Whole-exome sequencing identifies variants in invasive pituitary adenomas

Abstract

Pituitary adenomas exhibit a wide range of behaviors. The prediction of invasion or malignant behavior in pituitary adenomas remains challenging. The objective of the present study was to identify the genetic abnormalities associated with invasion in sporadic pituitary adenomas. In the present study, the exomes of six invasive pituitary adenomas (IPA) and six non-invasive pituitary adenomas (nIPA) were sequenced by whole-exome sequencing. Variants were confirmed by dideoxynucleotide sequencing, and candidate driver genes were assessed in an additional 28 pituitary adenomas. A total of 15 identified variants were mainly associated with angiogenesis, metabolism, cell cycle phase, cellular component organization, cytoskeleton and biogenesis immune at a cellular level, including 13 variants that occurred as single nucleotide variants and 2 that comprised of insertions. The messenger RNA (mRNA) levels of diffuse panbronchiolitis critical region 1 (DPCR1), KIAA0226, myxovirus (influenza virus) resistance, proline-rich protein BstNI subfamily 3, PR domain containing 2, with ZNF domain, RIZ1 (PRDM2), PR domain containing 8 (PRDM8), SPANX family member N2 (SPANXN2), TRIO and F-actin binding protein and zinc finger protein 717 in IPA specimens were 50% decreased compared with nIPA specimens. In particular, DPCR1, PRDM2, PRDM8 and SPANXN2 mRNA levels in IPA specimens were approximately four-fold lower compared with nIPA specimens (P=0.003, 0.007, 0.009 and 0.004, respectively). By contrast, the mRNA levels of dentin sialophospho protein, EGF like domain, multiple 7 (EGFL7), low density lipoprotein receptor-related protein 1B and dynein, axonemal, assembly factor 1 (LRRC50) were increased in IPA compared with nIPA specimens (P=0.041, 0.037, 0.022 and 0.013, respectively). Furthermore, decreased PRDM2 expression was associated with tumor recurrence. The findings of the present study indicate that DPCR1, EGFL7, the PRDM family and LRRC50 in pituitary adenomas are modifiers of tumorigenesis, and most likely contribute to the development of oncocytic change and to the invasive tumor phenotype.

Keywords: PR domain family; exome sequencing; invasive; pituitary adenomas; variant.

Figure 1.

mRNA levels of (A) DPCR1, (B) KIAA0226, (C) MGAM, (D) MX2, (E) PRB3, (F) PRDM2, (G) PRDM8, (H) SPANXN2, (I) TRIOBP and (J) ZNF717 with variants, which are lower in IPA specimens compared with nIPA specimens. mRNA levels of DPCR1, KIAA0226, MX2, PRB3, PRDM2, PRDM8, SPANXN2, TRIOBP and ZNF717 in IPA specimens were 50% decreased compared with nIPA specimens. In particular, DPCR1, PRDM2, PRDM8, SPANXN2 and ZNF717 mRNA levels in IPA specimens were approximately four-fold lower compared with nIPA specimens (P<0.01). n=3–8. Groups were Normal, IPA and nIPA. nIPA, non-invasive pituitary adenoma; IPA, invasive pituitary adenoma; Normal, normal pituitary; mRNA, messenger RNA; DPCR1, diffuse panbronchiolitis critical region 1; MX2, myxovirus (influenza virus) resistance; PRB3, proline-rich protein BstNI subfamily 3; PRDM2, PR domain containing 2, with ZNF domain, RIZ1; PRDM8, PR domain containing 8; SPANXN2, SPANX family member N2; TRIOBP, TRIO and F-actin binding protein; ZNF717, zinc finger protein 717. *p<0.05; **p<0.01; ***p<0.001.

Figure 2.

mRNA level of (A) DSPP, (B) EGFL7, (C) LRP1B and (D) LRRC50 with variants, which are increased in IPA specimens compared with nIPA specimens. mRNA levels of DSPP, EGFL7 and LRRC50 were increased in IPA compared with in nIPA specimens (P<0.01). n=3–8. Groups were Normal, nIPA and IPA. mRNA, messenger RNA; Normal, normal pituitary; nIPA, non-invasive pituitary adenoma; IPA, invasive pituitary adenoma; DSPP, dentin sialophospho protein; EGFL7, EGF like domain, multiple 7; LRRC50, dynein, axonemal, assembly factor 1. *p<0.05; **p<0.01; ***p<0.001.

Figure 3.

Confocal images show the number of PRDM2-positive puncta in recurrent pituitary adenomas. (A) Normal pituitary; (B) non-invasive pituitary adenoma; (C) inviasive pituitary adenoma. Green, PRDM2; dilution, 1:200. Blue, 4′,6-diamidino-2-phenylindole; dilution, 1:3,000. Scale bar, 50 µm. PRDM2, PR domain containing 2, with ZNF domain, RIZ1.