Background: Few screening markers for malignant transformation in borderline ovarian tumors (BOT) have been clearly established. The kinase noncatalytic C-lobe domain containing 1 (KNDC1), a brain-specific Ras guanine nucleotide exchange factor, negatively regulates dendrite growth. However, the biological role and underlying mechanism of KNDC1 in human cancers, including ovarian cancer (OC), remain unknown.
Methods: Gene chip screening was used to detect the expression of KNDC1  mRNA in normal ovarian tissues, BOT tissues, and OC tissues. And results were further validated by RT-qPCR, Western blotting and immunohistochemistry. KNDC1  overexpression and knockdown ovarian cancer cells were established to study the possible pathways that KNDC1 was involved. The effects of KNDC1 on the malignant behaviors of ovarian tumors were also investigated both in vitro and in vivo.
Results: We observed that the expression of KNDC1  mRNA and KNDC1 protein in OC was significantly downregulated compared with BOT. Subsequent investigation revealed that knockdown of KNDC1  enhanced the proliferation of ovarian cancer cells in vitro via induction of ERK1/2 phosphorylation, whereas reinforcing the expression of KNDC1  attenuated the ERK1/2 activity. Similarly, knockdown of KNDC1  also promoted cell proliferation in vivo. Survival analysis showed that lower KNDC1  predicted a poor progression-free survival (PFS) for patients.
Conclusion: Collectively, we conclude that KNDC1 might function as a tumor suppressor in ovarian tumors, inhibiting the proliferation of ovarian cells by suppressing ERK1/2 activity and hindering the malignant transformation of BOT.
Keywords: KNDC1, borderline ovarian tumor, ovarian cancer, tumor marker, malignant transformation