Victoria Zismanov

Bronchoscopic balloon dilatation of tracheobronchial stenosis: long-term follow-up

OBJECTIVES Bronchoscopic balloon dilatation (BBD) has become a valuable tool in the treatment of tracheobronchial stenosis (TBS). The objective of this study was to assess the short- and long-term effects of BBD. METHODS A retrospective study that included all patients with confirmed, symptomatic stenosis, who underwent BBD between 2002 and 2008. A total of 92 BBD procedures were performed in 35 patients at our institute. Lung function studies were recorded for all patients before, immediately after and 1 month following the BBD. Long-term follow-up was for a mean of 33+/-4 months. RESULTS All patients had initial success, including increased airway dimensions and symptom relief. No complications were noted related to BBD. Forced expiratory volume after one second (FEV(1)) was significantly increased after BBD (10.5%, p=0.03). These effects persisted for at least 1 month. Long-term follow-up, however, demonstrated the need for stent placement in 25 of 35 patients (71%), 210+/-91 days after BBD. Ten of 35 patients died 456+/-119 days after BBD due to progression of primary disease; all deaths were unrelated to the BBD procedures. CONCLUSIONS BBD is a safe method that offers immediate symptomatic relief in both tracheal and bronchial stenosis. However, BBD is a temporary measure, as many patients will require definitive or additional treatment with laser or stent placement.

Bevacizumab attenuates major signaling cascades and eIF4E translation initiation factor in multiple myeloma cells

Multiple myeloma (MM), a malignancy of plasma cells, remains fatal despite introduction of novel therapies, partially due to humoral factors, including vascular endothelial growth factor (VEGF), in their microenvironment. The aim of this study was to explore the efficacy of anti-VEGF treatment with bevacizumab directly on MM cells. Particular attention was directed to the affect of VEGF inhibition on protein translation initiation. Experiments were conducted on MM cells (lines, bone marrow (BM) samples) cultured on plastic. Inhibition of VEGF was achieved with the clinically employed anti-VEGF antibody, bevacizumab, as a platform and its consequences on viability, proliferation, and survival was assessed. VEGF downstream signals of established importance to MM cell biology were assayed as well, with particular emphasis on translation initiation factor eIF4E. We showed that blocking VEGF is deleterious to the MM cells and causes cytostasis. This was evidenced in MM cell lines, as well as in primary BM samples (BM MM). A common bevacizumab-induced attenuation of critical signaling effectors was determined: VEGFR1, mTOR, c-Myc, Akt, STAT3, (cell lines) and eIF4E translation initiation factor (lines and BM). ERK1/2 displayed a variegated response to bevacizumab (lines). Utilizing a constitutively Akt-expressing MM model, we showed that the effect of bevacizumab on viability and eIF4E status is Akt-dependent. Of note, the effect of bevacizumab was achieved with high concentrations (2 mg/ml), but was shown to be specific. These findings demonstrate that bevacizumab has a direct influence on major pathways critically activated in MM that is independent from its established effect on angiogenesis. The cytostatic effect of VEGF inhibition on MM cells underscores its potential in combined therapy, and our findings, regarding its influence on translation initiation, suggest that drugs that unbalance cellular proteostasis may be particularly effective.

Multiple myeloma and bone marrow mesenchymal stem cells’ crosstalk: Effect on translation initiation

Multiple myeloma (MM) malignant plasma cells reside in the bone marrow (BM) and convert it into a specialized pre‐neoplastic niche that promotes the proliferation and survival of the cancer cells. BM resident mesenchymal stem cells (BM‐MSCs) are altered in MM and in vitro studies indicate their transformation by MM proximity is within hours. The response time frame suggested that protein translation may be implicated. Thus, we assembled a co‐culture model of MM cell lines with MSCs from normal donors (ND) and MM patients to test our hypothesis. The cell lines (U266, ARP‐1) and BM‐MSCs (ND, MM) were harvested separately after 72 h of co‐culture and assayed for proliferation, death, levels of major translation initiation factors (eIF4E, eIF4GI), their targets, and regulators. Significant changes were observed: BM‐MSCs (ND and MM) co‐cultured with MM cell lines displayed elevated proliferation and death as well as increased expression/activity of eIF4E/eIF4GI; MM cell lines co‐cultured with MM‐MSCs also displayed higher proliferation and death rates coupled with augmented translation initiation factors; in contrast, MM cell lines co‐cultured with ND‐MSCs did not display elevated proliferation only death and had no changes in eIF4GI levels/activity. eIF4E expression was increased in one of the cell lines. Our study demonstrates that there is direct dialogue between the MM and BM‐MSCs populations that includes translation initiation manipulation and critically affects cell fate. Future research should be aimed at identifying therapeutic targets that may be used to minimize the collateral damage to the cancer microenvironment and limit its recruitment into the malignant process.

Combined inhibition of Hsp90 and the proteasome affects NSCLC proteostasis and attenuates cell migration.

Lung cancer remains the most common cause of cancer-related death worldwide. This malignancy is a complex disease, and it is important to identify potential biological targets, the blockade of which would affect multiple downstream signaling cascades. A growing number of reports recognize novel therapeutic targets in the protein homeostasis network responsible for generating and protecting the protein fold. The heat shock protein 90 (Hsp90) is an essential molecular chaperon involved in the posttranslational folding and stability of proteins. It is required for conformational maturation of multiple oncogenic kinases that drive signal transduction and proliferation of cancer cells. However, in the case of unfolded protein accumulation endoplasmic reticulum (ER) stress is induced and several response pathways such as proteasome functions are activated. The ubiquitin–proteasome system orchestrates the turnover of innumerable cellular proteins. Here, we suggest that the therapeutic efficacy of Hsp90 inhibition may be augmented by coadministering proteasome inhibitor on human non-small-cell lung cancer (NSCLC) cell lines. Indeed, we showed that coadministration of the Hsp90 inhibitor 17-demethoxygeldanamycin (17-DMAG) and proteasome inhibitor (velcade) induced ER stress evidenced by increased unfolded protein response markers. The consequences were evident in multiple aspects of the NSCLC phenotype: reduced viability and cell count, increased apoptotic cell death, and most profoundly, synergistically decreased cell motility. Our findings provide proof-of-concept that targeting ER homeostasis is therapeutically beneficial in NSCLC cell lines.

Multiple myeloma proteostasis can be targeted via translation initiation factor eIF4E.

Intensive protein synthesis is a unique and differential trait of the multiple myeloma (MM) cells. Previously we showed that tetraspanin overexpression in MM cell lines attenuated mTOR and PI3K cascades, induced protein synthesis, activated unfolded protein response (UPR), and caused autophagic death, all suggesting breach of proteostasis. Here we assessed the role of translation initiation in the tetraspanin‑induced MM cell death with emphasis on eIF4E translation initiation factor. We showed tetraspanins attenuated peIF4E and its targets [c‑Myc, cyclin D1 (cycD1)]; eIF4E attenuation was Akt-dependent. eIF4E inhibition in MM cells [bone marrow (BM), lines] by siRNA and/or the anti‑viral drug and competitive eIF4E inhibitor ribavirin (RBV) deleteriously affected MM cells in a similar manner to the overexpression of tetraspanins. Furthermore, combined application of RBV and velcade had a synergistic anti‑MM effect. Our results demonstrate that breach of proteostasis via eIF4E inhibition is an attractive therapeutic approach that may be relatively easily achieved by employing RBV, making this strategy readily translatable into the clinic.

Multiple myeloma cells promote migration of bone marrow mesenchymal stem cells by altering their translation initiation

The role of the bone marrow microenvironment in multiple myeloma pathogenesis and progression is well recognized. Indeed, we have shown that coculture of bone marrow mesenchymal stem cells from normal donors and multiple myeloma cells comodulated translation initiation. Here, we characterized the timeline of mesenchymal stem cells conditioning by multiple myeloma cells, the persistence of this effect, and the consequences on cell phenotype. Normal donor mesenchymal stem cells were cocultured with multiple myeloma cell lines (U266, ARP1) (multiple myeloma–conditioned mesenchymal stem cells) (1.5 h,12 h, 24 h, 48 h, and 3 d) and were assayed for translation initiation status (eukaryotic translation initiation factor 4E; eukaryotic translation initiation factor 4G; regulators: mechanistic target of rapamycin, MNK, 4EBP; targets: SMAD family 5, nuclear factor κB, cyclin D1, hypoxia inducible factor 1, c‐Myc) (immunoblotting) and migration (scratch assay, inhibitors). Involvement of mitogen‐activated protein kinases in mesenchymal stem cell conditioning and altered migration was also tested (immunoblotting, inhibitors). Multiple myeloma–conditioned mesenchymal stem cells were recultured alone (1–7 d) and were assayed for translation initiation (immunoblotting). Quantitative polymerase chain reaction of extracted ribonucleic acid was tested for microRNAs levels. Mitogen‐activated protein kinases were activated within 1.5 h of coculture and were responsible for multiple myeloma–conditioned mesenchymal stem cell translation initiation status (an increase of >200%, P < 0.05) and elevated migration (16 h, an increase of >400%, P < 0.05). The bone marrow mesenchymal stem cells conditioned by multiple myeloma cells were reversible after only 1 d of multiple myeloma–conditioned mesenchymal stem cell culture alone. Decreased expression of microRNA‐199b and microRNA‐125a (an increase of <140%, P < 0.05) in multiple myeloma–conditioned mesenchymal stem cells supported elevated migration. The time‐ and proximity‐dependent conditioning of normal donor mesenchymal stem cells in our model points to a dynamic interaction between multiple myeloma cells and the bone marrow niche, which causes profound changes in the nonmalignant bone marrow constituents. Future studies are warranted to identify clinically relevant means of blocking this crosstalk and improving multiple myeloma therapy.

Letter to the Editor: miR‐199b‐3p and miR‐199a‐3p are isoforms with identical sequence and established function as tumor and metastasis suppressors

Letter to the Editor: miR-199b-3p and miR-199a-3p are isoforms with identical sequence and established function as tumor and metastasis suppressors M. Dabbah,* O. Attar-Schneider,* V. Zismanov,* S. Tartakover Matalon,* M. Lishner,* and L. Drucker* *Oncogenetic Laboratory and Internal Medicine Dept., Meir Medical Center, Kfar Saba, Israel; and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel