Immunohistochemical study of tumor necrosis factor α expression in autopsy and surgical specimens of human lumbar intervertebral discs. To investigate the occurrence and localization of tumor necrosis factor α in intervertebral disc tissue and to correlate its expression with age and the degree of disc degeneration. The source and origin of discogenic pain are as yet unknown. Recently identified changes of the cellular phenotype during senescence and disc pathology with partly phagocytic properties suggest an ‘inflammatory’ phenotype. Tumor necrosis factor α is one of the most potent proinflammatory cytokines possibly modulating cellular phenotypes. It may also promote pain induction. Very little is known about the occurrence and localization of tumor necrosis factor α in intervertebral disc tissue of defined age and degree of histologic tissue degeneration. The study population comprised 20 cross-sections of the complete motion segment of human lumbar vertebrae (age range 0–86 years) obtained at autopsy and 28 surgical disc specimens of individuals undergoing lumbar surgical interventions for various reasons. The temporospatial distribution of tumor necrosis factor α-positive cells using a polyclonal antibody was correlated with a histologic degeneration score. Tumor necrosis factor α is expressed substantially in (nonsymptomatic) autopsy material in fetal/infantile and older adult nucleus pulposus, whereas it is sparsely expressed in adolescent and young adult nucleus pulposus. In the anulus fibrosus, tumor necrosis factor α is not found in young adults (<25 years), but then significantly increases in extent. In contrast, symptomatic nucleus pulposus and anulus fibrosus (surgical material) contain substantially more tumor necrosis factor α-positive cells. A significant positive correlation of tumor necrosis factor α expression and disc degeneration (histologic degeneration score) was found for the anulus fibrosus in both sample groups. In the surgical material, an additional significant positive correlation was identified for nuclear tumor necrosis factor α, disc degeneration, and age. Tumor necrosis factor α is substantially expressed in disc material of symptomatic patients (surgical specimens) in comparison to samples taken at autopsy. The expression of tumor necrosis factor α in early fetal/infantile nucleus pulposus may indicate ‘physiologic’ tissue disarrangement with closure of the blood vessel canals. The expression of tumor necrosis factor α in adult discs, in contrast, is statistically associated with disc degeneration. Its occurrence in adults of more advanced age suggests that tumor necrosis factor α is not involved in the initiation of disc degeneration, but may be associated with further promotion of degenerative disarrangement and pain induction.

The dietary antioxidant Curcumin has been proposed for cancer chemoprevention since it induces apoptosis and inhibits the formation of breast cancer metastases. Curcumin acts through the inhibition of phosphorylation of the inhibitor of kappa B (IκB), which in turn reduces the nuclear translocation of nuclear factor kappa B (NFκB), an inflammation- and cell survival-related transcription factor. However, it is not clear whether the strong antimetastatic effect can exclusively be explained by inhibition of NFκB. Here, we addressed the effects of Curcumin (IC ₅₀ = 17 μM) in MDA-MB-231 breast cancer cells using microarray gene expression analyses. Among the 62 genes whose expression was significantly altered, we found the two inflammatory cytokines CXCL1 and -2 (Groα and -β) that were downregulated. Further validation of the microarray results by quantitative real-time reverse transcription–polymerase chain reaction, western blots and enzyme-linked immunosorbent assay revealed that Curcumin impairs transcription of CXCL1 and -2 >24 h and reduces the corresponding proteins. Using small interfering RNA techniques, we elucidated the underlying molecular mechanism revealing that reduction of CXCL1 and -2 messenger RNA levels is NFκB dependent and requires intact IκBα expression. Moreover, CXCL1 and -2 silencing leads to downregulation of several metastasis-promoting genes among which we found the cytokine receptor CXCR4. We therefore suggest that the decrease of CXCL1 and -2 mediated by Curcumin is involved in the inhibition of metastasis.

In America and Western Europe, prostate cancer is the second leading cause of death in men. Emerging evidence suggests that chronic inflammation is a major risk factor for the development and metastatic progression of prostate cancer. We previously reported that the chemopreventive polyphenol curcumin inhibits the expression of the proinflammatory cytokines CXCL1 and -2 leading to diminished formation of breast cancer metastases. In this study, we analyze the effects of curcumin on prostate carcinoma growth, apoptosis and metastasis. We show that curcumin inhibits translocation of NFκB to the nucleus through the inhibition of the IκB-kinase (IKKβ, leading to stabilization of the inhibitor of NFκB, IκBα, in PC-3 prostate carcinoma cells. Inhibition of NFκB activity reduces expression of CXCL1 and -2 and abolishes the autocrine/paracrine loop that links the two chemokines to NFκB. The combination of curcumin with the synthetic IKKβ inhibitor, SC-541, shows no additive or synergistic effects indicating that the two compounds share the target. Treatment of the cells with curcumin and siRNA-based knockdown of CXCL1 and -2 induce apoptosis, inhibit proliferation and downregulate several important metastasis-promoting factors like COX2, SPARC and EFEMP. In an orthotopic mouse model of hematogenous metastasis, treatment with curcumin inhibits statistically significantly formation of lung metastases. In conclusion, chronic inflammation can induce a metastasis prone phenotype in prostate cancer cells by maintaining a positive proinflammatory and prometastatic feedback loop between NFκB and CXCL1/-2. Curcumin disrupts this feedback loop by the inhibition of NFκB signaling leading to reduced metastasis formation in vivo.

Dissemination of metastatic cells probably occurs long before diagnosis of the primary tumor. Metastasis during early phases of carcinogenesis in high risk patients is therefore a potential prevention target. The plant polyphenol Curcumin has been proposed for dietary prevention of cancer. We therefore examined its effects on the human breast cancer cell line MDA-MB-231 in vitroand in a mouse metastasis model. Curcumin strongly induces apoptosis in MDA-MB-231 cells in correlation with reduced activation of the survival pathway NFĸB, as a consequence of diminished ΙĸB and p65 phosphorylation. Curcumin also reduces the expression of major matrix metalloproteinases (MMPs) due to reduced NFĸ B activity and transcriptional downregulation of AP-1. NFĸ B/p65 silencing is sufficient to downregulate c-jun and MMP expression. Reduced NFĸ B/AP-1 activity and MMP expression lead to diminished invasion through a reconstituted basement membrane and to a significantly lower number of lung metastases in immunodeficient mice after intercardiac injection of 231 cells (p=0.0035). 68% of Curcumin treated but only 17% of untreated animals showed no or very few lung metastases, most likely as a consequence of down-regulation of NFĸ B/AP-1 dependent MMP expression and direct apoptotic effects on circulating tumor cells but not on established metastases. Dietary chemoprevention of metastases appears therefore feasible.