Biomedical subjects

David Sidransky

Publications and source records attributed to David Sidransky.

At least 73 records · Page 4Linked to original sources

PubMed2004

Lactoferrin down-regulates G1 cyclin-dependent kinases during growth arrest of head and neck cancer cells.

The molecular mechanism of lactoferrin-induced cell growth inhibition is incompletely understood. Studying head and neck cancer cells treated with human lactoferrin, we observed growth arrest in three of four cell lines tested. This growth arrest was caused by cell cycle inhibition at the G0-G1 checkpoint. Lactoferrin-induced growth inhibition was associated with a large increase in p27 protein, accompanied by decreased phosphorylation of retinoblastoma protein, and suppression of cyclin E. Decreased levels of phosphorylated Akt were also observed in lactoferrin-sensitive cell lines after treatment. These findings suggest that in head and neck cancer cells the growth inhibitory effects of lactoferrin are mediated through a p27/cyclin E-dependent pathway that may be modulated in part by changes in Akt phosphorylation.

Cell Cycle Proteins↗

PubMed2004

Altered sumoylation of p63alpha contributes to the split-hand/foot malformation phenotype.

p63 mutations have been identified in several developmental abnormalities, including split-hand/foot malformation (SHFM). In this study, we demonstrate that the C-terminal domain of p63alpha associates with the E2 ubiquitin conjugating enzyme, Ubc9. A p63alpha mutation, Q634X, which naturally occurs in SHFM modulated the interaction of p63alpha with Ubc9 in yeast genetic assay. Furthermore, Ubc9 catalyzed the conjugation of p63alpha with small ubiquitin modifier-1 (SUMO-1), which covalently modified p63alpha in vitro and in vivo at two positions (K549E and K637E), each situated in a SUMO-1 modification consensus site (phiKXD/E). In addition, p63alpha mutations (K549E and K637E) abolished sumoylation of p63alpha, dramatically activated transactivation properties of TAp63alpha, and inhibited the dominant-negative effect of DeltaNp63alpha. These p63alpha mutations also affected the transcriptional regulation of gene targets involved in bone and tooth development (e.g., RUNX2 and MINT) and therefore might contribute to the molecular mechanisms underlying the SHFM phenotype.

Amino Acid Sequence↗

PubMed2004

RACK1 and stratifin target DeltaNp63alpha for a proteasome degradation in head and neck squamous cell carcinoma cells upon DNA damage.

p53 family members with a transactivation (TA) domain induce cell cycle arrest and promote apoptosis. However, DeltaNp63 isotypes lacking the TA-domain promote cell proliferation and tumorigenesis in vitro and in vgammavo. Although p53, TAp63 or TAp73 are stabilized upon DNA damage, we found that the genotoxic stress agents induced a dramatic decrease and phosphorylation of DeltaNp63alpha in squamous cell carcinoma cells. Further work revealed that RACK1 physically associated with the p63alpha C-terminal domain through its WD40 domain. However, stratifin binds with phosphorylated DeltaNp63alpha in response to cisplatin. Upon DNA damage induced by cisplatin, stratifin mediated a nuclear export of DeltaNp63alpha into cytoplasm and then RACK1 targeted latter into a proteasome degradation pathway possibly serving as an E3 ubiquitin ligase. Moreover, siRNA knockdown of both stratifin and RACK1 inhibited a nuclear export and protein degradation of DeltaNp63alpha, respectively. Our data suggest that modification and down regulation of DeltaNp63alpha is one of the major determinants of the cellular response to DNA damage in human head and neck cancers.

14-3-3 Proteins↗

PubMed2004

Inverse correlation between cyclin A1 hypermethylation and p53 mutation in head and neck cancer identified by reversal of epigenetic silencing.

Aberrant promoter hypermethylation of tumor suppressor genes is proposed to be a common feature of primary cancer cells. We recently developed a pharmacological unmasking microarray approach to screen unknown tumor suppressor gene candidates epigenetically silenced in human cancers. In this study, we applied this method to identify such genes in head and neck squamous cell carcinoma (HNSCC). We identified 12 novel methylated genes in HNSCC cell lines, including PGP9.5, cyclin A1, G0S2, bone-morphogenetic protein 2A, MT1G, and neuromedin U, which showed frequent promoter hypermethylation in primary HNSCC (60%, 45%, 35%, 25%, 25%, and 20%, respectively). Moreover, we discovered that cyclin A1 methylation was inversely related to p53 mutational status in primary tumors (P = 0.015), and forced expression of cyclin A1 resulted in robust induction of wild-type p53 in HNSCC cell lines. Pharmacological unmasking followed by microarray analysis is a powerful tool to identify key methylated tumor suppressor genes and relevant pathways.

Carcinoma, Squamous Cell↗

PubMed2004

Characterization of a human homologue of proteolysis-inducing factor and its role in cancer cachexia.

Cachexia is an important cause of secondary morbidity and mortality in patients with cancer. Previous studies have suggested that cancer-associated cachexia may be due in part to tumor-specific production and secretion of a glycosylated peptide, proteolysis-inducing factor, originally identified in a murine cancer cachexia model. We report here the cloning of a human cDNA that generates a peptide having high-sequence homology to this proteolysis-inducing factor. Constitutive expression of human proteolysis-inducing factor is low or absent in most normal human tissues but appears to be elevated in some human tumors. Stable forced expression of human proteolysis-inducing factor in multiple murine and human cell lines results in a secreted protein, but no glycosylation of the protein is detected. In addition, tumor xenografts engineered to overexpress human proteolysis-inducing factor protein do not induce cachexia in vivo. These findings raise important questions as to potential cross-species differences in protein sequence and processing of murine proteolysis-inducing factor and human proteolysis-inducing factor, as well as the nature of the relationship between human proteolysis-inducing factor and the development of cancer cachexia.

Amino Acid Sequence↗

PubMed2004

Optimal use of a panel of methylation markers with GSTP1 hypermethylation in the diagnosis of prostate adenocarcinoma.

PURPOSE: In this study, we tested the ability of a panel of hypermethylation markers to improve the sensitivity of histologic prostate cancer detection in sextant needle biopsies. EXPERIMENTAL DESIGN: We obtained fresh-frozen sextant biopsies from 72 excised prostates and directly compared blinded histologic review and quantitative real-time methylation-specific PCR for hypermethylation of four genes, Tazarotene-induced gene 1 (TIG1), adenomatous polyposis coli (APC), retinoic acid receptor beta2 (RARbeta2), and glutathione S-transferase pi (GSTP1) to detect the presence of prostate cancer. Results were compared with the final surgical pathological review of the resected prostates as the gold standard. RESULTS: Histologic review alone detected carcinoma with a sensitivity of 64% (39 of 61 cases) and 100% specificity. Quantitative real-time methylation-specific PCR for TIG1, APC, RARbeta2, and GSTP1 detected carcinoma with a sensitivity of 70%, 79%, 89%, and 75%, respectively, with 100% specificity for all of the genes. Using this panel of methylation markers in combination with histology resulted in the detection of 59 of 61 (97%) cases of prostate with 100% specificity, a 33% improvement over histology alone. CONCLUSION: The use of a panel of methylation markers as an adjunct to histologic review may substantially augment prostate cancer diagnosis from needle biopsies.

Acyltransferases↗

PubMed2004

Microsatellite analysis of serum DNA in patients with head and neck cancer.

We have shown previously that microsatellite alterations in serum DNA was predictive of distant metastasis in a study with 21 primary head and neck squamous cell carcinoma patients. To further investigate serum microsatellite alterations as a prognostic tool, we carried out microsatellite analysis of serum DNA with 10 markers on 152 patients with head and neck cancer. Forty-five percent (68/152) of patients had microsatellite alterations of serum DNA identical to corresponding tumor DNA. In 16 patients that had distant metastasis, 11 patients had a positive serum test (microsatellite alterations detectable in their serum DNA with one or more markers). The difference in distant metastasis rates between the negative and positive serum tests (6.0% [5/84] vs. 16.2% [11/68], RR = 2.7) was clinically significant and almost reached statistical significance (p = 0.06). When the analysis was restricted to patients with recurrent disease, a positive serum test correlated with those who developed distant metastasis (p = 0.04). Other parameters, such as development of recurrence, stage of the cancer, disease-free survival and overall survival, were not associated with a positive serum test. Detecting tumor DNA in serum by microsatellite analysis may help identify patients at risk for distant metastasis. Therefore, circulating tumor cells may contribute to the presence of tumor DNA in the serum. In the future if a serum test is positive, therapeutic approaches may by intensified, such as platinum-based chemoradiation, to reduce distant failures.

Carcinoma, Squamous Cell↗

PubMed2004

Quantitative detection of promoter hypermethylation of multiple genes in the tumor, urine, and serum DNA of patients with renal cancer.

Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of human cancers and is a promising marker for cancer detection. We investigated the feasibility of detecting aberrant DNA methylation in the urine and serum samples of renal cancer patients. We examined the tumor and the matched urine and serum DNA for aberrant methylation of nine gene promoters (CDH1, APC, MGMT, RASSF1A, GSTP1, p16, RAR-beta2, and ARF) from 17 patients with primary kidney cancer by quantitative fluorogenic real-time PCR. An additional 9 urine samples (total, 26) and 1 serum sample (total, 18) also were tested from renal cancer patients. Urine from 91 patients without genitourinary cancer and serum from 30 age-matched noncancer individuals were used as controls. Promoter hypermethylation of at least two of the genes studied was detected in 16 (94%) of 17 primary tumors. Aberrant methylation in urine and serum DNA generally was accompanied by methylation in the matched tumor samples. Urine samples from 91 control subjects without evidence of genitourinary cancer revealed no methylation of the MGMT, GSTP1, p16, and ARF genes, whereas methylation of RAR-beta2, RASSF1A, CDH1, APC, and TIMP3 was detected at low levels in a few control subjects. Overall, 23 (88%) of 26 urine samples and 12 (67%) of 18 serum samples from cancer patients were methylation positive for at least one of the genes tested. By combination of urine or serum analysis of renal cancer patients, hypermethylation was detected in 16 of 17 patients (94% sensitivity) with high specificity. Our findings suggest that promoter hypermethylation in urine or serum can be detected in the majority of renal cancer patients. This noninvasive high-throughput approach needs to be evaluated in large studies to assess its value in the early detection and surveillance of renal cancer.

Adult↗

PubMed2004

Quantitative RARbeta2 hypermethylation: a promising prostate cancer marker.

Retinoic acid receptor beta2 (RARbeta2) is a tumor suppressor gene frequently hypermethylated in several human neoplasms. To further characterize this epigenetic alteration in prostate cancer progression, we examined tumor tissue from 118 patients with prostate carcinoma (PCa), 38 paired high-grade prostatic intraepithelial neoplasias (HGPIN), and non-neoplastic prostate tissue from 30 patients with benign prostate hyperplasia (BPH), using quantitative methylation-specific PCR. We found RARbeta2 hypermethylation in 97.5% of PCa, 94.7% of HGPIN, and 23.3% of BPH. Methylation levels were significantly higher in PCa compared with HGPIN and BPH (P < 0.00001). By establishing an empiric cutoff value, we were able to discriminate between neoplastic and non-neoplastic tissue, with 94.9% sensitivity and 100% specificity. Moreover, RARbeta2 methylation levels correlated with higher pathological stage (r = 0.30, P = 0.0009). This quantitative assay represents a novel and promising molecular marker that may augment current approaches for prostate cancer detection.

Adult↗

PubMed2004

Gene expression alterations over large chromosomal regions in cancers include multiple genes unrelated to malignant progression.

In solid tumors, the relationship between DNA copy number and global expression over large chromosomal regions has not been systematically explored. We used a 12,626-gene expression array analysis of head and neck squamous cell carcinoma and normal oral mucosa and annotated gene expression levels to specific chromosomal loci. Expression alterations correlated with reported data using comparative genomic hybridization. When genes with significant differences in expression between normal and malignant lesions, as defined by significance analysis of microarrays (SAM), were compared to nonsignificant genes, similar chromosomal patterns of alteration in expression were noted. Individual tumors underwent microsatellite analysis and chi(2) analysis of expression at 3p and 22q. Significant 3p underexpression and 22q overexpression were found in all primary tumors with 3p and 22q allelic imbalance, respectively, whereas no tumor without allelic imbalance on these chromosomal arms demonstrated expression differences. Loss and gain of chromosomal material in solid cancers can alter gene expression over large chromosomal regions, including multiple genes unrelated to malignant progression.

Allelic Imbalance↗

PubMed2004

Exon 15 BRAF mutations are uncommon in melanomas arising in nonsun-exposed sites.

PURPOSE: An activating point mutation of the BRAF oncogene has been identified in a high proportion of cutaneous nevi and cutaneous melanomas, but its frequency in melanomas arising from the mucosa of head and neck is unknown. EXPERIMENTAL DESIGN: We tested 17 malignant mucosal melanomas of the head and neck for the thymine (T)-->adenine (A) missense mutation at nucleotide 1796 in the BRAF gene using direct sequencing and a newly developed assay that uses a novel primer extension method (Mutector assay). We also tested 21 cutaneous melanomas, including 13 arising from sun-exposed sites and 8 from a nonsun-exposed site, the vulvar skin. RESULTS: The 1796T-->A mutation was detected in only 1 (6%) of the sinonasal melanomas. As for cutaneous melanomas, a BRAF mutation was detected in 8 (62%) of the tumors arising in sun-exposed sites but in none (0%) of vulvar melanomas. CONCLUSIONS: In contrast to cutaneous melanomas arising in sun-exposed sites, mucosal melanomas of the head and neck do not frequently harbor an activating mutation of BRAF. This finding additionally supports the view that the various subtypes of melanoma are not equivalent and that distinct genetic alterations may underlie well recognized differences in risk factors and behavioral patterns. Accordingly, patients with melanomas should not be collectively regarded as a uniform group as new strategies are developed that target specific genetic alterations.

Adenine↗

PubMed2004

Mutational analysis of BRAF in fine needle aspiration biopsies of the thyroid: a potential application for the preoperative assessment of thyroid nodules.

BACKGROUND: Fine needle aspiration (FNA) is routinely used in the preoperative evaluation of thyroid nodules, but subsequent patient management is often complicated by the inability to decisively recognize malignancy on cytologic grounds alone. Activating mutations of the BRAF oncogene commonly occur in papillary thyroid carcinomas (PTCs) but not in other types of benign and malignant thyroid lesions. Mutational analysis of FNAs could enhance selection of thyroid nodules for surgical removal. METHODS: Ninety-five excised PTCs along with 49 corresponding FNAs were evaluated for BRAF mutations by a newly developed assay that uses a novel primer extension method (MutectorR assay) and by direct sequencing. An additional 42 FNAs from thyroid nodules that were excised based on a suspicion of malignancy were also evaluated. RESULTS: BRAF mutations were identified in 36 of the 95 (38%) excised PTCs. By histological subtype, BRAF mutations were more common in conventional PTCs than in the follicular variant (67% versus 12%; P < 0.0001; chi(2)). Analysis of the preoperative FNAs accurately reflected BRAF status of the resected PTC in 46 of the 49 paired samples (94% concordance). In FNA samples grouped according to the preoperative cytologic findings (malignant, n = 25; benign, n = 11; and indeterminate, n = 55), a BRAF mutation confirmed the diagnosis of PTC in 72% of carcinomas within the malignant group, and it established the diagnosis of PTC in 16% of carcinomas within the indeterminate group. BRAF mutations were not detected in FNAs from 32 benign thyroid lesions. Direct sequencing and the MutectorR assay yielded completely concordant results. CONCLUSIONS: BRAF mutations are common in conventional PTCs, and they are specific for PTC. A BRAF mutation can be reliably detected in cells aspirated from a thyroid nodule suggesting a role for this marker in the preoperative evaluation of thyroid nodules.

Biopsy, Fine-Needle↗

PubMed2004

Real-time gap ligase chain reaction: a rapid semiquantitative assay for detecting p53 mutation at low levels in surgical margins and lymph nodes from resected lung and head and neck tumors.

PURPOSE: We have developed a real-time semiquantitative gap ligase chain reaction for detecting p53 point mutations at low level in a background of excess of wild-type DNA. EXPERIMENTAL DESIGN: This method was validated by direct comparison to a previously validated but cumbersome phage plaque hybridization assay. Forty-one surgical margins and lymph nodes from 10 cases of head and neck squamous cell carcinoma and lung carcinoma were tested for p53 mutant clones. RESULTS: Both methods detected p53 mutants in margins from 8 of the 10 cases, whereas standard pathology detected cancer cells in only 3 cases. Positive margins included tissue samples with a tumor/normal DNA ratio of up to 1:1000. CONCLUSIONS: This novel molecular approach can be performed in <5 h facilitating intraoperative use for real-time surgical resection.

Carcinoma, Squamous Cell↗

PubMed2004

Detection of promoter hypermethylation of multiple genes in the tumor and bronchoalveolar lavage of patients with lung cancer.

PURPOSE: Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of lung cancers and is a promising marker for cancer detection. We investigated the feasibility of detecting aberrant DNA methylation in the bronchoalveolar lavage (BAL) samples of lung cancer patients. EXPERIMENTAL DESIGN: We examined the tumor and the matched BAL DNA for aberrant methylation of eight gene promoters (CDH1, APC, MGMT, RASSF1A, GSTP1, p16, RAR-beta 2, and ARF) from 31 patients with primary lung tumors by quantitative fluorogenic real-time PCR. BAL from 10 age-matched noncancer patients was used as a control. RESULTS: Promoter hypermethylation of at least one of the genes studied was detected in all 31 lung primary tumors; 27 (87%) CDH1, 17 (55%) APC, 14 (45%) RASSF1A, 12 (39%) MGMT, 7 (23%) p16, 3 (10%) GSTP1, 3 (10%) RAR-beta 2, and 0 (0%) ARF. Methylation was detected in CDH1 (48%), APC (29%), RASSF1A (29%), MGMT (58%), p16 (14%), GSTP1 (33%), RAR-beta 2 (0%), and ARF (0%) of BAL samples from matched methylation-positive primary tumors, and in every case, aberrant methylation in BAL DNA was accompanied by methylation in the matched tumor samples. BAL samples from 10 controls without evidence of cancer revealed no methylation of the MGMT, GSTP1, p16, ARF, or RAR-beta 2 genes whereas methylation of RASSF1, CDH1, and APC was detected at low levels. Overall, 21 (68%) of 31 BAL samples from cancer patients were positive for aberrant methylation. CONCLUSION: Our findings suggest that promoter hypermethylation in BAL can be detected in the majority of lung cancer patients. This approach needs to be evaluated in large early detection and surveillance studies of lung cancer.

Bronchoalveolar Lavage↗

PubMed2004

CDC91L1 (PIG-U) is a newly discovered oncogene in human bladder cancer.

Genomic amplification at 20q11-13 is a common event in human cancers. We isolated a germline translocation breakpoint at 20q11 from a bladder cancer patient. We identified CDC91L1, the gene encoding CDC91L1 (also called phosphatidylinositol glycan class U (PIG-U), a transamidase complex unit in the glycosylphosphatidylinositol (GPI) anchoring pathway), as the only gene whose expression was affected by the translocation. CDC91L1 was amplified and overexpressed in about one-third of bladder cancer cell lines and primary tumors, as well as in oncogenic uroepithelial cells transformed with human papillomavirus (HPV) E7. Forced overexpression of CDC91L1 malignantly transformed NIH3T3 cells in vitro and in vivo. Overexpression of CDC91L1 also resulted in upregulation of the urokinase receptor (uPAR), a GPI-anchored protein, and in turn increased STAT-3 phosphorylation in bladder cancer cells. Our findings suggest that CDC91L1 is an oncogene in bladder cancer, and implicate the GPI anchoring system as a potential oncogenic pathway and therapeutic target in human cancers.

Animals↗

PubMed2004

Early occurrence of RASSF1A hypermethylation and its mutual exclusion with BRAF mutation in thyroid tumorigenesis.

Follicular epithelial cell-derived thyroid tumors are common neoplasms comprised mainly of benign thyroid adenomas, follicular thyroid cancers, and papillary thyroid cancers (PTCs). Hypermethylation of the tumor suppressor gene RASSF1A and activating mutation of BRAF gene have been reported recently in thyroid cancers. To additionally investigate the roles of these two epigenetic/genetic alterations in thyroid tumor progression, we examined their occurrences and relationship in both benign and malignant thyroid neoplasms. With real-time quantitative methylation-specific PCR, we found that 4 of 9 (44%) benign adenomas, 9 of 12 (75%) follicular thyroid cancers tumors, and 6 of 30 (20%) of PTC tumors harbored promoter methylation in > or = 25% of RASSF1A alleles. Additional quantitative analysis revealed RASSF1A methylation only in BRAF mutation-negative PTCs. A similar inverse correlation of RASSF1A methylation with BRAF mutation was seen in thyroid tumor cell lines. Our results, therefore, suggest that epigenetic inactivation of RASSF1A through aberrant methylation is an early step in thyroid tumorigenesis. Like the previously reported mutually exclusive relationship between BRAF mutation and other Ras pathway components such as RET/PTC rearrangement, a mutually exclusive relationship also exists between BRAF mutation and RASSF1A methylation in thyroid tumorigenesis.

Cell Line, Tumor↗

PubMed2004

Intraoperative molecular margin analysis in head and neck cancer.

BACKGROUND: Tumor-specific molecular alterations in surgical margins have been shown to predict risk of local recurrence. However, assays used for these analyses are time-consuming and therefore cannot be used in the intraoperative setting. OBJECTIVE: To detect and quantify tumor-specific methylated promoter sequences in surgical margins in a time frame suitable for intraoperative use. DESIGN: A novel quantitative methylation-specific polymerase chain reaction (QMSP) protocol. METHODS: A total of 13 patients with head and neck squamous cell carcinoma (HNSCC) were initially characterized for molecular alterations in their tumor at the time of biopsy. Six primary tumors were found to harbor promoter hypermethylation for p16 and O6-methylguanine-DNA-methyltransferase (MGMT) genes. Rapid QMSP was then used to identify promoter hypermethylation of these genes in the surgical margins. Results were compared with standard intraoperative histologic frozen section analysis and with conventional QMSP. RESULTS: Using our rapid QMSP assay, we found that 3 patients had methylation-positive margins. Tumor margins from 2 patients were methylated for p16 alone, and margins from 1 patient were methylated for p16 and MGMT simultaneously. Molecular margin analysis was completed in less than 5 hours, a time frame appropriate for selected major HNSCC resections that require combined primary tumor resection, cervical lymphadenectomy, and complex reconstruction. This technique was comparable in sensitivity to conventional QMSP. CONCLUSION: Rapid molecular margin analysis using QMSP is feasible and may be performed intraoperatively in selected patients with HNSCC that requires extensive resection.

Carcinoma, Squamous Cell↗

PubMed2004

Aquaporin expression in human lymphocytes and dendritic cells.

Aquaporins (AQPs) are molecular water channels, and 10 related AQPs have been identified in mammals. So far, the study of mammalian AQP expression has been limited mainly to mice and rat lung, kidney, brain, and gastrointestinal tract. Although AQP3 and AQP7 have been shown to be involved in volume-regulating mechanisms in dendritic cells, the exact patterns of AQP expression in the human immune system are not well understood. Using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of peripheral blood from healthy donors, we demonstrated the expression of AQP1, AQP3, and AQP5 in activated B and T lymphocytes and the expression of AQP3 and AQP5 in immature dendritic cells. None of the tested AQPs was expressed in inactivated B or T lymphocytes. In situ hybridization studies using human tonsils showed that AQP1, AQP3, and AQP5 were expressed almost exclusively in the germinal centers. Further in situ hybridization showed that expression of AQP1, AQP3, and AQP5 were detected in tumor-infiltrating lymphocytes surrounding bronchogenic carcinoma of the lung and that expression of AQP3 and AQP5 was detected in dendritic cells. These findings provide new insights into the expression patterns of AQPs in the human immune system. While the exact role of AQPs in the human immune system remains to be determined, we propose that AQP expression patterns may be used as a marker to study lymphocyte activation and proliferation.

Aquaporins↗