Reduced expression of the Syk gene is correlated with poor prognosis in human breast cancer

• Published in: Cancer letters Vol. 189; no. 1; pp. 97 - 102
• Main Authors: Toyama, Tatsuya, Iwase, Hirotaka, Yamashita, Hiroko, Hara, Yasuo, Omoto, Yoko, Sugiura, Hiroshi, Zhang, Zhenhuan, Fujii, Yoshitaka
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 10.01.2003; Elsevier; Elsevier Limited
• Subjects: Animal tumors. Experimental tumors; Biological and medical sciences; Breast cancer; Breast Neoplasms - genetics; Carcinogenesis, carcinogens and anticarcinogens; Enzyme Precursors - genetics; Experimental genital and mammary tumors; Gene expression; General aspects; Humans; Intracellular Signaling Peptides and Proteins; Kinases; Medical sciences; Metastasis; Neoplasm Metastasis; Polyclonal antibodies; Prognosis; Protein-Tyrosine Kinases - genetics; Proteins; Rodents; Syk; Syk Kinase; Tumor suppressor gene; Tumors; Japan; Breast cancer; Metastasis; Syk; Tumor suppressor gene; Human; Prognosis; Enzyme; Transferases; Genotype; Malignant tumor; Gene expression; In vitro; Polymerase chain reaction; Mammary gland diseases; Gene; Risk factor; Genetics; Mammary gland; Protein-tyrosine kinase
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/S0304-3835(02)00463-9

Syk is a non-receptor type of protein-tyrosine kinase that is widely expressed in hematopoietic cells. Syk expression has been reported in breast tissue. However, the function of Syk in breast tissue remains unclear. In 25 (28%) of the 90 paired samples of human breast cancer and the matched, adjacent non-cancerous tissues examined here, reduced mRNA expression of Syk in the breast cancer tissues was observed by real-time quantitative reverse transcription–polymerase chain reaction. Eight (32%) of the 25 cases showing reduced Syk mRNA expression demonstrated distant metastasis of breast cancer, while only 4 (6%) of the 65 cases who did not show reduced Syk expression had distant metastasis. Kaplan–Meier curves demonstrated that patients with reduced Syk expression were at significantly increased risk for distant metastasis ( P=0.0003 ). Our data suggest that reduced Syk expression in breast cancers is associated with distant metastasis and poor prognosis; therefore, Syk is considered to be a potential tumor suppressor and anti-metastasis gene in human breast cancer.