Intratumor genetic heterogeneity and head and neck cancer relapse.

BACKGROUND: Head and neck squamous cell carcinomas are treated by surgery, radiotherapy (RT), chemoradiotherapy (CRT) or combinations thereof, but locoregional recurrences (LRs) occur in 30-40% of treated patients. We have previously shown that in approximately half of the LRs after CRT, cancer driver mutations are not shared with the index tumor. AIM: To investigate two possible explanations for these genetically unrelated relapses, treatment-induced genetic changes and intratumor genetic heterogeneity. METHODS: To investigate treatment-induced clonal DNA changes, we compared copy number alterations (CNAs) and mutations between primary and recurrent xenografted tumors after treatment with (C)RT. Intratumor genetic heterogeneity was studied by multi-region sequencing on DNA from 31 biopsies of 11 surgically treated tumors. RESULTS: Induction of clonal DNA changes by (C)RT was not observed in the xenograft models. Multi-region sequencing demonstrated variations in CNA profiles between paired biopsies of individual tumors, with copy number heterogeneity scores varying from 0.027 to 0.333. In total, 32 cancer driver mutations could be identified and were shared in all biopsies of each tumor. Remarkably, multi-clonal mutations in these same cancer driver genes were observed in 6 of 11 tumors. Genetically distinct heterogeneous cell cultures could also be established from single tumors, with different biomarker profiles and drug sensitivities. CONCLUSION: Intratumor genetic heterogeneity at the level of the cancer driver mutations might explain the discordant mutational profiles in LRs after CRT, while there are no indications in xenograft models that these changes are induced by CRT.

[Identification of differentiated dysplasia improves prediction of oral leukoplakia at increased risk of malignant progression]. / Onderkenning van gedifferentieerde dysplasie voor het voorspellen van de kans op maligne ontaarding van orale leukoplakie.

Oral leukoplakia is the most common potentially malignant disorder of the oral mucosa with a rate of malignant transformation into oral squamous cell carcinoma of 1-2% annually. The presence or absence of dysplasia as defined by the WHO is an important histological marker for malignant transformation risk assessment, but is not sufficiently accurate for patient stratification. We investigated whether identifying differentiated dysplasia contributes to oral leukoplakia malignant transformation risk assessment. We investigated whether classic or differentiated dysplasia were present in 84 oral leukoplakias. In 25 of these patients a squamous cell carcinoma developed during follow-up. Risk of malignant progression of oral leukoplakia increased from 3.3 (HR, p = 0.002) when only classic dysplasia was considered to 7.4 (HR, p = 0.001) when both classic and differentiated dysplasia were combined. This study demonstrates that identifying differentiated dysplasia as a separate type of dysplasia is important for the prognosis and stratification of patients with oral leukoplakia.

Correction to: Advancing interdisciplinary research in head and neck cancer through a multicenter longitudinal prospective cohort study: the NETherlands QUality of life and BIomedical Cohort (NET-QUBIC) data warehouse and biobank.

Following publication of the original article [1], the authors reported the name of R.J. Baatenburg de Jong was incorrectly tagged in the HTML version of the article.

Advancing interdisciplinary research in head and neck cancer through a multicenter longitudinal prospective cohort study: the NETherlands QUality of life and BIomedical Cohort (NET-QUBIC) data warehouse and biobank.

BACKGROUND: Worldwide, over 500,000 people are diagnosed with head and neck cancer each year, a disease with major impact on life expectancy and quality of life. The purpose of the Netherlands Quality of life and Biomedical Cohort study (NET-QUBIC) is to advance interdisciplinary research that aims to optimize diagnosis, treatment, and supportive care for head and neck cancer patients and their informal caregivers. METHODS: Using an extensive assessment protocol (electronic clinical record form, patient reported outcome measures and fieldwork (interviews and physical tests)), clinical data and data on quality of life, demographic and personal factors, psychosocial (depression, anxiety, fatigue, pain, sleep, mental adjustment to cancer, posttraumatic stress), physical (speech, swallowing, oral function, malnutrition, physical fitness, neurocognitive function, sexual function), lifestyle (physical activity, nutrition, smoking, alcohol, drugs), and social factors (social function, social support, work, health care use, and costs) are collected and stored in the data warehouse. A longitudinal biobank is built with tumor tissue, blood and blood components, saliva samples, and oral rinses. An infrastructure for fieldwork and laboratory protocols is established at all participating centers. All patients fill out patient reported outcome measures before treatment and at 3, 6, 12, 24, 36, 48, and 60 months follow-up. The interviews, physical tests and biological sample collection are at baseline and 6, 12, and 24 months follow-up. The protocol for caregivers includes blood sampling and oral rinses at baseline and a tailored list of questionnaires, administered at the same time points as the patients. In total, 739 HNC patients and 262 informal caregivers have been included in 5 out of the 8 HNC centers in the Netherlands. DISCUSSION: By granting access to researchers to the NET-QUBIC data warehouse and biobank, we enable new research lines in clinical (e.g. treatment optimization in elderly patients), biological (e.g. liquid biopsy analysis for relapse detection), health related quality of life (e.g. the impact of toxicity on quality of life), and interrelated research (e.g. health related quality of life in relation to biomarkers and survival).

Evaluation of the eighth TNM classification on p16-positive oropharyngeal squamous cell carcinomas in the Netherlands and the importance of additional HPV DNA testing.

Background: Oropharyngeal squamous cell carcinomas (OPSCCs) are traditionally caused by smoking and excessive alcohol consumption. However, in the last decades high-risk human papillomavirus (HPV) infections play an increasingly important role in tumorigenesis. HPV-driven OPSCCs are known to have a more favorable prognosis, which has led to important and marked changes in the recently released TNM-8. In this 8th edition, OPSCCs are divided based on p16 immunostaining, with p16 overexpression as surrogate marker for the presence of HPV. The aims of this study are to evaluate TNM-8 on a Dutch consecutive cohort of patients with p16-positive OPSCC and to determine the relevance of additional HPV DNA testing. Patients and methods: All OPSCC patients without distant metastases at diagnosis and treated with curative intent at VU University Medical Center (2000-2015) and Erasmus Medical Center (2000-2006) were included (N = 1204). HPV status was determined by p16 immunostaining followed by HPV DNA PCR on the p16-immunopositive cases. We compared TNM-7 and TNM-8 using the Harrell's C index. Results: In total, 388 of 1204 (32.2%) patients were p16-immunopositive. In these patients, TNM-8 had a markedly better predictive prognostic power than TNM-7 (Harrell's C index 0.63 versus 0.53). Of the 388 p16-positive OPSCCs, 48 tumors (12.4%) were HPV DNA-negative. This subgroup had distinct demographic, clinical and morphologic characteristics and showed a significantly worse five-year overall survival compared with the HPV DNA-positive tumors (P < 0.001). Conclusions: TNM-8 has a better predictive prognostic power than TNM-7 in patients with p16-positive OPSCC. However, within p16-positive OPSCCs, there is an HPV DNA-negative subgroup with distinct features and a worse overall survival, indicating the importance to perform additional HPV DNA testing when predicting prognosis and particularly for selecting patients for de-intensified treatment regimens.

Epidemiologic associations of HPV-positive oropharyngeal cancer and (pre)cancerous cervical lesions.

Human papillomavirus (HPV)-induced oropharyngeal squamous cell carcinoma (OPSCC) remains increasing worldwide. We aimed to investigate if the HPV-prevalence of OPSCC in the Netherlands is rising as well, also in female patients. In addition, we evaluated the association between HPV-positive OPSCC and suspicious Pap results of the cervix in these female patients. Patients with OPSCC treated in the period 2000-2015 at the VU University Medical Center Amsterdam, were included (n = 926). The presence of an oncogenic HPV infection was determined by p16-immunostaining, followed by a high-risk HPV general primer 5+/6+ DNA PCR on the p16-immunopositive cases. A review of pathology reports in all female patients (n = 305) was undertaken to identify cytological signs of HPV-related (pre)cancer of the cervix. In total 281 of 926 (30.3%) OPSCCs were HPV-positive. Moreover, a significant increase in the prevalence of HPV-positive OPSCCs was observed from 14.0% in 2000 to 48.1% in 2015 (p < 0.001). Among the female patients with an HPV-positive OPSSC (n = 70), the results of cervical smears were available in 56 of 70 patients (80.0%). Of the female patients with HPV-positive OPSCC, 9 of 56 (16.1%) patients had a vaginal cuff Papanicolaou (Pap) test ≥3b in their medical history compared to 7 of 168 (4.2%) in the HPV-negative group (p = 0.003). In conclusion, a continuous increase in the HPV-attributable fraction of OPSCC was demonstrated in the period 2000-2015 in the Amsterdam region. HPV-positive OPSCC has a significant association with a history of suspicious Pap results of the cervix in female patients.

Moving towards personalised therapy in head and neck squamous cell carcinoma through analysis of next generation sequencing data.

Personalised medicine tumour boards, which leverage genomic data to improve clinical management, are becoming standard for the treatment of many cancers. This paper is designed as a primer to assist clinicians treating head and neck squamous cell carcinoma (HNSCC) patients with an understanding of the discovery and functional impact of recurrent genetic lesions that are likely to influence the management of this disease in the near future. This manuscript integrates genetic data from publicly available array comparative genome hybridization (aCGH) and next-generation sequencing genetics databases to identify the most common molecular alterations in HNSCC. The importance of these genetic discoveries is reviewed and how they may be incorporated into clinical care decisions is discussed. Considerations for the role of genetic stratification in the clinical management of head and neck cancer are maturing rapidly and can be improved by integrating data sets. This article is meant to summarise the discoveries made using multiple genomic platforms so that the head and neck cancer care provider can apply these discoveries to improve clinical care.

Different prognostic models for different patient populations: validation of a new prognostic model for patients with oropharyngeal cancer in Western Europe.

OBJECTIVE: The presence of human papillomavirus (HPV) infection in oropharyngeal squamous cell carcinoma (OPSCC) is a major determinant in prognostic risk modelling. Recently, a prognostic model was proposed in which HPV status, comorbidity and nodal stage were the most important prognostic factors to determine high-, intermediate- and low-risk survival groups. Here, we report on the validation of this model using an independent single-institutional cohort. METHODS: A total number of 235 patients curatively treated for OPSCC in the period 2000-2011 at the MUMC (Maastricht University Medical Center, The Netherlands) were included. The presence of an oncogenic HPV infection was determined by p16 immunostaining, followed by a high-risk HPV DNA PCR on the p16-positive cases. The model variables included were HPV status, comorbidity and nodal stage. As a measure of model performance, the Harrell's Concordance index (Harrell's C-index) was used. RESULTS: The 5-year overall survival (OS) estimates were 84.6%, 54.5% and 28.7% in the low-, intermediate- and high-risk group, respectively. The difference between the survival curves was highly significant (P<0.001). The Harrell's C-index was 0.69 (95% confidence interval (CI): 0.63-0.75). CONCLUSION: In this study a previously developed prognostic risk model was validated. This model will help to personalise treatment in OPSCC patients. This model is publicly available at www.predictcancer.org.

Quantitative diffusion-weighted MRI parameters and human papillomavirus status in oropharyngeal squamous cell carcinoma.

BACKGROUND AND PURPOSE: Patients with human papillomavirus-positive oropharyngeal squamous cell carcinomas have a better survival rate than those with human papillomavirus-negative oropharyngeal squamous cell carcinomas. DWI characterizes biologically relevant tumor features, and the generated ADC may also provide prognostic information. We explored whether human papillomavirus status and ADC values are independent tumor characteristics. MATERIALS AND METHODS: Forty-four patients with oropharyngeal squamous cell carcinomas underwent pretreatment DWI. ADC values for the primary tumors were determined by using 3 b-values in an ROI containing the largest area of solid tumor on a single section of an axial DWI image. Human papillomavirus status was determined with p16 immunostaining, followed by high-risk human papillomavirus DNA detection on the p16-positive cases. RESULTS: Twenty-two patients were human papillomavirus-positive (50.0%). ADC values were not significantly different between human papillomavirus-negative (ADC(mean) = 1.56 [1.18-2.18] × 10(3) mm(2)/s) and human papillomavirus-positive tumors (ADC(mean) = 1.46 [1.07-2.16] × 10(3) mm(2)/s). CONCLUSIONS: No significant association between ADC and human papillomavirus status was found in oropharyngeal squamous cell carcinomas. In our study population, differences in genetic and histologic features between human papillomavirus-positive and human papillomavirus-negative oropharyngeal squamous cell carcinomas did not translate into different ADC values. Long-term follow-up studies are needed to establish whether ADC has prognostic value and whether this is independent of the human papillomavirus status.

TP53 mutation and human papilloma virus status of oral squamous cell carcinomas in young adult patients.

OBJECTIVE: Little is known about the molecular carcinogenesis of oral squamous cell carcinoma (OSCC) in young adult patients. The aim of this study was to investigate the detailed TP53 mutation and human papilloma virus (HPV) status of OSCC in patients, younger than 45 years. METHODS: TP53 mutations were determined with direct sequencing on paraffin-embedded carcinoma tissue from 31 young patients and compared with two older age OSCC reference groups: one from the same institute (N = 87) and an independent one (N = 675). Biologically active tumour HPV was detected by p16-immunohistochemistry followed by a HPV-DNA GP5 + /6 + -PCR. RESULTS: HPV16 was present in one OSCC (3%). TP53 mutations were found in 14 (45%) OSCC: five were missense and nine resulted in a truncated protein. Six of these latter were insertions or deletions of one or more nucleotides leading to frameshift, one was at a splice site and two resulted in a stop codon. The percentage of truncating mutations (64% of all mutations) was higher than that observed in the institute's reference group (44%, P = 0.23) and in the independent reference group (24%, P = 0.002). CONCLUSIONS: This study shows that TP53 mutations are common in OSCC of young adult patients; infection with biologically active HPV is rare.

Human papillomavirus detection and comorbidity: critical issues in selection of patients with oropharyngeal cancer for treatment De-escalation trials.

BACKGROUND: The presence of human papillomavirus (HPV)-infection in oropharyngeal squamous cell carcinoma (OPSCC) is a major determinant in prognostic risk modeling. However, most risk models are based on clinical trials which only include a selected patient population. The clinical significance of HPV and other prognostic factors in patients with OPSCC remains to be evaluated in a large, unselected cohort, which also includes patients with stage I/II disease and patients with severe comorbidity. PATIENTS AND METHODS: All patients diagnosed with OPSCC in 2000-2006 in two Dutch university hospitals were included. The presence of an oncogenic HPV infection was determined by p16-immunostaining, followed by a high-risk HPV general primer 5+/6+ DNA PCR on the p16-positive cases. Cox regression analysis was carried out to compare survival rates between HPV-positive and HPV-negative patients and a prognostic model was generated by recursive partitioning. RESULTS: In total, 163 of 841 (19.4%) tumors were HPV-positive. Patients with HPV-positive OPSCC had a more favorable overall survival [73.5% versus 40.9% after 5 years; P < 0.001; hazard ratio = 0.34, 95% confidence interval (CI) 0.25-0.48] compared with patients with HPV-negative OPSCC. Patients with p16-positive but HPV DNA-negative tumors showed a significantly less favorable survival than patients with p16-positive and HPV DNA-positive tumors (P < 0.001). A prognostic model was developed in which patients were classified into three risk groups according to HPV status, nodal stage and comorbidity. [Harrell's concordance index of 0.68 (95% CI 0.65-0.71)]. CONCLUSIONS: Tumor HPV status is a strong and independent prognostic factor for survival among patients with OPSCC. A prognostic risk model was proposed, based on our large, unselected cohort of patients with HPV status, comorbidity and nodal stage being the important prognostic factors. In addition, this study emphasizes the importance of performing an HPV DNA-specific test besides p16-immunostaining.

Expression signature in peripheral blood cells for molecular diagnosis of head and neck squamous cell carcinoma.

Patients with head and neck squamous cell carcinoma (HNSCC) have a poor prognosis due to the development of locoregional recurrences, distant metastases, and second primary tumors. There is an urgent need for biomarkers that enable detection and monitoring of the disease to provide adequate therapeutic strategies. In this study, we have investigated markers in peripheral blood cells (PBC) of 28 HNSCC patients who underwent surgery by means of expression profiling. Our hypothesis is that nucleated blood cells circulate continuously, also pass the tumor, and change their expression profile in response to tumor cell factors. For comparison, we enrolled a control group of 11 patients who underwent surgery in the head and neck region for non-HNSCC reasons. A set of 2949 genes was found to be statistically different between the groups (P < 0.05, false discovery rate-corrected) and the most prominently different pathways were EIF2, EIF4, and mTOR signaling. These preliminary results are promising and warrant further studies on the definitive role of PBC gene expression as a biomarker for HNSCC detection and monitoring.

Treatment choice for locally advanced head and neck cancers on the basis of risk factors: biological risk factors.

Patients with locally advanced head and neck squamous cell carcinoma often experience relapse, the cause of poor survival statistics. Relapse occurs following the three main types of treatment, surgery with or without post-operative (chemo)radiotherapy, or chemoradiation (containing cisplatin). Cancer relapse can result from (i) outgrowth of residual tumour cells, sometimes with a number too small to be detected by routine histopathology or (ii) development of another carcinoma in a field of pre-neoplastic cells that has remained after treatment of the primary carcinoma. At this moment, clinical staging is not enough to identify patients who will develop relapse and who need tailored treatment. This review describes the latest knowledge of mechanisms of cancer relapse, addresses the biomarkers of potential interest detectable in the tissue of the tumour or its surgical margins and discusses three biomarkers, human papillomavirus, TP53 and epidermal growth receptor in more detail. Once a marker panel has been established, treatment should be focussed on the patients at risk of relapse by improved tailoring of existing treatment modalities. Also, the implementation of more targeting therapies based on the characteristics of the discovered markers should lead to better survival rates.

Comparison of oncolytic adenoviruses for selective eradication of oral cancer and pre-cancerous lesions.

Oncolytic adenoviruses are being investigated as potential anti-cancer agents. Selective lytic replication in cancer cells is essential for an effective and safe treatment. In this study, we compared 11 oncolytic adenoviruses in relevant cell cultures to assess their use for treating oral cancer and pre-cancerous lesions. We determined the cytotoxicity of oncolytic adenovirus infection and calculated selectivity indices for cytotoxicity to cancer cells compared with normal oral keratinocytes and fibroblasts. Keratinocytes were very sensitive to wild-type adenovirus serotype 5 (Ad5); 1- to 3-log more than head and neck squamous cell carcinoma (HNSCC) cells. The potencies of oncolytic adenoviruses to kill HNSCC cells within 7 days after infection ranged from approximately 10 times less potent to approximately 10 times more potent than Ad5. The selectivity indices determined on fibroblasts and keratinocytes differed markedly. Two oncolytic adenoviruses were more selective than Ad5 for HNSCC cells compared with fibroblasts; and five viruses showed selective replication on HNSCC cells compared with keratinocytes. Overall, CRAd-S.RGD with E1A driven by the survivin promoter and an infectivity-enhancing capsid modification showed the most favourable cytotoxicity pattern; being very potent in killing HNSCC cells, only slightly less effective than Ad5 in killing pre-neoplastic keratinocytes and the least toxic to normal keratinocytes.

Differential diagnosis of pulmonary carcinoma following head and neck cancer by genetic analysis.

PURPOSE: Patients with head and neck cancer often develop a lung tumor that can be diagnosed as distant metastasis (DM) or second primary tumor (SPT). In this study, we use TP53 mutation analysis for validation of an allelic loss marker panel and a decision algorithm for distinguishing between DM and SPT. EXPERIMENTAL DESIGN: Tumor pairs of 39 patients were analyzed for TP53 mutations, for patterns of allelic loss and immunohistochemical analysis of p53 expression. Results of these three analyses were compared, using mutation analysis as gold standard. RESULTS: Loss of heterozygosity (LOH) analysis indicated DM in 15 and SPT in 23 cases (one inconclusive). TP53 mutation analysis was informative in 15 cases. Based on the p53 mutation status alone, nine tumors were diagnosed as SPT and six as DM. In all 15 cases the LOH analysis was in concordance with the TP53 mutation analysis. Immunostaining for p53 showed promise as a first scan to diagnose lung tumors as SPT but cannot be used to diagnose DM. CONCLUSION: The TP53 mutation data validate the suitability of the LOH marker panel and decision algorithm for differential diagnosis of DM and SPT in the lung. LOH analysis can theoretically be exploited in almost all cases and is less laborious than TP53 mutation analysis.

Changes in the status of p53 affect drug sensitivity to thymidylate synthase (TS) inhibitors by altering TS levels.

Colorectal cancer (CRC) resistance to fluoropyrimidines and other inhibitors of thymidylate synthase (TS) is a serious clinical problem often associated with increased intracellular levels of TS. Since the tumour suppressor gene p53, which is mutated in 50% of CRC, regulates the expression of several genes, it may modulate TS activity, and changes in the status of p53 might be responsible for chemoresistance. Therefore, this study was aimed to investigate TS levels and sensitivity to TS inhibitors in wild-type (wt) and mutant (mt) p53 CRC cells, Lovo and WiDr, respectively, transfected with mt and wt p53. Lovo 175X2 cells (transfected with mt p53) were more resistant to 5-fluorouracil (5-FU; 2-fold), nolatrexed (3-fold), raltitrexed (3-fold) and pemetrexed (10-fold) in comparison with the wt p53 parental cells Lovo 92. Resistance was associated with an increase in TS protein expression and catalytic activity, which might be caused by the loss of the inhibitory effect on the activity of TS promoter or by the lack of TS mRNA degradation, as suggested by the reversal of TS expression to the levels of Lovo 92 cells by adding actinomycin. In contrast, Lovo li cells, characterized by functionally inactive p53, were 3-13-fold more sensitive to nolatrexed, raltitrexed and pemetrexed, and had a lower TS mRNA, protein expression and catalytic activity than Lovo 92. However, MDM-2 expression was significantly higher in Lovo li, while no significant differences were observed in Lovo 175X2 cells with respect to Lovo 92. Finally, mt p53 WiDr transfected with wt p53 were not significantly different from mt p53 WiDr cells with respect to sensitivity to TS inhibitors or TS levels. Altogether, these results indicate that changes in the status of p53, can differently alter sensitivity to TS inhibitors by affecting TS levels, depending on activity or cell line, and might explain the lack of clear correlation between mutations in p53 and clinical outcome after chemotherapy with TS inhibitors.

Expression profiling and prediction of distant metastases in head and neck squamous cell carcinoma.

BACKGROUND: For breast and prostate cancer, a gene expression signature of the tumour is associated with the development of distant metastases. Regarding head and neck squamous cell carcinoma (HNSCC), the only known risk factor is the presence of > or =3 tumour-positive lymph nodes. AIM: To evaluate whether a HNSCC gene expression signature can discriminate between the patients with and without distant metastases. METHODS: Patients with HNSCC with and without distant metastases had >3 tumour-positive lymph nodes, and did not differ with respect to other risk factors. Statistical analysis was carried out using Student's t test, as well as statistical analysis of microarrays (SAM), to assess the false discovery rate for each gene. These analyses were supplemented with a newly developed method that computed deviations from gaussian-order statistics (DEGOS). To validate the platform, normal mucosa of the head and neck was included as control. RESULTS: 2963 genes were differently expressed between HNSCC and normal mucosa (t test; p<0.01). More rigorous statistical analysis with SAM confirmed the differential expression of most genes. The comparison of genes in HNSCC with and without metastases showed 150 differently expressed genes (t test; p<0.01), none of which, however, could be confirmed using SAM or DEGOS. CONCLUSIONS: No evidence for a metastasis signature is found, and gene expression profiling of HNSCC has seemingly no value in determining the risk of developing distant metastases. The absence of such a signature can be understood when it is realised that, for HNSCC in contrast with breast cancer, the lymph nodes are a necessary in-between station for haematogenous spread.

Genome-wide DNA copy number alterations in head and neck squamous cell carcinomas with or without oncogene-expressing human papillomavirus.

Oncogene-expressing human papillomavirus type 16 (HPV16) is found in a subset of head and neck squamous cell carcinomas (HNSCC). HPV16 drives carcinogenesis by inactivating p53 and pRb with the viral oncoproteins E6 and E7, paralleled by a low level of mutations in TP53 and allelic loss at 3p, 9p, and 17p, genetic changes frequently found in HNSCCs of nonviral etiology. We hypothesize that two pathways to HNSCC exist: one determined by HPV16 and the other by environmental carcinogens. To define the critical genetic events in these two pathways, we now present a detailed genome analysis of HNSCC with and without HPV16 involvement by employing high-resolution microarray comparative genomic hybridization. Four regions showed alterations in HPV-negative tumors that were absent in HPV-positive tumors: losses at 3p11.2-26.3, 5q11.2-35.2, and 9p21.1-24, and gains/amplifications at 11q12.1-13.4. Also, HPV16-negative tumors demonstrated loss at 18q12.1-23, in contrast to gain in HPV16-positive tumors. Seven regions were altered at high frequency (>33%) in both groups: gains at 3q22.2-qter, 5p15.2-pter, 8p11.2-qter, 9q22-34.1, and 20p-20q, and losses at 11q14.1-qter and 13q11-33. These data show that HNSCC arising by environmental carcinogens are characterized by genetic alterations that differ from those observed in HPV16-induced HNSCC, and most likely occur early in carcinogenesis. A number of genetic changes are shared in both tumor groups and can be considered crucial in the later stages of HNSCC progression.

Thymidylate synthase inhibition triggers apoptosis via caspases-8 and -9 in both wild-type and mutant p53 colon cancer cell lines.

Thymidylate synthase (TS) is an important target for chemotherapy and increased levels are associated with resistance to colorectal cancer chemotherapy. TS can be inhibited by 5-fluorouracil (5-FU) and antifolates, ultimately resulting in apoptosis. We aimed to clarify whether activation of caspases and Fas signalling are crucial for the onset of apoptosis after specific inhibition of TS and whether p53 plays a role in activation of these downstream processes. For this purpose, wild-type (wt) and mutant (mt) p53 colon cancer cell lines, Lovo and WiDr, respectively, transfected with mt- and wt-p53, were treated with the specific TS inhibitor, AG337. Treatment with 10xIC(50) values of AG337 for 48 h resulted in S phase arrest in all Lovo and WiDr cells (up to 50% of cells being in S phase), irrespective of their p53 status. After 72 h, the induction of apoptosis was most pronounced in the AG337-sensitive cells. Approximately 30% apoptosis was detected in all of the WiDr cells, 20% in Lovo li (non-functional p53), 12-14% in Lovo 92 and B2 (wt p53) and only 7% in Lovo 175x2 cells (mt p53 transfected). The induction of apoptosis in Lovo cells, as determined using the classical sub-G1 peak after propidium iodide (PI) staining, was associated with an increase in the expression of Fas receptor. In addition, synergistic increases in apoptosis from approximately 10 to 35% after 48 h could be detected after simultaneous treatment of AG337 and the Fas activator antibody, CH11. Only additive effects were measurable in WiDr cells, without an increase in Fas receptor expression. Surprisingly, the Fas inhibitor, ZB4, could not decrease the amount of cell death in both cell lines after AG337 treatment. In contrast, simultaneous exposure of Lovo and WiDr cells to AG337 and inhibitors of caspases 8, 9 and 3 caused a decrease in the number of apoptotic cells compared with AG337 exposure alone. Inhibition of apoptosis by approximately 10-80% in Lovo and approximately 70-80% in WiDr cells could be detected. In conclusion, these results indicate that apoptosis induced after specific inhibition of TS is mediated via the caspases, but without clear involvement of Fas signalling. The status of p53 did not affect the onset of apoptosis by these caspases.