Primary cilia in gastrointestinal stromal tumors

Abstract

The primary cilium is a solitary, sensory, non-motile microtubule-based structure that arises from the centrosome and is projected from the surface of most human cells. The objective of the current pilot study was to conduct an investigation of presence and frequency of cilia in gastrointestinal stromal tumors (GIST).The presence of primary cilia in GIST was evaluated in 9 patients, including 8 primary tumors and 1 liver metastasis. In 2 patients the presence of primary cilia was evaluated not only in the primary tumor, but also in recurrence: in 1 patient in recurrence without previous treatment with imatinib and in 1 patient in recurrence after treatment with imatinib. The primary cilia of GIST cells were immunofluorescently stained with primary monoclonal anti-acetylated tubulin alpha antibody and cell nuclei with DAPI.We observed 9985 nuclei of cells of GISTs and 425 primary cilia in total. The median of frequency of primary cilia in cells of GISTs in all examined samples was 4.26%, in primary tumors was 4.32% and in metastases was 3.64%, respectively.This pilot study provides the evidence of the presence of primary cilia in GISTs in different organs. Primary cilia were identified in all examined cases of GIST, including primary tumors, metastases and recurrent lesions without and with previous treatment with imatinib.

Hedgehog pathway dysregulation contributes to the pathogenesis of human gastrointestinal stromal tumors via GLI-mediated activation of KIT expression

“…For IFT trafficking to occur, the microtubule plus-end directed motor kinesin-II (including KIF3A) and the IFT-B protein complex (including IFT52, IFT88, and IFT172) are necessary. We now show that these PC genes are expressed in GIST, consistent with previous reports that primary, recurrent, and metastatic GIST have PC [25, 26]. Thus, ICC and GIST have PC, which are important for Hedgehog and PDGFRA signaling; and GIST overexpress critical PC machinery involved in normal and aberrant PC signaling.…”

“…It is noteworthy that two of these are Hedgehog target genes, namely, PTCH1 and HHIP , function as readouts of pathway activity, and act to fine-tune Hedgehog signals based upon negative feedback loops. Given the reported presence of primary cilia (PC) in GIST [25, 26], as well as the importance of PC in Hedgehog signaling transduction, it is also noteworthy that four proteins responsible for anterograde trafficking of cargo in PC, namely, KIF3A (encoding kinesin family member 3A), IFT52 (intraflagellar transport 52), IFT88 (intraflagellar transport 88), and IFT172 (intraflagellar transport 172), were significantly overexpressed in GIST as compared to ICC (Figure 3B). Overall, the top 7 overexpressed (>16-fold) genes in GIST relative to ICC (in descending order) are HIPK2 (homeodomain-interacting protein kinase 2), IFT52, FOXF1 (forkhead box F1), RB1 (retinoblastoma 1), PtTCH1, RAB23 , and TGFBR2 (transforming growth factor beta receptor II).…”

“…Finally, it is known that optimal Hedgehog signaling in vertebrate cells requires primary cilia (PC) [22]. PC have been reported in murine, rat, rabbit, and human ICC [23, 24], as well as in primary, recurrent and metastatic human GIST [25, 26], possibly developing under the control of the ICC and GIST marker, anoctamin 1 (ANO1) [27]. …”

Functional aspects of primary cilium in signaling, assembly and microenvironment in cancer

“…Studies also found that in subpopulations of cells within human glioblastoma tumors are ciliated (Sarkisian et al, 2014) and human medulloblastoma cells critically rely on the establishment of primary cilia to drive Shh‐mediated cell division (Gate et al, 2015). The presence of primary cilia also been found in the spindle and epithelioid gastric gastrointestinal stromal tumors cells (Castiella et al, 2013; Dvorak et al, 2014), HeLa (human epithelial adenocarcinoma), and other cancer cell lines such as MG63 (human osteosarcoma; Kowal & Falk, 2015), though the significance of this persistent primary cilium in cancer cells still unclear.…”