The mouse skin carcinogenesis protocol is a unique model for understanding the molecular events leading to oncogenic transformation. Mutations in the Ha-ras gene, and the presence of functional cyclin D1 and the EGF receptor, have proven to be important in this system. However, the signal transduction pathways connecting these elements during mouse skin carcinogenesis are poorly understood. This paper studies the relevance of the Akt and ERK pathways in the di erent stages of chemically induced mouse skin tumors. Akt activity increases throughout the entire process, and its early activation is detected prior to increased cyclin D1 expression. ERK activity rises only during the later stages of malignant conversion. The observed early increase in Akt activity appears to be due to raised PI-3K activity. Other factors acting on Akt such as ILK activation and decreased PTEN phosphatase activity appear to be involved at the conversion stage. To further con®rm the involvement of Akt in this process, PB keratinocytes were transfected with Akt and subsequently injected into nude mice. The expression of Akt accelerates tumorigenesis and contributes to increased malignancy of these keratinocytes as demonstrated by the rate of appearance, the growth and the histological characteristics of the tumors. Collectively, these data provide evidence that Akt activation is one of the key elements during the di erent steps of mouse skin tumorigenesis.

Most drugs currently used for human therapy interact with proteins, altering their activity to modulate the pathological cell physiology. In contrast, 2-hydroxy-9-cis-octadecenoic acid (Minerval) was designed to modify the lipid organization of the membrane. Its structure was deduced following the guidelines of the mechanism of action previously proposed by us for certain antitumor drugs. The antiproliferative activity of Minerval supports the above-mentioned hypothesis. This molecule augments the propensity of membrane lipids to organize into nonlamellar (hexagonal H II ) phases, promoting the subsequent recruitment of protein kinase C (PKC) to the cell membrane. The binding of the enzyme to membranes was marked and significantly elevated by Minerval in model (liposomes) and cell (A549) membranes and in heart membranes from animals treated with this drug. In addition, Minerval induced increased PKC␣ expression (mRNA and protein levels) in A549 cells. This drug also induced PKC activation, which led to a p53-independent increase in p21 CIP expression, followed by a decrease in the cellular concentrations of cyclins A, B, and D3 and cdk2. These molecular changes impaired the cell cycle progression of A549 cells. At the cellular and physiological level, administration of Minerval inhibited the growth of cancer cells and exerted antitumor effects in animal models of cancer without apparent histological toxicity. The present results support the potential use of Minerval and related compounds in the treatment of tumor pathologies.

GEMOX-R is a new salvage regimen for DLCL with high activity and relatively safe toxicity profile, which can be offered to elderly patients not candidates of ASCT consolidation. The high efficacy of the regimen in this unfavorable population and also in immunocompromised situations warrant further investigation of this regimen in all salvage situations of this type of lymphomas.

In mammalian cells, cell cycle withdrawal is a prerequisite for terminal differentiation. Accordingly, in most tissues, including epidermis, the expression of the cyclindependent kinase inhibitors increases during differentiation. However, the actual role of cyclin-dependent kinase inhibitors is unclear. Different aspects of epidermal growth and differentiation in ink4a ⌬2,3 -null, p21-null, and ink4a ⌬2,3 /p21-doubly deficient mice were studied. Altered differentiation and decreased age-related senescence were found in the epidermis of ink4a ⌬2,3 /p21-null mice and, to a lesser extent, in ink4a ⌬2,3 -and p21-null mice. ink4a ⌬2,3 /p21-null primary keratinocytes underwent cell cycle arrest upon calcium or transforming growth factor-␤ treatment, but failed to differentiate. This differentiation deficiency was not observed in p21-or ink4a ⌬2,3 -deficient keratinocytes. Upon infection with a v-Ha-ras-coding retrovirus, wild-type keratinocytes displayed features indicative of premature cell senescence. In p21-or ink4a ⌬2,3 -deficient keratinocytes, only a partial response was observed. ink4a ⌬2,3 /p21-deficient keratinocytes did not display senescent features, but showed increased tumorigenic potential upon injection into nude mice. These results indicate that ink4a/ arf and cip1/waf genes cooperate to allow normal keratinocyte differentiation and that the absence of both favors malignant transformation.

We report the long-term evaluation over 12 years of a simplified technique for stemcell cryopreservation at -80ºC without rate-controlled freezing and with 5% (n=251) or 10% (n=47) DMSO as the sole cryoprotectant. Platelet recovery was greater in the 5% DMSO group while long-term hematologic recovery did not differ. Factors influencing a faster hematologic recovery were infusion of more than 2.7×10 6 /kg of CD34 + cells, 10% DMSO cryopreservation and G-CSF. We confirm that the procedure is feasible with a reduction in infusion-related toxicity from 60% using 5% DMSO. Differences in hematologic reconstitution were not clinically significant if a minimum of 1. 1 The toxic effects related to DMSO infusion are generally dose-related and while they are usually mild, they can become severe.2-4 HES is a relatively non-toxic drug but it is related with long-lasting pruritus 5 and osmotic nephrotoxicity. Cryopreservation protocols usually involve ratecontrolled freezing followed by the storage of the HSC in either the liquid or vapor phase of liquid nitrogen. These procedures are time consuming and require expensive computerassisted devices.

Minerval is an oleic acid synthetic analogue that impairs lung cancer (A549) cell proliferation upon modulation of the plasma membrane lipid structure and subsequent regulation of protein kinase C localization and activity. However, this mechanism does not fully explain the regression of tumours induced by this drug in animal models of cancer. Here we show that Minerval also induced apoptosis in Jurkat T-lymphoblastic leukaemia and other cancer cells. Minerval inhibited proliferation of Jurkat cells, concomitant with a decrease of cyclin D3 and cdk2 (cyclin-dependent kinase2). In addition, the changes that induced on Jurkat cell membrane organization caused clustering (capping) of the death receptor Fas (CD95), caspase-8 activation and initiation of the extrinsic apoptosis pathway, which finally resulted in programmed cell death. The present results suggest that the intrinsic pathway (associated with caspase-9 function) was activated downstream by caspase-8. In a xenograft model of human leukaemia, Minerval also inhibited tumour progression and induced tumour cell death. Studies carried out in a wide variety of cancer cell types demonstrated that apoptosis was the main molecular mechanism triggered by Minerval. This is the first report on the pro-apoptotic activity of Minerval, and in part explains the effectiveness of this non-toxic anticancer drug and its wide spectrum against different types of cancer.

No abstract

No abstract