Higher expression of RhoC is related to invasiveness in non-small cell lung carcinoma

The activation of Rho proteins has been shown to lead to loss of polarity in cancer cells, as well as reorganization of the cytoskeleton and facilitation of cell motility, possibly resulting in their malignant potential. The clinicopathological significance of RhoC, however, is not yet well known in the case of non-small cell lung cancer (NSCLC).

The intratumor expression level of RhoC mRNA was determined and compared with that in adjacent nontumorous lung tissue using quantitative reverse transcription-PCR in 49 patients with NSCLC. The relationship between the level of RhoC transcript and clinicopathological factors was examined. RhoC protein expression was confirmed by immunohistochemistry and Western blot analysis in several cases.

Tumor tissue of NSCLC patients demonstrated a copy number of RhoC mRNA that was well correlated with its protein level in each case and was significantly higher than that found in the corresponding nontumorous lung tissue (2.73 x 10(5) versus 1.13 x 10(4) copies/0.08 micro g mRNA; P < 0.05). Histopathologically positive cases of lymphatic permeation showed a significantly higher copy number of RhoC than negative cases (4.31 x 10(5) versus 1.93 x 10(5) copies/0.08 micro g mRNA; P < 0.05). With regard to venous permeation, the RhoC copy number in positive cases tended to be higher than that seen in negative cases (3.72 x 10(5) versus 2.14 x 10(5) copies/0.08 micro g mRNA; P = 0.06).

This is the first demonstration that the expression level of RhoC is correlated to vascular permeation in NSCLC.