Novel partners of S100A8 identified in laryngeal cancer cell lines.

OBJECTIVE: To explore mechanism of S100A8 in the oncogenesis and development of laryngeal cancer. METHODS: Proteins interacting with S100A8 were isolated from laryngeal cancer cell lines Hep-2 by immunoprecipitation assay with anti-S100A8 antibody. The target bands were cut out and identified by maxtrix assisted laser desorption/ionization time of flight (MALDI-TOF). The peptide mass fingerprinting data of the proteins identified were analyzed based on the Mascot database. The NF-kappa B binding sites of the proteins were predicted by P-Match software. The binding ability of one of the proteins to S100A8 was confirmed by co-immunoprecipitation and immunocytochemistry methods. RESULTS: Four proteins interacting with S100A8 were obtained, which were hypothetical protein LOC80154, MHC class I HLA-B, similar to T-box 1 isoform C and sarcolemmal associated protein 1. The four genes were predicted to have NF-kappa B binding sites. MHC class I HLA-B, which is one of targets in NF-kappa B pathway, was first confirmed to have the binding ability to S100A8. CONCLUSION: The novel partners of S100A8 identified in the study might be involved in NF-kappa B pathway. The binding ability of MHC class I HLA-B to S100A8 implies that S100A8 might function as a new member with other proteins including HLA-B in NF-kappa B pathway. These findings provide a new clue to further study on the molecular mechanism of S100A8 in the genesis of laryngeal carcinomas.

Study of the SH3-domain GRB2-like 2 gene expression in laryngeal carcinoma.

BACKGROUND: Laryngeal carcinoma is a common malignant tumor of the upper respiratory tract, and in 95% of cases the tumor is laryngeal squamous cell carcinoma (LSCC). The abnormity of SH3-domain GRB2-like 2 (SH3GL2) gene was found in LSCC. In order to clarify the relationship between SH3GL2 gene and LSCC, we evaluated the expression of the SH3GL2 gene in LSCC. METHOD: Real-time PCR, immunohistochemistry and Western blotting were used to detect the mRNA and protein expression and find the various rules of SH3GL2 gene in LSCC. RESULTS: The result of real-time PCR showed that the expression level of SH3GL2 mRNA in LSCC tissue was apparently down-regulated; immunohistochemical analysis showed that SH3GL2 protein was mainly located in cytoplasm, the rate of positive cells and SH3GL2 protein expression level were fluctuated with the pathological classification of LSCC; the result of Western blotting showed that SH3GL2 protein was down-regulated significantly in LSCC samples, especially in metastatic lymph nodes. CONCLUSIONS: These results suggest that SH3GL2 is a LSCC related gene and its expression level is fluctuated with the pathological classification which indicate that SH3GL2 participates in the development and progression of LSCC. And it may be considered as a novel tumor marker to find both a new anti-oncogene and relative factors of invasion and metastasis of laryngeal carcinoma.

Average-12.9 chromosome imbalances coupling with 15 differential expression genes possibly involved in the carcinogenesis, progression and metastasis of supraglottic laryngeal squamous cell cancer.

OBJECTIVE: With the objective of discovering novel putative chromosomal regions and special genes involved in the carcinogenesis, progression and metastasis of laryngeal squamous cell cancer (LSCC). METHODS: DNA copy profile of LSCC were obtained and analyzed by comparative genomic hybridization (CGH) and a computerized digital image analysis system. cDNA microarray of LSCC was performed and the profile was analyzed by Hierarchical clustering. RESULTS: CGH analysis showed average-12.9 gains and losses of chromosomes in LSCC. Relatively high frequencies of gains were found at 3q15-21 (14/18), 5p12-13 (11/18), 8q22-24 (6/18), 11q12-13 (8/18), 15q21-23 (7/18) and 18p11 (8/18), while those of losses at 1p13-21 (8/18), 3p21-23 (14/18), 5q21-22 (14/18), 9p12-pter (11/18) and 13q21-31 (8/18). Hierarchical clustering analysis showed that the differentially expressed genes were segregated into three groups. Three genes differentially expressed in process I (normal tissue to cancer) and process II (cancer to lymph node metastasis), and the Cy5/Cy3 ratios of twelve genes were either higher than 5.0 or lower than 0.2 in process I or process II. The fifteen special genes were first reported possibly to be the relationships with LSCC. In particular, 4 genes of them, which were cytochrome C oxidase Va, PPBP, EPHX2 and PON1, were first reported to correlate with tumorigenesis. SH3GL2, which was one of the 15 special genes, was located at one of the special chromosome regions, 9p12-pter. CONCLUSION: The important genes and special chromosomal aberrances might provide us a clue for further investigation of carcinogenesis, progression and metastasis in LSCC.

[Mutation of p53 and overexpression of STK15 in laryngeal squamous-cell carcinoma].

OBJECTIVE: To explore the relationship between p53 gene mutations and STK15 abnormal expression in the development of human laryngeal squamous-cell carcinoma (LSCC). METHODS: LSCC tissues and matched normal tissues were taken during operation from 55 patients without previous chemotherapy or radiotherapy. Following polymerase chain reaction amplification direct sequencing single strand conformational polymorphism (PCR-SSCP) combined with silver staining were used to detect mutations of p53 gene in exons 7 and 8 (p53E7 and p53E8) using genomic DNA from 110 specimens including 55 LSCC tissues and 55 matched normal tissues. STK15 expression were evaluated by RT-PCR with beta-actin as internal control. RESULTS: The mutation rate of p53E7 was 30.9% (compared to normal tissues, chi(2) = 8.66, P < 0.01). There was no mutation in p53E8. In 38 of the 55 cases (69.1%), the STK15 mRNA expression level was higher than that of the paired normal tissue. The STK15 to beta-actin ratio of average density value was 1.22 +/- 0.49 in the cancer tissue, and 0.99 +/- 0.54 in the normal tissues (t = 4.539, P < 0.01). In 14 of the 17 cases (82.4%) with p53E7 mutations, the STK15 expression was higher than that of normal tissue. In the 38 cases with STK15 over-expression, p53E7 mutation was found in 14 cases (36.8%). The rate of concurrence of p53E gene mutations and STK15 over-expression (25.5%) was higher than that of only p53E gene mutations (chi(2) = 26.025, P < 0.01). CONCLUSION: There is significant association between p53 gene mutation and STK15 over-expression in laryngeal squamous-cell carcinoma.

[Comparative genomic hybridization analysis of laryngeal carcinoma].

In order to find out the genes involved in the tumorigenesis of laryngeal carcinoma, we analyzed 18 laryngeal carcinoma with comparative genomic hybridization. Results show that each one has different degree of variances, included gains and losses of partial and whole chromosome. Each case has 12.9 abnormal regions averagely; losses are more than gains, equal to 7.2 and 5.7 per case respectively. Main regions are gains in chromosomes 3q (78%), 5p (61%), 11q (56%), 1q (50%), 8p (44%), 8q (39%) and 15q (39%), and losses of 3p (70%), 5q (78%), 9p (67%), 13q (50%), 1p (44%) and 14q (39%). There are many specific gains and losses in several chromosomes,especially the increase of copy number karyotype in 1p13-21(8/18), 3p21-23 (14/18), 5p21-22 (14/18), 9p12-pter (10/18) and 13q21-31 (8/18), while the decrease in 1q11-21 (11/18), 3q15-21 (12/18), 8p22-24 (6/18), 11q12-13 (8/18), 15q21-23 (7/18), 18p11 (8/18) are the characteristic varieties. These results suggest that there are oncogene, tumor suppressor gene and other associated genes involved in the tumorigenesis.

[Expression and promoter methylation of Apaf-1 gene in laryngeal squamous cell carcinoma].

Loss of tumor suppressor genes and apoptosis-associated genes was common event in laryngeal squamous cell carcinoma (LSCC). Apaf-1 (apoptotic protease activating factor-1) is a key factor in cytochrome C-dependent apoptotic pathway. To investigate the effect of Apaf-1 in progression of LSCC, we analyzed Apaf-1 from DNA and RNA levels. Semi-quantitative RT-PCR analysis of Apaf-1 mRNA showed that over 40 percent of LSCCs (11/27) were low expression compared to the para-neoplastic laryngeal tissues (PNTs). The results of CGH indicated loss in 2 of 18 cases but no amplification on chromosome 12q22-23. The LOH frequencies of D12S327, D12S1657, D12S393, D12S1706, D12S346 on 12q22-23 were 18.2%, 13.6%, 18.2%, 22.2% and 16.6%, respectively in 72 matched samples of LSCCs and PNTs. Methylation-specific PCR displayed that all of 11 LSCCs, whose expression of Apaf-1 mRNA down-regulated, were methylated in promoter regions. In contrast, only 1 of 16 LSCCs with no changes in Apaf-1 mRNA levels was methylated (chi2 test, P=0.0001). The results implied that abnormal expression of Apaf-1 participates in the genesis of LSCCs and decreased expression of Apaf-1 mRNA were not mainly due to the deletion of Apaf-1 gene. The Apaf-1 DNA methylation in promoter region might contribute to the decreased transcription of Apaf-1 in LSCCs.