Characterization of morphological alterations in micropapillary adenocarcinoma of the lung using an established cell line.

Micropapillary adenocarcinoma of the lung is a type of cancer associated with a poor prognosis and is characterized by the presence of tumor cells with a ring‑like glandular structure floating within alveolar spaces. In the present study, the association between its morphological, biochemical and immunohistochemical characteristics, and malignancy was investigated using the KU‑Lu‑MPPt3 cell line established from a patient with MIP adenocarcinoma. Two subpopulations of KU‑Lu‑MPPt3 cells, namely adhesive (AD) and clumpy and suspended (CS) cells, were prepared and subjected to DNA microarray, reverse transcription‑quantitative PCR, western blot and immunostaining analyses. Protein expression patterns were compared between the cell types and their derived tissues using immunostaining. The results revealed similar protein expression patterns between the tumor cells found in the alveolar spaces and CS cells, which exhibited morphological characteristic of MIP adenocarcinoma. Based on the results of DNA microarray analysis, the present study then focused on Akt and focal adhesion kinase (FAK), which were markedly activated in the KU‑Lu‑MPPt3 CS and AD cells, respectively. Following KU‑Lu‑MPPt3 CS cell plating onto collagen‑coated culture dishes, some cells exhibited a transformation of their morphology into KU‑Lu‑MPPt3 AD‑like cells within a few days, and their Akt and FAK activities were similar to those of the AD cells. Additionally, the inhibition of Akt and FAK activities with Akt and FAK inhibitors reduced KU‑Lu‑MPPt3 CS cell adhesion and proliferation. Thus, the aforementioned results indicated that the phosphorylation of FAK and Akt may play a crucial role in the regulation of KU‑Lu‑MPPt3 CS cell adhesion and proliferation, respectively. Furthermore, the malignant potential of MIP adenocarcinoma may be attributed to these morphological and biochemical alterations in the KU‑Lu‑MPPt3 cells.