Akira Hara

Nerve Growth Factor Promotes Gastric Tumorigenesis through Aberrant Cholinergic Signaling

Within the gastrointestinal stem cell niche, nerves help to regulate both normal and neoplastic stem cell dynamics. Here, we reveal the mechanisms underlying the cancer-nerve partnership. We find that Dclk1+ tuft cells and nerves are the main sources of acetylcholine (ACh) within the gastric mucosa. Cholinergic stimulation of the gastric epithelium induced nerve growth factor (NGF) expression, and in turn NGF overexpression within gastric epithelium expanded enteric nerves and promoted carcinogenesis. Ablation of Dclk1+ cells or blockade of NGF/Trk signaling inhibited epithelial proliferation and tumorigenesis in an ACh muscarinic receptor-3 (M3R)-dependent manner, in part through suppression of yes-associated protein (YAP) function. This feedforward ACh-NGF axis activates the gastric cancer niche and offers a compelling target for tumor treatment and prevention.

M2-like macrophage polarization in high lactic acid-producing head and neck cancer.

Reprogramming of glucose metabolism in tumor cells is referred to as the Warburg effect and results in increased lactic acid secretion into the tumor microenvironment. We have previously shown that lactic acid has important roles as a pro‐inflammatory and immunosuppressive mediator and promotes tumor progression. In this study, we examined the relationship between the lactic acid concentration and expression of LDHA and GLUT1, which are related to the Warburg effect, in human head and neck squamous cell carcinoma (HNSCC). Tumors expressing lower levels of LDHA and GLUT1 had a higher concentration of lactic acid than those with higher LDHA and GLUT1 expression. Lactic acid also suppressed the expression of LDHA and GLUT1 in vitro. We previously reported that lactic acid enhances expression of an M2 macrophage marker, ARG1, in murine macrophages. Therefore, we investigated the relationship between the lactic acid concentration and polarization of M2 macrophages in HNSCC by measuring the expression of M2 macrophage markers, CSF1R and CD163, normalized using a pan‐macrophage marker, CD68. Tumors with lower levels of CD68 showed a higher concentration of lactic acid, whereas those with higher levels of CSF1R showed a significantly higher concentration of lactic acid. A similar tendency was observed for CD163. These results suggest that tumor‐secreted lactic acid is linked to the reduction of macrophages in tumors and promotes induction of M2‐like macrophage polarization in human HNSCC.

p53 Expression as a Diagnostic Biomarker in Ulcerative Colitis-Associated Cancer

Ulcerative colitis (UC) is defined as an idiopathic inflammatory disorder primarily involving the mucosa and submucosa of the colon. UC-associated colon cancers (also known as colitic cancers) develop through the inflammation–dysplasia sequence, which is a major problem affecting the prognosis of patients with UC. It is therefore very important to detect malignancy from UC at an early stage. As precancerous lesions arising in UC, there are pathological adenomatous changes, basal cell changes, in situ anaplasia, clear cell changes, and pan-cellular change. It is considered that the mutation of the p53 gene plays a crucial role, and the protein expression of p53 in dysplastic crypts may serve as a good biomarker in the early stages of UC-associated colon carcinogenesis. Immunohistochemistry for p53 is a very valuable diagnostic tool in UC-associated colon cancers. However, protein expression of p53 is not always universal, and additional methods may be required to assess p53 status in UC-associated colon cancers.

Current mouse models of oral squamous cell carcinoma: Genetic and chemically induced models

Oral squamous cell carcinoma (OSCC) patients have a low 5-year survival rate and poor prognosis. To improve survival and prognosis, the causes and processes involved in lesion development should be evaluated. For this purpose, the use of OSCC mouse models, such as chemically induced mouse models, genetically modified mouse models, and transplanted (xenograft) models, is crucial. These OSCC models exhibit both advantages and disadvantages when studying OSCC development and progression. Until a model resembling human OSCC is developed, both the advantages and disadvantages of each model should be carefully considered. In this review, we discuss OSCC mouse models and their use in cancer research worldwide.

Expression analyses of Phactr1 (phosphatase and actin regulator 1) during mouse brain development

Phactr1 (Phosphatase and actin regulator 1) is abundantly expressed in the central nervous system and considered to regulate various neuronal processes through the regulation of protein phosphorylation and actin cytoskeletal organization. In this study, we prepared a specific antibody against Phactr1, anti-Phactr1, and carried out biochemical and morphological analyses of Phactr1 with mouse brain tissues. Western blotting analyses revealed that Phactr1 was expressed in a tissue-dependent profile in the young adult mouse and in a developmental stage-dependent manner in the mouse brain. In primary cultured hippocampal neurons, while Phactr1 was diffusely distributed in the nucleus and cytoplasm, it was visualized in axon and dendrites with partial colocalization with synapses. Phactr1 was also detected in the synaptosomal and postsynaptic density fractions in biochemical fractionation. Immunohistochemical analyses clarified that Phactr1 was differentially expressed in cortical neurons during corticogenesis; the protein was frequently accumulated in the nucleus at the embryonic stage while it came to diffusely distribute in the cell body at the prepubertal stage. The obtained results suggest that Phactr1 takes part in neuronal functions regulated in a spatiotemporal manner.

Current trends in mouse models of glioblastoma

Glioblastoma is the most deadly brain tumor type and is characterized by a severe and high rate of angiogenesis, remaining an incurable disease in the majority of cases. Mechanistic understanding of glioblastoma initiation and progression is complicated by the complexity of genetic and/or environmental initiating events and lack of clarity regarding the cell or tissue of origin. To determine these mechanisms, mouse models that recapitulate the molecular and histological characteristics of glioblastoma are required. Unlike in other malignancies, viral-mediated mouse models of glioblastoma rather than chemically induced mouse models have been developed because of its sensitivity to viruses. Based on recent molecular analyses reported for human glioblastoma, this review critically evaluates genetically engineered, xenograft, allograft, viral-mediated, and chemically induced mouse models of glioblastoma. Further, we focus on the clinical value of these models by examining their contributions to studies of glioblastoma prevention, tumorigenesis, and chemoresistance.

Imaging Characteristics of Malignant Sinonasal Tumors

Malignancies of the nasal cavity and paranasal sinuses account for 1% of all malignancies and 3% of malignancies of the upper aerodigestive tract. In the sinonasal tract, nearly half of all malignancies arise in the nasal cavity, whereas most of the remaining malignancies arise in the maxillary or ethmoid sinus. Squamous cell carcinoma is the most common histological subtype of malignant tumors occurring in this area, followed by other epithelial carcinomas, lymphomas, and malignant soft tissue tumors. Although many of these tumors present with nonspecific symptoms, each tumor exhibits characteristic imaging features. Although complex anatomy and various normal variants of the sinonasal tract cause difficulty in identifying the origin and extension of large sinonasal tumors, the invasion of vital structures such as the brain, optic nerves, and internal carotid artery affects patients’ prognosis. Thus, diagnostic imaging plays a key role in predicting the histological subtype and in evaluating a tumor extension into adjacent structures. This article describes the computed tomography and magnetic resonance imaging findings for malignant sinonasal tumors.

Neuropathological findings from an autopsied case showing posterior reversible encephalopathy syndrome-like neuroradiological findings associated with premedication including tacrolimus for autologous peripheral blood stem cell transplantation

Posterior reversible encephalopathy syndrome (PRES) is diagnosed based on neuroradiological findings. Typically, PRES is reversible and presents with a good outcome; however, fatal outcomes have been reported. We report an autopsied case showing PRES-like neuroradiological findings associated with premedication including tacrolimus for autologous peripheral blood stem cell transplantation in a 28-year-old woman with a 2-year history of acute myeloid sarcoma/acute myeloid leukemia. Neurological examination revealed disturbed consciousness, muscle weakness in all extremities, and bilaterally diminished tendon reflexes. Brain fluid attenuated inversion recovery MRI showed multiple bilateral hyper-intensity areas in the posterior white matter and left corona radiate. She died of respiratory arrest within 24h after PRES diagnosis. Neuropathological examination revealed diffuse cerebral edema, multiple cerebral hematomas that extended into the lateral ventricles and subarachnoid cavities, and multiple microbleeds predominantly in the inferior surface of the occipital white matter. Microscopic findings revealed paler myelin sheaths, enlargement of the vascular endothelium, leakage of plasma components and red blood cells, and clasmatodendrosis within the occipital white matter. Cerebral herniation and diffuse cerebral edema due to vascular endothelial dysfunction were concluded to be the cause of death. These pathological findings may aid in the pathophysiological recognition of acute-stage PRES.

Induction of humoral and cellular immune response to hepatitis B virus (HBV) vaccine can be upregulated by CpG oligonucleotides complexed with Dectin-1 ligand

A persistent hepatitis B virus (HBV) infection is characterized by a lack of or a weak immune response to HBV, which may be reflective of tolerance to HBV. Efficient induction of HBV‐specific immune response leads to the clearance of HBV in patients with a chronic HBV infection. CpG oligodeoxynucleotides (ODN) has a powerful adjuvant effect in HBV vaccination. A recent report demonstrated that the immunization by B/K CpG ODN (K3) wrapped by the nonagonistic Dectin‐1 ligand, schizophyllan (SPG), namely K3‐SPG, was more effective in the induction of antigen‐specific immune response than that by K3. In this study, we examined the efficacy of K3‐SPG as a HBV vaccine adjuvant. Wild‐type (WT) mice and HBV transgenic (HBV‐Tg) mice were subcutaneously immunized with hepatitis B surface antigen (HBsAg) alone, HBsAg and K3, or HBsAg and K3‐SPG. The vaccination with HBsAg and K3‐SPG significantly enhanced humoral and cellular immune response to HBV antigen compared to the other vaccinations in WT and HBV‐Tg mice. K3‐SPG induced the accumulation of dendritic cells (DCs) into draining lymph node and the activation of DCs. The expression of cytokines and chemokines related to Th1 and Th2 responses was upregulated after the vaccination including with K3‐SPG. In conclusion, these results indicated that the vaccination using K3‐SPG may overcome tolerance even in patients with chronic HBV infection.

Multifaceted Interpretation of Colon Cancer Stem Cells

Colon cancer is one of the leading causes of cancer-related deaths worldwide, despite recent advances in clinical oncology. Accumulating evidence sheds light on the existence of cancer stem cells and their role in conferring therapeutic resistance. Cancer stem cells are a minor fraction of cancer cells, which enable tumor heterogeneity and initiate tumor formation. In addition, these cells are resistant to various cytotoxic factors. Therefore, elimination of cancer stem cells is difficult but essential to cure the malignant foci completely. Herein, we review the recent evidence for intestinal stem cells and colon cancer stem cells, methods to detect the tumor-initiating cells, and clinical significance of cancer stem cell markers. We also describe the emerging problems of cancer stem cell theory, including bidirectional conversion and intertumoral heterogeneity of stem cell phenotype.