Importance of DICKKOPF-1 (DKK-1) on mesenchymal stem cell expansion from bone marrow of patients with lung and breast cancer.

HOFER EL.; LABOVSKY V.; ROMANIUK A.; FELDMAN L,; BORDENAVE RH,; LEVIN MJ.; CHASSEING NA.

Buenos Aires, Argentina.

Jornada; VIII Jornadas Multidisciplinarias de la Sociedad Argentina de Biología.; 2006

Sociedad Argentina de Biología.

IMPORTANCE OF DICKKOPF-1 (DKK-1) ON MESENCHYMAL STEM CELL (MSC) EXPANSION FROM BONE MARROW (BM) OF PATIENTS WITH LUNG (LCP) AND BREAST CANCER (BCP). Although some of the in-vitro growth characteristics of human BM-MSC have been documented, the molecular mechanisms by which MSC regulate their own growth in culture are poorly understood.  There is no explanation for the observation that when early passage MSC are replated at low density, they display a lag period of 3 days, followed by a phase of rapid exponential growth, and then enter a stationary phase. When BM mononuclear cells are cultured in a medium with 20% FBS, MSC and stromal progenitors give fibroblast colonies (CFU-F) after 14 days. MSC-self renewal and the induction of CFU-F occurred between days 3-7 while the increase in colony size occurred between days 7-14. Works suggest that Dkk-1 allow the MSC and the stromal progenitors from CFU-F reenter the cell cycle. At the end of lag phase and in the early log phase, MSC or CFU-F secretes Dkk-1. We have previously described that BM from untreated advanced LCP and BCP have significantly lower # of CFU-F and a significantly decreased of CFU-F size vs. the values normal volunteers (NV). We also found that these patients have no difference in the levels of most growth and inhibitor factors of CFU-F formation in conditioned mediums (CoM, 7 and 14 days) of CFU-F cultures vs. NV.  Thus, we have now further evaluated the levels of Dkk-1 in CoM (7 and 14 days) of CFU-F cultures and of confluence primary cultures (CoM from the last 7 days) from BM of 12 NV, 13 LCP and 15 BCP by ELISA development kit. Dkk-1 levels were expressed as X±SE (pg/ml): CoM of CFU-F (day7): LCP=2,015±429a, BCP=1,798±469 and NV=1,602±399b and 14day: LCP=4,276±691a,c, BCP=2,665±611d and NV=14,484±4,034b,c,d (a=p<0.01; b=p<0.0001; c=p<0.0008; d=p<0.0002; Mann Whitney). These patients also had a deficient cloning capacity of BM-MSC vs. NV as we previously published (#CFU-F from LCP and BCP vs. NV=p<0.001, Kruskal Wallis) and a significant decrease of the # of stromal cells/ field of CFU-F (LCP and BCP vs. NV= p<0.01 and 0.05, respectively, Dunn Multiple Comparison). No difference was found in Dkk-1 levels in CoM of confluence primary cultures from patients and NV.  In conclusion, the low #of CFU-F and the decrease of CFU-F size in patient cultures could be consequence of a decreased secretion of Dkk-1 in 14 days CoM of CFU-F.