Bernard W Futscher

Bernard W Futscher

Assistant Research Scientist, Cancer Center Division
Associate Professor, BIO5 Institute
Investigator, Center for Toxicology
Professor, Pharmacology and Toxicology
Professor, Cancer Biology - GIDP
Primary Department
Department Affiliations
Contact
(520) 626-4646

Work Summary

Bernard Futscher's lab is studying the molecular origins of human cancer. Understanding epigenetic dysfunction in human cancer has been Dr. Futscher's primary research focus since establishing his own independent laboratory. This epigenetic research has moved into the area of noncoding RNAs and their potential role in cancer cell immortality.

Research Interest

Bernard Futscher, PhD, and his lab focus on the molecular origins of human cancer. More specifically, the lab group has 3 inter-related research objectives based on the underlying concept that developing an in-depth understanding of epigenetic mechanismsresponsible for governing cell fate will allow for the development of more effective strategies for the prevention, treatment, and cure of cancer. First, they wish to identify which epigenetic mechanisms participate in the transcriptional control of genes important to growth and differentiation. Second, they seek to determine how these epigenetic mechanisms, and therefore epigenetic homeostasis, become compromised during oncogenesis. Third, using a new and more complete understanding of epigenetic control of the genome, Dr. Futscher and his team are developing rational new therapeutic strategies that seek to repair these defects in the cancer cell and transcriptionally reprogram the malignant cancer cell to a benign state. To reach their objectives, a variety of in vitro models of cancer have been developed to address emerging hypotheses that are inferred from the literature in basic and clinical science as well as our own data. Results from these in vitro studies are then translated to the clinical situation to determine their meaning in the actual clinical face of the disease. Similarly, they attempt to take information obtained from the genome-wide assessment of clinical specimens in order to help guide our thinking and develop new hypotheses that can be tested experimentally in our in vitro models.

Publications

Abbaszadegan, M. R., Cress, A. E., Futscher, B. W., Bellamy, W. T., & Dalton, W. S. (1996). Evidence for cytoplasmic P-glycoprotein location associated with increased multidrug resistance and resistance to chemosensitizers. Cancer Research, 56(23), 5435-5442.

PMID: 8968098;Abstract:

A new human myeloma cell line, 8226/MDR10V, was selected from a P- glycoprotein-positive cell line, 8226/Dox40, in the continuous presence of doxorubicin and verapamil. MDR10V cells are 13-fold more resistant to doxorubicin and 4-fold more resistant to vincristine than the parent cell line, Dox40. Chemosensitizers are also less effective in reversing resistance in the MDR10V compared to the Dox40 cells. Despite higher resistance to cytotoxic agents, MDR10V expresses 40% less P-glycoprotein in the plasma membrane compared to Dox40; however, total cellular P- glycoprotein is the same in both cell lines. Confocal immunofluorescence microscopy shows 2.5-fold more P-glycoprotein in the cytoplasm of MDR10V cells as compared to Dox40 cells. The cytoplasmic location of P- glycoprotein in the MDR10V cells is associated with a redistribution of doxorubicin. In Dox40 cells, doxorubicin is concentrated in the nucleus, whereas in MDR10V cells, 90% of doxorubicin is found in the cytoplasm. In the presence of equivalent intracellular doxorubicin, there was a decrease in DNA-protein crosslinks in the MDR10V cell line compared to the Dox40 cell line. This finding is in agreement with the intracellular doxorubicin fluorescence studies showing less doxorubicin in the nuclei of MDR10V cells compared to Dox40 cells. Verapamil is less effective in increasing doxorubicin accumulation in the nuclei of MDR10V cells compared to Dox40 cells. Processing of P-glycoprotein from the endoplasmic reticulum to the medial Golgi was identical between the two cell lines as determined by endoglycosidase H sensitivity of newly sensitized P-glycoprotein. No mutations were found in MDR1 cDNA from MDR10V cells compared to Dox40 cells. These results suggest that resistance to chemosensitizing agents plus cytotoxic drugs is associated with a redistribution of P-glycoprotein from the plasma membrane to the cytoplasm, which in turn reduces the amount of cytotoxic drug reaching the nucleus.

Futscher, B., Vrba, L., Muñoz-Rodríguez, J. L., Stampfer, M. R., & Futscher, B. W. (2013). miRNA gene promoters are frequent targets of aberrant DNA methylation in human breast cancer. PloS one, 8(1).

miRNAs are important regulators of gene expression that are frequently deregulated in cancer, with aberrant DNA methylation being an epigenetic mechanism involved in this process. We previously identified miRNA promoter regions active in normal mammary cell types and here we analyzed which of these promoters are targets of aberrant DNA methylation in human breast cancer cell lines and breast tumor specimens. Using 5-methylcytosine immunoprecipitation coupled to miRNA tiling microarray hybridization, we performed comprehensive evaluation of DNA methylation of miRNA gene promoters in breast cancer. We found almost one third (55/167) of miRNA promoters were targets for aberrant methylation in breast cancer cell lines. Breast tumor specimens displayed DNA methylation of majority of these miRNA promoters, indicating that these changes in DNA methylation might be clinically relevant. Aberrantly methylated miRNA promoters were, similar to protein coding genes, enriched for promoters targeted by polycomb in normal cells. Detailed analysis of selected miRNA promoters revealed decreased expression of miRNA linked to increased promoter methylation for mir-31, mir-130a, let-7a-3/let-7b, mir-155, mir-137 and mir-34b/mir-34c genes. The proportion of miRNA promoters we found aberrantly methylated in breast cancer is several fold larger than that observed for protein coding genes, indicating an important role of DNA methylation in miRNA deregulation in cancer.

Grabowski, D. T., Pieper, R. O., Futscher, B. W., Deutsch, W. A., Erickson, L. C., & Kelley, M. R. (1992). Expression of ribosomal phosphoprotein PO is induced by antitumor agents and increased in Mer- human tumor cell lines. Carcinogenesis, 13(2), 259-263.

PMID: 1740017;Abstract:

We initiated this study to determine whether three structurally related bifunctional alkylating agents could induce the expression of a presumptive human DNA repair gene. The gene chosen for this study is known to encode the ribosomal phosphoprotein PO, but ironically may also share functions related to DNA repair. We now show by Northern analysis that PO is induced by L-phenylalanine mustard, 4-hydroperoxycyclophosphamide and mechlorethamine, which are DNA-damaging agents commonly used as chemotherapeutic antitumor agents. In further support of its involvement in DNA repair is the finding of a 30- to 50-fold constitutive overexpression of the PO gene in human tumor cell lines that are Mer-, cells which lack O6-methylguanine methyltransferase activity, when compared to Mer+ cell lines. This constitutively elevated level of PO in Mer- cell lines, which are thus DNA repair defective for O6-alkyguanine lesions, was not observed for other genes tested, including the human ribosomal gene S17 whose mRNA steady-state levels were uniformly the same in both Mer- and Mer+ cells. Taking these data together, it appears that increased levels of PO are somehow linked to DNA repair, and increased expression of PO may compensate for the decreased O6-methylguanine DNA methyltransferase activity in Mer- cells. Furthermore, the PO gene has also been shown to be overexpressed in colorectal tumors and polyps and the sera of some systemic lupus erythematosus patients contain antibodies against PO. The titer of the anti-PO antibodies rises significantly during lupus psychosis.

Novak, P., Jensen, T. J., Garbe, J. C., Stampfer, M. R., & Futscher, B. W. (2009). Stepwise DNA methylation changes are linked to escape from defined proliferation barriers and mammary epithelial cell immortalization. Cancer Research, 69(12), 5251-5258.

PMID: 19509227;PMCID: PMC2697259;Abstract:

The timing and progression of DNA methylation changes during carcinogenesis are not completely understood. To develop a timeline of aberrant DNA methylation events during malignant transformation, we analyzed genome-wide DNA methylation patterns in an isogenic human mammary epithelial cell (HMEC) culture model of transformation. To acquire immortality and malignancy, the cultured finite lifespan HMEC must overcome two distinct proliferation barriers. The first barrier, stasis, is mediated by the retinoblastoma protein and can be overcome by loss of p16INK4A expression. HMEC that escape stasis and continue to proliferate become genomically unstable before encountering a second more stringent proliferation barrier, telomere dysfunction due to telomere attrition. Rare cells that acquire telomerase expression may escape this barrier, become immortal, and develop further malignant properties. Our analysis of HMEC transitioning from finite lifespan to malignantly transformed showed that aberrant DNA methylation changes occur in a stepwise fashion early in the transformation process. The first aberrant DNA methylation step coincides with overcoming stasis, and results in few to hundreds of changes, depending on how stasis was overcome. A second step coincides with immortalization and results in hundreds of additional DNA methylation changes regardless of the immortalization pathway. A majority of these DNA methylation changes are also found in malignant breast cancer cells. These results show that large-scale epigenetic remodeling occurs in the earliest steps of mammary carcinogenesis, temporally links DNA methylation changes and overcoming cellular proliferation barriers, and provides a bank of potential epigenetic biomarkers that may prove useful in breast cancer risk assessment. ©2009 American Association for Cancer Research.

Teoh-Fitzgerald, M. L., Fitzgerald, M. P., Jensen, T. J., Futscher, B. W., & Domann, F. E. (2012). Genetic and epigenetic inactivation of extracellular superoxide dismutase promotes an invasive phenotype in human lung cancer by disrupting ECM homeostasis. Molecular Cancer Research, 10(1), 40-51.

PMID: 22064654;PMCID: PMC3262094;Abstract:

Extracellular superoxide dismutase (EcSOD) is an important superoxide scavenger in the lung in which its loss, sequence variation, or abnormal expression contributes to lung diseases; however, the role of EcSOD in lung cancer has yet to be studied. We hypothesized that EcSOD loss could affect malignant progression in lung, and could be either genetic or epigenetic in nature. To test this, we analyzed EcSOD expression, gene copy number, promoter methylation, and chromatin accessibility in normal lung and carcinoma cells.Wefound that normal airway epithelial cells expressed abundant EcSOD and had an unmethylated promoter, whereas EcSOD-negative lung cancer cells displayed aberrant promoter hypermethylation and decreased chromatin accessibility. 5-aza-dC induced EcSOD suggesting that cytosine methylation was causal, in part, to silencing. In 48/50 lung tumors, EcSOD mRNA was significantly lower as early as stage I, and the EcSODpromoter was hypermethylated in 8/10 (80%) adenocarcinomas compared with 0/5 normal lung samples. In addition, 20% of the tumors showed loss of heterozygosity (LOH) of EcSOD. Reexpression of EcSOD attenuated the malignant phenotype of lung carcinoma cells by significantly decreasing invasion and survival. Finally, EcSOD decreased heparanase and syndecan-1 mRNAs in part by reducing NF-κB. By contrast, MnSOD and CuZnSOD showed no significant changes in lung tumors and had no effect on heparanase expression. Taken together, the loss of EcSOD expression is unique among the superoxide dismutases in lung cancer and is the result of EcSOD promoter methylation and LOH, suggesting that its early loss may contribute to ECM remodeling and malignant progression. ©2011 AACR.