In-depth proteomics reveals the characteristic developmental profiles of early lung adenocarcinoma with epidermal growth factor receptor mutation

INTRODUCTION

Lung adenocarcinoma progresses stepwise from atypical adenomatous hyperplasia to adenocarcinoma in situ (AIS), followed by minimally invasive adenocarcinoma (MIA), and then obvious invasive adenocarcinoma. In this study, we examined the protein expression profiles of early and epidermal growth factor receptor (EGFR) mutation-positive lung adenocarcinomas.

METHODS

Fifteen cases of small and EGFR mutation-positive adenocarcinomas were collected, including AIS, MIA, and small invasive adenocarcinoma (SIA). We examined their protein expression profiles by tandem mass tag (TMT)-labeling liquid chromatography-mass spectrometry (LC-MS/MS) and compared the results between AIS and MIA versus SIA. The differentially expressed proteins were then verified by Western blot analysis and immunohistochemistry (IHC). The clinicopathological implications of the proteins were also examined by IHC.

RESULTS

A total of 4220 proteins were identified by LC-MS/MS analysis. Pathway analysis of the differentially expressed proteins revealed that pathways related to interferon α/β signaling, glutamate and glutamine metabolism, and gluconeogenesis were upregulated in SIA relative to AIS. Among the 13 differentially expressed proteins, cellular retinoic acid binding protein 2 (CRABP2), delta(24)-sterol reductase (DHCR24), and adenylate kinase 4 (AK4) were expressed significantly more strongly in SIA than in AIS. Patients with high expression of CRABP2, DHCR24, and AK4 showed a significantly poorer outcome than those with low expression.

CONCLUSION

In comparison with AIS, SIA shows differences in several different protein expression pathways. Furthermore, CRABP2, DHCR24, and AK4 are useful IHC markers for diagnosis of lung adenocarcinoma invasiveness and may be associated with malignant progression of AIS.

The conceptual advances of carcinogenic sequence model in high-grade serous ovarian cancer

The present review focuses on the current status of molecular pathology in high-grade serous cancer (HGSC) and preneoplastic conditions. This article reviews the English-language literature on HGSC, precursor, fallopian tubal epithelium, secretory cells, ciliated cells, secretory cell expansion, secretory cell outgrowth (SCOUT), p53 signature, serous tubal intraepithelial carcinoma (STIC), DNA damage and immunohistochemistry in an effort to identify the precursor-carcinoma sequence in HGSC. The majority of HGSC originates from the fimbriated end of the fallopian tube secretory epithelial cells, while the small part of this disease may develop from ovarian cortical inclusion cyst (CIC). A series of morphological changes from normal fallopian epithelium to preneoplastic to neoplastic lesions were concomitant with the multistep accumulation of molecular and genetic alterations. Recent studies provide a stepwise progression of fallopian tubal epithelium to precursor lesions to carcinoma, with the aid of a 'secretory cell-SCE-SCOUT-p53 signature-STIC-HGSC sequence' model. Immunohistochemical markers, including p53, STMN1, EZH2, CCNE1, Ki67 and γ-H2AX, were gradually increased during the SCOUT-p53 signature-STIC-HGSC sequence. Conversely, PAX2 expression was decreased during the early phase of SCOUT development. Potential genes and proteins are involved in the evolutionary trajectory of the precursor-cancer lineage model. In the present review we examined detailed aspects of the molecular changes involved in malignant transformation from fallopian tube epithelium to HGSC. A precursor condition originating in 'field cancerization' may gain a growth advantage, leading to HGSC.