Tumor suppressor genes function by regulating normal cell growth and proliferation. When a tumor suppressor gene is turned off, by mutation, deletion, or blocked expression, cell growth can proceed without safeguards, contributing to cancer cell proliferation.
However, this appears not to be the case in some non-small cell lung carcinomas (NSCLC), in which a tumor suppressor (H-REV107-1) actually promotes cancer cell growth.
The group from the Institute of Pathology, Charite University Medicine Berlin, Berlin; and Max-Delbrueck-Centrum, Berlin, Germany examined whether cellular localization of H-REV107-1 in NSCLC tumor samples is linked with tumor behavior. Strikingly, cytoplasmic localization correlated with decreased patient survival (24 months versus 41 months for nuclear localization).
These data suggested that cytoplasmic H-REV107-1 stimulates cell growth. This was then confirmed by suppression of H-REV107-1 RNA, which inhibited cell proliferation, and overexpression of H-REV107-1 protein, which stimulated cell growth pathways and increased proliferation.
The scientists said that the possibility of using H-REV107-1 as a novel prognostic indicator of tumor aggressiveness is appealing. Lung cancer is responsible for more deaths than any other cancer, with only 15% of patients reaching five-year survival, and non-small cell lung cancer accounts for 75% of all lung cancer.