Biological and therapeutic implications of RKIP in Gastrointestinal Stromal Tumor (GIST): an integrated transcriptomic and proteomic analysis

BACKGROUND

Gastrointestinal stromal tumors (GIST) represent a significant clinical challenge due to their metastatic potential and limited treatment options. Raf kinase inhibitor protein (RKIP), a suppressor of the MAPK signaling pathway, is downregulated in various cancers and acts as a metastasis suppressor. Our previous studies demonstrated low RKIP expression in GIST and its association with poor outcomes. This study aimed to expand on the previous findings and investigate the biological and therapeutic implications of RKIP loss on GIST.

METHODS

To validate the RKIP prognostic significance, its expression was evaluated by immunohistochemistry in 142 bona fide GIST cases. The functional role of RKIP was evaluated in vitro, using the GIST-T1 cell line, which was knocked out for RKIP. The biological and therapeutic implications of RKIP were evaluated by invasion, migration, apoptosis, and 2D / 3D viability assays. Additionally, the transcriptome and proteome of RKIP knockout cells were determined by NanoString and mass spectrometry, respectively.

RESULTS

Immunohistochemical analysis revealed the absence of RKIP in 25.3% of GIST cases, correlating with a tendency toward poor prognosis. Functional assays demonstrated that RKIP knockout increased GIST cells' invasion and migration potential by nearly 60%. Moreover, we found that RKIP knockout cells exhibited reduced responsiveness to Imatinib treatment and higher cellular viability in 2D and 3D in vitro models, as assessed by apoptosis-related protein expression. Through comprehensive genetic and proteomic profiling of RKIP knockout cells, we identified several putative RKIP-regulated proteins in GIST, such as COL3A1.

CONCLUSIONS

Using a multidimensional integrative analysis, we identified, for the first time in GIST, molecules and pathways modulated by RKIP that may potentially drive metastasis and, consequently, poor prognosis in this disease.

MicroRNA‑130a‑3p inhibition suppresses cervical cancer cell progression

MicroRNAs (miRNAs or miRs) play essential roles in the initiation and progression of human tumors, including cervical cancer. However, the mechanisms underlying their actions in cervical cancer remain unclear. The present study aimed to evaluate the functional role of miR‑130a‑3p in cervical cancer. Cervical cancer cells were transfected with a miRNA inhibitor (anti‑miR‑130a‑3p) and a negative control. Adhesion‑independent cell proliferation, migration and invasion were evaluated. The findings presented herein demonstrated that miR‑130a‑3p was overexpressed in HeLa, SiHa, CaSki, C‑4I and HCB‑514 cervical cancer cells. The inhibition of miR‑130a‑3p significantly reduced the proliferation, migration and invasion of cervical cancer cells. The canonical delta‑like Notch1 ligand (DLL1) was identified as a possible direct target of miR‑103a‑3p. The DLL1 gene was further found to be significantly downregulated in cervical cancer tissues. On the whole, the present study demonstrates that miR‑130a‑3p contributes to the proliferation, migration and invasion of cervical cancer cells. Therefore, miR‑130a‑3p may be used as a biomarker to determine cervical cancer progression.

Neuroprotective Properties of Chlorogenic Acid and 4,5-Caffeoylquinic Acid from Brazilian arnica (Lychnophora ericoides) after Acute Retinal Ischemia

Lychnophora is a genus of South American flowering plants in the daisy family, popularly known as "Brazilian arnica". It is used in traditional medicine as an anti-inflammatory and analgesic agent, whose active components are derived from chlorogenic acid (CGA) and C-flavonoids. Since the drugs currently used are ineffective to treat glaucoma, agents with antioxidant and anti-inflammatory properties may represent new alternatives in preventing cellular lesions in retinal ischemia. In this study, we report the neuroprotective effects of CGA and 4,5-di-O-[E]-caffeoylquinic (CQA) acid, isolated from Lychnophora plants, in a rodent glaucoma model. Wistar rats were administered intravitreally with 10 µg CGA or CGA, and then subjected to acute retinal ischemia (ISC) by increasing intraocular pressure (IPO) for 45 minutes followed (or not) by 15 minutes of reperfusion (I/R). Qualitative and quantitative analyses of neurodegeneration were performed using hematoxylin-eosin or Fluoro-Jade C staining protocols. All retinas submitted to ISC or I/R exhibited matrix disorganization, pyknotic nuclei, and pronounced vacuolization of the cytoplasm in the ganglion cell layer (GCL) and inner nuclear layer (INL). Pretreatment with CGA or CQA resulted in the protection of the retinal layers against matrix disorganization and a reduction in the number of vacuolized cells and pyknotic nuclei. Also, pretreatment with CGA or CQA resulted in a significant reduction in neuronal death in the GCL, the INL, and the outer nuclear layer (ONL) after ischemic insult. Our study demonstrated that CGA and CQA exhibit neuroprotective activities in retinas subjected to ISC and I/R induced by IPO in Wistar rats.

RAD50 Deficient in a Breast Cancer Model Predicts Sensitivity to PARP Inhibitors

BACKGROUND

Breast and ovarian tumors with pathogenic variants in BRCA1 or BRCA2 genes are more sensitive to poly (ADP-ribose) polymerase inhibitors (PARPi) treatment than wildtype tumors. Pathogenic variants in non-BRCA1/2 homologous recombination repair genes (HRR) also concede sensitivity to PARPi treatment. RAD50 participates in the Mre11-RAD50-Nbn (MRN) complex of the HRR pathway and plays an important role in DNA repair.

OBJECTIVE

The objective of this study is to evaluate whether RAD50 protein deficiency modulates the PARPi response in breast cancer cell lines.

METHODS

T47D breast cancer cell line was modified using small interfering RNA and CRISPR/Cas9 technology, to knockout the RAD50 gene. PARPi response (niraparib, olaparib and rucaparib alone or in combination with carboplatin), in T47D and T47D-edited clones, was evaluated by cell viability, cell cycle, apoptosis and protein expression analyses.

RESULTS

Treatment with niraparib and carboplatin exerted a synergistic effect on T47D-RAD50 deficient cells and an antagonistic effect on T47D cells parental. Cell cycle analysis demonstrated an increase in the G2/M population in cells treated with niraparib or rucaparib alone or in combination with carboplatin. T47D-RAD50 deficient cells treated with rucaparib and carboplatin exhibited twofold levels in late apoptosis, also showing differences in PARP activation. All T47D RAD50 deficient clones treated with niraparib or rucaparib combined with carboplatin, or rucaparib alone showed increased levels of H2AX phosphorylation.

CONCLUSIONS

T47D RAD50 deficient cells treated with PARP inhibitors alone or in combination with carboplatin showed cell cycle arrest in the G2/M phase, leading to death by apoptosis. Thus, RAD50 deficiency may be a good biomarker for predicting PARPi response.

Semi-Synthetic Ingenol Derivative from Euphorbia tirucalli Inhibits Protein Kinase C Isotypes and Promotes Autophagy and S-phase Arrest on Glioma Cell Lines

The identification of signaling pathways that are involved in gliomagenesis is crucial for targeted therapy design. In this study we assessed the biological and therapeutic effect of ingenol-3-dodecanoate (IngC) on glioma. IngC exhibited dose-time-dependent cytotoxic effects on large panel of glioma cell lines (adult, pediatric cancer cells, and primary cultures), as well as, effectively reduced colonies formation. Nevertheless, it was not been able to attenuate cell migration, invasion, and promote apoptotic effects when administered alone. IngC exposure promoted S-phase arrest associated with p21CIP/WAF1 overexpression and regulated a broad range of signaling effectors related to survival and cell cycle regulation. Moreover, IngC led glioma cells to autophagy by LC3B-II accumulation and exhibited increased cytotoxic sensitivity when combined to a specific autophagic inhibitor, bafilomycin A1. In comparison with temozolomide, IngC showed a mean increase of 106-fold in efficacy, with no synergistic effect when they were both combined. When compared with a known compound of the same class, namely ingenol-3-angelate (I3A, Picato^®), IngC showed a mean 9.46-fold higher efficacy. Furthermore, IngC acted as a potent inhibitor of protein kinase C (PKC) activity, an emerging therapeutic target in glioma cells, showing differential actions against various PKC isotypes. These findings identify IngC as a promising lead compound for the development of new cancer therapy and they may guide the search for additional PKC inhibitors.

In vitro screening of cytotoxic activity of euphol from Euphorbia tirucalli on a large panel of human cancer-derived cell lines

A large number of classic antineoplastic agents are derived from plants. Euphorbia tirucalli L. (Euphorbiaceae) is a subtropical and tropical plant, used in Brazilian folk medicine against many diseases, including cancer, yet little is known about its true anticancer properties. The present study evaluated the antitumor effect of the tetracyclic triterpene alcohol, euphol, the main constituent of E. tirucalli in a panel of 73 human cancer lines from 15 tumor types. The biological effect of euphol in pancreatic cells was also assessed. The combination index was further used to explore euphol interactions with standard drugs. Euphol showed a cytotoxicity effect against several cancer cell lines (IC₅₀ range, 1.41–38.89 µM), particularly in esophageal squamous cell (11.08 µM) and pancreatic carcinoma cells (6.84 µM), followed by prostate, melanoma, and colon cancer. Cytotoxicity effects were seen in all cancer cell lines, with more than half deemed highly sensitive. Euphol inhibited proliferation, motility and colony formation in pancreatic cancer cells. Importantly, euphol exhibited synergistic interactions with gemcitabine and paclitaxel in pancreatic and esophageal cell lines, respectively. To the best of our knowledge, this study constitutes the largest in vitro screening of euphol efficacy on cancer cell lines and revealed its in vitro anti-cancer properties, particularly in pancreatic and esophageal cell lines, suggesting that euphol, either as a single agent or in combination with conventional chemotherapy, is a potential anti-cancer drug.

Abstract A29: Omics profile of two immortalized Brazilian glioblastoma cell cultures

Background: Glioblastomas are the most frequent and deadly brain tumors. Genomic alterations, as well as its high heterogeneity, are important features of these tumors. Despite the advances in the biology of these tumors, it is essential to develop models, such as primary tumor cell lines, that better mimic their genomic diversity and therapeutic behavior. We aimed to characterize the molecular profile of two (HCB2 and HCB151) established immortalized glioblastoma cell lines.

Methods: Immortalized glioblastoma cell lines, HCB2 and HCB151, were established from Barretos Cancer Hospital patients diagnosed with glioblastoma. The cells were cultured with DMEM+10%BFS+1%PS and molecularly characterized, using arrayCGH, next-generation sequencing (Ion Torrent) and validated by Sanger sequencing, miRNA expression and CNV using the NanoString platform, and BD Lyoplate™ Human Cell Surface Marker Screening Panel using Accuri™ C6 flow cytometer. The tumorigenic capacity was further determined in vivo by the chicken chorioallantoic membrane (CAM) assay, and its response to temozolomide-based chemotherapy was done by MTS.

Results: The aCGH analysis showed that the most frequent events was the gain of chromosome 7 and loss of chromosomes 10, 13, and 17p. HCB2 exhibited mutations in the TERT gene, while HCB151 showed mutations in the TP53, PTEN, LZTR1, and TERT genes. The immortalized cultures present an unique miRNA profile. The CAM assay showed that HCB2 and HCB151 were able to form vascularized tumors, with HCB151 more aggressive than HCB2. In addition, both HCB2 (IC50>1000 µM) and HCB151 (IC50=783 µM) showed resistance to TMZ when compared to commercial glioblastomas cell lines (23-441 µM).

Conclusion: The present findings showed that the immortalized glioblastoma cell lines showed classic genomic features of glioblastomas and exhibited a similar biologic behavior, suggesting that these cell lines are a good model for glioblastoma preclinical studies.

Citation Format: Adriana Cruvinel-Carloni, Renato José da Silva-Oliveira, Viviane Aline Oliveira-Silva, Marcela Nunes Rosa, Lucas Tadeu Bidinotto, Gustavo Noriz Berdinarelli, Raul Torrieri, Adriane Feijó Evangelista, Olga Catarina Martinho, Vera Mónica Gonçalves, Carlos Clara, Gisele Caravina de Almeida, Rui Manuel Reis. Omics profile of two immortalized Brazilian glioblastoma cell cultures [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A29.

Cytotoxic activity of semi-synthetic ingenol derived from Euphorbia tirucalli on a large panel of human cancer cell lines

e13559

Background: The latex from Euphorbia tirucalli is used in Brazil as anticancer and other disease as folk treatment; however, little is known about its anticancer proprieties. We report in vitro activity of 3 semi-synthetic ingenol compounds derived from E. tirucalli, ingenol A (ingenol-3-trans-cinnamate), ingenol B (3-caproyl-ingenol) and ingenol C (ingenol-3-dodecanoate), against a large panel of human cancer cell lines. Methods: Anti-tumor effects of the 3 semi-synthetic compounds were assessed using MTS assays on 77 cancer lines from 13 tumor models, such as breast, colon, bladder, prostate, lung, pancreas, esophagus, glioblastoma, melanoma, head and neck and cervical cancer. Additionally, we evaluate the its potential combinatorial value with temozolomide (TMZ) in gliomas. Ongoing experiments will identify potential drug target(s) by assessing changes in global protein expression. Results: Ingenol A, B and C exhibited dose-dependent and time-dependent cytotoxic effects. Amongst the derived tested, ingenol C displayed the best activity across the tumor cell lines. In comparison with TMZ, ingenol C showed a median of 136 fold higher efficacy, range 15-511 fold, in the glioma cell lines analyzed. Conclusions: The semi-synthetic ingenol compounds, in particular the ingenol C, demonstrated a potent anti-tumor activity on all cancer cell lines evaluated. Our findings may provide insight into designing ingenol-based therapies for cancer patients. [Table: see text]

Cytotoxic effect of euphol from Euphorbia tirucalli on a large panel of human cancer cell lines

e13557

Background: The tetracyclic triterpene alcohol euphol is the main constituent found in the sap of Euphorbia tirucalli. In Brazil its latex is used as anticancer and other diseaseas folk treatment, yet, little is known about its anticancer proprieties. We aimed to study the antitumor effect of euphol on a large panel of human cancer cell lines. Methods: Anti-tumor effects of euphol in vitro were assessed using MTS assays on 77 human cancer lines from13 solid tumor models, such as breast, colon, bladder, prostate, lung, pancreas, esophagus, glioblastoma, melanoma, head and neck and cervical cancer. Additionally, we evaluate the its potential combinatorial value with temozolomide in gliomas. Ongoing experiments will identify potential drug target(s) by assessing changes in global protein expression. Results: Euphol exhibited dose and time-dependent cytotoxic effects on all cancer cell lines analyzed. Among each tumor type, the distinct cell line exhibited a heterogeneous profile of response to euphol. Esophageal squamous cell carcinoma and pancreatic carcinomas showed the most sensitive profile. In comparison with temozolomide, euphol showed a median of 30 fold higher efficacy, range 5-167 fold, in the glioma cell lines analyzed (Table). Conclusions: Euphol demonstrated potent anti-tumor activity on the majority of cancer cell lines evaluated. Our findings may provide insight into the tailoring designing of euphol-based therapies for cancer patients. [Table: see text]