Anti-PPP1R12A monoclonal antibody, clone ZF447

Aim. To investigate the correlation between PPP1R12A gene copy number and clinical outcomes of oxaliplatin-based regimen in stage III colorectal cancer (CRC). Methods. A total of 139 paraffin-embedded tissue samples of stage III CRC patients who received oxaliplatin-based treatment after radical surgery were recruited. Genomic DNA was extracted and purified from paraffin-embedded sections. Quantitative PCR methods were used to detect the relative copy number (RCN) of PPP1R12A. Results. Statistical analysis demonstrated that low PPP1R12A RCN was associated with poor RFS (HR = 2.186, 95% CI: 1.293-3.696; p = 0.003) and OS (HR = 2.782, 95% CI: 1.531-5.052; p < 0.001). Additionally, when patients were stratified according to subgroups of stage III and tumor location, poor RFS and OS were also observed in the low PPP1R12A RCN group with significance (RFS: IIIB HR = 2.870, p < 0.001; colon HR = 1.910, p = 0.037; OS: IIIB HR = 3.527, p < 0.001; IIIC HR = 2.662, p = 0.049; rectum HR = 4.229, p = 0.002). Conclusion. Our findings suggest the copy number of PPP1R12A can independently predict recurrence and overall survival of stage III colorectal cancer patients receiving oxaliplatin-based chemotherapy.

Background Ovarian cancer is one of the most common and malignant cancers, partly due to its late diagnosis and high recurrence. Chemotherapy resistance has been linked to poor prognosis and is believed to be linked to the cancer stem cell (CSC) pool. Therefore, elucidating the molecular mechanisms mediating therapy resistance is essential to finding new targets for therapy-resistant tumors. Methods shRNA depletion of MYPT1 in ovarian cancer cell lines, miRNA overexpression, RT-qPCR analysis, patient tumor samples, cell line- and tumorsphere-derived xenografts, in vitro and in vivo treatments, analysis of data from ovarian tumors in public transcriptomic patient databases and in-house patient cohorts. Results We show that MYPT1 (PPP1R12A), encoding myosin phosphatase target subunit 1, is downregulated in ovarian tumors, leading to reduced survival and increased tumorigenesis, as well as resistance to platinum-based therapy. Similarly, overexpression of miR-30b targeting MYPT1 results in enhanced CSC-like properties in ovarian tumor cells and is connected to the activation of the Hippo pathway. Inhibition of the Hippo pathway transcriptional co-activator YAP suppresses the resistance to platinum-based therapy induced by either low MYPT1 expression or miR-30b overexpression, both in vitro and in vivo. Conclusions Our work provides a functional link between the resistance to chemotherapy in ovarian tumors and the increase in the CSC pool that results from the activation of the Hippo pathway target genes upon MYPT1 downregulation. Combination therapy with cisplatin and YAP inhibitors suppresses MYPT1-induced resistance, demonstrating the possibility of using this treatment in patients with low MYPT1 expression, who are likely to be resistant to platinum-based therapy.