Low PTEN Research Articles

The oncogenic axis YAP/MYC/EZH2 impairs PTEN tumor suppression activity enhancing lung tumorigenicity

The tumor suppressor PTEN (phosphatase and tensin homolog deleted in chromosome 10) is genetically deleted or downregulated in many cancer types. Loss of PTEN protein expression is frequently found in lung cancer while genetic alterations are less abundant. PTEN expression is regulated at multiple genetic and epigenetic levels and even partial reduction of its expression increases cancer occurrence. We show that YAP and TAZ cooperate with EZH2, and MYC to transcriptionally repress onco-suppressor genes, including PTEN, in non-small cell lung cancer (NSCLC) cells. YAP/TAZ-EZH2-MYC transcriptional regulators form a nuclear complex that represses PTEN transcription, while their combinatorial targeting restores PTEN expression, attenuates NSCLC cell growth, and prevents compensatory responses induced by single treatments. Datasets analysis of NSCLC patients revealed that PTEN expression is negatively correlated to YAP/TAZ, EZH2 and MYC and that low expression of PTEN is predictive of poor prognosis, especially at earlier stages of the disease. These findings highlight the repressive role of the YAP/TAZ-EZH2-MYC axis on tumor-suppressor genes and offer a potential therapeutic strategy for lung cancer patients with low PTEN levels.

Dysfunction of PTEN-Associated MicroRNA Regulation: Exploring Potential Pathological Links in Type 1 Diabetes Mellitus.

Background and Objectives: Type 1 Diabetes Mellitus (T1DM) is an autoimmune disease with T cell-mediated pathogenesis of pancreatic β-cell destruction, leading to insulin deficiency. MicroRNAs such as miR-223 and miR-106b, along with PTEN, have been reported to participate in the pathophysiology of diabetes and its complications. The current study has explored the expression of miR-223, miR-106b, and PTEN and their association with various clinical and biochemical parameters in subjects diagnosed with T1DM. Materials and Methods: Sixty T1DM patients (two groups as uncomplicated/ with microalbuminuria) and fifty healthy volunteers, age- and sex-matched, were enrolled in this study. The fasting venous blood samples were collected, and PTEN and miRNAs (miR-223 and miR-106b) levels were measured by ELISA and real-time PCR, respectively. Results: The PTEN levels of patients with microalbuminuria were significantly lower than those of patients without microalbuminuria, while those of miR-223 and miR-106b were significantly increased in the T1DM group compared with the healthy control group (p < 0.001). ROC analysis indicated that PTEN, miR-223, and miR-106b could be potential biomarkers for diagnosing T1DM with high specificity but with variable sensitivities. Also, PTEN and miR-223 were negatively correlated with r =-0.398 and p < 0.0001, indicating that they were interrelated in their role within the T1DM pathophysiology. Conclusions: In the current study, it has been shown that the circulating levels of PTEN, miR-223, and miR-106b are significantly changed in T1DM patients and may back their potential to be used as non-invasive biomarkers for the diagnosis and monitoring of T1DM. Low PTEN protein expression was related to high miR-223 expression, indicating involvement of these miRNA in the regulation of PTEN. Further studies should be performed to clarify the exact mechanisms and possible clinical applications of these molecules.

The usefulness of evaluating PTEN expression for accurate grading of phyllodes tumors

Phyllodes tumors (PTs) are classified as benign, borderline, or malignant based on histologic characteristics. However, because histological criteria are subjective and diagnosis requires integrating multiple findings, discrepancies often occur between observers. Therefore, it is necessary to discover biomarkers based on the molecular characteristics of PTs. This study aimed to identify dysregulated microRNAs (miRNAs) in PTs through miRNA profiling and determine whether expression of their target genes could be useful as PT biomarkers. MiRNA profiling was performed on 13 PTs (three malignant, three borderline, seven benign) and six fibroadenomas, and predicted target genes of dysregulated miRNAs were selected using three computation algorithms. The expression of two miRNAs, miR-155 and miR-200c, was 1.69-fold and 1.61-fold higher, respectively, in borderline and malignant PT groups than in the benign PT group (p < 0.05). KEGG pathway analysis revealed that the 374 target genes of these two miRNAs (miR-155 and miR200c) participated in several signaling pathways, adherens junction, cell cycle, and pathway in cancer. Immunohistochemical staining for PTEN, one of candidate target genes of miR-200c, was performed on whole slides of PT tissue classified as malignant (n = 9), borderline (n = 12), or benign (n = 21). Stromal tumor cells of high-grade PTs (borderline and malignant) had significantly lower PTEN expression than those of low-grade PTs (benign) (p-value ≤0.001). Semiquantitative analysis of PTEN expression, score 0–8, revealed that it correlated with histologic findings. Low PTEN expression (s-score of 6 or less) was used as a diagnostic criterion for high-grade PTs, it showed 100 % sensitivity and 95.2 % specificity in 42 cases of PTs. Currently, PT grading based solely on subjective histologic findings is challenging, but semiquantitative PTEN expression analysis could provide a more accurate and objective way to grade PTs.

Loss of phosphatase and tensin homolog expression castration-sensitive prostate cancer predicts outcomes in men after prostatectomy.

This study aimed to investigate the potential for using the phosphatase and tensin homolog (PTEN) gene as a prognostic marker in post-prostatectomy patients with castration-sensitive prostate cancer (PCa). A total of 180 patients with castration-sensitive PCa who underwent radical prostatectomy at our institution were included in this study. PTEN expression was evaluated using immunohistochemistry, and patients were classified into two groups based on the staining intensity: PTEN-Normal and PTEN-Loss. The association between PTEN expression and biochemical recurrence was analyzed using the Cox proportional hazards model. Patients in the PTEN-Loss group had a higher risk of biochemical recurrence (hazard ratio, 4.642; 95% confidence interval, 2.137-10.083; p < 0.001) and a lower recurrence-free rate compared to the PTEN-Normal group (35% vs. 75%). In addition to clinicopathological factors, such as the serum prostate-specific antigen level, Gleason score, and T stage, evaluation of PTEN expression improved the prediction of biochemical recurrence after prostatectomy (area under the curve, 0.577 vs. 0.688). Low PTEN expression is a significant predictor of biochemical recurrence in patients with castration-sensitive PCa who have already undergone prostatectomy.

MiRNA encoded PTEN’s impact on clinical-pathological features and prognosis in osteosarcoma: A systematic review and meta-analysis

Background Osteosarcoma (OSC) is considered one of the most common malignant bone tumours in adolescents. Due to OSC’s poor prognosis, a comprehensive approach to exploring these aspects is highly needed to improve the survival probability of OSC. In this study, we tried to explore the significance of miRNA-encoded PTEN for clinical-pathological features and prognostic value in OSC. Method We performed this systematic review and meta-analysis using articles and sources published between 2013 and 2023 from six databases (Scopus, PubMed, ProQuest, Science Direct, Sage Pub, and Cochrane). Included studies were clinical cross-sectional studies. Other study designs, articles not written in English, without full text, and not relevant—were excluded. Then, ROBINS-I is used to evaluate the distance. The results are constructed according to the PICOS criteria in a table. The expression of miRNA related to OSC is assessed in the meta-analysis as the main outcome to determine its ability as a diagnostic and prognostic agent for OSC. This systematic review followed the PRISMA guidelines. Results A total of 17 studies were included in the final screening. The meta-analysis showed significantly increased (p &lt; 0.00001) miRNA expression in patients with OSC compared to healthy controlled with pooled md (2.85) (95% CI: 2.69, 3.02; I2 = 22%, p = 0.20), the high inverse correlation (p &lt; 0.001) between miRNA and PTEN expression was shown as mean effect size (-0.681) (95% CI: -0.787, -0.536; I2 = 75%, p &lt; 0.0001), and the prognostic evaluation of OS was significantly increased in low expression miRNA (p &lt; 0.00001) with pooled OR. Conclusion Fifteen miRNAs from 17 studies were found, and together with PTEN expression, they may serve as potential prognostic biomarkers for OSC. High-level levels of miRNA expression are correlated with low PTEN expression, leading to a bad prognosis for OSC.

Effect of oncolytic Newcastle disease virus harboring PTEN gene on pancreatic adenocarcinoma growth through inhibition of PI3K/mTOR signaling and promotion of apoptosis.

49 Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive and intractable cancer, warranting the need for more effective therapies. Cell proliferation, progression, and severity in PDAC are highly activated owing to KRAS mutations and low PTEN expression. Methods: A recombinant Newcastle disease virus (rNDV) harboring PTEN (rNDV-PTEN) was constructed to infect PDAC cells to artificially induce PTEN expression. The cancer killing effect of the rNDV-PTEN virus was observed in an in vitro assay, and 107.0 pfu/dose(0.1 ml) of the rNDV-PTEN virus was inoculated through intravenous injection into a PANC-1 cell transplanted mouse to prove the tumor growth inhibition effect. Apoptotic signaling-related proteins were analyzed with Western blotting and qPCR assays based on the mRNA. During the treatment, biomarkers were also analyzed. Results: Factitious PTEN expression in KRAS-mutated PDAC cells following rNDV-PTEN infection lowered PI3K/AKT/mTOR signaling, induced PDAC cell death, and suppressed tumor growth. PTEN overexpression promoted apoptotic and autophagic signaling pathways in PANC-1 cells and orthotopic xenograft mice. rNDV-PTEN has substantial cancer cell-killing effects and inhibits tumor growth. rNDV-PTEN injection into animals did not elicit an immune response against rNDV and improved blood parameters, such as glucose, triglyceride, and total cholesterol levels. Conclusions: rNDV-PTEN showed a strong tumor-suppressive effect on PDAC, which was caused by an abnormally activated PI3K/AKT/mTOR signaling pathway due to KRAS mutations and PTEN loss. We also showed that rNDV-PTEN is relatively safe for use in cancer therapy. Further studies using patient-derived PDAC cells with the same genetic background, as well as more extensive animal safety tests, are required to demonstrate rNDV-PTEN as a PDAC therapeutic. However, PTEN gene-containing rNDV may be a very promising therapeutic candidate for pancreatic cancer treatment.

Diallyl disulfide antagonizes DJ-1 mediated proliferation, epithelial-mesenchymal transition, and chemoresistance in gastric cancer cells.

Diallyl disulfide (DADS), an organic component of allicin abstracted from garlic, possesses multi-target antitumor activity. DJ-1 performs a vital function in promoting AKT aberrant activation via down-regulating phosphatase and tensin homologue (PTEN) in tumors. It is unknown the involvement of DJ-1 in epithelial-mesenchymal transition (EMT) of gastric cancer (GC) cells. The purpose of this study is to investigate whether diallyl disulfide (DADS) intervenes in the role of DJ-1 in GC. Based on the identification that the correlation between high DJ-1 and low PTEN expression in GC was implicated in clinical progression, we illuminated that down-regulation of DJ-1 by DADS aided in an increase in PTEN expression and a decrease in phosphorylated AKT levels, which was in line with the results manifested in the DJ-1 knockdown and overexpressed cells, concurrently inhibiting proliferation, EMT, migration, and invasion. Furthermore, the antagonistic effects of DADS on DJ-1 were observed in in vivo experiments. Additionally, DADS mitigated the DJ-1-associated drug resistance. The current study revealed that DJ-1 is one of potential targets for DADS, which hopefully provides a promising strategy for prevention and adjuvant chemotherapy of GC.

RETRACTED ARTICLE: csi-miR-96-5p delivered by Clonorchis sinensis extracellular vesicles promotes intrahepatic cholangiocarcinoma proliferation and migration via the ferroptosis-related PTEN/SLC7A11/GPX4 axis

BackgroundClonorchis sinensis (CS) is classified as a group 1 carcinogen and can cause intrahepatic cholangiocarcinoma (ICC). CS extracellular vesicles (CsEVs) play important roles in mediating communication between parasitic helminths and humans. Ferroptosis is a novel cell death mechanism that is mainly induced by lipid peroxidation and iron overload. However, the role of CsEVs in the regulation of ferroptosis in ICC remains unclear. This study aimed to explore the role of CS-secreted miR-96-5p (csi-miR-96-5p) delivered by CsEVs in ICC progression and ferroptosis.MethodsTissue samples were collected from ICC patients with CS infection (CS-ICC) or without CS infection (NC-ICC). The levels of csi-miR-96-5p and PTEN gene were determined by quantitative polymerase chain reaction (qPCR) and western blotting, and survival analysis was performed. CsEVs were isolated and identified by ultracentrifugation and transmission electron microscopy. Lentiviruses were used to establish stable cell lines with csi-miR-96-5p mimic expression, PTEN overexpression (PTEN-EXO) and PTEN CRISPR/Cas9-based knockout (PTEN-KO) and their respective negative controls. Cell proliferation was assessed by performing Cell Counting Kit-8 assays in vitro and in a tumor xenograft model in vivo, and cell migration was assessed by performing Transwell assays. Erastin is used to induce ferroptosis. Ferroptosis levels were evaluated using biomarkers.ResultsHigh csi-miR-96-5p and low PTEN expression was observed in CS-ICC tissues and was associated with poor overall survival. csi-miR-96-5p was highly enriched in CsEVs and was taken up by ICC cells. csi-miR-96-5p mimics or PTEN-KO significantly promoted the growth and migration of ICC cells in vitro and in vivo, whereas PTEN-EXO exerted the opposite effect. Mechanistically, csi-miR-96-5p mimics or PTEN-KO inhibited erastin-induced ferroptosis, including reducing the accumulation of Fe2+, lipid reactive oxygen species, and malondialdehyde, increasing the GSH/GSSG ratio and levels of SLC7A11 and GPX4, whereas PTEN-EXOs exerted the opposite effect.Conclusionscsi-miR-96-5p delivered by CsEVs reduced ferroptosis by regulating the expression of the PTEN/SLC7A11/GPX4 axis, thereby promoting ICC proliferation and migration. For the first time to our knowledge, we found that CS miRNAs could promote tumor development through ferroptosis.Graphical

1791P Molecular profiling and prognostic relevance of low PTEN expression in metastatic hormone-sensitive prostate cancer patients

1791P Molecular profiling and prognostic relevance of low PTEN expression in metastatic hormone-sensitive prostate cancer patients

Lower PTEN may be associated with CD8+ T cell exhaustion in diffuse large B-cell lymphoma

Initially discovered in chronic viral infection and then extended to tumor, 'T-cell exhaustion' is a broad term describing the response of T cells to chronic antigen stimulation. By definition, whether T-cell exhaustion occurs in diffuse large B-cell lymphoma (DLBCL) remains largely unknown because little has been described. Here, the immune-suppressing checkpoint molecules involved in T-cell exhaustion, including PD-1, PD-L1, TIM-3 and TIGIT, whose expression levels were analyzed in DLBCL, were retrieved from the GEPIA database. Compared with the normal control, CD8A, TNFA, IFNG and GZMA were markedly elevated in DLBCL, indicating that infiltrated CD8+ T cells predominate in DLBCL. Meanwhile, inhibitory immune checkpoints, such as PD-1, PD-L1, TIGIT and TIM-3 were drastically higher in DLBCL. PTEN, WNT2 and DKK3 expression were also appraised. It was revealed that PTEN was lower in DLBCL, without being statistically significant. In contrast with PTEN, DKK3 and WNT2 were shown to be pronouncedly higher in DLBCL relative to the normal control. Prognostically, only TIGIT was found to be associated with overall survival in DLBCL. Collectively, all the data we curetted from the GEPIA and TIMER 2.0 databases explicitly indicate that CD8+ T cell exhaustion took place, which may be linked with lower PTEN in DLBCL. To the best of our knowledge, this is the first bioinformatic report explicitly proposing that CD8+ T cell exhaustion occurs in DLBCL, which may be associated with lower PTEN.

Development and independent validation of a predictive gene expression signature based on RB1, PTEN, and TP53 in patients with metastatic hormone-sensitive metastatic prostate cancer (mHSPC).

5083 Background: Alterations on the tumor suppressor genes (TSG) RB1, PTEN and TP53 are associated with treatment resistance and aggressive clinical evolution of prostate cancer patients (pts). Here, we developed and validated a TSG gene expression signature in mHSPC pts. Methods: This is a multicenter retrospective biomarker study in mHSPC pts. Mutations on TSG were assessed by targeted sequencing, mRNA expression by nCounter platform and protein by IHC in FFPE tumor samples. Expression data of the training cohort were used to establish the cut-off applied to the other cohorts. TSGlow was considered when ≥2 out of 3 TSG presented low expression and TSGwt in the remaining cases. CHAARTED trial pts with microarray data (Hamid, Ann Oncol, 2021) were analyzed as an independent validation cohort. TSG signature was correlated with castration resistance-free survival (CRPC-FS) (primary endpoint) and overall survival (OS) by Kaplan Meier and multivariate Cox analysis. Results: 218 pts were included: 125 treated with ADT + docetaxel (ADT+D) and 93 with ADT. 160 pts from the CHAARTED dataset were analyzed (84 with ADT+D and 76 with ADT). ADT+D pts with available TSG gene expression and targeted sequencing were considered as the training cohort (n=54). Pts with low PTEN and RB1 gene expression had lower IHC expression (p&lt;0.01). Low PTEN pts had a higher frequency of PTEN mutations (p&lt;0.05). TSGlow (25.9%) pts had a worse CRPC-FS (14.3 vs 21.7 months (m); HR 2.2 (95% CI, 1.1 – 4.4) p=0.022). In the internal validation cohort of ADT+D-treated pts (n=71), TSGlow (9.9%) correlated with a worse CPRC-FS (11.7 vs 20 m, p=0.027) and OS (27.6 vs 58.1 m, p=0.012). TSGlow was independently associated with CPRC-FS (HR 2.7 (95% CI, 1.2 – 6.1) p=0.02) and OS (HR 3.7 (95% CI, 1.3 – 10.1) p=0.012). In the ADT cohort (TSGlow 21.5%), no differences in either CRPC-FS or OS were observed. When analyzed together the ADT+D and ADT cohorts, we observed that TSGwt pts treated with ADT+D had the largest CRPC-FS (21.6 m; p=0.014) and OS (58.1 m; p=0.029), while TSGlow pts receiving ADT+D had a CRPC-FS and OS similar to ADT-treated pts. Similarly, in the CHAARTED dataset, TSGlow (20.2%) pts treated with ADT+D had a worse CPRC-FS (14.8 vs 29.4 m, HR 2.2 (95% CI, 1.1 – 4.3) p=0.023) and OS (32.9 vs 57.4 m, HR 2.2 (95% CI, 1 – 4.5) p=0.04). TSGlow (35.5%) was not predictive of either CRPC-FS or OS in ADT-treated pts. Analyzing together ADT+D and ADT pts, TSGwt pts treated with ADT+D had the best CRPC-FS and OS (p&lt;0.01). Conclusions: Our results suggest that a TSGlow expression may predict the lack of benefit to taxanes in mHSPC pts, which may be useful to personalize the treatment. [Table: see text]

Hyperphosphorylated PTEN exerts oncogenic properties

PTEN is a multifaceted tumor suppressor that is highly sensitive to alterations in expression or function. The PTEN C-tail domain, which is rich in phosphorylation sites, has been implicated in PTEN stability, localization, catalytic activity, and protein interactions, but its role in tumorigenesis remains unclear. To address this, we utilized several mouse strains with nonlethal C-tail mutations. Mice homozygous for a deletion that includes S370, S380, T382 and T383 contain low PTEN levels and hyperactive AKT but are not tumor prone. Analysis of mice containing nonphosphorylatable or phosphomimetic versions of S380, a residue hyperphosphorylated in human gastric cancers, reveal that PTEN stability and ability to inhibit PI3K-AKT depends on dynamic phosphorylation-dephosphorylation of this residue. While phosphomimetic S380 drives neoplastic growth in prostate by promoting nuclear accumulation of β-catenin, nonphosphorylatable S380 is not tumorigenic. These data suggest that C-tail hyperphosphorylation creates oncogenic PTEN and is a potential target for anti-cancer therapy.

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

BackgroundThere 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.MethodsPostmenopausal 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.ResultsAmong 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).ConclusionsPIK3CA 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.

Abstract 1124: PTEN loss confers resistance to anti-PD-1 therapy in NSCLC by increasing tumor infiltration of T regulatory cells

Abstract Immune checkpoint inhibitors (ICIs) targeting PD-L1/PD-1 have dramatically improved the management of NSCLC patients. Nevertheless, more than 50% patients will present primary resistance or will develop secondary resistance within 12-25 months after treatment initiation. The mechanisms of resistance to ICIs may depend on tumor-intrinsic molecular/genetic alterations that generate an immunosuppressive tumor microenvironment (isTME). Using In silico analyses (TCGA and AACR-GENIE cohorts), and protein expression analysis in our institutional CIMA-CUN cohort, we have shown that &amp;gt;50% LUSC and ~28% LUAD tumors exhibited reduced PTEN mRNA/protein levels. Patients with PTEN-low tumors had higher levels of CXCL10, PD-L1 and PD-L2. In a cohort of stage IV NSCLC patients treated with ICIs, we found that patients with low tumor PTEN levels were significantly associated with worse OS (p=0.021). We have developed and characterized a Pten-null LUSC model using UN680 cells, which was also refractory to anti-PD-1 when implanted in syngeneic mice. Pten loss led to a deregulation of multiple pathways related to immunosuppression, with a positive enrichment in “IL-6/JAK/STAT3” and “TNF-α via NFkB” hallmarks, identified by GSEA. Tumors from the Pten-null LUSC model were highly metastatic and fibrotic, and secreted TGF-β/CXCL10, thus favoring conversion of CD4+ lymphocytes into Tregs. Human/mouse PTEN-low tumors were enriched in Tregs and immunosuppressive genes. Importantly, treatment of mice bearing Pten-null tumors with TLR agonists+anti-TGF-β, aimed to alter this isTME, led to tumor rejection and immunological memory in 100% of mice. Our results demonstrate that lack of PTEN causes immunotherapy resistance in LUSC by establishing an isTME that can be reversed therapeutically. Citation Format: Francisco Exposito, Miriam Redrado, Maeva Houry, Katherine Hastings, Magdalena Molero-Abraham, Teresa Lozano, Jose L. Solorzano, Julian Sanz Ortega, Vera Andradas, Ramon Amat, Esther Redin, Sergio Leon, Naroa Legarra, Javier García, Diego Serrano, Karmele Valencia, Camila Robles-Oteiza, Giorgia Foggetti, Enriqueta Felip, Juan J. Lasarte, Luis Paz-Ares, Jon Zugazagoitia, Katerina Politi, Luis M Montuenga, Alfonso Calvo. PTEN loss confers resistance to anti-PD-1 therapy in NSCLC by increasing tumor infiltration of T regulatory cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1124.

Pleomorphic giant cell carcinoma of the prostate: clinicopathologic analysis and oncological outcomes

We report on the clinicopathologic features of 27 pleomorphic giant cell carcinoma (PGCC) cases of the prostate identified in 20 patients with an age range of 51 to 84 years (68 ± 9; median 71 years). Charlson comorbidity index ranged from 3 to 12. Serum PSA ranged from 4.30 to 662 ng/mL (median 13 ng/mL). On histologic examination, bizarre giant cells with pleomorphic nuclei characterized pleomorphic giant cell carcinoma of the prostate. PGCC component was present in 5% to 100%, with half of the patients presenting with ≥ 20%. Half of the patients initially presented with T4 and 26% with T3 disease. All patients were considered Gleason scores of 9 to 10 (ISUP grade 5). A combination of hormone therapy with chemotherapy with or without radiation therapy was applied in 68% of patients. On follow-up, 14 patients (52%) were alive with disease (1–69 months) or dead of disease (1–38 months). Patients diagnosed earlier with lower TNM stage had longer survival than those diagnosed at a later T-stage or with metastatic disease (p = 0.02). The percentage of PGCC was not related to survival in the current study. Molecular alterations in 3 samples showed a microsatellite-stable disease with low tumor mutation burden and variable PTEN, PTCH1, KDM6A, ARv7, and PIK3CA loss/alteration, TP53 mutation, TMPRSS2-ERG fusion, and MYC, PIK3CB, RICTOR, or IRS2 amplification. Our findings suggest that PGCC is a rare and aggressive subtype of prostate carcinoma whose recognition may steer clinicians to adopt more aggressive treatments and investigate new therapeutic strategies.

PTEN regulates invasiveness in pancreatic neuroendocrine tumors through DUSP19-mediated VEGFR3 dephosphorylation

BackgroundPhosphatase and tensin homolog (PTEN) is a tumor suppressor. Low PTEN expression has been observed in pancreatic neuroendocrine tumors (pNETs) and is associated with increased liver metastasis and poor survival. Vascular endothelial growth factor receptor 3 (VEGFR3) is a receptor tyrosine kinase and is usually activated by binding with vascular endothelial growth factor C (VEGFC). VEGFR3 has been demonstrated with lymphangiogenesis and cancer invasiveness. PTEN is also a phosphatase to dephosphorylate both lipid and protein substrates and VEGFR3 is hypothesized to be a substrate of PTEN. Dual-specificity phosphatase 19 (DUSP19) is an atypical DUSP and can interact with VEGFR3. In this study, we investigated the function of PTEN on regulation of pNET invasiveness and its association with VEGFR3 and DUSP19.MethodsPTEN was knocked down or overexpressed in pNET cells to evaluate its effect on invasiveness and its association with VEGFR3 phosphorylation. In vitro phosphatase assay was performed to identify the regulatory molecule on the regulation of VEGFR3 phosphorylation. In addition, immunoprecipitation, and immunofluorescence staining were performed to evaluate the molecule with direct interaction on VEGFR3 phosphorylation. The animal study was performed to validate the results of the in vitro study.ResultsThe invasion and migration capabilities of pNETs were enhanced by PTEN knockdown accompanied with increased VEGFR3 phosphorylation, ERK phosphorylation, and increased expression of epithelial–mesenchymal transition molecules in the cells. The enhanced invasion and migration abilities of pNET cells with PTEN knockdown were suppressed by addition of the VEGFR3 inhibitor MAZ51, but not by the VEGFR3-Fc chimeric protein to neutralize VEGFC. VEGFR3 phosphorylation is responsible for pNET cell invasiveness and is VEGFC-independent. However, an in vitro phosphatase assay failed to show VEGFR3 as a substrate of PTEN. In contrast, DUSP19 was transcriptionally upregulated by PTEN and was shown to dephosphorylate VEGFR3 via direct interaction with VEGFR3 by an in vitro phosphatase assay, immunoprecipitation, and immunofluorescence staining. Increased tumor invasion into peripheral tissues was validated in xenograft mouse model. Tumor invasion was suppressed by treatment with VEGFR3 or MEK inhibitors.ConclusionsPTEN regulates pNET invasiveness via DUSP19-mediated VEGFR3 dephosphorylation. VEGFR3 and DUSP19 are potential therapeutic targets for pNET treatment.

S-palmitoylation of PCSK9 induces sorafenib resistance in liver cancer by activating the PI3K/AKT pathway.

Sorafenib is currently the first-line treatment for advanced hepatocellular carcinoma (HCC). However, sorafenib resistance remains a significant challenge. Aberrant AKT signaling activation is a crucial mechanism driving sorafenib resistance in HCC. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a vital role in antitumor immune responses. In this study, we demonstrate that aberrant PCSK9 upregulation promotes cell proliferation and sorafenib resistance in HCC by inducing AKT-S473 phosphorylation. After palmitoylation at cysteine 600, the binding affinity between PCSK9 and tensin homolog (PTEN) is dramatically increased, inducing lysosome-mediated PTEN degradation and subsequent AKT activation. We identify zinc finger DHHC-type palmitoyltransferase 16 (ZDHHC16) as a palmitoyltransferase that promotes PCSK9 palmitoylation at cysteine 600. We also develop a biologically active PCSK9-derived peptide that competitively inhibits PCSK9 palmitoylation, suppressing AKT phosphorylation and augmenting the antitumor effects of sorafenib in HCC.

Capicua (CIC) mutations in gliomas in association with MAPK activation for exposing a potential therapeutic target.

2056 Background: Capicua (CIC) Gene is a tumor suppressor, transcriptional repressor, and a member of the high mobility (HMG)-box protein family. CIC is a negative regulator of MAPK and RTK pathways; inactivating CIC mutations (mut) occur in approximately 40% of oligodendrogliomas (OLIG) and less frequently in other gliomas putatively activating downstream signaling. With a goal to identify potential novel treatment options for various gliomas, we explored key signaling pathways associated with CIC mut. Methods: Consecutive glioma tumors were analyzed using Next-Gen DNA sequencing (NextSeq, 592 genes or NovaSeq, whole-exome), RNA sequencing (NovaSeq, WTS ) and IHC (Caris Life Sciences, Phoenix, AZ). Immune cell fraction was calculated by QuantiSeq; MAPK activation score (MPAS) was evaluated using RNAseq data. A comparison was made using Chi2 or Fisher’s-exact test with correction for multiple-comparison (q) using Benjamini-Hochberg. Results: A total of 196 (3.7%) tumors with CIC mut were seen in 5266 gliomas tumors analyzed, with the highest prevalence seen in OLIG (143 of 285, 50.2%). There was no difference between grade 3 (73 of 142, 51.4%) and grade 2 OLIG (70 of 143, 49%). CIC mut were infrequent in astrocytomas (16 of 829, 1.9%; grade 3, 12/510 or 2.4%; grade 2, 4/261 or 1.5%; grade 1, 0/58). CIC mut were present in glioblastomas (24/2753 or 0.6%), gliosarcomas (1/128 or 0.8%), and other mixed subtypes (12/185 or 6.5%). CIC mut were associated with higher prevalence of IDH1/2 mut (92% in CIC-mut vs. 17% in wild type), MGMT promoter methylation (97% vs. 47%), FUBP1 mut (32% vs. 1%) but lower PTEN mut (1% vs. 25%) and TP53 mut (12% vs. 39%) (all q &lt; 0.05). Significant mutual exclusivity for CIC mut and MAPK pathway drivers observed: EGFR amplification (1.5% vs. 27%) , EGFR mut (0.5% vs. 12.6%), NF1 mut (4% vs. 18%) (all q &lt; 0.05). BRAF mut rate was similar in CIC-mut or wild-type (1% vs. 3%, p = ns). Although associated with a higher tumor mutation burden (cutoff &gt; = 10 mut/MB, 13% vs. 3%), a lower prevalence of PDL1 expression (1% vs. 16%) and lower M1 macrophage infiltration were seen (all q &lt; 0.05). Similar effects were seen when stratifying by oligodendroglial and astrocytic histology. CIC mut were associated with increased MPAS score in OLIG (p = 0.01), particularly when compared to tumors lacking additional MAPK drivers (p = 0.001). This effect was not seen in astrocytic tumors, although EGFR alterations (including CNA, EGFRvIII, EGFR fusion and mut) were independently associated with increased MPAS scores (p &lt; 0.001). Conclusions: CIC mut were frequent in oligodendrogliomas but occurred rarely in other glioma tumors and are associated with favorable prognostic markers. RNA expression analysis suggests CIC mut is associated with MAPK activation in OLIG, as are EGFR alterations in astrocytomas. Targeted inhibition of this pathway in selected gliomas may be a promising therapeutic avenue and should be explored further.

Systemic Deficiency of PTEN Accelerates Breast Cancer Growth and Metastasis.

Mutation or loss of the tumor suppressor gene PTEN or its functional status in tumor stromal cells may affect tumor occurrence, development, invasion, and metastasis, in which, however, the role of overall low PTEN expression, mutation, or deletion in the tumor-bearing host has rarely been reported. Breast cancer is a common highly invasive metastatic tumor. We therefore treated mouse breast cancer 4T1 cells with the specific PTEN inhibitor VO-OHpic to study the effects of PTEN suppression or deletion on malignant behavior in vivo and in vitro. VO-OHpic effectively inhibited PTEN gene/protein expression in 4T1 cells, accelerated cell proliferation, and enhanced cell migration and invasion. We also transplanted 4T1 cells with VO-OHpic-inhibited PTEN into mice to create orthotopic and metastatic breast cancer models. The proliferation of 4T1 cells in mouse mammary gland was increased and distant metastasis was enhanced, with metastatic foci in the lung, liver, and intestinal tract. In addition, injection of mice with VO-OHpic to inhibit PTEN in the overall microenvironment accelerated the proliferation of transplanted 4T1 cells and enhanced distant metastasis and the formation of metastatic tumors. Metastatic foci formed in the lung, liver, intestine, thymus, and brain, and PTEN levels in the organ/tissues were negatively associated with the formation of metastatic foci. Similarly, inoculation of PTEN-deficient 4T1 cells into systemic PTEN-inhibited mice further enhanced the orthotopic growth and distant metastasis of 4T1 breast cancer. VO-OHpic inhibition of PTEN in 4T1 cells was also associated with significantly increased phosphorylation of Akt and phosphoinositide 3-kinase (PI3K), suggesting that inhibition of PTEN could activate the PI3K-Akt pathway, as a key signaling pathway regulating cell proliferation and death. These results confirmed that functional loss or deletion of the tumor suppressor gene PTEN significantly enhanced the proliferation, invasion, and metastasis of 4T1 cells. Systemic decrease or deletion of PTEN in the organism or organ/tissue microenvironment was conducive to the proliferation of breast cancer cells in situ and distant metastasis. These results suggest that, as well the PTEN in cancer cells the systemic microenvironment PTEN intensely mediates the proliferation, invasion and metastasis of mouse breast cancer cells via regulating the PI3K-Akt signaling pathway.

MiR-96-5p targets PTEN to mediate sunitinib resistance in clear cell renal cell carcinoma

A multiple receptor tyrosine kinase inhibitor, sunitinib, is a first-line therapy for clear cell renal cell carcinoma (CCRCC). Unfortunately, it has the major challenges of low initial response rate and resistance after about one year of treatment. Here we evaluated a microRNA (miRNA) and its target responsible for sunitinib resistance. Using miRNA profiling, we identified miR-96-5p upregulation in tumors from sunitinib-resistant CCRCC patients. By bioinformatic analysis, PTEN was selected as a potential target of miR-96-5p, which showed low levels in tumors from sunitinib-resistant CCRCC patients. Furthermore, PTEN and miR-96-5p levels were negatively correlated in a large The Cancer Genome Atlas kidney renal clear cell carcinoma cohort and high miR-96 and low PTEN represented poor prognosis in this cohort. Additionally, four-week sunitinib treatment increased miR-96-5p and decreased PTEN only in tumors from a sunitinib-resistant patient-derived xenograft model. We found a novel miR-96-5p binding site in the PTEN 3′ UTR and confirmed direct repression by luciferase reporter assay. Furthermore, we demonstrated that repression of PTEN by miR-96-5p increased cell proliferation and migration in sunitinib-treated cell lines. These results highlight the direct suppression of PTEN by miR-96-5p and that high miR-96-5p and low PTEN are partially responsible for sunitinib resistance and poor prognosis in CCRCC.