Neuroimaging signatures of cerebral small vessel disease and risk of falls in stroke-free older adults living in rural Ecuador. The Atahualpa Project.

PURPOSE: This study aimed to assess the association between neuroimaging signatures of cerebral small vessel disease (cSVD) and the risk of falls in stroke-free older adults living in rural Ecuador. METHODS: Risk of falls was evaluated by the Downton Fall Risk Index (DFRI). MRI readings focused on white matter hyperintensities (WMH) of presumed vascular origin, deep cerebral microbleeds (CMB), silent lacunar infarcts (LI), and > 10 enlarged basal ganglia-perivascular spaces (BG-PVS). Logistic regression models were fitted to evaluate whether these neuroimaging signatures were associated with the DFRI, after adjusting for relevant confounders. RESULTS: We included 288 participants. The DFRI was positive in 69 (24%). Moderate-to-severe WMH were noticed in 55 individuals (19%), deep CMB in 18 (6%), LI in 23 (8%), and > 10 BG-PVS in 65 (23%). Multivariate models showed a significant association between moderate-to-severe WMH and the DFRI (p = .016). There were no associations between other neuroimaging signatures of cSVD and the DFRI. Age was the single covariable remaining significant in all models. CONCLUSIONS: WMH is associated with the DFRI in stroke-free older adults living in a remote rural setting. A target for fall prevention should include the control of factors favoring the development of diffuse subcortical damage of vascular origin.

Prevalence, Severity, and Risk of Future Falls in Community-Dwelling Older Adults Living in a Rural Community: The Atahualpa Project.

Accidental falls are a leading cause of disability and death in older adults living in urban centers. However, little is known about the consequences of falls in rural communities. We aimed to assess characteristics and risk of falls in community-dwellers aged ≥ 60 years living in rural Ecuador. Of 463 older adults enrolled in the Atahualpa Project, 327 (71%) were included. Multivariate logistic regression models were fitted to assess factors associated with history of falls and risk of future falls. Sensitivity analysis was conducted to determine which component of the Downton fall risk index (DFRI) better predicts risk of future falls. A history of falls was reported by 173 (53%) individuals. Most were related to stumbling due to uneven (non-paved) streets. Only three individuals had bone fractures after the fall. Previous falls were not associated with any of the investigated covariables. The DFRI was positive in 87 (27%) participants, and was associated with age (p < 0.001) and history of stroke (p < 0.001). None of the subjects were taking tranquilizers/sedatives. The most reliable component of the DFRI was the presence of sensory/motor deficits. History of falls in our population is similar to that reported elsewhere. However, the risk of future falls is lower. Such discrepancies are probably because the DFRI does not take into account environmental factors resulting in falls. There were almost no severe complications from falls, which could be partly related to the lack of use of tranquilizers/sedatives.

Identification and editing of stem-like cells in methylcholanthrene-induced sarcomas.

The cancer stem cell (CSC) paradigm posits that specific cells within a tumor, so-called CSC-like cells, have differing levels of tumorigenicity and chemoresistance. Original studies of CSCs identified them in human cancers and utilized mouse xenograft models to define the cancer initiating properties of these cells, thereby hampering the understanding of how immunity could affect CSCs. Indeed, few studies have characterized CSCs in the context of cancer immunoediting, and it is currently not clear how immunity could impact on the levels or stem-like behavior of CSCs. Using the well-studied 3'methylcholanthrene (MCA) model of primary sarcoma formation, we have defined a CSC-like population within MCA-induced sarcomas as expressing high levels of stem cell antigen-1 (Sca-1) and low levels of CD90. These Sca-1+CD90- CSC-like cells had higher tumor initiating ability, could spontaneously give rise to Sca-1-negative cells, and formed more sarcospheres than corresponding non-CSC-like cells. Moreover, when examining MCA-induced sarcomas that were in the equilibrium phase of cancer growth, higher levels of CSC-like cells were found compared to MCA-induced sarcomas in the escape phase of cancer progression. Notably, CSC-like cells also emerged during escape from anti-PD-1 or anti-CTLA4 therapy, thus suggesting that CSC-like cells could evade immune therapy. Finally, we demonstrate that paradoxically, interferon (IFN)-γ produced in vivo by immune cells could promote the emergence of CSC-like cells. Our findings define the existence of a Sca1+CD90- CSC-like population in the MCA-sarcoma model capable of differentiation, tumorsphere formation, and increased tumor initiation in vivo. These cells may also act as mediators of immune resistance during cancer immunoediting and immune therapy.

eIF5A-PEAK1 Signaling Regulates YAP1/TAZ Protein Expression and Pancreatic Cancer Cell Growth.

In pancreatic ductal adenocarcinoma (PDAC), mutant KRAS stimulates the translation initiation factor eIF5A and upregulates the focal adhesion kinase PEAK1, which transmits integrin and growth factor signals mediated by the tumor microenvironment. Although eIF5A-PEAK1 signaling contributes to multiple aggressive cancer cell phenotypes, the downstream signaling processes that mediate these responses are uncharacterized. Through proteomics and informatic analyses of PEAK1-depleted PDAC cells, we defined protein translation, cytoskeleton organization, and cell-cycle regulatory pathways as major pathways controlled by PEAK1. Biochemical and functional studies revealed that the transcription factors YAP1 and TAZ are key targets of eIF5A-PEAK1 signaling. YAP1/TAZ coimmunoprecipitated with PEAK1. Interfering with eIF5A-PEAK1 signaling in PDAC cells inhibited YAP/TAZ protein expression, decreasing expression of stem cell-associated transcription factors (STF) including Oct4, Nanog, c-Myc, and TEAD, thereby decreasing three-dimensional (3D) tumor sphere growth. Conversely, amplified eIF5A-PEAK1 signaling increased YAP1/TAZ expression, increasing expression of STF and enhancing 3D tumor sphere growth. Informatic interrogation of mRNA sequence databases revealed upregulation of the eIF5A-PEAK1-YAP1-TEAD signaling module in PDAC patients. Taken together, our findings indicate that eIF5A-PEAK1-YAP signaling contributes to PDAC development by regulating an STF program associated with increased tumorigenicity. Cancer Res; 77(8); 1997-2007. ©2017 AACR.

Immunosurveillance and immunoediting in MMTV-PyMT-induced mammary oncogenesis.

Evidence of cancer immunosurveillance and immunoediting processes has been primarily demonstrated in mouse models of chemically induced oncogenesis. Although these models are very tractable, they are characterized by high mutational loads that represent a minority of human cancers. In this study, we sought to determine whether cancer immunosurveillance and immunoediting could be demonstrated in a more clinically relevant oncogene-induced model of carcinogenesis, the MMTV-PyMT (PyMT) mammary carcinoma model. This model system in the FVB/NJ strain background was previously used to demonstrate that adaptive immunity had no role in limiting primary cancer formation and in fact promoted metastasis, thus calling into question whether cancer immunosurveillance operated in preventing the development of breast cancer. Our current study in the C57BL/6 strain backgrounds provides a different conclusion, as we report here the existence of an adaptive immunosurveillance of PyMT mammary carcinomas using two independent models of immune deficiency. PyMT mice bred onto a Rag1-/- background or immune suppressed by chronic tacrolimus therapy both demonstrated accelerated development of mammary carcinomas. By generating a bank of cell lines from these animals, we further show that a subset of PyMT cell lines had delayed growth after transplantation into wild-type (WT) syngeneic, but not immune-deficient hosts. This reduced growth rate in immunocompetent animals was characterized by an increase in immune cell infiltration and tissue differentiation. Furthermore, loss of the immune cell infiltration that characterized immunoediting of slow growing cell lines, changed them into fast growing variants capable of progressing in the immunocompetent model. In conclusion, our study provides evidence that immunosurveillance and immunoediting of PyMT-derived cell lines modulate tumor progression in this oncogene-induced model of cancer.

The nuclear factor-κB pathway down-regulates expression of the NKG2D ligand H60a in vitro: implications for use of nuclear factor-κB inhibitors in cancer therapy.

NKG2D ligands are cell surface proteins that activate NKG2D, a receptor used by natural killer (NK) cells to detect virus-infected and transformed cells. When tumour cells express high levels of NKG2D ligands, they are rejected by the immune system. Hence, reagents that increase NKG2D ligand expression on tumour cells can be important for tumour immunotherapy. To identify genes that regulate the NKG2D ligand H60a, we performed a microarray analysis of 3'-methylcholanthrene-induced sarcoma cell lines expressing high versus low H60a levels. A20, an inhibitor of nuclear factor-κB (NF-κB) activation, was differentially expressed in H60a-hi sarcoma cells. Correspondingly, treatment of tumour cells with inhibitors of NF-κB activation, such as sulfasalazine (slz), BAY-11-7085, or a non-phosphorylatable IκB, led to increased levels of H60a protein, whereas transduction of cells with an active form of IκB kinase-ß (IKKß) led to decreased levels of H60a. The regulation probably occurred at the transcriptional level, because NF-κB pathway inhibition led to increased H60a transcripts and promoter activity. Moreover, treatment of tumour cells with slz enhanced their killing by NK cells in vitro, suggesting that NF-κB inhibition can lead to tumour cell rejection. Indeed, when we blocked the NF-κB pathway specifically in tumour cells, there was decreased tumour growth in wild-type but not immune-deficient mice. Our results suggest that reagents that can block NF-κB activity specifically in the tumour and not the host immune cells would be efficacious for tumour therapy.

Production of unique immunotoxin cancer therapeutics in algal chloroplasts.

The idea of targeted therapy, whereby drug or protein molecules are delivered to specific cells, is a compelling approach to treating disease. Immunotoxins are one such targeted therapeutic, consisting of an antibody domain for binding target cells and molecules of a toxin that inhibits the proliferation of the targeted cell. One major hurdle preventing these therapies from reaching the market has been the lack of a suitable production platform that allows the cost-effective production of these highly complex molecules. The chloroplast of the green alga Chlamydomonas reinhardtii has been shown to contain the machinery necessary to fold and assemble complex eukaryotic proteins. However, the translational apparatus of chloroplasts resembles that of a prokaryote, allowing them to accumulate eukaryotic toxins that otherwise would kill a eukaryotic host. Here we show expression and accumulation of monomeric and dimeric immunotoxin proteins in algal chloroplasts. These fusion proteins contain an antibody domain targeting CD22, a B-cell surface epitope, and the enzymatic domain of exotoxin A from Pseudomonas aeruginosa. We demonstrated that algal-produced immunotoxins accumulate as soluble and enzymatically active proteins that bind target B cells and efficiently kill them in vitro. We also show that treatment with either the mono- or dimeric immunotoxins significantly prolongs the survival of mice with implanted human B-cell tumors.