PPARγ antagonism as a new tool for preventing or overcoming endocrine resistance in luminal A breast cancers.

PURPOSE: This research investigates the role of PPARγ in the complex molecular events underlying the acquisition of resistance to tamoxifen (Tam) in luminal A breast cancer (BC) cells. Furthermore, it focuses on evaluating the possibility of repurposing Imatinib mesylate, an FDA-approved anticancer agent recently recognized also as a PPARγ antagonist, for the personalized therapy of endocrine-resistant BC with increased PPARγ expression. METHODS: Differential gene expression between parental and Tam-resistant MCF7 cells was assessed by RNA-seq followed by bioinformatics analysis and validation by RT-qPCR. PPARγ was downregulated by esiRNAs or inhibited by the antagonist GW9662. Cell viability and proliferation were measured by MTT and colony formation assays. Spheroids were prepared from parental and Tam-resistant MCF7 cells. Other luminal A BC cell lines resistant to Tam were generated. RESULTS: In MCF7-TamR cells, PPARγ and several of its target genes were significantly upregulated. Increased PPARγ expression was due to the modulation of its positive/negative transcriptional regulators. Downregulating PPARγ with esiRNAs or GW9662 effectively killed parental and Tam-resistant cells and spheroids. Imatinib revealed to be as effective as GW9662 in restoring Tam susceptibility of these cells. PPARγ overexpression was also observed in the newly-selected Tam-resistant luminal A BC cells, in which GW9662 and Imatinib restored their susceptibility to Tam. CONCLUSION: Our findings demonstrate that the overexpression of PPARγ is a frequent occurrence during acquisition of Tam resistance in luminal A BC cells, and that PPARγ antagonism represents an alternative therapeutic approach for the personalized treatment of BC showing dysregulation of this nuclear receptor.

Late presentation of chronic myeloid leukaemia patients in a low-income country: the prognostic implications and impact on treatment outcome.

BACKGROUND: In Nigeria, since 2002, Imatinib mesylate (glivec®) has been available freely to chronic myeloid leukaemia (CML) patients but only at a tertiary health care centre in the southwestern part of the country. Despite this, it is not readily accessible to many patients due to the distance and other challenges including low socioeconomic status and political problems, preventing timely access to specialist care. This study evaluated the effect of the baseline characteristics on the prognostic implication and treatment outcome of CML patients in Nigeria. METHOD: This study retrospectively evaluated the baseline characteristics, clinical presentations and treatment outcomes of 889 CML patients over 18 years (2002-2020). Of these, 576 (65%) patients had complete information with up-to-date BCR::ABL1 records. These 576 patients were categorized based on their responses to Imatinib therapy into three groups viz.; Optimal response (OR) defined as BCR::ABL1 ratio of < 0.1% or major molecular remission (≥ 3-log reduction of BCR::ABL1 mRNA or BCR::ABL1 ratio of < 0.1% on the International Scale), Suboptimal response (SR) with BCR::ABL ratio of 0.1-1%, and Treatment failure (TF) when MMR has not been achieved at 12 months. The variables were analyzed using descriptive and inferential statistics and a p-value < 0.05 was considered statistically significant. RESULTS: The result revealed a median age of 37 years at diagnosis with a male-to-female ratio of 1.5:1. The majority (96.8%) of the patients presented with one or more symptoms at diagnosis with a mean symptom duration of 12 ± 10.6 months. The mean Sokal and EUTOS scores were 1.3 ± 0.8 and 73.90 ± 49.09 respectively. About half of the patients presented with high-risk Sokal (49%) and EUTOS (47%) scores. Interestingly, both the Sokal (r = 0.733, p = 0.011) and EUTOS (r = 0.102, p = 0.003) scores correlated positively and significantly with the duration of symptoms at presentation. Based on response categorization, 40.3% had OR while 27.1% and 32.6% had SR and TF respectively. CONCLUSION: This study observed a low optimal response rate of 40.3% and treatment failure rate of 32.6% in our CML cohort while on first-line Imatinib therapy. This treatment response is strongly attributable to the long duration of symptoms of 12 months or more and high Sokal and EUTOS scores at presentation. We advocate prompt and improved access to specialist care with optimization of tyrosine kinase inhibitor therapy in Nigeria.

The interplay of knowledge, motivation, and treatment response in medication adherence among patients with chronic myeloid leukemia treated with Imatinib.

Chronic Myeloid Leukemia (CML) requires consistent medication adherence to Imatinib (IM) for optimal outcomes, however, adherence to oral chemotherapy is challenging. This observational study explores the relationship between patient knowledge, motivation, and adherence to IM therapy, and their collective impact on clinical outcomes. A prospective, observational study was conducted with 101 CML patients. The 6-Item Morisky Medication Adherence Scale (MMAS-6) was used to assess adherence, motivation, and knowledge levels. The study found that high motivation was significantly associated with lower BCR-ABL expression (p = 0.025). Patients with high knowledge and motivation had a 71% favorable response rate, compared to 0% in those with low knowledge and motivation (p = 0.01). As conclusion both patient motivation and knowledge are crucial for favorable treatment outcomes in CML. High levels of both significantly correlate with better clinical responses. Tailored interventions to enhance patient knowledge and motivation are essential.

Fibroblast Growth Factor 2 (FGF2) Activates Vascular Endothelial Growth Factor (VEGF) Signaling in Gastrointestinal Stromal Tumors (GIST): An Autocrine Mechanism Contributing to Imatinib Mesylate (IM) Resistance.

We showed previously that the autocrine activation of the FGFR-mediated pathway in GIST lacking secondary KIT mutations was a result of the inhibition of KIT signaling. We show here that the FGF2/FGFR pathway regulates VEGF-A/VEGFR signaling in IM-resistant GIST cells. Indeed, recombinant FGF2 increased the production of VEGF-A by IM-naive and resistant GIST cells. VEGF-A production was also increased in KIT-inhibited GIST, whereas the neutralization of FGF2 by anti-FGF2 mAb attenuated VEGFR signaling. Of note, BGJ 398, pan FGFR inhibitor, effectively and time-dependently inhibited VEGFR signaling in IM-resistant GIST T-1R cells, thereby revealing the regulatory role of the FGFR pathway in VEGFR signaling for this particular GIST cell line. This also resulted in significant synergy between BGJ 398 and VEGFR inhibitors (i.e., sunitinib and regorafenib) by enhancing their pro-apoptotic and anti-proliferative activities. The high potency of the combined use of VEGFR and FGFR inhibitors in IM-resistant GISTs was revealed by the impressive synergy scores observed for regorafenib or sunitinib and BGJ 398. Moreover, FGFR1/2 and VEGFR1/2 were co-localized in IM-resistant GIST T-1R cells, and the direct interaction between the aforementioned RTKs was confirmed by co-immunoprecipitation. In contrast, IM-resistant GIST 430 cells expressed lower basal levels of FGF2 and VEGF-A. Despite the increased expression VEGFR1 and FGFR1/2 in GIST 430 cells, these RTKs were not co-localized and co-immunoprecipitated. Moreover, no synergy between FGFR and VEGFR inhibitors was observed for the IM-resistant GIST 430 cell line. Collectively, the dual targeting of FGFR and VEGFR pathways in IM-resistant GISTs is not limited to the synergistic anti-angiogenic treatment effects. The dual inhibition of FGFR and VEGFR pathways in IM-resistant GISTs potentiates the proapoptotic and anti-proliferative activities of the corresponding RTKi. Mechanistically, the FGF2-induced activation of the FGFR pathway turns on VEGFR signaling via the overproduction of VEGF-A, induces the interaction between FGFR1/2 and VEGFR1, and thereby renders cancer cells highly sensitive to the dual inhibition of the aforementioned RTKs. Thus, our data uncovers the novel mechanism of the cross-talk between the aforementioned RTKs in IM-resistant GISTs lacking secondary KIT mutations and suggests that the dual blockade of FGFR and VEGFR signaling might be an effective treatment strategy for patients with GIST-acquired IM resistance via KIT-independent mechanisms.

Imatinib mesylate reduces c-MYC expression in double-hit lymphoma cells by suppressing inducible cytidine deaminase.

BACKGROUND: Double-hit lymphoma (DHL) with c-MYC gene translocation is highly aggressive and has a poor prognosis. In DHL cells, activation-induced cytidine deaminase (AID) promotes antibody class switch recombination (CSR), ultimately leading to c-MYC gene translocation caused by Myc/IgH DNA double-strand breaks. However, currently there is still no method to suppress the expression of AID. METHODS: In this study, we compared the clinical significance of AID expression in DHL, Additionally, two human double-hit lymphoma cell lines were used to analyze the effect of imatinib mesylate on c-MYC in vitro, and the therapeutic effect was also evaluated in xenograft mouse models. RESULTS: Imatinib mesylate downregulated the AID and c-MYC proteins in patients with chronic myelogenous leukemia associated with DHL. In addition, imatinib mesylate reduced AID and c-MYC expression in SU-DHL-4 and OCI-Ly18 DHL cells. Imatinib mesylate exerted significant inhibitory effects on the proliferation and metastasis of SU-DHL-4 and OCI-Ly18 cells. Finally, imatinib mesylate reduced not only tumor burden in DHL mouse models, but also AID and c-MYC expression in vivo. CONCLUSION: These findings reveal that imatinib mesylate effectively reduces the carcinogenic function of c-MYC in DHL, providing novel strategies for developing therapies targeting c-MYC-driven DHL.

A randomized study of 6 versus 3 years of adjuvant imatinib in patients with localized GIST at high risk of relapse.

BACKGROUND: The administration of adjuvant imatinib during 3 years is indicated after resection of primary localized GIST at high risk of recurrence, but many patients relapse afterwards. METHODS: IMADGIST (NCT02260505) was a multicenter, open-label, randomized phase III study evaluating the maintenance of imatinib for 3 more years (6-year arm) compared with interruption (3-year arm) from the day of randomization, conducted in the French Sarcoma Group. The primary endpoint was intent-to-treat disease-free survival. Secondary endpoints included overall survival, time to imatinib resistance, response after imatinib reintroduction at relapse, and safety. RESULTS: From 24 December 2014 to 4 April 2023, 136 patients aged ≥18 years, Eastern Cooperative Oncology Group performance status ≤2, with a localized gastrointestinal stromal tumor with an R0 or R1 surgery, and a risk of tumor recurrence ≥35% according to National Comprehensive Cancer Network (NCCN) risk classification were randomized in 14 centers. Sixty-five patients were randomized to the 3-year arm versus 71 to the 6-year arm. There were 68 males and females. Primary sites were gastric and small bowel in 60 (44%) and 64 (47%) patients, respectively. Respectively, 52 (38%) and 71 (52%) patients had a risk of relapse of 35%-70% and >70%. With a median follow-up of 55 months (interquartile range 46-59 months) after randomization, disease-free survival was significantly superior in the 6-year arm [hazard ratio: 0.40 (0.20-0.69), P = 0.0008]. Time to imatinib resistance, survival, adverse events, and quality of life were not different in the two arms. CONCLUSIONS: Three additional years of adjuvant imatinib reduces the risk of relapse in patients who have received 3 years of adjuvant imatinib with an acceptable tolerance.

QbD-based co-loading of paclitaxel and imatinib mesylate by protamine-coated PLGA nanoparticles effective on breast cancer cells.

Aim: Paclitaxel and imatinib mesylate are drugs used in the treatment of breast cancer. Conventional drug-delivery systems have limitations in the effective treatment of breast cancer using the drugs. Materials & methods: Combination index studies were used to identify the optimum ratio of both drugs showing maximum synergistic effect. Using a systematic quality-by-design approach, protamine-coated PLGA nanoparticles co-loaded with paclitaxel and imatinib mesylate were formulated. Further characterization and cell line evaluations were performed. Results: Encapsulation efficiency obtained was 92.54% for paclitaxel and 75.12% for imatinib mesylate. A sustained (24 h) and controlled zero-order drug release was obtained. Conclusion: Formulated nanoparticles had a low IC50 value and enhanced cellular uptake.

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Investigating the preferential interaction between imatinib mesylate and VEGF G-quadruplex DNA as therapeutic strategies for cancer treatment: Biophysical and molecular modelling approaches.

G-Quadruplex DNA (GQ-DNA) is one of the most important non-canonical nucleic acid structures. GQ-DNA forming sequences are present in different crucial genomic regions and are abundant in promoter regions of several oncogenes. Therefore, GQ-DNA is an important target for anticancer drugs and hence binding interactions between GQ-DNA and small molecule ligands are of great importance. Since GQ-DNA is a highly polymorphic structure, it is important to identify ligand molecules which preferentially target a particular quadruplex sequence. In this present study, we have used a FDA approved drug called imatinib mesylate (ligand) which is a selective tyrosine kinase inhibitor, successfully used for the treatment of chronic myelogenous leukaemia, gastrointestinal stromal tumours. Different spectroscopic techniques as well as molecular docking investigations and molecular simulations have been used to explore the interaction between imatinib mesylate with VEGF GQ DNA structures along with duplex DNA, C-Myc, H-Telo GQ DNA. We found that imatinib mesylate shows preferential interaction towards VEGF GQ DNA compared to C-Myc, H-Telo GQ and duplex DNA. Imatinib mesylate seems to be an efficient ligand for VEGF GQ DNA, suggesting that it might be used to regulate the expression of genes in cancerous cells.

Glycolysis in gastrointestinal stromal tumor: a brief overview.

Gastrointestinal stromal tumor (GIST) is the most prevalent mesenchymal tumor of the digestive tract. Its growth is primarily influenced by mutations in KIT or PDGFRA. Surgery is the primary treatment option for GIST; however, KIT inhibitors, such as imatinib, are used for inoperable cases. Resistance to imatinib is an upcoming challenge, especially because the effectiveness of alternative drugs is limited. Enhancement of the glycolysis pathway in cancer cells has been identified as a key feature in cancer. This unique metabolic activity has implications on tumor growth, prognosis, and resistance to therapy, even in GIST. Members of the glucose transporter (GLUT) family (particularly GLUT-1) play a significant role in GIST progression and response to treatment. Diagnostic imaging using 18F-fluorodeoxyglucose positron emission tomography/computed tomography, which enables visualization of glucose metabolism, can aid in GIST diagnosis and risk assessment. The interplay between glycolysis and GIST can lead to the development of various therapeutic strategies, especially those involving glycolysis-related molecules, such as hexokinase and lactate dehydrogenase. However, further research is required to understand the full spectrum of glycolysis in GIST and its therapeutic potential. Herein, we present an exhaustive overview and analysis of the role of glycolysis in GIST, especially as a therapeutic target.

A Unique Case of Mesenteric Gastrointestinal Stromal Tumor Presenting as an Acute Abdomen.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the digestive tract and arise from the interstitial cells of Cajal in the mesenteric plexus. These tumors can originate in any part of the GI tract; however, a higher burden has been observed in the stomach and small intestines. Mesenteric GISTs are exceedingly rare, with unique clinicopathological features and a poorer prognosis. Herein, we describe a unique case of a 66-year-old female with a remote history of appendectomy who presented to the emergency room complaining of severe abdominal pain and vomiting. On imaging, the patient was found to have a large inflammatory mass associated with small bowel loops, and the pathology confirmed a mesenteric GIST. The tumor was resected, and the genomic test results confirmed the KIT (exon 11) mutation. Although the tumor had a low mitotic rate, the tumor was large enough to warrant the initiation of adjuvant imatinib mesylate for 36 months with regular bloodwork and imaging.