FHL2 suppresses growth and differentiation of the colon cancer cell line HT-29.

Four and a half LIM domain protein 2 (FHL2) can interact with many proteins and regulates different cellular processes, including proliferation and differentiation. FHL2 expression is often deregulated in cancer and may act as both tumor-promoter or tumor-suppressor depending on the type of cancer. Thus, a previous study found that increased FHL2 expression in colon cancer and suppression of FHL2 in a colon cancer cell line with endogenously high FHL2 expression inhibited tumor growth. We applied the opposite strategy, an FHL2 expression plasmid was stably transfected into HT-29 cells, a colon carcinoma cell line which exhibits very low basal levels of FHL2. Stable expression of FHL2 in HT-29 cells induced a G2/M arrest and inhibited anchorage-dependent and -independent growth in vitro. Further, FHL2 expressing HT-29 cell clones revealed significantly higher expression of the differentiation marker E-cadherin but reduced activity of the transcription factor NF-kappaB, which is known to promote colon cancer progression. These findings further underscore the complex role of FHL2 in tumorigenicity, with even different effects on cellular functions of cancer cell lines derived from the same type of tumor and distinctly suggest caution regarding therapeutic strategies targeting FHL2 to treat (colon) cancer.