Table 2.

Expression and role of galectin-9 in different types of cancer.

Type of cancer	Expression of Gal-9	Activity	Possible mechanism	Prognosis	Refs.
Gastric cancer	Down-regulated	Tumor suppressor	Inducing tumor cell apoptosis	Favorable	71,72
Colorectal cancer	Down-regulated	Tumor suppressor	Inducing tumor cell apoptosis and inhibiting proliferation, reducing tumor escape immune surveillance, and inducing autophagy	Favorable	64,75, 76, 77
Lung cancer	Down-regulated	Tumor suppressor	Suppressing tumor cell adhesion and invasion, and activating NK cells	Favorable	78,80,81
Hepatocellular carcinoma	Down-regulated	Tumor suppressor	Inducing tumor cell apoptosis, and inhibiting the anti-tumor immune response by inducing T cell senescence in Kupffer cells and other APCs	Favorable	66,83,84
Esophageal carcinoma	Down-regulated	Tumor suppressor	Inducing tumor cell apoptosis	Favorable	68,85,86
Melanoma	Down-regulated	Tumor suppressor	Inducing tumor cell apoptosis	Favorable	11,94,95
Breast cancer	Up-regulated	Tumor promotor	Inhibiting immune surveillance through the Tim-3-Gal-9 pathway, and inducing tumor cell aggregation to reduce metastasis	Favorable	13,54,69
Glioma	Up-regulated	Tumor promotor	Tumor immunosuppression or immune escape through the Tim-3-Gal-9 pathway	Unfavorable	61,88
Pancreatic carcinoma	Up-regulated	Tumor promotor	Reprogramming macrophages and exerting immunosuppressive effects	Unfavorable	42,60,91
Cervical carcinoma	Up-regulated	Tumor promotor	Tumor immune escape through activation of the Tim-3-Gal-9 pathway	Unfavorable	59,93
Lymphoma	Up-regulated	Tumor promotor	Reducing CD8+ T cell infiltration	Unfavorable	62
Leukemia	Up-regulated	Tumor promotor	Immune escape through the Tim-3-Gal-9 pathway	Unfavorable	51,52,101