RESUMEN

Cancer patients often experience changes in mental health, prompting an exploration into whether nerves infiltrating tumors contribute to these alterations by impacting brain functions. Using a mouse model for head and neck cancer and neuronal tracing, we show that tumor-infiltrating nerves connect to distinct brain areas. The activation of this neuronal circuitry altered behaviors (decreased nest-building, increased latency to eat a cookie, and reduced wheel running). Tumor-infiltrating nociceptor neurons exhibited heightened calcium activity and brain regions receiving these neural projections showed elevated Fos as well as increased calcium responses compared to non-tumor-bearing counterparts. The genetic elimination of nociceptor neurons decreased brain Fos expression and mitigated the behavioral alterations induced by the presence of the tumor. While analgesic treatment restored nesting and cookie test behaviors, it did not fully restore voluntary wheel running indicating that pain is not the exclusive driver of such behavioral shifts. Unraveling the interaction between the tumor, infiltrating nerves, and the brain is pivotal to developing targeted interventions to alleviate the mental health burdens associated with cancer.

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A lot of cancer survivors experience a decline in mental health, persisting often decades after successful treatment. Many factors contribute to this reduced mental well-being, including the physical, emotional and financial stresses they experience. Scientists think that the increased prevalence of mental health disorders among cancer patients and survivors may also be linked to the cancer itself. Previous research has shown that most tumors, in particular in melanomas, cervical and ovarian cancers, and head and neck cancers, contain sensory nerves that sense thermal, mechanical and chemical changes and so alert an organism about a potential danger, such as extreme temperature, pressure, changes in pH or inflammation. To investigate whether these nerves contribute to the worsened mental health of cancer patients, Barr, Walz et al. studied male mice with tumors growing in their mouths, mimicking the disease of patients with head and neck cancers. The mice with tumors exhibited several altered behaviors linked to their well-being, suggesting that they had reduced overall health compared to mice without tumors. For example, they were less inclined to build nests, accept treats or run on a wheel. Next, Barr, Walz et al. injected a fluorescent dye into the tumors to label the nerves inside the cancerous growths. Fluorescence microscopy and imaging studies revealed that, days later, the dye had traveled to multiple regions of the brain, indicating that the nerves in the tumors had connected to a preexisting nerve circuit that included these brain regions. Further experiments revealed that the nerve cells in these brain regions were more active in mice with tumors and had different functional properties compared to mice without tumors. Removing the connecting nerves either genetically or with a drug improved all the behaviors of the mice with tumors. Treating the mice with painkillers also improved some but not all of their behaviors, indicating that pain is not the exclusive driver of such behavioral shifts. These two experiments suggest that the nerves from the tumors relay information about pain to the brain and contribute to reduced well-being of the mice. Further studies will test whether these tumor-brain connections also contribute to behavioral changes in mice with other types of cancer. The data suggest that disrupting the neural connections between a tumor and the brain may improve the mental health of patients with cancer, but more research is needed to establish this link.

Asunto(s)

Encéfalo , Modelos Animales de Enfermedad , Neoplasias de Cabeza y Cuello , Animales , Ratones , Neoplasias de Cabeza y Cuello/fisiopatología , Conducta Animal , Neuronas/fisiología , Neuronas/metabolismo , Ratones Endogámicos C57BL , Masculino

RESUMEN

Cancer neuroscience is an emerging field of cancer biology focused on defining the interactions and relationships between the nervous system, developing malignancies, and their environments. Our previous work demonstrates that small extracellular vesicles (sEVs) released by head and neck squamous cell carcinomas (HNSCCs) recruit loco-regional nerves to the tumor. sEVs contain a diverse collection of biological cargo, including microRNAs (miRNAs). Here, we asked whether two genes commonly amplified in HNSCC, CCND1, and PIK3CA, impact the sEV miRNA cargo and, subsequently, sEV-mediated tumor innervation. To test this, we individually overexpressed these genes in a syngeneic murine HNSCC cell line, purified their sEVs, and tested their neurite outgrowth activity on dorsal root ganglia (DRG) neurons in vitro. sEVs purified from Ccnd1-overexpressing cells significantly increased neurite outgrowth of DRG compared to sEVs from parental or Pik3ca over-expressing cells. When implanted into C57BL/6 mice, Ccnd1 over-expressing tumor cells promoted significantly more tumor innervation in vivo. qPCR analysis of sEVs shows that increased expression of Ccnd1 altered the packaging of miRNAs (miR-15-5p, miR-17-5p, and miR-21-5p), many of which target transcripts important in regulating axonogenesis. These data indicate that genetic amplifications harbored by malignancies impose changes in sEV miRNA cargo, which can influence tumorc innervation.

Asunto(s)

Fosfatidilinositol 3-Quinasa Clase I , Vesículas Extracelulares , Neoplasias de Cabeza y Cuello , Ratones Endogámicos C57BL , MicroARNs , Animales , MicroARNs/genética , MicroARNs/metabolismo , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/genética , Ratones , Neoplasias de Cabeza y Cuello/genética , Neoplasias de Cabeza y Cuello/metabolismo , Neoplasias de Cabeza y Cuello/patología , Fosfatidilinositol 3-Quinasa Clase I/genética , Fosfatidilinositol 3-Quinasa Clase I/metabolismo , Línea Celular Tumoral , Ciclina D1/genética , Ciclina D1/metabolismo , Ganglios Espinales/metabolismo , Humanos , Amplificación de Genes , Carcinoma de Células Escamosas de Cabeza y Cuello/genética , Carcinoma de Células Escamosas de Cabeza y Cuello/metabolismo , Carcinoma de Células Escamosas de Cabeza y Cuello/patología

RESUMEN

Cancer patients often experience changes in mental health, prompting an exploration into whether nerves infiltrating tumors contribute to these alterations by impacting brain functions. Using a male mouse model for head and neck cancer, we utilized neuronal tracing techniques and show that tumor-infiltrating nerves indeed connect to distinct brain areas via the ipsilateral trigeminal ganglion. The activation of this neuronal circuitry led to behavioral alterations represented by decreased nest-building, increased latency to eat a cookie, and reduced wheel running. Tumor-infiltrating nociceptor neurons exhibited heightened activity, as indicated by increased calcium mobilization. Correspondingly, the specific brain regions receiving these neural projections showed elevated cFos and delta FosB expression in tumor-bearing mice, alongside markedly intensified calcium responses compared to non-tumor-bearing counterparts. The genetic elimination of nociceptor neurons in tumor-bearing mice led to decreased brain Fos expression and mitigated the behavioral alterations induced by the presence of the tumor. While analgesic treatment successfully restored behaviors involving oral movements to normalcy in tumor-bearing mice, it did not have a similar therapeutic effect on voluntary wheel running. This discrepancy points towards an intricate relationship, where pain is not the exclusive driver of such behavioral shifts. Unraveling the interaction between the tumor, infiltrating nerves, and the brain is pivotal to developing targeted interventions to alleviate the mental health burdens associated with cancer. Significance Statement: Head and neck cancers are infiltrated by sensory nerves which connect to a pre-existing circuit that includes areas in the brain. Neurons within this circuit are altered and mediate modifications in behavior.