Biomedical subjects

D M Shin

Publications and source records attributed to D M Shin.

At least 19 recordsLinked to original sources

PubMed2007

TRPC channels: interacting proteins.

TRP channels, in particular the TRPC and TRPV subfamilies, have emerged as important constituents of the receptor-activated Ca2+ influx mechanism triggered by hormones, growth factors, and neurotransmitters through activation ofphospholipase C (PLC). Several TRPC channels are also activated by passive depletion of endoplasmic reticulum (ER) Ca2+. Although in several studies the native TRP channels faithfully reproduce the respective recombinant channels, more often the properties of Ca2+ entry and/or the store-operated current are strikingly different from that of the TRP channels expressed in the same cells. The present review aims to discuss this disparity in the context of interaction of TRPC channels with auxiliary proteins that may alter the permeation and regulation of TRPC channels.

Animals↗

PubMed2002

Staurosporine mobilizes Ca(2+) from secretory granules by inhibiting protein kinase C in rat submandibular acinar cells.

Staurosporine was previously shown to mobilize Ca(2+) from the thapsigargin-insensitive Ca(2+) store in rat submandibular acinar cells. However, the nature of the store is not yet known. Therefore, in the present study, the staurosporine-releasable intracellular Ca(2+) store was characterized. Staurosporine increased the cytosolic Ca(2+) concentration ([Ca(2+)](c)) after the inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) store was depleted. Ionomycin caused only small increases in [Ca(2+)](c) after the depletion of the IP(3)-sensitive Ca(2+) store, whereas ionomycin+monensin caused large increases. However, ionomycin+monensin did not increase [Ca(2+)](c) when added after [Ca(2+)](c) was increased by staurosporine, indicating that the acidic Ca(2+) store was the main source of Ca(2+). The acidic Ca(2+) store appeared to be associated with secretory granules, since ionomycin+monensin- and staurosporine-induced [Ca(2+)](c) increases were significantly reduced when the acinar cells were degranulated. The effect of staurosporine on [Ca(2+)](c) was mimicked by other protein kinase C inhibitors. Therefore, we conclude that staurosporine mobilizes Ca(2+) from secretory granules, probably through the inhibition of protein kinase C in rat submandibular acinar cells.

Animals↗

PubMed2001

Regulation of Ca2+-release-activated Ca2+ current (Icrac) by ryanodine receptors in inositol 1,4,5-trisphosphate-receptor-deficient DT40 cells.

Persistence of capacitative Ca(2+) influx in inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R)-deficient DT40 cells (DT40(IP(3)R-/-)) raises the question of whether gating of Ca(2+)-release activated Ca(2+) current (I(crac)) by conformational coupling to Ca(2+)-release channels is a general mechanism of gating of these channels. In the present work we examined the properties and mechanism of activation of I(crac) Ca(2+) current in wild-type and DT40(IP(3)R-/-) cells. In both cell types passive depletion of internal Ca(2+) stores by infusion of EGTA activated a Ca(2+) current with similar characteristics and time course. The current was highly Ca(2+)-selective and showed strong inward rectification, all typical of I(crac). The activator of ryanodine receptor (RyR), cADP-ribose (cADPR), facilitated activation of I(crac), and the inhibitors of the RyRs, 8-N-cADPR, ryanodine and Ruthenium Red, all inhibited I(crac) activation in DT40(IP(3)R-/-) cells, even after complete depletion of intracellular Ca(2+) stores by ionomycin. Wild-type and DT40(IP(3)R-/-) cells express RyR isoforms 1 and 3. RyR levels were adapted in DT40(IP(3)R-/-) cells to a lower RyR3/RyR1 ratio than in wild-type cells. These results suggest that IP(3)Rs and RyRs can efficiently gate I(crac) in DT40 cells and explain the persistence of I(crac) gating by internal stores in the absence of IP(3)Rs.

Blotting, Western↗

PubMed2001

Phase II study of the antiangiogenesis agent thalidomide in recurrent or metastatic squamous cell carcinoma of the head and neck.

BACKGROUND: Thalidomide has been shown to have antiangiogenic effects in preclinical models as well as a significant antitumor effect in hematologic tumors such as multiple myeloma. The authors performed this Phase II study to determine the activity, toxicity profile, and antiangiogenic effect of thalidomide in patients with locoregionally recurrent or metastatic squamous cell carcinoma of the head and neck. METHODS: Twenty-one patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with single-agent thalidomide. All patients had received radiation therapy, and most had undergone surgery (95%) and/or chemotherapy (90%). Thalidomide was initiated at 200 mg;3>daily and increased to a target dose of 1000 mg daily. Patients continued treatment until disease progression, unacceptable toxicity, or death occurred. RESULTS: All 21 patients eventually developed progressive disease. Median time to progression was 50 days (95% confidence interval, 28-70), with median overall survival time of 194 days (95% lower confidence boundary, 151), similar to the progression and survival times reported for this patient group with other agents. Thalidomide was generally well tolerated, with few patients experiencing Grades 3 to 4 toxicities. Serum vascular endothelial growth factor and basic fibroblast growth factor levels increased in six of seven patients, for whom paired serum samples were available and all of whom had progressive disease. CONCLUSIONS: In this heavily pretreated population of patients with advanced squamous cell carcinoma of the head and neck, thalidomide does not appear to have single-agent antitumor activity. Further evaluation of the mechanism of action of thalidomide is indicated. Potentially, future evaluations of thalidomide may be performed in combination with other antiangiogenic or cytotoxic agents in patients with earlier stage disease or in patients with minimal residual disease.

Administration, Oral↗

PubMed2001

Polarized expression of G protein-coupled receptors and an all-or-none discharge of Ca2+ pools at initiation sites of [Ca2+]i waves in polarized exocrine cells.

In the present work we examined localization and behavior of G protein-coupled receptors (GPCR) in polarized exocrine cells to address the questions of how luminal to basal Ca(2+) waves can be generated in a receptor-specific manner and whether quantal Ca(2+) release reflects partial release from a continuous pool or an all-or-none release from a compartmentalized pool. Immunolocalization revealed that expression of GPCRs in polarized cells is not uniform, with high levels of GPCR expression at or near the tight junctions. Measurement of phospholipase Cbeta activity and receptor-dependent recruitment and trapping of the box domain of RGS4 in GPCRs complexes indicated autonomous functioning of G(q)-coupled receptors in acinar cells. These findings explain the generation of receptor-specific Ca(2+) waves and why the waves are always initiated at the apical pole. The initiation site of Ca(2+) wave at the apical pole and the pattern of wave propagation were independent of inositol 1,4,5-trisphosphate concentration. Furthermore, a second Ca(2+) wave with the same initiation site and pattern was launched by inhibition of sarco/endoplasmic reticulum Ca(2+)-ATPase pumps of cells continuously stimulated with sub-maximal agonist concentration. By contrast, rapid sequential application of sub-maximal and maximal agonist concentrations to the same cell triggered Ca(2+) waves with different initiation sites. These findings indicate that signaling specificity in pancreatic acinar cells is aided by polarized expression and autonomous functioning of GPCRs and that quantal Ca(2+) release is not due to a partial Ca(2+) release from a continuous pool, but rather, it is due to an all-or-none Ca(2+) release from a compartmentalized Ca(2+) pool.

Animals↗

PubMed2001

Combined interferon-alfa, 13-cis-retinoic acid, and alpha-tocopherol in locally advanced head and neck squamous cell carcinoma: novel bioadjuvant phase II trial.

PURPOSE: Retinoids and interferons (IFNs) have single-agent and synergistic combined effects in modulating cell proliferation, differentiation, and apoptosis in vitro and clinical activity in vivo in the head and neck and other sites. Alpha-tocopherol has chemopreventive activity in the head and neck and may decrease 13-cis-retinoic acid (13-cRA) toxicity. We designed the present phase II adjuvant trial to prevent recurrence or second primary tumors (SPTs) using 13-cRA, IFN-alpha, and alpha-tocopherol in locally advanced-stage head and neck cancer. PATIENTS AND METHODS: After definitive local treatment with surgery, radiotherapy, or both, patients with locally advanced SCCHN were treated with 13-cRA (50 mg/m(2)/d, orally, daily), IFN-alpha (3 x 10(6) IU/m(2), subcutaneous injection, three times a week), and alpha-tocopherol (1,200 IU/d, orally, daily) for 12 months, with a dose modification. Screening for recurrence or SPTs was performed every 3 months. RESULTS: Tumors of 11 (24%) of the 45 treated patients were stage III, and 34 (76%) were stage IV. Thirty-eight (86%) of 44 patients completed the full 12-month treatment (doses modified as needed). Toxicity generally was consistent with previous IFN and 13-cRA reports and included mild to moderate mucocutaneous and flu-like symptoms; occasional significant fatigue (grade 3 in 7% of patients), mild to moderate hypertriglyceridemia in 30% of patients who continued treatment along with antilipid therapy, and mild hematologic side effects. Six patients did not complete the planned treatment because of intolerable toxicity or social problems. At a median 24-months of follow-up, our clinical end point rates were 9% for local/regional recurrence (four patients), 5% for local/regional recurrence and distant metastases (two patients), and 2% for SPT (one patient), which was acute promyelocytic leukemia (ie, not of the upper aerodigestive tract). Median 1- and 2-year rates of overall survival were 98% and 91%, respectively, and of disease-free survival were 91% and 84%, respectively. CONCLUSION: The novel biologic agent combination of IFN-alpha, 13-cRA, and alpha-tocopherol was generally well tolerated and promising as adjuvant therapy for locally advanced squamous cell carcinoma of the head and neck. We are currently conducting a phase III randomized study of this combination (v no treatment) to confirm these phase II study results.

Adult↗

PubMed2001

Plasticity and adaptation of Ca2+ signaling and Ca2+-dependent exocytosis in SERCA2(+/-) mice.

Darier's disease (DD) is a high penetrance, autosomal dominant mutation in the ATP2A2 gene, which encodes the SERCA2 Ca2+ pump. Here we have used a mouse model of DD, a SERCA2(+/-) mouse, to define the adaptation of Ca2+ signaling and Ca2+-dependent exocytosis to a deletion of one copy of the SERCA2 gene. The [Ca2+]i transient evoked by maximal agonist stimulation was shorter in cells from SERCA2(+/-) mice, due to an up-regulation of specific plasma membrane Ca2+ pump isoforms. The change in cellular Ca2+ handling caused approximately 50% reduction in [Ca2+]i oscillation frequency. Nonetheless, agonist-stimulated exocytosis was identical in cells from wild-type and SERCA2(+/-) mice. This was due to adaptation in the levels of the Ca2+ sensors for exocytosis synaptotagmins I and III in cells from SERCA2(+/-) mice. Accordingly, exocytosis was approximately 10-fold more sensitive to Ca2+ in cells from SERCA2(+/-) mice. These findings reveal a remarkable plasticity and adaptability of Ca2+ signaling and Ca2+-dependent cellular functions in vivo, and can explain the normal function of most physiological systems in DD patients.

Animals↗

PubMed2001

Multi-institutional phase I/II trial of oral bexarotene in combination with cisplatin and vinorelbine in previously untreated patients with advanced non-small-cell lung cancer.

PURPOSE: Bexarotene (Targretin; Ligand Pharmaceuticals, Inc, San Diego, CA) is a retinoid-X-receptor (RXR)-selective retinoid with preclinical antitumor activity in squamous cell cancers. In this phase I/II trial, we combined bexarotene with cisplatin and vinorelbine in the treatment of patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Forty-three patients who had stage IIIB NSCLC with pleural effusion or stage IV NSCLC and had received no prior therapy received bexarotene in combination with cisplatin (100 mg/m2) and vinorelbine (alternating doses of 30 mg/m2 and 15 mg/m2). In the phase I portion, the daily dose of bexarotene was escalated in cohorts of three patients from 150 mg/m2 to 600 mg/m2, beginning 1 week before the start of the cisplatin-vinorelbine regimen. Once the maximum-tolerated dose (MTD) of bexarotene was determined, the study entered the phase II portion. Response rate was the primary end point; median survival time and 1-year survival rate were secondary end points. RESULTS: In the phase I portion, the daily MTD of bexarotene was determined to be 400 mg/m2. Eight of 43 patients exhibited major responses. Seven (25%) of the 28 patients in the phase II portion responded to treatment. The median survival time in the phase II portion was 14 months; nine (32%) of the 28 patients were still alive at a minimum follow-up of 2 years. One-year and projected 3-year survival rates were 61% and 30%, respectively. The most common grade 3 and 4 adverse events were hyperlipemia, leukopenia, nausea, vomiting, pneumonia, dyspnea, anemia, and asthenia. Grade 3 and 4 laboratory abnormalities with incidences greater than 5% were decreased hemoglobin levels and WBC, absolute neutrophil, and absolute lymphocyte counts and increased prothrombin time and creatinine and amylase levels. Of the two cases of pancreatitis, one required hospitalization and both were associated with increased triglyceride levels. There was one death secondary to renal insufficiency unrelated to bexarotene treatment. CONCLUSION: In patients with advanced NSCLC, bexarotene with cisplatin and vinorelbine yielded acceptable phase II response rates (25%) and was associated with better-than-expected survival (14-month median survival time; 61% 1-year, 32% 2-year, and 30% projected 3-year survival rates). The regimen should be studied in larger clinical trials.

Administration, Oral↗

PubMed2001

Phase II study of paclitaxel, ifosfamide, and carboplatin in patients with recurrent or metastatic head and neck squamous cell carcinoma.

BACKGROUND: In the current study the authors assessed the antitumor activity (including response rate, duration of response, and survival) and toxicity profile (including anorexia, fatigue, emesis, and peripheral neuropathy) of a combination of paclitaxel, ifosfamide, and carboplatin (TIC) in patients with recurrent or metastatic squamous cell carcinoma of the head and neck (SCCHN). The trial hypothesis was that the TIC therapeutic index would be as high as that of paclitaxel, ifosfamide, and cisplatin (TIP) in this setting, but with less toxicity. METHODS: Patients with recurrent or metastatic SCCHN were treated with 175 mg/m(2) of paclitaxel as a 3-hour infusion on Day 1, 1000 mg/m(2) of ifosfamide as a 2-hour infusion on Days 1-3, 600 mg/m(2) of mesna on Days 1-3, and carboplatin (area under the concentration-time curve of 6) as a 30-minute infusion on Day 1; the regimen was repeated every 3-4 weeks. All patients were premedicated with dexamethasone, diphenhydramine, and cimetidine before paclitaxel infusion. Prophylactic hematopoietic growth factors were not given. RESULTS: Among 56 patients entered onto the study, 55 patients were analyzed for survival rates (locoregional recurrence alone in 56% of patients and distant metastasis with or without locoregional recurrence in 44% of patients). Fifty-four patients were evaluable for tumor response and toxicity. A total of 32 patients (59%) had disease that responded to treatment; the complete response rate was 17% (9 of 54 patients). The median duration of the responses was 3.7 months (95% confidence interval [95% CI], 3.4-7.8 months) and that of complete responses was 9.7 months (95% CI, 7.4 months to date of last follow-up). The median duration of follow-up care in all patients was 13.5 months. The median survival time for all patients was 9.1 months (95% CI, 7.9-12.2 months). The regimen was well tolerated. Neutropenic fever developed in 30% of the patients; 1 patient died of neutropenia and sepsis. Other toxic effects included Grade 2-3 anorexia in 13% of patients, Grade 2-3 weight loss in 11% of patients, Grade 2-3 fatigue in 27% of patients, Grade 2-3 nausea/emesis in 13% of patients, and Grade 2-3 peripheral neuropathy in 9% of patients (toxicity grading based on the National Cancer Institute's Common Toxicity Criteria). Red blood cell and platelet transfusions were required in 13% and 7% of patients, respectively. CONCLUSIONS: The TIC regimen had high antitumor activity in patients with recurrent or metastatic SCCHN, with a 59% major response rate (17% complete response rate with relatively durable complete responses). Neutropenic fever developed in 30% of the patients, the incidence of which might have been decreased by prophylactic antibiotics or hematopoietic growth factor support. Other toxic effects included significantly lower rates and less severe instances of anorexia, emesis, fatigue, and peripheral neuropathy than those reported with the previously studied TIP regimen. The TIC regimen currently is being studied as an induction chemotherapy regimen in previously untreated patients with locally advanced SCCHN. The activity of TIC (a novel paclitaxel and ifosfamide-based regimen) in patients with recurrent or metastatic SCCHN should be confirmed in a Phase III randomized trial.

Adult↗

PubMed2001

Phase I trial of oral green tea extract in adult patients with solid tumors.

PURPOSE: This trial was designed to determine the maximum-tolerated dose, toxicity, and pharmacology of oral green tea extract (GTE) once daily or three times daily. PATIENTS AND METHODS: Cohorts of three or more adult cancer patients were administered oral GTE with water after meals one or three times daily for 4 weeks, to a maximum of 6 months, depending on disease response and patient tolerance. Pharmacokinetic analyses were encouraged but optional. RESULTS: Dose levels of 0.5 to 5.05 g/m(2) qd and 1.0 to 2.2 g/m(2) tid were explored. A total of 49 patients were studied. PATIENT CHARACTERISTICS: median age, 57 years (range, 27 to 77 years); 23 patients were women (47%); 98% had a Zubrod PS of 1%; 98% had PS of 1; and 21 had non-small-cell lung, 19 had head & neck cancer, three had mesothelioma, and six had other. Mild to moderate toxicities were seen at most dose levels and promptly reversed on discontinuation of GTE. Dose-limiting toxicities were caffeine related and included neurologic and gastrointestinal effects. The maximum-tolerated dose was 4.2 g/m(2) once daily or 1.0 g/m(2) three times daily. No major responses occurred; 10 patients with stable disease completed 6 months of GTE. Pharmacokinetic analyses found accumulation of caffeine levels that were dose dependent, whereas epigallocatechin gallate levels did not accumulate nor appear dose related. CONCLUSION: A dose of 1.0 g/m(2) tid (equivalent to 7 to 8 Japanese cups [120 mL] of green tea three times daily) is recommended for future studies. The side effects of this preparation of GTE were caffeine related. Oral GTE at the doses studied can be taken safely for at least 6 months.

Administration, Oral↗

PubMed2001

Multicenter phase I-II trial of docetaxel, cisplatin, and fluorouracil induction chemotherapy for patients with locally advanced squamous cell cancer of the head and neck.

PURPOSE: We conducted a phase I-II, multi-institutional trial to determine the maximum-tolerated dose (MTD) of cisplatin in an induction chemotherapy regimen of docetaxel, cisplatin, and fluorouracil for squamous cell cancer of the head and neck (SCCHN) and to determine the safety, tolerability, and efficacy of the regimen at MTD. PATIENTS AND METHODS: A total of 43 patients with previously untreated, locally advanced, curable SCCHN were entered. Overall, 29 patients (67%) had N2 or N3 nodal disease and nine (21%) had T4 primary tumors. All patients received docetaxel 75 mg/m(2) on day 1; cisplatin at 75 (level I) or 100 (level II) mg/m(2) on day 1; and a continuous fluorouracil infusion at 1,000 mg/m(2)/d on days 1 through 4. Patients were treated with prophylactic antibiotics on days 5 through 15. Cycles were repeated every 21 days for a total of three cycles. Patients then received definitive therapy based on institutional preferences. RESULTS: Thirteen patients were treated at level I, and 30 patients were treated at level II. All 43 patients were assessable for toxicity. There were no major differences in toxicity between level I and level II. Cisplatin-associated grade 3 or 4 hypomagnesemia or hypocalcemia occurred in 13 (30%) and hearing loss in two patients (5%). Grade 3 or 4 neutropenia was observed in 41 patients (95%) and febrile neutropenia occurred in eight (19%). There was one serious infection (2%). There were 17 (40% [95% confidence interval [CI], 25% to 56%]) clinical complete responders (CR), 23 (54% [95% CI, 39% to 69%]) partial responders (PR), one (2%) with no change, and two (5%) unassessable patients. Major responses (CR, PR) were observed in 40 (93% [95% CI, 81% to 99%]) patients. Primary site CR was documented in 24 (54%) of patients. Postchemotherapy primary site biopsies were performed in 25 patients (58%) and pathologically negative biopsy was obtained in 11 (92%) of 12 primary site clinical CRs and seven (54%) of 13 with PR or no change. Overall, negative biopsies were obtained in 18 patients (72%). CONCLUSION: TPF induction chemotherapy can be delivered safely with a cisplatin dose of 100 mg/m(2) in previously untreated patients with SCCHN. The regimen is associated with a high rate of primary site clinical and pathologic CRs. Phase III comparison with cisplatinum and fluorouracil chemotherapy is warranted.

Adult↗

PubMed2001

Targeting growth factor receptors: integration of novel therapeutics in the management of head and neck cancer.

Tyrosine kinase (type 1) growth factor receptors include the erbB family. These cell surface receptors were discovered in the context of cellular transformation and have subsequently been found to be overexpressed in many types of human cancer. Cumulative evidence suggests that upregulation of the most well-characterized receptor, erbB1, also known as the epidermal growth factor receptor, plays a significant role in the development and progression of head and neck squamous cell carcinoma. A variety of strategies have been developed that specifically target epidermal growth factor receptor, including monoclonal antibodies, ligand-linked immunotoxins, tyrosine kinase inhibitors, and antisense approaches. Epidermal growth factor receptor blockade in head and neck squamous cell carcinoma cell lines and preclinical animal models inhibits cell proliferation and tumor growth. Clinical trials are under way to test the safety and efficacy of many of these targeting strategies in head and neck squamous cell carcinoma patients. Encouraging preliminary results combining an epidermal growth factor receptor targeting approaches with chemotherapy or radiotherapy suggest that interference with this growth factor receptor may enhance antitumor efficacy of standard therapies. As erbB family member interactions and downstream signaling pathways are elucidated in head and neck squamous cell carcinoma, specific targeting strategies may become incorporated into standard treatment approaches.

Carcinoma, Squamous Cell↗

PubMed2001

Recent advances in the management of squamous cell carcinoma of the head and neck.

Therapeutic outcomes of the currently used chemotherapeutic agents for recurrent or advanced head and neck squamous cell carcinoma, such as methotrexate or a combination of 5-fluorouracil and cisplatin, are far beyond satisfaction. New chemotherapeutic agents, such as taxanes, paclitaxel and docetaxel, are among the most active drugs for head and neck cancer and a number of multidrug regimens containing a taxane and cisplatin have produced equivalent or higher response rates than conventional regimens. In addition, early clinical trials of novel molecular-targeted agents, such as epidermal growth factor receptors, tyrosine kinase inhibitors and gene targeted therapy, have shown encouraging results. Further clinical trials will be needed to optimally combine the biologic agents with chemotherapy and assess their effects on long-term control of cancer.

Carcinoma, Squamous Cell↗

PubMed2001

Chromosome polysomy and histological characteristics in oral premalignant lesions.

Head and neck tumorigenesis has been postulated to represent a multistep process driven by the accumulation of carcinogen-induced genetic changes throughout the exposed tissue field. To better explore this genetic instability process at the tissue level, 59 regions within 26 biopsy tissue specimens from individuals with oral leukoplakia have been subjected to chromosome 9 in situ hybridization analysis, and the degree of chromosome instability was related to known clinical/pathological parameters associated with tumor risk. Whereas chromosome indices were similar between high-risk lesion sites and low-risk lesion sites, high-risk lesions showed higher levels of chromosome polysomy than did low-risk sites [median PIs (polysomy indices), 2.1 versus 1.4, respectively]. Similarly, dysplastic regions showed significantly higher chromosome polysomy levels than hyperplastic regions (median PIs, 2.4 versus 1.5, respectively). Interestingly, however, hyperplastic regions in the same biopsy as dysplastic regions showed two-times higher polysomy levels than those in biopsies without dysplasia (median PIs, 2.6 versus 1.3, respectively), suggesting that chromosome polysomy determinations provide a field measurement for the degree of ongoing genetic insult. Finally, chromosome polysomy tended to persist or increase in the superficial epithelial layers in regions showing koilocytosis, whereas their frequency decreased in nonkoilocytotic regions, suggesting that epigenetic factors may serve to perpetuate the levels of genetically unstable cells in the epithelium. These results provide direct support for the field cancerization process and suggest that measurements of genetic instability might provide additional biological information beyond histology and lesion site characteristics in the assessment of head and neck cancer risk.

Adult↗

PubMed2001

Epidermal growth factor receptor-targeted therapy with C225 and cisplatin in patients with head and neck cancer.

C225, a human-mouse chimerized monoclonal antibody directed against the epidermal growth factor receptor (EGFr), has a synergistic effect with cisplatin in xenograft models. To determine the tumor EGFr saturation dose with C225 and the fate of infused C225, we conducted a Phase Ib study with C225 in combination with cisplatin in patients with recurrent squamous cell carcinoma of the head and neck. Using tumor samples, we assessed tumor EGFr saturation by antibody using immunohistochemistry studies, the EGFr tyrosine kinase assay, and detection of the EGFr/C225 complex formation by immunoblot. Potential candidates were screened for EGFr expression in their tumors, and 12 patients who had high levels of EGFr expression and tumors easily accessible for repeated biopsies (pretherapy, 24 h after first C225 infusion, 24 h before third C225 infusion) were entered at three different dose levels of C225 with a fixed dose of cisplatin. The median value of tumor EGFr saturation increased to 95% at the higher dose levels. EGFr tyrosine kinase activity was significantly reduced after C225 infusion, and EGFr/C225 complexes were also detected at higher doses of C225. The loading dose of C225 at 400 mg/m(2) with a maintenance dose at 250 mg/m(2) achieved a high percentage of saturation of EGFr in tumor tissue, and these doses were recommended for Phases II or III clinical trials. Six (67%) of nine evaluable patients achieved major responses, including two (22%) complete responses. Mild to moderate degrees of allergic reaction and folliculitis-like skin reactions were demonstrated. We conclude that infused C225 binds and significantly saturates tumor EGFr, which may render a high degree of antitumor activity, and provides a novel mechanism for targeting cancer therapy for patients who have EGFr expression in their tumors.

Adult↗

PubMed2001

p53 protein accumulation and genomic instability in head and neck multistep tumorigenesis.

Head and neck cancer develops in a multistep process and is associated with increasing frequencies of p53 alterations and with increasing genomic instability. To study the relationship of p53 alterations and genomic instability during head and neck tumorigenesis, we analyzed p53 protein expression and chromosome 9 and 17 polysomy in 48 squamous cell carcinomas of the head and neck and their adjacent normal epithelium (31 sites), hyperplastic (24 sites), and dysplastic lesions (26 sites). Normal oral epithelium obtained from seven nonsmoking, cancer-free individuals served as negative controls. Six (19%) of 31 lesions in adjacent normal epithelium, 7 (29%) of 24 hyperplastic lesions, 12 (46%) of 26 dysplastic lesions, and 28 (58%) of 48 squamous cell carcinomas expressed p53. In contrast, no normal control epithelium had detectable p53 expression. To determine the relationship between dysregulated p53 expression and genomic instability during tumorigenesis, we compared p53 immunohistochemistry distributions and chromosome polysomy levels (by chromosome in situ hybridization) in different histological groups associated with tissue progression. Although the degree of chromosome polysomy increased for all of the groups during histological progression, lesions with dysregulated p53 expression showed nearly 2-4-fold increased levels of chromosome polysomy. This trend was significant for dysplastic lesions (P = 0.005 and P = 0.002 for chromosomes 9 and 17, respectively) and for squamous cell carcinoma (P = 0.005 and P = 0.002 for chromosomes 9 and 17, respectively). Image analysis studies for 28 p53-expressing tumors and their adjacent premalignant lesions demonstrated a strong spatial correlation between stepwise transitions from low to high p53 expression and increased chromosome polysomy frequencies in 13 (46%) of 28 cases. These findings suggest that altered p53 expression is associated with increased genetic instability in preneoplastic epithelium and may play a driving force for increasing the rate of accumulation of genetic events during head and neck tumorigenesis.

Aneuploidy↗

PubMed2001

Cyclin D1 and p16 alterations in advanced premalignant lesions of the upper aerodigestive tract: role in response to chemoprevention and cancer development.

PURPOSE: To better understand the role of G(1)-S transition regulator abnormalities in the pathogenesis of advanced premalignant lesions of the upper aerodigestive tract and the biological effects of chemoprevention, we studied biopsies obtained sequentially from participants in a prospective trial using 13-cis retinoic acid, IFN-alpha, and alpha-tocopherol for 12 months. EXPERIMENTAL DESIGN: Cyclin D1 and p16 expression were analyzed by immunohistochemistry, loss of heterozygosity by polymerase chain reacting amplification, and then electrophoretic separation of the products, methylation of the p16 promoter by methylation-specific polymerase chain reacting, and cyclin D1 gene amplification by fluorescence in situ hybridization. RESULTS: Baseline dysregulation of cyclin D1 expression was found in 50% (14 of 28) and was reversed in 6 of 14 cases, whereas p16 expression was lost in 46% (13 of 28) and regained in 2 of 13 cases. Loss of heterozygosity at 9p21 occurred in 68% and p16(INK4a) promoter methylation occurred in 75% of cases, with increasing frequency from mild to severe dysplasia. Cyclin D1 gene amplification was identified in two cases. Cyclin D1 protein dysregulation at last follow-up alone and in combination with p16 loss was associated with histological progression and cancer development (P < 0.01). CONCLUSIONS: Additional study of these alterations in a larger sample and exploration of the upstream signaling partners of these cell cycle regulators in vivo is warranted to identify cancer risk profiles that would be meaningful targets for chemopreventive intervention.

Adult↗

PubMed2000

Visualization of the timing of gene amplification during multistep head and neck tumorigenesis.

Head and neck tumorigenesis is thought to represent a multistep process whereby carcinogen exposure leads to genetic instability in the tissue and the accumulation of specific genetic events, which result in dysregulation of proliferation, differentiation, and cell loss and the acquisition of invasive capacity. Chromosome 11q13 amplification is frequently observed in head and neck squamous cell carcinoma (HNSCC), and the amplified gene products are assumed to play important functional roles in the tumor phenotype. However, it is not well understood whether gene amplification precedes carcinoma development or results from the unstable nature of intact tumors. To determine the timing of gene amplification during tumorigenesis, tissue sections from amplified HNSCC specimens (containing a contiguous transition from normal epithelium to hyperplasia to dysplasia to carcinoma) were probed for INT2 gene copy number by chromosome in situ hybridization. In addition, representative epithelia were microdissected from the tissue sections, and the DNA was isolated and assessed for INT2 gene copy number by semiquantitative PCR. In those cases containing amplified INT2 in the carcinoma, gene amplification appeared to precede HNSCC development. In one case, INT2 gene amplification appeared in the hyperplasia to dysplasia transition, whereas in two other cases, gene amplification was apparent at dysplasia. These results suggest that gene amplification can occur early during head and neck tumorigenesis and that genetic instability is an important driving force in the tumorigenesis process.

Carcinoma, Squamous Cell↗