Upstream stimulatory factor (USF) as a transcriptional suppressor of human telomerase reverse transcriptase (hTERT) in oral cancer cells

Telomerase activity is suppressed in normal human somatic tissues but is activated in cancer cells and immortal cell lines. The reverse transcriptase (RT) subunit human telomerase reverse transcriptase (hTERT) is the key regulator of telomerase activity. The hTERT promoter contains E-box elements and may allow upstream stimulatory factor (USF), a basic helix-loop-helix (bHLH) leucine zipper family proteins, to bind and regulate the expression. In this study, we investigated whether and how USF effect on hTERT. Through luciferase reporter assays, we found that both USF1 and USF2 possess a comparable effect on the inhibition of hTERT expression. Immunoprecipitation (IP) and immunoblotting (IB) analysis reveal that the suppression of hTERT by USF was not through the interaction of USF with c-myc or mad, nor disturbed the cellular protein levels of those. In gel mobility shift and chromatin immunoprecipitation (CHIP) assays, we found that the USF suppression is through direct binding at the E-box site of hTERT promoter and rendering the effect actively. Analysis on clinical normal and tumor tissues reveal that the expression of USF1 and USF2 was lower in the tumor tissues, correlated with hTERT expression and telomerase activity. Taking together, our results demonstrate that USF is a negative transcriptional repressor for hTERT in oral cancer cells. It is possible that USF lose the inhibitory effect on hTERT expression leading to telomerase reactivation and oral carcinogenesis.

Are dual-phase 18F-FDG PET scans necessary in nasopharyngeal carcinoma to assess the primary tumour and loco-regional nodes?

PURPOSE

This prospective study aimed to investigate the efficacy of dual-phase positron emission tomography (PET) in evaluating the loco-regional status of nasopharyngeal carcinoma (NPC).

METHODS

Eighty-four patients with newly diagnosed NPC and a fasting serum glucose level of <200 mg/dl were enrolled. [18F]fluoro-2-deoxy-D-glucose (18F-FDG) PET studies (at 40 min and 3 h after injection of 370 MBq 18F-FDG) and head and neck magnetic resonance imaging (MRI) were performed within 1 week. Diagnostic criteria for NPC comprised the histopathological findings, the joint judgments of the research team and the post-treatment outcome. Each lesion's maximum standardised uptake value (SUV) and retention index were obtained. SUV data were evaluated using a paired t test. Receiver operating characteristic curves and calculation of the area under the curve (AUC) determined the discriminative power.

RESULTS

18F-FDG PET was significantly superior to MRI in identifying lower neck NPC nodal metastasis (AUC: 1 vs 0. 972, P=0.046) and overall loco-regional metastases (AUC: 0.985 vs 0.958, P=0.036). However, 18F-FDG PET was similar to MRI in detecting primary tumour, as well as retropharyngeal, upper neck and supraclavicular nodal metastases. There was no significant difference between early phase (40 min) and delayed phase (3 h) 18F-FDG PET in the detection of primary tumours (accuracy: 100% vs 100%) or loco-regional nodal metastasis (AUC: 0.984 vs 0.985, P=0.834).

CONCLUSION

18F-FDG PET is superior to MRI in identifying lower neck nodal metastasis of NPC. Additional 3-h 18F-FDG PET contributes no further information in the detection of primary tumours or loco-regional metastatic nodes in untreated NPC patients.

Telomerase as an independent prognostic factor in head and neck squamous cell carcinoma

BACKGROUND

Telomerase activity has been found to be associated with many cancers, including head and neck squamous cell carcinoma (HNSCC). We examined the association of telomerase activity with the clinical outcome of patients with HNSCC.

METHODS

A PCR-based enzyme immunoassay method was used to measure telomerase activity in 217 matched (grossly normal and cancerous) tissues from patients with HNSCC. Pearson chi-square test was used to analyze the correlation of telomerase activity with clinicopathologic parameters. Kaplan-Meier method and Cox logistic regression model were used for prognostic analysis.

RESULTS

Of the 217 tissues assayed, 4.1% of the normal and 63.3% of the cancer tissues had high levels of telomerase activity. Telomerase activity was shown to be statistically correlated with extracapsule spreading (ECS) of lymph nodes (p =.005) and overall survival (p =.003). On multivariant analysis, overall stage (p =.007), tumor depth (p =.045), and telomerase activity (p =.008) showed independent variables associated with poor survival.

CONCLUSIONS

Telomerase activity has been shown to be an independent prognostic factor for survival in cases of HNSCC. Telomerase may be a potential molecular target for clinical use in prognostication and therapy in cases of the disease.

Recent advances in the treatment of nasopharyngeal carcinoma

The outcome of nasopharyngeal carcinoma (NPC) treatment has greatly improved as advances in imaging techniques increase the accuracy of tumor mapping. Radiotherapy remains a common treatment for early disease, while concurrent chemoradiotherapy is being increasingly accepted as the standard treatment for advanced disease. Intensity modulation radiotherapy (IMRT) delivers a more conformal radiation dose to the target area and may spare normal organs such as parotid gland for patients with early stage disease. IMRT in conjunction with concurrent chemotherapy offers excellent tumor control with fewer complications. These benefits suggest it will become the mainstay of radiotherapy treatment for NPC. Prevention of distant metastasis remains a crucial objective. The potential of induction chemotherapy to reduce distant metastasis has gained increased attention. Adjuvant chemotherapy has been unsuccessful due to poor tolerability. For metastatic NPC, cisplatin-based chemotherapy is effective but limited by cumulative toxicities. Newer drugs such gemcitabine and vinorelbine have been shown to be active in salvage therapy when cisplatin-containing combinations have failed. Due to their advantageous toxicity profiles, new drugs may replace cisplatin-based combinations as first-line treatment for metastatic NPC in the near future. Signal transduction manipulation is promising but has not been shown to be an essential therapy. Immunotherapy, such as mini-transplant, may offer the chance for durable control without long-term treatment, but its efficacy remains to be demonstrated.

Fluoroscopically guided percutaneous gastrostomy with modified gastropexy and a large-bore balloon-retained catheter in patients with head and neck tumors

PURPOSE

To report on fluoroscopically guided percutaneous gastrostomy (FPG) using a modified gastropexy technique with the insertion of a large-bore balloon-retained gastrostomy catheter in patients with head and neck tumors.

MATERIAL AND METHODS

Thirty-four patients with head and neck tumors underwent a modified gastropexy with two T-fasteners followed by the insertion of a 14-F ballooon-retained catheter through a peel-away introducer. The success rate and the complications of the procedures were evaluated at 14 days, 30 days, and 60 days. The complications were classified as: major complications that necessitated intensive and/or surgical treatment; minor complications that could be treated conservatively; and tube-related complications manageable by tube exchange.

RESULTS

FPG was technically successful in all cases. There were no major complications, two minor complications where superficial stoma infection was controlled by antibiotics, three minor tube-related complications, all three easily managed by catheter replacement via the original tract.

CONCLUSION

FPG with insertion of a large-bore balloon-retained catheter using a modified gastropexy technique is a safe and effective method that creates a feeding access for patients with head and neck tumors and esophageal obstruction. Minor complications can be managed conservatively. FPG may be a good alternative to surgical or percutaneous endoscopic gastrostomy.

Nodal metastases of nasopharyngeal carcinoma: patterns of disease on MRI and FDG PET

The patterns of nodal spread of nasopharyngeal carcinoma (NPC) have an important influence on treatment planning, but have not yet been fully addressed. We prospectively used MRI and FDG PET to document the patterns of nodal spread in NPC. One hundred and one patients with newly diagnosed NPC were studied with MRI and FDG PET. On MRI, nodes were considered as metastatic according to criteria regarding size, the presence of nodal necrosis, and extracapsular spread. FDG PET images were interpreted visually, and nodes were considered metastatic if they showed prominent FDG uptake against the background. Nodal metastases were found in 89 of our 101 patients. Analysis of the distributions of nodal metastases in these 89 patients showed that retropharyngeal nodes were less frequently involved than cervical nodes (82.0% vs 95.5%). The vast majority of cervical nodal metastases were to the internal jugular chain, including nodes at levels II, III, and IV, with decreasing incidences of 95.5%, 60.7%, and 34.8%, respectively. Level V nodal involvement was found in 27% of patients. Supraclavicular fossa nodal metastases were not uncommon and occurred in 22.5% of patients. Skip metastases in the lower-level nodes or supraclavicular fossa nodes occurred in 7.9% of patients. Mediastinal and abdominal metastatic adenopathy was present in 4.5% and 3.4% of patients, respectively, and was associated with advanced nodal metastasis in the supraclavicular fossa. Level VI (2.2%), level VII (1.1%), submandibular (2.2%), and parotid (3.4%) nodal metastases were uncommon and were always associated with advanced ipsilateral nodal metastases of the neck. We conclude that the combined use of FDG PET and MRI can comprehensively depict the pattern of nodal metastasis in NPC patients. Nodal metastases principally affected level II nodes, from which lymphatic spread extended down in an orderly manner to involve level III, level IV, and the supraclavicular fossa nodes, or extended posteriorly to involve level V nodes. The frequency of skip metastases was 7.9%. Distant spread to mediastinal or abdominal nodes was found in 3-5% of patients, usually in association with supraclavicular nodal metastases.

Contemporary management of penile cancer including surgery and adjuvant radiotherapy: an experience in Taiwan

This retrospective study reports on the treatment outcomes of 45 men with penile cancer and seeks to address the issue concerning the treatment of inguinal lymph nodes (LN). Of these 45 patients, five had verrucous carcinoma and the other 40 had squamous cell carcinoma. Eighteen patients had inguinal lymph nodes (LNs) metastasis and received treatments of inguinal LNs involving bilateral inguinal LN dissection or unilateral inguinal LN dissection with or without postoperative radiotherapy. The median follow-up was 37 months. The ultimate local and regional controls for patients with verrucous carcinoma were 100 and 100%, respectively. Among the 40 patients with squamous cell carcinoma, the overall local control rate was 90%. The 5-year overall survival (OS) and disease-free survival (DFS) rates of patients without or with pathological inguinal LN metastasis were 70 vs. 22% (p=0.01), and 55 vs. 16% (p=0.004), respectively. The regional failure rates after inguinal LN dissection for pathological inguinal LN metastasis were 11% (1/9) and 60% (3/5) in patients with and without adjuvant radiotherapy. This study demonstrates that verrucous carcinoma shows excellent treatment outcomes following surgery alone. Squamous cell carcinoma of the penis is associated with a high incidence of inguinal lymph node metastasis. Elective groin dissection is indicated for all penile cancer patients except those with verrucous carcinoma and pT1 cancer with well-differentiated tumor. For patients with pathologically positive inguinal LN metastasis, adjuvant radiotherapy can increase inguinal control in this study. It warrants further prospective trial to prove the value of adjuvant radiotherapy in patients with pathological documented inguinal LN metastasis in penile cancer.

Surgical treatment of oral verrucous carcinoma

BACKGROUND

The aim of this study was to evaluate the outcome of patients with Verrucous carcinoma (VC) of oral cavity treated at the Chung Gung Memory Hospital with respect to the tumor control rates after surgery, the risk of lymph node metastasis and the role of radiation therapy.

METHODS

Thirty-eight patients underwent primary treatment for VC of the oral cavity from January 1996 through February 2002. All of the patients had surgery as their primary treatment. In addition, all patients with sufficient details of the therapy and a minimum 1-year follow-up were selected for evaluation of survival and outcomes.

RESULTS

In this study, 94.7% of patients were male and most of them had been exposed to betel nuts, cigarettes, and/or alcohol. The most common site was the buccal mucosa (57.9%), followed by the tongue (13.2%). T3 lesions were the most common type (34.2%). Only two patients had palpable cervical adenopathy during the initial evaluation. Twenty-five patients had free flap for reconstruction. The tumor control rate was 100%. At the time of analysis, no patient had suffered from recurrence in primary site or neck area.

CONCLUSION

Surgical excision alone was effective for controlling VC, but elective neck dissection was not necessary even in patients in the advanced stages.

Lack of correlation of betel nut chewing, tobacco smoking, and alcohol consumption with telomerase activity and the severity of oral cancer

BACKGROUND

Oral cancer is one of the most frequent cancers. A strong association has been found between oral cancer incidence and the use of betel nut, alcohol, and tobacco. Telomerase activity (TA) has also been shown to play a role in carcinogenesis. We therefore surveyed the consumption habits of betel nut chewing, alcohol drinking, and tobacco smoking in oral cancer patients and evaluated the association of these habits with TA level and clinical stage.

METHODS

In total, 154 oral cancer patients were recruited. TA was measured in paired (grossly normal and cancerous) tissues using a polymerase chain reaction-based enzyme immunoassay. Associations of these factors with clinical stage and TA level were analyzed using the Pearson chi-square test.

RESULTS

In these patients, 86.4%, 61.0%, and 83.3% used betel nut, alcohol, and tobacco, respectively. For all tissue assayed, 80.5% of cancerous and 3.2% of grossly normal mucosae were positive for TA. However, neither clinical stage nor TA level in cancerous tissues had a statistical association with the use of individual substances (betel nut, alcohol, and tobacco) or their combined use.

CONCLUSION

Even though the habitual uses of these substances have been previously reported to be associated with oral cancer incidence, we found a lack of correlation with TA level or with disease severity in our study. These results imply that these consumption habits might only be associated with the early stages of oral cancer development, while the later stages of cancer progression may be more associated with other external factors or dependent on host cellular factors, all of which require confirmation through further investigations.

The XRCC1 399Gln polymorphism and the frequency of p53 mutations in Taiwanese oral squamous cell carcinomas

DNA repair gene polymorphisms have been implicated as susceptibility factors in cancer development. It is possible that DNA repair polymorphisms may also influence the risk of gene mutation. The 399Gln polymorphism in the DNA repair gene XRCC1 has been indicated to have a contributive role in DNA adduct formation, sister chromatid exchange, and an increased risk of cancer development. Two hundred thirty-seven male oral squamous cell carcinomas (OSCCs) were included in a study to investigate the role of the XRCC1 194Trp, 280His, and 399Gln polymorphisms on p53 gene mutation. PCR-single-strand conformation polymorphism and DNA sequencing were used to analyze the conserved regions of the p53 gene (exons 5-9). The XRCC1 genotype was determined by PCR-RFLP. Nineteen (8.02%) of the 237 OSCCs had a Gln/Gln genotype. One hundred six (43.88%) of the 237 OSCCs showed p53 gene mutations at exons 5-9. The OSCC patients with a Gln/Gln genotype exhibited a significantly higher frequency of p53 mutation than those with an Arg/Gln and an Arg/Arg genotype. After adjustment for age, cigarette smoking, areca quid chewing, and alcohol drinking, the Gln/Gln genotype still showed an independent association with the frequency of p53 mutation (odd ratio, 4.50; 95% confidence interval, 1.52-13.36). The findings support the hypothesis that XRCC1 Arg399Gln amino acid change may alter the phenotype of the XRCC1 protein, resulting in a DNA repair deficiency. This study also suggests an important role for the XRCC1 399Gln polymorphism in p53 gene mutation in Taiwanese OSCCs.

Quantitative analysis of multidrug-resistance mdr1 gene expression in head and neck cancer by real-time RT-PCR

Progression of head and neck cancer is always associated with changes of gene expression profile. In this study, we characterized the expression of multidrug-resistance mdr1 gene, which may play a role in tumorigenesis and multidrug resistance in head and neck cancer. A TaqMan one-step RT-PCR with a linear range for quantification across at least a 5 log scale of concentration of mdr1 mRNA was designed to determine the level of mdr1 expression in 50 pairs of normal vs. malignant head and neck tissues. Both the absolute level of mdr1 mRNA in tumor (T) and the relative mdr1 expression between tumor and its normal counterpart (T/N) were measured and their associations with several clinical variables were analyzed. Among the clinical variables analyzed, only the clinical stage of tumor was found to be associated with mdr1 expression. The distribution of clinical stages differed significantly (P<0.01) among the 27 specimens that had a T/N>1, with 59.3%, 22.2%, 14.8% and 3.7% in stage IV, III, II, and I, respectively. In addition, 76% of stage IV and 75% of stage III tumors had a T/N>1 compared to 25% of stage II and 20% of stage I tumors (P=0.004). Multivariate logistic regression analysis also indicated a significant difference of mdr1 expression between the early (I and II) and advanced (III and IV) stages tumors. The adjusted odds ratios (95% confidence intervals) were 1.477 (1.084 - 2.012) and 1.001 (1.000-1.002) for T/N (P<0.05) and T (P<0.05) treated as continuous variables, and 15.521 (3.414-70.550) and 5.074 (1.154-22.311) for T/N (P<0.001) and T (P<0.05) treated as binary variables, respectively. Taken together, the data presented here indicated that real-time RT-PCR provides a quantitative way to monitor mdr1 gene expression. The differential expression of mdr1 between early and advanced stages of head and neck cancer may shed light on the process of tumorigenicity and offer clues to the planning of new treatments.

Differential regulation of telomerase activity by six telomerase subunits

Telomerase is a specialized reverse transcriptase responsible for synthesizing telomeric DNA at the ends of chromosomes. Six subunits composing the telomerase complex have been cloned: hTR (human telomerase RNA), TEP1 (telomerase-associated protein 1), hTERT (human telomerase reverse transcriptase), hsp90 (heat shock protein 90), p23, and dyskerin. In this study, we investigated the role of each the telomerase subunit on the activity of telomerase. Through down- or upregulation of telomerase, we found that only hTERT expression changed proportionally with the level of telomerase activity. The other components, TEP1, hTR, hsp90, p23, and dyskerin remained at high and unchanged levels throughout modulation. In vivo and in vitro experiments with antisense oligonucleotides against each telomerase component were also performed. Telomerase activity was decreased or abolished by antisense treatment. To correlate clinical sample status, four pairs of normal and malignant tissues from patients with oral cancer were examined. Except for the hTERT subunit, which showed differential expression in normal and cancer tissues, all other components were expressed in both normal and malignant tissues. We conclude that hTERT is a regulatable subunit, whereas the other components are expressed more constantly in cells. Although hTERT has a rate-limiting effect on enzyme activity, the other telomerase subunits (hTR, TEP1, hsp90, p23, dyskerin) participated in full enzyme activity. We hypothesize that once hTERT is expressed, all other telomerase subunits can be assembled to form a highly active holoenzyme.