Extrathymic T cells expand in nude mice following different allogeneic stimuli

Tumor-suppressive effect of Reg3A in COAD is mediated by T cell activation in nude mice

Regenerating family protein 3 A (Reg3A) is highly expressed in a variety of organs and inflammatory tissues, and is closely related to tumorigenesis and cancer progression. However, clinical statistics show that high expression of Reg3A is associated with better prognosis in colorectal cancer (CRC) patients, suggesting a tumor-suppressive effect. The precise action and underlying mechanism of Reg3A in CRC remain controversial. The present study sought to investigate the relationship among Reg3A expression, CRC development, and immune cell alteration in patients using the TCGA, GEPIA, PrognoScan, TIMER and TISIDB databases. Reg3A-overexpressing LoVo cell line (LoVo-Reg3A), a representative of colon adenocarcinoma (COAD), was constructed and the action of Reg3A was assessed in a xenograft nude mouse model. Our bioinformatical analyses revealed that Reg3A upregulation is highly associated with CRC, along with increased frequency of immune cell infiltration. In the xenograft nude mice, Reg3A overexpression offered a tumor-suppressive effect by inhibiting cell proliferation and promoting apoptosis. The result of RNA-seq suggested a positive regulation of leukocytes and an upregulation of T cells in LoVo-Reg3A tumor tissue. CD4+ and CD8+ T cells in tumors, splenic Reg3A-reactive IFN-γ+/CD4+ T cells, and serum TNF-α, IFN-γ and IL-17 were significantly increased by Reg3A overexpression. In the ex vivo co-culture experiment, elevated cytotoxic effect, increased proportion of CD3ε+ T cells, and upregulated expressions of TNF-α, IFN-γ and IL-17 were detected in the PBMCs isolated from LoVo-Reg3A cell-xenografted nude mice. In conclusion, high expression of Reg3A could activate and recruit T cells in COAD leading to the cytotoxic tumor-suppressive effect.

The cyclic GMP/protein kinase G pathway as a therapeutic target in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive disease with high mortality. Treatments, which can result in significant morbidity, have not substantially changed in three decades. The second messenger cyclic GMP (cGMP), which targets protein kinase G (PKG), is generated by guanylate cyclases (GCs), and is rapidly hydrolyzed by phosphodiesterases (PDEs). Activation of the cGMP/PKG pathway is antineoplastic in several cancer types, but its impact on HNSCC has not been fully exploited. We found differential expression of critical components of this pathway in four HNSCC cell lines. Several activators of soluble GC (sGC), as well as inhibitors of PDE5, increased intracellular cGMP, reduced cell viability, and induced apoptosis in HNSCC cells. The apoptotic effects of the sGC activator BAY 41-2272 and the PDE5 inhibitor Tadalafil (Cialis) were mediated by PKG. Furthermore, Tadalafil substantially reduced the growth of CAL27-derived tumors in athymic mice. Several drugs which either activate sGC or inhibit PDE5 are approved for treatment of nonmalignant conditions. These drugs could be repurposed as novel and effective therapeutics in patients with head and neck cancer.

BAT mAb induces lymphopoiesis in nude mice

The athymic nude mouse provides a powerful tool in the study of human tumors, as it enables growth of human tumors due to deficiencies in T cell functions. However, deficiencies in T cell functions might limit research on efficacy of immune modulators in cancer immunotherapy. BAT mAb mediates its anti-cancer activity through modulation of the immune system that involves both NK and T cells. We analyzed lymphocyte populations in blood 5 and 14 days following the injection of BAT antibody alone or following engraftment of human colon carcinoma cells. Our results demonstrate that BAT injection induced lymphopoiesis in the nude mouse. Percentage of CD3 cells increased up to 24%, CD4 cells up to 20% but no increase was found in CD8 T cells in BAT-injected nude mice. Injection of BAT 12 days post-tumor engraftment propagated CD3, CD4 and CD8 cells seen in the blood 5 days later but not seen in the blood 14 days post-BAT injection. It is possible that this decrease is associated with migration of the lymphocytes from the blood to the tumor sites in the livers. The percentage of CD56-positive NK cells increased (up to 18%) by BAT administration alone or post-tumor injection. The presence of tumors alone did not induce lymphopoiesis in the nude mice. Propagation and lymphopoiesis by BAT mAb might have future clinical implications.