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Open Access Highly Accessed Research article

Constitutive AKT activation in follicular lymphoma

Ouardia I Yahiaoui123459*, Jacques A Nunès1234, Céline Castanier1234, Raynier Devillier146, Florence Broussais6, Aurélie J Fabre78, Dalila Naimi5, Réda Bouabdallah6, Daniel Olive1234 and Luc Xerri12347

Author Affiliations

1 Inserm, U1068, Centre de Recherche en Cancérologie de Marseille, Marseille, France

2 Institut Paoli-Calmettes, Marseille, France

3 CNRS, UMR7258, Centre de Recherche en Cancérologie de Marseille, Marseille, France

4 Aix-Marseille Université, Marseille, France

5 Université Constantine 1, Laboratoire de génie microbiologique et applications, équipe de biologie physiologie cellulaire et moléculaire, Constantine, Algeria

6 Institut Paoli-Calmettes, Department of Hematology, Marseille, France

7 Institut Paoli-Calmettes, Department of Biopathology, Marseille, France

8 Present Address: Inserm UMR S910, Department of Medical Genetics and Functional Genomics, Faculté de la Timone, 27 Bd Jean Moulin, 13005 Marseille, France

9 Centre de Recherche en Cancérologie de Marseille, 27 Bd Leï Roure -BP 30059, 13273 Marseille cedex 9, France

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BMC Cancer 2014, 14:565  doi:10.1186/1471-2407-14-565

Published: 5 August 2014

Abstract

Background

The phosphoinositide 3- kinase (PI3K) pathway is involved in the growth of various human cancers, including lymphoid malignancies. However its role in the pathogenesis of follicular lymphoma (FL) has not been yet described.

Methods

To clarify this point, biopsy tissue samples from 38 human FL cases were investigated for PIK3CA somatic mutations in exon 9 and 20 using direct sequencing. The same samples were analyzed using western blotting and immunohistochemistry to detect expression of AKT, phosphorylated AKT (pAKT), and PTEN proteins. Two cases of benign lymphadenitis were used as controls.

Results

AKT expression was present in all FL and lymphadenitis cases. 14/38 (37%) FL and 2/2 lymphadenitis cases expressed pAKT. 9/38 (24%) FL samples showed high level of pAKT, whereas 5/38 (13%) FL cases and 2/2 benign lymphadenitis samples expressed low level of pAKT. PTEN expression was observed in 30/38 (79%) FL and 2/2 benign lymphadenitis cases, whereas 8/38 (21%) FL cases showed loss of PTEN expression. 3 cases with positive pAKT did not express PTEN. PIK3CA mutations were not detected in any sample.

Conclusions

These data suggest that the PI3K/AKT signaling pathway could be activated in a subset of FL cases, due to either AKT phosphorylation or PTEN downregulation, in the absence of PIK3CA mutations.

Keywords:
Follicular lymphoma; PIK3CA mutations; AKT phosphorylation; PTEN