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.

Therefore, circulating IL-6 might be prognostic indicator in colorectal cancer.

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 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.

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