Figure 3
Illustration of the gold standard method of Ki-67 nuclear gradient (NG) determination during the cell cycle obtained from published articles. During the G0 phase, the Ki-67 NG is weakly detectable. In early G1 phase, an inconspicuous nucleolus appears, and Ki-67 proteins can be visualized initiating a new cycle (
1616. van Dierendonck JH, Keijzer R, van de Velde CJ, Cornelisse CJ. Nuclear distribution of the Ki-67 antigen during the cell cycle: comparison with growth fraction in human breast cancer cells. Cancer Res 1989; 49: 2999-3006.,
1717. Matheson TD, Kaufman PD. The p150N domain of chromatin assembly factor-1 regulates Ki-67 accumulation on the mitotic perichromosomal layer. Mol Biol Cell 2017; 28: 21-29, doi: 10.1091/mbc.e16-09-0659.
https://doi.org/10.1091/mbc.e16-09-0659...
,
2525. Norton JT, Wang C, Gjidoda A, Henry RW, Huang S. The perinucleolar compartment is directly associated with DNA. J Biol Chem 2009; 284: 4090-4101, doi: 10.1074/jbc.M807255200.
https://doi.org/10.1074/jbc.M807255200...
,
2626. Bridger JM, Kill IR, Lichter P. Association of pKi-67 with satellite DNA of the human genome in early G1 cells. Chromosome Res 1998; 6: 13-24, doi: 10.1023/A:1009210206855.
https://doi.org/10.1023/A:1009210206855...
). The Ki-67 gradient is detected as multiple spots regularly dispersed in the initial G1 phase (
1818. Balancin ML, Baldavira CM, Prieto TG, Machado-Rugolo J, Farhat C, Assato AK, et al. Dissecting and reconstructing matrix in malignant mesothelioma through histocell-histochemistry gradients for clinical applications. Front Med (Lausanne) 2022; 9: 871202, doi: 10.3389/fmed.2022.871202.
https://doi.org/10.3389/fmed.2022.871202...
,
1919. Goldstraw P, Chansky K, Crowley J, Rami-Porta R, Asamura H, Eberhardt WEE, et al. The IASLC lung cancer staging project: proposals for revision of the TNM stage groupings in the forthcoming (Eighth) edition of the TNM classification for lung cancer. J Thorac Oncol 2016; 11: 39-51, doi: 10.1016/j.jtho.2015.09.009.
https://doi.org/10.1016/j.jtho.2015.09.0...
,
2121. Kill IR. Localisation of the Ki-67 antigen within the nucleolus. Evidence for a fibrillarin-deficient region of the dense fibrillar component. J Cell Sci 1996; 109: 1253-1263, doi: 10.1242/jcs.109.6.1253.
https://doi.org/10.1242/jcs.109.6.1253...
). During the progression of the G1 phase, these spots merge with each other, forming irregular clones bordering one or two nucleoli as observed in the late G1 phase (
1919. Goldstraw P, Chansky K, Crowley J, Rami-Porta R, Asamura H, Eberhardt WEE, et al. The IASLC lung cancer staging project: proposals for revision of the TNM stage groupings in the forthcoming (Eighth) edition of the TNM classification for lung cancer. J Thorac Oncol 2016; 11: 39-51, doi: 10.1016/j.jtho.2015.09.009.
https://doi.org/10.1016/j.jtho.2015.09.0...
,
2121. Kill IR. Localisation of the Ki-67 antigen within the nucleolus. Evidence for a fibrillarin-deficient region of the dense fibrillar component. J Cell Sci 1996; 109: 1253-1263, doi: 10.1242/jcs.109.6.1253.
https://doi.org/10.1242/jcs.109.6.1253...
,
2525. Norton JT, Wang C, Gjidoda A, Henry RW, Huang S. The perinucleolar compartment is directly associated with DNA. J Biol Chem 2009; 284: 4090-4101, doi: 10.1074/jbc.M807255200.
https://doi.org/10.1074/jbc.M807255200...
). In late G1, S, and G2 phases (interphase), the Ki-67 gradient represents the heterochromatin, perinucleolar heterochromatin, and nucleolus (
1515. Cajal SRY, Sesé M, Capdevila C, Aasen T, De Mattos-Arruda, Diaz-Cano SJ, et al. Clinical implications of intratumor heterogeneity: challenges and opportunities. J Mol Med (Berl) 2020; 98: 161-177, doi: 10.1007/s00109-020-01874-2.
https://doi.org/10.1007/s00109-020-01874...
,
1616. van Dierendonck JH, Keijzer R, van de Velde CJ, Cornelisse CJ. Nuclear distribution of the Ki-67 antigen during the cell cycle: comparison with growth fraction in human breast cancer cells. Cancer Res 1989; 49: 2999-3006.,
1919. Goldstraw P, Chansky K, Crowley J, Rami-Porta R, Asamura H, Eberhardt WEE, et al. The IASLC lung cancer staging project: proposals for revision of the TNM stage groupings in the forthcoming (Eighth) edition of the TNM classification for lung cancer. J Thorac Oncol 2016; 11: 39-51, doi: 10.1016/j.jtho.2015.09.009.
https://doi.org/10.1016/j.jtho.2015.09.0...
). In S and G2 phases, the Ki-67 gradient intensifies, forming asymmetrical dense granules dispersed throughout the nucleoplasm (
1313. Yano S, Tazawa H, Kagawa S, Fujiwara T, Hoffman RM. FUCCI real-time cell-cycle imaging as a guide for designing improved cancer therapy: a review of innovative strategies to target quiescent chemo-resistant cancer cells. Cancers (Basel) 2020; 12: 2655, doi: 10.3390/cancers12092655.
https://doi.org/10.3390/cancers12092655...
,
1515. Cajal SRY, Sesé M, Capdevila C, Aasen T, De Mattos-Arruda, Diaz-Cano SJ, et al. Clinical implications of intratumor heterogeneity: challenges and opportunities. J Mol Med (Berl) 2020; 98: 161-177, doi: 10.1007/s00109-020-01874-2.
https://doi.org/10.1007/s00109-020-01874...
). In prophase, the location of Ki-67 staining intensity shifts from the perinucleolar regions, nucleolus, and heterochromatin to the perichromosomal layer and fills the entire nucleus (
1313. Yano S, Tazawa H, Kagawa S, Fujiwara T, Hoffman RM. FUCCI real-time cell-cycle imaging as a guide for designing improved cancer therapy: a review of innovative strategies to target quiescent chemo-resistant cancer cells. Cancers (Basel) 2020; 12: 2655, doi: 10.3390/cancers12092655.
https://doi.org/10.3390/cancers12092655...
,
1616. van Dierendonck JH, Keijzer R, van de Velde CJ, Cornelisse CJ. Nuclear distribution of the Ki-67 antigen during the cell cycle: comparison with growth fraction in human breast cancer cells. Cancer Res 1989; 49: 2999-3006.,
3333. Sasaki K, Murakami T, Kawasaki M, Takahashi M. The cell cycle associated change of the Ki-67 reactive nuclear antigen expression. J Cell Physiol 1987; 133: 579-584, doi: 10.1002/jcp.1041330321.
https://doi.org/10.1002/jcp.1041330321...
). In prometaphase, the nucleoli cannot be identified, and Ki-67 is densely condensed with peripheral chromosomes, which move to the center, characterizing the metaphasic stage (
1313. Yano S, Tazawa H, Kagawa S, Fujiwara T, Hoffman RM. FUCCI real-time cell-cycle imaging as a guide for designing improved cancer therapy: a review of innovative strategies to target quiescent chemo-resistant cancer cells. Cancers (Basel) 2020; 12: 2655, doi: 10.3390/cancers12092655.
https://doi.org/10.3390/cancers12092655...
,
1616. van Dierendonck JH, Keijzer R, van de Velde CJ, Cornelisse CJ. Nuclear distribution of the Ki-67 antigen during the cell cycle: comparison with growth fraction in human breast cancer cells. Cancer Res 1989; 49: 2999-3006.,
3333. Sasaki K, Murakami T, Kawasaki M, Takahashi M. The cell cycle associated change of the Ki-67 reactive nuclear antigen expression. J Cell Physiol 1987; 133: 579-584, doi: 10.1002/jcp.1041330321.
https://doi.org/10.1002/jcp.1041330321...
). During telophase, the Ki-67 gradient remains elevated to maintain chromosome separation. When the separation of the daughter cells begins in anaphase, the cell cycle is completed (
1313. Yano S, Tazawa H, Kagawa S, Fujiwara T, Hoffman RM. FUCCI real-time cell-cycle imaging as a guide for designing improved cancer therapy: a review of innovative strategies to target quiescent chemo-resistant cancer cells. Cancers (Basel) 2020; 12: 2655, doi: 10.3390/cancers12092655.
https://doi.org/10.3390/cancers12092655...
,
1616. van Dierendonck JH, Keijzer R, van de Velde CJ, Cornelisse CJ. Nuclear distribution of the Ki-67 antigen during the cell cycle: comparison with growth fraction in human breast cancer cells. Cancer Res 1989; 49: 2999-3006.,
3333. Sasaki K, Murakami T, Kawasaki M, Takahashi M. The cell cycle associated change of the Ki-67 reactive nuclear antigen expression. J Cell Physiol 1987; 133: 579-584, doi: 10.1002/jcp.1041330321.
https://doi.org/10.1002/jcp.1041330321...
).