PMS2 germline mutation c.943C>T (p.Arg315*)-induced Lynch syndrome-associated ovarian cancer

DNA Repair and Ovarian Carcinogenesis: Impact on Risk, Prognosis and Therapy Outcome

There is ample evidence for the essential involvement of DNA repair and DNA damage response in the onset of solid malignancies, including ovarian cancer. Indeed, high-penetrance germline mutations in DNA repair genes are important players in familial cancers: BRCA1, BRCA2 mutations or mismatch repair, and polymerase deficiency in colorectal, breast, and ovarian cancers. Recently, some molecular hallmarks (e.g., TP53, KRAS, BRAF, RAD51C/D or PTEN mutations) of ovarian carcinomas were identified. The manuscript overviews the role of DNA repair machinery in ovarian cancer, its risk, prognosis, and therapy outcome. We have attempted to expose molecular hallmarks of ovarian cancer with a focus on DNA repair system and scrutinized genetic, epigenetic, functional, and protein alterations in individual DNA repair pathways (homologous recombination, non-homologous end-joining, DNA mismatch repair, base- and nucleotide-excision repair, and direct repair). We suggest that lack of knowledge particularly in non-homologous end joining repair pathway and the interplay between DNA repair pathways needs to be confronted. The most important genes of the DNA repair system are emphasized and their targeting in ovarian cancer will deserve further attention. The function of those genes, as well as the functional status of the entire DNA repair pathways, should be investigated in detail in the near future.

PMS2 germline mutation c.943C>T (p.Arg315*)-induced Lynch syndrome-associated ovarian cancer

Background

Lynch syndrome (LS) is an autosomal dominant cancer predisposition condition caused by germline heterozygous mutations in mismatch repair (MMR) genes. However, as one of the MMR genes, PMS2 mutation‐induced LS‐associated ovarian cancer (LSAOC) has rarely been reported.

Methods

Next‐generation sequencing (NGS) or Sanger sequencing was used to detect the genetic status of one family including four generations with 16 members. Then, quantitative real‐time PCR (qPCR), western blotting, immunohistochemistry (IHC) staining, and Swiss‐Model software were used to identify the function of the PMS2 mutation.

Results

Five individuals [I‐1, II‐1, II‐2, II‐4, and III‐2 (proband)] suffered from LS‐associated cancers, for example, colon cancer, gastric cancer, and ovarian cancer, with the age of onset ranging from 39 to 70 years old. A PMS2 germline heterozygous mutation (c.943C>T) was confirmed in three members [II‐9, III‐2, and IV‐1] by gene sequencing. In addition, this PMS2 mutation was verified by qPCR, western blotting, and IHC, and a dramatic change with partial loss of the C‐terminal domain in an α‐helix might be exhibited.

Conclusion

Carrying PMS2 germline mutations (c.943C>T) confers an extremely high susceptibility of suffering from LS‐associated cancers. Thus, close clinical monitoring and prophylactic surgery is highly recommended to help reduce the morbidity and mortality of LS‐associated cancers.