Potential utility of telomere length assessment in breast cancer in a diagnostic histopathology setting.

INTRODUCTION: Telomeres shorten with cell cycling but are restored above mortality threshold in many cancers making them potentially exploitable for differentiating malignant from benign tissues, and for cancer evaluation. MATERIALS AND METHODS: We assessed telomeres in a diagnostic histopathology setting using quantitative fluorescence in situ hybridisation on 33 fibroadenoma (FA) and 73 invasive breast carcinoma of no special type (IBC-NST) (prototypes of benign and malignant breast tumours, respectively) with paired benign, non-lesional breast tissues (BNL). Telomere lengths were expressed as telomere/chromosome-2-centromere ratio (TCR). The telomere length cut-off for malignancy was also determined. RESULTS: Mean TCR of IBC-NST was significantly shorter than FA and BNL (p<0.001). Mean TCR of FA was shorter than BNL but not significantly (p>0.05). TCR cut-off for IBC-NST based on FA was ≤0.29 (sensitivity=75.3%; specificity=78.8%), and ≤0.30 based on BNL (sensitivity=76.7%; specificity=89.0%). TCR of IBC-NST did not differ in relation to histological grade, nodal and hormonal status (p>0.05) but was significantly shorter in HER2-overexpressing cancers (p<0.05). CONCLUSION: We have demonstrated a first-step to the development of methodologybased cut-off values of mean telomere length for distinguishing benign from malignant breast tissues. Telomere length may not value-add to the standard prognostic and predictive parameters, but has potential in relation to HER2.

FISHing for 1p19q codel in oligodendroglioma.

Together with isocitrate dehydrogenase (IDH) mutation, co-deletion of 1p19q (1p19q codel) is a prerequisite for diagnosis of oligodendroglioma, making it imperative that histopathology laboratories introduce testing for 1p19q codel. To date there is still no consensus reference range and cut-offs that confirm deletion of 1p or 19q. We embarked on determining our reference range in 11 formalinfixed, paraffin-embedded non-neoplastic brain tissue using fluorescence in situ hybridisation (FISH) with the Vysis 1p36/1q25 and 19q13/19p13 FISH Probe Kit (Abbott Molecular Inc., USA). At same time we attempted to validate our methodology in 13 histologically-confirmed IDH-mutant oligodendrogliomas. For 1p, percentage cells with deletion (range=8-23%; mean±SD = 15.73±5.50%) and target: control (1p36:1q25) ratio (range = 0.89-0.96; mean±SD = 0.92±0.03) in non-neoplastic brain, differed significantly (p<0.000) from oligodendroglioma (percentage cells with deletion: range = 49-100%; mean±SD = 82.46±15.21%; target:control ratio range:0.50-0.76; mean±SD = 0.59±0.08). For 19q, percentage cells with deletion (range = 7-20%; mean±SD = 12.00±3.49%) and target:control (19q13/19p13) ratio (range:0.90-0.97; mean±SD = 0.94±0.02) in non-neoplastic brain also differed significantly from oligodendroglioma (percentage cells with deletion: range = 45-100%; mean±SD = 82.62±18.13%; target:control ratio range:0.50-0.78; mean±SD = 0.59±0.09). Using recommended calculation method, for diagnosis of 1p deletion, percentage of cells showing deletion should be >32-33% and/or target:control ratio <0.83. For 19q, percentage of cells showing deletion should be >22% and target:control ratio <0.88. Using these cut-offs all 13 oligodendroglioma demonstrated 1p19q codel.

Melanocortin receptor-mediated mobilization of intracellular free calcium in HEK293 cells.

Mouse melanocortin receptors, MC1-R, MC3-R, MC4-R, and MC5-R, when expressed in HEK293 cells and stimulated with either alpha-melanocyte-stimulating hormone (alpha-MSH) or desacetyl-alpha-MSH, mediate increases in intracellular free calcium concentration ([Ca(2+)](i)) with EC(50) values between 0.3 and 4.3 nM. The increase in [Ca(2+)](i) is cholera toxin sensitive and pertussis toxin insensitive. The mechanism involves calcium mobilization from intracellular stores without a transient rise in inositol trisphosphate. Mouse agouti protein (55 nM) is a competitive antagonist of alpha-MSH (6-fold) and desacetyl-alpha-MSH (8-fold), coupling the mMC1-R to increased [Ca(2+)](i). Agouti protein (55 nM) significantly increased the EC(50) for alpha-MSH (3-fold), and 550 nM agouti protein significantly increased the EC(50) for desacetyl-alpha-MSH (4-fold), coupling the mMC4-R to a rise in [Ca(2+)](i). However, agouti protein antagonism of the MC4-R may not be competitive since there was a trend for the maximum response to also increase. There was no significant antagonism of the MC3-R and MC5-R by agouti protein (55 nM). Understanding the physiological relevance of the transduction of a calcium signal by melanocortin peptides may be important for future development of therapeutic targeting of the melanocortin receptors.