PIK3CA Mutations in Resected Small Cell Lung Cancer.

Background: Despite advances in chemotherapy and radiotherapy in recent decades, the prognosis for small cell lung cancer (SCLC) patients is still poor. Targeted therapies in SCLC must be applied systemically to target not only the primary tumor but also metastases. The phosphatidylinositol 3-kinase (PI3K)/AKT pathways play a key regulatory function in the survival, proliferation, energy metabolism and cellular architecture advantages of malignant cells. The phosphatidylinositol 3-kinase catalytic α (PIK3CA) gene, which encodes the p110α catalytic subunit, plays a key role in the activation of AKT downstream signaling and mammary tumor progression. More than 75% of PIK3CA mutations are clustered in the helical (exon 9) and catalytic domains (exon 20). There have been very few studies reporting the PIK3CA mutations status of patients with SCLC who have undergone surgical treatment in mainland China.

Objectives: The aim of the study was to investigate the PIK3CA mutation in SCLC.

Material And Methods: Reverse transcription polymerase chain reaction (RT-PCR) and direct sequencing technology was used to detect the PIK3CA mutation in 14 cases of retrospectively collected SCLC patients who underwent surgical treatment at Zhejiang Cancer Hospital, Hangzhou, PRC, between 2002 and 2010.

Results: The research revealed no mutations in exons 9 and 20 of the PIK3CA gene. A nucleotide alteration of A1634C (E545A) of exon 9 turned out to be a pseudogene-positive, because the mutation disappeared when near-duplicate detection was employed.

Conclusions: The incidence of PIK3CA mutation is low in SCLC patients, and the pseudogene-positive alteration of A1634C is prone to occur in exon 9 of PIK3CA mutations in human cancers.