Many Voices in a Choir: Tumor-Induced Neurogenesis and Neuronal Driven Alternative Splicing Sound Like Suspects in Tumor Growth and Dissemination

Interleukin-17 signaling influences CD8+ T cell immunity and tumor progression according to the IL-17 receptor subunit expression pattern in cancer cells

IL-17 immune responses in cancer are controversial, with both tumor-promoting and tumor-repressing effects observed. To clarify the role of IL-17 signaling in cancer progression, we used syngeneic tumor models from different tissue origins. We found that deficiencies in host IL-17RA or IL-17A/F expression had varying effects on the in vivo growth of different solid tumors including melanoma, sarcoma, lymphoma, and leukemia. In each tumor type, the absence of IL-17 led to changes in the expression of mediators associated with inflammation and metastasis in the tumor microenvironment. Furthermore, IL-17 signaling deficiencies in the hosts resulted in decreased anti-tumor CD8+ T cell immunity and caused tumor-specific changes in several lymphoid cell populations. Our findings were associated with distinct patterns of IL-17A/F cytokine and receptor subunit expression in the injected tumor cell lines. These patterns affected tumor cell responsiveness to IL-17 and downstream intracellular signaling, leading to divergent effects on cancer progression. Additionally, we identified IL-17RC as a critical determinant of the IL-17-mediated response in tumor cells and a potential biomarker for IL-17 signaling effects in tumor progression. Our study offers insight into the molecular mechanisms underlying IL-17 activities in cancer and lays the groundwork for developing personalized immunotherapies.

Vagus innervation in the gastrointestinal tumor: Current understanding and challenges

The vagus nerve (VN) is the main parasympathetic nerve of the autonomic nervous system. It is widely distributed in the gastrointestinal tract and maintains gastrointestinal homeostasis with the sympathetic nerve under physiological conditions. The VN communicates with various components of the tumor microenvironment to positively and dynamically affect the progression of gastrointestinal tumors (GITs). The intervention in vagus innervation delays GIT progression. Developments in adeno-associated virus vectors, nanotechnology, and in vivo neurobiological techniques have enabled the creation of precisely regulated "tumor neurotherapies". Furthermore, the combination of neurobiological techniques and single cell sequencing may reveal more insights into VN and GIT. The present review aimed to summarize the mechanisms of communication between the VN and the gastrointestinal TME and to explore the potential and challenges of VN-based tumor neurotherapy in GITs.

Neural stem cell research in Africa: current realities and future prospects

Neural stem cells (NSCs) are immature progenitor cells that are found in developing and adult brains that have the potential of dividing actively and renewing themselves, with a complex form of gene expression. The generation of new brain cells in adult individuals was initially considered impossible, however, the landmark discovery of human neural stem cells in the hippocampus has been followed by further discoveries in other discreet regions of the brain. Investigation into the current state in Africa of the research and use of NSCs shows relatively limited activities on the continent. Information on the African application of NSCs for modelling disease mechanisms, drug discovery, and therapeutics is still limited. The International Brain Research Organization (IBRO)-African Regional Committee (ARC), with support from the Company of Biologists, and the Movement Disorder Society, sponsored the first African Basic School on NSC in Ibadan, Nigeria, with the vision of bringing together young neuroscientists and physicians across different fields in neuroscience to learn from leaders who have applied NSCs in stem cell research, the pathophysiology of neurodegenerative diseases, neuroanatomy, and neurotherapeutics. Twenty early-career researchers in academic institutions at junior and senior faculty cadres were selected from South Africa, Uganda and Nigeria. The students and organizer of the school, who wrote this review on the state of NSCs research in Africa, recommended the following: (1) other African countries can take a cue from South Africa and Nigeria in probing the phenomena of adult neurogenesis in unique animal species on the continent; (2) Africa should leverage the expertise and facilities of South African scientists and international collaborators in scaling up NSC research into these unique species and (3) Centers of Excellence should be established on the continent to serve as research hubs for training postgraduate students, and facilities for African scientists who trained overseas on NSCs.

Peak density of immature nerve cells occurs with high-grade dysplasia in intraductal papillary mucinous neoplasms of the pancreas

The development of neural structures within tumors is now considered vital for carcinogenesis. However, the time course of this development in human pre-invasive neoplasia has been incompletely described. Therefore, we performed a detailed analysis of nerves across the neoplastic spectrum in resected intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. Histology and multiplexed immunochemistry demonstrated that nerve density increased from low-grade (LG) to high-grade dysplasia (HG) but did not further increase once invasive IPMN (INV IPMN) was present. Higher nerve density correlated with increasing expression of nerve growth factor (NGF) by the tumor cells. Intra-tumoral nerves were immature and lacked markers of sympathetic, parasympathetic, and sensory lineages. Here, we show for the first time the presence of neural precursor cells (NPCs) within the stroma of pancreatic tumors. The density of these doublecortin (DCX)-positive NPCs increased from LG to HG, but not from HG to INV IPMN. We conclude that peak neural density of tumors is reached in high-grade dysplasia (often termed carcinoma in situ) rather than after invasion. These findings suggest that nerve-tumor interactions are important in IPMN progression and may serve as the basis for future mechanistic studies and novel therapeutic modalities. © 2022 The Pathological Society of Great Britain and Ireland.

Tumor Innervation: History, Methodologies, and Significance

The role of the nervous system in cancer development and progression has been under experimental and clinical investigation since nineteenth-century observations in solid tumor anatomy and histology. For the first half of the twentieth century, methodological limitations and opaque mechanistic concepts resulted in ambiguous evidence of tumor innervation. Differential spatial distribution of viable or disintegrated nerve tissue colocalized with neoplastic tissue led investigators to conclude that solid tumors either are or are not innervated. Subsequent work in electrophysiology, immunohistochemistry, pathway enrichment analysis, neuroimmunology, and neuroimmunooncology have bolstered the conclusion that solid tumors are innervated. Regulatory mechanisms for cancer-related neurogenesis, as well as specific operational definitions of perineural invasion and axonogenesis, have helped to explain the consensus observation of nerves at the periphery of the tumor signifying a functional role of nerves, neurons, neurites, and glia in tumor development.

Microbiomics in Collusion with the Nervous System in Carcinogenesis: Diagnosis, Pathogenesis and Treatment

The influence of the naturally occurring population of microbes on various human diseases has been a topic of much recent interest. Not surprisingly, continuously growing attention is devoted to the existence of a gut brain axis, where the microbiota present in the gut can affect the nervous system through the release of metabolites, stimulation of the immune system, changing the permeability of the blood-brain barrier or activating the vagus nerves. Many of the methods that stimulate the nervous system can also lead to the development of cancer by manipulating pathways associated with the hallmarks of cancer. Moreover, neurogenesis or the creation of new nervous tissue, is associated with the development and progression of cancer in a similar manner as the blood and lymphatic systems. Finally, microbes can secrete neurotransmitters, which can stimulate cancer growth and development. In this review we discuss the latest evidence that support the importance of microbiota and peripheral nerves in cancer development and dissemination.