DNA methylation transcriptionally regulates the putative tumor cell growth suppressor ZNF677 in non-small cell lung cancers

In our study, we investigated the role of ZNF677 in non-small cell lung cancers (NSCLC). By comparing ZNF677 expression in primary tumor (TU) and in the majority of cases also of corresponding non-malignant lung tissue (NL) samples from > 1,000 NSCLC patients, we found tumor-specific downregulation of ZNF677 expression (adjusted p-values < 0.001). We identified methylation as main mechanism for ZNF677 downregulation in NSCLC cells and we observed tumor-specific ZNF677 methylation in NSCLC patients (p < 0.0001). In the majority of TUs, ZNF677 methylation was associated with loss of ZNF677 expression. Moreover, ZNF677 overexpression in NSCLC cells was associated with reduced cell proliferation and cell migration. ZNF677 was identified to regulate expression of many genes mainly involved in growth hormone regulation and interferon signalling. Finally, patients with ZNF677 methylated TUs had a shorter overall survival compared to patients with ZNF677 not methylated TUs (p = 0.013). Overall, our results demonstrate that ZNF677 is trancriptionally regulated by methylation in NSCLCs, suggest that ZNF677 has tumor cell growth suppressing properties in NSCLCs and that ZNF677 methylation might serve as prognostic parameter in these patients

Tumor-suppressive function of mutated gelsolin in ras-transformed cells

The flat revertant R1, isolated from human activated Ha-ras oncogene-transformed NIH3T3 fibroblasts (EJ-NIH3T3), expresses a variant form of the actin-regulatory protein gelsolin (p92-5.7). We have cloned CDNAS encoding p92-5.7 and identified as the cause of the expression of p92-5.7 a point mutation in codon 321, which results in an amino acid change from proline to histidine. In order to understand the role of p92-5.7 in reversion of ras-transformed cells, CDNAS encoding p92-5.7 or human authentic gelsolin as a control were transfected into EJ-NIH3T3 cells. All the transfectants that produced p92-5.7 and one of three transfectants that produced human authentic gelsolin either lost or reduced tumorigenicity in syngeneic mice. These results demonstrate that mutated gelsolin can suppress a ras tumor and suggest that authentic gelsolin, if expressed at increased levels, may have a similar suppressive potential. Our data propose an important role for gelsolin in cellular signal transduction pathways that involve the mammalian ras proto-oncogene

Gelsolin: a candidate for suppressor of human bladder cancer

Human transitional cell carcinomas of the bladder frequently reveal chromosomal abnormalities that span a range between chromosome 9pl2 and 9qter, even at early stages of bladder carcinogenesis. Because the gene that encodes an actin-regulatory protein, gelsolin, is localized in chromosome 9q33, we examined the expression of gelsolin in a number of human bladder cancer cell lines and tissues. In all 6 cell lines and in 14 of the 18 tumor tissues (77.8%), gelsolin expression was undetectable or extremely low in comparison with its expression in normal bladder epithelial cells. Furthemore, upon the introduction of the exogenous human or mouse authentic gelsolin cDNA into a human bladder cancer cell line, UMUC-2, gelsolin transfectants of UMUC-2 greatly reduced the colony-forming ability and the tumorigenicity in vivo. These results suggest that gelsolin plays a key role as a tumor suppressor in human urinary bladder carcinogenesis