Background: Glioblastoma (GBM) highly expresses Src tyrosine kinase involved in survival, proliferation, angiogenesis and invasiveness of tumor cells. Src activation also reduces reactive oxygen species (ROS) generation, whereas Src inhibitors are able to increase cellular ROS levels. Methods: Pro-oxidative effects of two pyrazolo[3,4-d]pyrimidine derivatives—Src tyrosine kinase inhibitors, Si306 and its prodrug pro-Si306—were investigated in human GBM cells U87 and patient-derived GBM-6. ROS production and changes in mitochondrial membrane potential were assessed by flow cytometry. The expression levels of superoxide dismutase 1 (SOD1) and 2 (SOD2) were studied by Western blot. DNA damage, cell death induction and senescence were also examined in GBM-6 cells. Results: Si306 and pro-Si306 more prominently triggered ROS production and expression of antioxidant enzymes in primary GBM cells. These effects were followed by mitochondrial membrane potential disruption, double-strand DNA breaks and senescence that eventually led to necrosis. Conclusion: Src kinase inhibitors, Si306 and pro-Si306, showed significant pro-oxidative potential in patient-derived GBM cells. This feature contributes to the already demonstrated anti-glioblastoma properties of these compounds in vitro and in vivo and encourages clinical investigations.

Drug resistance presents a major obstacle to the successful treatment of glioblastoma. Autophagy plays a key role in drug resistance, particularly in relation to targeted therapy, which has prompted the use of autophagy inhibitors to increase the effectiveness of targeted therapeutics. The ability of two Src tyrosine kinase inhibitors, Si306 and its prodrug pro-Si306, to induce autophagy was evaluated in the human glioblastoma cell line U87 and its multidrug-resistant counterpart U87-TxR. Autophagy markers were assessed by flow cytometry, microscopy, and Western blot, and induction of autophagy by these compounds was demonstrated after 3 h as well as 48 h. The effects of Si306 and pro-Si306 on cell proliferation and cell death were examined in the presence or absence of autophagy inhibition by bafilomycin A1. Combined treatments of Si306 and pro-Si306 with bafilomycin A1 were synergistic in nature, and the inhibition of autophagy sensitized glioblastoma cells to Src tyrosine kinase inhibitors. Si306 and pro-Si306 more strongly inhibited cell proliferation and triggered necrosis in combination with bafilomycin A1. Our findings suggest that modulation of Si306- and pro-Si306-induced autophagy can be used to enhance the anticancer effects of these Src tyrosine kinase inhibitors and overcome the drug-resistant phenotype in glioblastoma cells.

Lung cancer remains the leading cause of cancer death globally, with non-small cell lung cancer (NSCLC) accounting for the majority of cases. Multidrug resistance (MDR), often caused by ATP-binding cassette (ABC) transporters, represents a significant obstacle in the treatment of NSCLC. While genetic profiling has an important role in personalized therapy, functional assays that measure cellular responses to drugs are gaining in importance. We developed an automated microplate-based immunofluorescence assay for the evaluation of MDR markers ABCB1, ABCC1, and ABCG2 in cells obtained from NSCLC patients through high-content imaging and image analysis, as part of a functional diagnostic approach. This assay effectively discriminated cancer from non-cancer cells within mixed cultures, which is vital for accurate assessment of changes in MDR marker expression in different cell populations in response to anticancer drugs. Validation was performed using established drug-sensitive (NCI-H460) and drug-resistant (NCI-H460/R) NSCLC cell lines, demonstrating the assay’s capacity to distinguish and evaluate different MDR profiles. The obtained results revealed wide-ranging effects of various chemotherapeutic agents on MDR marker expression in different patient-derived NSCLC cultures, emphasizing the need for MDR diagnostics in NSCLC. In addition to being a valuable tool for assessing drug effects on MDR markers in different cell populations, the assay can complement genetic profiling to optimize treatment. Further assay adaptations may extend its application to other cancer types, improving treatment efficacy while minimizing the development of resistance.

The impact of tyrosine kinase inhibitors (TKIs) on multidrug resistance (MDR) in non-small cell lung carcinoma (NSCLC) is a critical aspect of cancer therapy. While TKIs effectively target specific signaling pathways of cancer cells, they can also act as substrates for ABC transporters, potentially triggering MDR. The aim of our study was to evaluate the response of 17 patient-derived NSCLC cultures to 10 commonly prescribed TKIs and to correlate these responses with patient mutational profiles. Using an ex vivo immunofluorescence assay, we analyzed the expression of the MDR markers ABCB1, ABCC1, and ABCG2, and correlated these data with the genetic profiles of patients for a functional diagnostic approach. NSCLC cultures responded differently to TKIs, with erlotinib showing good efficacy regardless of mutation burden or EGFR status. However, the modulation of MDR mechanisms by erlotinib, such as increased ABCG2 expression, highlights the challenges associated with erlotinib treatment. Other TKIs showed limited efficacy, highlighting the variability of response in NSCLC. Genetic alterations in signaling pathways associated with drug resistance and sensitivity, including TP53 mutations, likely contributed to the variable responses to TKIs. The relationships between ABC transporter expression, gene alterations, and response to TKIs did not show consistent patterns. Our results suggest that in addition to mutational status, performing functional sensitivity screening is critical for identifying appropriate treatment strategies with TKIs. These results underscore the importance of considering drug sensitivity, off-target effects, MDR risks, and patient-specific genetic profiles when optimizing NSCLC treatment and highlight the potential for personalized approaches, especially in early stages.

In the previous study fifteen jatrophane diterpenes were isolated from the Euphorbia nicaeensis latex. Fourteen of them have been shown to be potent P-glycoprotein (P-gp) inhibitor in two MDR cancer cells (NCI-H460/R and DLD1-TxR). The aim of this study was to determine whether and which jatrophane diterpenes can be isolated from the root of the plant, and then to examine their inhibition power on P-glycoprotein of selected cancer cell lines (NCI- -H460, DLD1, U87, NCI-H460/R, DLD1-TxR and U87-TxR). Two previously undescribed jatrophane diterpenes were isolated from the root of E. nicaeensis collected in Deliblato Sand (Serbia). The structures of the isolated compounds were determined using 1D and 2D NMR, as well as HRESIMS data. The results obtained by MTT assay showed different antitumor potential of these two jatrophanes. Compound 1 inhibited cell growth of non-small cell lung carcinoma cell lines NCI-H460 and NCI-H460/R, as well as glioblastoma cell lines U87 and U87-TxR, while jatrophane 2 was almost completely inactive in the suppression of cancer cell growth in a given range of concentrations. The obtained results also showed that the isolated compounds have an inhibitory effect on P-glycoprotein, as well as that their inhibitory potential is similar.

Background/Objectives: Non-small cell lung carcinoma (NSCLC) is characterized by its diverse molecular profiles and varying responses to treatment, highlighting the importance of precision medicine in optimizing therapeutic outcomes. A promising approach involves using patient-derived cellular models, which provide insights into the unique biology of individual tumors and their responsiveness to treatment. Methods: We established short-term primary cell cultures from thirteen patients with NSCLC of different subtypes and stages, including both cancer and stromal cells. To evaluate the ex vivo cytotoxicity and selectivity of eight chemotherapeutics and erlotinib, we employed an immunoassay, and the results were analyzed using an automated imaging system. Scoring of the obtained results was also performed. The ex vivo responses to cisplatin, etoposide, and paclitaxel were correlated with the patients’ responses to therapy. We used Kaplan–Meier analysis to assess progression-free survival (PFS) differences among patient groups. Results: NSCLC cells exhibited significant variability in their responses to drugs, with stromal cells demonstrating greater sensitivity. Tumors at stages I-III responded to multiple treatments, whereas stage IV cells showed considerable resistance. Erlotinib effectively reduced cancer cell growth at lower doses but plateaued at higher concentrations. The immunoassay indicated 67% sensitivity and 100% specificity in predicting patient responses to chemotherapy. Sensitivity to etoposide and paclitaxel correlated with progression-free survival (PFS). Conclusions: A personalized treatment strategy, such as our immunoassay based on the ex vivo responses of cancer patients’ cells, can guide treatment decisions and, in some cases, serve as surrogate biomarkers for tumor types that lack actionable biomarkers.