Biomedical subjects

Brent A Orr

Publications and source records attributed to Brent A Orr.

4 recordsLinked to original sources

PubMed2025

Recurrent FGFR2 and PIK3CA Mutations in Sialoblastoma.

PURPOSE: Sialoblastoma is an extremely rare low-grade malignant salivary gland neoplasm that presents at birth or early infancy and has heterogeneous clinical behavior. Due to its rarity, the molecular landscape remains incompletely characterized. We aimed to expand the current understanding of the genetic alterations in sialoblastoma through comprehensive molecular analysis. METHODS: Five sialoblastoma cases were retrieved from four institutional archives. Clinical and pathologic review was performed, and targeted next-generation sequencing was conducted using clinically validated panels. Copy number analysis was performed on four cases. RESULTS: The cohort included five patients with tumors located in parotid gland (n = 2), minor salivary glands (n = 2), and submandibular gland (n = 1). Four patients were diagnosed before 6 months of age. Histologically, all tumors showed solid organoid nests with primitive basaloid cells, dense fibrous stroma, and mitotic activity ranging from 8 to 25 per 10 high-power fields. Recurrent FGFR2 p.C382R variants were identified in 80% (4/5) of cases. Additional alterations were seen in FGFR2 p.C382R mutated tumors, including PIK3CA hotspot mutations in two cases (p.R88Q, p.R38H) and a truncating FGFR2 variant (p.L776Rfs) in one. The single tumor that lacked FGFR2 mutations harbored a CTNNB1 p.I35T variant and showed more favorable histologic features. Copy number analysis revealed recurrent whole-chromosome gains of chromosomes 8, 10, and 11. CONCLUSION: A distinct subset of sialoblastoma has FGFR2 p.C382R hotspot mutation as the predominant driver mutation. Tumors with this mutation tend to have solid growth pattern, aggressive histologic features, and clinical behavior. The identification of concurrent genomic alterations expands the molecular landscape of this rare tumor. The detection of alternative drivers, such as CTNNB1 hotspot mutations typical of basal cell adenoma, also suggests that a subset of sialoblastoma may represent other salivary gland tumors presenting in infancy.

Humans↗

PubMed2005

Estrogen induction of the granzyme B inhibitor, proteinase inhibitor 9, protects cells against apoptosis mediated by cytotoxic T lymphocytes and natural killer cells.

Exposure to estrogens is associated with an increased risk of developing breast, cervical, and liver cancer. Estrogens strongly induce the human granzyme B inhibitor, proteinase inhibitor 9 (PI-9). Because cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells use the granzyme pathway to induce apoptosis of target cells, we tested the ability of activated CTLs and the human NK cell line, YT cells, to lyse human liver cells. Estrogen induction of PI-9 protected the liver cells against CTL and NK cell-mediated, granzyme-dependent, apoptosis. Knockdown of PI-9 by RNA interference blocked the protective effect of estrogen. This work demonstrates that estrogens can act on target cells to control their destruction by immune system cells and shows that induction of PI-9 expression can inhibit both CTL and NK cell-mediated apoptosis. Estrogen induction of PI-9 may reduce the ability of cytolytic lymphocytes-mediated immune surveillance to destroy newly transformed cells, possibly providing a novel mechanism for an estrogen-mediated increase in tumor incidence.

Animals↗

PubMed2004

Folate-mediated targeting of T cells to tumors.

Recently various strategies have been developed to exploit in a clinical setting the well established finding that T cells can specifically recognize and destroy tumor cells. Several independent approaches to the targeting of T cells against cancer have been explored, including the use of bispecific antibodies (anti-T cell/anti-tumor cell) to redirect T cells, vaccines to induce tumor-reactive T cells, and adoptive transfer of ex vivo activated, tumor-reactive T cells. In this review, we focus on studies in which high-affinity folate receptors (FRs) on tumor cells have served as targets for redirecting or enhancing the effectiveness of activated T cells. Bispecific antibody conjugates of folate and antibodies to the T cell receptor (TCR) complex can generate tumor-reactive T cell responses. The development of folate/antibody conjugates specific for the T cell co-stimulatory molecule CD28 could yield activated T cells that recognize endogenous peptide-major histocompatibility complex (MHC) antigens on tumor cells. Finally, we discuss a less investigated area in which high-affinity FRs on macrophages, or other antigen presenting cells (APCs), may provide opportunities in the design of tumor-antigen-specific vaccines.

Adoptive Transfer↗

PubMedDate not supplied

Rapid method for measuring ScFv thermal stability by yeast surface display.

We have characterized a simplified method to determine the relative thermal stability of single-chain antibodies by following the irreversible denaturation of scFv fusions on the surface of yeast by flow cytometry. The method was highly reproducible and correlated well with other methods used to monitor thermal denaturation of the soluble proteins. We found a range of thermal stabilities for wild-type single-chain antibodies with half-maximum denaturation temperatures between 43 and 61 degrees C. The ability to quantitate thermal stability of antibodies or other proteins that are immobilized on the surface of yeast allows rapid comparisons of primary structural information with stability. Thermal denaturation could be a useful parameter to consider in the choice of scFv fragments for various applications.

Amino Acid Sequence↗