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Hemizygous deletion of 17p13, which harbors the TP53 gene, has been identified in >10% of newly diagnosed multiple myeloma (MM) patients and is associated with poor prognosis. To date, there is no conclusive evidence that TP53 is the critical gene. Furthermore, the functional effect of TP53 haploinsufficiency is not well characterized. By utilizing human myeloma cell lines, we showed that TP53 hemizygous loss was associated with decreased basal expression level with a partially or severely inactivated p53 response upon genotoxic and non-genotoxic stress. The pathway deficiency was manifested as defective p53 transcriptional activities, together with significant resistance to apoptosis. In some cases with p53 WT/- and no p53 protein expression, the remaining allele was silenced by promoter hypermethylation. We also developed a p53 target gene signature to summarize the complexity of the p53 pathway abnormalities in MM and showed that it is strongly associated with genomic complexity and patient survival. In conclusion, this study identified TP53 as the critical gene located in 17p13, and revealed its haploinsufficiency properties in MM. Furthermore, we have elucidated that multiple mechanisms can deregulate the p53 functions and that this has important prognostic impact in MM.

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Key Points IMiDs inhibit TrxR-mediated intracellular decomposition of H2O2 and caused oxidative stress in MM cells. MM cells with lower antioxidative capacity were more vulnerable to lenalidomide-induced H2O2 accumulation and its associated cytotoxicity.

Although relatively good therapeutic results are achieved in non-advanced cancer, the prognosis of the advanced colon cancer still remains poor, dependent on local or distant recurrence of the disease. One of the factors responsible for recurrence is supposed to be cancer stem cells (CSCs) or tumor-initiating cells, which are a population of cancer cells with ability to perpetuate themselves through self-renewal and to generate differentiated cells, thought to be responsible for tumor recurrence. This study globally approach the possible role of tissue-derived stem cells in the initiation of colon cancer and its metastatic process in the liver. Fresh surgical specimens from colon cancer, non-tumor tissue and liver metastasis were obtained directly from the operating room, examined, and immediately processed. CSCs were selected under serum-free conditions and characterized by CD44 and CD133 expression levels. CD133þ /CD44 þ cell populations were then investigated in paraffin-embedded tissues and circulating tumor cells isolated from peripheral blood of the same group of colon cancer patients. Our data demonstrate that metastatic properties of cell populations from blood and liver metastasis, differently from primitive tumors, seem to be strictly related to the phenotype CD133 positive and CD44 positive.J. Cell. Physiol. 228: 408-415, 2013. ß 2012 Colon cancer is the second leading cause of cancer-related death. The majority of these deaths are due to metastasis, with the liver easily the most common site of deposit (LeGolvan and Resnick, 2010). Combining surgery and chemotherapy in the treatment of patients with colon hepatic metastases is increasingly becoming the standard of care. However, controversy remains regarding the juxtapositioning of chemotherapy and surgery, the duration of chemotherapy, and particularly, the use of preoperative chemotherapy in the treatment of patients with initially resectable metastases (Nordlinger et al., 2010).Cancer metastasis has been explained by at least two models: a progression model and an initiating model. In the former, metastatic capacity is acquired during cancer progression in a subpopulation of cells through sequential genetic mutations or epigenetic alterations (Gray, 2010), in genes associated with proteolysis of local extracellular matrix attachments (Nagashima et al., 1997), adhesive alterations (Furger et al., 2001), angiogenesis (Weber, 2008), viable vascular dissemination, distant embolization, and survival in a new environment (Folkman, 1990;Hynes, 2003;Bird et al., 2006). However, not all of these genetic alterations occur during the process of liver metastasis (Gray, 2010). In the initiation model, cells with metastatic potential are determined by early mutational events in a progenitor cell, named cancer stem cell (CSCs) or tumor-initiating cells (TIC; Clarke and Fuller, 2006;Polyak and Hahn, 2006;Odoux et al., 2008), even if few data support the hypothesis of its role in the colon metastatic process in humans (Horst et al., 2009b;Puglisi et al., 2009;Ju e...