cyclin-d1 and Fibroma

Plexiform fibromyxoma (PF) is a rare gastric tumor often confused with gastrointestinal stromal tumor. These so-called "benign" tumors often present with upper GI bleeding and gastric outlet obstruction. It was recently demonstrated that approximately one-third of PF have activation of the GLI1 oncogene, a transcription factor in the hedgehog (Hh) pathway, via a MALAT1-GLI1 fusion protein or GLI1 up-regulation. Despite this discovery, the biology of most PFs remains unknown.. Next generation sequencing (NGS) was performed on formalin-fixed paraffin-embedded (FFPE) samples of PF specimens collected from three institutions (UCSD, NCI and OHSU). Fresh frozen tissue from one tumor was utilized for in vitro assays, including quantitative RT-PCR and cell viability assays following drug treatment.. Eight patients with PF were identified and 5 patients' tumors were analyzed by NGS. An index case had a mono-allelic PTCH1 deletion of exons 15-24 and a second case, identified in a validation cohort, also had a PTCH1 gene loss associated with a suspected long-range chromosome 9 deletion. Building on the role of Hh signaling in PF, PTCH1, a tumor suppressor protein, functions upstream of GLI1. Loss of PTCH1 induces GLI1 activation and downstream gene transcription. Utilizing fresh tissue from the index PF case, RT-qPCR analysis demonstrated expression of Hh pathway components, SMO and GLI1, as well as GLI1 transcriptional targets, CCND1 and HHIP. In turn, short-term in vitro treatment with a Hh pathway inhibitor, sonidegib, resulted in dose-dependent cell killing.. For the first time, we report a novel association between PTCH1 inactivation and the development of plexiform fibromyxoma. Hh pathway inhibition with SMO antagonists may represent a target to study for treating a subset of plexiform fibromyxomas.

Topics: Adolescent; Adult; Aged; Carrier Proteins; Chromosome Deletion; Cyclin D1; Exons; Female; Fibroma; Genes, Tumor Suppressor; Hedgehog Proteins; High-Throughput Nucleotide Sequencing; Humans; Male; Membrane Glycoproteins; Middle Aged; Patched-1 Receptor; Retrospective Studies; RNA, Long Noncoding; Smoothened Receptor; Young Adult; Zinc Finger Protein GLI1

CDC73/Parafibromin is a critical component of the Paf1 complex (PAF1C), which is involved in transcriptional elongation and histone modifications. Mutations of the human CDC73/HRPT2 gene are associated with hyperparathyroidism-jaw tumor (HPT-JT) syndrome, an autosomal dominant disorder. CDC73/parafibromin was initially recognized as a tumor suppressor by inhibiting cell proliferation via repression of cyclin D1 and c-myc genes. In recent years, it has also shown oncogenic features by activating the canonical Wnt/β-catenin signal pathway. Here, through limited proteolysis analysis, we demonstrate that the evolutionarily conserved human CDC73 N-terminal 111 residues form a globularly folded domain (hCDC73-NTD). We have determined a crystal structure of hCDC73-NTD at 1.02 Å resolution, which reveals a novel protein fold. CDC73-NTD contains an extended hydrophobic groove on its surface that may be important for its function. Most pathogenic CDC73 missense mutations associated with the HPT-JT syndrome are located in the region encoding CDC73-NTD. Our crystal and biochemical data indicate that most CDC73 missense mutations disrupt the folding of the hydrophobic core of hCDC73-NTD, while others such as the K34Q mutant reduce its thermostability. Overall, our results provide a solid structural basis for understanding the structure and function of CDC73 and its association with the HPT-JT syndrome and other diseases.

Topics: Adenoma; Cell Proliferation; Crystallography, X-Ray; Cyclin D1; Fibroma; Humans; Hydrophobic and Hydrophilic Interactions; Hyperparathyroidism; Jaw Neoplasms; Mutation, Missense; Protein Conformation; Protein Domains; Protein Folding; Proto-Oncogene Proteins c-myc; Surface Properties; Tumor Suppressor Proteins

Primary hyperparathyroidism is primarily due to a solitary parathyroid adenoma but multi-gland disease, parathyroid carcinoma, and ectopic parathyroid hormone production can occur. Although primary hyperparathyroidism mostly presents sporadically, strong familial predispositions also exist. Much is known about heritable genetic mutations responsible for these syndromes, including multiple endocrine neoplasia types 1 and 2A, hyperparathyroidism-jaw tumor syndrome, and familial hypocalciuric hypercalcemia. Acquired mutations in common sporadic hyperparathyroidism have also been discovered. Here we focus on the most common and well-established genetic drivers: 1) involvement of the oncogene cyclin D1 in human neoplasia was first established in parathyroid adenomas, followed by recognition of its importance in other tumor types including breast cancer and B-lymphoid malignancy; and 2) somatic mutation of the

Topics: Adenoma; Cyclin D1; Fibroma; Humans; Hyperparathyroidism; Hyperparathyroidism, Primary; Jaw Neoplasms; Parathyroid Neoplasms; Proto-Oncogene Proteins

We have studied 11 cases of low-grade fibromyxoid sarcoma (LGFMS) and 15 cases of fibromatosis with respect to clinicopathological features and immunohistochemical expression of Ki-67, nm23, cyclinD1, and p53, in order to investigate the differential diagnosis between this two groups. Formalin-fixed, paraffin-embedded sections from 11 cases of LGFMS and 15 cases of fibromatosis were studied histologically and immunohistochemically. The immunostainings were semiquantitatively evaluated using the Allred score system. Microscopically, LGFMS was composed of bland spindle cells arranged in a whorled pattern showing alternating myxoid zones and fibrous stroma zones with prominent arcade curvilinear capillaries. Cytological atypia, mitotic figures, and tumor necrosis were absent in all 11 cases of LGFMS. In contrast, fibromatosis was less cellular and more fascicular, containing more collagen and showing no alternating fibrous and myxoid zones as compared with LGFMS. The immunostaining scores of nm23 in LGFMS were significantly lower than that in fibromatosis. The immunostaining scores of Ki-67, p53, and cyclinD1 in LGFMS were significantly higher than that in fibromatosis. Thus, we consider that LGFMS can be distinguished from fibromatosis by clinicopathological features, and assessments of the immunohistochemical expression level of cyclinD1, p53, nm23, and Ki-67 are helpful in the differential diagnosis.

Topics: Adolescent; Adult; Aged; Cyclin D1; Diagnosis, Differential; Female; Fibroma; Fibrosarcoma; Humans; Ki-67 Antigen; Male; Middle Aged; Neoplasm Staging; NM23 Nucleoside Diphosphate Kinases; Soft Tissue Neoplasms; Tumor Suppressor Protein p53; Young Adult