Loss of heterozygosity for chromosomes 16q in Wilms tumors predicts outcomes:A meta-analysis

BACKGROUND The research findings suggest that the prognosis of children with Wilms tumor(WT)is affected by various factors.Some scholars have indicated that loss of heterozygosity(LOH)on chromosome 16q is associated with a poor prognosis in patients with WT.AIM To further elucidate this relationship,we conducted a meta-analysis.METHODS This meta-analysis was registered in INPLASY(INPLASY2023100060).We systematically searched databases including Embase,PubMed,Web of Science,Cochrane,and Google Scholar up to May 31,2020,for randomized trials reporting any intrapartum fetal surveillance approach.The meta-analysis was performed within a frequentist framework,and the quality and network inconsistency of trials were assessed.Odds ratios and 95%CIs were calculated to report the relationship between event-free survival and 16q LOH in patients with WT.RESULTS Eleven cohort studies were included in this meta-analysis to estimate the relationship between event-free survival and 16q LOH in patients with WT(I^(2)=25%,P<0.001).As expected,16q LOH can serve as an effective predictor of eventfree survival in patients with WT(risk ratio=1.95,95%CI:1.52–2.49,P<0.001).CONCLUSION In pediatric patients with WT,there exists a partial correlation between 16q LOH and an unfavorable treatment prognosis.Clinical detection of 16q chromosome LOH warrants increased attention to the patient’s prognosis.

Loss of heterozygosity for loci on chromosome arms 1p and 10q in oligoden-droglial tumors: relationship to outcome and chemosensitivity

Oligodendroglial tumors frequently have deletions ofchromosomal loci on lp and l9q.Loas of heterozygosity(LOH)of chromosome 10 may be a negative prognostic factor.We reviewed 23 patients with oligodendroglial tumors,toevaluate the frequency of lp and 10q LOH and correlate with clinical outcome.Three loci(DlS402,DlSl 172,MCT118)on lp and 2 loci(Dl0S520 and D10S521)on 10q were analyzed for LOH using PCR techniques.

LOSS OF HETEROZYGOSITY OF ER GENE IN BREAST CANCER AND ITS CLINICAL SIGNIFICANCE

Objective: Clinically, the reason of resistance for breast cancer to endocrine therapy has not been well known. The current study attempted to examine loss of heterozygosity (LOH) on the estrogen receptor (ER) gene in breast cancer and its relationship to clinicopathologic findings. Methods: DNAs of tumor tissues and blood lymphocytes were collected from 40 cases of primary breast cancer patients and LOH were detected using the microsatellite repeat assay and combined with other ER immunohistochemical assays. Results: ER-positive staining was observed in 65% of breast cancer. Heterogeneity of ER expression was found. Seven of the patients (17.5%) showed LOH. In three of the seven cases, there was total loss, and there was a marked reduction in the intensity of signal in the other four cases. LOH was associated with histologic grade, occurring more frequently in ER-negative and lymph node metastasis group, but not with tumor size and patient ages. Conclusion: This result implied that LOH of the ER gene may have an important role in the progression of breast cancer. It was postulated that the lack of ER function induced by LOH may contributed to endocrine therapy resistance of breast cancer since the tumor clone would escape from the ER regulation, obtain growth predisposition and finally lost response to therapy.

LOSS OF HETEROZYGOSITY AT 17p13 IN GASTRIC CANCER AND COLORECTAL CANCER

Southern hybridization was done on DNA samples of22 gastric tumors and corresponding normal tissues, 14colorectal tumors and corresponding normal tissues by probe phs53B mapping at 17P13.1 and probe PYNZ22mapping at 17pl3.3 which were purchased from the American Type Culture Collection. RFLP heterozygosity was observed in 12 normal tissues of gastric cancers and 10 normal tissues of colorectal cancers. Among these informative tumors, 6(50%) cases of gastric cancers and 6(60%) cases of colorectal cancers showed the loss of beterozygosity at 17p13. Our results demonstrated that the inactivation of wild type p53 might be involved in the carcinogenesis of gastric cancers and colorectal cancers.Furthermore, the mode of inactivation of p53 was in accord with the 'two hits' hypothesis by Anudson. The signincance was discussed regarding the presence of LOH detected by probe PYNZ22 mapping at 17pl3.3.

LOSS OF HETEROZYGOSITY FOR MARKERS ON 22 CHROMOSOME IN SPORADIC SCHWANNOMA

Objective To analyze the loss of heterozygosity (LOH) for markers on chromosew 22 (CHR 22 ) and its significance with their clinical behaviors. Methods The frequency of CHR22 LOH in 36 schwannomas was observed by denatured polyacrylamide gels and silver staining, and the proliferative index of schwannoma wes calculated by Ki-67 and PCNA immunohistochemistry. Results 15 schwannomas (41. 6% ) shawed allele lass. The proliferative index of schwannomas with LOH were significantly higher than those without LOH (P< 0. 05). In acoustic neuromas, patients with LOH were younger at the age of diagnosis, larger size of tumor, shorter history and higher growth rate than those without LOH, but with no significance. Conclusion CHR22 IDH was the frequent event in the tumorigenesis of sporadic schwannoma. There were some links beteen CHR22 LOH and clinical behavior.

The Loss of Heterozygosity of FHIT Gene in Sporadic Breast Cancer

function.FHIT is a potential tumor suppressor gene.Although the precise FHIT molecular mechanism of action is not well understood,evidences suggest that Fhit protein reduced levels are involved in mammary carcinogenesis.The aim of this study was to investigate if FHIT LOH could influence on sporadic breast cancer(BC)biological behavior,through its association with prognostic factors for sporadic BC.Tumor tissue and peripheral blood samples were analyzed using the microsatellite marker D3S1300.The findings were associated with clinicopathological parameters including overall survival.LOH was detected in 31.1%(52/167)of the informative BC’cases.Considering clinical and pathological characteristics we have found no significant association with FHIT LOH status.The mean follow-up time was 80 months.After the Cox regression analysis two parameters remained associated with BC’s risk of death:TNM stage III and IV-HR=3.74(95%CI,1.16-12.1)P=0.027 and disease relapse HR=3.14(CI 95%1.26-7.80)P=0.014.This study shows that FHIT LOH by itself is not a prognostic factor for sporadic BC.Further researches are required to elucidate the functional role of FHIT LOH concerning to BC.

Genetic aberration in primary hepatocellular carcinoma:correlation between p53 gene mutation and loss-of-heterozygosity on chromosome 16q21-q23 and 9p21-p23

To elucidate the molecular pathology underlying the development of hepatocellular carcinoma (HCC), we used 41 highly polymorphic microsatellite markers to examine 55 HCC and corresponding non-tumor liver tissues on chromosome 9, 16 and 17. Loss-of-heterozygosity (LOH) is observed with high frequency on chromosomal region 17p13 (36/55, 65%), 9p21-p23 (28/55, 51%), 16q21-q23 (27/55, 49%) in tumors. Meanwhile, microsatellite instability is rarely found in these microsatellite loci. Direct sequencing was performed to detect the tentative mutation of tumor suppressor genes in these regions: p53, MTS1/p16, and CDH1/E-cadherin. Within exon 5-9 of p53 gene, 14 out of 55 HCC specimens (24%) have somatic mutations, and nucleotide deletion of this gene is reported in HCC for the first time. Mutation in MTS1/pl6 is found only in one tumor case. We do not find mutations in CDH1/E-cadherin. Furthermore, a statistically significant correlation is present between p53 gene mutation and loss of chromosome region 16q21q23 and 9p21-p23, which indicates that synergism between p53 inactivation and deletion of 16q21-q23 and 9p21-p23 may play a role in the pathogenesis of HCC. Genetic aberration in hepatocellular

Loss of heterozygosity on chromosome 22 in sporadic schwannoma and its relation to the proliferation of tumor cells

Background Schwannoma is the tumor arising mainly from the cranial and spinal nerves. Bilateral vestibular schwannoma is the hallmark of neurofibromatosis type 2 （NF2）. The NF2 gene has been cloned with comprehensive analysis of its mutations in schwannoma. However, most studies focused on vestibular schwannoma. There are differences in proliferation of tumor cell and uhrastructure between vestibular and spinal schwannomas. It is unknown whether genetic alterations in vestibular schwannoma are different from those in non-vestibular schwannoma. We analyzed the loss of heterozygosity （LOH） on chromosome 22 in patients with sporadic schwannoma including vestibular and spinal schwannomas and correlated this genetic alteration with tumor proliferation. Methods In 54 unrelated patients without clinical NF1 or NF2, 36 patients had sporadic vestibular schwannoma, and 18 dorsal spinal root schwannoma. Four highly polymorphic linkage to NF2 gene microsatellite DNA markers （D22S264, D22S268, D22S280, CRYB2） were used to analyze LOH. The proliferative index was evaluated by Ki-67 and proliferative cell nuclear antigen （PCNA） immunostaining. Student＇s t test was used to analyze the difference of the proliferative index between schwannoma with LOH and that without LOH. The difference of the frequency of LOH in vestibular and spinal schwannomas was investigated by the chi-square test. Results Twenty-three schwannomas （42. 6% , 23/54） showed allele loss. The frequency of LOH in vestibular schwannoma was significantly higher than that in spinal schwannoma （ X^2 = 5.14, P 〈 0.05 ）. The proliferative index of schwannoma with LOH was significantly higher than that without LOH （tki-67 = 2. 97, P= 0. 0045 ; tPCNA =2.93, P =0. 0051）. Conclusions LOH on chromosome 22 is a frequent there is a correlation between LOH on chromosome 22 event in the tumorigenesis of sporadic schwannoma. And, and proliferative activity in schwannoma. The frequency of LOH in vestibular schwannoma is significantly different from that in spinal schwannoma.

p53 mutation, EGFR gene amplification and loss of heterozygosity on chromosome 10, 17?p in human gliomas

To further illustrate the roles of p53 gene, epidermal growth factor receptor (EGFR) gene and loss of heterozygosity (LOH) on chromosome 10 and 17?p in human glioma progression Methods p53 mutations were scanned in 50 gliomas with various malignant grades using the polymerase chain reaction single strand conformation polymorphism (PCR SSCP) assay, and were confirmed by direct sequencing LOH for chromosome 10, 17?p and amplification of the EGFR gene were also assessed using Southern blot analysis Results p53 mutations were found in 9 of 17 high grade astrocytomas (53%), 1 of 15 low grade astrocytomas (7%), and the only subject of eppendymoblastoma but in none of the 10 medulloblastomas and 7 eppendymomas The majority of gliomas (38/50) analyzed here retained both 17?p alleles The frequency of p53 mutations was 13% in this group of tumors and increased to 50% (6/12) in tumors with one 17?p allele ( P <0 025) LOH on chromosome 10 was found in 35% (6/17) of high grade astrocytomas, in 10% (1/10) of medulloblastomas, but in 0% of low grade gliomas EGFR gene amplification was found in 9 high grade gliomas, 60% (6/9) of which also presented LOH for chromosome 10 Conclusions These results indicate that p53 inactivation is a common genetic event in astrocytoma progression that may be more strongly associated with the progression of astrocytomas than with their origin Absence of p53 mutations in 50% of the tumors with one 17?p allele suggests that a tumor suppressor gene other than p53 may be located on chromosome 17?p and involved in progression to malignancy of some gliomas The loss of alleles on chromosome 10 and the amplification of the EGFR gene appear to be restricted to high grade tumors, suggesting that these events may be related to tumor progression rather than initiation

Detailed deletion mapping of loss of heterozygosity on 9p13-23 in laryngeal squamous cell carcinoma by microsatellite analysis

Background This study was designed to investigate the hot spots of microsatellite loss of heterozygosity (LOH) on 9p13-23 in laryngeal squamous cell carcinoma and to find out the correlation between the incidence of microsatellite LOH and the clinicopathological parameters Methods Tumor tissues were obtained from paraffin embedded sections with microdissection Genomic DNA was extracted from tumor tissues and peripheral blood lymphocytes with the phenol-chloroform Polymerase chain reaction (PCR) amplification and denaturing gel electrophoresis were carried out in a set of 42 squamous cell carcinoma (SCC) of larynx and corresponding peripheral blood lymphocytes using 13 highly polymorphic microsatellite markers on 9p13-23 The correlation was analyzed between microsatellite LOH at the high frequency on 9p13-23 and clinicopathological parameters in the patients with squamous cell carcinoma of larynx KH*2/5DResults Of the 42 laryngeal cancers, 41 (97 6%) showed LOH in at least one of the microsatellite markers tested on 9p13-23 The most frequently deleted marker was D9S162 in 17 of the 19 (89 5%) informative samples The marker D9S171, which is located on 9p21, had LOH detected in 12 of the 15 informative cases (80 0%) LOH at the D9S1748 marker (closest to the p16 gene locus) was detected in 18 of the 36 informative cases (50 0%) Allelic deletion mapping revealed two minimal regions of LOH encompassing markers D9S161-D9S171 on 9p21 and IFNA-D9S162 on 9p22-23 Multiple LOH (≥4) on 9p21-23 was found more frequently in the patients under 60 years, with supraglottic SCC or cervical lymph node metastasis than those over 60 years, with glottic SCC or without cervical lymph node metastasis ( P <0 01 or 0 01, 0 05, respectively) On the contrary, there was no correlation between T stages or pathologic classification and the frequency of LOH on 9p21-23 in 42 SCC of Larynx Conclusions These findings imply the presence of at least two putative tumor suppressor genes on 9p13-23 in laryngeal SCC Multiple genetic alterations are probably implicated in supraglottic SCC with cervical lymph node metastasis in younger patients

Analysis of two single nucleotide polymorphisms and loss of heterozygosity detection in the VHL gene in Chinese patients with sporadic renal cell carcinoma

Renal cell carcinoma （RCC） is the most common malignant tumour in the adult kidney. Recent studies have shown that inactivation of the tumour suppressor gene VHL located in chromosome 3p25-26 region is responsible for sporadic RCCs. According to Kundson＇s two hit theory, the mechanism of inactivation of a tumour suppressor gene involves mutation, hypermethylation and loss of heterozygosity （LOH）.

High frequency loss of heterozygosity in the region of the DBH locus in bladder cancer

Objective To determine the location of a putative tumor suppressor gene (TSG), and evaluate the frequency loss of heterozygosity (LOH) of the long arm of chromosome 9 (9q) in bladder cancer Methods We analyzed 25 patients with bladder cancer for LOH of 9q using 25 high density microsatellite markers Results Twenty three samples (92%) showed LOH at least at one locus on 9q We identified that the commonly deleted region were at 9q12 q21, 9q22, and 9q34 The rate of LOH was 44 0%, 22 7%, 22 7%, 16 0%, 12 0% on DBH, D9S15, D9S1815, D9S1831, D9S176 locus, respectively, and was not significantly related with grades and stages of tumor Conclusion These data suggest that alteration of a TSG at DBH of 9q may play an important role in the development of bladder cancer

Loss of chromosome 9p21 and decreased p16 expression correlate with malignant gastrointestinal stromal tumor

AIM: To investigate loss of heterozygosity (LOH) of chromosome 9p21 and the prognostic relevance of p16 expression in gastrointestinal stromal tumor (GIST). METHODS: Fifty-one GIST patients (30 men and 21 women; median age 59 years; range 29-80 years) treated surgically within a 10-year period were grouped by aggressive behavior risk (17 with very low and low, 14 intermediate, and 20 high risk). GISTs were characterized immunohistochemically and evaluated for LOH of 9p21 by microsatellite analysis at D9S1751, D9S1846, D9S942, and D9S1748. LOH of 9p21 and immunohistochemicalexpression of p16 protein encoded at 9p21 were correlated with clinicopathological parameters, and the prognostic significance of p16 alterations was evaluated. RESULTS: Thirty-one (63.3%) cases showed LOH with at least one microsatellite marker. LOH frequency was 37.0% at D9S1751, 37.5% at D9S1846, 42.1% at D9S942, and 24.2% at D9S1748. There was a higher LOH frequency of D9S942 in high-risk than in non-highrisk tumors (P < 0.05, χ 2 = 4.47). Gender, age, tumor size and site were not correlated with allelic loss. Ninety percent (18/20) of the GIST patients in the high risk group showed LOH with at least one of the 9p21 markers, while 57.1% (8/14) in the intermediate risk group and 33.3% (5/15) in the very low and low risk groups, respectively (P < 0.05, χ 2 = 12.16). Eight (28.5%) of 31 patients with LOH and 1 (5.6%) of 18 patients without LOH died of the disease during the follow-up period. Loss of p16 protein expression occurred in 41.2%, but in 60% of the high risk group and 23.5% of the very low and low risk groups (P < 0.05, χ 2 = 4.98). p16 loss was associated with poor prognosis (P < 0.05, χ 2 = 4.18): the 3and 5-year overall survival rates were 84.8% and 70.8% for p16-negative and 100% and 92.0% for p16-positive patients, respectively. CONCLUSION: LOH at 9p21 appears to play an important role in GIST progression; decreased p16 expression in GIST is highly predictive of poor outcome.

LOH analysis of genes around D4S2964 identifies ARD1B as a prognostic predictor of hepatocellular carcinoma

AIM:To investigate genes around the locus D4S2964 affected by loss of heterozygosity(LOH) and their clinical implications.METHODS:Four hundred and forty single nucleotide polymorphisms(SNPs) located at 49 genes around D4S2964 were selected from the National Center for Biotechnology Information website for the SNPs microarray fabrication.LOH of SNPs markers in 112 cases of hepatocellular carcinoma(HCC) tissues and paired adjacent liver tissues were investigated by the SNPs microarray.The correlation between allelic losses with clinicopathological features and overall survival was analyzed.RESULTS:A f ine map of LOH of SNPs in genes around D4S2964 was plotted.The average frequency of LOH in genes was 0.39.A correlation between cirrhosis and the FAL index(fractional allelic loss) was found(P = 0.0202).Larger tumor size was found to be signif icantly associated with LOH in genes ADP-ribosyltransferase 3(ART3),nucleoporin 54 kDa(NUP54),scavenger receptor class B,member 2(SCARB2) and coiled-coil domain containing 158(CCDC158)(P = 0.043,P = 0.019,P = 0.001,P = 0.037,respectively).Kaplan-Meier analysis showed that patients with LOH in ARD1 homolog B(ARD1B) and septin 11(SEPT11) had a significantly lower survival rate than those with retention(P = 0.021 and P = 0.004,respectively).A Cox regression model suggested that LOH in ARD1B and SEPT11,respectively,were predictors of the overall survival in HCC(P = 0.006 and P = 0.026,respectively).CONCLUSION:LOH in genes around D4S2964 may play an important role in HCC development and progression.LOH in ARD1B and SEPT11 could serve as novel prognostic predictors in HCC patients.

Prognostic values of chromosome 18q microsatellite alterations in stage Ⅱ colonic carcinoma

AIM: To investigate the prognostic value of chromosome 18q microsatellite alterations (MA) in stage Ⅱ colon cancer. METHODS: One hundred and six patients with sporadic stage Ⅱ colon cancer were enrolled in this study. DNA was extracted from formalin-fixed, paraffin-embedded tumor and adjacent normal mucosal tissue samples. MA, including loss of heterozygosity (LOH) and microsatellite instability (MSI), was analyzed by polymerase chain reaction, polyacrylamide gel-electrophoresis and DNA sequencing at 5 microsatellite loci on chromosome 18q (D18S474, D18S55, D18S58, D18S61 and D18S64).RESULTS: Among the 102 patients eligible for MA information, the overall frequencies of LOH, high and low frequency MSI/microsatellite stable were 49.0%, 17.6% and 82.4%, respectively. The high frequency of 18q-LOH was signif icantly associated with the poor 5-year overall survival (OS) (P=0.008) and disease free survival (P=0.006). High levels of MSI were significantly associated with a longer 5-year OS (P=0.045) while the higher frequency of 18q-LOH at the loci of D18S474 and D18S61 was significantly associated with a poorer 5-year OS (P=0.010 and 0.005, respectively). But multivariate analysis showed that only the frequency of 18q-LOH was significantly associated with the prognosis of the disease. CONCLUSION: High frequency of 18q-LOH is an independent prognostic factor indicating poor prognosis of the patients with stage Ⅱ colon cancer.

Correlation of genomic and expression alterations of AS3 with esophageal squamous cell carcinoma

Androgen-induced proliferation shutoff gene AS3, also known as APRIN, is a growth inhibitory gene that is initially implicated in prostate cancer. This gene is required for androgen-dependent growth arrest and is a primary target for 1,25（OH）2D3 and androgens. Allelic loss at AS3 locus has been linked to a variety of cancers. However, the correlation of genomic and expression alterations of AS3 with esophageal squamous cell carcinoma （ESCC） is not well established. In this study, the genornic and expression alterations of AS3 in ESCC and their clinical significance are evaluated. Loss of heterozygosity （LOH） analysis using an AS3 intragenic microsatellite marker D13S171 revealed 72% allelic loss at AS3 locus in ESCC, which is significantly correlated with higher pathological grade （P=0.042）. RT-PCR examination showed that AS3 mRNA obviously decreased in 44% tumors and its down-regulation was correlated with the sex of patients （P=0.03）. Furthermore, the correlation between genornic and expression alterations of AS3 gene was analyzed in 18 ESCC specimens, which indicated that the consistency between allelic loss and decreased mRNA expression of AS3 was relatively poor. The results of this study indicate that the aberrant expression of AS3 may be involved in the tumorigenesis of esophagus and is responsible for the male predominance of ESCC.

Relationship between Microsatellite Alterations of RASSF1A Gene and Development of Cervical Carcinoma

Objective： To explore the relationship between microsatellite alterations of RASSFIA gene and the development of cervical carcinoma, and its relationship with HPV16 infection. Methods： Two sites of microsatellite polymorphism of RASSFIA gene were selected. Polymerase chain reaction （PCR） technique was used to detect LOH and MSI in 50 cases of cervical carcinoma and 40 cases of cervical intraepithelial neoplasia （CIN）, and to detect the infection state of HPV16. Results： At D3S1478 and D3S4604, the LOH rates of cervical carcinomas were 32.6% （14/43） and 48.9% （23/47）, the MSI rates were 14% （6/43） and 19.1% （9/47）, respectively. The LOH rates of CINs were 31.4% （11/35） and 39.5% （15/38）, the MSI rates were 11.4% （4/35） and 15.8% （6/38）, respectively. There were no significant differences between cervical carcinomas and CINs in respect to their positive rates of LOH and MSI at D3S1478 and D3S4604 （P〉0.05）. There were significant differences in LOH rates at D3S1478 and D3S4604 between the stage Ⅰ-Ⅱ and Ⅲ-Ⅳ cervical carcinomas and between the well/moderately differentiated cervical carcinomas and the poorly differentiated cervical carcinomas （P〈0.05）. The positive rates of LOH and MSI for CIN Ⅲ and noninvasive cervical carcinomas were higher than those in CIN Ⅰ-Ⅱ. The rates of infection of HPV16 in cervical cancer was obviously higher than that in CIN and in normal cervical tissues （P〈0.05）, and the incidence of LOH of RASSFIA gene was higher in HPV16（＋） than that in HPV16（-） （P〈0.05）. Conclusion： The RASSFIA gene change is a relatively late event in cervical carcinomas. The detection of LOH and MSI of RASSFIA gene might be helpful to the early diagnosis and the screening of cervical carcinoma. It might also be useful for predicting the prognosis of cervical carcinoma.

FREQUENT ALLELIC IMBALANCE AND CYTOGENETIC DELETION ON THE SHORT ARM OF CHROMOSOME 1 IN NASOPHARYNGEAL CARCINOMA

Objective: To construct a fine map of the loss of chromosome lpter-p36.11 region in nasopharyngeal carcinoma (NPC) using PCR-LOH technique. Methods: DNA extracted from separated cancerous cells and their mated noncancerous lymphocytes from 47 cases of NPC biopsies were analyzed by means of PCR-LOH to detect 20 loci spanning chromosome lpter-p36.11 region in NPC. Results: In 47 NPC cases, 37 (82.2%) cases showed at least one loci LOH. The highest frequency of less of heterozygosity (LOH) at all 20 loci was found at loci DIS234 (50. 0%) on lp36.13 and loci DlS2644 (37.5%) on lp36.22. There was a statistically significant difference between DlS234 LOH frequency (60%, 9/15) in early stage and that (50. 0%, 8/16) in advanced stage (P>0.05). Of all 20 STSs (sequence tqgged-site, STS), DIS243 (37.5%) and DIS199 (30.2%) showed the highest frequency of MI (microsatellite instability) on lp36.33 and lp36.21, respectively. In addition, several cases showed a contiguous stretch of allelic loss in a different level. Conclusion: Two minimal deletion regions (MDR) on the short arm of chromosome 1 were seated at lp36.13 (DIS234, 2.0 cm) and lp36.22 (DIS436-DIS2644, 6.3 cm) respectively, indicating that one or more candidate tumor suppressor gene (TSG) in the two regions may be involved in NPC pathogenesis in an early clinical stage.

GENETIC ALTERRATIONS OF MICROSATELLITE MARKERS ATCHROMOSOME 17 IN NON-SMALL CELL LUNG CANCER

Objective: To analyse the microsatellite instability (MI) and loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). Methods: MI and LOH at chromosome 17 were checked in 35 cases of NSCLC tumor-normal paired tissues using four microsatellite markers TP53 (17pl3.1), THRA1 (17qll.2–12), D17S579 (17ql2–21) and D17S855 (17q21) by PCR based analysis. Mutations of P53 exons 5–8 were also tested using PCR-single strand conformation polymorphism (PCR-SSCP) and PCR-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Results: 22 of 35 tumors (62.8%) displayed MI or LOH. 14 tumors (40.0%) exhibited MI, 11 tumors (31.4%) exhibited LOH, while 3 tumors (8.6%) exhibited MI and LOH concurrently. 23 tumors (65.7%) exhibited P53 gene mutations. The frequency of MI or LOH was obviously higher in the early-stage (stages I and II, 78.9%) than in the advanced-stage (stage III, 43.8%). However, the frequency of MI or LOH had no difference either between high-grade (75.0%) and low-grade (52.6%) differentiated NSCLC or between the tumors with P53 mutations (59.1%) and those without P53 mutations (69.2%). No relationship was observed between the presence of MI or LOH and the histologic subtype of NSCLC. Conclusion: The results suggest that MI and LOH at chromosome 17 may play a significant role in the development of NSCLC. The high frequency of MI or LOH in the early-stage tumors indicates that these genetic alterations could occur early during NSCLC development. Our data also show that the genetic alterations of microsatellite at chromosome 17 was not associated with P53 gene mutations.

Detailed Deletion Mapping of Chromosome 9p21-22 in Nasopharyngeal Carcinoma

Objective: To further refine the extent of deletion on chromosome 9p21-22 in nasopharyngeal carcinoma (NPC) and provide evidence for discovering new tumor suppressor gene. Methods: Loss of heterozygosity (LOH) on chromosome 9p21-22 was analyzed in 25 paired blood and tumor samples by using 11 high-density microsatellite polymorphic markers. Results: 17 of 25 cases (68.0%) showed LOH at one or more loci. Higher frequencies of LOH were found at four loci: D9S161 (35.0%), D9S1678 (31.5%), D9S263 (33.3%) and D9S1853 (33.3%), where 6 cases had a contiguous stretch of allelic loss. Conclusion: The minimal common region of deletion might be defined between D9S161 and D9S1853 (estimated about 2.7 cM in extent) at 9p21.1, suggesting that inactivation of one or more tumor suppressor genes located in this region may be an important step in NPC.