Characterization of proliferating cell nuclear antigen (PCNA) isoforms in normal and cancer cells: There is no cancer‐associated form of PCNA

Abstract

In order to clarify the status of PCNA in normal and transformed cells, we performed analysis of this protein by 2D-PAGE, Western blot and mass spectrometry. All the cell lines examined contained the major PCNA form (pI 4.57/30 kDa), that is not post-translationally modified. In addition to the major form, two minor isoforms (pI 4.52/30 kDa and pI 4.62/30 kDa) were also detected in all the cell lines examined. However, the level of PCNA in cancer cells is 5-6 folds higher than those in primary and most of the immortalized cells. Taken together, the significant difference in PCNA status between cancer and normal cells is not at the post-translational modifications but in the overall levels of PCNA. Crown

Proliferating cell nuclear antigen in the cytoplasm interacts with components of glycolysis and cancer

“…As expected from our previous work [18], the level of PCNA protein was much higher in MDA-MB468 than HMEC (compared Fig. 1A vs C).…”

“…A PCNA ring may bind to different protein partners at different time and space to carry out specific tasks [3,5,16,17]. We previously found that the level of PCNA is substantially elevated in cancer cells, which is only notable difference between cancer and normal cells with respect to PCNA protein [18]. Since PCNA-protein interactions may be affected by elevated protein concentration at a given time and space, our finding raises the possibility that PCNA in cancer cells may interact with certain proteins that do not normally interact with PCNA in normal cells.…”

The immortalizing and transforming ability of two common human papillomavirus 16 E6 variants with different prevalences in cervical cancer

“…In-gel trypsin digestion and generation of peptide spectra by matrix-assisted laser desorption/ionization were performed as described previously, with some modifications (Naryzhny and Lee, 2007). The produced peptides were collected directly from the gel plug digest, mixed (1:1) with a-cyano-4-hydroxycinnamic acid matrix solution (Fluka, Buchs, Switzerland), 10 mg/ml, in 50% acetonitrile, 20% ethanol, 0.01% trifluoroacetic acid, applied to the target plate, crystallized and analyzed by matrix-assisted laser desorption/ionization on a Micro MX instrument (Waters Inc., Milford, MA, USA).…”

Development of barcode and proteome profiling of glioblastoma

“…Все процедуры проводили, следуя протоколу, описанному ранее [15]. После разделения с помощью 2DE и окрашивания с использованием Кумасси R350 кусочки геля диаметром 1,5 мм, соответствующие белковым пятнам, вырезали, используя наконечники для микропипеток, и частично обесцвечивали 15-минутной инкубацией в 500 мкл 50%-ного ацетонитрила (ACN), содержащего 25 мМ бикарбонат аммония.…”

“…Образцы готовили, по описанной ранее методике [15,16]. Клетки (~10 7 ), содержащие до 2 мг белка, лизировали в 100 мкл буфера (7 М мочевина, 2 М тиомочевина, 4% CHAPS, 1% дитиотреитол (ДTT), 2% амфолиты, pH 3-10, смесь протеазных ингибиторов).…”