Overexpression of the DNA sensor proteins, absent in melanoma 2 and interferon‐inducible 16, contributes to tumorigenesis of oral squamous cell carcinoma with p53 inactivation

Abstract

The development of oral squamous cell carcinoma (OSCC) is a multistep process that requires the accumulation of genetic alterations. To identify genes responsible for OSCC development, we performed high-density single nucleotide polymorphism array analysis and genome-wide gene expression profiling on OSCC tumors. These analyses indicated that the absent in melanoma 2 (AIM2) gene and the interferon-inducible gene 16 (IFI16) mapped to the hematopoietic interferon-inducible nuclear proteins. The 200-amino-acid repeat gene cluster in the amplified region of chromosome 1q23 is overexpressed in OSCC. Both AIM2 and IFI16 are cytoplasmic double-stranded DNA sensors for innate immunity and act as tumor suppressors in several human cancers. Knockdown of AIM2 or IFI16 in OSCC cells results in the suppression of cell growth and apoptosis, accompanied by the downregulation of nuclear factor kappa-light-chain-enhancer of activated B cells activation. Because all OSCC cell lines have reduced p53 activity, wild-type p53 was introduced in p53-deficient OSCC cells. The expression of wild-type p53 suppressed cell growth and induced apoptosis via suppression of nuclear factor kappa-light-chain-enhancer of activated B cells activity. Finally, the co-expression of AIM2 and IFI16 significantly enhanced cell growth in p53-deficient cells; in contrast, the expression of AIM2 and/or IFI16 in cells bearing wild-type p53 suppressed cell growth. Moreover, AIM2 and IFI16 synergistically enhanced nuclear factor kappa-light-chain-enhancer of activated B cells signaling in p53-deficient cells. Thus, expression of AIM2 and IFI16 may have oncogenic activities in the OSCC cells that have inactivated the p53 system. (Cancer Sci 2012; 103: 782-790) O ral squamous cell carcinoma is commonly found in lowincome communities. This cancer mainly affects older men; 90% of cases are in men over 45 years old who have been exposed to risk factors including tobacco and/or alcohol (International Agency for Research on Cancer [IARC] 2004). OSCC is the sixth most common cancer worldwide and affects approximately 270 000 people each year.(1) The incidence and rate of mortality from OSCC are rising in several regions of Europe, Australia and Asia, including Japan. Despite recent progress in OSCC diagnosis and therapy, the 5-year survival rate has not improved in more than two decades. Oral carcinogenesis is a multifactorial cascade involving numerous genetic changes that affect the activity of oncogenes, tumor suppressor genes and other classes of diseaserelated genes. Chronic exposure to carcinogens, such as tobacco, causes genetic changes in the epithelial cells of the oral mucosa. The activation of the COX-2,epidermal growth factor receptor, (4) and cyclin D1 oncogenes and the inactivation of the p16 and p53 tumor suppressor genes have also been reported in OSCC.(5-7) In addition to tobacco smoke exposure, chronic alcohol use and chronic inflammation can both induce genetic alterations.(3) The causative agent of cervical cancer, HPV is also reportedly associa...

Absent in melanoma 2 proteins in the development of cancer

“…Furthermore, the restoration of AIM2 expression in p53-deficient OSCC cells increased cell proliferation and activated NF-jB activity. In contrast, the Absent in melanoma 2 proteins in the development of cancer restoration of AIM2 expression in OSCC cells that expressed the functional p53 inhibited cell growth [32]. Importantly, these observations raised an interesting possibility that AIM2-mediated inhibition of cell growth in OSCC cells and possibly other cell types depends on the p53 functions.…”

“…The development of oral squamous cell carcinoma (OSCC) is associated with the amplification of the 1q23 region, and genes within this region, such as AIM2, are overexpressed [32]. Intriguingly, knockdown of AIM2 expression in OSCC cell lines resulted in decreased activation of NF-jB and suppression of cell growth and apoptosis [32].…”

“…Intriguingly, knockdown of AIM2 expression in OSCC cell lines resulted in decreased activation of NF-jB and suppression of cell growth and apoptosis [32]. Furthermore, the restoration of AIM2 expression in p53-deficient OSCC cells increased cell proliferation and activated NF-jB activity.…”

Nutlin-3-induced redistribution of chromatin-bound IFI16 in human hepatocellular carcinoma cells in vitro is associated with p53 activation

“…Loss of IFI16 results in deregulation of p53-mediated apoptosis in breast cancer [8] . Consistently, overexpressed IFI16 has no effect on cell growth in p53-inactived oral squamous cell carcinoma [49] . Our previous hypothesis also proposed that IFI16 mis-localization may be a contributing factor to HCC progression [21] .…”

The Duality of AIM2 Inflammasome: A Focus on its Role in Autoimmunity and Skin Diseases

“…In support of the role of AIM2 inflammasome as a suppressor of cancer, it has been found that colorectal cancer patients, whose tissues showed a reduced AIM2 expression have a poorer prognosis compared to those with an up-regulation of AIM2 (Dihlmann et al, 2014). Moreover, AIM2 downregulation has also been reported in prostate cancer (Ponomareva et al, 2013), whereas increased expression has been detected in nasopharyngeal carcinoma Chen et al, 2012), oral squamous cell carcinoma (Kondo et al, 2012) and lung adenocarcinoma (Kong et al, 2015), suggesting that the differential expression of AIM2 in a range of tumor tissues could relate to its possible unique role in different types of cancer (Man et al, 2016). The mechanism by which AIM2 regulates tumorigenesis has been demonstrated by Wilson et al (2015) and described in a mouse model of colitis-associated colorectal cancer (Man et al, 2015b).…”