribed and RNA-levels were semiquantitatively detected by PCR. RESULTS: mRNA of 1alpha-hydroxylase for 25-hydroxyvitamin D3 was detected in more than 50% of samples analyzed in normal cervical tissue and in cervical cancer with no visible difference between either group. mRNA of 1alpha-hydroxylase for 25-hydroxyvitamin D3 was detected in HeLa cells as well. CONCLUSION: 25(OH)D3-1alpha-hydroxylase is expressed in normal cervical tissue, in cervical cancer and in HeLa cells. Thus, normal cervical and cervical cancer cells seem to be able to synthesize 1alpha, 25(OH)2D3 that may be of significant importance for the growth control in normal and malignant cervical tissue. Normal cervical tissue and cervical cancer cells may be new targets for cancer prevention or cancer treatment with precursors of biologically active vitamin D analogues.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMedDate not supplied

Vitamin D receptor (VDR) expression is not a prognostic factor in cervical cancer.

BACKGROUND: The aim of this study was to analyze whether VDR status is a prognostic factor that may be of importance for the assessment of recurrence in cervical cancer. MATERIALS AND METHODS: VDR-, Ki-67- and p53-status were analyzed immunohistochemically in cervical cancer patients (n=50) and in benign cervical tissue (n=15). The histopathological data of the tumours were evaluated. RNA was extracted from normal cervical tissue (n=4) and cervical carcinomas (n=8) using the method of Chomczynski. RNA was reverse-transcribed and RNA-levels were semiquantitatively detected by PCR. RESULTS: The expression of VDR was significantly increased in cervical cancer compared to normal cervical tissue on the protein-level but not on the RNA-level. No statistically significant correlations were found comparing VDR status with histopathological data (tumour stage, lymph node status, grading, histological tumour type), with the expression of the proliferation marker Ki-67 and of the tumour suppressor gene p53. CONCLUSION: Our findings indicate that VDR protein expression is not a prognostic factor in cervical cancer. The strong I/DR immunoreactivity that we observed in cervical cancer specimens supports the body of evidence that cervical cancer may be a target for therapeutically applied vitamin D analogues.

Adenocarcinoma↗
PubMedDate not supplied

Vitamin D receptor (VDR) expression is not a prognostic factor in breast cancer.

Breast cancer is characterized by its early haematogenous dissemination. Current modalities of risk assessment in lymph node-negative patients, to determine which patients should receive adjuvant chemotherapy, are not effective. The aim of this study was to analyze whether vitamin D receptor (VDR) status is a prognostic factor that may be of importance for the assessment of recurrence in breast cancer. VDR expression was analyzed immunohistochemically in breast cancer patients (n=228). No statistically significant correlations were found comparing VDR expression with histopathological data (tumor stage, lymph node status, grading, histological tumor type), with the expression of estrogen receptors (ER) or progesterone receptors (PR), with the proliferation marker Ki-67, with the tumor suppressor gene p53 or with the S-phase index. Our findings indicate that VDR protein expression is not a prognostic factor in breast cancer. The strong VDR immunoreactivity that we observed in breast cancer specimens supports the body of evidence that breast cancer may be a target for therapeutically applied vitamin D analogues.

Breast Neoplasms↗
PubMedDate not supplied

Immunohistochemical analysis of 1,25-dihydroxyvitamin-D3-receptors, estrogen and progesterone receptors and Ki-67 in ovarian carcinoma.

BACKGROUND: The aim of this study was to analyze immunohistochemically the expression of VDR in normal and carcinomatous ovarian tissue to evaluate whether ovarian tissue may be a new potential target for biologically active vitamin D analogues. MATERIALS AND METHODS: The expression of 1,25-dihydroxyvitamin-D3-receptors (VDR) was immunohistochemically investigated in ovarian carcinomas (n=40). VDR immunoreactivity (mAb 9A7gamma) was compared with the staining pattern of the proliferation marker Ki-67, of the estrogen receptors (ER) and of the progesterone receptors (PR). The percentage of positive tumour cells (PP), the intensity of staining (SI) and a resulting immunoreactivity score (IRS) were determined for the semiquantitative evaluation of VDR-, ER- and PR-expression. RESULTS: A total of 16.7% of the normal surface ovarian epithelium was VDR-negative, while the remaining 83.3% revealed weak to moderate VDR immunoreactivity. Moderate to strong nuclear immunoreactivity for VDR was detected in almost all ovarian carcinomas analyzed. Both the intensity of VDR immunostaining and the number of VDR-positive cells were significantly increased in ovarian carcinomas as compared to normal ovarian tissue. Analyzing coexpression of VDR with the proliferation marker Ki-67 or with the estrogen and progesterone receptors, no significant correlation was found. CONCLUSION: Our findings indicate that: (I) VDR expression is increased in ovarian carcinomas as compared to normal ovarian tissue. (II) Up-regulation of VDR in ovarian carcinomas is not exclusively induced by an increase of proliferation, but by different unknown mechanisms. (III) Expression of VDR in ovarian carcinomas is independently regulated from the expression of ER and PR. (IV) Ovarian tissue may be a new target organ for therapeutically applied vitamin D analogues exerting fewer calcemic side-effects. New vitamin D analogues may be promising drugs for the treatment of advanced ovarian carcinomas.

Cell Division↗
PubMedDate not supplied

Vitamin D analogs in cancer prevention and therapy.

The Second International Symposium on "Vitamin D Analogs in Cancer Prevention and Therapy", was held in Lübeck, Germany, May 7-8, 2005. This meeting was specifically designed to summarize the latest developments in the epidemiology, molecular biology, metabolism, biological effects and clinical use of vitamin D analogs, leading to new concepts for their application in cancer prevention and therapy. Forty keynote lectures were presented at the Symposium and the following conclusions were summarized at a round-table discussion. Cancer Prevention: Evidence from epidemiological and laboratory investigations now convincingly demonstrate that vitamin D deficiency and insufficiency are underrecognized worldwide problems that are associated with several health problems, including the higher prevalence and unfavorable course of cancer. There is an urgent need for additional well-designed studies to define the optimal vitamin D status (25-hydroxyvitamin D serum level) and for campaigns to better inform the public and medical profession alike about the health risks related to vitamin D deficiency and insufficiency. Cancer Therapy: Knowledge of the underlying molecular mechanisms that mediate the antitumor effects of vitamin D analogs has expanded greatly during recent years and results from the first clinical trials indicate that such analogs hold promise for cancer therapy, most probably in combination with other agents. However, the era of vitamin D analogs in cancer therapy has just begun and efforts to perform well-designed clinical studies and to develop new analogs with fewer systemic side-effects have to continue.

Humans↗
PubMedDate not supplied

Analysis of 25-hydroxyvitamin D3-1alpha-hydroxylase in normal and malignant breast tissue.

BACKGROUND: The presence of extra-renal 25-hydroxyvitamin D3 [25(OH)D3]-1alpha-hydroxylase (1alpha-OHase) has been reported in several cell types including prostate and colon cancer cells. Additionally, alterations in the local production of 1alpha,25-dihydroxyvitamin D [1alpha,25(OH)2D3] have been implicated in the tumorigenesis of these malignancies. The aim of this study was to analyze whether normal breast tissue or breast cancer cells expressed 1alpha-OHase and to evaluate whether breast tissue possessed the capacity to produce 1alpha,25(OH)2D3 from 25(OH)D3. MATERIALS AND METHODS: Total RNA was extracted from normal breast tissue (n = 11), breast carcinomas (n = 12) and cultured MCF-7 breast cancer cells for real-time (LightCycler using specific hybridization probes) and conventional PCR analysis. RESULTS: mRNA for 1alpha-OHase was detected in breast cancer tissue and in MCF-7 breast cancer cells. Interestingly, the mRNA levels for 1alpha-OHase were significantly increased in breast cancer compared to normal breast tissue. When the MCF-7 cells were treated with 1alpha,25(OH)2D3, cell proliferation was inhibited in a dose-dependent manner. Incubation of the MCF-7 cells with [3H]-25(OH)D3 resulted in its conversion to [3H]-1,25(OH)2D3. The 1alpha-OHase activity in the MCF-7 cells was blocked by a specific cytochrome P450 inhibitor, clotrimazole. CONCLUSION: The data suggest that at least breast cancer cells expressed 1alpha-OHase mRNA and, therefore, might have the ability to synthesize 1alpha,25(OH)2D3 within the cells. The local production of 1alpha,25(OH)2D3 might play an important role in regulating the proliferation and differentiation of breast cells. We hypothesize that alterations in the local production of 1alpha,25(OH)2D3 may be involved in the tumorigenesis of breast cancer. Additionally, breast cancer may be a target for treatment with precursors of biologically-active vitamin D analogs.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMedDate not supplied

Cutaneous photosynthesis of vitamin D: an evolutionary highly-conserved endocrine system that protects against environmental hazards including UV-radiation and microbial infections.

Phytoplankton and zooplankton have been producing vitamin D for more than 500 million years. While the function of vitamin D in the physiology of lower non-vertebrate organisms is not well understood, it is known that most vertebrates need vitamin D to develop and maintain a healthy mineralized skeleton. However, recent findings have demonstrated that 1,25(OH)2D, the biologically-active vitamin D metabolite, exerts a multitude of important physiological effects independently of the regulation of calcium and bone metabolism. These new functions of vitamin D include protection against cancer and other diseases in various tissues. In this review, current knowledge of an additional new function of the cutaneous photosynthesis of vitamin D, that has recently emerged, is summarized: the role of vitamin D as an evolutionary highly-conserved endocrine system that protects the skin and other tissues against environmental hazards, including ionizing and UV-radiation, microbial infections and oxidative stress, is discussed.

Endocrine System↗
PubMedDate not supplied

Vitamin D--metabolism in the human breast cancer cell line MCF-7.

BACKGROUND: The three main vitamin D metabolizing enzymes, vitamin D3-25-hydroxylase (25-OHase, 25-hydroxylase), 25-hydroxyvitamin D3-1alpha-hydroxylase (1alpha-OHase, 1alpha-hydroxylase) and 25-hydroxyvitamin D3-24-hydroxylase (24-OHase, 24-hydroxylase), have been described in malignant breast tissue. This in vitro study aimed to obtain more information regarding the regulation of these enzymes in the human breast cancer cell line MCF-7. MATERIALS AND METHODS: Vitamin D receptor (VDR)- positive MCF-7 cells in culture were stimulated with the vitamin D metabolites vitamin D3, 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 for 24, 48; 72 and 96 hours in physiological and supraphysiological concentrations. The expressions of 25-hydroxylase, 1alpha-hydroxylase and 24-hydroxylase and their changes after stimulation were assessed by real-time PCR. RESULTS: The expression of 25-hydroxylase was slightly influenced by vitamin D3. The expression of 1alpha-hydroxylase was induced after stimulation with vitamin D3 and 25-hydroxyvitamin D3. Stimulation with 1,25-dihydroxyvitamin D3 markedly increased the expression of 24-hydroxylase time- and dose-dependently. CONCLUSION: Our results demonstrated that MCF-7 cells are able to regulate the expression of 24-hydroxylase. This might be a mechanism for these tumor cells to protect themselves against the antiproliferative and apoptosis-inducing effects of calcitriol.

Breast Neoplasms↗