Preclinical evaluation of the VEGF/Ang2 bispecific nanobody BI 836880 in nasopharyngeal carcinoma models.

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is endemic to parts of Asia and overexpression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α are common in NPC. Anti-vascular agents have known clinical activity in patients with recurrent/ metastatic NPC and in this study, we investigated the anti-tumor effect of BI 836880, a humanized bispecific nanobody against VEGF and angiopoietin-2 (Ang2), in preclinical models of EBV-positive and EBV-negative NPC. The efficacy of BI 836880 was also compared with bevacizumab, a recombinant humanized monoclonal antibody against VEGF. We found that BI 836880 could exert growth-inhibitory effect on endothelial cells (HUVEC-C) and the EBV-negative NPC cell line (HK1), but to a lesser extent in the EBV-positive NPC cell lines, C17C and C666-1. In patients-derived xenograft (PDX) models of NPC - Xeno-2117 and Xeno-666, BI 836880 could suppress tumor growth and Ki67, as well as induce tumor necrosis and reduce microvessel density. Moreover, treatment with BI 836880 increased the level of macrophage infiltration in both PDX tumor models of NPC, suggesting that BI 836880 may exert immunomodulatory effect on the NPC immune microenvironment. When compared with bevacizumab, BI 836880 appeared to show at least comparable activity as bevacizumab in terms of its anti-proliferative and anti-angiogenic effects. This study showed that BI 836880 has anti-proliferative, anti-angiogenic and possibly immunomodulatory effect in clinical models of NPC, therefore the dual targeting of VEGF and Ang2 signaling in NPC should be further investigated.

Multicenter phase II study of the AKT inhibitor MK-2206 in recurrent or metastatic nasopharyngeal carcinoma from patients in the mayo phase II consortium and the cancer therapeutics research group (MC1079).

BACKGROUND: This study investigated the activity of MK-2206, an AKT inhibitor, in metastatic or recurrent nasopharyngeal carcinoma (NPC). METHOD: Oral MK-2206 at a dose of 200 mg was administered on days 1, 8, 15 and 22 of a 28-day cycle until progression. Plasma EBV DNA clearance during the first month of treatment was measured, and archived tumors were analyzed for the expression of AKT and PIK3CA mutation and PIK3CA amplification. The dual primary endpoint was objective response rate and 6-month progression-free survival (PFS) rate. RESULTS: 21 patients were enrolled and one patient achieved a partial response (5 %) and 11 had stable disease (52 %), with a median PFS of 3.5 months (95 % confidence interval, CI: 0.9-7.3). The 6-month PFS rate was 43 % (95 % CI: 22-66 %) and the median OS was 10 months (95 % CI: 5.9 months-not reached). Seven patients (33 %) experienced grade 3 toxicities which could be related to MK-2206. Macular-papular rash was the most common (n = 6), followed by hyperglycemia (n = 2) and fatigue (n = 1). In the 12 tumor samples analyzed, PIK3CA amplification was detected in one patient's primary NPC, who had SD lasting over 12 months. Patients with decreasing EBV DNA values over time were more likely to be alive and progression-free for at least 6 months than those without a decrease (p = 0.001). CONCLUSION: The study was terminated due to the limited activity observed in this heavily pre-treated group of patients. Further studies are needed to elucidate the optimal way of selecting patients for AKT inhibitors.

Scrotal antegradesclerotherapy demonstrates anatomical variations on venous drainage in paediatric, adolescent and young adult varicoceles.

AIM OF THE STUDY: Anatomical variations on venous drainage in varicoceles are under-reported. We report our experience in scrotal antegrade sclerotherapy (SAS) for adolescent varicoceles. METHODS: Since 2011, 15 consecutive boys with left varicoceles were recruited. Under general anaesthesia, a 5-mm transverse incision was made at scrotal neck, testicular vein was cannulated at pampiniform plexus with venogram performed. Foam sclerosant by mixing sodium tetradecyl sulphate (STS), Lipiodol(®) and air was slowly injected under fluoroscopy. Postoperatively the patients were followed-up for varicocele grading, testicular size, and complications. MAIN RESULTS: Median age at operation was 14 (10-19) years. 80 % had grade three varicoceles, 33.3 % had smaller left testis before operation. Intra-operative venogram showed three different anatomical variations. Group I: eleven patients (73.3 %) had single distinct internal spermatic vein; Group II: two patients demonstrated duplication of internal spermatic vein draining into left renal vein; Group III: two patients had pampiniform plexus draining to iliac and/or paraspinal veins. SAS was performed in Group I and II patients. Sclerosant volume injected ranged from 1.5 to 4.5 ml. In Group III patients, surgical ligation of testicular veins was performed rather than SAS to avoid uncontrolled systemic sclerosant spillage. Mean length of stay was 1.13 day. One patient with scrotal haematoma and one other with minor wound dehiscence were managed conservatively. Mean follow-up period was 10.9 (1-22) months. Thirteen patients (86.7 %) achieved varicocele grading ≤ 1. There was no postoperative testicular atrophy, hydrocele and epididymo-orchitis. CONCLUSION: Scrotal antegrade sclerotherapy using STS foam is a safe and effective treatment for adolescent varicoceles. Anatomical variations on venous drainage in varicoceles are common.

Development of the hybrid Sleeping Beauty: baculovirus vector for sustained gene expression and cancer therapy.

Antiangiogenesis is an appealing anticancer approach but requires continued presence of the antiangiogenic agents, which can be remedied by gene therapy. Baculovirus is an emerging gene delivery vector but only mediates transient expression (<7 days); thus, this study primarily aimed to develop a hybrid baculovirus for sustained antiangiogenic gene expression and cancer therapy. We first constructed plasmids featuring adeno-associated virus inverted terminal repeats (AAV ITRs), oriP/Epstein-Barr virus-expressed nuclear antigen 1 (EBNA1) or Sleeping Beauty (SB) transposon and compared their efficacies in terms of persistent expression. In human embryonic kidney (HEK293) cells, AAV ITR failed to prolong the expression while oriP/EBNA1 moderately extended the expression to 35 days. In contrast, the SB system led to stable expression beyond 77 days even without antibiotic selection. Given this finding, we constructed a hybrid SB baculovirus expressing the SB transposase and harboring the transgene cassette flanked by inverted repeat/direct-repeat (IR/DR) elements recognizable by SB. The hybrid SB baculovirus efficiently transduced mammalian cells and mediated an expression duration longer than that by conventional baculoviruses, thanks to the transgene persistence and integration. The SB baculovirus (Bac-SB-T2hEA/w) expressing the antiangiogenic fusion protein comprising endostatin and angiostatin (hEA) also enabled prolonged hEA expression. With sustained hEA expression, Bac-SB-T2hEA/w repressed the angiogenesis in vivo, hindered the growth of two different tumors (prostate tumor allografts and human ovarian tumor xenografts) in mice and extended the life span of animals. These data altogether implicated the potential of the hybrid SB-baculovirus vector for prolonged hEA expression and for the treatment of multiple types of angiogenesis-dependent tumors.

Dysregulation of microRNA-204 mediates migration and invasion of endometrial cancer by regulating FOXC1.

MicroRNAs (miRNAs) regulate mRNA stability and protein expression, and certain miRNAs have been demonstrated to act either as oncogenes or tumor suppressors. Differential miRNA expression signatures have been documented in many human cancers but the role of miRNAs in endometrioid endometrial cancer (EEC) remains poorly understood. This study identifies significantly dysregulated miRNAs of EEC cells, and characterizes their impact on the malignant phenotype. We studied the expression of 365 human miRNAs using Taqman low density arrays in EECs and normal endometriums. Candidate differentially expressed miRNAs were validated by quantitative real-time PCR. Expression of highly dysregulated miRNAs was examined in vitro through the effect of anti-/pre-miRNA transfection on the malignant phenotype. We identified 16 significantly dysregulated miRNAs in EEC and 7 of these are novel findings with respect to EEC. Antagonizing the function of miR-7, miR-194 and miR-449b, or overexpressing miR-204, repressed migration, invasion and extracellular matrix-adhesion in HEC1A endometrial cancer cells. FOXC1 was determined as a target gene of miR-204, and two binding sites in the 3'-untranslated region were validated by dual luciferase reporter assay. FOXC1 expression was inversely related to miR-204 expression in EEC. Functional analysis revealed the involvement of FOXC1 in migration and invasion of HEC1A cells. Our results present dysfunctional miRNAs in endometrial cancer and identify a crucial role for miR-204-FOXC1 interaction in endometrial cancer progression. This miRNA signature offers a potential biomarker for predicting EEC outcomes, and targeting of these cancer progression- and metastasis-related miRNAs offers a novel potential therapeutic strategy for the disease.

Role of STAT3/5 and Bcl-2/xL in 2-methoxyestradiol-induced endoreduplication of nasopharyngeal carcinoma cells.

2-methoxyestradiol (2ME2), an endogenous metabolite of 17-ß-estradiol, has been shown to induce apoptosis and cell cycle arrest in various tumor models. We have previously shown that 2ME2 induced endoreduplication in a well-differentiated nasopharyngeal carcinoma (NPC) HK-1 and a poorly differentiated C666-1 cell line. In the present study, we studied the survival factors involved in 2ME2-induced endoreduplicating NPC cells. In the HK-1 cells, knockdown of BcL-xL expression by siRNA resulted in the reduction of endoreduplication and an increase in the percentage of apoptosis. Further mechanistic study revealed that 2ME2 enhanced the expression of the phosphorylated form of STAT5 (p-STAT5-Y694), but not p-STAT3 (Y705) and p-STAT3 (S727), in the nucleus of HK-1 cells. Pre-treatment of cells with JAK/STAT inhibitor AG490 and STAT5 inhibitor resulted not only in the reduced expression of Bcl-xL, but also reduced the percentage of endoreduplicating cells. In contrast, 2ME2 enhanced the expression of p-STAT3 in the poorly differentiated C666-1 cells. Pharmacological inhibition of STAT3 or Bcl-2/xL resulted in a decrease in endoreduplication of C666-1 cells. Taken together, the expression of p-STAT5 and p-STAT3 was upregulated in 2ME2-induced endoreduplicating HK-1 and C666-1 cells, respectively. Combination of 2ME2 with Bcl-2/xL inhibitor is a novel strategy to reduce the formation of endoreduplicating cells during chemotherapeutic treatment of NPC. © 2011 Wiley Periodicals, Inc.

Latent membrane protein 1 suppresses RASSF1A expression, disrupts microtubule structures and induces chromosomal aberrations in human epithelial cells.

Epstein-Barr virus (EBV) infection is closely associated with nasopharyngeal carcinoma (NPC) and can be detected in early premalignant lesions of nasopharyngeal epithelium. The latent membrane protein 1 (LMP1) is an oncoprotein encoded by the EBV and is believed to play a role in transforming premalignant nasopharyngeal epithelial cells into cancer cells. RASSF1A is a tumor-suppressor gene commonly inactivated in many types of human cancer including NPC. In this study, we report a novel function of LMP1, in down-regulating RASSF1A expression in human epithelial cells. Downregulation of RASSF1A expression by LMP1 is dependent on the activation of intracellular signaling of NF-kappaB involving the C-terminal activating regions (CTARs) of LMP1. LMP1 expression also suppresses the transcriptional activity of the RASSF1A core promoter. RASSF1A stabilizes microtubules and regulates mitotic events. Aberrant mitotic spindles and chromosome aberrations are reported phenotypes in RASSF1A inactivated cells. In this study, we observed that LMP1 expression in human epithelial cells could induce aberrant mitotic spindles, disorganized interphase microtubules and aneuploidy. LMP1 expression could also suppress microtubule dynamics as exemplified by tracking movements of the growing tips of microtubules in live cells by transfecting EGFP-tagged EB1 into cells. The aberrant mitotic spindles and interphase microtubule organization induced by LMP1 could be rescued by transfecting RASSF1A expression plasmid into cells. Downregulation of RASSF1A expression by LMP1 may facilitate its role in transformation of premalignant nasopharyngeal epithelial cells into cancer cells.

Identification of molecular markers and signaling pathway in endometrial cancer in Hong Kong Chinese women by genome-wide gene expression profiling.

Endometrial cancer is the third most common gynecologic malignancy and the ninth most common malignancy for females overall in Hong Kong. Approximately 80% or more of these cancers are endometrioid endometrial adenocarcinomas. The aim of this study was to reveal genes contributing to the development of endometrioid endometrial cancer, which may impact diagnosis, prognosis and treatment of the disease. Whole-genome gene expression analysis was completed for a set of 55 microdissected sporadic endometrioid endometrial adenocarcinomas and 29 microdissected normal endometrium specimens using the Affymetrix Human U133 Plus 2.0 oligonucleotide microarray. Selected genes of interest were validated by quantitative real-time-polymerase chain reaction (qRT-PCR). Pathway analysis was performed to reveal gene interactions involved in endometrial tumorigenesis. Unsupervised hierarchical clustering displayed a distinct separation between the endometrioid adenocarcinomas and normal endometrium samples. Supervised analysis identified 117 highly differentially regulated genes (>or=4.0-fold change), which distinguished the endometrial cancer specimens from normal endometrium. Twelve novel genes including DKK4, ZIC1, KIF1A, SAA2, LOC16378, ALPP2, CCL20, CXCL5, BST2, OLFM1, KLRC1 and MBC45780 were deregulated in the endometrial cancer, and further validated in an independent set of 56 cancer and 29 normal samples using qRT-PCR. In addition, 10 genes were differentially regulated in late-stage cancer, as compared to early-stage disease, and may be involved in tumor progression. Pathway analysis of the expression data from this tumor revealed an interconnected network consisting of 21 aberrantly regulated genes involved in angiogenesis, cell proliferation and chromosomal instability. The results of this study highlight the molecular features of endometrioid endometrial cancer and provide insight into the events underlying the development and progression of endometrioid endometrial cancer.

Identification of RASSF1A modulated genes in nasopharyngeal carcinoma.

RASSF1A is a tumor suppressor gene on 3p21.3 frequently inactivated by promoter hypermethylation in nasopharyngeal carcinoma (NPC). To identify RASSF1A target genes in NPC, we have investigated the expression profile of the stable RASSF1A transfectants and controls by high-density oligonucleotide array. A total of 57 genes showed differential expression in the RASSF1A-expressing cells. These RASSF1A target genes were involved in multiple cellular regulatory processes such as transcription, signal transduction, cell adhesion and RNA processing. The RASSF1A-modulated expression of eight selected genes with the highest fold changes (ATF5, TCRB, RGS1, activin betaE, HNRPH1, HNRPD, Id2 and CKS2) by RASSF1A was confirmed in both stable and transient transfectants. Compared with the RASSF1A transfectants, an inverse expression pattern of activin betaE, Id2 and ATF5 was shown in the immortalized nasopharyngeal epithelial cells treated with siRNA against RASSF1A. The findings imply that the expression of activin betaE, Id2 and ATF5 was tightly regulated by RASSF1A and may associate with its tumor suppressor function. Strikingly, overexpression of Id2 is common in NPC and RASSF1A-induced repression of Id2 was mediated by the overexpression of activin betaE. The results suggest a novel RASSF1A pathway in which both activin betaE and Id2 are involved.

Patients with malignant or pre-malignant cervical lesion have increased risk of becoming hepatitis B carrier.

Human Papillomavirus (HPV) and Hepatitis B virus (HBV) are known aetiology of cervical and hepatocellular carcinoma, respectively. Both diseases share a similar clinical course, that is, the vast majority of those infected by these two viruses can eradicate the viruses spontaneously. A small sub-group who fails to clear the virus becomes chronic carrier and can progress to carcinoma many years later. We postulated that patients with pre-malignant or malignant cervical lesion are at increased risk of becoming chronic HBV carrier if infected, which may be attributed to inherent immunological deficiency against viral infection. We tested HBV carrier status from 288 patients with cervical carcinoma, 242 patients with high grade cervical intra-epithelial neoplasia (CIN) and 311 women with neither of the above conditions as control subjects. The HBV carrier rate in the Cancer Group, CIN Group and Control Group was 21.4%, 24.1% and 10.6%. The carrier rate was significantly higher in both the Cancer Group (p<0.01) and the CIN Group (p<0.01), compared to the Control Group. Our study suggests that a common immunological mechanism is involved in eradication of HBV and HPV infections and inherent immuno-deficiency might lead to an association of HBV carrier status with cervical carcinoma. Further studies are needed to confirm our findings and delineate the mechanism involved.

Is aortic lymphadenectomy necessary in the management of endometrial carcinoma?

OBJECTIVE: To evaluate the role of aortic lymphadenectomy in the management of endometrial carcinoma. METHODS: Clinical notes of 163 patients with endometrial carcinoma were reviewed. All patients had peritoneal cytology, total abdominal hysterectomy, bilateral salpingo-oophorectomy and pelvic lymphadenectomy with or without aortic lymphadenectomy. RESULTS: Seventy-five (46.0%) patients had pelvic lymphadenectomy alone whereas 88 (54.0%) had both pelvic and aortic lymphadenectomy. Thirty-five (21.5%) patients had nodal metastases with positive pelvic and aortic nodes in 26 (16.0%) and 24 (27.3%) patients, respectively. Isolated aortic metastases were found in 17 cases (19.3%). Among 35 patients with nodal metastases, recurrence developed in 15 (42.9%) patients and all except one died within five to 50 months. The remaining patients had a median disease-free period of 55 months (13-93 months). The recurrence rate was higher (63.6%) among patients with upper aortic lymph node metastases, and all those who recurred died of disease within seven to 28 months. CONCLUSIONS: Our data suggest that aortic lymphadenectomy provides both diagnostic and therapeutic value in the management of endometrial carcinoma with high metastatic risk. After surgical removal and adjuvant radiotherapy, patients with nodal metastases achieved a better survival chance.

IKKα-mediated biogenesis of miR-196a through interaction with Drosha regulates the sensitivity of cancer cells to radiotherapy.

Retraction to: Cell Death Differ 2016;23(9):1471­1482. doi:10.1038/cdd.2016.32

Nucleases and adenosine 3',5'-cyclic monophosphate phosphodiesterase activities in murine sarcoma virus (Moloney)-infected mice.

To provide information on the role of nucleases in oncogenic virus infection, the activities of 3'-nucleotide phosphodiesterase (3'-NPDase), 5'-nucleotide phosphodiesterase (5'-NPDase), acid deoxyribonuclease (DNase II), and 3',5'-cyclic AMP phosphodiesterase (cAMPDase) in spleen extracts of murine sarcoma virus-infected C57BL/6 inbred mice were studied. At the peak of tumor growth and of the cell-mediated cytotoxic response (CMC) against tumor-associated antigens, 3'-NPDase, 5'-NPDase, and DNase II all showed depressed activities in the spleen, whereas the activity of cAMPDase in the spleen increased at the peak of CMC and remained elevated thereafter. Serum enzyme activities of the infected mice were also determined, and only 3'-NPD-ase in serum correlated well with CMC. Inasmuch as the correlation of the tumor growth with CMC was established in this system, further study on tumors with variance between CMC and growth is necessary to determine if serum 3'-NPDase is a useful biochemical marker for CMC in vivo.

p16 gene alterations in nasopharyngeal carcinoma.

In order to investigate the p16 gene alterations in nasopharyngeal carcinoma (NPC), we have examined for mutations and deletions of the p16 gene in samples of NPC including 3 cell lines, 3 xenografts, and 20 primary tumors with matched blood DNA as controls. Using single-strand conformation polymorphism and direct sequencing analysis, no p16 gene mutations were detected in the NPC primary tumors and xenografts. Mutations of the p16 gene were found in three NPC cell lines, but no normal allele was present in these samples. Homozygous deletion of the p16 gene has been identified in 2 (67%) of 3 cases of NPC xenografts and 7 (35%) of 20 cases of primary tumors by comparative multiplex PCR analysis. A homozygous deletion region distal to the p16 locus was observed in a case of NPC primary tumor. Our data document for the first time that alterations of the p16 gene were frequent in NPC and that homozygous deletion was the major mechanism for the inactivation of this gene. These findings suggest that complete inactivation of the p16 gene may play a role in the development of NPC. Moreover, inactivation of other putative tumor suppressor gene(s) outside of the p16 locus within chromosome 9p21-22 may also contribute to the pathogenesis of this disease.

5'-nucleotide phosphodiesterase isoenzyme in patients with hepatitis B infection.

The hypothesis that hepatitis B infection is etiologically related to hepatoma has been investigated by studying the interrelationships between hepatitis B surface antigen (HBsAg, Australia antigen) and the fast-moving 5'-nucleotide phosphodiesterase Band V isoenzyme (5'-NPDase-V). Sera from 58 patients with viral hepatitis were tested for 5'-NPDase-V and HBsAg. The isoenzyme was found in 34 of 37 patients who were also positive for HBsAg but in only 4 of 21 hepatitis patients who were HBsAg negative. Five patients convalescing from hepatitis were negative for both HBsAg and the isoenzyme. Preparative gel electrophoresis showed that these 2 markers were different proteins. Of 34 hepatoma patients, 29 were positive for 5'-NPDase-V. Only 1 isoenzyme-positive patient was positive for HBsAg by counterimmunoelectrophoresis. However, of 16 isoenzyme-positive hepatoma patients available for radioimmunoassay, 8 were NBsAg positive (50%). None of 21 hepatoma samples tested for antibody to NBsAg was positive. Of 21 "normal" carriers of HBsAg and 10 carriers with Down's syndrome, 4 persons were detected with the isoenzyme. The results suggest that HBsAg and 5'-NPDase-V in the presence of liver damage are associated and thus provide a new marker enzyme between hepatitis B infection and hepatoma.

High resolution allelotype of microdissected primary nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a common cancer in South China but is rare in other parts of the world. To better understand the molecular basis of this cancer, we performed high-resolution allelotyping on 27 microdissected primary tumors using 382 microsatellite markers. We have detected high frequencies of allelic imbalance on 3p (96.3%), 9p (85.2%), 9q (88.9%), 11q (74.1%), 12q (70.4%), 13q (55.6%), 14q (85.2%), and 16q (55.6%). Nonrandom allelic changes of 12q and 16q were revealed for the first time. In addition, loss of heterozygosity on chromosomal arms 1p (37.0%), 5q (44.4%), and 12p (44.4%) were also common in NPC. Multiple minimally deleted regions, 7-40 cM, were identified at 3p14-24.2, 11q21-23, 13q12-14, 13q31-32, 14q24-32, and 16q22-23. Frequent deletions of these minimally deleted regions implied the presence of tumor suppressor genes that may be involved in the development of NPC. Consistent loss of heterozygosity on 3p, 9p, and 14q in almost all tumors suggested that such changes are critical events in NPC tumorigenesis.

Loss of heterozygosity on the long arm of chromosome 11 in nasopharyngeal carcinoma.

Loss of heterozygosity (LOH) on the long arm of chromosome 11 had been reported in many types of solid tumors. In this study, we investigated the LOH patterns of chromosome 11 on 52 primary nasopharyngeal carcinomas using 10 microsatellite polymorphic markers. The results revealed that 28 of the 52 cases (53.8%) demonstrated LOH on at least one of the nine 11q microsatellite loci studied. The highest frequencies of LOH were found at the two loci D11S2000 (36.1%) and D11S934 (34.5 %), both located at 11q22-24. Two distinct regions of deletion were found at 11q, with the first one defined by INT-2 and D11S900 at 11q13.3-22, and the second region located between D11S2000 and D11S934 at 11q22-24. The two deletion regions overlap with the common areas of deletion reported in other tumor types. This suggests the presence of multiple putative tumor suppressor genes on chromosome 11q that may play a role in the development of nasopharyngeal carcinomas.

Kinetics of plasma Epstein-Barr virus DNA during radiation therapy for nasopharyngeal carcinoma.

We studied the kinetics of circulating EBV DNA in the plasma of nasopharyngeal carcinoma (NPC) patients. Serial weekly sampling of 10 NPC patients revealed a rapid decline in plasma EBV DNA concentration after treatment. In two subjects, an initial rise in the circulating EBV DNA level was observed immediately after treatment initiation. Plasma EBV DNA levels were monitored daily during the first treatment week in a second cohort of five patients, and the results indicated that an initial rise in plasma EBV DNA concentration could be observed in all subjects during the first treatment week. This observation is consistent with the liberation of EBV DNA after therapy-induced cancer cell death. After this initial rise, plasma EBV DNA concentration was found to decay with a median half-life of 3.8 days (interquartile range, 2.4-4.4 days). Kinetic analysis of circulating tumor-derived DNA during treatment may be a powerful tool for evaluating the in vivo response of NPC and other tumors to antineoplastic treatment and may improve our understanding of the biology of plasma nucleic acids.

High frequency of chromosome 3p deletion in histologically normal nasopharyngeal epithelia from southern Chinese.

We have examined the presence of loss of heterozygosity (LOH) on chromosome 3p in histologically normal nasopharyngeal epithelia (NP), dysplastic lesions, and carcinoma of the nasopharynx from different ethnic and geographic regions. Microdissected normal NP from noncancerous individuals and nasopharyngeal carcinoma (NPC) samples from both the high-risk group (southern Chinese in Hong Kong) and two low-risk groups for NPC (central/northern Chinese in Anhui/Beijing and Caucasians in Toronto) were included. All NPC samples showed high incidence of 3p deletion (81-100%). High frequencies of LOH on 3p were also detected in normal NP (73.9%) and dysplastic lesions (75%) from the southern Chinese. Significant lower frequency of LOH on 3p was noted in normal NP from the low-risk groups (20%) than those from high-risk groups (P = 0.0003). The presence of such genetic alterations in the histologically normal NP and dysplastic lesions suggests that it is an early event in tumor development. The higher frequency of 3p LOH found in normal NP from southern Chinese compared with those from low-risk groups may be related to the distinct cancer incidence among these populations.

A region of homozygous deletion on chromosome 9p21-22 in primary nasopharyngeal carcinoma.

Using 21 microsatellite polymorphic markers spanning both p and q arms, we have performed detailed deletion mapping on chromosome 9 in 18 primary nasopharyngeal carcinomas. All 18 tumors were informative at multiple loci. Eleven of the 18 cases (61%) demonstrated allelic deletion of chromosome 9. Among these 11, 6 cases are likely to be tumors with monosomy of chromosome 9. The other 5 cases demonstrated partial deletion by showing multiple areas of allelic loss. In one of the 5 cases, a homozygous deletion region was identified which includes D9S126, D9S171, and IFNA loci at 9p21-22, situated between loci D9S161 (9p21) and D9S162 (9p21-22). The presence of a homozygous deletion strongly suggests the presence of tumor suppressor gene(s) involved in the tumorigenesis of nasopharyngeal carcinoma. The same region has been reported to include some potential tumor suppressor gene loci in other cancers. This is the first reported finding of frequent genetic loss observed on chromosome 9 in nasopharyngeal carcinomas in addition to allelic loss on chromosome 3p at specific regions. Our results suggest that tumorigenesis and progression of nasopharyngeal carcinomas, like other solid tumors, involves multiple genetic changes associated with the inactivation of tumor suppressor genes.