Important prognostic factors of long-term oropharyngeal carcinoma survivors in Taiwan

Design and application of metal organic frameworks for heavy metals adsorption in water: a review

The growing apprehension surrounding heavy metal pollution in both environmental and industrial contexts has spurred extensive research into adsorption materials aimed at efficient remediation. Among these materials, Metal-Organic Frameworks (MOFs) have risen as versatile and promising contenders due to their adjustable properties, expansive surface areas, and sustainable characteristics, compared to traditional options like activated carbon and zeolites. This exhaustive review delves into the synthesis techniques, structural diversity, and adsorption capabilities of MOFs for the effective removal of heavy metals. The article explores the evolution of MOF design and fabrication methods, highlighting pivotal parameters influencing their adsorption performance, such as pore size, surface area, and the presence of functional groups. In this perspective review, a thorough analysis of various MOFs is presented, emphasizing the crucial role of ligands and metal nodes in adapting MOF properties for heavy metal removal. Moreover, the review delves into recent advancements in MOF-based composites and hybrid materials, shedding light on their heightened adsorption capacities, recyclability, and potential for regeneration. Challenges for optimization, regeneration efficiency and minimizing costs for large-scale applications are discussed.

Micro-RNAs: Crossroads between the Exposure to Environmental Particulate Pollution and the Obstructive Pulmonary Disease

Environmental pollution has reached a global echo and represents a serious problem for human health. Air pollution encompasses a set of hazardous substances, such as particulate matter and heavy metals (e.g., cadmium, lead, and arsenic), and has a strong impact on the environment by affecting groundwater, soil, and air. An adaptive response to environmental cues is essential for human survival, which is associated with the induction of adaptive phenotypes. The epigenetic mechanisms regulating the expression patterns of several genes are promising candidates to provide mechanistic and prognostic insights into this. Micro-RNAs (miRNAs) fulfil these features given their ability to respond to environmental factors and their critical role in determining phenotypes. These molecules are present in extracellular fluids, and their expression patterns are organ-, tissue-, or cell-specific. Moreover, the experimental settings for their quantitative and qualitative analysis are robust, standardized, and inexpensive. In this review, we provide an update on the role of miRNAs as suitable tools for understanding the mechanisms behind the physiopathological response to toxicants and the prognostic value of their expression pattern associable with specific exposures. We look at the mechanistic evidence associable to the role of miRNAs in the processes leading to environmental-induced pulmonary disease (i.e., chronic obstructive pulmonary disease).

Adverse Health Effects of Betel Quid and the Risk of Oral and Pharyngeal Cancers

Global reports estimate 600 million betel quid (BQ) chewers. BQ chewing has been demonstrated not only to be a risk factor for cancers of the oral cavity and pharynx and oral potentially malignant disorders (OPMD) but also to cause other cancers and adverse health effects. Herein, we summarized the international comparison data to aid in the understanding of the close relationship between the prevalence of BQ chewing, the occurrence of oral and pharyngeal cancers, and adverse health effects. Potential biomarkers of BQ carcinogens, such as areca nut, alkaloids, and 3-methylnitrosaminopropionitrile (MNPN), are closely associated with human health toxicology. Molecular mechanisms or pathways involving autophagy, hypoxia, COX-2, NF-κB activity, and stemness are known to be induced by BQ ingredients and are very closely related to the carcinogenesis of cancers of oral and pharynx. BQ abuse-related monoamine oxidase (MAO) gene was associated with the occurrence and progress of oral and pharyngeal cancers. In summary, our review article provides important insights into the potential roles of environmental BQ (specific alkaloid biomarkers and nitrosamine products MNPN) and genetic factors (MAO) and offers a basis for studies aiming to reduce or eliminate BQ-related OPMD and oral/pharyngeal cancer incidences in the future.

Prevalence of exposure of heavy metals and their impact on health consequences

Even in the current era of growing technology, the concentration of heavy metals present in drinking water is still not within the recommended limits as set by the regulatory authorities in different countries of the world. Drinking water contaminated with heavy metals namely; arsenic, cadmium, nickel, mercury, chromium, zinc, and lead is becoming a major health concern for public and health care professionals. Occupational exposure to heavy metals is known to occur by the utilization of these metals in various industrial processes and/or contents including color pigments and alloys. However, the predominant source resulting in measurable human exposure to heavy metals is the consumption of contaminated drinking water and the resulting health issues may include cardiovascular disorders, neuronal damage, renal injuries, and risk of cancer and diabetes. The general mechanism involved in heavy metal-induced toxicity is recognized to be the production of reactive oxygen species resulting oxidative damage and health related adverse effects. Thus utilization of heavy metal-contaminated water is resulting in high morbidity and mortality rates all over the world. Thereby, feeling the need to raise the concerns about contribution of different heavy metals in various health related issues, this article has discussed the global contamination of drinking water with heavy metals to assess the health hazards associated with consumption of heavy metal-contaminated water. A relationship between exposure limits and ultimate responses produced as well as the major organs affected have been reviewed. Acute and chronic poisoning symptoms and mechanisms responsible for such toxicities have also been discussed.

Differences in oral habit and lymphocyte subpopulation affect malignant transformation of patients with oral precancer

BACKGROUND/PURPOSE

In Taiwan, the combination of betel quid chewing, alcohol consumption, and smoking habits increases oral cancer risk by 123-fold compared to persons without these habits. Lymphocyte populations in patients may potentially affect the malignant transformation of oral precancer.

METHODS

A total of 28 patients with oral precancer from our previous cohort were enrolled in this study, and their personal information and oral habits were documented. Their lymphocyte populations (CD4+, CD8+, CD19+, and CD56+) and activation markers (CD25 and CD69) were determined by flow cytometry from 1999 to 2004. After follow up till December 2014, data of patients with/without malignant transformation were recorded, and the relation between oral habits and percentage of initial lymphocyte markers was evaluated using the Student t test and Fisher's exact test.

RESULTS

Ten precancer patients developed oral squamous cell carcinoma with a mean period of malignant transformation of 6.8 ± 2.1 years. Patients with malignant transformation had a mean age of 48.4 ± 5.0 years (n = 10), relatively more than that of patients without malignant transformation (41.6 ± 6.3 years, n = 18) (p < 0.05). An increase was noted in the population of peripheral blood mononuclear cells expressing CD4+CD69+, CD19+CD69+, and CD56+CD69+ (p < 0.05) in precancer patients with malignant transformation. Alcohol consumption showed an association with the malignant transformation of patients with precancer (p = 0.030), whereas betel quid and smoking showed little effect.

CONCLUSION

These results suggest that age, alcohol consumption, and early activation of T cells, B cells, and natural killer cells are crucial in the malignant transformation of oral precancer. Analysis of patient's lymphocyte populations may help predict the malignant transformation of oral precancer.

Cancers of upper gingivobuccal sulcus, hard palate and maxilla: A tertiary care centre study in North India

Introduction:

Oral cancer is the sixth most common malignancy in the world, and the third most common in southeast Asia. Cancers of the upper gingivo-buccal complex are uncommon and reported infrequently. In this article, we have assessed the clinicopathological features of such cancers and their optimal management.

Materials and Methods:

We studied 64 patients with cancer of the upper gingivobuccal sulcus (GBS), hard palate, and maxilla seen between February 2009 and 2013 over a span of 4 years.

Results:

Of the 64 patients studied, 45 were male. The mean age at presentation was 50.59 years (24-80 years). Of the 64, 48 patients (75%) had a history of substance abuse in the form of tobacco chewing, smoking or alcohol. On presentation, 48 of the 64 patients (75%) had T4 disease, eight had T3, six had T2 lesion, one had T1 lesion, and 1 patient had a neck recurrence with distant metastatic disease (Tx). Out of the 64 patients, 31 had clinically palpable neck disease and two patients had distant metastatic disease. Of the 64 patients, 58 had squamous cell carcinoma, two had adenoid cystic carcinoma of the hard palate and one patient each had melanoma, sarcoma, neuroendocrine tumor, and mucoepidermoid carcinoma. Following imaging, 18 patients (28.13%) underwent upfront surgery and six following neoadjuvant chemotherapy. 14 of the 24 patients operated had simultaneous neck dissection. 2 patients with distant metastasis and 1 with cavernous sinus thrombosis received palliative chemotherapy. Out of the 64 patients, the other 24 who were inoperable were referred to radiotherapy.

Conclusion:

Upper GBS, hard palate and maxilla cancers are uncommon and are diagnosed at an advanced stage due to delay in presentation and ignorance of our population. Surgery offers the best form of treatment. NACT may be tried to downstage the disease in selected patients with borderline operable disease. However, generous margins should be taken post chemotherapy with concomitant neck dissection. Adjuvant radiotherapy is recommended in selected patients after surgery.

Cytochrome p450 metabolism of betel quid-derived compounds: implications for the development of prevention strategies for oral and pharyngeal cancers

Betel quid (BQ) products, with or without tobacco, have been classified by the International Agency for Research on Cancer (IARC) as group I human carcinogens that are associated with an elevated risk of oral potentially malignant disorders (OPMDs) and cancers of the oral cavity and pharynx. There are estimated 600 million BQ users worldwide. In Taiwan alone there are 2 million habitual users (approximately 10% of the population). Oral and pharyngeal cancers result from interactions between genes and environmental factors (BQ exposure). Cytochrome p450 (CYP) families are implicated in the metabolic activation of BQ- and areca nut-specific nitrosamines. In this review, we summarize the current knowledge base regarding CYP genetic variants and related oral disorders. In clinical applications, we focus on cancers of the oral cavity and pharynx and OPMDs associated with CYP gene polymorphisms, including CYP1A1, CYP2A6, CYP2E1, and CYP26B1. Our discussion of CYP polymorphisms provides insight into the importance of screening tests in OPMDs patients for the prevention of oral and pharyngeal cancers. Future studies will establish a strong foundation for the development of chemoprevention strategies, polymorphism-based clinical diagnostic tools (e.g., specific single-nucleotide polymorphism (SNP) "barcodes"), and effective treatments for BQ-related oral disorders.

Prognostic factors in head and neck squamous cell carcinoma: comparison of CHAID decision trees technology and Cox analysis

BACKGROUND

The purpose of this study was to compare the risk factors obtained from a classical statistical method (Cox proportional hazards model) and the results obtained with classification trees (Chi-square Automatic Interaction Detection [CHAID] model) in head and neck squamous cell carcinoma (HNSCC).

METHODS

We conducted a retrospective study of 3373 patients with HNSCC and a follow-up longer than 2 years.

RESULTS

The most decisive variable classified by CHAID was T category. N classification was an important prognostic factor in the Cox analysis, but this was not considered in CHAID except in T2 and supraglottic T3. CHAID also indicated that women with oral cavity T3/T4 to N0 tumors had poorer prognosis (28%) than men (58.5%; p value < .001). In oropharynx location, men had lower survival than women (41% vs 72%; p value < .001).

CONCLUSIONS

The main benefit of CHAID analysis is that it identifies a relatively small number of patients with a singular behavior, which is more discriminatory for an optimal diagnosis and treatment.

Reduced expression of TRF1 is associated with tumor progression and poor prognosis in oral squamous cell carcinoma

The functions of telomeric repeat-binding factor 1 (TRF1) and 2 (TRF2) in oral carcinogenesis are largely unexplored. This study examined the relationship between the expression of TRF1 and TRF2 and clinicopathological variables and survival in oral cavity squamous cell carcinoma (OCSCC). Western blotting and immunohistochemistry were used to evaluate the protein expression of TRF1 and TRF2 in paired OCSCC patient specimens. Expression of TRF1 and TRF2 was assessed by immunohistochemistry in 256 OCSCC patients who underwent tumor resection without previous radiotherapy. The results were analyzed using Fisher's exact test. Protein expression of TRF1 and TRF2 was significantly lower in the OCSCC than in the adjacent non-tumor tissue. Reduced TRF1 and TRF2 levels in 256 patients, as revealed by immunohistochemistry, were significantly associated with aggressive clinicopathological features, such as advanced tumor stage (p<0.001) and advanced tumor node metastasis stage (p<0.001). According to Kaplan-Meier analysis, reduced TRF1 expression was significantly correlated with an unfavorable cumulative 5-year overall survival rate (p<0.001). In conclusion, decreased expression of TRF1 was significantly associated with tumor progression and poor prognosis in OCSCC patients.

Therapeutic efficacy evaluation of curcumin on human oral squamous cell carcinoma xenograft using multimodalities of molecular imaging

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity; however the treatment approaches are still unsatisfactory. We used a luciferase-transfected animal model to evaluate the therapeutic effects of curcumin. Human oral squamous cell carcinoma SAS cell line was stably transfected with luc gene, named SAS/luc cells. For the in vivo study, they were inoculated subcutaneously to 6-week-old male NOD/SCID mice which were separated into four groups for intraperitoneal injection (i.p.) of curcumin: control, daily with 35 mg/kg, 70 mg/kg every 2 days, and 100 mg/kg every 3 days. We applied SAS/luc bearing animal model and bioluminescent imaging (BLI) to study the inhibition effect of curcumin on tumor growth. The cytotoxic effect of curcumin on SAS/luc cells was mainly at G2/M phase and a significant dose dependent increase of the apoptotic SAS/luc cells as represented by sub-G1 phase was shown. Therapeutic efficacy evaluated by both caliper assay and BLI showed a significant difference between curcumin-treated mice and the controls (p < 0.01). The significant inhibition effects of curcumin on the proliferation and the growth of human OSCC are observed both in vitro and in vivo. No significant body weight change (i.e. within 20%) was observed in all SAS/luc-bearing mice with or without curcumin treatment. This SAS/luc human OSCC bearing animal model combined with multimodalities of molecular imaging permits a sensitive and non-invasive approach to evaluate the therapeutic efficacy in vivo.

Identification of increased NBS1 expression as a prognostic marker of squamous cell carcinoma of the oral cavity

Oral squamous cell carcinoma (OSCC) is one of the most prevalent cancers worldwide; however, accurate molecular markers to predict its prognosis are still limited. We previously demonstrated that overexpression of the DNA double-strand break repair protein NBS1 is a prognostic marker of advanced head and neck squamous cell carcinoma (HNSCC). Therefore, we aimed to investigate the feasibility of using NBS1 as a biomarker in OSCC. In this study, we enrolled 148 OSCC for immunohistochemical (IHC) and clinical analysis. Data from 58 advanced non-oral-cavity HNSCC (NO-HNSCC) cases were also included for comparison due to the biological and clinical discrepancy between OSCC and HNSCC originated from the other sites (e.g. pharynx or larynx). First, we validated the NBS1 IHC results by real-time RT-PCR analysis, and an excellent correlation between the results of these two assays confirmed the reliability and robustness of IHC procedures and interpretation. NBS1 overexpression was an independent prognostic marker in both OSCC and NO-HNSCC cases. In OSCC, the prognostic significance of NBS1 was shown regardless of T stage and lymph node status. Increased NBS1 expression correlated with advanced T stage and recurrence/metastasis. NBS1 overexpression correlated with the phosphorylation levels of Akt and its downstream target mammalian target of rapamycin (mTOR). These results clearly illustrate the expression profile of NBS1 in OSCC and NO-HNSCC, and highlight the role of NBS1 in HNSCC irrespective of the primary sites. It also indicates the practicability of application of NBS1 as a marker in OSCC.

Incidence of oral cancer in relation to nickel and arsenic concentrations in farm soils of patients' residential areas in Taiwan

BACKGROUND

To explore if exposures to specific heavy metals in the environment is a new risk factor of oral cancer, one of the fastest growing malignancies in Taiwan, in addition to the two established risk factors, cigarette smoking and betel quid chewing.

METHODS

This is an observational study utilized the age-standardized incidence rates of oral cancer in the 316 townships and precincts of Taiwan, local prevalence rates of cigarette smoking and betel quid chewing, demographic factors, socio-economic conditions, and concentrations in farm soils of the eight kinds of heavy metal. Spatial regression and GIS (Geographic Information System) were used. The registration contained 22,083 patients, who were diagnosed with oral cancer between 1982 and 2002. The concentrations of metal in the soils were retrieved from a nation-wide survey in the 1980s.

RESULTS

The incidence rate of oral cancer is geographically related to the concentrations of arsenic and nickel in the patients' residential areas, with the prevalence of cigarette smoking and betel quid chewing as controlled variables.

CONCLUSIONS

Beside the two established risk factors, cigarette smoking and betel quid chewing, arsenic and nickel in farm soils may be new risk factors for oral cancer. These two kinds of metal may involve in the development of oral cancer. Further studies are required to understand the pathways via which metal in the farm soils exerts its effects on human health.

Survival after diagnosis of cancer of the oral cavity

In this retrospective study we analysed the survival in 470 patients with oral cancer. Patients who attended five university hospitals in Tehran, Iran, during the period 1996-2002 were included. Data were obtained from a combination of sources including patients' records, telephone calls, and deaths registered by the Ministry of Health. Survival curves were generated using Kaplan-Maier curves. Univariate and multivariate analyses of the relations between survival and age, sex, site of primary tumour, stage, and histopathological type were made using the log-rank test and Cox's regression analysis. Sex and age were not associated with survival. Treatment and stage of tumour at the time of diagnosis were related to survival. The overall survival rates were higher in patients with stages I or II cancer than those in stages III (OR=2.8, 95% CI=1.8 to 4.4) or IV (OR=4.6, 95% CI=3.1 to 6.8) at the time of diagnosis. Patients treated with radiotherapy had lower survival than those who had been operated on and had radiotherapy or operation alone (OR=2.8, 95% CI=1.7 to 4.5). There was no difference in survival depending on the histological type of tumour. To achieve higher survival, early detection and diagnosis of oral cancers should be emphasised in oral health programmes to improve public awareness and preventive activities among dentists in Iran.

Prognostic factors associated with the survival of oral and pharyngeal carcinoma in Taiwan

Background

In Taiwan, a distinct ethnic group variation in incidence and mortality rates has been suggested for most carcinomas. Our aim is to identify the role of prognostic factors associated with the survival of oral and pharyngeal carcinoma in Taiwan.

Methods

Taiwan Cancer Registry records of 9039 subjects diagnosed with oral and pharyngeal carcinoma were analyzed. The population was divided into three ethnic groups by residence, which were Taiwanese aborigines, Hakka and Hokkien communities. Five-year survival rates were estimated by Kaplan-Meier methods. Ethnic curves differed significantly by log-rank test; therefore separate models for Taiwanese aborigines, Hakka and Hokkien were carried out. The Cox multivariate proportional hazards model was used to examine the role of prognostic factors on ethnic survival.

Results

The five-year survival rates of oral and pharyngeal carcinoma were significantly poorer for Hokkien community (53.9%) and Taiwanese aborigines community (58.1%) compared with Hakka community (60.5%). The adjusted hazard ratio of Taiwanese aborigines versus Hakka was 1.07 (95%CI, 0.86–1.33) for oral and pharyngeal carcinoma mortality, and 1.16 (95%CI, 1.01–1.33) for Hokkien versus Hakka. Males had significantly poor prognosis than females. Subjects with tongue and/or mouth carcinoma presented the worst prognosis, whereas lip carcinoma had the best prognosis. Subjects with verrucous carcinoma had better survival than squamous cell carcinoma. Prognosis was the worst in elderly subjects, and subjects who underwent surgery had the highest survival rate.

Conclusion

Our study presented that predictive variables in oral and pharyngeal carcinoma survival have been: ethnic groups, period of diagnosis, gender, diagnostic age, anatomic site, morphologic type, and therapy.

Analysis of Death Certification in Patients With Early Stage Oral Cavity Squamous Cell Carcinoma

PURPOSE

Although patients with T1 oral cavity carcinoma have a generally good prognosis, there is a significant burden of patients that have locoregional recurrence and mortality from early stage disease. The aim of this study was to investigate the specific cause of death in patients with T1N0M0 oral cavity squamous cell carcinoma (OCSCC) by analysis of death certification.

PATIENTS AND METHODS

Patients were identified with T1 OCSCC treated over a 15-year period between 1986 to 2001 from the Mayo Clinic Tumor Registry. All patients were treated by operation without neck dissection or postoperative neoadjuvant therapy as the initial method of treatment. On detailed examination of the death certificate the leading cause of death was identified along with other clinical predictors of death.

RESULTS

Two hundred fifty patients were identified and met inclusion criteria from the Mayo Clinic Tumor Registry. Of the study group, 8.5% and 16% developed local and regional recurrence, respectively, as the first recurrence. The majority of recurrences that were amenable to surgery were managed by radical resection and postoperative neoadjuvant therapy. Of 85 deaths in the study group, 40 death certificates were obtained and reviewed to ascertain a specific cause of death. Patients were grouped into death from oral cancer, other cancer, or medical disease. Primary cause of death from the death certificates available for review included uncontrolled locoregional disease (20%), metastatic oral cancer (15%), development of secondary nonoral malignancy (15%), and a variety of medical causes (50%). Patient age at the time of diagnosis older than 65 had a statistically significant increase in mortality. Interestingly, the presence of premorbid medical conditions, history, or persistent tobacco and alcohol use did not seem to be related to overall mortality.

CONCLUSION

Early stage OCSCC continues to portend a poor prognosis. Analysis of death certification provides useful information of the specific cause of death.

Differential expression of E-cadherin in metastatic lesions comparing to primary oral squamous cell carcinoma

BACKGROUND

The main cause of treatment failure in resectable oral squamous cell carcinoma (OSCC) is metastasis. E-cadherin (E-cad) plays a principal role in cell adhesion and motility, and is associated with OSCC progression. The aim of this study was to investigate the clinical significance of E-cad expression in OSCC with lymph node metastasis which had radical neck dissection done.

METHOD

Immunohistochemistry was used to detect E-cad expression in normal oral mucosa (NOM) (n = 10), oral precancerous lesions (OPLs) (n = 20), primary OSCC (n = 45), and their paired metastatic lesions (n = 45). E-cad immunoreactivity correlated with the clinicopathologic features.

RESULTS

E-cadherin immunoreactivity was progressively reduced in the NOM followed by OPLs and primary OSCC (58%). It decreased significantly in the advanced stages of OSCC. However, the increase in E-cad immunoreactivity was observed in the majority (60%) of metastatic lesions in relation to primary OSCC. Patients with such increased or positive immunoreactivity of E-cad in metastatic lesions exhibited worse prognosis.

CONCLUSION

The findings suggested a dynamic change in E-cad immunoreactivity during tumorigenesis and metastasis of OSCC. In a multivariate analysis, E-cad immunoreactivity in metastasis lesions (odds ratio 3.74, 95% CI 1.15-14.67; P = 0.040) implied the potential role of mortality predictors for OSCC cases with nodal involvement.

Distinctive Features of Oral Cancer in Changhua County: High Incidence, Buccal Mucosa Preponderance, and a Close Relation to Betel Quid Chewing Habit

BACKGROUND/PURPOSE

Oral cancer is one of the fastest increasing malignancies in Taiwan. Among the counties on the island, Changhua has been ranked in the top three in the list of oral cancer incidence. This study was performed to better characterize the epidemiology of oral cancer in Changhua county.

METHODS

We used the complete registered records of oral cancer from the Department of Health databank, and studied the trends in incidence rate, age of distribution, and anatomic sites of oral cancer in Taiwan. In addition, we correlated the incidence rate with known risk factors (betel quid chewing, smoking, and alcohol drinking) by regression analysis.

RESULTS

Among neoplasms, oral cancer is one of the fastest increasing malignancies in Taiwan. In the past two decades from 1982 to 2001, Taiwan had an alarming 5.3-fold increase in the incidence of male oral cancer. Among the 23 counties, Changhua has ranked top in oral cancer incidence in recent years. The incidence of male oral cancer in Changhua is also among the highest in the world (45.07/105/year in 2001). The most common site was the buccal mucosa, while it was the tongue in other counties. Finally, Changhua was the only outlier in our regression model, indicating that possible interference factors may interact with oral cancer incidence and prevalence of betel quid chewing in Changhua.

CONCLUSION

We conclude that the high incidence and buccal mucosa preponderance of oral cancer in Changhua may have an exceptionally close relation with patients' betel quid chewing habit, and other unknown etiologic factors may also be present locally.

Toxic and metabolic effect of sodium butyrate on SAS tongue cancer cells: Role of cell cycle deregulation and redox changes

Butyrate is a metabolite produced by oral and colonic microorganism. Butyrate has been shown to reduce colon cancer, whereas its role in oral carcinogenesis is not clear. Butyrate concentration in dental plaque and saliva ranged from 0.2 to 16 mM. In this study, we found that sodium butyrate inhibited the growth of SAS tongue cancer cells by 32% and 53% at concentrations of 1 and 2mM, respectively. Low concentrations of sodium butyrate (1-8mM) induced G0/G1 cell cycle arrest of SAS cells, whereas concentrations of 4-16 mM elicited G2/M arrest and a slight increase in apoptotic cell populations. These events were concomitant with induction of intracellular reactive oxygen species (ROS) production. An elevation in p21 mRNA and protein level was noted in SAS cells by sodium butyrate. On the contrary, a decline of cyclin Bl, cdc2 and cdc25C mRNA and protein expression in SAS cells was found after exposure to sodium butyrate. In addition, no evident increase in cdc2 inhibitory phosphorylation was found in sodium butyrate-treated SAS cancer cells. Inclusion of N-acetyl-l-cysteine (NAC) (3mM), catalase (1000 U/ml) and dimethylthiourea (DMT, 5mM), and also SOD (500 U/ml) attenuated the sodium butyrate-induced ROS production in SAS cells. However, they were not able to prevent the cell cycle arrest, apoptosis and growth inhibition in SAS cells induced by 1, 2 and 16 mM of sodium butyrate. These results indicate that sodium butyrate is toxic and inhibits the tongue cancer cell growth via induction of cell cycle arrest and apoptosis. Sodium butyrate mediates these events by mechanisms additional to ROS production.

Increased NBS1 expression is a marker of aggressive head and neck cancer and overexpression of NBS1 contributes to transformation

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) represents the sixth most frequent type of cancer worldwide. However, the molecular genetic alterations underlying its malignant behavior and progression are little known. We showed previously that c-MYC directly activates the expression of the DNA double-strand break repair gene NBS1, and NBS1 overexpression contributes to transformation. Here, we investigate the role of NBS1 overexpression in HNSCC.

EXPERIMENTAL DESIGN

Immunohistochemistry analysis of NBS1 expression was done in 81 locally advanced HNSCC patients. Real-time PCR and Western blot analysis were used to confirm immunohistochemistry results. Human hypopharyngeal cancer cell lines (FADU) with overexpressing NBS1 (FADUNBS) or inducible short interference RNA to repress endogenous NBS1 (FADUNBSi) were generated by stable transfection. Soft agar clonogenicity assay was used to determine the transformation activity. Western blot analysis and phosphatidylinositol 3-kinase (PI3K) assay were done to evaluate the signaling pathways that were involved.

RESULTS

NBS1 overexpression was identified in 45% of advanced HNSCC patients. It was an independent marker of poor prognosis. NBS1 expression levels correlated with the transformation activity of FADU clones and also correlated with the phosphorylation levels of Akt and its downstream target mammalian target of rapamycin (mTOR). PI3K activity was increased in NBS1-overexpressing FADU clones. NBS1 overexpression also correlated with increased Akt phosphorylation levels in tumor samples.

CONCLUSIONS

Increased NBS1 expression is a significant prognostic marker of advanced HNSCC, and the underlying mechanism may involve the activation of the PI3K/Akt pathway.