Sbaffone Maddalena, Jaffrain-Rea Marie-Lise, Cappabianca Lucia, Carbonara Francesca, Gianno Francesca, Feola Tiziana, Ruggieri Marianna, Zelli Veronica, Maccarone Rita, Guadagni Stefano, Clementi Marco, Arcella Antonietta, Esposito Vincenzo, Carozza Giulia, Martelli Ilaria, Farina Antonietta Rosella, Mackay Andrew Reay
Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio, 67100 L'Aquila, Italy.
Neuromed, Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS), 86077 Pozzilli, Italy.
Biology (Basel). 2024 Mar 7;13(3):171. doi: 10.3390/biology13030171.
Pituitary neuroendocrine tumors (PitNETs) are generally benign but comprise an aggressive, invasive, therapy-resistant, metastatic subset, underpinning a need for novel therapeutic targets. PitNETs exhibit low mutation rates but are associated with conditions linked to alternative splicing, an alternative oncogene pathway activation mechanism. PitNETs express the neurotrophin receptor TrkA, which exhibits oncogenic alternative splicing in other neuroendocrine tumors. We, therefore, assessed whether splicing represents a potential oncogenic participant in PitNETs. splicing was RT-PCR assessed in 53 PitNETs and TrkA isoform(s) expression and activation were assessed by confocal immunofluorescence. splicing was also compared to HIF1α, HIF2α, SF3B1, SRSF2, U2AF1, and JCPyV large T antigen mRNA expression, Xbp1 splicing, and mutation. splicing was detected in all invasive and most non-invasive PitNETs and was significantly elevated in invasive cases. In PitNET lineages, splicing was significantly elevated in invasive PIT1 PitNETs and high in invasive and non-invasive SF1 and TPIT lineages. Immunoreactivity consistent with TrkAIII activation characterized PitNET expressing mRNA, and invasive Pit1 PitNETs exhibited elevated expression. splicing did not associate with mutations, altered , , and or JCPyV large T antigen expression, or Xbp1 splicing. Therefore, splicing is common in PitNETs, is elevated in invasive, especially PIT1 tumors, can result in intracellular TrkAIII activation, and may involve hypoxia. The data support a role for splicing in PitNET pathogenesis and progression and identify TrkAIII as a novel potential target in refractory PitNETs.
垂体神经内分泌肿瘤（PitNETs）通常为良性，但包含具有侵袭性、转移性、治疗抵抗性的亚组，这表明需要新的治疗靶点。PitNETs的突变率较低，但与替代剪接相关的情况有关，替代剪接是一种替代的致癌基因途径激活机制。PitNETs表达神经营养因子受体TrkA，其在其他神经内分泌肿瘤中表现出致癌性替代剪接。因此，我们评估了替代剪接是否代表PitNETs中潜在的致癌参与者。通过逆转录聚合酶链反应（RT-PCR）评估了53例PitNETs中的替代剪接，并通过共聚焦免疫荧光评估了TrkA异构体的表达和激活。还将替代剪接与缺氧诱导因子1α（HIF1α）、缺氧诱导因子2α（HIF2α）、剪接因子3B亚基1（SF3B1）、丝氨酸/精氨酸丰富剪接因子2（SRSF₂）、U2辅助因子1（U2AF1）和多瘤病毒大T抗原mRNA表达、X盒结合蛋白1（Xbp1）剪接以及替代剪接突变进行了比较。在所有侵袭性和大多数非侵袭性PitNETs中均检测到替代剪接，且在侵袭性病例中显著升高。在PitNET谱系中，替代剪接在侵袭性垂体特异性转录因子1（PIT1）PitNETs中显著升高，在侵袭性和非侵袭性类固醇生成因子1（SF1）和垂体特异性转录因子（TPIT）谱系中较高。与TrkAIII激活一致的免疫反应性是表达替代剪接mRNA的PitNET的特征，侵袭性Pit1 PitNETs表现出升高 的替代剪接表达。替代剪接与替代剪接突变、缺氧诱导因子1α、缺氧诱导因子2α、剪接因子3B亚基1、丝氨酸/精氨酸丰富剪接因子2或多瘤病毒大T抗原表达改变或Xbp1剪接无关。因此，替代剪接在PitNETs中很常见，在侵袭性肿瘤尤其是PIT1肿瘤中升高，可导致细胞内TrkAIII激活，并且可能涉及缺氧。这些数据支持替代剪接在PitNET发病机制和进展中的作用，并将TrkAIII确定为难治性PitNETs中的一个新的潜在靶点。
