Classification of biomarker
Major cellular biomarkers correlated with the clinical outcome of cancer have been reported, which were refined with a focus on the relationship between prognostic or survival parameters of cancer patients and their expression levels, mainly using immunohistochemistry (Oliveira & Ribeiro-Silva, 2011).
The biomarkers could be classified into five groups based on their biological functions:
- cell cycle progression and proliferation;
- tumor suppression and apoptosis;
- cell adhesion and matrix degradation.
Interleukin-6 (IL-6) is a pleiotropic cytokine with significant functions in the regulation of the immune system. As a potent pro-inflammatory cytokine, IL-6 plays a pivotal role in host defense against pathogens and acute stress. However, increased or deregulated expression of IL-6 significantly contributes to the pathogenesis of various human diseases. Numerous preclinical and clinical studies have revealed the pathological roles of the IL-6 pathway in inflammation, autoimmunity, and cancer. Based on the rich body of studies on biological activities of IL-6 and its pathological roles, therapeutic strategies targeting the IL-6 pathway are in development for cancers, inflammatory and autoimmune diseases.
Overexpression of IL-6 was associated with tumor progression through inhibition of cancer cell apoptosis, stimulation of angiogenesis, and drug resistance. Clinical studies have revealed that increased serum IL-6 concentrations in patients are associated with advanced tumor stages of various cancers (e.g., multiple myeloma, non-small cell lung carcinoma, colorectal cancer, renal cell carcinoma, prostate cancer, breast cancer and ovarian cancer) and short survival in patients. Therefore, blocking IL-6 signaling is a potential therapeutic strategy for cancer (i.e., anti-IL-6 therapy) characterized by pathological IL-6 overproduction. Normal level of IL-6 is (5-15 pg/ml), but the concentration of IL-6 is elevated in some pathological condition about (IL-6 (5-15 pg/ml).
IL-8, a cytokine initially discovered by Yoshimura, involves in inflammation and immunity, and shows tumorigenic and pro-angiogenic properties. Interleukin 8 (IL-8), is a PR inflammatory chemokine functioned in neutrophil chemotaxis and activation. Increased expression of IL-8 and its receptors has been reported in various cancer cells. In a previous study based on primary breast cancer tissues, a high expression of IL-8 was correlated with the angiogenesis process that was essential for tumor growth and progression. Besides, IL-8 was correlated with the increased proliferation of cancer cells. The role of IL-8 in cancer progression was reported to be associated with lymph node positive status, higher TNM staging, as well as the hormone receptors.
In this study, IL-8 expression was significantly elevated compared with that of the normal control. Patients with response to treatment showed decreased IL-8 compared with the baseline levels. On this basis, we propose that IL-8 may serve as an important prognostic marker for breast cancer, and may contribute to the identification of genes and proteins differentially expressed in the breast cancer patients. And it plays an important role in the process of glioma stem-like cell vascularization in the latest research.