Folliculostellate cell tumor in pituitary gland

Enhanced EPR effects by tumour stromal cell mimicking nanoplatform on invasive pituitary adenoma

Rapid advances in nanomedicine have enabled potential applications in cancer therapy. The enhanced permeability and retention (EPR) effect is the primary rationale for the passive targeting of nanoparticles in oncology. However, growing evidence indicates that the accumulation of nanomaterials via the EPR effect could be more efficient. Inspired by our clinical observation of the Gap Junction connecpion between folliculostellate cells and pituitary adenoma cells, we designed a novel drug delivery system that targets tumours by coating folliculostellate cell (FS) membranes onto PLGA nanoparticles (NPs). The resulting FSNPs, inheriting membrane proteins from the folliculostellate cell membrane, significantly enhanced the EPR effect compared to nanoparticles without cancer cell membranes. We further demonstrated that mitotane encapsulation improved the therapeutic efficacy of mitotane in both heterotopic and orthotopic pituitary adenoma models. Owing to its significant efficacy, our FS cell membrane-coated nanoplatforms has the potential to be translated into clinical applications for the treatment of invasive pituitary adenoma.

circOMA1-Mediated miR-145-5p Suppresses Tumor Growth of Nonfunctioning Pituitary Adenomas by Targeting TPT1

CONTEXT

Nonfunctioning pituitary adenomas (NFPAs) are the major cause of hypopituitarism and infertility. However, the pathogenesis of NFPAs remains largely unknown. Previous studies have demonstrated the crucial role of miRNAs in the progression of pituitary adenomas. Increasing evidence has indicated that circular RNAs (circRNAs) might mediate miRNA transcriptional activity, providing new insights to study the pathogenesis of NFPAs.

OBJECTIVES

To explore the regulation and activity of the circRNA-miRNA-mRNA axis in the tumorigenesis of NFPAs.

DESIGN

The function of miR-145-5p in NFPAs was investigated invitro and invivo. The mechanical details were explored and potential targets of miR-145-5p were identified. Finally, miR-145-5p-associated circRNAs were functionally recognized and confirmed.

RESULTS

miR-145-5p was markedly decreased in NFPA samples and correlated negatively with NFPA invasiveness. Overexpression of miR-145-5p suppressed NFPA cell proliferation and invasiveness and promoted apoptosis. Further results confirmed that translationally controlled tumor protein (TPT1) is a target of miR-145-5p and mediated the effect of miR-145-5p. TPT1 and its downstream factors Mcl-1 and Bcl-xL were downregulated, and Bax was upregulated by miR-145-5p. Moreover, circOMA1 (hsa_circRNA_0002316) was demonstrated to sponge miR-145-5p, whose suppression on NFPA cells was abrogated by circOMA1 overexpression. circOMA1 silencing exhibited a similar inhibitory effect with miR-145-5p overexpression by downregulating TPT1. We found that circOMA1 could further upregulate Mcl-1 and Bcl-xL and downregulate Bax.

CONCLUSIONS

circOMA1 promotes NFPA progression by acting as the sponge of tumor suppressor miR-145-5p to regulate the TPT1 signaling pathway, revealing a therapeutic target in preventing the tumorigenesis of NFPAs.

Tumor suppression by MEG3 lncRNA in a human pituitary tumor derived cell line

Human clinically non-functioning pituitary adenomas (NFAs) account for approximately 40% of diagnosed pituitary tumors. Epigenetic mutations in tumor suppressive genes play an important role in NFA development. Maternally expressed gene 3 (MEG3) is a long non-coding RNA (lncRNA) and we hypothesized that it is a candidate tumor suppressor whose epigenetic silencing is specifically linked to NFA development. In this study, we introduced MEG3 expression into PDFS cells, derived from a human NFA, using both inducible and constitutively active expression systems. MEG3 expression significantly suppressed xenograft tumor growth in vivo in nude mice. When induced in culture, MEG3 caused cell cycle arrest at the G1 phase. In addition, inactivation of p53 completely abolished tumor suppression by MEG3, indicating that MEG3 tumor suppression is mediated by p53. In conclusion, our data support the hypothesis that MEG3 is a lncRNA tumor suppressor in the pituitary and its inactivation contributes to NFA development.

Spindle cell oncocytoma of the adenohypophysis: two case reports and a review of the literature

Spindle cell oncocytoma (SCO) of the adenohy-pophysis is a rare tumor in the sellar region. Due to its rarity, little information is available regarding SCO. It is often misdiagnosed as another type of sellar tumor. In the present study, two cases of SCO were reported. One patient was a 35-year-old female presenting with decreased visual acuity, amenorrhea and lactation. The other patient was a 62-year-old female with no clear symptoms or signs. Cranial magnetic resonance imaging (MRI) revealed a suprasellar mass with marked homogeneous enhancement in the two cases. A craniotomy was performed to completely resect the tumors. The tumors were immunopositive for vimentin, epithelial membrane antigen (EMA), S-100 and thyroid transcription factor-1 (TTF-1). The tumors were pathologically diagnosed as SCO. No recurrence occurred during the follow-up period of 15–21 months. In the present study, the literature was reviewed and the clinical data, imaging features, intraoperative findings and recurrence of 24 cases were analyzed in the literature as well as the present two cases. The average age of the SCO patients was 58.5 years and no gender preference was observed for the disease. The tumor exhibited homogeneous enhancement on the MRI. The intraoperative assessment revealed that the tumor had a rich blood supply and the SCO tumors were immunopositive for vimentin, S-100, EMA and TTF-1. These findings provided valuable clinical data for the preoperative diagnosis and surgical removal of SCO tumors.

Curcumin suppresses HIF1A synthesis and VEGFA release in pituitary adenomas

Curcumin (diferuloylmethane), a polyphenolic compound derived from the spice plant Curcuma longa, displays multiple actions on solid tumours including anti-angiogenic effects. Here we have studied in rodent and human pituitary tumour cells the influence of curcumin on the production of hypoxia inducible factor 1α (HIF1A) and vascular endothelial growth factor A (VEGFA), two key components involved in tumour neovascularisation through angiogenesis. Curcumin dose-dependently inhibited basal VEGFA secretion in corticotroph AtT20 mouse and lactosomatotroph GH3 rat pituitary tumour cells as well as in all human pituitary adenoma cell cultures (n=32) studied. Under hypoxia-mimicking conditions (CoCl(2) treatment) in AtT20 and GH3 cells as well as in all human pituitary adenoma cell cultures (n=8) studied, curcumin strongly suppressed the induction of mRNA synthesis and protein production of HIF1A, the regulated subunit of the hypoxia-induced transcription factor HIF1. Curcumin also blocked hypoxia-induced mRNA synthesis and secretion of VEGFA in GH3 cells and in all human pituitary adenoma cell cultures investigated (n=18). Thus, curcumin may inhibit pituitary adenoma progression not only through previously demonstrated anti-proliferative and pro-apoptotic actions but also by its suppressive effects on pituitary tumour neovascularisation.

Spindle cell oncocytoma of the pituitary gland with follicle-like component: organotypic differentiation to support its origin from folliculo-stellate cells

Spindle cell oncocytoma (SCO) is a rare, non-adenomatous tumor originating from the anterior pituitary gland. Composed of fusiform, mitochondrion-rich cells sharing several immunophenotypic and ultrastructural properties with folliculo-stellate cells (FSC), SCO has been proposed to represent a neoplastic counterpart of the latter. To date, however, SCO has failed to meet one criterion commonly used in histological-based taxonomy and diagnostics; that of recapitulating any of FSCs' morphologically defined developmental or physiological states. We describe a unique example of SCO wherein a conventional fascicular texture was seen coexisting with and organically merging into follicle-like arrangements. The sellar tumor of 2.7 × 2.6 × 2.5 cm was transphenoidally resected from a 55-year old female. Preoperative magnetic resonance imaging indicated an isointense, contrast enhancing mass with suprasellar extension. Histology showed multiple rudimentary to well-formed, follicle-like cavities on a classical spindle cell background; while all the participating cells exhibited an SCO immunophenotype, including positivity for S100 protein, vimentin, EMA, Bcl-2, and TTF-1, as well as staining with the antimitochondrial antibody 113-1. Conversely no expression of GFAP, follicular-epithelial cytokeratin, carcinoembryonic antigen, or anterior pituitary hormones was detected. Ultrastructurally, tumor cells facing follicular lumina displayed organelles of epithelial specialization, in particular surface microvilli and apical tight junctions. This constellation is felt to be reminiscent of FSCs' metaplastic transition to follicular epithelium, as observed during embryonic development and physiological renewal of the hormone-secreting parenchyma. Such finding is apt to being read as a supporting argument for SCO's descent from the FSC lineage.

Fibroblast growth factor-2 autofeedback regulation in pituitary folliculostellate TtT/GF cells

To investigate paracrine regulation of pituitary cell growth, we tested fibroblast growth factor (FGF) regulation of TtT/GF folliculostellate (FS) cells. FGF-2, and FGF-4 markedly induced cell proliferation, evidenced by induction of pituitary tumor transforming gene-1 (Pttg1) mRNA expression and percentage of cells in S phase. Signaling for FGF-2-induced FS cell proliferation was explored by specific pharmacological inhibition. A potent inhibitory effect on FGF-2 action was observed by blocking of Src tyrosine kinase with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d] pyrimidine (>or=0.1 microm), followed by protein kinase C (PKC) inhibition with GF109203X. Treatment with FGF-2 (30 ng/ml; 10 min) activated phosphorylation of signal transducer and activator of transcription-3, ERK, stress-activated protein kinase/c-Jun N-terminal kinase, Akt, and focal adhesion kinase. Src inhibition with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d] pyrimidine suppressed FGF-2-induced Akt and focal adhesion kinase, indicating effects downstream of FGF-2-induced Src activation. FGF-2 also markedly induced its own mRNA expression, peaking at 2-4 h, and this effect was suppressed by Src tyrosine kinase inhibition. The PKC inhibitor GF109203X abolished FGF-2 autoinduction, indicating PKC as the primary pathway involved in FGF-2 autoregulation in these cells. In addition to pituitary FGF-2 paracrine activity on hormonally active cells, these results show an autofeedback mechanism for FGF-2 in non-hormone-secreting pituitary FS cells, inducing cell growth and its own gene expression, and mediated by Src/PKC signaling.