Behavioral and transcriptomic effects of the cancer treatment tamoxifen in mice.

Introduction: Tamoxifen is a common treatment for estrogen receptor-positive breast cancer. While tamoxifen treatment is generally accepted as safe, there are concerns about adverse effects on cognition. Methods: We used a mouse model of chronic tamoxifen exposure to examine the effects of tamoxifen on the brain. Female C57/BL6 mice were exposed to tamoxifen or vehicle control for six weeks; brains of 15 mice were analyzed for tamoxifen levels and transcriptomic changes, and an additional 32 mice were analyzed through a battery of behavioral tests. Results: Tamoxifen and its metabolite 4-OH-tamoxifen were found at higher levels in the brain than in the plasma, demonstrating the facile entry of tamoxifen into the CNS. Behaviorally, tamoxifen-exposed mice showed no impairment in assays related to general health, exploration, motor function, sensorimotor gating, and spatial learning. Tamoxifen-treated mice showed a significantly increased freezing response in a fear conditioning paradigm, but no effects on anxiety measures in the absence of stressors. RNA sequencing analysis of whole hippocampi showed tamoxifen-induced reductions in gene pathways related to microtubule function, synapse regulation, and neurogenesis. Discussion: These findings of the effects of tamoxifen exposure on fear conditioning and on gene expression related to neuronal connectivity suggest that there may be CNS side effects of this common breast cancer treatment.

Chemotherapy promotes astrocytic response to Aß deposition, but not Aß levels, in a mouse model of amyloid and APOE.

Many cancer survivors experience cancer-related cognitive impairment (CRCI), which is characterized by problems of attention, working memory, and executive function following chemotherapy and/or hormonal treatment. APOE4, the strongest genetic risk factor for Alzheimer's Disease (AD), is also a risk factor for CRCI, especially among survivors exposed to chemotherapy. We explored whether the effects of APOE genotype to chemotherapy were associated with an increase in AD pathological processes, using a mouse model of amyloid (5XFAD) along with the E3 or E4 alleles of human APOE (E3FAD and E4FAD). Six-month-old female E3FAD mice (control n = 5, treated n = 5) and E4FAD (control n = 6, treated n = 6) were treated with two doses of doxorubicin (total 10 mg/kg) or DMSO vehicle. After six weeks, mice were euthanized and brains were analyzed by immunohistochemistry and biochemical assays. Doxorubicin-treated mice had the same level of Aß in the brain as control mice, as measured by 6E10 immunohistochemistry, Aß40 and Aß42 ELISAs, and plaque morphologies. Doxorubicin significantly increased the level of the astrocytic response to Aß deposits, which was independent of APOE genotype; no effects of doxorubicin were observed on the microglial responses. These data are consistent with a model in which the effects of doxorubicin on risk of CRCI are unrelated amyloid accumulation, but possibly related to glial responses to damage.

Survivin, sonic hedgehog, krüppel-like factors, and p53 pathway in serous ovarian cancer: an immunohistochemical study.

Survivin was previously associated with tumor stage and grade in ovarian cancer and interfered with the tumor's drug sensitivity. In addition, Survivin expression was found to be regulated by the Sonic hedgehog (Shh) pathway, Krüppel-like factor (KLF) family proteins, and p53 pathway. The main aim of this study was to assess the prognostic values of immunohistochemical expression of Survivin, Klf5, Klf11, Shh, p53, p21, and Mdm2 in a cohort of high-grade ovarian serous cancers. Other aims were comparison between high- and low-grade ovarian serous cancer and between platinum-resistant and the other cases. The last aim was to assess the correlations among the immunohistochemical expression of the studied proteins. Retrospective cohort study to assess immunohistochemical expression of Survivin, Klf5, Klf11, Shh, p53, p21, and Mdm2 in a tissue microarray of primary tumor samples among 73 women affected by high-grade ovarian serous cancer and 9 by low-grade ovarian serous cancer. Klf5 and Shh cytoplasmic staining were associated with short overall survival (HR 6.38, 95% CI 2.25-18.01, P < .05 and 2.25, 95% CI 1.19-4.23, P < .05, respectively). In addition, cytoplasmic Klf5 staining, high Klf11, and p53 nuclear staining were associated with platinum resistance (P < .05). Cytoplasmic Shh score was significantly correlated to the immunohistochemical expression of Klf5, Klf11, Mdm2, and Survivin. Our data highlight the possible role of Klf5 and Shh as prognostic markers, meanwhile confirming the role of the KLF family proteins and p53 in ovarian cancer drug resistance. Moreover, Shh appeared to play an important role in the intracellular network of ovarian neoplasia.