Colonic adenocarcinomas rapidly induced by the combined treatment with 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and dextran sodium sulfate in male ICR mice possess beta-catenin gene mutations and increases immunoreactivity for beta-catenin, cyclooxygenase-2 and inducible nitric oxide synthase

Heterocyclic amines are known to be important environmental carcinogens in several organs including the colon. The aim of this study was to induce colonic epithelial malignancies within a short-term period and analyze the expression of cycooxygenase (COX)-2, inducible nitric oxide synthase (iNOS) and beta-catenin, and mutations of beta-catenin gene in induced tumors. Male Crj: CD-1 mice were given a single i.g. administration (200 mg/kg body wt) of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) followed by 2% dextran sodium sulfate (DSS) in the drinking water for a week. The expression of beta-catenin, COX-2 and iNOS was immunohistochemically assessed in colonic epithelial lesions and the beta-catenin gene mutations in colonic adenocarcinomas induced were analyzed by the single strand conformation polymorphism method, restriction enzyme fragment length polymorphism and direct sequencing. At week 16, a high incidence of colonic neoplasms with dysplastic lesions developed in mice that received PhIP and DSS, but only a few developed in those given MeIQx and DSS. Immunohistochemically, the adenocarcinomas induced were all positive for three proteins. All seven adenocarcinomas induced by PhIP and DSS have mutations. The findings suggest that DSS exerts powerful tumor-promoting effects on PhIP-initiated colon carcinogenesis in mice and this mouse model is useful for investigating environment-related colon carcinogenesis within a short-term period.     

Activation of naïve CD4 T cells by anti-CD3 reveals an important role for Fyn in Lck-mediated signaling

Although there was no impairment in IL-2 secretion and proliferation of Fyn-deficient naïve CD4 cells after stimulation with antigen and antigen-presenting cells, stimulation of these cells with anti-CD3 and anti-CD28 revealed profound defects. Crosslinking of purified wild-type naïve CD4 cells with anti-CD3 activated Lck and initiated the signaling cascade downstream of Lck, including phosphorylation of ZAP-70, LAT, and PLC-γ1; calcium flux; and dephosphorylation and nuclear translocation of the nuclear factor of activated T cells (NFAT)p. All of these signaling events were diminished severely in Fyn-deficient naïve cells activated by CD3 crosslinking. Coaggregation of CD3 and CD4 reconstituted this Lck-dependent signaling pathway in Fyn^-/- T cells. These results suggest that when signaling of naïve T cells is restricted to the T cell antigen receptor, Fyn plays an essential role by positive regulation of Lck activity.Signaling through the T cell antigen receptor (TCR) is initiated by the activity of the Src family tyrosine kinases, Fyn and Lck (1). It has been shown in numerous studies using Lck-deficient cell lines and mice whose peripheral T cells are deficient in Lck that this enzyme plays a critical upstream role in the signaling cascade leading to T cell development, activation, and differentiation (2). In contrast to Lck, the role of Fyn kinase in T cell activation and development is less well defined. With the exception of natural killer T (NKT) cells (3, 4), Fyn deficiency has little or no effect on T cell development in the thymus, and peripheral T cells from Fyn-deficient mice, to the extent they have been studied, show variable and incomplete defects in mounting immune responses (5-7). These findings are consistent with the concept that, for the most part, Fyn is a redundant Src kinase without a unique function in the signaling of T cells. The finding that some of the substrates for Lck [such as the immunoreceptor tyrosine-based activation motifs (ITAMs) of TCRζ as well as CD3γδε] can also serve as substrates for Fyn (8) supports this view. Furthermore, some substrates of ZAP-70, such as Vav (9) and SLP 76 (8), are also substrates of Fyn. However, other studies have shown that Fyn has its own unique substrates, some of which play significant roles in T cell activation. These include ADAP (SLAP-130/FYB) (10), Pyk2 (11), WASp (12), and CBP (13). Other indications that Fyn plays some unique role in TCR-mediated signaling come from our previous studies that have shown that stimulation of T cells with low affinity ligands that function as TCR antagonists leads to preferential activation of Fyn in the absence of any detectable changes in the activity of Lck or ZAP-70 (14, 15). Also, Fyn-deficient T cells are particularly inefficient at responding to weak TCR agonists (7).Because of these more recent findings that suggest a unique role for Fyn in T cell activation, we have reinvestigated the capacity of Fyn-deficient T cells to respond to TCR-mediated signaling in this study. We compared naïve CD4 T cells from Fyn-deficient and wild-type mice that contained a TCR transgene for their capacity to respond to either antigen presented by antigen-presenting cells (APCs) or to respond to antibody-mediated CD3 crosslinking. These experiments demonstrated that the relative importance of Fyn depended highly on the mode of stimulation and the activation status of T cells; stimulation of Fyn-deficient T cells by antigen-pulsed APCs led to a robust proliferative and IL-2 response, whereas anti-CD3-mediated stimulation revealed a profound signaling defect in Fyn-deficient T cells. This defect could be corrected by the cocrosslinking of CD3 with CD4. Furthermore, the signaling defect of Fyn-deficient T cells stimulated with anti-CD3 was restricted to naïve T cells and was not observed when Fyn-deficient effector T cells were analyzed. Biochemical experiments on anti-CD3 stimulated cells strongly suggest that the presence of Fyn was necessary for an effective recruitment and/or activation of Lck in the region of the TCR.     

Cyclooxygenase 2 genotypes influence prostate cancer susceptibility in Japanese Men

This study aims to evaluate the relationship between the cyclooxygenase 2 (COX2) G1195A (rs689465) polymorphism and the risk of prostate cancer in a Japanese population and the associations between COX2 polymorphisms and clinicopathological characteristics, including Gleason grade and prostate-specific antigen (PSA) grade. We recruited 134 patients with prostate cancer and 86 healthy controls matched for age and smoking status. The COX2 G1195A polymorphism status was determined by polymerase chain reaction and restriction fragment length polymorphism analysis. Genotype distributions (p?=?0.028) and allelic frequencies (p?=?0.014) differed significantly between prostate cancer and control groups in terms of the COX2 G1195A polymorphism (Pearson’s χ ² test). Logistic regression analysis of case and control outcomes showed an odds ratio between the GG and AA genotypes of 3.15 (95 % confidence interval?=?1.27–8.08, p?=?0.014), indicating an increased risk of prostate cancer associated with the AA genotype. Subset analysis revealed no significant associations between this polymorphism and clinicopathological characteristics of prostate cancer. This study demonstrated a relationship between the COX2 G1195A variant and prostate cancer risk. This polymorphism may merit further investigation as a potential genomic marker for the early detection of prostate cancer. Our results support the hypothesis that rs689465 influences susceptibility to prostate cancer; however, prostate cancer progression was not associated with rs689465 in a Japanese population.     

A case of metaplastic breast cancer that showed a good response to platinum-based preoperative chemotherapy

Patients with metaplastic breast cancer (MBC) exhibit reduced response to chemotherapy and have poor prognosis. We investigated a case of MBC that showed a positive response to preoperative chemotherapy, resulting in near pathological complete response (pCR). A 59-year-old woman complained of a lump in her right breast. Magnetic resonance imaging (MRI) showed the presence of a solid mass that was 24 mm in diameter. The pathological diagnosis was MBC with cartilaginous differentiation. The clinical stage was T2N0M0, stage IIA according to the International Union against Cancer (UICC) criteria. To observe the response to chemotherapy, we gave her preoperative chemotherapy. The patient was monitored closely, since we realized that failure of chemotherapy carries a risk of tumor progression. Evaluation was carried out using ultrasound, MRI, fluorodeoxyglucose (FDG) positron emission tomography (PET), and a Ki-67 labeling index after the first cycle of chemotherapy, and ultrasound after each additional cycle. FDG-PET showed a positive response after the first cycle of chemotherapy. The patient underwent 4 cycles of docetaxel (75 mg/m²) and cisplatin (75 mg/m²) followed by 4 cycles of cyclophosphamide (500 mg/m²), doxorubicin (50 mg/m²), and cisplatin (50 mg/m²). Ultrasound showed decreases in tumor size after each cycle of chemotherapy. After chemotherapy, MRI showed nearly complete regression of the tumor. Partial mastectomy was performed. Pathological examination showed few cancer cells remaining, indicating near pCR. We report a case of MBC that responded well to platinum-based preoperative chemotherapy. We propose that preoperative chemotherapy may be an option for treatment of MBC in conjunction with careful monitoring.     

TCR antagonist peptides induce formation of APC-T cell conjugates and activate a Rac signaling pathway

T cell receptor antagonists inhibit T cell activation by antigen, and by themselves fail to induce phenotypic changes associated with T cell activation. However, they can induce limited tyrosine phosphorylation of TCRzeta chain. Here we show that TCR antagonists are potent inducers of APC-T cell conjugates, cytoskeletal reorganization, and capping of certain T cell proteins. These events are associated with a signaling pathway involving tyrosine phosphorylation of Vav and SLP-76, activation and capping of Rac-1, a protein previously linked with cytoskeletal reorganization, and activation of JNK. The finding that antagonist peptides stimulate this pathway, while failing to stimulate other TCR-mediated signaling pathways, indicates the presence in T cells of a hierarchy of signaling that is sensitive to the avidity of Ag / MHC-TCR interaction.     

An analysis of characters and changes of the blood pressure in 29 cases on recurrence of cerebral infarction]

We investigated changes of the blood pressure in 29 stroke patients before stroke recurrence and after recurrence. Additional antihypertensive drugs were not administered to all patients after stroke recurrence. Twenty-five lacunar infarct patients and 4 atherothrombotic infarct patients were included in this study. A significant difference was observed between the systolic blood pressure(SBP) within 4 weeks before recurrence and that just after recurrence(132.8 +/- 17.2 mmHg vs. 157.4 +/- 21.3 mmHg, Wilcoxon rank sum test, p < 0.001), or between the SBP just after and 2 weeks after stroke recurrence(157.4 +/- 21.3 mmHg vs. 138.0 +/- 18.3 mmHg, Wilcoxon rank sum test, p < 0.001). The similar difference was found in the diastolic blood pressure(DBP) or in the mean arterial blood pressure(MABP). There was no significant difference in the SBP, the DBP or the MABP between the patients before and 2 weeks after the stroke recurrence. These results suggested that the elevation of the blood pressure at recurrence decreased spontaneously to the pre-recurrence level of the blood pressure in about 2 weeks.     

Advances in personalized cancer immunotherapy

There are currently three major approaches to T cell-based cancer immunotherapy, namely, active vaccination, adoptive cell transfer therapy and immune checkpoint blockade. Recently, this latter approach has demonstrated remarkable clinical benefits, putting cancer immunotherapy under the spotlight. Better understanding of the dynamics of anti-tumor immune responses (the “Cancer-Immunity Cycle”) is crucial for the further development of this form of treatment. Tumors employ multiple strategies to escape from anti-tumor immunity, some of which result from the selection of cancer cells with immunosuppressive activity by the process of cancer immunoediting. Apart from this selective process, anti-tumor immune responses can also be inhibited in multiple different ways which vary from patient to patient. This implies that cancer immunotherapy must be personalized to (1) identify the rate-limiting steps in any given patient, (2) identify and combine strategies to overcome these hurdles, and (3) proceed with the next round of the “Cancer-Immunity Cycle”. Cancer cells have genetic alterations which can provide the immune system with targets by which to recognize and eradicate the tumor. Mutated proteins expressed exclusively in cancer cells and recognizable by the immune system are known as neoantigens. The development of next-generation sequencing technology has made it possible to determine the genetic landscape of human cancer and facilitated the utilization of genomic information to identify such candidate neoantigens in individual cancers. Future immunotherapies will need to be personalized in terms of the identification of both patient-specific immunosuppressive mechanisms and target neoantigens.