Cytology vs molecular analysis for the detection of head and neck squamous cell carcinoma in oesopharyngeal brush samples: a prospective study in 56 patients

Analysis of microsatellite mutations in buccal cells from a case-control study for lung cancer

Exposure to tobacco carcinogens is the major cause of human lung cancer, but even heavy smokers have only about a 10% life-time risk of developing lung cancer. Currently used screening processes, based largely on age and exposure status, have proven to be of limited clinical utility in predicting cancer risk. More precise methods of assessing an individual's risk of developing lung cancer are needed. Because of their sensitivity to DNA damage, microsatellites are potentially useful for the assessment of somatic mutational load in normal cells. We assessed mutational load using hypermutable microsatellites in buccal cells obtained from lung carcinoma cases and controls to test if such a measure could be used to estimate lung cancer risk. There was no significant association between smoking status and mutation frequency with any of the markers tested. No significant association between case status and mutation frequency was observed. Age was significantly related to mutation frequency in the microsatellite marker D7S1482. These observations indicate that somatic mutational load, as measured using mutation frequency of microsatellites in buccal cells, increases with increasing age but that subjects who develop lung cancer have a similar mutational load as those who remain cancer free. This finding suggests that mutation frequency of microsatellite mutations in buccal cells may not be a promising biomarker for lung cancer risk.

Clinical relevance of nine transcriptional molecular markers for the diagnosis of head and neck squamous cell carcinoma in tissue and saliva rinse

BACKGROUND

Analysis of 23 published transcriptome studies allowed us to identify nine genes displaying frequent alterations in HNSCC (FN1, MMP1, PLAU, SPARC, IL1RN, KRT4, KRT13, MAL, and TGM3). We aimed to independently confirm these dysregulations and to identify potential relationships with clinical data for diagnostic, staging and prognostic purposes either at the tissue level or in saliva rinse.

METHODS

For a period of two years, we systematically collected tumor tissue, normal matched mucosa and saliva of patients diagnosed with primary untreated HNSCC. Expression levels of the nine genes of interest were measured by RT-qPCR in tumor and healthy matched mucosa from 46 patients. MMP1 expression level was measured by RT-qPCR in the salivary rinse of 51 HNSCC patients and 18 control cases.

RESULTS

Dysregulation of the nine genes was confirmed by the Wilcoxon test. IL1RN, MAL and MMP1 were the most efficient diagnostic markers of HNSCC, with ROC AUC > 0.95 and both sensitivity and specificity above 91%. No clinically relevant correlation was found between gene expression level in tumor and T stage, N stage, tumor grade, global survival or disease-free survival. Our preliminary results suggests that with 100% specificity, MMP1 detection in saliva rinse is potentially useful for non invasive diagnosis of HNSCC of the oral cavity or oropharynx, but technical improvement is needed since sensitivity was only 20%.

CONCLUSION

IL1RN, MAL and MMP1 are prospective tumor diagnostic markers for HNSCC. MMP1 overexpression is the most promising marker, and its detection could help identify tumor cells in tissue or saliva.

Mitochondria As A Target For Early Detection and Diagnosis of Cancer

Mitochondrial dysfunction and mutations in mitochondrial DNA (mtDNA) have been frequently reported in cancer, neurodegenerative diseases, diabetes, and aging syndromes. The mitochondrion genome (16.5 Kb) codes only for a small fraction (estimated to be 1%) of the proteins housed within this organelle. The other proteins are encoded by the nuclear DNA (nDNA) and transported into the mitochondria. The identification of mitochondrial proteins that are aberrantly expressed in cancer cells and other diseases is now possible through recent developments in proteomic and bioinformatic technologies. These developments set the stage for a comprehensive organelle-based proteomic approach for the identification of new markers for the early detection, risk assessment, and diagnosis of cancer, and other diseases and for the identification of new targets for therapeutic prevention and intervention.

Microsatellite mutations in buccal cells are associated with aging and head and neck carcinoma

Carcinogen exposure from tobacco smoking is the major cause of upper aerodigestive tract cancer, yet heavy smokers only have about a 10% life-time risk of developing one of these cancers. Current technologies allow only limited prediction of cancer risk and there are no approved screening methods applicable to the general population. We developed a method to assess somatic mutational load using small-pool PCR (SP-PCR) and analysed mutations in DNA isolated from cells obtained by mouth rinse. Mutation levels in the hypermutable tetranucleotide marker D7S1482 were analysed in specimens from 25 head and neck squamous carcinoma (HNSCC) cases and 31 controls and tested for associations with age, smoking history and cancer status. We found a significant association between mutation frequency and age (P=0.021, Generalized Linear Model (GLM), N=56), but no influence of smoking history. Cases had higher mutation frequencies than controls when corrected for the effects of age, a difference that was statistically significant in the subgroup of 10 HNSCC patients who were treated with surgery only (P=0.017, GLM, N=41). We also present evidence that cancer status is linked to levels of nonunique, and presumably clonally derived, mutations in D7S1482. Insertion mutations were observed in 833 (79%) of 1058 alleles, of which 457 (43%) could be explained by insertion of a single repeat unit; deletion mutations were found in 225 (21%) of tested alleles. In conclusion, we demonstrate that the sensitive detection of single molecule mutations in clinical specimens is feasible by SP-PCR. Our study confirms an earlier report that microsatellite mutations increase with age and is the first to provide evidence that these mutations may be associated with cancer status in individual subjects.

Mutagenic effect of cadmium on tetranucleotide repeats in human cells

Cadmium is a human carcinogen that affects cell proliferation, apoptosis and DNA repair processes that are all important to carcinogenesis. We previously demonstrated that cadmium inhibits DNA mismatch repair (MMR) in yeast cells and in human cell-free extracts (H.W. Jin, A.B. Clark, R.J.C. Slebos, H. Al-Refai, J.A. Taylor, T.A. Kunkel, M.A. Resnick, D.A. Gordenin, Cadmium is a mutagen that acts by inhibiting mismatch repair, Nat. Genet. 34 (3) (2003) 326-329), but cadmium also inhibits DNA excision repair. For this study, we selected a panel of three hypermutable tetranucleotide markers (MycL1, D7S1482 and DXS981) and studied their suitability as readout for the mutagenic effects of cadmium. We used a clonal derivative of the human fibrosarcoma cell line HT1080 to assess mutation levels in microsatellites after cadmium and/or N-methyl-N-nitro-N-nitrosoguanidine (MNNG) exposure to study effects of cadmium in the presence or absence of base damage. Mutations were measured in clonally expanded cells obtained by limiting dilution after exposure to zero dose, 0.5 microM cadmium, 5 nM MNNG or a combination of 0.5 microM cadmium and 5 nM MNNG. Exposure of HT1080-C1 to cadmium led to statistically significant increases in microsatellite mutations, either with or without concurrent exposure to MNNG. A majority of the observed mutant molecules involved 4-nucleotide shifts consistent with DNA slippage mutations that are normally repaired by MMR. These results provide evidence for the mutagenic effects of low, environmentally relevant levels of cadmium in intact human cells and suggest that inhibition of DNA repair is involved.

Molecular Detection of Early-Stage Laryngopharyngeal Squamous Cell Carcinomas

PURPOSE

We sought to determine whether early-stage laryngopharyngeal squamous cell carcinomas (SCC) can be detected through molecular analysis of exfoliated cells collected with the use of a pharyngoesophageal brush (PEB).

EXPERIMENTAL DESIGN

Thirty-three patients with a single, untreated, early-stage (T1 or T2) SCC of the supraglottic larynx or pharynx underwent collection of cells with a PEB, followed by endoscopic biopsy of the tumor. PEB specimens were also collected from five healthy subjects. PEB samples and tumor tissue were examined for hypermethylation of p16INK4a (CDKN2) gene promoter CpG islands (assayed by methylation-specific PCR) and UT5085 tetranucleotide microsatellite instability (assayed by GeneScan analysis). PEB samples were also subjected to cytologic analysis.

RESULTS

Eight of 33 (24%) tumors exhibited a bandshift at UT5085, and 14 of 33 (42%) exhibited hypermethylation at the p16 promoter. Overall, 17 of 33 (52%) patients had at least one of the two markers in their tumor. Cytologic analysis of PEB samples revealed tumor in 4 of 33 (12%) patients; cytologic findings were normal in all five control subjects. Molecular analysis of PEB samples revealed tumor DNA in 13 of 17 (76%) patients with at least one of the two molecular markers in their tumor. Eight of 14 (57%) patients with p16 hypermethylation in their tumor and 8 of 8 (100%) patients with UT5085 microsatellite instability in their tumor had similar findings in the PEB samples. None of the PEB samples from the control subjects or patients with neither molecular marker in their tumor displayed abnormality.

CONCLUSION

Molecular analysis of PEB samples holds promise for the early detection of early-stage laryngopharyngeal SCCs. New molecular markers need to be identified to increase the sensitivity of molecular screening.

Tetranucleotide microsatellite instability in surgical margins for prediction of local recurrence of head and neck squamous cell carcinoma

PURPOSE

Postoperative radiotherapy is used to prevent local recurrence of head and neck squamous cell carcinoma in patients with positive surgical margins. We sought to determine whether tetranucleotide microsatellite instability could be detected in surgical margins and used to predict local recurrence.

EXPERIMENTAL DESIGN

We prospectively collected tumor and surgical margin specimens from patients with head and neck squamous cell carcinoma who had undergone surgical resection at Institut Gustave-Roussy during a 1-year period. Margins were considered positive if extensive pathological examination revealed either carcinoma within 5 mm or dysplasia. We tested five tetranucleotide microsatellite markers (UT5085, L17686, D9S753, ACTBP2, and CSF1R) in the tumor specimens and paired surgical margins of the patients whose margins were negative on pathological examination.

RESULTS

Pathological examination revealed that among the 76 patients, 22 had positive margins; therefore, these patients were excluded. Of the 54 remaining patients, 26 (48%) had tumors informative for markers UT5085, L17686, or both; the other 3 markers were not informative. Seven (27%) of the 26 informative tumors had the same instability pattern in the surgical margins. At a median follow-up of 26 months, 5 of the 7 local recurrences occurred in patients with molecularly positive surgical margins. A strong, independent association was found between positive surgical margins and local recurrence (P = 0.01; hazard ratio, 6.49).

CONCLUSIONS

Tetranucleotide microsatellite instability in surgical margins may be a useful biomarker to predict local recurrence of head and neck squamous cell carcinoma in patients with apparently disease-free margins.

Molecular markers for diagnosis and prognosis

A plethora of aberrations are associated with progress and outcome for head and neck cancer patients and some have been shown to provide prognostic information independent of the TNM staging system. These findings justify future studies that will harness recent advances in technologies to refine the range of molecular markers available. Important lessons have been learnt during the last two decades, particularly the need to perform multivariate analysis and to combine information derived from several molecular markers. At present the overall evidence is insufficient to alter clinical practice or to consider restricting clinical trials of new adjuvant to subsets of patients, identified on the basis of the use of molecular markers. However, a number of key prospective clinical studies are in progress and we can be optimistic that in the near future clinical research incorporating specific markers may provide new criteria for defining risk of relapse or of developing a new primary tumour, and guide the choice of optimal adjuvant treatment after surgery. The only way to truly validate a marker is to incorporate it into large clinical trials, and it is anticipated that the new treatment options that are on the horizon, that are likely to be an improvement on radiotherapy alone, will provide opportunities to help translate this laboratory research into clinical practice.