Temporal trends and clinical correlates for the ret/PTC1 mutation in papillary thyroid carcinoma

Mutation profile of differentiated thyroid tumours in an Australian urban population

BACKGROUND

The majority of differentiated thyroid cancers are characterised by one of several point mutations or gene rearrangements. Limited data are available on the prevalence and clinical correlations of these mutations in the Australian population.

AIMS

The aim of the present study was to characterise the mutation profile of differentiated thyroid tumours in the local population.

METHODS

The study involved 148 patients with differentiated thyroid cancer. The following tumours were examined: 109 papillary carcinomas (PTC), 27 follicular carcinomas (FC) and 12 Hurthle cell carcinomas (HCC). Polymerase chain reaction (PCR) was performed for BRAF and RAS mutations (RNA and DNA) as well as for RET/PTC rearrangements and PAX8-PPARγ translocations (RNA). Clinicopathological parameters and outcome data were analysed according to BRAFV600E status in PTC and RAS mutation status in FC.

RESULTS

BRAFV600E was identified in 74/109 (68%) PTC. BRAFV600E was not significantly correlated with clinicopathological features of aggressive disease. At a median follow up of 48 months, there was no significant difference between BRAFV600E and wild-type BRAF PTC with respect to the rates of nodal recurrence, distant metastases or disease-specific death. In FC, RAS mutations (five NRAS and three HRAS) were present in 8/27 (30%) tumours. RAS mutation was significantly associated with widely invasive histology (P = 0.01) and distant metastases (P = 0.01) on follow up.

CONCLUSION

In the present study, BRAF mutation was not associated with negative prognostic indicators or adverse outcomes in PTC. RAS mutation was positively correlated with aggressive features in FC suggesting potential prognostic utility, although confirmation is required from larger studies.

Contribution of immunocytochemical stainings for galectin-3, CD44, and HBME1 to fine-needle aspiration cytology diagnosis of papillary thyroid carcinoma

In cytology practice some papillary thyroid carcinoma (PTC) cases have indeterminate diagnoses and overlapping cytological features with benign lesions. This study was undertaken to find out if immunocytochemistry using Galectin-3, CD-44 and HBME-1 could be of help in such situations. Forty-six cases consisting of 22 malignancy (PTC) cases, 7 suspicious of (S/O) PTC, 1 follicular neoplasm, 5 follicular lesion of undetermined significance (FLUS), and 11 benign (colloid goiter) cases diagnosed by FNA were included in this study. Staining reactions were graded in a sliding scale of -, 1+, 2+, 3+, and 4+. In an assessment of 100 cells, each cell with weak, and moderate to strong positive reaction were assigned a score of 1 and 4, respectively. Staining reaction of ≥+2 and scores >100 were considered positive. Frequency of cases with ≥+2 reaction, and scores >100 for each of Galectin-3, CD-44, and HBME-1 were significantly higher in PTC or combined PTC and S/O PTC cases as compared with FLUS and benign cases taken together (P = 0.01744 to 0.00000). When the cases were compared according to histological malignant and benign diagnoses, the difference was also significant in respect of ≥+2 reaction, and scores >100 for Galectin-3 and CD44 (P = 0.04923 to 0.00947); however, there was no significant difference, when these parameters for HBME1 were compared. Galectin 3, CD 44, and to some extent HBME 1 are useful immunocytochemical parameters with potential to support FNAC diagnosis of PTC, especially in situations with difficult differential diagnoses.

Ultra-sensitive detection of mutated papillary thyroid carcinoma DNA using square wave stripping voltammetry method and amplified gold nanoparticle biomarkers

This study presents an ultra-sensitive technique for the electrochemical detection of the mutated BRAF gene associated with papillary thyroid carcinomas (PTC). In the proposed approach, a biotinylated 30-nucleotides probe DNA was immobilized in a streptavidin-modified 96-well microtiter plate and the free active sites of the streptavidin were blocked using biotinylated bovine serum albumin (BSA). The biotinylated target DNA was then added and allowed to hybridize with the immobilized probe DNA for 30min. Subsequently, streptavidin-labeled gold nanoparticles were added, and a nanoparticle enlargement process was performed using gold ion solution and formaldehyde reductant. The gold particles were then dissolved in bromide and DNA hybridization detection process was performed using a square wave stripping voltammetry (SWSV) technique. The results indicated a stable SWSV response in differential detection between blank solution and target DNA solution with a concentration of 130aM. Moreover, the coefficient of determination (R(2)) of the semi-log plot of the SWSV response current against the target DNA concentration (0.52-1300aM) was found to be 0.9982. The detection limit was estimated to be 0.35aM (based on a signal-to-noise ratio of 3:1). This value was approximately three orders of magnitude lower than that obtained using the same method but without gold amplification process. Finally, the proposed approach is successful in differentiating between the mutant and wildtype BRAF sequences that are present in genuine 224-nucleotides DNA.

The thyroid dose burden in medical imaging A re-examination

Radiation is the best defined causative factor in thyroid cancer. The thyroid is especially susceptible to injury from radiation to which it may be exposed in a variety of circumstances in addition to natural background: radiotherapy, including, historically, therapy of such benign conditions as ring worm and haemangiomata, radiation exposure in nuclear accidents and fallout from nuclear bomb tests, and diagnostic exposures, particularly in the relatively high dose CT examination of head and neck. Both use of CT and the incidence of thyroid cancer appear to be increasing worldwide and it has been suggested that there may be a causative relationship between the two. It has been further posited that the iodine content of the thyroid might play a role in increasing the radiation dose absorption. Indeed, on the same basis, iodine administered in the form of an X-ray contrast-enhancing agent might also be expected to play some role in increasing thyroid radiation absorption resulting in a yet higher dose burden in any give circumstances than is generally assumed. In view of the importance of these ideas we have performed some calculations to estimate the magnitude of the iodine effects. We conclude that they are not great enough to cause concern.

Rearrangement Analysis in Archival Thyroid Tissues: Punching Microdissection and Artificial RET/PTC 1–12 Transcripts

BACKGROUND

In few papillary thyroid carcinomas (PTC) and oxyphilic thyroid carcinoma, the clinical impact of the 15 known RET hybrid oncogene variants (RET/PTC 1 to 12, 1L, 3r2, 3r3) is subject to controversial discussions. Large patient cohorts and exploitation of pathological thyroid tissue archives are essential to study the prognostic significance of RET/PTC chimeras.

MATERIALS AND METHODS

Formalin-fixed and paraffin-embedded thyroid neoplasms were subjected to manual punching macrodissection and subsequent extraction of total RNA. Following reverse transcriptase polymerase chain reaction (RT-PCR)-based screening for RET rearrangements, hybrid-specific expression analyses were carried out for samples indicative of chimeric transcripts. Due to lack of tissue specimen harboring the rare RET chimeras, artificially constructed hybrid sequences of all known RET/PTC variants served as PCR controls.

RESULTS

Manual punching dissection successfully diminished RET wild-type contamination originating from C-cells dispersed throughout normal thyroid tissues. The average amount of 27.4 mug RNA extracted allowed for repeated molecular analyses (>60 PCRs). Hybrid-specific expression analysis identified 10 of 15 RET rearrangements (8x RET/PTC 1, 2x RET/PTC 3, 5x RET/PTC x) to be found in 54 oxyphilic thyroid tumors examined. Successful amplification of each artificial hybrid sequence ensured the absence of rare chimeric transcripts. Therefore, RET/PTC x represent either common chimeras not amplifiable due to archival RNA degradation or truly novel hybrid oncoproducts.

CONCLUSIONS

The fast and simple techniques described here were used to examine oxyphilic carcinomas and adenomas. These microdissection and RT-PCR procedures can easily be put into practice in any molecular biology research laboratory to enable screening of large numbers of archival thyroid tumors for known as well as yet unknown RET rearrangements.

ret/PTC and BRAF act as distinct molecular, time-dependant triggers in a sporadic Irish cohort of papillary thyroid carcinoma

The purpose of this study was to assess BRAF mutation rates in various thyroid tissues and to investigate if concomitant mutations with ret/PTC activation occurred in inflammatory and neoplastic lesions. To this end, we developed a novel Taqman based screening assay for the common T1799A BRAF mutation. Heterozygous T1799A mutations were detected in 13 of 34 (44%) papillary thyroid carcinomas (PTCs) tested. No such mutations were detected in the other tissue types tested. Concomitant presence of both oncogenes was reported in 5 of the 34 PTCs. A significant temporal trend was observed, with ret/PTC chimera detected for the most part before 1997 and BRAF mutations being more prevalent after 1997. The results suggest that some environmental/etiological agent(s) may have influenced the pathobiology of thyroid tumor development, among the population examined, over time.