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A Hobisch

Publications and source records attributed to A Hobisch.

At least 73 records · Page 4Linked to original sources
PubMed1995

Dendritic antigen-presenting cells from the peripheral blood of renal-cell-carcinoma patients.

Dendritic cells are considered to be the initiators of immune responses, including those directed against tumors. Clinical research on dendritic cells was long hampered by the limited availability of these cells. The recent identification of cytokine combinations that mobilize dendritic cells with potent antigen-presenting cell function from peripheral blood represented a major progress. We show in this study that substantial numbers of dendritic cells can be obtained from the peripheral blood of patients with renal-cell carcinoma. The procedure requires a relatively small blood sample (40 ml) and avoids both priming of the patient with granulocyte-colony stimulating factor and leukapheresis. Approximately 2 to 8 million cells with the characteristics of dendritic cells could be obtained: phase-contrast microscopy revealed the typical cytoplasmic processes or veils; phenotypic analysis confirmed expression of dendritic-cell-associated molecules, including MHC class II, CD1a, CD4, ICAM-1 (CD54), LFA-3 (CD58), B7-1 (CD80) and B7-2 (CD86), and absence of T-cell, B-cell and monocyte markers; in addition, these cells rapidly attached to and migrated on collagen-type-1-coated surfaces. Interestingly, attachment was accompanied by acquisition of the CD14 antigen; functionally, cultured dendritic cells proved to be very potent co-stimulators of the phytohemagglutinin-induced proliferation of autologous tumor-infiltrating lymphocytes. The reproducible growth of functional dendritic cells from cancer patients is encouraging for the design of immunotherapy protocols.

Adult↗
PubMed1995

Mutant androgen receptors in prostatic tumors distinguish between amino-acid-sequence requirements for transactivation and ligand binding.

Mutant androgen receptors are thought to contribute to hormone resistance in prostate carcinoma. The part they play in this process, however, is ill-defined. Here we report on transactivation by 2 mutant androgen receptors from prostatic tumors with single amino-acid exchanges in their hormone-binding domains. These exchanges enhance the transactivation property of the receptors, particularly to androsterone and androstanediol, 2 metabolized derivatives of testosterone present in the prostate. Additionally, they enhance the transactivation potential of the mutant receptors to hydroxyflutamide, an anti-androgen frequently used in hormone ablation therapy. The increased transactivation by the mutant receptors did not result from altered affinity of the receptors to the inducing ligands nor from measurable changes in conformation of the liganded receptors. Thus the single amino-acid exchanges identify differences in amino-acid-sequence requirements for transactivation and ligand binding in the hormone-binding domain of the androgen receptor. These results provide new insights into ligand-dependent transactivation, and form a framework for the search for effective antagonists to be used in prostate-cancer therapy.

Amino Acid Sequence↗
PubMed1995

Tumor-infiltrating T lymphocytes from renal-cell carcinoma express B7-1 (CD80): T-cell expansion by T-T cell co-stimulation.

B7-1 (CD80) provides co-stimulation for T-cell activation by interacting with CD28 or CTLA4. Here we demonstrate the expression of B7-1 in freshly isolated and cultured lymphocytes from renal-cell carcinoma. In fresh preparations of lymphocytes infiltrating renal-cell-carcinoma tissue, B7-1 mRNA could readily be detected by reverse transcription PCR, and 2-color flow-cytometry analysis revealed substantial B7-1 expression on T cells from these isolates. As expected, tumor-derived T cells also expressed CD28, the B7 receptor. While B7-1 expression of tumor-derived T cells was maintained during culture in interleukin-2-supplemented medium, CD28 expression was further enhanced. We also show that B7-1 is functionally involved in T-cell expansion: anti-B7-1 MAb inhibited the PHA-induced proliferation of tumor-derived B7-1+ T cells (35%) in the absence of exogenous antigen-presenting cells, indicating that B7-1 mediates T-T cell co-stimulation (self-co-stimulation). Our data demonstrate that T cells infiltrating renal-cell carcinoma express B7-1, and that mutual co-stimulation via the B7-1/CD28 pathway contributes to the interleukin-2-driven expansion of tumor-derived T cells in vitro. The frequency of B7-1+ T cells in tumor lesions and the level of B7-1 on these cells may determine the time course of T-cell expansion in vivo. Self-co-stimulation, however, might also represent one mechanism leading to the state of suppression or anergy characteristic of tumor-infiltrating lymphocytes.

B7-1 Antigen↗
PubMed1995

Distant metastases from prostatic carcinoma express androgen receptor protein.

Nearly all primary prostatic carcinomas have been found to express the androgen receptor (AR) protein, which is the intracellular mediator of androgen action. To gain a better insight into the mechanisms of androgen independence of advanced prostatic carcinoma, it is important to know whether the AR is also present in metastases of androgen-independent tumors. We have assessed the status of the AR and the prostate-specific antigen in 22 metastases of 18 patients with progressive prostate cancer. In 18 cases, the metastases were localized in bone, in 3 cases in the epidural space, and in 1 case in the periosteum. All but one patient had received some kind of endocrine treatment for prostatic carcinoma. Paraffin-embedded tissue sections were stained for the AR following a streptavidinbiotin-peroxidase protocol with the polyclonal antibody PG-21, which is directed against amino acids 1 through 21 of the rat and the human AR. The percentage of AR-positive cells was evaluated on the basis of an arbitrary 4-point scale. All 22 tumor metastases displayed AR positivity. One AR-positive metastatic lesion did not stain for prostate-specific antigen, but in all other metastases, this protein was detected by means of immunohistochemistry. The present study provides evidence that, unlike androgen-independent prostatic carcinoma cell lines, distant prostatic carcinoma metastases do express the AR. These findings indicate that the AR may be involved in the progression of prostate cancer.

Bone Neoplasms↗
PubMed1995

Activation of the androgen receptor by polypeptide growth factors and cellular regulators.

The polypeptide growth factors insulin-like growth factor I (IGF-I), epidermal growth factor (EGF), and transforming growth factor-alpha (TGF-alpha); second-messenger cyclic adenosine monophosphate (cAMP): protein kinase activators; and neurotransmitters were found to activate the estrogen (ER), progesterone (PR), and glucocorticoid receptor (GR) either in the absence of their natural ligands or synergistically with the respective hormone. There is now evidence of coupling of signaling pathways involving the androgen receptor (AR). Three polypeptide growth factor, IGF-I, keratinocyte growth factor (KGF), and EGF, stimulated AR-mediated reporter-gene transcription in the absence of androgen in DU-145 cells, which were cotransfected with the reporter gene and an AR expression vector. IGF-I effects were observed irrespective of the promoter driving the reporter gene. This growth factor increased the prostate-specific antigen (PSA) level in LNCaP cells, which contain endogenous AR. In CV-1 cells, which transiently express the AR, second-messenger cAMP potentiated effects of testosterone in stimulation of AR-mediated reporter-gene activity. Inhibition of androgen-stimulated chloramphenicol acetyltransferase (CAT) activity in the LNCaP cell line was achieved with retinoic acid. Stimulation and inhibition of prostatic carcinoma cell growth by polypeptide growth factors and cellular regulators may depend on the presence of the AR in an androgen-depleted environment.

Animals↗
PubMed1995

Androgen receptor alterations in patients with disturbances in male sexual development and in prostatic carcinoma.

The androgen receptor, a ligand-activated nuclear transcription factor belonging to the large superfamily of nuclear receptors, mediates the intracellular action of androgens. It plays a central role in male sexual development and in prostatic carcinoma as a target of endocrine therapy. We have looked for androgen receptor mutations as a cause of male sexual ambiguity and as a possible reason for failure of androgen ablation therapy on prostatic carcinoma. In 5 patients of 2 families with perineoscrotal hypospadia and undescended testes, we have identified a mutation ala596-->thr in the DNA-binding domain of the androgen receptor. This mutation interferes with DNA binding of the receptor. Reactivation of this mutant receptor by binding of an antibody or by interaction with other proteins and by exchange of the amino acid thr602-->ala indicates that the dimerization step is affected. A point mutation ser703-->gly was detected in a newborn male child with perineoscrotal hypospadias. This mutation decreased receptor-hormone affinity. As a consequence its transactivation activity was dependent on the androgen concentration. Although the molecular mechanisms of these two mutations are completely different, both resulted in partial androgen insensitivity and interfered with virilization in the affected patients. A different kind of mutation was present in a tumor specimen derived from an advanced therapy-resistant prostatic carcinoma. This point mutation resulted in exchange of valine-->methionine at amino acid position 715 in the receptor protein. In contrast to the former two mutations this receptor showed a gain in function.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Diagnostic laparoscopic retroperitoneal lymph node dissection for non seminomatous testicular tumor.

Retroperitoneal lymph node dissection for nonseminomatous testicular tumor. A modified retroperitoneal lymph node dissection for stage I testicular tumor has been described by Weissbach. We have developed a two-step procedure for performing laparoscopic retroperitoneal lymph-adenectomy within these boundaries. In the first step, a ventral approach is used. The colon is dissected free, then the spermatic vein is excised, and the borders of the dissection are defined. Removal of retroaortic and retrocaval nodal tissue is technically not feasible via the ventral approach. Therefore, in the second step, a lateral approach is employed, which is the key to success since it permits easy transection of the lumbar vessels. Thus complete lymph node dissection can be achieved. Between August 1992 and March 1994 this procedure was performed in 15 patients. In nine patients, the tumor was on the right side and in six on the left. Conversion to open surgery was necessary in two patients because of uncontrollable bleeding and a large metastasis, respectively. Microscopic metastases were detected in two other patients. Apart from the above-mentioned bleeding no major complications occurred; no blood transfusion were required. The results obtained so far demonstrate that this procedure is technically feasible. Therefore, we have decided to perform laparoscopic retroperitoneal lymphadenectomy also in patients with stage II B tumors who have received chemotherapy; to date one patient with a left-sided stage II B tumor has been operated on successfully.

Adult↗
PubMed1995

Testicular seminomas are aneuploid tumors.

BACKGROUND: Distinct ploidy patterns of germ cell tumors and aneuploidy of classic seminoma are of central importance in a current concept designating seminoma as a stage in tumor evolution preceding all nonseminomatous germ cell tumors. Whereas cytogenetic studies almost constantly revealed numerical chromosomal aberrations in seminomas in line with this pathogenetic model, ploidy determination by DNA cytometry yielded highly controversial results on the frequency of diploid seminomas. EXPERIMENTAL DESIGN: Twenty-two classic seminomas were investigated in a comparative manner by DNA flow and DNA image cytometry on nuclei isolated from fresh as well as formalin-fixed tumors. The cellular composition of the tumors, i.e., the number of neoplastic, interstitial, and lymphoid cells was quantified in each case. RESULTS: Irrespective of the tissue preparation and fixation method, all of the tumors that were analyzed were aneuploid by image cytometry. Diploid cases were only found by flow cytometry. Thus, 1/22 cases from paraffin-embedded and 4/11 cases of native tumors showed a single diploid stemline by flow cytometry, however, they exhibited aneuploidy by image cytometry. The quantity of tumor infiltrating lymphocytes was clearly correlated with false diploidy detected by flow cytometry. CONCLUSIONS: Classic testicular seminomas are aneuploid tumors. Previous reports on diploid cases detected by flow cytometry have most likely been caused by extensive lymphocytic infiltration.

Aneuploidy↗
PubMed1994

Carcinoma in situ of the testis detected by DNA flow cytometry of testicular fine-needle aspirates.

Testicular carcinoma in situ (CIS) is usually diagnosed histologically on surgical biopsies. The present study was performed to test an alternative approach--DNA flow cytometry (FCM) of testicular fine-needle aspirates (FNA)--for the detection of this lesion. FNAs from 18 cases of testicular germ cell tumors (TGCT) and tumor adjacent parenchyma were analysed by DNA FCM. DNA histograms of all cell nuclei and histograms representing selectively the hyperdiploid compartment were analysed. The presence and extention of CIS were determined by histology and immunohistochemistry. In 16 of 18 cases, CIS was histologically present, whereas aneuploid peaks were detected in only 11 cases in DNA histograms of all cell nuclei. In the analysis of the histograms of the hyperdiploid region, 4 additional cases of CIS could be identified increasing the sensitivity to 15/16 cases (93.8%). In all but one case, the DNA indices of CIS and invasive tumors were identical. The study demonstrates that DNA FCM of testicular FNAs using the described data acquisition and analysis could also be applicable for detection of CIS in a clinical situation.

Aneuploidy↗
PubMed1994

Androgen receptor activation in prostatic tumor cell lines by insulin-like growth factor-I, keratinocyte growth factor, and epidermal growth factor.

Aberrant activation of the androgen receptor (AR) may be one of the mechanisms which contribute to progression of prostatic carcinoma to an androgen-independent stage. We investigated effects of growth factors on stimulation of the AR-mediated gene transcription in human prostatic tumor cell lines. DU-145 cells, which do not contain endogenous AR, were cotransfected with an androgen-inducible chloramphenicol acetyltransferase (CAT) reporter gene and an AR expression vector. The reporter gene (CAT) was driven either by artificial promoters consisting of one or two androgen-responsive elements in front of a TATA box or by the promoter of the prostate-specific antigen (PSA) gene, a naturally occurring androgen-inducible promoter. Insulin-like growth factor-I (IGF-I), at a concentration of 50 ng/ml, stimulated AR-mediated reporter gene transcription to the same extent as the synthetic androgen methyltrienolone. This growth factor was effective irrespective of the nature of the androgen-inducible promoter. Keratinocyte growth factor (KGF) and epidermal growth factor (EGF), at concentrations of 50 ng/ml, activated CAT reporter gene transcription only in experiments in which the artificial promoter with two androgen-responsive elements was used. Insulin-like growth factor-II and basic fibroblast growth factor displayed no effect on AR-mediated gene transcription. None of the growth factors stimulated reporter gene activity in control experiments when added to cells cotransfected with the CAT gene and an empty expression vector. AR activation by IGF-I, KGF, and EGF was completely inhibited by the pure AR antagonist casodex, showing that these effects are AR mediated. Activation of endogenous AR by growth factors was studied in the LNCaP cell line by determination of PSA secretion. IGF-I, at a concentration of 50 ng/ml, increased the PSA level in the supernatant of this cell line 5-fold. Again, the IGF-I effect on PSA secretion was blocked by casodex. Our results provide evidence that IGF-I, KGF, and EGF directly activate the AR in the absence of androgens, which means that the androgen-signaling chain may be activated by growth factors in an androgen-depleted environment. These findings may have implications for endocrine therapy for metastatic prostatic carcinoma.

Androgen Antagonists↗
PubMed1994

Androgen receptor alterations in prostatic carcinoma.

Intracellular action of androgens is mediated by the androgen receptor (AR), which is a key element of the androgen signal transduction cascade and a target of endocrine therapy for prostatic carcinoma. Therefore, the qualitative and quantitative alterations of AR expression in prostatic carcinomas and their possible implications for tumor progression and treatment are of great interest. Findings in prostatic tumor cell lines of rat and human origin suggest a reduction of AR protein expression accompanied by an increase in tumor malignancy. However, immunohistochemical studies and binding assays demonstrated presence of ARs in all histological types of prostatic tumors, in therapy-responsive as well as in therapy-unresponsive ones. AR content of prostatic tumor specimens did not correlate with outcome of endocrine therapy of advanced prostatic carcinoma in these studies. Solely the degree of heterogeneity of AR expression may be useful as an indicator of responsiveness to therapy. AR mutations have been detected in the LNCaP cell line and in three primary prostatic tumor specimens. Three of them are point mutations in the hormone-binding domain of the AR, the fourth mutation is a CAG-microsatellite depression in the N-terminus. Evidence coming from studies on AR in prostatic cancer highlights the possibility that AR structural alterations may have significance in tumor progression.

Animals↗
PubMed1994

Androgen signal transduction and prostatic carcinoma.

In the prostate, androgen action affects the growth of the gland, its morphology, and regulation of protein expression. Endocrine therapy of non-organ-confined tumors is based on the androgen dependence of the vast majority of prostatic carcinomas. Although initial response rates are high, this therapy is only temporarily effective. Critical molecular changes ultimately resulting in androgen independence of tumor cells are unknown at this time. The androgen signal-transduction cascade and its central element, the androgen receptor (AR), are possible targets for such changes. Immunohistological analysis using anti-AR antibodies has revealed the presence of AR in a vast majority of therapy-responsive as well as therapy-unresponsive prostatic carcinomas, indicating that loss of AR expression is not the reason for androgen independence. On the other hand, molecular-biology studies have revealed qualitative and quantitative impairment of AR expression in prostatic tumor cell lines that represent very late stages of prostatic carcinoma development. Mutant ARs were detected in the prostatic tumor cell line LNCaP and in two specimens from primary prostatic tumors. The LNCaP mutant AR as well as mutant AR715met, one of the mutant receptors detected in tumor tissue, show a gain of function as compared with the wild-type receptor. In addition to androgens, the natural activators of the AR, the LNCaP receptor is activated also by progestagenic and estrogenic steroids and by the nonsteroidal antiandrogen flutamide. AR715met is activated by adrenal androgens and progesterone in addition to androgens.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗
PubMed1994

Laparoscopic retroperitoneal lymph node dissection for clinical stage I nonseminomatous testicular tumor.

OBJECTIVES: An appropriate laparoscopic technique for diagnostic retroperitoneal lymph node dissection in clinical Stage I testicular tumors is presented and its efficiency and morbidity are evaluated. METHODS: A two-step procedure has been developed. In the first step, a ventral approach is used. The colon is dissected free, then the spermatic vein is excised and the borders of dissection are defined. Via the ventral approach removal of retroaortic and retrocaval nodal tissue is technically not feasible. Therefore, in the second step, a lateral approach is used, which is the key to success because it permits straightforward transection of the lumbar vessels. Thus, complete lymph node dissection within the boundaries described by Weissbach can be achieved. Between August 1992 and March 1994, this procedure was performed in 15 patients. In 9 patients, the tumor was on the right side and in 6 it was on the left. RESULTS: Conversion to open surgery was necessary in 2 patients because of uncontrollable bleeding and a large metastasis. Microscopic metastasis were detected in 2 other patients. Apart from the bleeding just mentioned, no major complications occurred; no blood transfusions were required. CONCLUSIONS: The results obtained so far demonstrate that the technique is feasible and decreases postoperative morbidity. It therefore warrants further consideration.

Adult↗
PubMed1994

Clinical value of fructose 1,6 bisphosphatase in monitoring renal proximal tubular injury.

The usefulness of the gluconeogenic key enzyme fructose 1,6 bisphosphatase (FBPase), which is localized exclusively in the proximal nephron segment, as a marker compound to monitor injury of the proximal nephron segment during nephrotoxic therapy, was tested in a collective model of male patients treated for testicular cancer. These patients with normal kidney function were submitted to therapy with the nephrotoxic chemotherapeutics carboplatinum and a combination of cisplatinum, etoposide, bleomycin and ifosfamide. The release of FBPase activities into the urine was monitored during the initial two treatments over a period of eight days. The urinary enzyme activities measured were compared to the excretion of the "proximal tubular injury markers" N-acetyl-beta-D-glucosaminidase (NAG) and alpha 1-microglobulin (alpha 1m). The presence of glomerular damage was determined by measurement of urinary excretion rates of albumin (ALB) and IgG. In addition, protein excretion patterns following chemotherapy were monitored. The combined administration of cisplatin, etoposide and ifosfamide resulted in a pronounced proximal tubular injury as shown by the release of FBPase into the urine. This is substantiated by simultaneously increased excretion rates for NAG and alpha 1m. Proximal tubular toxicity was found to be less severe when cisplatin was combined with etoposide and bleomycin and was nearly absent following carboplatinum monotherapy. Carboplatinum only affected glomerular function and resulted in an elevated ALB and IgG excretion. From this model investigation it can be delineated that determination of urinary FBPase activities ensures a sensitive and reliable identification of proximal nephron damage.

Acetylglucosaminidase↗
PubMed1994

[Laparoscopic retroperitoneal lymph node excision in clinical stage I non-seminomatous testicular cancer].

Modified retroperitoneal lymph node dissection for stage I testicular tumors has been described by Weissbach. For performing laparoscopic retroperitoneal lymphadenectomy within these boundaries, we have developed a two-step procedure. In the first step, a ventral approach is used. The colon is dissected free, then the spermatic vein is excised, and the borders of dissection are defined. Removal of retroaortic and retrocaval nodal tissue is technically not feasible from the ventral approach. Therefore, in the second step, a lateral approach is employed, which is the key to success since it allows for easy transection of the lumbar vessels. Thus complete lymph node dissection can be realized. Between August 1992 and June 1993 this procedure was performed in 11 patients. In 7 patients, the tumor was on the right side and in 4 on the left. Conversion to open surgery was necessary in two patients because of uncontrollable bleeding and a large metastasis, respectively. Microscopic metastases were detected in two other patients. No major complications occurred; no blood transfusions were required. So far, the results have been encouraging.

Adult↗
PubMed1993

DNA sequence of the androgen receptor in prostatic tumor cell lines and tissue specimens assessed by means of the polymerase chain reaction.

Essentially all prostatic carcinomas relapse to an androgen-independent stage during androgen ablation therapy. The underlying genetic changes are still unclear. Such changes are suspected to affect the androgen-signalling pathway as well as growth promoting and inhibiting factors. This study was undertaken to test for structural changes of the androgen receptor in prostatic tumor cell lines and primary tumors. Complementary DNA (cDNA) fragments of the androgen receptor (AR) were isolated from the cell lines LNCaP, PC-3, and DU 145, ten tissue specimens obtained by radical prostatectomy, and five fine-needle biopsies by means of the polymerase chain reaction (PCR) technique. Fragments encoding the hormone- and DNA-binding domains were analyzed by DNA sequencing. The PCR technique is highly sensitive and especially recommended for the analysis of small tissue samples, such as those obtained by fine-needle aspiration. No alterations were detected in the tissue specimens and the five fine-needle aspirates. In the three tumor cell lines that represent late stages of prostatic tumor, different findings were obtained. The androgen-independent DU 145 cells did not express androgen receptors, whereas the PC-3 cells, which are also androgen-independent, expressed very low levels of normal AR. In contrast to this, the androgen-dependent LNCaP cells expressed high levels of structurally abnormal androgen receptors. These results suggest that androgen receptor mutations are probably uncommon molecular events in the early stages of prostatic cancer. Qualitative and quantitative changes, however, seem to occur in advanced prostatic cancer.

Base Sequence↗
PubMed1993

Modified retroperitoneal lymphadenectomy for testicular tumor: anatomical approach, operative technique and results.

Between January 1988 and June 1992, 56 patients underwent nerve-preserving retroperitoneal lymphadenectomy at the Department of Urology, University of Innsbruck. In 23 patients stage I, and in 33 patients stage II testicular tumors were found (staging according to the criteria recommended in Lugano 1979). Orchiectomy and subsequent lymphadenectomy within the boundaries described by Weissbach's group were performed for stage I tumors. In patients presenting with stage IIa or IIb tumors modified retroperitoneal lymphadenectomy within the boundaries suggested by Colleselli's group was performed. In stage IIc patients the residual tumor was resected after three cycles of polychemotherapy. If possible, nerve-sparing lymphadenectomy was performed. By adapting the operative technique to the respective tumor stage antegrade ejaculation could be preserved in 47 of these 56 patients. Semen analysis was carried out in 22 patients. The results in patients with stages I and IIa tumors were excellent, while in stages IIb and IIc patients' exocrine testicular function was considerably worse due to inductive polychemotherapy. None of the patients had a retroperitoneal recurrence. Of all 56 patients only one had a relapse in the lung (1.7%). The average follow-up period was 29 months.

Adolescent↗