Catherine P. Leith

Bortezomib-resistant nuclear factor-kappaB activity in multiple myeloma cells.

Bortezomib (Velcade/PS341), a proteasome inhibitor used in the treatment of multiple myeloma (MM), can inhibit activation of nuclear factor-κB (NF-κB), a family of transcription factors often deregulated and constitutively activated in primary MM cells. NF-κB can be activated via several distinct mechanisms, including the proteasome inhibitor–resistant (PIR) pathway. It remains unknown what fraction of primary MM cells harbor constitutive NF-κB activity maintained by proteasome-dependent mechanisms. Here, we report an unexpected finding that constitutive NF-κB activity in 10 of 14 primary MM samples analyzed is refractory to inhibition by bortezomib. Moreover, when MM cells were cocultured with MM patient-derived bone marrow stromal cells (BMSC), microenvironment components critical for MM growth and survival, further increases in NF-κB activity were observed that were also refractory to bortezomib. Similarly, MM-BMSCs caused PIR NF-κB activation in the RPMI8226 MM cell line, leading to increased NF-κB–dependent transcription and resistance to bortezomib-induced apoptosis. Our findings show that primary MM cells frequently harbor PIR NF-κB activity that is further enhanced by the presence of patient-derived BMSCs. They also suggest that this activity is likely relevant to the drug resistance development in some patients. Further elucidation of the mechanism of PIR NF-κB regulation could lead to the identification of novel diagnostic biomarkers and/or therapeutic targets for MM treatment. (Mol Cancer Res 2008;6(8):1356–64)

Bortezomib-Resistant Nuclear Factor-κB Activity in Multiple Myeloma Cells

Bortezomib (Velcade/PS341), a proteasome inhibitor used in the treatment of multiple myeloma (MM), can inhibit activation of nuclear factor-κB (NF-κB), a family of transcription factors often deregulated and constitutively activated in primary MM cells. NF-κB can be activated via several distinct mechanisms, including the proteasome inhibitor–resistant (PIR) pathway. It remains unknown what fraction of primary MM cells harbor constitutive NF-κB activity maintained by proteasome-dependent mechanisms. Here, we report an unexpected finding that constitutive NF-κB activity in 10 of 14 primary MM samples analyzed is refractory to inhibition by bortezomib. Moreover, when MM cells were cocultured with MM patient-derived bone marrow stromal cells (BMSC), microenvironment components critical for MM growth and survival, further increases in NF-κB activity were observed that were also refractory to bortezomib. Similarly, MM-BMSCs caused PIR NF-κB activation in the RPMI8226 MM cell line, leading to increased NF-κB–dependent transcription and resistance to bortezomib-induced apoptosis. Our findings show that primary MM cells frequently harbor PIR NF-κB activity that is further enhanced by the presence of patient-derived BMSCs. They also suggest that this activity is likely relevant to the drug resistance development in some patients. Further elucidation of the mechanism of PIR NF-κB regulation could lead to the identification of novel diagnostic biomarkers and/or therapeutic targets for MM treatment. (Mol Cancer Res 2008;6(8):1356–64)

Bone marrow stromal cells from multiple myeloma patients uniquely induce bortezomib resistant NF-κB activity in myeloma cells

BackgroundComponents of the microenvironment such as bone marrow stromal cells (BMSCs) are well known to support multiple myeloma (MM) disease progression and resistance to chemotherapy including the proteasome inhibitor bortezomib. However, functional distinctions between BMSCs in MM patients and those in disease-free marrow are not completely understood. We and other investigators have recently reported that NF-κB activity in primary MM cells is largely resistant to the proteasome inhibitor bortezomib, and that further enhancement of NF-κB by BMSCs is similarly resistant to bortezomib and may mediate resistance to this therapy. The mediating factor(s) of this bortezomib-resistant NF-κB activity is induced by BMSCs is not currently understood.ResultsHere we report that BMSCs specifically derived from MM patients are capable of further activating bortezomib-resistant NF-κB activity in MM cells. This induced activity is mediated by soluble proteinaceous factors secreted by MM BMSCs. Among the multiple factors evaluated, interleukin-8 was secreted by BMSCs from MM patients at significantly higher levels compared to those from non-MM sources, and we found that IL-8 contributes to BMSC-induced NF-κB activity.ConclusionsBMSCs from MM patients uniquely enhance constitutive NF-κB activity in MM cells via a proteinaceous secreted factor in part in conjunction with IL-8. Since NF-κB is known to potentiate MM cell survival and confer resistance to drugs including bortezomib, further identification of the NF-κB activating factors produced specifically by MM-derived BMSCs may provide a novel biomarker and/or drug target for the treatment of this commonly fatal disease.

Overexpression of Protein Kinase C-ε in the Mouse Epidermis Leads to a Spontaneous Myeloproliferative-Like Disease

Protein kinase C (PKC)-e, a Ca 2+ -independent, phospholipid-dependent serine/threonine kinase, is among the PKC isoforms expressed in mouse epidermis. We reported that FVB/N transgenic mouse lines that overexpress (8- or 18-fold) PKC-e protein in basal epidermal cells and cells of the hair follicle develop papilloma-independent squamous cell carcinoma (SCC) elicited by 7,12-dimethylbenz(a)anthracene initiation and 12-O-tetradecanoylphorbol-13-acetate-promotion or by repeated ultraviolet radiation exposures. The susceptibility to the development of SCC was proportional to the level of expression of the PKC-e transgene. We now report that PKC-e FVB/N transgenic mice (line 215) that overexpress in epidermis ∼18-fold PKC-e protein more than their wild-type littermates spontaneously develop a myeloproliferative-like disease (MPD) in 100% of PKC-e transgenic mice. The MPD was characterized by an excess of neutrophils and eosinophils, resulting in invasion of almost all vital organs of the mouse by 6 months of age. On gross examination these mice present with splenomegaly, hepatomegaly, and severe lymphadenopathy. Examination of the bone marrow revealed almost complete effacement by neutrophils, eosinophils, and their precursors. Furthermore, the spleen and lymph nodes were enlarged and exhibited marked extramedullary hematopoiesis. Complete pathological analysis of the second PKC-e transgenic mouse (line 224) that expresses approximately eightfold PKC-e protein more than their wild-type littermates revealed no remarkable findings in any of the affected organs as seen in line 215. However, peripheral blood analyses of PKC-e transgenic mice indicated significant increases of neutrophils in the circulating blood in both PKC-e transgenic lines. To determine whether there was an imbalance of cytokines in PKC-e transgenic mice (line 215), resulting in aberrant myelopoiesis, we analyzed 17 cytokines in the peripheral blood. This analysis indicated that interleukin-5, interleukin-6, and granulocyte-colony stimulating factor were up-regulated as a function of age. The transgene PKC-e was not detected in any of the affected organs (bone marrow, liver, spleen, lung) We suggest that overexpression of PKC-e in the epidermis may lead to the induction of specific cytokines that may, in a paracrine mechanism, perturb normal hematopoiesis in bone marrow resulting in a granulocytic skew toward that of neutrophils and eosinophils. The susceptibility of PKC-e transgenic mice to the induction of SCC and the spontaneous development of MPD are unrelated.

A phase I pharmacokinetic and pharmacodynamic correlative study of the antisense Bcl-2 oligonucleotide g3139, in combination with carboplatin and paclitaxel, in patients with advanced solid tumors.

Purpose: This phase I trial assessed the safety and tolerability of G3139 when given in combination with carboplatin and paclitaxel chemotherapy. The effect of G3139 treatment on Bcl-2 expression in peripheral blood mononuclear cells (PBMC) and paired tumor biopsies was also determined. Experimental Design: Patients with advanced solid malignancies received various doses of G3139 (continuous i.v. infusion days 1-7), carboplatin (day 4), and paclitaxel (day 4), repeated in 3-week cycles, in a standard cohort-of-three dose-escalation schema. Changes in Bcl-2/Bax transcription/expression were assessed at baseline and day 4 (prechemotherapy) in both PBMCs and paired tumor biopsies. The pharmacokinetic interactions between G3139 and carboplatin/paclitaxel were measured. Results: Forty-two patients were evaluable for safety analysis. Primary toxicities were hematologic (myelosuppression and thrombocytopenia). Dose escalation was stopped with G3139 at 7 mg/kg/d, carboplatin at area under the curve of 6, and paclitaxel at 175 mg/m2 due to significant neutropenia seen in cycle 1 and safety concerns in further escalating chemotherapy in this phase I population. With G3139 at 7 mg/kg/d, 13 patients underwent planned tumor biopsies, of which 12 matched pairs were obtained. Quantitative increases in intratumoral G3139 with decreases in intratumoral Bcl-2 gene expression were seen. This paralleled a decrease in Bcl-2 protein expression observed in PBMCs. Conclusions: Although the maximal tolerated dose was not reached, the observed toxicities were consistent with what one would expect from carboplatin and paclitaxel alone. In addition, we show that achievable intratumoral G3139 concentrations can result in Bcl-2 down-regulation in solid tumors and PBMCs.

Bortezomib-Resistant Nuclear Factor- B Activity in Multiple Myeloma Cells

Bortezomib (Velcade/PS341), a proteasome inhibitor used in the treatment of multiple myeloma (MM), can inhibit activation of nuclear factor-κB (NF-κB), a family of transcription factors often deregulated and constitutively activated in primary MM cells. NF-κB can be activated via several distinct mechanisms, including the proteasome inhibitor–resistant (PIR) pathway. It remains unknown what fraction of primary MM cells harbor constitutive NF-κB activity maintained by proteasome-dependent mechanisms. Here, we report an unexpected finding that constitutive NF-κB activity in 10 of 14 primary MM samples analyzed is refractory to inhibition by bortezomib. Moreover, when MM cells were cocultured with MM patient-derived bone marrow stromal cells (BMSC), microenvironment components critical for MM growth and survival, further increases in NF-κB activity were observed that were also refractory to bortezomib. Similarly, MM-BMSCs caused PIR NF-κB activation in the RPMI8226 MM cell line, leading to increased NF-κB–dependent transcription and resistance to bortezomib-induced apoptosis. Our findings show that primary MM cells frequently harbor PIR NF-κB activity that is further enhanced by the presence of patient-derived BMSCs. They also suggest that this activity is likely relevant to the drug resistance development in some patients. Further elucidation of the mechanism of PIR NF-κB regulation could lead to the identification of novel diagnostic biomarkers and/or therapeutic targets for MM treatment. (Mol Cancer Res 2008;6(8):1356–64)

Transmission of Babesia microti Parasites by Solid Organ Transplantation.

Infection with this parasite should be included in differential diagnosis of fever and anemia after blood transfusion or organ transplantation.

Kaposi sarcoma herpesvirus/human herpesvirus-8-negative effusion-based lymphoma: report of 3 cases and review of the literature.

Primary effusion lymphoma (PEL) is a rare subtype of large B‐cell lymphoma that arises in body cavities without detectable tumor masses. PEL is universally associated with Kaposi sarcoma herpesvirus (KSHV)/human herpesvirus‐8 (HHV8). Despite overlapping features, KSHV/HHV8‐negative effusion‐based lymphoma is a distinct entity from PEL. To date, 52 cases have been reported. The authors report 3 additional cases received in their laboratory from 2007 to 2012.

Value-Based Flow Testing of Chronic Lymphoproliferative Disorders A Quality Improvement Project to Develop an Algorithm to Streamline Testing and Reduce Costs

OBJECTIVES Flow cytometry is essential for the evaluation of lymphoproliferative disorders (LPDs) and their classification. Flow panels routinely incorporate a large array of antibodies, making testing complex and expensive; such panels are likely unnecessary in benign cases or those with straightforward diagnoses. Our aim was to develop a more cost-effective testing strategy based on a retrospective analysis of flow studies for possible LPDs in blood. METHODS We identified LPD frequencies and types, as well as associated results with patient age and absolute lymphocyte count. RESULTS We found that the likelihood of LPDs increased with patient age and absolute lymphocyte count and that CD5-positive LPD was the most common LPD diagnosed in our institution (71% of LPDs). Using these data, we devised flow-testing algorithms with a screening test for patients at low risk of disease and a focus on CD5-positive LPD detection, with reflexing as needed. CONCLUSIONS We project this approach will result in a 40% decrease in antibody utilization.

Use of Tissue Microarray and Automated Quantitative Analysis For Screening and Validation of Potential Biomarkers in Mantle Cell Lymphoma

BackgroundCancer biomarker studies using the combination of tissue microarray and automated quantitative assessment of immunofluorescence (TMA-AQUA) have been successfully performed for various types of human carcinoma, but its performance characteristics have yet to be evaluated in human lymphoma. MethodsA pilot TMA was constructed containing duplicate 1.5 mm cores from 15 cases of mantle cell lymphoma (MCL), 3 cases of low-grade B-cell lymphoma, and 3 cases of benign lymphoid tissue. Protein expression of c-Myc, Cdc2, Cyclin D1, Ki-67, Mcm2, and p27 by immunofluorescence and chromagenic staining were evaluated by AQUA and visual scoring, respectively. Gene expression of cMYC, CDC2, and CCND1 was determined by quantitative nuclease protection assay. ResultsProtein expression between duplicate cores determined by AQUA showed excellent correlation for all markers [correlation coefficient (R)=0.79 to 0.94] and Cyclin D1 expression was significantly higher in MCL cases compared with non-MCL cases (P=0.00019). Overall correlation of AQUA with scoring of chromagenic staining by 2 pathologists was good for all markers (R=0.56 to 0.90), except Cdc2 (R=0.25). Localization of expression to cytoplasmic and/or nuclear compartments was comparable with chromagenic staining patterns for all markers except Ki-67 and Mcm2, where a significant difference between nuclear and cytoplasmic expression could not be appreciated by AQUA, despite clear nuclear localization by chromagenic staining. Correlation of gene expression with protein expression was variable for CDC2, cMYC, and CCND1 (R=0.32, 0.35, and 0.69). ConclusionsTMA-AQUA has the potential to be successfully used as a high-throughput protein biomarker screening platform for MCL; however, appropriate target protein selection and antibody performance validation are factors that need to be considered.