Angiogenesis is an early event in the development of chemically induced skin tumors

In this study we have analyzed the vascular response induced in the two- stage carcinogenesis model in SENCAR mice. The role of angiogenesis has not been explored in this model, which is the paradigm of multistage carcinogenesis and a model for neoplastic lesions derived from exophytic premalignant lesions (e.g. colon carcinoma, bladder papilloma). We investigated if angiogenesis is involved in the formation of papillomas and in the progression from papilloma to carcinoma. To this end we analyzed the vasculature of normal and hyperplastic skin, focal epidermal hyperplasias that are precursors of papillomas, papillomas at different stages and squamous cell carcinomas. We also analyzed the vascularization of papillomas induced in two strains of mice that differ in their susceptibility to malignant progression. We show here that angiogenesis is turned on in the earliest stages of papilloma formation. In late stages, regardless of state of progression, the predominant response is an increase in the size of blood vessels. Thus, in the SENCAR mouse model, representative of exophytic tumors, the angiogenesis switch is a very early event, probably mechanistically related to the development of the primarily exophytic lesions. Therefore, the density of blood vessels cannot be used as a predictor of malignant progression in this model.      

MRI characteristics of the neurocentral synchondrosis

BACKGROUND AND OBJECTIVES: The neurocentral synchondrosis (NCS) is a cartilaginous growth plate that since the early 1900s has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS). Previous studies have focused only on the closure age without characterizing normal NCS development. Using MRI, the normal development of the NCS image can be characterized, and the stages preceding the disappearance of this image can be specified. METHODS: A total of 405 NCSs were visualized in 11 normal pediatric patients using T1 and T2 transverse and sagittal MRI views. The images were correlated and the variety of images recorded to categorize the NCS into developmental stages. RESULTS: The development of the NCS was categorized into five developmental stages. The image of the NCS became absent in a specific pattern along the vertebral column, first in the cervical region (age 6), then in the lumbar region (age 12), and finally in the thoracic region (age 14). CONCLUSION: The normal development of the NCS at the level of individual vertebrae and also along the vertebral column as a whole was determined using MRI. These patterns of development are valuable and necessary to evaluate the role of the NCS in pathological conditions.     

Surveillance of γδ T Cells Predicts Cytomegalovirus Infection Resolution in Kidney Transplants

Cytomegalovirus (CMV) infection in solid-organ transplantation is associated with increased morbidity and mortality, particularly if a CMV mutant strain with antiviral resistance emerges. Monitoring CMV–specific T cell response could provide relevant information for patient care. We and others have shown the involvement of Vδ2^neg γδ T cells in controlling CMV infection. Here, we assessed if Vδ2^neg γδ T cell kinetics in peripheral blood predict CMV infection resolution and emergence of a mutant strain in high–risk recipients of kidney transplants, including 168 seronegative recipients receiving organs from seropositive donors (D+R−) and 104 seropositive recipients receiving antithymocyte globulins (R+/ATG). Vδ2^neg γδ T cell percentages were serially determined in patients grafted between 2003 and 2011. The growing phase of Vδ2^neg γδ T cells was monitored in each infected patient, and the expansion rate during this phase was estimated individually by a linear mixed model. A Vδ2^neg γδ T cell expansion rate of ˃0.06% per day predicted the growing phase. The time after infection at which an expansion rate of 0.06% per day occurred was correlated with the resolution of CMV DNAemia (r=0.91; P<0.001). At 49 days of antiviral treatment, Vδ2^neg γδ T cell expansion onset was associated with recovery, whereas absence of expansion was associated with recurrent disease and DNAemia. The appearance of antiviral–resistant mutant CMV strains was associated with delayed Vδ2^neg γδ T cell expansion (P<0.001). In conclusion, longitudinal surveillance of Vδ2^neg γδ T cells in recipients of kidney transplants may predict CMV infection resolution and antiviral drug resistance.     

Akt inhibition improves irinotecan treatment and prevents cell emergence by switching the senescence response to apoptosis

Activated in response to chemotherapy, senescence is a tumor suppressive mechanism that induces a permanent loss of proliferation. However, in response to treatment, it is not really known how cells can escape senescence and how irreversible or incomplete this pathway is. We have recently described that cells that escape senescence are more transformed than non-treated parental cells, they resist anoikis and rely on Mcl-1. In this study, we further characterize this emergence in response to irinotecan, a first line treatment used in colorectal cancer. Our results indicate that Akt was activated as a feedback pathway during the early step of senescence. The inhibition of the kinase prevented cell emergence and improved treatment efficacy, both in vitro and in vivo. This improvement was correlated with senescence inhibition, p21waf1 downregulation and a concomitant activation of apoptosis due to Noxa upregulation and Mcl-1 inactivation. The inactivation of Noxa prevented apoptosis and increased the number of emergent cells. Using either RNA interference or p21waf1-deficient cells, we further confirmed that an intact p53-p21-senescence pathway favored cell emergence and that its downregulation improved treatment efficacy through apoptosis induction. Therefore, although senescence is an efficient suppressive mechanism, it also generates more aggressive cells as a consequence of apoptosis inhibition. We therefore propose that senescence-inducing therapies should be used sequentially with drugs favoring cell death such as Akt inhibitors. This should reduce cell emergence and tumor relapse through a combined induction of senescence and apoptosis.     

Autocrine insulin-like growth factor 1 and stem cell factor but not interleukin 6 support self-renewal of human myeloma cells

In this study, we have identified the growth factors supporting myeloma self-renewal in eight myeloma cell lines. All cell lines able to form self-colonies displayed constitutive P-AKT and P-ERK1,2 but not P-STAT3 and did not express CD45, suggesting the presence of an insulin-like growth factor 1 (IGF1) loop. We showed that a blocking anti-insulin-like growth factor 1 receptor (IGF1R) monoclonal antibody (mAb) inhibited colony formation in correlation with IGF1R expression and decreased P-AKT. Imatinib or a blocking anti-stem cell factor (SCF) mAb also inhibited colony formation of two cell lines expressing C-KIT and SCF, and decreased P-AKT. Moreover, the PI3K/AKT pathway inhibitor wortmannin inhibited colony formation. Blocking interleukin (IL)6R did not inhibit colony formation in good agreement with a lack of constitutive P-STAT3. We showed that primary cells frequently co-expressed IGF1R/IGF1 but not C-KIT/SCF or IL6R/IL6, suggesting that in vivo autonomous growth could be possible via IGF1R. Despite their similar role in clonogenic growth and shared signaling pathway, IGF1R and C-KIT had opposite prognostic values, suggesting that they were surrogate markers. Indeed, we showed that both C-KIT and IGF1R prognostic values were not independent of MMSET expression. This study highlights the autocrine role of IGF1 in myeloma cells and reinforces the interest in targeting IGF1R in IGFR1⁺ CD45^+/− patients, such as MMSET⁺ patients.