Methylation-associated silencing of SFRP1 gene in high-grade serous ovarian carcinomas.

Wnt is a highly conserved signaling pathway responsible for tissue regeneration, maintenance and differentiation of stem cells in adults. Its aberrant activation through reduced expression of Wnt signaling pathway inhibitors, such as proteins from the SFRP family, is commonly seen in many tumors. In the present study we explored SFRP1 protein expression using immunohistochemistry in 11 low-grade serous ovarian carcinomas (LGSC), 42 high-grade serous ovarian carcinomas (HGSC), and 5 normal ovarian tissues (controls). SFRP1 gene methylation was analyzed by methylation-specific PCR in 8 LGSCs, 13 HGSCs and control samples. SFRP1 gene was unmethylated and SFRP1 protein expression was strong in normal ovaries (n=5). Although SFRP1 gene was unmethylated in almost all of the LGSC cases (7/8, 88%), SFRP1 protein expression was significantly lower than in normal ovaries (p<0.05). Seven out of 13 HGSCs (54%) showed SFRP1 gene hypermethylation and protein expression level was also significantly lower than in normal ovaries (p<0.001). Our preliminary data show loss of SFRP1 protein expression caused by the SFRP1 promoter hypermethylation in a subset of HGSCs. SFRP1 protein expression was also lost in LGSCs but different regulatory mechanisms may be involved. Further studies should elucidate the clinical and therapeutic relevance of the observed molecular alterations.

Dishevelled family proteins in serous ovarian carcinomas: a clinicopathologic and molecular study.

Dishevelled family proteins (DVL1, DVL2, and DVL3) are cytoplasmic mediators involved in canonical and non-canonical Wnt signaling that are important for embryonic development. Since Wnt signaling promotes cell proliferation and invasion, its increased activation is associated with cancer development as well. To get deeper insight into the behavior of Dishevelled proteins in cancer, we studied their expression in serous ovarian carcinomas [both low- (LGSC) and high-grade (HGSC)], and HGSC cell lines OVCAR5, OVCAR8, and OVSAHO. DVL protein expression in serous ovarian carcinomas tissues was analyzed using immunohistochemistry, while DVL protein and mRNA expressions in HGSC cell lines were analyzed using Western blot and quantitative real-time PCR. DVL1 protein expression was significantly higher in LGSC compared with normal ovarian tissue, while DVL3 was overexpressed in both LGSC and HGSC. DVL2 and DVL3 protein expression was higher in HGSC cell lines when compared with normal control cell line FNE1, while DVL1, DVL2, and DVL3 mRNA expression was significantly increased only in OVSAHO cell line. Survival analysis revealed no significant impact of DVL proteins on patients' outcome. Our data show an active involvement of Dishevelled family proteins in serous ovarian carcinomas. Further studies should confirm the clinical relevance of these observations.

The role of the Hedgehog signaling pathway in cancer: A comprehensive review.

The Hedgehog (Hh) signaling pathway was first identified in the common fruit fly. It is a highly conserved evolutionary pathway of signal transmission from the cell membrane to the nucleus. The Hh signaling pathway plays an important role in the embryonic development. It exerts its biological effects through a signaling cascade that culminates in a change of balance between activator and repressor forms of glioma-associated oncogene (Gli) transcription factors. The components of the Hh signaling pathway involved in the signaling transfer to the Gli transcription factors include Hedgehog ligands (Sonic Hh [SHh], Indian Hh [IHh], and Desert Hh [DHh]), Patched receptor (Ptch1, Ptch2), Smoothened receptor (Smo), Suppressor of fused homolog (Sufu), kinesin protein Kif7, protein kinase A (PKA), and cyclic adenosine monophosphate (cAMP). The activator form of Gli travels to the nucleus and stimulates the transcription of the target genes by binding to their promoters. The main target genes of the Hh signaling pathway are PTCH1, PTCH2, and GLI1. Deregulation of the Hh signaling pathway is associated with developmental anomalies and cancer, including Gorlin syndrome, and sporadic cancers, such as basal cell carcinoma, medulloblastoma, pancreatic, breast, colon, ovarian, and small-cell lung carcinomas. The aberrant activation of the Hh signaling pathway is caused by mutations in the related genes (ligand-independent signaling) or by the excessive expression of the Hh signaling molecules (ligand-dependent signaling - autocrine or paracrine). Several Hh signaling pathway inhibitors, such as vismodegib and sonidegib, have been developed for cancer treatment. These drugs are regarded as promising cancer therapies, especially for patients with refractory/advanced cancers.