PPFIA1-targeting miR-181a mimic and saRNA overcome imatinib resistance in BCR-ABL1-independent chronic myeloid leukemia by suppressing leukemia stem cell regeneration

A large proportion of patients with chronic myeloid leukemia (CML; 20%-50%) develop resistance to imatinib in a BCR-ABL1-independent manner. Therefore, new therapeutic strategies for use in this subset of imatinib-resistant CML patients are urgently needed. In this study, we used a multi-omics approach to show that PPFIA1 was targeted by miR-181a. We demonstrate that both miR-181a and PPFIA1-siRNA reduced the cell viability and proliferative capacity of CML cells in vitro, as well as prolonged the survival of B-NDG mice harboring human BCR-ABL1-independent imatinib-resistant CML cells. Furthermore, treatment with miR-181a mimic and PPFIA1-siRNA inhibited the self-renewal of c-kit⁺ and CD34⁺ leukemic stem cells and promoted their apoptosis. Small activating (sa)RNAs targeting the promoter of miR-181a increased the expression of endogenous primitive miR-181a (pri-miR-181a). Transfection with saRNA 1-3 inhibited the proliferation of imatinib-sensitive and -resistant CML cells. However, only saRNA-3 showed a stronger and more sustained inhibitory effect than the miR-181a mimic. Collectively, these results show that miR-181a and PPFIA1-siRNA may overcome the imatinib resistance of BCR-ABL1-independent CML, partially by inhibiting the self-renewal of leukemia stem cells and promoting their apoptosis. Moreover, exogenous saRNAs represent promising therapeutic agents in the treatment of imatinib-resistant BCR-ABL1-independent CML.

High expression of PPFIA1 in human esophageal squamous cell carcinoma correlates with tumor metastasis and poor prognosis

BACKGROUND

PTPRF interacting protein alpha 1 (PPFIA1) is reportedly related to the occurrence and progression of several kinds of malignancies. However, its role in esophageal squamous cell carcinoma (ESCC) is unclear. This current study investigated the prognostic significance and biological functions of PPFIA1 in ESCC.

METHODS

Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), and Gene Expression Omnibus (GEO) were used to investigate PPFIA1 expression in esophageal cancer. The relationship between PPFIA1 expression and clinicopathological characteristics and patient survival was evaluated in GSE53625 dataset, and verified in the cDNA array based on qRT-PCR and tissue microarray (TMA) dataset based on immunohistochemistry. The impact of PPFIA1 on the migration and invasion of cancer cells were investigated by wound-healing and transwell assays, respectively.

RESULTS

The expression of PPFIA1 was obviously increased in ESCC tissues versus adjacent esophageal tissues according to online database analyses (all P < 0.05). High PPFIA1 expression was closely related to several clinicopathological characteristics, including tumor location, histological grade, tumor invasion depth, lymph node metastasis, and tumor-node-metastasis (TNM) stage. High PPFIA1 expression was related to worse outcomes and was identified as an independent prognostic factor of overall survival in ESCC patients (GSE53625 dataset, P = 0.019; cDNA array dataset, P < 0.001; TMA dataset, P = 0.039). Downregulation of PPFIA1 expression can significantly reduce the migration and invasion ability of ESCC cells.

CONCLUSION

PPFIA1 is related to the migration and invasion of ESCC cells, and can be used as a potential biomarker to evaluate the prognosis of ESCC patients.

High PPFIA1 expression promotes cancer survival by suppressing CD8+ T cells in breast cancer: drug discovery and machine learning approach

BACKGROUND

PTPRF-interacting protein alpha 1 (PPFIA1) plays an important role as a regulator of cell motility and tumor cell invasion and is frequently amplified in breast cancer. The aim of this study was to investigate the clinicopathologic features, survival, anticancer immunities and specific gene sets related to high PPFIA1 expression in patients with breast cancer. We verified the importance of PPFIA1 and survival rates using machine learning and identified drugs that can effectively reduce breast cancer cells with high PPFIA1 expression.

METHODS

This study analyzed clinicopathologic factors, survival rates, immune profiles and gene sets according to PPFIA1 expression in 3457 patients with breast cancer from the Kangbuk Samsung Medical Center cohort (456 cases), Molecular Taxonomy of Breast Cancer International Consortium (1904 cases) and The Cancer Genome Atlas (1097 cases). We applied gene set enrichment analysis (GSEA), in silico cytometry, pathway network analyses, in vitro drug screening, and gradient boosting machine (GBM) analysis.

RESULTS

High PPFIA1 expression in breast cancer was associated with worse prognosis, with reduced tumor-infiltrating lymphocytes, especially CD8+ T cells, and increased PD-L1 expression. In pathway network analysis, PPFIA1 was linked directly to the tyrosine-protein phosphatase pathway and indirectly to immune pathways. The importance of PPFIA1's association with survival in GBM analysis was higher than that of perineural and lymphovascular invasion. In in vitro drug screening, expression of PPFIA1 on mRNA level positively correlated with sensitivity of cell lines to erlotinib.

CONCLUSION

High PPFIA1 in patients with breast cancer is related to poor prognosis and decreased anticancer immune response, and erlotinib may be promising for development of therapeutic approaches in patients with tumors overexpressing PPFIA1.

circ_0080145 Enhances Imatinib Resistance of Chronic Myeloid Leukemia by Regulating miR-326/PPFIA1 Axis

Background: Acquired multidrug resistance is often blamed for the failure of chemotherapy in patients with malignant tumors, including chronic myeloid leukemia (CML). In this study, the authors investigated the role of circular RNA 0080145 (circ_0080145) in imatinib (IM) resistance of CML. Materials and Methods: Quantitative real-time polymerase chain reaction was applied to measure the expression of circ_0080145, microRNA-326 (miR-326), and PTPRF interacting protein alpha 1 (PPFIA1) mRNA. 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to determine the half maximal inhibitory concentration (IC50) of IM and cell proliferation. Flow cytometry analysis was utilized to assess cell apoptosis. The levels of glucose uptake and lactate production were examined using specific kits. Protein levels were detected through western blot assay. The targeting relationship between miR-326 and circ_0080145 or PPFIA1 was verified by dual-luciferase reporter assay. The murine xenograft model was constructed to investigate the effect of circ_0080145 in vivo. Results: circ_0080145 was upregulated in IM-resistant CML patients and cells. circ_0080145 silencing suppressed IM resistance, cell growth, and glycolysis and induced apoptosis in IM-resistant CML cells in vitro. Moreover, circ_0080145 knockdown blocked tumor growth and IM resistance in vivo. miR-326 was a target of circ_0080145, and miR-326 inhibition restored the effects of circ_0080145 silencing on cell progression and IM resistance. In addition, PPFIA1 was a target gene of miR-326. The suppressive roles in IM resistance, cell growth and glycolysis, and the promotional role in apoptosis mediated by miR-326 were abolished by PPFIA1 overexpression in IM-resistant CML cells. Conclusion: circ_0080145 contributes to IM resistance via modulating miR-326/PPFIA1 axis, which might provide a novel avenue for CML therapy.

PPFIA1 expression associates with poor response to endocrine treatment in luminal breast cancer

BACKGROUND

PPFIA1 is an important regulator of cell migration and invasion, regulating focal adhesion signalling and disassembly. PPFIA1 is frequently amplified in breast cancer, and recent functional studies indicate that PPFIA1 is an important promoter of migration and invasion in breast cancer. This study aims to evaluate the utility of PPFIA1 expression in the luminal breast cancer as a prognostic marker to predict the response to endocrine therapy.

METHODS

Large, well-characterised cohorts of primary luminal breast cancer patients with long-term follow-up was assessed for the clinical impact of PPFIA1 expression at the transcriptomic and proteomic levels. Prognostic significance of PPFIA1 and its relationship with clinical outcome and benefit of endocrine therapy were analysed. In addition, its association with other related-genes was analysed.

RESULTS

There was significant association between PPFIA1 expression and a member of the liprin family that involves in cell invasion (PPFIBPI), and the cell cycle regulator (CCND1), whereas a negative association was observed with the tumour suppressor gene (CD82). Patients with high PPFIA1 expression were associated with high risk of recurrence, distant metastasis and death from breast cancer (P < 0.05). Importantly, high PPFIA1 expression predicted relapse in a subset of patients who were subject to endocrine treatment alone, and was an independent prognostic marker of unfavourable outcome in these patients (P < 0.05).

CONCLUSIONS

These findings support the proposed role for PPFIA1 as a regulator of cell migration in breast cancer and provides definitive evidence for the clinical utility of PPFIA1 expression in patients with luminal breast cancer. Most importantly, our data suggests that PPFIA1 might be a potential predictive marker for poor benefit from endocrine therapy.

Combined expression and prognostic significance of PPFIA1 and ALG3 in head and neck squamous cell carcinoma

PPFIA family members and ALG3 play important roles in tumorigenesis and tumor progression. However, the exact roles of distinct PPFIA family members and ALG3 in head and neck squamous cell carcinoma (HNSCC) remain unclear. We studied the mRNA expressions of PPFIA family members and ALG3 in a variety of tumor types compared with the normal controls using the Oncomine database along with meta-analyses of their expressions in HNSCC cancer cell line. The mRNA expressions of PPFIA family members and ALG3 in laryngeal squamous cell carcinoma cell line and normal laryngeal cell line were detected by quantitative real-time polymerase chain reaction. Based on the cBioportal database, we further studied mRNA expression alterations and co-occurrence relationships of the PPFIA family members and ALG3 in HNSCC. The relationship between PPFIA1 and ALG3 mRNA expression alterations and prognoses in patients with HNSCC was explored. We found that PPFIA1 and ALG3 were distinctively overexpressed at the mRNA level in HNSCC tissues compared with normal tissues, they had a significant co-occurrence relationship, their mRNA expressions were significantly higher than other PPFIA family members in laryngeal squamous cell carcinoma cell line, and their mRNA expressions were also significantly higher in laryngeal carcinoma cell line than in normal laryngeal cell line. Patients without both PPFIA1 and ALG3 mRNA expression alterations had better overall survival and disease/progression-free survival compared with patients with both PPFIA1 and ALG3 alterations. Based on these findings, PPFIA1 and ALG3 may play roles in oncogene expression in HNSCC. Their combined overexpression is significantly associated with poor survival outcomes. The relationship between them and the mechanism of action in head and neck cancers deserve further investigation.

Discovery of the Oncogenic Parp1, a Target of bcr-abl and a Potential Therapeutic, in mir-181a/PPFIA1 Signaling Pathway

miR-181a is downregulated in leukemia and affects its progression, drug resistance, and prognosis. However, the exact mechanism of its targets in leukemia, particularly in chronic myelogenous leukemia (CML), has not previously been established. Here, we use a multi-omics approach to demonstrate that protein tyrosine phosphatase, receptor type, f polypeptide, leukocyte common antigen (LAR) interacting protein (liprin), alpha 1 (PPFIA1) is a direct target for miR-181a in CML. Phospho-array assay shows that multiple phosphorylated proteins, particularly KIT signaling molecules, were downregulated in PPFIA1 inhibition. Additionally, PPFIA1 bound PARP1, a common molecule downstream of both PPFIA1 and BCR/ABL, to upregulate KIT protein through activation of nuclear factor kappa B (NF-κB)-P65 expression. Targeted inhibition of PPFIA1 and PARP1 downregulated c-KIT level, inhibited CML cell growth, and prolonged mouse survival. Overall, we report a critical regulatory miR-181a/PPFIA1/PARP1/NF-κB-P65/KIT axis in CML, and our preclinical study supports that targeted PPFIA1 and PARP1 may serve as a potential CML therapy.

Liprin-α1 modulates cancer cell signaling by transmembrane protein CD82 in adhesive membrane domains linked to cytoskeleton

Background

PPFIA1 is located at the 11q13 region commonly amplified in cancer. The protein liprin-α1 encoded by PPF1A1 contributes to the adhesive and invasive structures of cytoskeletal elements and is located at the invadosomes in cancer cells. However, the precise mechanism of liprin-α1 function in cancer progression has remained elusive.

Methods

Invasion regulating activity of liprin-α1 was examined by analyzing the functions of squamous cell carcinoma of head and neck (HNSCC) cell lines in three-dimensional collagen I after RNAi mediated gene knockdown. Transcriptome profiling and Gene Set Enrichment Analysis from HNSCC and breast cancer cells were used to identify expression changes relevant to specific cellular localizations, biological processes and signaling pathways after PPFIA1 knockdown. The significance of the results was assessed by relevant statistical methods (Wald and Benjamini-Hochberg). Localization of proteins associated to liprin-α1 was studied by immunofluorescence in 2D and 3D conditions. The association of PPFIA1 amplification to HNSCC patient survival was explored using The Cancer Genome Atlas data.

Results

In this study, we show that liprin-α1 regulates biological processes related to membrane microdomains in breast carcinoma, as well as protein trafficking, cell-cell and cell-substrate contacts in HNSCC cell lines cultured in three-dimensional matrix. Importantly, we show that in all these cancer cells liprin-α1 knockdown leads to the upregulation of transmembrane protein CD82, which is a suppressor of metastasis in several solid tumors.

Conclusions

Our results provide novel information regarding the function of liprin-α1 in biological processes essential in cancer progression. The results reveal liprin-α1 as a novel regulator of CD82, linking liprin-α1 to the cancer cell invasion and metastasis pathways.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0253-y) contains supplementary material, which is available to authorized users.

PPFIA1 is upregulated in liver metastasis of breast cancer and is a potential poor prognostic indicator of metastatic relapse

Although the oncogenic role of PPFIA1 (liprin-α1) in breast cancer has been reported, whether its dysregulation is associated with metastasis risk or survival outcomes in breast cancer patients is not clear. Our primary data showed that PPFIA1 expression was significantly higher in liver metastatic breast tumors than in the primary tumors. Then, we tried to pool previous annotated genomic data to assess the prognostic value of PPFIA1 in distant metastasis-free survival, the risk of metastatic relapse, and metastatic relapse-free survival in breast cancer patients by data mining in two large databases, Kaplan-Meier plotter and bc-GenExMiner 4.0. Results from Kaplan-Meier plotter showed that although high PPFIA1 expression was generally associated with decreased distant metastasis-free survival in estrogen receptor+ patients, subgroup analysis only confirmed significant association in estrogen receptor+/N- (nodal negative) group (median survival, high PPFIA1 group vs low PPFIA1 cohort: 191.21 vs 236.22 months; hazard ratio: 2.23, 95% confidence interval: 1.42-3.5, p < 0.001), but not in estrogen receptor+/N+ (nodal positive) group (hazard ratio: 1.63, 95% confidence interval: 0.88-3.03, p = 0.12). In estrogen receptor- patients, there was no association between PPFIA1 expression and distant metastasis-free survival, no matter in Nm (nodal status mixed), N-, or N+ subgroups. In bc-GenExMiner 4.0, Nottingham Prognostic Index- and Adjuvant! Online-adjusted analysis validated the independent prognostic value of PPFIA1 in metastatic risks in estrogen receptor+/N- patients. Based on these findings, we infer that high PPFIA1 expression might be an independent prognostic indicator of increased metastatic relapse risk in patients with estrogen receptor+/N- breast cancer, but not in estrogen receptor+/N+ or estrogen receptor- patients.

Amplification of the PPFIA1 gene region on 11q13 in oral squamous cell carcinomas (OSCC)

INTRODUCTION

Analyzing chromosomal amplifications delivers valuable information for identification of oncogenes. For carcinomas of the oral cavity only few genes have been identified in amplified regions. The aim of this study was to search genes in amplified regions as possible biomarkers and targets for novel therapies.

MATERIAL AND METHODS

DNA from 10 carcinomas of the floor of the oral cavity was examined using a 500K Array GeneChip (Affymetrix 6.0) to detect chromosomal losses, gains or amplifications. Suspicious alterations were validated on tissue microarrays using fluorescence in situ hybridization (FISH) with respective probes.

RESULTS

FISH-validation on tissue arrays confirmed PPFIA1 amplifications as one of the most frequent events (32.6%). High (10-20 signals) and low (<10 signals) amplification of PPFIA1 was found in 10.9% (5/46) and 21.7% (10/46) tumours, respectively. Fine mapping with overlapping FISH probes showed co-amplification of PPFIA1 and the Cyclin D1 gene which are approximately 600 kb apart from each other, likely in the same amplicon.

DISCUSSION

PPFIA1 was frequently co-amplified with the Cyclin D1 gene in oral carcinomas and could present a biomarker as well as a novel target for specific gene therapy. Further studies are necessary to investigate the role of PPFIA1 in development and pathogenesis of oral carcinomas.