PLAGL1 gene function during hepatoma cell proliferation

VEGA BENEDETTI A.F.; VANNI R.; SAUCEDO C.N.; PARADA L.A.; ZAVATTARI P.

Salta

Jornada; XV Jornadas Académicas de la Facultad de Ciencias de la Salud, UNSa; 2016

Facultad de Ciencias de la Salud, UNSa

PLAGL1 gene encodes a homonymous Zinc-finger protein thatregulates cell cycle arrest and apoptosis. Such regulation occurs through pathwaysthat include p53 and PPARγ, which induce p21Cip1, a cell cycle regulator. To elucidateits role in tumor growth, we studied the transcript and protein levels ofPLAGL1, p53, PPARγ and p21 in hepatoma proliferating cells.Hepatoma celllines HepG2, Huh7, PLC and SkHep1, andnormal fibroblasts (control) were cultured according to standard protocols forproliferation studies. Then,cell count, flow cytometry, Western blot and RT-qPCR analyses were performed at48, 72 and 96hs. The transcript level was quantified by the 2-ΔΔCtmethod, using PPIA as a reference gene. Protein level was quantified by the ImageJ program, using Actinas a loading control. Statistic analyses wereperformed by ANOVA.We determined that fibroblasts have lower proliferation rates than cancercell lines. In general, the PLAGL1 mRNAlevel was significantly higher  in fibroblasts than in tumor cell lines, whichexhibited distinct patterns of transcription and expression. In fibroblasts,the PLAGL1 transcript and expression levels decreased significantly after 48hspost release from serum starvation, and then gradually increased until 96hs, while p53 and p21 followed this PLAGL1pattern. In contrast, the tumor cell lines showed uniform low transcription and expression levels of PLAGL1 during theexperimental period, except for SkHep1 cells. Despite of this, the transcript and expressionlevels of p53 and p21 presented different dynamics among tumor cell lines. RegardingPPARγ, our experimentsdemonstrated that its transcriptional level was significantly low during proliferationin normal and  and tumor cell lines, exceptonly for Huh7.Our results show that there is not a straightforward functional relationship between PLAGL1 and p53, PPARγ and p21 in the cell-cycle control of hepatoma cells.