Detection of somatic mutations and germline polymorphisms in mitochondrial DNA of uterine fibroids patients

Roles of MT-ND1 in Cancer

The energy shift toward glycolysis is one of the hallmarks of cancer. Complex I is a vital enzyme complex necessary for oxidative phosphorylation. The mitochondrially encoded NADH: ubiquinone oxidoreductase core subunit 1 (MT-ND1) is the largest subunit coded by mitochondria of complex I. The present study summarizes the structure and biological function of MT-ND1. From databases and literature, the expressions and mutations of MT-ND1 in a variety of cancers have been reviewed. MT-ND1 may be a biomarker for cancer diagnosis and prognosis. It is also a potential target for cancer therapy.

A View on Uterine Leiomyoma Genesis through the Prism of Genetic, Epigenetic and Cellular Heterogeneity

Uterine leiomyomas (ULs), frequent benign tumours of the female reproductive tract, are associated with a range of symptoms and significant morbidity. Despite extensive research, there is no consensus on essential points of UL initiation and development. The main reason for this is a pronounced inter- and intratumoral heterogeneity resulting from diverse and complicated mechanisms underlying UL pathobiology. In this review, we comprehensively analyse risk and protective factors for UL development, UL cellular composition, hormonal and paracrine signalling, epigenetic regulation and genetic abnormalities. We conclude the need to carefully update the concept of UL genesis in light of the current data. Staying within the framework of the existing hypotheses, we introduce a possible timeline for UL development and the associated key events—from potential prerequisites to the beginning of UL formation and the onset of driver and passenger changes.

Long-term use of ultra-low-dose mifepristone for uterine leiomyoma control and safety discussion: A case report

RATIONALE

In recent years, many clinical trials have used low-dose mifepristone to control uterine fibroids, some of which have achieved good results. However, according to the classic concept, long-term use of mifepristone could induce malignant transformation of the endometrium, and the effect of ultra-low-dose of mifepristone on uterine fibroids is still uncertain. Researchers are short on cases of uterine fibroids treated with mifepristone for long periods (more than a year).

PATIENT CONCERNS

A 47-year-old woman went to the hospital because of anemia.

DIAGNOSES

The patient was diagnosed with uterine leiomyoma.

INTERVENTIONS

The patient refused the suggestion of surgery, she was continuously treated with an ultra-low-dose (12.5 mg per 5 days) of mifepristone monotherapy for 4 years.

OUTCOMES

The uterine leiomyoma was stable, anemia and other symptoms disappeared, and the menstrual cycle, liver and kidney function, and tumor markers were normal.

LESSONS

Judging from our case, long-term, ultra-low-dose mifepristone for uterine fibroids treatment was safe and more effective than conventional therapy.

Multiple Mutations in Exon-2 of Med-12 Identified in Uterine Leiomyomata

Background:

Uterine leiomyomata (UL), commonly known as uterine fibroids, are benign smooth muscle tumors of the myometrium. They cause pelvic pain, abnormal uterine bleeding, and infertility in women of reproductive age. The ovarian hormone estrogen is the main stimulator for the fibroid growth. The etiology is not yet clearly understood; however, UL are believed to be monoclonal tumors arising from a common progenitor cell. Chromosomal cytogenetic abnormalities have been demonstrated in 40–50% of the fibroids. The most frequent tumor specific genetic alterations in UL were identified in exon-2 of Mediator Complex Subunit 12 (MED-12).

Methods:

In the present study, twenty-two multiple fibroids were evaluated both from the same uterus and from different uteri, of four women, for somatic mutations in hotspot region of MED-12. The tissue DNA of the UL’s was isolated, amplified by PCR visualized on gel and sent for Sanger sequencing.

Results:

The results indicate several variants in exon-2 and flanking intronic regions, seven exonic variants and five intronic variants which provide evidence that multiple UL in the same uterus may not be clonal in origin.

Conclusion:

This study indicates genetic heterogeneity. UL may not have a clonal origin, these exon-2 variants of MED-12 gene could be involved in UL progression.

Molecular and Cellular Insights into the Development of Uterine Fibroids

Uterine leiomyomas represent the most common benign gynecologic tumor. These hormone-dependent smooth-muscle formations occur with an estimated prevalence of ~70% among women of reproductive age and cause symptoms including pain, abnormal uterine bleeding, infertility, and recurrent abortion. Despite the prevalence and public health impact of uterine leiomyomas, available treatments remain limited. Among the potential causes of leiomyomas, early hormonal exposure during periods of development may result in developmental reprogramming via epigenetic changes that persist in adulthood, leading to disease onset or progression. Recent developments in unbiased high-throughput sequencing technology enable powerful approaches to detect driver mutations, yielding new insights into the genomic instability of leiomyomas. Current data also suggest that each leiomyoma originates from the clonal expansion of a single transformed somatic stem cell of the myometrium. In this review, we propose an integrated cellular and molecular view of the origins of leiomyomas, as well as paradigm-shifting studies that will lead to better understanding and the future development of non-surgical treatments for these highly frequent tumors.

Expanded Somatic Mutation Spectrum of MED12 Gene in Uterine Leiomyomas of Saudi Arabian Women

MED12, a subunit of mediator complex genes is known to harbor genetic mutations, (mostly in exon 2), causal to the genesis of uterine leiomyomas among Caucasian, African American, and Asian women. However, the precise relationship between genetic mutations vs. protein or disease phenotype is not well-explained. Therefore, we sought to replicate the MED12 mutation frequency in leiomyomas of Saudi Arabian women, who represents ethnically and culturally distinct population. We performed molecular screening of MED12 gene (in 308 chromosomes belonging to 154 uterine biopsies), analyzed the genotype-disease phenotype correlations and determined the biophysical characteristics of mutated protein through diverse computational approaches. We discovered that >44% (34/77) leiomyomas of Arab women carry a spectrum of MED12 mutations (30 missense, 1 splice site, and 3 indels). In addition to known codon 44, we observed novel somatic mutations in codons 36, 38, and 55. Most genetically mutated tumors (27/30; 90%) demonstrated only one type of genetic change, highlighting that even single allele change in MED12 can have profound impact in transforming the normal uterine myometrium to leiomyomas. An interesting inverse correlation between tumor size and LH is observed when tumor is positive to MED12 mutation (p < 0.05). Our computational investigations suggest that amino acid substitution mutations in exon-2 region of MED12 might contribute to potential alterations in phenotype as well as the stability of MED12 protein. Our study, being the first one from Arab world, confirms the previous findings that somatic MED12 mutations are critical to development and progression of uterine leiomyomas irrespective of the ethnic background. We recommend that mutation screening, particularly codon 44 of MED12 can assist in molecular diagnostics of uterine leiomyomas in majority of the patients.

Analysis to Estimate Genetic Variations in the Idarubicin-Resistant Derivative MOLT-3

Gene alterations are a well-established mechanism leading to drug resistance in acute leukemia cells. A full understanding of the mechanisms of drug resistance in these cells will facilitate more effective chemotherapy. In this study, we investigated the mechanism(s) of drug resistance in the human acute leukemia cell line MOLT-3 and its idarubicin-resistant derivative MOLT-3/IDR through complete mitochondrial and nuclear DNA analyses. We identified genetic differences between these two cell lines. The ND3 mutation site (p.Thr61Ile) in the mitochondrial DNA sequence was unique to MOLT-3/IDR cells. Moreover, we identified five candidate genes harboring genetic alterations, including GALNT2, via CGH array analysis. Sequencing of the GALNT2 exon revealed a G1716K mutation present within the stop codon in MOLT-3/IDR cells but absent from MOLT-3 cells. This mutation led to an additional 18 amino acids in the protein encoded by GALNT2. Using real-time PCR, we determined an expression value for this gene of 0.35. Protein structure predictions confirmed a structural change in GALNT2 in MOLT-3/IDR cells that corresponded to the site of the mutation. We speculate that this mutation may be related to idarubicin resistance.

Mitochondrial haplogroups and polymorphisms reveal no association with sporadic prostate cancer in a southern European population

BACKGROUND

It is known that mitochondria play an important role in certain cancers (prostate, renal, breast, or colorectal) and coronary disease. These organelles play an essential role in apoptosis and the production of reactive oxygen species; in addition, mtDNA also reveals the history of populations and ancient human migration. All these events and variations in the mitochondrial genome are thought to cause some cancers, including prostate cancer, and also help us to group individuals into common origin groups. The aim of the present study is to analyze the different haplogroups and variations in the sequence in the mitochondrial genome of a southern European population consisting of subjects affected (n = 239) and non-affected (n = 150) by sporadic prostate cancer.

METHODOLOGY AND PRINCIPAL FINDINGS

Using primer extension analysis and DNA sequencing, we identified the nine major European haplogroups and CR polymorphisms. The frequencies of the haplogroups did not differ between patients and control cohorts, whereas the CR polymorphism T16356C was significantly higher in patients with PC compared to the controls (p = 0.029). PSA, staging, and Gleason score were associated with none of the nine major European haplogroups. The CR polymorphisms G16129A (p = 0.007) and T16224C (p = 0.022) were significantly associated with Gleason score, whereas T16311C (p = 0.046) was linked with T-stage.

CONCLUSIONS AND SIGNIFICANCE

Our results do not suggest that mtDNA haplogroups could be involved in sporadic prostate cancer etiology and pathogenesis as previous studies performed in middle Europe population. Although some significant associations have been obtained in studying CR polymorphisms, further studies should be performed to validate these results.

No evidence for the role of somatic mutations and promoter hypermethylation of FH gene in the tumorigenesis of nonsyndromic uterine leiomyomas

Fumarate hydratase (FH) gene is reported to have specific involvement in syndromic uterine tumors, but its role in nonsyndromic forms is still unclear. Hence, the present study has aimed to screen the role of promoter methylation status and mutations in exon 2 and 7 regions of FH gene in the genesis of nonsyndromic uterine leiomyomas. Leiomyoma and myometrium tissues were collected from 85 hysterectomized uterine specimens. DNA from each of the biopsy was subjected to PCR, methylation-specific restriction assay, and DNA sequencing. In silico analysis was carried out to identify the impact of sequence variants on the protein structure. Chi-square (χ (2)) test was used to compare the promoter methylation proportions of leiomyoma and myometrium tissues. No sequence variants were observed in exon 2 region, but three novel heterozygous germ line sequence variants, i.e., c.1010A > C, c.1021 G > A, and c.1066 T > C in exon 7 region of the FH gene were detected in 14/85 (16.5 %) of the cases examined. In silico analysis results showed that c.1010A > C and c.1021 G > A mutations damage the structure and function of FH, whereas c.1066 T > C mutation is mostly tolerant or neutral. No significant difference of FH promoter methylation status between the leiomyoma (11.76 %) and myometrium (5.88 %) tissues was observed (P = 0.176). Therefore, it is concluded that somatic mutations in FH do not show pronounced effect in nonsyndromic uterine leiomyomas compared to that of their syndromic counterparts. However, higher frequency of FH mutations in leiomyoma cases raises the need to conduct larger number of prospective case-control and family-based studies to assess them as risk markers to nonsyndromic leiomyomas.