Abstract
Inhibitor of growth family 5 (ING5) functions as a type-II tumor suppressor gene and exerts an important role in DNA repair, apoptotic induction, proliferative inhibition, chromatin remodeling and the invasion process. In the present study, immunohistochemistry was performed to characterize the expression profile of ING5 protein on a tissue microarray containing mouse and human normal tissues, and human cancer tissues, including hepatocellular (n=62), renal clear cell (n=62), pancreatic (n=62), esophageal squamous cell (n=45), cervical squamous cell (n=31), breast (n=144), gastric (n=196), colorectal (n=96), endometrial (n=96) and lung carcinoma (n=192). In the mouse tissues, ING5 expression was detected in the cytoplasm of neurons, the nephric tubule and glomerulus, alveolar epithelium, gastrointestinal glands, squamous epithelium of the skin and skeletal muscles. By contrast, ING5 was localized to the cell nucleus in breast tissues. In human tissues, ING5 protein was primarily localized in the cytoplasm. However, ING5 was detected in the cytoplasm and nucleus in various types of normal tissues, including the tongue, stomach, intestine, lung and breast. In total, ING5 expression was detected in 400/986 cancer tissues (40.6%). In the majority of cases, ING5 expression was observed to be restricted to the cytoplasm. However, ING5 was also detected in the nucleus in a number of cancer tissues, including gastric, colorectal and lung carcinoma. Notably, ING5 was more frequently expressed in breast (79.9%), colorectal (56.3%) and endometrial carcinoma (50.0%). The incidence of ING5 expression in hepatocellular carcinoma (14.5%) and pancreatic carcinoma (22.6%) was low. These findings indicate that ING5 may be involved in cell regeneration and be associated with colorectal carcinogenesis.
Highlights
Inhibitor of growth family 5 (ING5) is a member of the ING protein family and functions as a type‐II tumor suppressor gene
Reduced ING5 expression was detected in pancreatic carcinoma cells transfected with a microRNA‐196a precursor, accompanied by decreased apoptosis, increased invasion and proliferation compared with control cells [8]
ING5 reactivity was detectable in the cytoplasm of neurons, the nephric tubule and glomerulus, alveolar epithelium, glands of the stomach and intestine, squamous epithelium of the skin and skeletal was detected in the tongue, stomach and skin, whereas weak immunoreactivity was observed in the cerebellum, brain stem, thymus and skeletal muscle (Table II)
Summary
Inhibitor of growth family 5 (ING5) is a member of the ING protein family and functions as a type‐II tumor suppressor gene. The loss of heterozygosity on the long arm of chromosome 2, where the ING5 gene is YANG et al: EXPRESSION OF ING5 IN NORMAL AND CANCER TISSUES located, was detected in 85% (33/39) of oral carcinoma cases. Reduced ING5 mRNA expression in 61% of oral squamous cell carcinoma cases with missense mutations located within the LZL finger and NCR domains of the ING5 protein has been reported [12]. In head and neck squamous cell carcinoma (HNSCC), nuclear ING5 may modulate the transactivation of target genes, and promote apoptosis and cell cycle arrest by interacting with p300 and p21 [13,14]. The expression profiling of ING5 protein has been investigated in normal mouse and human tissues, as well as in human cancer tissues
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