SummaryMammalian aging of many tissues is associated with a decline in the replicative and functional capacity of somatic stem cells. Understanding the basis of this decline is a major goal of aging research. Human bone marrow-derived multipotent stromal cells (MSCs) have been applied in the treatment of fracture nonunion. Clinical application of MSCs requires abundant cells that can be overcome by ex vivo expansion of cells, but often at the expense of stemness and differentiation potentiality. We first demonstrated that late-passage MSCs exhibited decreased proliferation capacity, reduced expression of stemness markers such as Oct-4 and Nanog, and deterioration of osteogenic potential. Further, late-passage MSCs showed increased expression of p21 Cip1 ⁄ Waf1 (p21), an inhibitor of the cyclin-dependent kinase. Knockdown of p21 by lentivirus-mediated shRNAs against p21 in late-passage MSCs increased the proliferation capacity, the expression of Oct-4 and Nanog, and osteogenic potential compared with cells transduced with control shRNA. More importantly, reduction in p21 expression in MSCs enhanced the bone repair capacity of MSCs in a rodent calvarial defect model. Knockdown of p21 in MSCs also increased the telomerase activity and telomere length, and did not show chromosomal abnormalities or acquire transformation ability. Therefore, these data successfully demonstrate the involvement of senescence gene in the expression of stemness markers and osteogenic potential of MSCs.

ObjectiveTo analyze the efficacy of gemcitabine with or without erlotinib for pancreatic cancer, and to determine the predictive role of epidermal growth factor receptor (EGFR) and KRAS mutations in these patients.MethodsThis was a single-center, randomized, open-label, prospective trial. Eighty-eight chemotherapy-naïve metastatic pancreatic cancer patients were randomized for treatment with gemcitabine or gemcitabine plus erlotinib. EGFR and KRAS mutations were analyzed, respectively. The primary endpoint was the disease control rate.ResultsDisease control rate (64% vs. 25%; P < 0.001), progression-free survival (median 3.8 vs. 2.4 months; P < 0.001), and overall survival (median 7.2 vs. 4.4 months; P < 0.001) were better in the gemcitabine plus erlotinib group than in the gemcitabine alone group. In the gemcitabine plus erlotinib group, disease control (85% vs. 33%; P = 0.001), progression-free survival (median 5.9 vs. 2.4 months; P = 0.004), and overall survival (median 8.7 vs. 6.0 months; P = 0.044) were better in patients with EGFR mutations than in those without EGFR mutations. KRAS mutation was not associated with treatment response or survival.ConclusionsGemcitabine plus erlotinib is more effective than gemcitabine alone for treating metastatic pancreatic cancer patients, especially those with EGFR mutations. ClinicalTrials.gov number, NCT01608841.

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