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Biomedical subjects

E Saksela

Publications and source records attributed to E Saksela.

At least 19 recordsLinked to original sources
PubMed2004

Consistency of staining and reporting of oestrogen receptor immunocytochemistry within the European Union--an inter-laboratory study.

To assess the variability of oestrogen receptor (ER) testing using immunocytochemistry, centrally stained and unstained slides from breast cancers were circulated to the members of the European Working Group for Breast Screening Pathology, who were asked to report on both slides. The results showed that there was almost complete concordance among readers (kappa=0.95) in ER-negative tumours on the stained slide and excellent concordance among readers (kappa=0.82) on the slides stained in each individual laboratory. Tumours showing strong positivity were reasonably well assessed (kappa=0.57 and 0.4, respectively), but there was less concordance in tumours with moderate and low levels of ER, especially when these were heterogeneous in their staining. Because of the variation, the Working Group recommends that laboratories performing these stains should take part in a external quality assurance scheme for immunocytochemistry, should include a tumour with low ER levels as a weak positive control and should audit the percentage positive tumours in their laboratory against the accepted norms annually. The Quick score method of receptor assessment may also have too many categories for good concordance, and grouping of these into fewer categories may remove some of the variation among laboratories.

Breast Neoplasms↗
PubMed2002

Tumour microvessel density as predictor of chemotherapy response in breast cancer patients.

The aim of this study was to evaluate the predictive value of intratumoural microvessel density in breast cancer. We studied immunohistochemically primary tumours of 104 patients with metastasised breast cancer who took part in a randomised multicentre trial comparing docetaxel to sequential methotrexate and 5-fluorouracil. Vessels were highlighted with factor VIII staining and counted microscopically. Microvessel density was compared with clinical response to chemotherapy and patient survival. The microvessel density of the primary tumour was not significantly associated with patient's response to chemotherapy, time to progression or overall survival in the whole patient population or in the docetaxel or methotrexate and 5-fluorouracil groups. However, disease-free survival was longer in patients with low microvessel density (P=0.01). These findings suggest that microvessel density of the primary tumour cannot be used as a predictive marker for chemotherapy response in advanced breast cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2002

C-erbB-2 expression does not predict response to docetaxel or sequential methotrexate and 5-fluorouracil in advanced breast cancer.

Breast cancer patients with c-erbB-2-positive tumours seem to benefit from anthracycline-based adjuvant chemotherapy. The predictive value of c-erbB-2 for taxane sensitivity is not yet clear. The purpose of this study was to assess whether c-erbB-2 expression is associated with clinical sensitivity to docetaxel (T) or sequential methotrexate and 5-fluorouracil (MF). A total of 283 patients with metastatic breast cancer were initially enrolled in a randomised multicentre trial comparing docetaxel with sequential MF in advanced breast cancer. Paraffin-embedded blocks of the primary tumour were available for 131 patients (46%). c-erbB-2 status was determined by immunohistochemistry using a polyclonal antibody to the c-erbB-2 protein. C-erbB-2 expression was scored in a semi-quantitative fashion using a 0 to 3+ scale. Staining scores 2+ or greater were considered positive. Response evaluation was performed according to World Health Organization (WHO) recommendations. Overall 54 (42%) patients had c-erbB-2-positive tumours. There was no association between treatment outcome and c-erbB-2 overexpression. The overall response rates (RR) (n=128) among c-erbB-2-negative and -positive patients were 35 and 44%, respectively (P=0.359). In the MF arm (n=62), the RR was somewhat higher in the c-erbB-2 overexpressors (33% versus 18%, P=0.18). In the docetaxel arm the RRs were very similar, regardless of the c-erbB-2 expression (53% versus 53%). While several studies have suggested a prognostic and putative predictive significance of c-erbB-2 overexpression in early breast cancer, the significance of c-erbB-2 expression as a predictive factor for response to various cytotoxic treatments in advanced breast cancer is still controversial. In this study, c-erbB-2 expression could not predict response to either MF or T. Thus, tumours over-expressing c-erbB-2 are not uniformly more sensitive to taxanes and c-erbB-2 expression cannot yet be applied clinically as a predictive factor for response in advanced breast cancer.

Adolescent↗
PubMed2000

Predictive value of p53, mdm-2, p21, and mib-1 for chemotherapy response in advanced breast cancer.

p53 is a transcription factor that participates in cell cycle checkpoint processes and apoptosis. The protein product of the murine double minute gene 2 (mdm-2) plays a central role in the regulation of p53. In response to DNA-damaging agents, the wild-type p53-activated fragment 1 (WAF1 also known as p21) is an important downstream effector in the p53-specific growth arrest pathway. In breast cancer patients, it is unclear whether measuring p53, mdm-2, or p21 expression provides information on how patients will respond to chemotherapy. Mib-1 monoclonal antibody recognizes the proliferation-related antigen Ki-67. High tumor proliferation has previously been associated with response to chemotherapy. p53, mdm-2, p21, and mib-1 expression were assessed by immunohistochemical methods in primary tumors derived from 134 patients who took part in a randomized multicenter trial comparing docetaxel to sequential methotrexate and 5-fluorouracil (MF) in advanced breast cancer. Low mib-1 staining correlated with negative p53 staining (P = 0.001), and mdm-2 and p21 stainings correlated positively with each other (P < 0.001). p53, mdm-2, p21, and mib-1 expression were not significantly associated with response to chemotherapy, time to progression, or overall survival in the whole patient population or in the docetaxel group. However, in the MF group, a low mib expression (<25%) and a high mdm-2 expression (> or =10%) predicted a better response (P = 0.014 and P = 0.046, respectively) to treatment and a longer time to progression in both univariate and multivariate analyses. p53 staining status was not associated with response to treatment in either group. Interestingly, tumors with both negative mdm-2 and p21 expression, irrespective of p53 status, had a high response rate to docetaxel but no response to MF. Although highly preliminary, the findings suggest that different tumor biological factors may predict response to different chemotherapy regimens with distinct mechanisms of action. The results of our phenotype analysis also indicate that it is more likely that a panel of tumor biological factors instead of only one single factor may be needed for better prediction of chemotherapy response.

Adolescent↗
PubMed1999

c-Myc and E1A induced cellular sensitivity to activated NK cells involves cytotoxic granules as death effectors.

The contact of natural killer (NK) cells with foreign cells and with certain virus-infected or tumor cells triggers the cytolytic machinery of NK cells. This triggering leads to exocytosis of the cytotoxic NK cell granules. The oncoproteins c-Myc and E1A render cells vulnerable to NK cell mediated cytolysis yet the mechanisms of sensitization are not well understood. In a model where foreign cells (rat fibroblasts) were cocultured with human IL-2 activated NK cells, we observed that NK cells were capable of efficiently killing their targets only if the cells overexpressed the oncogene c-Myc or E1A. Both the parental and the oncogene expressing fibroblasts similarly triggered phosphoinositide hydrolysis in the bound NK cells, demonstrating that NK cells were cytolytically activated in contact with both resistant parental and oncogene expressing sensitive target fibroblasts. The cell death was independent of wild-type p53 and was not inhibited by an anti-apoptotic protein EIB19K. These results provided evidence that c-Myc and E1A activated the NK cell induced cytolysis at a post-triggering stage of NK cell-target cell interaction. In consistence, the c-Myc and E1A overexpressing fibroblasts were more sensitive to the cytolytic effects of isolated NK cell-derived granules than parental cells. The data indicate that oncogenes activate the cytotoxicity of NK cell granules. This mechanism can have a role in directing the cytolytic action of NK cells towards the virus-infected and cancer cells.

Actins↗
PubMed1997

Induction of TNF-sensitive cellular phenotype by c-Myc involves p53 and impaired NF-kappaB activation.

Normal fibroblasts are resistant to the cytotoxic action of tumor necrosis factor (TNF), but are rendered TNF-sensitive upon deregulation of c-Myc. To assess if oncoproteins induce the cytotoxic TNF activity by modulating TNF signaling, we investigated the TNF-elicited signaling responses in fibroblasts containing a conditionally active c-Myc protein. In association with cell death, c-Myc impaired TNF-induced activation of phospholipase A2, JNK protein kinase and cell survival-signaling-associated NF-kappaB transcription factor complex. The TNF-induced death of mouse primary fibroblasts expressing deregulated c-Myc was inhibited by transient overexpression of the p65 subunit of NF-kappaB, which increased NF-kappaB activity in the cells. Unlike other TNF-induced signals, TNF-induced accumulation of the wild-type p53 mRNA and protein was not inhibited by c-Myc. TNF, with c-Myc, induced apoptosis in mouse primary fibroblasts but only weakly in p53-deficient primary fibroblasts. The C-terminal domain of p53, which is a transacting dominant inhibitor of wild-type p53, failed to inhibit apoptosis by c-Myc and TNF, suggesting that the cell death was not dependent on the transcription-activating function of p53. Taken together, the present findings show that the cytotoxic activity of TNF towards oncoprotein-expressing cells involves p53 and an impaired signaling for survival in such cells.

3T3 Cells↗
PubMed1995

Activation of natural killer cell migration by leukocyte integrin-binding peptide from intracellular adhesion molecule-2 (ICAM-2).

Intracellular adhesion molecule-2 (ICAM-2), one of the ligands of CD11a/CD18 (LFA-1), is mainly expressed on endothelial and hematopoietic cells. The biological significance of ICAM-2 has remained unclear. Previous findings have shown that a peptide from ICAM-2, spanning residues 21-42 from the first immunoglobulin domain, enhances natural killer (NK) cell cytotoxicity and induces T cell aggregation. We have now studied the effect of the same ICAM-2 peptide on NK cell migration in the Boyden chamber assay. The peptide significantly increased NK cell migration up to 215 +/- 21%, as compared to migration of control cells (100%), and the induction was inhibited by anti-CD11a monoclonal antibodies. The ICAM-2 peptide also induced polymerization of F-actin at the leading edge of migratory NK cells. Cross-linking of CD11a/CD18 receptors with anti-CD11a or anti-CD18 monoclonal antibodies and secondary antibodies resulted in receptor recycling, increased migration, and actin polymerization, but led to slight inhibition of cytotoxicity. The ICAM-2 peptide did not induce such a receptor recycling. Phosphotyrosine immunoblotting experiments showed that the ICAM-2 peptide increased the phosphorylation of 150- and 35-kDa proteins. During cross-linking with antibodies, only the 150-kDa protein showed increased phosphorylation. The results show that depending on the type of CD11a/CD18 receptor ligation different kinds of signals are transduced in NK cells. These signals may either trigger only locomotion, or both locomotion and cytotoxicity. Based on these findings, a major function for ICAM-2 on endothelium may be triggering of migration of adhering leukocytes.

Actins↗
PubMed1994

c-Myc induces cellular susceptibility to the cytotoxic action of TNF-alpha.

Tumor necrosis factor-alpha (TNF) is a multifunctional cytokine which is cytotoxic for some tumor cells and transformed cells. The molecular mechanisms which render transformed and tumor cells sensitive to the cytotoxic action of TNF are unclear. We show here that an increased expression of the c-Myc oncoprotein strongly increases cellular sensitivity to TNF cytotoxicity. In Rat1A fibroblasts, which are resistant to TNF, the addition of TNF with a concomitant activation of a hormone-inducible c-Myc-estrogen receptor chimera (MycER) resulted in apoptotic cell death. Similarly, c-Myc overexpression enhanced the sensitivity of NIH3T3 fibroblasts to TNF-induced death. The c-Myc and TNF-induced apoptosis was inhibited by ectopic expression of the Bcl2 oncoprotein and by the free oxygen radical scavenging enzyme Mn superoxide dismutase. Furthermore, in highly TNF-sensitive fibrosarcoma cells, antisense c-myc oligodeoxynucleotides caused a specific inhibition of TNF cytotoxicity. Our results suggest that the deregulation of c-Myc, which is common in human tumors and tumor cell lines is one reason why these cells are TNF sensitive.

3T3 Cells↗
PubMed1994

Characterization of the E-selectin ligand on NK cells.

In this study we demonstrate that human CD56+CD16+/CD3- NK cells adhere to the E-selectin expressed by stimulated HUVEC in a sialidase- and Ca(2+)-dependent manner, and express a silylated Lex adhesion structure. We have characterized this sLe(x) epitope on NK cell in detail and show here that the sLe(x) on NK cells was not recognized by the CSLEX1 Ab, but was readily identified by two anti-di-sLe(x) Abs, KM-93 and FH-6. Furthermore, cleaving sialic acid with a sialidase treatment revealed a pool of Le(x) epitopes on the NK cells surface, providing further proof that NK cells express sLe(x) epitopes. Extensive protease treatments did not cleave the sLe(x) epitope from NK cells, which suggests that it could be linked to a lipid backbone. This di-sLe(x) was able to mediate adhesion to E-selectin, suggesting that it represents an essential part or is closely related to a selectin ligand on NK cells. We were also able to show that NK cells possess several alpha 2,3 sialyltransferases and alpha 1,3 or alpha 1,3/4 fucosyltransferases. These enzymes are crucial in the synthesis of sLe(x) epitopes on cell surfaces. Taken together, we provide evidence that NK cells have a di-sLe(x) oligosaccharide capable of adhesion to E-selectin, and NK cells have the machinery (i.e., relevant transferases) to generate these sialylated Lewis oligosaccharides.

Calcium↗
PubMed1994

Stimulated natural killer cells secrete factors with chemotactic activity, including NAP-1/IL-8, which supports VLA-4- and VLA-5-mediated migration of T lymphocytes.

In vivo, natural killer (NK) cells dominate among the early invading cells in allografts and virus-infected tissues, and they are followed later by an influx of T cells. The same sequence of events was seen in our modified Boyden chamber assay. The migration of both CD3+/CD4+ and CD3+/CD8+ cells through fibronectin-coated filters increased after co-culture with NK cells. The migratory response to a soluble factor from NK cells supernatants was predominantly chemotactic rather than chemokinetic. Endogenous NK cells, purified in the presence of human serum albumin, did not induce T cell chemotaxis, but NK cells which were purified in the presence of 10% fetal calf serum (FCS), or which were activated in the absence of FCS with 10(-4) M histamine, with 300 IU/ml interleukin (IL)-2, or with a combination of 10 IU/ml IL-2 and 10 micrograms/ml CD16 monoclonal antibody increased T cell migration by 30-70%. Both the random and chemotactic migration were dependent on fibronectin receptors VLA-4 and VLA-5 on T cells. About 60% of the chemotactic was neutralized by NAP-1/IL-8 polyclonal antibody. Northern blot analysis revealed IL-8 mRNA expression in highly purified, stimulated NK cells; dimeric IL-8 protein secreted by NK cells was detected by immunoblotting, and, in immunofluorescence staining IL-8 was visualized in NK cells. These observations suggest that NK cells, early invaders in the foci of injury, participate in the initiation of a specific immune response by facilitating T cell recruitment.

Cell Adhesion↗