PTCH1 gene polymorphisms in ovarian tumors: potential protective role of c.3944T allele

PTCH1 gene variants rs357564, rs2236405, rs2297086 and rs41313327, mRNA and tissue expression in basal cell carcinoma patients from Western Mexico

BACKGROUND

Basal cell carcinoma (BCC) represents about 80% of all cases of skin cancer. The PTCH1 is a transmembrane protein of the Sonic Hedgehog signaling pathway that regulates cell proliferation. Genetic variants in PTCH1 gene have been previously described in association with BCC development. In addition, PTCH1 mRNA and protein expression analysis are also significant to understand its role in skin cancer physiopathology.

METHODS

An analytical cross-sectional study was performed, and a total of 250 BCC patients and 290 subjects from the control group (CG) were included, all born in western Mexico. The genotypes and relative expression of the mRNA were determined by TaqMan® assay. The protein expression was investigated in 70 BCC paraffin-embedded samples with PTCH1 antibodies. Semi-quantitative analysis was performed to determine the expression level in the immunostained cells.

RESULTS

We did not find evidence of an association between PTCH1 rs357564, rs2297086, rs2236405, and rs41313327 genetic variants and susceptibility to BCC. Likewise, no statistically significant differences were found in the comparison of the mRNA level expression between BCC and CG (p > 0.05). The PTCH1 protein showed a low expression in 6 of the analyzed samples and moderate expression in 1 sample. No association was found between genetic variants, protein expression, and demographic-clinical characteristics (p > 0.05).

CONCLUSION

The studied PTCH1 variants may not be associated with BCC development in the Western Mexico population. The PTCH1 mRNA levels were lower in patients with BCC compared to the control group, but its protein was underexpressed in the tissue samples.

Inherited rare and common variants in PTCH1 and PTCH2 contributing to the predisposition to reproductive cancers

PTCH1 and PTCH2 are associated with nevoid basal cell carcinoma syndrome and basal cell carcinoma. We determined the prevalence of their common and rare variants in 877 patients with various reproductive cancers and 296 healthy subjects. Using targeted next-generation sequencing, we found significantly statistical associations of the minor alleles at seven common variants of PTCH1 and PTCH2 with a decreased risk of reproductive cancers (P = 9.69 × 10^-12). Among these variants, two haplotype blocks in high linkage disequilibrium were consisted of rs2277184, rs2066829 and rs2236405 sites at PTCH1 and rs3795720, rs11573590 and rs11211040 sites at PTCH2. Single marker and haplotype-based analysis consistently revealed a decreased risk of reproductive cancers especially breast and prostate cancers in the subjects carrying the minor alleles, and on the contrary, an increased risk for major alleles. Healthy control subjects showed a higher rate of rare variants than that of cancer patients (P = 0.017). Notably, two frameshift variants (p.Ser391* and p.Cys101Alafs*48) of PTCH2 with deleterious effects were found in only four cancer patients. Higher frequencies of variants of PTCH genes might have a protective role against the development of reproductive cancers, whereas rare deleterious variants of PTCH2 might predispose a carrier to reproductive cancers.

Sonic Hedgehog signaling pathway in gynecological and genitourinary cancer (Review)

Cancers of the urinary tract, as well as those of the female and male reproductive systems, account for a large percentage of malignancies worldwide. Mortality is frequently affected by late diagnosis or therapeutic difficulties. The Sonic Hedgehog (SHH) pathway is an evolutionary conserved molecular cascade, which is mainly associated with the development of the central nervous system in fetal life. The present review aimed to provide an in‑depth summary of the SHH signaling pathway, including the characterization of its major components, the mechanism of its upstream regulation and non‑canonical activation, as well as its interactions with other cellular pathways. In addition, the three possible mechanisms of the cellular SHH cascade in cancer tissue are discussed. The aim of the present review was to summarize significant findings with regards to the expression of the SHH pathway components in kidney, bladder, ovarian, cervical and prostate cancer. Reports associated with common deficits and de‑regulations of the SHH pathway were summarized, despite the differences in molecular and histological patterns among these malignancies. However, currently, neither are SHH pathway elements included in panels of prognostic/therapeutic molecular patterns in any of the discussed cancers, nor have the drugs targeting SMO or GLIs been approved for therapy. The findings of the present review may support future studies on the treatment of and/or molecular targets for gynecological and genitourinary cancers.

Adolescent ovarian thecoma presenting as progressive hyperandrogenism: case report and review of the literature

Hyperandrogenism is frequent and under investigated in adolescent girls. A 15-year-6-month-old French girl presented with oligomenorrhea and slowly progressing virilization 2 years post-menarche. Medical history revealed prenatal pesticide exposure through maternal professional activity and recurrent premature thelarche. Severe hirsutism, mild facial acne and clitoromegaly were noted. Serum androgens (testosterone: 94 ng/dL, 4-androstenedione: 8.23 ng/mL) were high and non-classic 21-hydroxylase deficiency was excluded. Pelvic ultrasonography showed a left ovarian mass, confirmed by computed tomography scan. Tumor markers were negative. Laparoscopic surgery was performed. The pathological diagnosis was benign luteinized thecoma. Postoperatively, the menstrual cycle and serum androgens became normal and hirsutism slowly improved. Hyperandrogenism 2 years after menarche should be systematically investigated, even if slowly progressive, since it may be a symptom of a rare virilizing ovarian tumor, like thecoma.

Potential hot spot for de novo mutations in PTCH1 gene in Gorlin syndrome patients: a case report of twins from Croatia

We describe a case of twins with sporadic Gorlin syndrome. Both twins had common Gorlin syndrome features including calcification of the falx cerebri, multiple jaw keratocysts, and multiple basal cell carcinomas, but with different expressivity. One brother also had benign testicular mesothelioma. We propose this tumor type as a possible new feature of Gorlin syndrome. Gorlin syndrome is a rare autosomal dominant disorder characterized by both developmental abnormalities and cancer predisposition, with variable expression of various developmental abnormalities and different types of tumors. The syndrome is primarily caused by mutations in the Patched 1 (PTCH1) gene, although rare mutations of Patched 2 (PTCH2) or Suppressor of Fused (SUFU) genes have also been found. Neither founder mutations nor hot spot locations have been described for PTCH1 in Gorlin syndrome patients. Although de novo mutations of the PTCH1 gene occur in almost 50% of Gorlin syndrome cases, there are a few recurrent mutations. Our twin patients were carriers of a de novo mutation in the PTCH1 gene, c.3364_3365delAT (p.Met1122ValfsX22). This is, to our knowledge, the first Gorlin syndrome-causing mutation that has been reported four independent times in distant geographical locations. Therefore, we propose the location of the described mutation as a potential hot spot for mutations in PTCH1.

Non-canonical Hedgehog signaling activation in ovarian borderline tumors and ovarian carcinomas

Hedgehog signaling pathway has been implicated in the pathology of ovarian cancer, and Survivin (BIRC5) has been suggested as a novel target of this pathway. Herein we investigated the role of Hedgehog signaling pathway and Survivin in ovarian carcinoma and borderline tumor samples. We aimed to determine possible ways of pathway modulation on primary ovarian cancer cells and an established cell line. RNA was extracted from fresh tumors and control tissues and gene expression was examined using qRT-PCR. Pathway activity in cell lines was examined after treatment with cyclopamine, SHH protein, GANT-61 or lithium chloride using qRT-PCR, western blot and confocal microscopy. The difference between control tissue, borderline tumors and carcinomas can be seen in GLI1 and SUFU gene expression, which is significantly higher in borderline tumors compared to carcinomas. SUFU also shows lower expression levels in higher FIGO stages relative to lower stages. BIRC5 is expressed in all tumors and in healthy ovarian tissues compared to our control tissue, healthy fallopian tube samples. Primary cells developed from ovarian carcinoma tissue respond to cyclopamine treatment with a short-term decrease in cell proliferation, downregulation of Hedgehog pathway genes, including BIRC5, and changes in protein dynamics. Stimulation with SHH protein results in increased cell migration, while GLI1 transfection or PTCH1 silencing demonstrate pathway upregulation. The pathway activity can be modulated by LiCl at the GSK3β-SUFU-GLI level, suggesting at least partial non-canonical activation. Downregulation of the pathway with GANT-61 has proved to be more effective than cyclopamine. GLI inhibitors may be a superior treatment option in ovarian cancer compared to SMO inhibitors.

Regulation of human PTCH1b expression by different 5' untranslated region cis-regulatory elements

PTCH1 gene codes for a 12-pass transmembrane receptor with a negative regulatory role in the Hedgehog-Gli signaling pathway. PTCH1 germline mutations cause Gorlin syndrome, a disorder characterized by developmental abnormalities and tumor susceptibility. The autosomal dominant inheritance, and the evidence for PTCH1 haploinsufficiency, suggests that fine-tuning systems of protein patched homolog 1 (PTC1) levels exist to properly regulate the pathway. Given the role of 5' untranslated region (5'UTR) in protein expression, our aim was to thoroughly explore cis-regulatory elements in the 5'UTR of PTCH1 transcript 1b. The (CGG)n polymorphism was the main potential regulatory element studied so far but with inconsistent results and no clear association between repeat number and disease risk. Using luciferase reporter constructs in human cell lines here we show that the number of CGG repeats has no strong impact on gene expression, both at mRNA and protein levels. We observed variability in the length of 5'UTR and changes in abundance of the associated transcripts after pathway activation. We show that upstream AUG codons (uAUGs) present only in longer 5'UTRs could negatively regulate the amount of PTC1 isoform L (PTC1-L). The existence of an internal ribosome entry site (IRES) observed using different approaches and mapped in the region comprising the CGG repeats, would counteract the effect of the uAUGs and enable synthesis of PTC1-L under stressful conditions, such as during hypoxia. Higher relative translation efficiency of PTCH1b mRNA in HEK 293T cultured hypoxia was observed by polysomal profiling and Western blot analyses. All our results point to an exceptionally complex and so far unexplored role of 5'UTR PTCH1b cis-element features in the regulation of the Hedgehog-Gli signaling pathway.

Smoothened gene alterations in keratocystic odontogenic tumors

Background

It has been widely demonstrated that the hedgehog pathway is strongly associated with basal cell carcinoma of the skin (NBCCS). To assess potential DNA alterations related to keratocystic odontogenic tumors (KCOTs), we sequenced smoothened (SMO) genes in 12 sporadic KCOTs.

Methods

Polymerase chain reaction (PCR), capillary electrophoresis and dideoxy chain-termination sequencing were used to examine potential DNA alterations in sporadic KCOTs.

Results

Five alterations in SMO genes were detected. Four of these mutations consisted of two synonymous and three missense mutations; two of which have not been reported to date (c.T776A, c.T1281G).

Conclusions

SMO genes may play an important role in the sonic hedgehog (SHH) pathway and could also be responsible for generating KCOTs and NBCCS. However, their influence on SHH signaling remains to be elucidated.