The Secretomes of Painful Versus Nonpainful Human Schwannomatosis Tumor Cells Differentially Influence Sensory Neuron Gene Expression and Sensitivity

Abstract

Schwannomatosis is a multiple tumor syndrome in which patients develop benign tumors along peripheral nerves throughout the body. The first symptom with which schwannomatosis patients often present, prior to discovery of tumors, is pain. This pain can be debilitating and is often inadequately alleviated by pharmacological approaches. Schwannomatosis-associated pain can be localized to the area of a tumor, or widespread. Moreover, not all tumors are painful, and the occurrence of pain is often unrelated to tumor size or location. We speculate that some individual tumors, but not others, secrete factors that act on nearby nerves to augment nociception by producing neuronal sensitization or spontaneous neuronal firing. We created cell lines from human SWN tumors with varying degrees of pain. We have found that conditioned medium (CM) collected from painful SWN tumors, but not that from nonpainful SWN tumors, sensitized DRG neurons, causing increased sensitivity to depolarization by KCl, increased response to noxious TRPV1 and TRPA1 agonists and also upregulated the expression of pain-associated genes in DRG cultures. Multiple cytokines were also detected at higher levels in CM from painful tumors. Taken together our data demonstrate a differential ability of painful versus non-painful human schwannomatosis tumor cells to secrete factors that augment sensory neuron responsiveness, and thus identify a potential determinant of pain heterogeneity in schwannomatosis. . Patients with schwannomatosis (SWN) develop multiple tumors along major nerves of the body 1 . In most cases the tumor burden is so great that they cannot be removed by surgical intervention 2 . Sixty-eight percent of SWN patients also report chronic pain, which is often debilitating 3 . Pain in SWN has been described as localized in some patients and diffuse in others 4 . The size and location of the tumor(s) do not necessarily relate to the severity of pain experienced by the patient 5 . Thus, while surgical removal of an individual tumor may provide pain relief in some cases, the surgeon is challenged with which tumor to remove. Additional confounding factors (e.g., nerve deficits, tumor recurrence, return of pain) may also affect surgical outcome 6,7 . Quality of life in Schwannomatosis patients is predominantly affected by pain, especially in those with a large tumor burden. Therefore, treatment approaches other than tumor-focused surgery needs to be developed.Neuropathic, nociceptive, and inflammatory types of pain have all been reported in SWN. The pain described by SWN patients can vary from burning to pain that feels like electric shocks 8,9 . Yet, the molecular mechanisms by which some SWN tumors, but not others, elicit unremitting pain are unknown 3 . Given the close interactions between Schwann cells and neurons, we have chosen to study the potential role of Schwann cells in neuropathic pain in schwannomatosis. It is well documented that in models of peripheral nerve injury, Schwann cells become activated and release soluble pro-inflammatory cy...

Conditioned medium from painful schwannomatosis tumors increases pain behaviors in mice

“…Our prior study focused on deciphering the molecular mechanisms of painful tumors (Pain score >7) compared to "non-painful" tumors (pain score <3) [10]. Those in vitro experiments revealed that CM collected from painful SWN tumors, but not that from nonpainful SWN tumors, contained increased amounts of multiple cytokines, upregulated the expression of pain-associated genes in sensory neuron cultures, and increased neuronal responses to noxious TRPV1 and TRPA1 agonists [10]. In the present study, these and additional CM samples were injected in vivo to assess whether the secretome of SWN cells can induce painful behaviors in mice.…”

Analysis of Imaging and Pathological Features in 12 Cases of Schwannomatosis and Literature Review

“…Ding et al [10] suggest that the structural and functional abnormalities of the SMARCB1 gene might be the molecular basis of familial schwannomatosis. If the focus involves peripheral-nerve tissue, it can be accompanied by pain [11]. Jordan et al [12], using a simple 10-point pain scale (SF-36) to explore the relationship between pain and mutation of the SMARCB1 and LZTR1 genes in schwannomatosis, found that the median pain score of the LZTR1 group was 3.9 and that of the SMARCB1 group was 0.5 (P = 0.0414).…”

LZTR1‐related spinal schwannomatosis and 7q11.23 duplication syndrome: A complex phenotype with dual diagnosis

“…Painful tumors in schwannomatosis secrete factors that act on nearby nerves to augment nociception by producing neuronal sensitization or spontaneous neuronal firing, as evidenced by the work done in cell lines of painful and non‐painful tumors (Ostrow et al, 2019). Increased sensitivity to depolarization by KCl, increased response to noxious TRPV1 and TRPA1 agonists, and upregulation of pain‐associated gene expression were found in the DRG cultures (Ostrow et al, 2019). In 7q11.23 duplication syndrome, one‐fourth of parents reported high pain tolerance in their affected children (Morris et al, 2015).…”