PTEN insufficiency modulates ER+ breast cancer cell cycle progression and increases cell growth in vitro and in vivo

Pten knockout affects drug resistance differently in melanoma and kidney cancer

BACKGROUND

PTEN is a tumor suppressor that is often mutated and nonfunctional in many types of cancer. The high heterogeneity of PTEN function between tumor types makes new Pten knockout models necessary to assess its impact on cancer progression and/or treatment outcomes.

METHODS

We aimed to show the effect of CRISPR/Cas9-mediated Pten knockout on murine melanoma (B16 F10) and kidney cancer (Renca) cells. We evaluated the effect of PTEN deregulation on tumor progression in vivo and in vitro, as well as on the effectiveness of drug treatment in vitro. In addition, we studied the molecular changes induced by Pten knockout.

RESULTS

In both models, Pten mutation did not cause significant changes in cell proliferation in vitro or in vivo. Cells with Pten knockout differed in sensitivity to cisplatin treatment: in B16 F10 cells, the lack of PTEN induced sensitivity and, in Renca cells, resistance to drug treatment. Accumulation of pAKT was observed in both cell lines, but only Renca cells showed upregulation of the p53 level after Pten knockout. PTEN deregulation also varied in the way that it altered PAI-1 secretion in the tested models, showing a decrease in PAI-1 in B16 F10 Pten/KO and an increase in Renca Pten/KO cells. In kidney cancer cells, Pten knockout caused changes in epithelial to mesenchymal transition marker expression, with downregulation of E-cadherin and upregulation of Snail, Mmp9, and Acta2 (α-SMA).

CONCLUSIONS

The results confirmed heterogenous cell responses to PTEN loss, which may lead to a better understanding of the role of PTEN in particular types of tumors and points to PTEN as a therapeutic target for personalized medicine.

The impact of PIK3CA mutations and PTEN expression on the effect of neoadjuvant therapy for postmenopausal luminal breast cancer patients

BACKGROUND

There is pressing needs to find the biomarker in the selection of neoadjuvant therapy in postmenopausal luminal breast cancer patients. We examined the hypothesis that PIK3CA mutations and low phosphatase and tensin homolog (PTEN) expression affect the response to neoadjuvant therapy and prognosis in postmenopausal luminal breast cancer patients.

METHODS

Postmenopausal patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative breast cancer, up to stage II, who underwent neoadjuvant chemotherapy (NAC; n = 60) or neoadjuvant endocrine therapy (NAE; n = 55) were selected. PIK3CA exon 9 and exon 20 mutations were screened by high resolution melting analysis and confirmed by Sanger sequence. PTEN expression was evaluated by immunohistochemistry. The relationships among PIK3CA mutations, PTEN expression, clinicopathological features, the pathological effect of neoadjuvant therapy, recurrence-free survival (RFS) and overall survival were analyzed.

RESULTS

Among 115 patients, PIK3CA mutations and low PTEN expression before treatment were detected in 35 patients (30.4%) and in 28 patients (24.3%), respectively. In the NAC group, tumor with PIK3CA mutations showed significantly poorer response than tumor with PIK3CA wild-type (p = 0.03). On the other hand, in the NAE group, there was no significant difference in pathological therapeutic effect between tumor with PIK3CA mutations and tumor with PIK3CA wild-type (p = 0.54). In the NAC group, the log-rank test showed no difference in RFS between patients with PIK3CA mutations and PIK3CA wild-type (p = 0.43), but patients with low PTEN expression showed significantly worse RFS compared to patients with high PTEN expression (5 year RFS 0.64 vs. 0.87, p = 0.01). In the Cox proportional hazards model for RFS, PTEN expression, progesterone receptor, and pathological therapeutic effect were predictive factors for time to recurrence (All p < 0.05).

CONCLUSIONS

PIK3CA mutations are associated with resistance to NAC but do not affect the response to NAE. Low PTEN expression does not affect response to either NAC or NAE but correlates with shorter RFS in patients who received NAC. These biomarkers will be further evaluated for clinical use to treat postmenopausal luminal breast cancer patients.

Triple-high expression of phosphatase and tensin homolog (PTEN), estrogen receptor (ER) and progesterone receptor (PR) may predict favorable prognosis for patients with Type I endometrial carcinoma

Endometrial carcinoma (EC) is the most common malignant tumors in female derived from the endometrial epithelium. Several previous studies have described estrogen receptors (ER), progesterone Receptor (PR) and phosphatase and tensin homolog (PTEN) are associated with clinicopathological factors and prognosis in EC patients. However, during EC patients follow-up, we found that some EC patients with down-regulation of PTEN, but up-regulation of ER or PR , and some EC patients with down-regulation of ER or PR, but up-regulation of PTEN also had a poor prognosis. Therefore, to reveal the prognosis of EC patients with different phenotypes based on PTEN, ER and PR expression, 120 cases formalin-fixed paraffin-embedded EC tissues and 543 cases uterine corpus endometrial carcinoma (UCEC) patients from the cancer genome atlas (TCGA) UCEC datasets were analyzed. Results showed that EC tissues can be classified to PTEN^LER^LPR^L, PTEN^HER^LPR^L, PTEN^HER^HPR^H, PTEN^LER^HPR^H, PTEN^HER^HPR^L, PTEN^HER^LPR^H, and PTEN^LER^HPR^L phenotypes basing on IHC analysis. Additionally, EC patients with PTEN^LER^LPR^L showed high malignancy, while patients with PTEN^HER^HPR^H showed low malignancy. Therefore, combined detection of PTEN, ER, PR may help identify a small subset of EC with more aggressive behavior and may aid in risk stratification.

PUF60 accelerates the progression of breast cancer through downregulation of PTEN expression

Background

PUF60 is a splicing variant of far upstream element binding protein 1-interacting repressor, which is abnormally expressed in a variety of tumors and is closely involved in their progression. However, whether PUF60 participates in the occurrence and development of breast cancer remains unknown. Therefore, the objective of the current study is to explore the effects and mechanism of PUF60 in the progression of breast cancer.

Methods

PUF60 expression patterns in breast cancer tissues and cells were determined by RT-PCR and Western blotting. The relationship between PUF60 expression and patients' clinical features and outcome was evaluated to assess the potential of PUF60 as a marker for progression and prognosis prediction. CCK-8, flow cytometry, transwell and in vivo tumor formation assays were used to detect cell proliferation, apoptosis, migration, invasion and tumorigenesis. The effects of PUF60 on the activation of PTEN/PI3K/AKT were also evaluated by Western blotting and immunofluorescence assays.

Results

The expression of PUF60 was elevated in breast cancer tissue samples and cell lines, and its high expression was closely associated with the high incidence of lymph node metastasis and advanced TNM stage. Besides, upregulation of PUF60 with lentivirus infection significantly increased the growth, migration, and invasion and repressed the apoptosis of breast cancer HCC1937 and MDA-MB-231 cells, while silencing of PUF60 with shRNA showed the opposite results. Moreover, PUF60 upregulation promoted the expression of p-AKT, PI3K, and mTOR, while decreased PTEN expression through inhibiting its stability and enhancing its ubiquitination. Furthermore, upregulation of PUF60 promoted the tumorigenesis in vivo, whereas this effect was impaired when PTEN expression was upregulated in MDA-MB-231 and HCC1937 cells.

Conclusion

This study demonstrates that PUF60 is highly expressed in breast cancer; upregulation of PUF60 accelerates the progression of breast cancer through PTEN inhibition.

Protein Kinase Targets in Breast Cancer

With 1.67 million new cases and 522,000 deaths in the year 2012, breast cancer is the most common type of diagnosed malignancy and the second leading cause of cancer death in women around the world. Despite the success of screening programs and the development of adjuvant therapies, a significant percentage of breast cancer patients will suffer a metastatic disease that, to this day, remains incurable and justifies the research of new therapies to improve their life expectancy. Among the new therapies that have been developed in recent years, the emergence of targeted therapies has been a milestone in the fight against cancer. Over the past decade, many studies have shown a causal role of protein kinase dysregulations or mutations in different human diseases, including cancer. Along these lines, cancer research has demonstrated a key role of many protein kinases during human tumorigenesis and cancer progression, turning these molecules into valid candidates for new targeted therapies. The subsequent discovery and introduction in 2001 of the kinase inhibitor imatinib, as a targeted treatment for chronic myelogenous leukemia, revolutionized cancer genetic pathways research, and lead to the development of multiple small-molecule kinase inhibitors against various malignancies, including breast cancer. In this review, we analyze studies published to date about novel small-molecule kinase inhibitors and evaluate if they would be useful to develop new treatment strategies for breast cancer patients.

Screening of the prognostic targets for breast cancer based co-expression modules analysis

The purpose of the present study was to screen the prognostic targets for breast cancer based on a co-expression modules analysis. The microarray dataset GSE73383 was downloaded from the Gene Expression Omnibus (GEO) database, including 15 breast cancer samples with good prognosis and 9 breast cancer samples with poor prognosis. The differentially expressed genes (DEGs) were identified with the limma package. The Database for Annotation, Visualization and Integrated Discovery was used to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Furthermore, the co-expression analysis of DEGs was conducted with weighted correlation analysis. The interaction associations were analyzed with the Human Protein Reference Database and BioGRID. The protein-protein interactions (PPI) network was constructed and visualized by Cytoscape software. A total of 491 DEGs were identified in breast cancer samples with poor prognosis compared with those with good prognosis, and they were enriched in 85 GO terms and 4 KEGG pathways. 368 DEGs were co-expressed with others, and they were clustered into 10 modules. Module 6 was the most relevant to the clinical features, and 21 genes and 273 interaction pairs were selected out. Abnormal expression levels of required for meiotic nuclear division 5 homolog A (RMND5A) and angiopoietin-like protein 1 (ANGPTL1) were associated with a poor prognosis. It was indicated that SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily D, member 1, SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily D, member 1, dihydropyrimidinase-like 2, RMND5A and ANGPTL1 were potential prognostic markers in breast cancer, and the cell cycle may be involved in the regulation of breast cancer.

AFAP-1L2 influences proliferation and apoptosis of pancreatic cancer cells via PI3K/Akt pathway

AIM: To investigate the expression of actin filament-associated protein 1-like 2 (AFAP-1L2) in different pancreatic cancer cell lines, the effect of AFAP-1L2 on cell proliferation, cell cycle and apoptosis, and the possible mechanism.

METHODS: Western blot and real-time quantitative PCR (qRT-PCR) were used to detect the AFAP-1L2 protein and mRNA expression in PANC-1, MiaPaCa-2, Colo-357, BXPC-3, SW1990 and CFPAC-1 cell lines (having different differentiation degrees). siAFAP-1L2 plasmid was constructed and transfected into MiaPaCa-2 cell to downregulate the expression of AFAP-1L2. Proteins of the phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) pathway were detected by Western blot and qRT-PCR after siAFAP-1L2 transfection. Proliferation was detected by MTT assay. Cell cycle and apoptosis were detected by flow cytometry.

RESULTS: Western blot and qRT-PCR analyses showed that AFAP-1L2 was correlated with differentiation degree, and the expression was higher in cell lines with low differentiation than in those with moderate or high differentiation. PI3KCA protein expression in the siAFAP-1L2 group was lower than that in the MOCK and siRNA control groups (F = 20.16, P = 0.0022). α-Akt mRNA expression in the siAFAP-1L2 group was higher than that in the MOCK and siRNA control groups (F = 7.719, P = 0.0219); α-pAkt protein expression in the siAFAP-1L2 group was lower than that in MOCK and siRNA control groups (F = 5.507, P = 0.0439). PI3KCA mRNA expression in the siAFAP-1L2 group was lower than that in the AFAP-1L2 and siRNA control groups (F = 20.16, P = 0.0022). α-Akt mRNA expression in the siAFAP-1L2 group was higher than that in the MOCK and siRNA control groups (F = 6.068, P = 0.0362); α-pAkt mRNA expression in the siAFAP-1L2 group was lower than that in the MOCK and siRNA control groups (F = 10.33, P = 0.0114). MTT assay showed that the proliferation of MiaPaCa-2 cells at 48 h, 72 h, and 96 h was inhibited after siAFAP-1L2 transfection (F = 3.924, P < 0.05; F = 6.812, P < 0.01; F = 7.003, P < 0.01). Flow cytometry showed that cells in G₁ phase were increased, but those in G₂ and S phases were decreased (F = 4.87, 5.26, 4.94, P < 0.05 for all). The apoptosis rate of MiaPaCa-2 cell was increased after siAFAP-1L2 transfection (F = 7.231, P < 0.01).

CONCLUSION: AFAP-1L2 expression is associated with cell differentiation. AFAP-1L2 modulates cell proliferation, cell cycle and apoptosis via the PI3K/Akt pathway. AFAP-1L2 is a target candidate for pancreatic cancer therapy.