DNA repair mechanisms are essential for tumorigenesis and disruption of HR mechanism is an important predisposing factor of human breast cancers (BC). PALB2 is an important part of the HR. There are similarities between canine mammary tumours (CMT) and BCs. As its human counterpart, PALB2 mutations could be a predisposing factor of CMT.
In this study, we aimed to investigate the impacts of PALB2 variants on tumorigenesis and canine mammary tumor (CMT) malignancy.
We performed Sanger sequencing to detect germline mutations in the WD40 domain of the canine PALB2 gene in CMT patients. We conducted in silico analysis to investigate the variants, and compared the germline PALB2 mutations in humans that cause breast cancer (BC) with the variants detected in dogs with CMT.
We identified an intronic (c.3096+8C>G) variant, two exonic (p.A1050V and p.R1354R) variants, and a 3\' UTR variant (c.4071T>C). Of these, p.R1354R and c.4071T>C novel variants were identified for the first time in this study. We found that the p.A1050V mutation had a significant effect. However, we could not determine sufficient similarity due to the differences in nucleotide/amino acid sequences between two species. Nonetheless, possible variants of human sequences in the exact location as their dog counterparts are associated with several cancer types, implying that the variants could be crucial for tumorigenesis in dogs. Our results did not show any effect of the variants on tumor malignancy.
The current project is the first study investigating the relationship between the PALB2 gene WD40 domain and CMTs. Our findings will contribute to a better understanding of the pathogenic mechanism of the PALB2 gene in CMTs. In humans, variant positions in canines have been linked to cancer-related phenotypes such as familial BC, endometrial tumor, and hereditary cancer predisposition syndrome. The results of bioinformatics analyses should be investigated through functional tests or case-control studies.

BACKGROUND: Cascade screening, defined as helping at-risk relatives get targeted genetic testing of familial variants for dominant hereditary cancer syndromes, is a proven component of cancer prevention; however, its uptake is low. We developed and conducted a pilot study of the ConnectMyVariant intervention, in which participants received support to contact at-risk relatives that extended beyond first-degree relatives and encourage relatives to obtain genetic testing and connect with others having the same variant through email and social media. The support that participants received included listening to participants\' needs, assisting with documentary genealogy to find common ancestors, facilitating direct-to-consumer DNA testing and interpretation, and assisting with database searches.
OBJECTIVE: We aimed to assess intervention feasibility, motivations for participating, and engagement among ConnectMyVariant participants and their families.
METHODS: We used a mixed methods design including both quantitative and qualitative evaluation methods. First, we considered intervention feasibility by characterizing recruitment and retention using multiple recruitment mechanisms, including web-based advertising, dissemination of invitations with positive test results, provider recruitment, snowball sampling, and recruitment through web-based social networks and research studies. Second, we characterized participants\' motivations, concerns, and engagement through project documentation of participant engagement in outreach activities and qualitative analysis of participant communications. We used an inductive qualitative data analysis approach to analyze emails, free-text notes, and other communications generated with participants as part of the ConnectMyVariant intervention.
RESULTS: We identified 84 prospective participants using different recruitment mechanisms; 57 participants were ultimately enrolled in the study for varying lengths of time. With respect to motivations for engaging in the intervention, participants were most interested in activities relating to genealogy and communication with others who had their specific variants. Although there was a desire to find others with the same variant and prevent cancer, more participants expressed an interest in learning about their genealogy and family health history, with prevention in relatives considered a natural side effect of outreach. Concerns about participation included whether relatives would be open to communication, how to go about it, and whether others with a specific variant would be motivated to help find common ancestors. We observed that ConnectMyVariant participants engaged in 6 primary activities to identify and communicate with at-risk relatives: sharing family history, family member testing, direct-to-consumer genealogy genetic testing analysis, contacting (distant) relatives, documentary genealogy, and expanding variant groups or outreach. Participants who connected with others who had the same variant were more likely to engage with several extended family outreach activities.
CONCLUSIONS: This study demonstrated that there is an interest in extended family outreach as a mechanism to improve cascade screening for hereditary cancer prevention. Additional research to systematically evaluate the outcomes of such outreach may be challenging but is warranted.

BACKGROUND: The poly (ADP-ribose) polymerase (PARP) inhibitor olaparib has displayed superior clinical effect in metastatic castration-resistant prostate cancer (mCRPC) patients with the homologous recombination repair (HRR) genes mutations. However, when a patient\'s tumor tissue volume is insufficient for genomic profiling of HRR gene mutations, circulating tumor DNA (ctDNA) may be useful in helping to determine and monitor the efficacy of olaparib, as well as in abiraterone-combination treatment, and for understanding any resistance mechanism related to such mutations.
METHODS: A 61-year-old man who was diagnosed with metastatic prostate adenocarcinoma was initially hormone sensitivity, showing high Gleason score (5 + 5 = 10) and absolute positive rate (14/14 biopsied specimens). Following failure of several standard therapies, the patient progressed to mCRPC. Surprisingly, the patient showed good response to olaparib-abiraterone-prednisone combination treatment (an androgen-deprivation therapy, provided as the \'final choice\' in China). Serum total prostate-specific antigen (TPSA) level reduced and symptoms remitted for 4 months. However, thereafter, serum TPSA levels began slowly increasing, indicating development of olaparib resistance. Subsequent comprehensive genomic profiling of ctDNA, screening 508 cancer-related genes by next-generation sequencing, identified 10 somatic variants as well as 3 copy number alterations. Two identified reverse missense mutations in partner and localizer of BRCA2 (PALB2) may have recovered the reading frame, restoring function of the primary germline PALB2 mutation and causing resistance to the PARP inhibitor olaparib.
CONCLUSIONS: Reverse mutations in PALB2, discovered via genomic profiling of ctDNA, may represent a potential resistance mechanism against olaparib in mCRPC.

During DNA repair, BRCA1 and BRCA2 interact with the tumor suppressor partner and localizer of BRCA2 (PALB2). PALB2 mutations are associated with an increased risk of breast and ovarian carcinoma, and upregulated PALB2 expression is associated with poor clinical outcomes. The present study investigated the role and prognostic value of PALB2 in pancreatic ductal adenocarcinoma (PDAC). PALB2 expression was inhibited using a small interfering RNA in PDAC cell lines, and the subsequent effects on cell proliferation and migration were investigated. Tissue microarrays from 157 patients undergoing a pancreaticoduodenectomy for PDAC were analyzed via immunohistochemistry, and PALB2 expression was compared with patient outcomes using Kaplan-Meier curves and the multivariate Cox regression model. PALB2-knockdown in PDAC cells had little effect on cell proliferation, but significantly decreased cell migration. Relatively high PALB2 expression was observed in PDAC tissues compared with in peritumoral tissues. Overall survival (OS) was negatively associated with PALB2 expression. TNM stage and PALB2 expression were identified as independent prognostic factors associated with OS via multivariate analysis. Overall, the present study demonstrated that PDAC cell migration was dependent on PALB2, which was further supported by the finding that elevated PALB2 expression in PDAC tissues was associated with poor survival in patients with PDAC. Therefore, PALB2 may serve as a novel prognostic marker in PDAC, which may aid with the development of therapeutic strategies for the disease.

PALB2 mutation is associated with increased breast cancer risk; however, PALB2 mutation is rare in sporadic breast cancer cases and little is known about PALB2 expression in breast cancer. Here, we evaluated the prognostic effects of PALB2 with tissue microarray specimens of 117 female breast cancer patients, and determined the potential underlying mechanisms in cell models. In immunohistochemical analysis, we found increased expression of PALB2 in breast cancer tissues compared with the adjacent normal ductal epithelium (P < 0.001). Higher PALB2 scores were positively associated with histological grade and higher PALB2 expression was found in patients that were Her-2 negative compared with those that were positive (P < 0.05). Interestingly, higher expression of PALB2 was significantly associated with poorer overall survival (P < 0.01) in patients with stage III or nearby lymph node metastasis (N1, N2 or N3). In vitro studies found that PALB2 may promote the migration and invasion of MDA-MB-231 cells through E-cadherin suppression and NF-κB activation. In conclusion, these results suggest that PALB2 expression levels may serve as a novel prognostic factor for breast cancer patients.