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Biomedical subjects

J Hansson

Publications and source records attributed to J Hansson.

At least 37 records · Page 2Linked to original sources
PubMed2001

The MEK1 inhibitor PD98059 sensitizes C8161 melanoma cells to cisplatin-induced apoptosis.

The regulation of apoptosis is believed to be dependent on the balance of the activities of different intracellular signalling systems. Activation of the SAPK/JNK pathway is implied in pro-apoptotic signalling, while activation of the MEK1/ERK pathway may have a viability-promoting effect. We show here that treatment with the MEK1 inhibitor PD98059 sensitizes the human melanoma cell line C8161 to cisplatin-induced apoptosis. In these cells, cisplatin at 40 microM did not elicit significant cell death, whereas massive cell death was seen when cells were pretreated for 20 h with 40 microM PD98059 before the addition of cisplatin. Concomitant addition of PD98059 and cisplatin did not have any sensitizing effect, and PD98059 on its own did not induce apoptosis. However, in three other human melanoma cell lines PD98059 did not potentiate cisplatin-induced apoptosis. Instead, in one of these cell lines (AA), PD98059 protected against cisplatin-induced cytotoxicity. We conclude that blocking of the MEK1/ERK pathway may, in some instances, potentiate the cytotoxic effect of cisplatin on human melanoma cell lines, whereas in other instances it may have a protective effect. Thus it cannot be regarded as a general approach to sensitizing melanoma cells to drug-induced apoptosis.

Antineoplastic Agents↗
PubMed2001

Cisplatin induces the proapoptotic conformation of Bak in a deltaMEKK1-dependent manner.

In a panel of four human melanoma cell lines, equitoxic doses of cisplatin induced the proapoptotic conformation of the Bcl-2 family protein Bak prior to the execution phase of apoptosis. Because cisplatin-induced modulation of the related Bax protein was seen in only one cell line, a degree of specificity in the signal to Bak is indicated. Little is known about upstream regulation of Bak activity. In this study, we examined whether the apoptosis-specific pathway mediated by a kinase fragment of MEKK1 (DeltaMEKK1) is involved in the observed Bak modulation. We report that expression of a kinase-inactive fragment of MEKK1 (dominant negative MEKK [dnMEKK]) efficiently blocked cisplatin-induced modulation of Bak and cytochrome c release and consequently also reduced DEVDase activation and nuclear fragmentation. Accordingly, expression of a kinase-active MEKK1 fragment (dominant positive MEKK) was sufficient to induce modulation of Bak in three cell lines and to induce apoptosis in two of these. dnMEKK did not block cisplatin-induced c-Jun N-terminal kinase (JNK) activation, in agreement with a specifically proapoptotic role for the DeltaMEKK1 pathway. Finally, we show that reduction of Bak expression by antisense Bak reduced cisplatin-induced loss of mitochondrial integrity and caspase cleavage activity in breast cancer cell lines. In summary, we have identified Bak as a cisplatin-regulated component downstream in a proapoptotic, JNK-independent DeltaMEKK1 pathway.

Antineoplastic Agents↗
PubMed2000

CDKN2A germ-line mutations in individuals with multiple cutaneous melanomas.

Germ-line CDKN2A mutations are present in some kindreds with hereditary cutaneous melanoma, and in Sweden a founder mutation with an extra arginine in codon 113 (113insR) has been identified. We screened 80 individuals with at least two primary cutaneous melanomas, who were identified mainly by a search of a regional cancer registry, for germ-line CDKN2A mutations. In nine patients, CDKN2A alterations that may contribute to melanoma predisposition were detected. In six individuals with a family history of melanoma, the 113insR founder mutation was present. One patient, who also had a family history of melanoma, had a 24-bp deletion that included codons 62-69. An in vitro binding assay established that the resulting mutant p16 protein was unable to bind cyclin-dependent kinase 4 and cyclin-dependent kinase 6. Two patients without a family history of melanoma had CDKN2A alterations: (a) one had a mutation in the 5' noncoding sequence (-14C/T); and (b) the other had an insertion of an extra T in codon 28, which results in a stop signal in codon 43. The median age at diagnosis of the first melanoma was significantly lower, the number of primary melanomas was significantly higher, and the presence of a family history of melanoma was significantly more common in patients with CDKN2A mutations than in those without germ-line mutations. The proportion of CDKN2A mutation carriers was significantly higher among patients treated for three or more primary melanomas compared with those with two tumors only. We conclude that mutation screening of individuals with multiple primary melanomas is a useful strategy to identify new melanoma kindreds with CDKN2A germ-line mutations.

Adolescent↗
PubMed2000

Hereditary cutaneous melanoma.

Members of some kindreds have a hereditary predisposition for development of cutaneous melanoma. Cytogenetic and linkage studies implicated chromosomes 1p and 9p as possible locations for genetic alterations predisposing for melanoma. Germline mutations in the CDKN2A gene on chromosome 9p21 have been identified in hereditary melanoma, but are present in only approximately 40% of kindreds with linkage to 9p21, indicating that changes in other gene(s) at this location may also predispose to melanoma. In a few families, germline mutations in the CDK4 gene are present. The genetic alterations underlying disease predisposition in a large proportion of melanoma families remain unknown.

Chromosome Mapping↗
PubMed2000

Expression and characterization of trypsinogen produced in the human male genital tract.

Trypsinogen is a serine proteinase produced mainly by the pancreas, but it has recently been found to be expressed also in several cancers such as ovarian and colon cancer and in vascular endothelial cells. In this study, we found that trypsinogen-1 and -2 are present at high concentrations (median levels, 0.4 and 0.5 mg/L, respectively) in human seminal fluid and purified them to homogeneity by immunoaffinity and anion exchange chromatography. Purified trypsinogen isoenzymes displayed a M(r) of 25 to 28 kd in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. Most of the trypsinogen-1 purified from seminal fluid was enzymatically active whereas trypsinogen-2 occurred as the proform, which could be activated by enteropeptidase in vitro. Immunohistochemically, trypsinogen protein was detected in the human prostate, urethra, utriculus, ejaculatory duct, seminal vesicles, deferent duct, epididymal glands, and testis. Expression of trypsinogen mRNA in the same organs was demonstrated by in situ hybridization. Trypsinogen mRNA was also detected in the prostate and seminal vesicles by reverse transcriptase-polymerase chain reaction and Northern blotting. Isolated trypsin was shown to activate the proenzyme form of prostate-specific antigen. These results suggest that trypsinogen isoenzymes found in seminal fluid are produced locally in the male genital tract and that they may play a physiological role in the semen.

Blotting, Northern↗
PubMed2000

Quality in health care. Medical or managerial?

Explores the notion that the introduction of total quality management (TQM) in the public health-care sector indicates a conceptual break with a tradition in which the authority to define and interpret the meaning of medical practice has been located solely within the medical profession. It also serves to shift the focus of medical practice away from its contextual and interactional character towards numerical representations and codification in monetary terms. Further, it is argued that the realization of management ideals in everyday practice is dependent more on the availability of pre-existing technologies and standard procedures than on the ingenuity of particular organizational and institutional actors. These arguments are illustrated with the reutilization for TQM purposes of "local incident reports" in a Swedish hospital organization.

Hospitals, Public↗
PubMed2000

Bladder cancer: allelic deletions at and around the retinoblastoma tumor suppressor gene in relation to stage and grade.

Inhibition of the retinoblastoma tumor suppressor gene (RB) is probably important in the pathogenesis of urinary bladder cancer. Little information is available concerning allelic loss on 13q11 to 13q32 and its relation to grade and stage. In a population-based study, freshly frozen tissue was collected from all new cases of urinary bladder cancer in the Stockholm region during 1995-1996. Here we report the occurrence of loss of heterozygosity (LOH) at seven sites in 13q11 to 13q32 as analyzed in 236 cases by a fluorescent multiplex PCR-based on tumor DNA and peripheral blood. For each site, about 30% of the cases were not informative because of homozygosity. Replication errors were detected in 4% (17 cases). LOH was found in 21 (at 13q11-12.1) to 32% (at 13q14.3 in RB) of the informative cases. A correlation was found between the prevalence of LOH at all observed loci and stage and grade, respectively, and it was statistically significant for 13q14.3. LOH at RB was found in Ta as well as grade 1 tumors. Also, a statistically significant correlation was found between the number of loci with LOH at 13q and tumor stage and grade, respectively. Typically an altered RB function is related to the expected clinical course of urinary bladder cancer, but allelic loss including the gene also occurs in low grade and low stage tumors. An altered RB function probably is not necessary for a malignant transformation of urothelial cells. The causal direction of the relation between the quantity of the deleted DNA and tumor aggressiveness is not clear.

Alleles↗
PubMed1999

Melanoma development in relation to non-functional p16/INK4A protein and dysplastic naevus syndrome in Swedish melanoma kindreds.

The CDKN2A gene encodes the cell cycle inhibitor p16/ INK4A, which is involved in familial cutaneous melanoma. We have studied five Swedish familial melanoma kindreds characterized by germline mutations in CDKN2A and dysplastic naevus syndrome (DNS). We found significant correlations between germline CDKN2A mutations and melanoma and between DNS phenotype and melanoma, respectively. There was also a correlation between mutation status and the presence of DNS. In CDKN2A mutation carriers, all cases of early-onset melanoma occurred in DNS individuals, and the mean age at melanoma diagnosis was significantly lower in individuals with DNS than in those without a confirmed DNS phenotype. In one family where the proband had a P48L mutation in CDKN2A exon 1, the DNS phenotype was studied in detail. In vitro binding experiments established that the P48L mutant protein does not bind to cdk4 or cdk6 and thus is functionally abnormal. Furthermore, we demonstrated loss of heterozygosity at markers on chromosome 9p flanking the CDKN2A locus in a primary melanoma and a metastasis from the proband. Our results are consistent with the hypothesis that germline CDKN2A mutations and DNS both contribute to the predisposition to melanoma and may lead to the development of early-onset melanoma when present in the same individual.

Chromosomes, Human, Pair 9↗
PubMed1998

Screening of germline mutations in the CDK4, CDKN2C and TP53 genes in familial melanoma: a clinic-based population study.

Germline mutations within the CDKN2A gene, coding for the cyclin-dependent kinase inhibitor p16, have been detected by screening in 8% of Swedish families with an inheritance of cutaneous melanoma (FMM) and dysplastic nevus syndrome (DNS). Contrastingly, the closely related gene CDKN2B had no disease-related mutations in these families. A majority of Swedish families with hereditary melanoma predisposition thus lack germline mutations in these cell cycle G1 checkpoint-regulating genes. Additional genes with the potential to contribute to increased melanoma risk may code for related components of the cell cycle-regulating machinery. The gene for cyclin-dependent kinase 4, CDK4, has been found in mutated form in the germline from individuals belonging to 2 melanoma kindreds in the United States. The CDKN2C gene coding for the cyclin-dependent kinase inhibitor p18 is localized on 1p32, a region frequently involved in chromosomal changes in melanomas and other tumors. The TP53 suppressor gene, involved in cell cycle regulation and maintenance of genetic stability, is found mutated in the germline of patients with hereditary Li-Fraumeni syndrome, leading to early onset of several human cancers, including melanoma. The present investigation reports the results of screening the 100 Swedish melanoma families for germline mutations in the CDK4, CDKN2C and TP53 genes. No disease-related mutations were detected in the coding regions. A direct contribution of these genes to the hereditary risk for melanoma in members of Swedish melanoma kindreds therefore appears unlikely.

Base Sequence↗
PubMed1998

Perforin and IFN-gamma are involved in the antitumor effects of antibody-targeted superantigens.

The bacterial superantigen staphylococcal enterotoxin A (SEA) is a potent inducer of cytokine production and cytotoxic T cell responses. To target a T cell attack against tumor cells we have genetically engineered a fusion protein of SEA and the Fab part of the tumor-reactive mAb C215. Injection of this Fab-SEA fusion protein to mice carrying lung metastases of the poorly immunogenic B16 melanoma transfected with the C215 Ag resulted in infiltration of cytokine-producing T cells, perforin-containing CTL, and a marked tumor elimination. Fab-SEA therapy induced substantial levels of IFN-gamma and TNF-alpha in serum. In the present study we have characterized the molecular mechanisms of the antitumor effect induced by Fab-SEA treatment in vivo. Neutralization of cytokines by specific Abs demonstrated a major role for IFN-gamma in the suppression of tumor growth. In addition, a minor contribution of TNF-alpha was recorded. Injections of Fab-SEA into normal mice induced strong CTL activity but failed to promote cytotoxic function in perforin knockout mice. Also, a markedly reduced therapy was noted in perforin knockout mice, implicating a role for CTL in Fab-SEA-mediated tumor eradication. The data suggest that Fab-SEA-targeted T cells may suppress tumor growth by both perforin-dependent cytotoxicity and local release of cytokines such as IFN-gamma. The latter mechanism may have an important role in cytostatic effects against Ag-negative bystander tumor cells.

Animals↗
PubMed1998

Repeated treatment with antibody-targeted superantigens strongly inhibits tumor growth.

Superantigens (SAg) are microbial proteins with the capacity to activate a large proportion of T cells. We have developed a novel approach for cancer immunotherapy by genetically fusing the SAg staphylococcal enterotoxin A (SEA) to a Fab-fragment of a tumor-specific antibody. Repeated exposure to SEA induces a state of unresponsiveness including cell deletion and functional hyporesponsiveness, i.e., anergy. In this study we have developed improved therapeutic schedules to allow repeated injections of Fab-SEA, limit development of immunological unresponsiveness and promote maximal anti-tumor response. Four daily injections of Fab-SEA to mice carrying B 16-C215 lung metastases resulted in 90-95% reduction in the number of metastases. However, the animals did retain a minimal residual tumor disease. The immune system was in a hyporesponsive state after 4 daily Fab-SEA injections, and further injections did not improve therapy. Two repeated cycles, each comprising 4 daily injections of Fab-SEA, significantly prolonged the survival and resulted in complete cure of a fraction of the animals. A rest period of 10 days between the cycles was required to mount an efficient secondary anti-tumor response. This secondary immune response was characterized by partial recovery of cytokine production i.e., interleukin-2, interferon-gamma and tumor necrosis factor-alpha. Strong CTL activity was detected in animals that had rested for 8 weeks between the 2 cycles. Interestingly, irrespective of the resting period, the CD4+ SEA-reactive T cells expanded in response to all 4 additional Fab-SEA injections both locally and in spleen. In contrast, only marginal expansion of CD8+ T cells was seen if restimulation was given within 1 month. Our data show that potent anti-tumor effector functions can be induced after repeated stimulation cycles with a SAg-monoclonal antibody fusion protein resulting in a CD4+ T cell-dependent cytokine release, prolonged survival and induction of complete cures.

Animals↗
PubMed1998

In vivo induction of the interferon-stimulated protein 2'5'-oligoadenylate synthetase in tumor and peripheral blood cells during IFN-alpha treatment of metastatic melanoma.

Interferon-alpha (IFN-alpha) therapy induces a response in a proportion of patients with metastatic melanoma. However, the mechanism of the antitumor action and reason(s) for resistance to IFN therapy are not known. To investigate whether lack of clinical response may be due to resistance of the melanoma cells to IFN-alpha or to an inability of IFN-alpha to reach the tumor cells during treatment, we investigated the in vivo and in vitro susceptibility of primary tumor cells obtained through fine needle aspiration biopsies and peripheral blood mononuclear cells (PBMC) to the induction of the IFN-induced enzyme 2'5'-oligoadenylate synthetase (2'5'OAS) during initiation of IFN-alpha therapy in 10 patients with metastatic melanoma. None of the patients showed an objective response to IFN-alpha treatment. The melanoma cells from 2 of the 10 patients were resistant to IFN-induced enhancement of 2'5'OAS in vitro. This correlated well with the in vivo induction of 2'5'OAS in the malignant cells, as no in vivo induction was seen in the 2 patients whose malignant cells were resistant in vitro, whereas tumor cells from 7 of 8 of the remaining patients showed enhancement also in vivo. This study shows that it is possible to monitor the cellular susceptibility of tumor cells to IFN-alpha in vivo and that melanoma cells from a small percentage of patients are resistant to the cellular effects of IFN-alpha. Furthermore, the absence of a clinical response to IFN-alpha therapy in the majority of melanoma patients can be explained neither by impaired cellular susceptibility to IFN nor by an inability of IFN-alpha to reach the tumor.

2',5'-Oligoadenylate Synthetase↗
PubMed1997

Screening of germline mutations in the CDKN2A and CDKN2B genes in Swedish families with hereditary cutaneous melanoma.

BACKGROUND: Approximately 10% of human cutaneous melanomas occur in families in which several members are affected. The familial predisposition to this disease is often associated with dysplastic nevus syndrome, a condition in which afflicted family members have multiple dysplastic nevi (atypical moles). The chromosome region 9p21 and markers on chromosomes 1p and 6p have been linked to melanoma susceptibility. The tumor suppressor genes CDKN2A and CDKN2B have been mapped to the 9p21 region, and genetic analyses have revealed the presence of germline CDKN2A alterations in melanoma families. The reported frequencies of such alterations, however, vary among these families. PURPOSE: The present investigation was carried out to determine the frequencies of CDKN2A and CDKN2B germline gene mutations among members in a population-based cohort of Swedish melanoma families (i.e., melanoma kindreds). METHODS: DNA was prepared from blood samples obtained from 181 individuals belonging to 100 melanoma kindreds. The polymerase chain reaction (PCR) technique, followed by single-strand conformation polymorphism (SSCP) and nucleotide sequence analyses, were used to identify the types and frequencies of mutations in exons 1, 1beta, 2, and 3 of the CDKN2A gene and in exons 1 and 2 of the CDKN2B gene. RESULTS: CDKN2A gene aberrations were independently identified by both SSCP and nucleotide-sequence analyses. Nucleotide-sequence analysis identified a single point mutation leading to a substitution of leucine for proline in codon 48 of exon 1 in a family with a history of melanoma and several other cancers. A second abnormality, leading to an insertion of an extra arginine residue at codon number 113 of exon 2, was seen in four separate families. The CDKN2A exon-3 coding region had the wild-type sequence in all samples. No germline mutations were found in the alternative exon 1beta of the CDKN2A gene or in exons 1 and 2 of the CDKN2B gene. CONCLUSIONS: The present investigation demonstrates that CDKN2A germline gene mutations were observed in 7.8% of the 64 Swedish melanoma kindreds that each included at least two first-degree relatives with melanoma and dysplastic nevus syndrome. No CDKN2A exon 1beta or CDKN2B mutations were identified. The critical genes responsible for the inheritance of a susceptibility to develop melanoma among family members in this population have yet to be identified.

Carrier Proteins↗