• Korean Journal of Head & Neck Oncology
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• v.20 no.2
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• pp.147-155
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• 2004

Objectives: Head and neck squamous cell carcinoma (HNSCC) is the most common head and neck malignant tumor. The molecular genetic changes involving both oncogenes and tumor suppressor genes are known to be involved in head and neck squamous cell carcinogenesis, but the roles of the known tumor suppressor genes in carcinogenesis are not fully elucidated. The objectives of this study are to demonstrate the genetic alterations including the loss of heterozygosity (LOH) , amplification, and microsatellite instability of known tumor suppressor genes in HNSCC and to evaluate the relationship between genetic alterations of tumor suppressor genes and clinicopathologic features. Materials and Methods: Genetic alterations of 10 micro satellite markers of the 6 known tumor suppressor genes (APC, EXT1, DPC4, p16, FHIT, and PTEN) were analysed by DNA-PCR in paraffin-embedded histologically confirmed HNSCC specimens. Results: The genetic alterations of tumor suppressor genes were found frequently. Among the genetic alterations, LOH was most frequently found one. LOH was found frequently in APC (45.4%), EXT1 (36.4%), DPC4 (54.5%), and p16 (50%), but not found in FHIT. Also, the author found that abnormalities of APC gene was related to cervical lymph node metastasis and recurrence and that abnormalities of EXT1 gene were coexisted with those of APC gene or DPC4 gene. But these coexistences had no correlation with clinical features. Conclusion: These results suggested that APC, EXT1, p16, and DPC4 genes might play important roles and multiple tumor suppressor genes may participate dependently or independently in the carcinogenesis of HNSCC. These results also suggested that APC gene might relate to prognosis.

• BMB Reports
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• v.48 no.8
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• pp.454-460
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• 2015

Naturally occurring reoviruses are live replication-proficient viruses that specifically infect human cancer cells while sparing their normal counterpart. Since the discovery of reoviruses in 1950s, they have shown various degrees of safety and efficacy in pre-clinical or clinical applications for human anti-cancer therapeutics. I have recently discovered that cellular tumor suppressor genes are also important in determining reoviral tropism. Carcinogenesis is a multi-step process involving the accumulation of both oncogene and tumor suppressor gene abnormalities. Reoviruses can exploit abnormal cellular tumor suppressor signaling for their oncolytic specificity and efficacy. Many tumor suppressor genes such as p53, ataxia telangiectasia mutated (ATM), and retinoblastoma associated (RB) are known to play important roles in genomic fidelity/maintenance. Thus, a tumor suppressor gene abnormality could affect host genomic integrity and likely disrupt intact antiviral networks due to the accumulation of genetic defects which in turn could result in oncolytic reovirus susceptibility. This review outlines the discovery of oncolytic reovirus strains, recent progresses in elucidating the molecular connection between oncogene/tumor suppressor gene abnormalities and reoviral oncotropism, and their clinical implications. Future directions in the utility of reovirus virotherapy is also proposed in this review. [BMB Reports 2015; 48(8): 454-460]

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9059-9064
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• 2014

MicroRNAs (miRNAs) are ubiquitously expressed small, non-coding RNAs that negatively regulate gene expression at a post transcriptional/translational level. They have emerging as playing crucial roles in cancer at all stages ranging from initiation to metastasis. As a tumor suppressor miRNA, aberrant expression of microRNA-29b (miR-29b) has been detected in various types of cancer, and its disturbance is related with tumor development and progression. In this review, we summarize the latest findings with regard to the tumor suppressor signatureof miR-29b and its regulatory mechanisms. Our review highlights the diverse relationships between miR-29b and its target genes in malignant tumors.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3539-3548
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• 2012

The Nm23 gene is a metastatic suppressor identified in a melanoma cell line and expressed in different tumors where their levels of expression are associated with reduced or increased metastatic potential. Nm23 is one of the over 20 metastasis suppressor genes (MSGs) confirmed in vivo. It is highly conserved from yeast to human, implying a critical developmental function. Tumors with alteration of the p53 gene and reduced expression of the Nm23 gene are more prone to metastasis. Nm23-H1 has 3'-5' exonuclease activity. This review focuses on the role of Nm23 in cancer progression and also a potential novel target for cancer therapy.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.19
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• pp.8469-8474
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• 2014

Introduction: Recent studies have indicated that down-regulation of the suppressor of cytokine signaling-1 (SOCS-1) gene results in tumor formation and that SOCS-1 acts as a tumor suppressor gene. SOCS-1 has been also suggested to function as a tumor suppressor with colorectal cancer. Objectives: In the present study, we aimed to determine the association of SOCS-1 expression in colorectal cancer tissues with clinicopathologic characteristics immunohistochemically and also to identify its prognostic significance. Materials and Methods: SOCS-1 expression was studied immunohistochemically in 67 patients diagnosed with resected colorectal carcinomas and 30 control subjects. Results: SOCS-1 expression was found in 46.3% of tumor tissues and 46.7% of the control group. Statistical analyses did not establish any significant association between SOCS-1 expression and clinicopathologic characteristics. Also, no significant association with SOCS-1 expression was found using progression-free survival and overall survival analyses (p=0.326 and p=0.360, respectively). Conclusions: Our results show that SOCS-1 has no prognostic significance in colorectal cancer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.984-991
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• 1997

New tumor suppressor gene, snm23, homologous to human nm23/NDP kinase (human nucleoside diphosphate kinase) gene whose product has a tumor metastasis inhibitory activity, was first cloned from Korean tiger shark (Scyliorhinus forazame) skin cDNA library constructed by using a $\lambda$ ZAP-II cDNA synthesis kit. About $1\times10^5$ plaques were screened and several positive plaques were isolated and confirmed by second screening. The phagemid containing a positive clone from the Uni-Zap XR vector was excised in vivo and the gene containing the tumor metastasis suppressor protein was named as snm23. Cloned gene, snm23, was sequenced with ABI-PRISM 310 Genetic Analyzer. The nucleotide and deduced amino acid sequences of snm23 have shown an open reading frame consisting of 450 base pairs that correspond to a protein of 150 amino acid residues, with a calculated molecular mass of 16.8 kDa. Sequence comparison of snm23 with human nm23/NDP kinase was performed by using Blast protein data base of National Center for Biotechnology Information. In order to determine tissue specificity, reverse transcription-polymerase chain reaction (RT-PCR) was used. Good expression level of snm23/NDP kinase was detected at the tissues from skin, cartilage, and liver of Korean tiger shark.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.4
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• pp.1599-1603
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• 2015

Background: Epigenetic silencing of tumor suppressor genes due to promoter hypermethylation is one of the frequent mechanisms observed in cancers. Hypermethylation of several tumor suppressor genes involved in cell cycle regulation has been reported in many types of tumors including oral squamous cell carcinomas. LATS1 (Large Tumor Suppressor, isoform 1) is a novel tumor suppressor gene that regulates cell cycle progression by forming complexes with the cyclin dependent kinase, CDK1. Promoter hypermethylation of the LATS1 gene has been observed in several carcinomas and also has been linked with prognosis. However, the methylation status of LATS1 in oral squamous cell carcinomas is not known. As oral cancer is one of the most prevalent forms of cancer in India, the present study was designed to investigate the methylation status of LATS1 promoter and associate it with histopathological findings in order to determine any associations of the genetic status with stage of differentiation. Materials and Methods: Tumor chromosomal DNA isolated from biopsy tissues of thirteen oral squamous cell carcinoma biopsy tissues were subjected to digestion with methylation sensitive HpaII enzyme followed by amplification with primers flanking CCGG motifs in promoter region of LATS1 gene. The PCR amplicons were subsequently subjected to agarose gel electrophoresis along with undigested amplification control. Results: HpaII enzyme based methylation sensitive PCR identified LATS1 promoter hypermethylation in seven out of thirteen oral squamous cell carcinoma samples. Conclusions: The identification of LATS1 promoter hypermethylation in seven oral squamous cell carcinoma samples (54%), which included one sample with epithelial dysplasia, two early invasive and one moderately differentiated lesions indicates that the hypermethylation of this gene may be one of the early event during carcinogenesis. To the best of our knowledge, this is the first study to have explored and identified positive association between LATS1 promoter hypermethylation with histopathological features in oral squamous cell carcinomas.

• Journal of Gastric Cancer
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• v.3 no.4
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• pp.214-220
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• 2003

Purpose: The aim of this study was to investigate the frequency of loss of heterozygosity and the microsatellite instability at multiple tumor suppressor gene loci in gastric adenocarcinomas. Materials and Methods: Loss of heterozygosity and the microsatellite instability at several tumor suppressor gene loci were analyzed in 29 primary gastric carcinomas by using microdissection and the polymerase chain reaction. Results: Twenty-three ($79\%$) of the 29 cases demonstrated loss of heterozygosity at one or more loci. The frequency of loss of heterozygosity at the p53 locus was the highest ($63\%$) and those at the VHL, APC, p16, Rb, MEN1, BRCA1, DPC4, 3p21, and 16p13 region were $41\%,\;36\%,\;19\%,\;29\%,\;33\%,\;26\%,\;21\%,\;32\%,\;and\;11\%$, respectively. Compared with histological type, loss of heterozygosity was more common in diffuse-type gastric cancer (P<0.01). Interestingly, 9 of 10 tumors with allelic deletion at the p53 locus showed loss of heterozygosity at other tumor suppressor gene loci. The microsatellite instability was also detected in 6 ($20\%$) of the 29 cases at one or more loci. Conclusion: These data suggest that frequent loss of heterozygosity and the microsatellite instability at multiple tumor suppressor genes might be required for the development and the progression of gastric carcinomas and that p53 allelic loss may be the most frequent event in the development of gastric carcinomas.

• BMB Reports
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• v.39 no.6
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• pp.649-655
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• 2006

The NSAID activated gene (NAG-1), a member of the TGF-$\beta$ superfamily, is involved in tumor progression and development. The over-expression of NAG-1 in cancer cells results in growth arrest and increase in apoptosis, suggesting that NAG-1 has anti-tumorigenic activity. This conclusion is further supported by results of experiments with transgenic mice that ubiquitously express human NAG-1. These transgenic mice are resistant to the development of intestinal tumors following treatment with azoxymethane or by introduction of a mutant APC gene. In contrast, other data suggest a pro-tumorigenic role for NAG-1, for example, high expression of NAG-1 is frequently observed in tumors. NAG-1 may be like other members of the TGF-$\beta$ superfamily, acting as a tumor suppressor in the early stages, but acting pro-tumorigenic at the later stages of tumor progression. The expression of NAG-1 can be increased by treatment with drugs and chemicals documented to prevent tumor formation and development. Most notable is the increase in NAG-1 expression by the inhibitors of cyclooxygenases that prevent human colorectal cancer development. The regulation of NAG-1 is complex, but these agents act through either p53 or EGR-1 related pathways. In addition, an increase in NAG-1 is observed in inhibition of the AKT/GSK-$3{\beta}$ pathway, suggesting NAG-1 alters cell survival. Thus, NAG-1 expression is regulated by tumor suppressor pathways and appears to modulate tumor progression.

• Genomics & Informatics
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• v.20 no.1
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• pp.6.1-6.15
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• 2022

Litorilituus sediminis is a Gram-negative, aerobic, novel bacterium under the family of Colwelliaceae, has a stunning hypothetical protein containing domain called von Hippel-Lindau that has significant tumor suppressor activity. Therefore, this study was designed to elucidate the structure and function of the biologically important hypothetical protein EMK97_00595 (QBG34344.1) using several bioinformatics tools. The functional annotation exposed that the hypothetical protein is an extracellular secretory soluble signal peptide and contains the von Hippel-Lindau (VHL; VHL beta) domain that has a significant role in tumor suppression. This domain is conserved throughout evolution, as its homologs are available in various types of the organism like mammals, insects, and nematode. The gene product of VHL has a critical regulatory activity in the ubiquitous oxygen-sensing pathway. This domain has a significant role in inhibiting cell proliferation, angiogenesis progression, kidney cancer, breast cancer, and colon cancer. At last, the current study depicts that the annotated hypothetical protein is linked with tumor suppressor activity which might be of great interest to future research in the higher organism.