Manganese superoxide dismutase deficiency enhances cell turnover via tumor promoter-induced alterations in AP-1 and p53-mediated pathways in a skin cancer model

Previous studies in our laboratories demonstrated that overexpression of manganese superoxide dismutase (MnSOD) suppressed both the incidence and multiplicity of papillomas in a DMBA/TPA multi-stage skin carcinogenesis model. The activity of activator protein-1 (AP-1), which is associated with tumor promotion, was reduced in MnSOD transgenic mice overexpressing MnSOD in the skin, suggesting that MnSOD may reduce tumor incidence by suppressing AP-1 activation. In the present study, we report that reduction of MnSOD by heterozygous knockout of the MnSOD gene (Sod2 -/+, MnSOD KO) increased the levels of oxidative damage proteins and the activity of AP-1 following TPA treatment. RNA levels of ornithine decarboxylase (ODC) were also increased, suggesting an increase in cell proliferation in the KO mice. Histological examination confirmed that the number of proliferating cells in DMBA/TPA-treated mouse skin were higher in the KO mice. Interestingly, histological examination also demonstrated greater numbers of apoptotic cells in the KO mice after DMBA/TPA treatment. Evidence of apoptosis, including DNA fragmentation, cytochrome c release from mitochondria, and caspase 3 activation were also observed by biochemical assays of the skin tissues. Apoptosis was associated with an increase in nuclear levels of p53 as determined by Western analysis. Quantitative immunogold ultrastructural analysis confirmed that p53 immunoreactive protein levels were increased to a greater level in the nuclei of epidermal cells from MnSOD KO mice compared to epidermal nuclei from wild type mice similarly treated. Moreover, p53 levels further increased in the mitochondria of DMBA/TPA treated mice, and this increase was much greater in the MnSOD KO than in the wild type mice, suggesting a link between MnSOD deficiency and mitochondrial-mediated apoptosis. Pathological examination reveals no difference in the incidence and frequency of papillomas comparing the KO mice and their wild type littermates. Taken together, these results suggest that: (1) MnSOD deficiency enhanced TPA-induced oxidative stress and AP-1 and p53 levels, consistent with the increase in both proliferation and apoptosis events in the MnSOD KO mice, and (2) increased apoptosis may negate increased proliferation in the MnSOD deficient mice during an early stage of tumor development.     

Manganese superoxide dismutase overexpression inhibits the growth of androgen-independent prostate cancer cells

This study investigates the role of the antioxidant enzyme manganese superoxide dismutase (MnSOD) in androgen-independent human prostate cancer (PC-3) cells' growth rate in vitro and in vivo. MnSOD levels were found to be lower in parental PC-3 cells compared to nonmalignant, immortalized human prostate epithelial cells (P69SV40T). To unravel the role of MnSOD in the prostate cancer phenotype, PC-3 cells were stably transfected with MnSOD cDNA plasmid. The MnSOD protein and activity levels in clones overexpressing MnSOD were increased seven- to eightfold. These cell lines showed elongated cell doubling time, reduced anchorage-independent growth in soft agar compared to parental PC-3 (Wt) cells, and reduced growth rate of PC-3 tumor xenografts in athymic nude mice. Flow cytometric studies showed an increase in membrane potential in the MnSOD-overexpressing clone (Mn32) compared to Wt and Neo cells. Also, production of extracellular H(2)O(2) was increased in the MnSOD-overexpressing clones. As determined by DNA cell cycle analysis, the proportion of cells in G(1) phase was enhanced by MnSOD overexpression. Therefore, MnSOD not only regulates cell survival but also affects PC-3 cell proliferation by retarding G(1) to S transition. Our results are consistent with MnSOD being a tumor suppressor gene in human prostate cancer.     

Civil defence in a nuclear disaster

Any nuclear war would be horrific and our main aim should be universal abolition of nuclear weapons. Civil defence, with its medical attributes, could certainly increase the survival rate should a disaster occur. The effect of the explosion of a nuclear warhead is outlined, together with what could be done to reduce casualties. Nuclear winter is discussed and it is suggested that the results of computerization of doubtful surmises have been treated too much as proven facts. The possibility of its occurrence should not deter emergency planning. Civil defence can save lives, and the fact that medicine as we know it would cease to exist in an all‐out nuclear war does not excuse us from doing what we can to increase the survival rate, if the worst should happen. Action should therefore be taken now to plan decentralization of resources and to instruct the public in protection, first aid and self‐sufficiency.     

Association of clinical trial enrollment and survival using contemporary therapy for pediatric acute lymphoblastic leukemia

While early studies reported superior survival for cancer patients enrolled on clinical trials, recent findings are inconclusive. We investigated the association between enrollment on contemporary trials and event‐free survival (EFS) in pediatric B‐cell acute lymphoblastic leukemia (B‐ALL). In a retrospective cohort of 274 children (1–21 years) treated for B‐ALL from 2008 to 2015, 55.5% enrolled with no disparity in enrollment by age, sex, or ethnicity. Three‐year EFS was similar for enrolled and not enrolled patients (90.1% [95% CI, 82.5–94.5] versus 86.5% [95% CI, 77.7–92.0]). Clinical trial enrollment did not affect pediatric B‐ALL survival, albeit in a limited‐size cohort treated at a single academic institution.     

Myeloid lineage switch following chimeric antigen receptor T‐cell therapy in a patient with TCF3‐ZNF384 fusion‐positive B‐lymphoblastic leukemia

A pediatric patient diagnosed initially with B‐lymphoblastic leukemia (B‐ALL) relapsed with lineage switch to acute myeloid leukemia (AML) after chimeric antigen receptor T‐cell (CAR‐T) therapy and hematopoietic stem cell transplant. A TCF3‐ZNF384 fusion was identified at diagnosis, persisted through B‐ALL relapse, and was also present in the AML relapse cell population. ZNF384‐rearrangements define a molecular subtype of B‐ALL characterized by a pro‐B‐cell immunophenotype; furthermore, ZNF384‐rearrangements are prevalent in mixed‐phenotype acute leukemias. Lineage switch following CAR‐T therapy has been described in patients with KMT2A (mixed lineage leukemia) rearrangements, but not previously in any patient with ZNF384 fusion.