Induction of alkylator (melphalan) resistance in HL60 cells is accompanied by increased levels of topoisomerase II expression and function

The snoRNA target of t(4;14) in multiple myeloma regulates ribosome biogenesis

The orphan small nucleolar RNA (snoRNA) ACA11 is overexpressed as a result of the t(4;14) chromosomal translocation in multiple myeloma (MM), increases reactive oxygen species, and drives cell proliferation. Like other snoRNAs, ACA11 is predominantly localized to a sub-nuclear organelle, the nucleolus. We hypothesized that increased ACA11 expression would increase ribosome biogenesis and protein synthesis. We found that ACA11 overexpression in MM cells increased nucleolar area and number as well as silver-binding nucleolar organizing regions (AgNORs). Supporting these data, samples from t(4;14)-positive patients had higher AgNORs scores than t(4;14)-negative samples. ACA11 also upregulated ribosome production, pre-47S rRNA synthesis, and protein synthesis in a ROS-dependent manner. Lastly, ACA11 overexpression enhanced the response to proteasome inhibitor in MM cells, while no effect was found in response to high doses of melphalan. Together, these data demonstrate that ACA11 stimulates ribosome biogenesis and influences responses to chemotherapy. ACA11 may be a useful target to individualize the treatment for t(4;14)-positive myeloma patients.

Upregulation of multi drug resistance genes in doxorubicin resistant human acute myelogeneous leukemia cells and reversal of the resistance

The major problem in the treatment of acute myeloid leukemia (AML) patients results from multidrug resistance to administered anticancer agents. Drug resistance proteins, MDR1 and MRP1, which work as drug efflux pumps, can mediate the multidrug resistance of human leukemia cells. In this study, the mechanisms of resistance to doxorubicin-induced cell death in human HL60 AML cells were examined. Continuous exposure of cells to step-wise increasing concentrations of doxorubicin resulted in the selection of HL60/DOX cells, which expressed about 10.7-fold resistance as compared to parental sensitive cells. The expression analyses of MRP1 and MDR1 drug efflux proteins in doxorubicin-sensitive and -resistant HL60 cells revealed that there was an upregulation of MRP1 gene in HL60/DOX cells as compared to parental sensitive cells. On the other hand, while there was no expression of MDR1 gene in parental cells, the expression of MDR1 gene was upregulated in HL60/DOX cells. HL60/DOX cells also showed cross-resistance to cytosine arabinoside (Ara-c). This resistance was reversed by a combination therapy of Ara-c and cyclosporine A. However, the expression levels of CD15 and CD16 surface markers were significantly decreased in HL60/DOX cells.

Pharmacokinetics & drug resistance of melphalan in regional chemotherapy: ILP versus ILI

Two forms of regional chemotherapy for the treatment of advanced melanoma or sarcoma of the extremity are isolated limb perfusion (ILP) and the more recently described isolated limb infusion (ILI). Melphalan is the most commonly employed agent in both ILP and ILI, although it is often used in conjunction with other cytotoxic and/or biologic therapies. While ILP and ILI are far more effective for the treatment of extremity disease than is systemic therapy, there is still significant room for improvement in outcomes, from the standpoint of both response rate and toxicity. An understanding of the pharmacokinetics of regional chemotherapy would allow for the prediction of tumor response and toxicity and therefore patient outcomes. In addition, elucidating the mechanisms of drug resistance would lead to opportunities to develop effective chemo-modulators that enhance the effectiveness of ILP and ILI. This paper reviews progress in these two key areas of active investigation.

American Society of Clinical Oncology 2007 update of recommendations for the use of tumor markers in breast cancer

PURPOSE

To update the recommendations for the use of tumor marker tests in the prevention, screening, treatment, and surveillance of breast cancer.

METHODS

For the 2007 update, an Update Committee composed of members from the full Panel was formed to complete the review and analysis of data published since 1999. Computerized literature searches of MEDLINE and the Cochrane Collaboration Library were performed. The Update Committee's literature review focused attention on available systematic reviews and meta-analyses of published tumor marker studies. In general, significant health outcomes (overall survival, disease-free survival, quality of life, lesser toxicity, and cost-effectiveness) were used for making recommendations. Recommendations and

CONCLUSIONS

Thirteen categories of breast tumor markers were considered, six of which were new for the guideline. The following categories showed evidence of clinical utility and were recommended for use in practice: CA 15-3, CA 27.29, carcinoembryonic antigen, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, urokinase plasminogen activator, plasminogen activator inhibitor 1, and certain multiparameter gene expression assays. Not all applications for these markers were supported, however. The following categories demonstrated insufficient evidence to support routine use in clinical practice: DNA/ploidy by flow cytometry, p53, cathepsin D, cyclin E, proteomics, certain multiparameter assays, detection of bone marrow micrometastases, and circulating tumor cells.

The FA/BRCA pathway is involved in melphalan-induced DNA interstrand cross-link repair and accounts for melphalan resistance in multiple myeloma cells

Melphalan, a DNA cross-linker, is one of the most widely used and effective drugs in the treatment of multiple myeloma (MM). In this report, we demonstrate that enhanced interstrand cross-link (ICL) repair via the Fanconi anemia (FA)/BRCA pathway contributes to acquired drug resistance in melphalan-resistant myeloma cell lines, and disruption of this pathway reverses drug resistance. Using the alkaline comet assay (single-cell gel electrophoresis), we observed that melphalan-resistant cells have reduced ICL formation and enhanced ICL repair compared with melphalan-sensitive cells. Cell-cycle studies demonstrated that enhanced ICL repair released cells from melphalan-induced cell-cycle delay. Using siRNA to knock down FANCF in 8226/LR5 and U266/LR6 drug-resistant cells demonstrated a direct relationship between ICL repair capacity and drug sensitivity. Overexpression of FANCF in 8226/S and U266/S drug-sensitive cells partially reproduced the drug-resistant phenotype. These data show that enhanced DNA repair via the Fanconi anemia/BRCA pathway is involved in acquired melphalan resistance. Our findings provide for a new target to enhance response to DNA cross-linking agents in cancer treatment.

Caspase-11 is not necessary for chemotherapy-induced intestinal mucositis

Mucositis is a common, dose-limiting toxicity associated with drug and radiation therapy for cancer. The ulcerative lesions of mucositis serve as systemic portals of entry for the micro-organisms that inhabit the mucosa of the gastrointestinal tract and the oral cavity, often leading to systemic infection. The pathogenesis of mucositis is complex, and consists of varying, sequential interactions between pro-inflammatory cytokines, transcription factors, and pro-apoptotic pathways of the mucosal epithelium and the cells and tissues within the submucosa. A possible mechanism for mucositis injury is the activation of caspases, a family of cysteine proteases. Caspase-11, one of 14 members of this enzymatic family, was studied to determine its role in the development of intestinal mucositis after exposure to melphalan in caspase-11 wild-type (+/+) and knockout (-/-) mice. Immunoblots demonstrated the activation of caspase-11 in duodenal and jejunal samples 24 and 48 h after melphalan administration. No significant differences in the level of intestinal cell death or macrophage infiltration, as measured by TUNEL staining and immunohistochemistry, were present between wildtype (+/+) and knockout (-/-) mice. These findings suggest that while caspase-11 activation occurs in response to melphalan, it does not have a primary role in the pathogenesis of intestinal mucositis.

The HER2 extracellular domain as a prognostic and predictive factor in breast cancer

The HER2/neu proto-oncogene encodes a 185-kd transmembrane receptor with tyrosine kinase activity. Amplification of HER2 with overexpression of the p185HER2 receptor occurs in 20%-30% of breast cancers and has been established as an independent prognostic factor in numerous studies. Increasing evidence suggests that HER2 may be a predictive marker for response to chemotherapy and hormonal therapy. HER2 overexpression has provided a new target in breast cancer therapy, as evidenced by the development of trastuzumab (Herceptin(R)), a monoclonal antibody targeted against HER2. Detection of HER2 in the clinical setting is performed by immunohistochemistry or fluorescence in situ hybridization in tissue, and by detection of the shed extracellular domain in serum or plasma. Differences in methodology, reagents, and scoring systems have led to varying results in different patient cohorts, contributing to the debate on the role of HER2 as a prognostic and predictive factor. This review focuses on the prognostic and predictive value of serum HER2 detection in the management of HER2-positive breast cancer.