RESUMO
Cytokeratin 19 (CK19) is a complex intracytoplasmic cytoskeletal protein primarily localized in the ducts of the mammary gland and skin epithelial cells. In humans, the expression of CK19 gene within circulating tumor cells (CTCs) extracted from blood samples of breast cancer patients reflects tumor cell activity, offering valuable insights for predicting early metastatic relapse or monitoring treatment effectiveness. However, knowledge of serum tumor markers is limited in veterinary oncology. Recently, droplet digital PCR (ddPCR), has been employed to explore rare target genes due to its heightened sensitivity and accuracy as a novel molecular diagnostic tool. The objectives of this study were to investigate the expression of the CK19 mRNA in CTCs, non-neoplastic mammary tissues, and both benign and malignant canine mammary tumors (CMTs) through ddPCR analysis. In Study I, we optimized the discard volume for blood samples to reduce CK19 contamination from skin epithelial cells post-venipuncture. The results revealed that discarding the initial 3 mL of blood was adequate and effective in eliminating CK19 mRNA contamination. In Study II, after the removal of the initial 3 mL of blood, we investigated CK19 mRNA-positive CTCs in the peripheral blood of normal healthy dogs, including those with benign and malignant CMTs. Intriguingly, CK19 mRNA was undetectable in all blood samples. The expression of CK19 mRNA in mammary tissues was investigated in Study III. The copy number (CN) ratios of the CK19 gene in non-neoplastic mammary tissues (14.77 ± 14.65) were significantly higher (P < 0.05) than those in benign (4.23 ± 3.35) and malignant groups (6.56 ± 5.64). Notably, no difference was observed between the benign and malignant groups. In conclusion, CK19 mRNA appeared unlikely to be a suitable candidate as a biomarker in the peripheral blood of CMTs, while the CN ratio in mammary tissues could serve as a potential discriminator between non-neoplastic and CMT groups, complementing the gold standard of histopathological examination.
Assuntos
Neoplasias da Mama , Doenças do Cão , Neoplasias Mamárias Animais , Humanos , Cães , Animais , Feminino , Queratina-19/genética , Queratina-19/metabolismo , Neoplasias Mamárias Animais/diagnóstico , Neoplasias Mamárias Animais/genética , Neoplasias Mamárias Animais/metabolismo , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Neoplasias da Mama/veterinária , Reação em Cadeia da Polimerase/veterinária , Biomarcadores Tumorais/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Doenças do Cão/diagnóstico , Doenças do Cão/genética , Doenças do Cão/metabolismoRESUMO
In humans, peripheral blood cytokeratin 19 (CK19) mRNA-positive circulating tumor cells (CTCs) was utilized to identify early-stage breast cancer patients with micrometastatic disease who are at risk for disease progression and monitor treatment response in patients with advanced disease. To our knowledge, there has been little research regarding CK19 in canine mammary tumors (CMTs) using molecular methods. A droplet digital PCR (ddPCR) is proposed as a precise and sensitive quantification of nucleic acid targets. Hence, this study aimed to validate a newly designed assay for CK19 detection in canine blood and mammary tissue, along with the reference gene HPRT, by ddPCR. All primers and probes showed a precise match with the exon region of target genes. The assay exhibited PCR efficacy of 90.4% and 91.0% for CK19 and HPRT amplifications with linearity, respectively. The annealing temperature (Ta) for duplex ddPCR was 55 °C, providing the highest concentrations of both genes tested by the synthetic plasmid DNA. The limit of detection (LOD) of CK19 and HPRT were 2.16 ± 1.27 and 2.44 ± 1.31 copies/µL, respectively. Finally, the ddPCR assay was validated with canine peripheral blood, non-neoplastic mammary tissues and spiked samples. Our findings provide a new platform for CK19 studies in CMT diagnosis through blood and mammary tissues.
Assuntos
Queratina-19 , Glândulas Mamárias Humanas , Animais , Cães , Humanos , Hipoxantina Fosforribosiltransferase , Queratina-19/genética , Reação em Cadeia da Polimerase/métodos , RNA Mensageiro/genéticaRESUMO
Circulating cell-free DNA (cfDNA) has attracted attention as a non-invasive biomarker for diagnosing and monitoring various cancers. Given that human papillomavirus (HPV) DNA integration and overexpression of E6/E7 oncogenes are pivotal events for carcinogenesis, we sought to determine if HPV E7 cfDNA could serve as a specific biomarker for cervical cancer detection. We applied droplet digital PCR (ddPCR) to quantify HPV16/18 E7 cfDNA from the serum of patients with cervical cancer, cervical intraepithelial neoplasia, and controls. HPV16/18 E7 cfDNA was highly specific for cervical cancer, displaying 30.77% sensitivity, 100% specificity, and an area under the curve of 0.65. Furthermore, we developed a sensitive isothermal detection of HPV16/18 E7 and the PIK3CA WT reference gene based on recombinase polymerase amplification combined with a lateral flow strip (RPA-LF). The assay took less than 30 min and the detection limit was 5-10 copies. RPA-LF exhibited 100% sensitivity and 88.24% specificity towards HPV16/18 E7 cfDNA in clinical samples. The agreement between RPA-LF and ddPCR was 83.33% (κ = 0.67) for HPV16 E7 and 100% (κ = 1.0) for HPV18 E7, indicating a good correlation between both tests. Therefore, we conclude that HPV E7 cfDNA represents a potential tumor marker with excellent specificity and moderate sensitivity for minimally invasive cervical cancer monitoring. Moreover, the RPA-LF assay provides an affordable, rapid, and ultrasensitive tool for detecting HPV cfDNA in resource-limited settings.
Assuntos
Biomarcadores Tumorais/genética , Ácidos Nucleicos Livres/sangue , Ácidos Nucleicos Livres/genética , DNA Viral/genética , Proteínas de Ligação a DNA/sangue , Proteínas Oncogênicas Virais/sangue , Papillomaviridae/genética , Proteínas E7 de Papillomavirus/sangue , Neoplasias do Colo do Útero/virologia , Adulto , Estudos de Casos e Controles , Classe I de Fosfatidilinositol 3-Quinases/genética , DNA Viral/sangue , Proteínas de Ligação a DNA/genética , Feminino , Humanos , Pessoa de Meia-Idade , Proteínas Oncogênicas Virais/genética , Proteínas E7 de Papillomavirus/genética , Reação em Cadeia da Polimerase , Curva ROC , Neoplasias do Colo do Útero/diagnósticoRESUMO
Circulating lncRNAs have attracted considerable attention as potential noninvasive biomarkers for diagnosing cancers. RT-qPCR is the canonical technique for detecting circulating RNA and depends largely on stable reference genes for data normalization. However, no systematic evaluation of reference genes for serum lncRNA has been reported for cervical cancer. Here, we profiled and validated lncRNA expression from serum of cervical cancer patients and controls using microarrays and RT-qPCR. We identified lncRNA RP11-204K16.1, XLOC_012542, and U6 small nuclear RNA as the most stable reference genes based on geNorm, NormFinder, BestKeeper, delta Ct, and RefFinder. These genes were suitable also for samples from different age groups or with hemolysis. Additionally, we discovered lncRNA AC017078.1 and XLOC_011152 as candidate biomarkers, whose expression was down-regulated in cervical cancer. Our findings could aid research on circulating lncRNA and the discovery of blood-based biomarkers for cervical cancer diagnosis.