Conformational Propensity and Biological Studies of Proline Mutated LR Peptides Inhibiting Human Thymidylate Synthase and Ovarian Cancer Cell Growth

[A pedigree study of laryngo-onycho-cutaneous syndrome with a novel mutation on LAMA3 gene]

Objective:To detect genetic mutations in a case of laryngo-onycho-cutaneous syndrome, and to explore the possible molecular biological pathogenic causes. Methods:With informed consent, the family clinical data of the child with laryngo-onycho-cutaneous syndrome were collected, peripheral blood of the protester and his parents was collected and DNA was extracted, and gene detection was performed by high-throughput sequencing method. Sanger sequencing was used to verify and analyze the mutation sites of the probs and their families. Results:Genetic testing of the proband revealed homozygous mutation of LAMA3 gene c.171+1G>A site, which is splicing mutation. There was no report in the literature, which was a new mutation site. The parents of the proband had normal phenotype and heterozygous mutation at this locus was detected. Conclusion:Homozygous mutation of LAMA3 c.171+1G>A is the likely pathogenic of the proband, and this study expands the mutant spectrum of LAMA3. The clinical phenotype of laryngo-onycho-cutaneous syndrome is highly variable, and the multidisciplinary diagnosis and treatment can effectively avoid missed diagnosis and misdiagnosis.

DTYMK promote hepatocellular carcinoma proliferation by regulating cell cycle

Overexpression of DTYMK is related with tumorigenesis and progression in several human tumors. However, the role of upregulated DTYMK in hepatocellular carcinoma (HCC) patients still remains unclear. In this study, the DTYMK expression in HCC tumors was evaluated in three GEO series (GSE14520, GSE54236, GSE63898), TCGA-LIHC, and ICGC-IRLR-JP cohorts. Survival analysis of DTYMK based on TCGA-LIHC and ICGC-LIRI-JP cohorts was conducted. We found that DTYMK was dramatically upregulated in tumor tissue compared with that in adjacent liver tissue. Kaplan-Meier analysis revealed that high expression of DTYMK in HCC patients' tumor tissue was significantly corresponded to worse overall survival (OS) (P < 0.05). Further analysis showed that overexpressing DTYMK led to poor relapse free survival (RFS) and disease-specific survival (DSS) (all P < 0.05). In conclusion, DTYMK is upregulated in tumors and correlated with poor prognosis in HCC patients. In our report, DTYMK is higher expression in HCC cancer tissue and cell line than tumor adjacent tissue and normal liver cell line. Knocking down DTYMK can inhabit tumor cell proliferation by interfering cell cycle, whereas overexpression of DTYMK can promote tumor cell proliferation. These findings indicate that upregulation of DTYMK enhances tumor growth and proliferation by promoting cell cycle.

Folic Acid-Peptide Conjugates Combine Selective Cancer Cell Internalization with Thymidylate Synthase Dimer Interface Targeting

Drug-target interaction, cellular internalization, and target engagement should be addressed to design a lead with high chances of success in further optimization stages. Accordingly, we have designed conjugates of folic acid with anticancer peptides able to bind human thymidylate synthase (hTS) and enter cancer cells through folate receptor α (FRα) highly expressed by several cancer cells. Mechanistic analyses and molecular modeling simulations have shown that these conjugates bind the hTS monomer-monomer interface with affinities over 20 times larger than the enzyme active site. When tested on several cancer cell models, these conjugates exhibited FRα selectivity at nanomolar concentrations. A similar selectivity was observed when the conjugates were delivered in synergistic or additive combinations with anticancer agents. At variance with 5-fluorouracil and other anticancer drugs that target the hTS catalytic pocket, these conjugates do not induce overexpression of this protein and can thus help combating drug resistance associated with high hTS levels.

Cyclic Peptides Acting as Allosteric Inhibitors of Human Thymidylate Synthase and Cancer Cell Growth

Thymidylate synthase (TS) is a prominent drug target for different cancer types. However, the prolonged use of its classical inhibitors, substrate analogs that bind at the active site, leads to TS overexpression and drug resistance in the clinic. In the effort to identify anti-TS drugs with new modes of action and able to overcome platinum drug resistance in ovarian cancer, octapeptides with a new allosteric inhibition mechanism were identified as cancer cell growth inhibitors that do not cause TS overexpression. To improve the biological properties, 10 cyclic peptides (cPs) were designed from the lead peptides and synthesized. The cPs were screened for the ability to inhibit recombinant human thymidylate synthase (hTS), and peptide 7 was found to act as an allosteric inhibitor more potent than its parent open-chain peptide [Pro³]LR. In cytotoxicity studies on three human ovarian cancer cell lines, IGROV-1, A2780, and A2780/CP, peptide 5 and two other cPs, including 7, showed IC₅₀ values comparable with those of the reference drug 5-fluorouracil, of the open-chain peptide [d-Gln⁴]LR, and of another seven prolyl derivatives of the lead peptide LR. These promising results indicate cP 7 as a possible lead compound to be chemically modified with the aim of improving both allosteric TS inhibitory activity and anticancer effectiveness.

Correlation of LAMA3 with onset and prognosis of ovarian cancer

Correlation of laminin subunit α3 (LAMA3) gene with onset and prognosis of ovarian cancer was investigated. In total, 210 ovarian cancer patients who received surgical resection in West China Second Hospital from March 2011 to March 2013 were randomly selected, and another 160 non-ovarian cancer patients who needed ovariectomy were also selected. The relative expression of LAMA3 gene was compared via quantitative polymerase chain reaction (qPCR) in carcinoma tissues, para-carcinoma tissues and non-carcinoma normal tissues in ovarian cancer patients. The methylation level was compared among the above three tissue types. The correlation between the mutation site rs12373237 in LAMA3 gene and onset was analyzed. The expression of laminin in ovarian cancer was detected using immunohistochemistry. Moreover, the 5-year survival rate after operation was recorded and the survival curve was plotted. The expression level of LAMA3 was lower in carcinoma tissues than those in normal tissues and para-carcinoma tissues (P<0.05). The methylation degree was lower in para-carcinoma tissues and normal tissues than that in carcinoma tissues (P<0.05). The CC homozygous mutation of rs12373237 was highly correlated with the onset of ovarian cancer (OR=4.333, P=0.028). The expression of LAMA3 was classified via immunohistochemistry, and the number in high-expression group (63.8%) was larger than that in low-expression group (36.2%) (P<0.05). According to the analysis of 5-year survival rate, the recurrence-free survival rate and overall survival rate in LAMA3 high-expression group were significantly higher than those in LAMA3 low-expression group (P<0.05). The expression level and base mutation of LAMA3 gene can change the level of laminin, which have a certain influence on the onset and prognosis of ovarian cancer.