[Show abstract][Hide abstract] ABSTRACT: Many cancer treatments induce cell death through lethal oxidative stress. Oxidative stress also induces the activation of the calcium/calmodulin-dependent kinases (CaM-Ks), CaM-KII and CaM-KIV. In turn, the CaM-Ks are known to induce the activation of antiapoptotic signaling pathways, such as Akt, ERK, and NF-kappaB in many different cell types. The aim of this study was to determine the role of CaM-Kinases in resistance to hydrogen peroxide and three oxidative stress-inducing cancer therapies in MCF-7 breast cancer cells. We found that oxidative stress induced CaM-Kinase activity in MCF-7 breast cancer cells and that CaM-K inhibition increased hydrogen peroxide-induced cell death in MCF-7 human breast cancer cells. When MCF-7 cells were treated with doxorubicin, ionizing radiation, or photodynamic therapy in the presence of a CaM-K inhibitor a greater level of cell killing was observed than when cells were treated with doxorubicin, ionizing radiation, or photodynamic therapy alone. In support of this finding, CaM-K inhibition increased hydrogen peroxide-induced apoptosis in MCF-7 cells, as determined by increased number of apoptotic cells, DNA fragmentation, and PARP cleavage. Pharmacological and molecular inhibition indicated that CaM-KII was participating in hydrogen peroxide-induced ERK phosphorylation in breast cancer cells indicating a potential mechanism by which this sensitization occurs. This is the first time that CaM-K inhibition is reported to sensitize cancer cells to reactive oxygen intermediate inducing cancer treatments.
Cancer biology & therapy 09/2006; 5(8):1022-30. · 3.29 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In order to diagnose colon cancer at an earlier, more localized stage, there is a need to develop diagnostic markers (genes) which can detect early patterns of gene expression in exfoliated colonocytes shed in the stool during routine screening for this disease. An RNA-based detection is more pertinent than either a DNA-based or a protein-based method as a screening procedure, but it has not been widely used as a cancer screen because of the difficulty of handling and stabilizing the RNA molecule. We describe a method that permits extraction of intact nondegraded total RNA from human colonocytes in stool and from normal and malignant colon tissues (which were employed for comparison with stool). Because it utilizes commercially available kits, this method is simpler than other published methods and does not require isolation of messenger (m)RNA, thereby reducing the chances of contaminating the preparations with degrading nucleases, and even a small amount of isolated total RNA can be adequately reverse transcribed, making high-quality copy (c) DNA. This is followed by PCR (either qualitative end point or semiquantitative real-time) using colon cancer-specific gene primers. By routinely and systematically being able to perform quantitative gene expression measurements on noninvasive samples, the goal of this pilot work is to lay the groundwork for conducting a large clinical study to identify groups of selected genes whose expression is consistently altered at an early stage in the neoplastic process. Such work will permit noninvasive monitoring of at-risk patients through the analysis of their stool samples. Correct diagnosis will allow for surgical and/or other interventions before the tumor is well established and, thus, should decrease mortality from this preventable disease.
Digestive Diseases and Sciences 01/2004; 49(11-12):1889-98. · 2.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The response of the blood-forming and supportive stromal compartments of the marrow to a localized, fractionated course of radiotherapy [FxRT; 2.0 Gy (q24 h x 5)-->74 Gy] was examined in the C57Bl/6 mouse using the hematopoietic progenitor and the cobblestone-forming cell (CAFC) assays as end-points for the blood-forming compartment and the long-term bone marrow culture (LTBMC) to assess stromal integrity. Both during and subsequent to FxRT, hematopoietic activity in the irradiated femur was significantly dampened, although an abortive attempt at recovery was observed subsequent to the completion of FxRT. Moreover, both the CAFC subpopulations as well as the functional integrity of LTBMC generated from the irradiated femur were significantly compromised by FxRT. Of interest, restoration of the more primitive CAFC subpopulations to near normal levels was observed in the absence of a comparable recovery of the more mature CAFC subpopulations and the restoration of stromal integrity to the irradiated marrow. As a result, the data are consistent with the generation of a persisting FxRT-induced lesion in the microenvironmental stroma that effectively interferes with the normal regulation of hematopoietic differentiation and the recovery of hematopoietic activity in the irradiated marrow.
Anticancer research 01/2003; 23(3B):2625-31. · 1.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Interleukin-1alpha (IL-1) is known to radioprotect the gastrointestinal tract, but the mechanism by which this protection occurs remains unclear. These studies were undertaken to investigate whether the radioprotective potential of IL-1 may be linked to an ability to reduce apoptosis within the gastrointestinal crypts.
IL-1 was administered to C57Bl/6 mice 24 hours prior to receiving 8 Gy abdominal X-irradiation (xRT). At designated times, experimental mice were sacrificed, jejunal tissue removed, and paraffin-embedded sections analyzed for apoptosis indices (AI) and immunohistochemical determination of active caspase-3, -8 and -9.
AI data demonstrated that 8 Gy irradiation resulted in a marked jejunal apoptotic response, but IL-1 pretreatment significantly attenuated this response. Concomitant with this attenuation, reduced levels of caspase-3 and 9, but not caspase-8, activation were observed, particularly within goblet cells.
The results outlined herein suggest that radioprotection by IL-1 is mediated, at least in part, through a reduction in the apoptotic response which appears to involve down-regulation of the intrinsic apoptotic pathway.
Anticancer research 28(6A):3601-7. · 1.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study sought to better define the immunological impact of combining neoadjuvant total androgen suppression (TAS) with radiotherapy (xRT) in treating prostate cancer.
Subjects selected (n = 37) were stage I-II prostate cancer patients meeting the eligibility requirements for RTOG protocols 94-08 or 94-13. Flow cytometric monitoring of circulating T helper (Th), T suppressor/cytotoxic (Ts), natural killer (NK) and B lymphocytes was performed weekly.
Significant reduction of all lymphocyte subsets occurred as a result of xRT. Comparison between treatment groups demonstrated that the B lymphocyte and NK lymphocyte radioresponse was not influenced by TAS, but the Th and Ts lymphocyte response was, with addition of TAS leading to less radiation-induced decline.
The basis for this T cell response is unclear, but may involve a TAS-induced reduction of testosterone's immunomodulation of T cell proliferation and apoptosis and/or a direct, TAS-induced thymic stimulation. Our data suggest that addition of TAS to xRT appears to have no detrimental effects on lymphocyte subsets, and, indeed, may have favorable effects on T cells.
Anticancer research 25(4):3159-66. · 1.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to investigate the immunological impact of combining neoadjuvant total androgen suppression (TAS) with radiotherapy (xRT) in the treatment of prostate cancer by monitoring blood cytokine levels.
Participants were stage I-II prostate cancer patients receiving xRT alone (n=18) or TAS+xRT (n=19) under the procedures outlined in RTOG protocols #94-08 and #94-13. Peripheral blood samples were collected immediately prior to TAS (xRT+TAS group), immediately prior to xRT, 24 hours after initiation of xRT, and weekly during xRT. Samples were monitored for the immunoregulatory cytokines interleukin (IL)-1beta, IL-6 and transforming growth factor (TGF)beta using ELISA procedures.
Following initiation of xRT, both patient groups demonstrated an immediate elevation of the proinflammatory cytokines IL-1beta and IL-6 in their plasma. These cytokine levels appeared to peak after 1-2 weeks of xRT before returning toward pre xRT levels. In contrast, the profibrotic cytokine TGFbeta appeared to decrease immediately following initiation of xRT, but, subsequently, underwent two distinct waves of elevation, occurring at 1-2 weeks and 5-6 weeks into the xRT. Surprisingly, while the temporal pattern of plasma cytokine response was similar in both treatment groups, the magnitude of cytokine expression was noticeably different, appearing to be significantly affected by the addition of TAS. Indeed, administration of neoadjuvant TAS appeared to bring about a marked elevation of IL-1beta and IL-6 and a significant reduction in TGFbeta when compared to patients receiving xRT alone.
The precise mechanisms underlying this TAS-related increase of the proinflammatory cytokines IL-1beta and IL-6 and decrease of the profibrotic cytokine TGFbeta remain unclear. However, previous reports have documented that androgens tend to be immunosuppressive in nature. It is conceivable, therefore, that administration of TAS shifts the ratio of proinflammatory and profibrotic cytokines toward a more immunostimulatory state.
In vivo (Athens, Greece) 23(5):827-33. · 1.15 Impact Factor