Heike Knüpfer

Significance of interleukin-6 (IL-6) in breast cancer (review).

Cytokines are factors that are known to have both tumor-promoting and inhibitory effects on breast cancer growth depending presumably on their relative concentrations and the presence of other modulating factors. Different cytokines play an important role in controlling the immune system. Interleukin-6 (IL-6) is a pleiotropic cytokine with obviously tumor-promoting and tumor-inhibitory effects. Here, we review the role of IL-6 in in vitro experiments of breast tumor cells, in breast tumor tissues (BTs) and assess its potential as a prognostic indicator in breast cancer patients. A literature search was conducted using PubMed, restricted to articles published in English language. In summary, results regarding the effect of IL-6 on breast tumor cells and on BTs are not unique indicating both tumor-promoting and inhibitory effects of IL-6. Concerning patients’ serum IL-6 levels, data are surprisingly unique showing IL-6 to be a negative prognosticator in breast tumor patients.

Serum interleukin-6 levels in colorectal cancer patients--a summary of published results.

IntroductionIt is now clear that inflammation and cancer initiation and progression are linked. Interleukin-6 (IL-6) is a pleiotropic inflammatory cytokine with described cancer stimulatory and also cancer inhibitory properties. The study’s aim was to assess the potential of circulating IL-6 as a prognostic indicator in colorectal cancer.Materials and methodsA literature search was conducted using PubMed, restricted to articles published in English language. We compared published results in regard to differences in IL-6 levels between healthy controls and colon cancer patients (seven published results), between patients with increasing tumor stages (eight published results), between patients with differences in tumor size (four published results), and between patients with and without liver (three published results) or lung metastasis (one published result). Furthermore, we reviewed the literature in regard to the possible correlation of IL-6 levels with survival time (five published results) and correlation of IL-6 levels and lymph node involvement (three published results).ResultsConcerning colon tumors, results are consistent. Colon cancer patients reveal higher serum IL-6 levels than healthy controls. Furthermore, higher IL-6 levels are associated with increasing tumor stages and tumor size, with metastasis and decreased survival.ConclusionTherefore, circulating IL-6 might be prognostic indicator in colorectal cancer.

sIL-6R: more than an agonist?

On target cells, interleukin‐6 (IL‐6) interacts with its receptor complex consisting of the membrane‐bound IL‐6 receptor (IL‐6R) and the signal transducing protein gp130. IL‐6R can exist as a soluble protein (sIL‐6R), which binds the ligand IL‐6. This soluble complex can bind to gp130 on cells that lack the membrane‐bound IL‐6R and initiate signaling. This process is named transsignaling. The significance of transsignaling via sIL‐6R is underlined by different publications and exceeds very probably the significance of the membrane‐bound IL‐6R. It is the general assumption that sIL‐6R acts as an agonist in combination with IL‐6 resulting in an enhancement of the IL‐6 effects. In this article, we suppose ‘non‐agonistic’ properties. There are several publications that give reasons to speculate that sIL‐6R (a) has IL‐6‐antagonistic effects, (b) has orphan properties and (c) interacts with yet unknown binding partners different from IL‐6. Knowledge about additional properties of sIL‐6R will enlarge the biologic understanding of this molecule and might give an explanation for the sometimes contrasting effects of the cytokine IL‐6.

The serotonin transporter availability in untreated early-onset and late-onset patients with obsessive-compulsive disorder.

The pathogenetic role of central serotonin transporters (SERT) in obsessive-compulsive disorder (OCD) has been investigated in vivo by positron emission tomography (PET) or single-photon emission computed tomography (SPECT) studies with inconsistent results. This might reflect methodological differences but possibly also the pathophysiological heterogeneity of the disorder, i.e. the age at onset of OCD. The aim of our study was to compare SERT availability in patients with OCD to healthy controls (HC) taking into account the onset type, other factors and covariates (e.g. SERT genotype, age, depression level, gender). We studied 19 drug-naive OCD patients (36±13 yr, eight females) with early onset (EO-OCD, n=6) or with late onset (LO-OCD, n=13), and 21 HC (38±8 yr, nine females) with PET and the SERT-selective radiotracer [11C]DASB. Statistical models indicated that a variety of covariates and their interaction influenced SERT availability measured by distribution volume ratios (DVR). These models revealed significant effects of onset type on DVR with lower values in LO-OCD (starting at age 18 yr) compared to EO-OCD and HC in limbic (e.g. the amygdala), paralimbic brain areas (the anterior cingulate cortex), the nucleus accumbens and striatal regions, as well as borderline significance in the thalamus and the hypothalamus. The putamen, nucleus accumbens and hypothalamus were found with significant interaction between two SERT gene polymorphisms (SERT-LPR and VNTR). These findings suggest that late but not early onset of OCD is associated with abnormally low SERT availability. In part, functional polymorphisms of the SERT gene might determine the differences.

Lack of Knowledge: Breast Cancer and the Soluble Interleukin-6 Receptor

Background: Cytokines are and may be used as therapeutic targets in cancer therapy. In breast cancer, interleukin (IL)-6 is associated with different features of tumor biology like metastasis, certain stages, and decreased survival. It is now an established fact that signaling via the soluble IL-6 receptor (sIL-6R) (‘transsignaling’) is an important process in the IL-6 machinery. Methods and Results: In this mini-review, we discover that published knowledge about sIL-6R serum levels in breast cancer patients is sparse and, furthermore, most in vitro data merely show that tumor cells produce the sIL-6R endogenously. Conclusions: Therefore, a lot of research is still necessary to analyze the significance of the sIL-6R and therefore the transsignaling process in breast tumors. More knowledge about the sIL-6R in breast cancer would give insights into its putative role as blood marker of active tumor disease. Secondly, the sIL-6R may be useful in breast cancer as a new therapeutic pathway. If, as suggested by the literature, IL-6 mediates the aggressiveness and the growth of breast tumors, elevated circulating levels of IL-6 and its receptor may identify patients for whom the IL-6 complex is a therapeutic target.

Determinants of in vivo central serotonin transporter availability

Introduction/Aim: Serotonin transporter (SERT) imaging is widely applied for studying neuropsychiatric disorders such as major depression. However, covariates which influence SERT regulation in vivo have not yet been fully established. This is of upmost interest, since SERT study results are heterogeneous and genes and/or environment factors may have major impact. The aim of our study was therefore to investigate SERT availability measured with [C]DASB, epidemiological measures, as well as SERT gene polymorphisms (5-HTTLPR, VNTR) in healthy volunteers.

Neuroendocrinological correlates of stress responsiveness and in vivo central serotonin transporter availability

Introduction/Aim: Serotonin reuptake transporter (SERT)-inhibiting antidepressants (SRI) acutely stimulate cortisol and adrenocorticotrophic hormone (ACTH) secretion in healthy volunteers. They down-regulate hypothalamic–pituitary–adrenocortical (HPA) axis hyperactivity in depressed patients to normal levels. However, short-term effects of daily treatment with SRI on the dex/CRH test results are comparable in responders and nonresponders, and nonsuppression may occur despite clinical improvement (Schüle, 2007). Therefore, the importance of HPA axis dysregulation for the short-term efficacy of antidepressants continues to be a matter of debate. The aim of our study was to explore whether there are changes of in vivo SERT availability measured with [C]DASB and differences in HPA axis activity in healthy volunteers.