A novel immunohistochemical method to estimate cell-cycle phase distribution in archival tissue: implications for the prediction of outcome in XXXX .

@entity5 @entity9965 @entity12840 @entity8189 @entity14 @entity7596 @entity694 @entity420 @entity1586
An immunohistochemical method for assessing cell-cycle phase distribution in colorectal resection specimens would enable phase data to be incorporated into diagnostic algorithms for the estimation of prognosis and response to adjuvant chemotherapy in @entity14 . In contrast to flow cytometry, an immunohistochemical method would also allow the phase distribution to be examined within morphologically heterogeneous regions of @entity5 . Paraffin sections of normal colon (n = 25), @entity1586 (n = 15), and @entity694 (n = 30) were analysed by immunohistochemistry using antibodies against markers of cell-cycle entry, @entity9965 and Ki67, and putative markers of the cell-cycle phase, cyclins @entity12840 (putative markers of G1 phase), @entity7596 (S phase), cytoplasmic @entity8189 (G2 phase), and phosphohistone H3 (M phase). The phase specificity of each marker was assessed by examining the degree of co-expression of adjacent phase markers using double-antibody fluorescence confocal microscopy and by comparison with flow cytometric analysis performed on adjacent tissue sections. The S-phase specificity of detectable @entity7596 was also assessed in combination with in situ DNA replication using fluorescence confocal microscopy. All cells expressing phase markers co-expressed @entity9965 . Adjacent phase markers were not significantly co-expressed, confirming the relative specificity of these markers in tissue sections of colon. Cell-cycle phase distribution, calculated by immunohistochemistry, compared well with phase analyses obtained by flow cytometry. No cells expressed @entity7596 in the absence of active DNA replication. The S-phase labelling index, as defined by detectable @entity7596 expression, showed a positive correlation with the @entity9965 labelling index and increased in the progression from normal colon to @entity420 . In conclusion, a combination of these cell-cycle phase markers can be used to calculate the distribution of cells throughout each phase of the cell cycle in colorectal tissue sections. Detectable @entity7596 can be used as a surrogate marker of S phase and may be of value in predicting prognosis and response to adjuvant therapy.
