Simple method for pretreatment of tissue sections for the detection of apoptosis by in situ end-labelling and in situ nick translation

Extensive DNA fragmentation in oxyphilic cell lesions of the thyroid

The in situ end-labeling (ISEL) method demonstrates DNA fragmentation, commonly regarded as a marker of apoptosis. We investigated by the ISEL procedure a series of 52 thyroid lesions, including 24 lesions of mitochondrion-rich oxyphilic cells, both benign and malignant, and 28 non-oxyphilic control tumors. A high percentage of nuclear ISEL staining (approximating to 100% in most cases) was observed in the vast majority of oxyphilic cells from both adenomas and carcinomas, in the absence of morphological apoptotic changes and with no immunocytochemical evidence of caspase activation. This pattern of DNA fragmentation was not observed in non-oxyphilic lesions and was confirmed in total extracted DNA. Moreover, a peculiar cytoplasmic staining was also observed in oxyphilic cells from both benign and malignant lesions, probably related to abnormal fragmentation of mitochondrial DNA. Similar staining patterns were detected in oxyphilic cell tumors of other organs (parathyroids, salivary glands, and kidneys). These findings are consistent with an extensive DNA fragmentation peculiar to oxyphilic cells, which is not directly related to apoptosis and whose origin and biological significance are presently unknown.

Apoptosis in squamous cell carcinoma of the lung: correlation with survival and clinicopathological features

AIMS

Apoptosis is recognised as a physiological mechanism for controlling cell numbers and its subversion is thought to contribute to carcinogenesis. The aims of this study were to measure the apoptotic index (AI) in a series of squamous cell carcinomas (SCCs) of the lung using standard histological staining and confirm this by immunohistology using an antibody to an apoptosis specific protein (ASP), and to seek to correlate the AI with clinicopathological parameters.

METHODS

Sections of 134 SCCs were stained by haematoxylin and eosin (H&E) for counting apoptotic bodies of determine the AI (number of apoptotic bodies/10,000 tumour cells); 26 of these were also stained with anti-ASP antibody and the proportion of ASP positive cells counted. Clinical data were obtained from hospital notes.

RESULTS

The mean AI obtained by H&E staining of all 134 SCCs was 30.3 (SD, 24.75). Anti-ASP staining allowed easy identification of apoptotic bodies, and generated a somewhat higher index (mean, 51.4; SD 39); this was not a result of the selection of tumours because the AI by H&E in the subset stained with anti-ASP was 31.1. Regression analysis showed that the correlation between the two values of AI was highly significant (Rs = 0.9760; p < 0.001), indicating that the two methods were both reliable measures of apoptosis but that the anti-ASP staining is the more sensitive method. The tumours were grouped into high AI (> 50) and low AI (< 50) and survival analysis was carried out. The mean survival of the high AI group was 109 weeks and of the low AI group 72 weeks (p = 0.036).

CONCLUSIONS

Anti-ASP staining is a reliable, easy, and sensitive method for assessing apoptosis in tumour sections and confirms the validity of the AI obtained by H&E staining. AI is a guide to the behaviour of SCCs of the lung.

Comparison of in situ methods to assess DNA cleavage in apoptotic cells in patients with breast cancer

BACKGROUND

Apoptosis has a role in many cellular processes including development, normal tissue homeostasis, and malignancy. This aspect of research is relatively new with distinct methods of analysing disparate biochemical and genetic events to measure apoptotic cells. The use of biotinylated nucleotides to identify DNA strand breaks is a commonly reported method of estimating cells numbers undergoing apoptosis; however, investigators report inconsistent results for a variety of reasons.

AIMS AND METHOD

To compare two in situ techniques of measuring apoptosis: in situ nick translation (ISNT) and TdT mediated dUTP-biotin nick end labelling (TUNEL); and to assess DNA cleavage in 20 paired paraffin wax embedded breast cancer tissues from patients; one group who had received no prior treatment and one group who had received chemohormonal treatment.

RESULTS AND CONCLUSIONS

Apoptotic scores obtained from paraffin wax embedded human breast cancer after using ISNT and TUNEL methods were not significantly different (p = 0.11). A strong correlation between scores obtained from the two techniques was found (r = 0.758, p < 0.0001). Optimisation of both techniques is crucial to ensure maximal assay performance in breast cancer tissue.