Persistent infection or chronic inflammation contributes significantly to tumourigenesis and tumour progression. C-X-C motif ligand 8 (CXCL8) is a chemokine that acts as an important multifunctional cytokine to modulate tumour proliferation, invasion and migration in an autocrine or paracrine manner. Studies have suggested that CXCL8 and its cognate receptors, C-X-C chemokine receptor 1 (CXCR1) and CX-C chemokine receptor 2 (CXCR2), mediate the initiation and development of various cancers including breast cancer, prostate cancer, lung cancer, colorectal carcinoma and melanoma. CXCL8 also integrates with multiple intracellular signalling pathways to produce coordinated effects. Neovascularisation, which provides a basis for fostering tumour growth and metastasis, is now recognised as a critical function of CXCL8 in the tumour microenvironment. In this review, we summarize the biological functions and ficlinical significance of the CXCL8 signalling axis in cancer. We also propose that CXCL8 may be a potential therapeutic target for cancer treatment

CD44, a multi-structural and multifunctional transmembrane glycoprotein, was initially identified as a receptor for hyaluronan that participates in both physiological and pathological processes. CD44 is found to be closely linked to the development of various solid tumors. Molecular studies have revealed that high CD44 expression was correlated with the phenotypes of cancer stem cells and epithelial–mesenchymal transition, thereby contributing to tumor invasion, metastasis, recurrence, and chemoresistance. Correspondingly, blockade of CD44 has been demonstrated to be capable of attenuating the malignant phenotype, slowing cancer progression, and reversing therapy resistance. Clinical analyses showed that high CD44 expression is associated with poor survival of various cancer patients, indicating that CD44 can be a potential prognostic marker. In this review, we summarize recent research progress of CD44 on tumor biology and the clinical significance of CD44.

Cluster of differentiation 44 (CD44), a well-known transmembrane glycoprotein, serves as a promoting factor in the carcinogenesis and progression of a variety of neoplasms. Previous studies have demonstrated that aberrant expression of CD44 was associated with the initiation, invasion, metastasis, and therapy-resistance of breast cancer, but whether there was any association between CD44 and pathological characteristics of breast cancer or epidermal growth factor receptor (EGFR) has not been clearly elucidated. In this study, we utilized public microarray data analysis and tissue microarray technologies to display that CD44 level was enhanced in breast cancer and was significantly correlated with histological grade and the status of estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 (HER2) and EGFR. Furthermore, mRNA expression of CD44 in breast tumors was positively correlated with basal cytokeratin markers KRT5 and KRT17, but inversely associated with luminal marker FOXA1. Besides, Kaplan-Meier analysis showed that high CD44 mRNA level had adverse impact on the progression-free survival of patients with HER2-expressing or basal-like breast cancer. Functionally, inhibition of EGFR activity by erlotinib impaired the invasion and migration ability of breast cancer cell lines. Western blot assays demonstrated that erlotinib treatment decreased the expression of CD44, accompanied with the reduced protein levels of mesenchymal and cancer stem cell markers. Collectively, this study suggested that the expression of CD44 was upregulated by EGFR pathway and CD44 had a robust impact on the development of breast cancer.