Cellular senescence is linked with chemotherapy resistance. Based on previous studies, GRP78 is a signal transducer in senescent cells. However, the association between GRP78 and stem cell phenotype remains unknown. Cisplatin treatment was clarified to induce cellular senescence leading to stemness induction via GRP78/Akt signal transduction. H460 cells were treated with 5 μM of cisplatin for 6 days to develop senescence. The colony formation assay and cell cycle analysis were performed. SA-β-galactosidase staining indicated senescence. Western blot analysis and RT-PCR were operated. Immunoprecipitation (IP) and immunocytochemistry assays (ICC) were also performed. Colony-forming activity was completely inhibited, and 87.07% of the cell population was arrested in the G2 phase of the cell cycle. mRNA of p21 and p53 increased approximately by 15.91- and 19.32-fold, respectively. The protein level of p21 and p53 was elevated by 9.57- and 5.9-fold, respectively. In addition, the c-Myc protein level was decreased by 0.2-fold when compared with the non-treatment control. Even though, the total of GRP78 protein was downregulated after cisplatin treatment, but the MTJ1 and downstream regulator, p-Akt/Akt ratio were upregulated by approximately 3.38 and 1.44-fold, respectively. GRP78 and MTJ1 were found at the cell surface membrane. Results showed that the GRP78/MTJ1 complex and stemness markers, including CD44, CD133, Nanog, Oct4, and Sox2, were concomitantly increased in senescent cells. MTJ1 anchored GRP78, facilitating the signal transduction of stem-like phenotypes. The strategy that could interrupt the binding between these crucial proteins or inhibit the translocation of GRP78 might beuseful for cancer therapy.

Cisplatin (CDDP) induces senescence characterized by senescence-associated secretory phenotypes (SASP) and the unfolded protein response (UPR). In this study, we investigated the proteins related to the UPR during the senescence cell fate. Strikingly, we found that one of the critical ER-resident proteins, GRP78/BiP, was significantly altered. Here we show that GRP78 levels differentially expressed depending on non-small lung cancer subtypes. GRP78 indeed regulates the evasion of senescence in adenocarcinoma A549 cells, in which the increased GRP78 levels enable them to re-proliferate after CDDP removal. Conversely, GRP78 is downregulated in the senescence H460 cells, making them lacking senescence evasion capability. We observed that the translational regulation critically contributed to the GRP78 protein levels in CDDP-induces senescence. Furthermore, the increased GRP78 level during senescence confers resistance to senolytic drug, Bortezomib, as observed by a twofold increase in IC₅₀ in A549 senescence cells compared to the wild-type. This observation is also consistent in the cells that have undergone genetic manipulation by transfection with pcDNA3.1(+)-GRP78/BiP plasmids and pSpCas9(BB)-2A-Puro containing guide RNA sequence targeting GRP78 exon 3 to induce the overexpression and downregulation of GRP78 in H460 cells, respectively. Our findings reveal a unique role of GRP78 on the senescence evasion cell fate and senolytic drug resistance after cisplatin-based chemotherapy.

New N-containing xanthone analogs of α-mangostin were synthesized via one-pot Smiles rearrangement. Using cesium carbonate in the presence of 2-chloroacetamide and catalytic potassium iodide, α-mangostin (1) was subsequently transformed in three steps to provide ether 2, amide 3, and amine 4 in good yields at an optimum ratio of 1:3:3, respectively. The evaluation of the biological activities of α-mangostin and analogs 2–4 was described. Amine 4 showed promising cytotoxicity against the non-small-cell lung cancer H460 cell line fourfold more potent than that of cisplatin. Both compounds 3 and 4 possessed antitrypanosomal properties against Trypanosoma brucei rhodesiense at a potency threefold stronger than that of α-mangostin. Furthermore, ether 2 gave potent SARS-CoV-2 main protease inhibition by suppressing 3-chymotrypsinlike protease (3CL^pro) activity approximately threefold better than that of 1. Fragment molecular orbital method (FMO–RIMP2/PCM) indicated the improved binding interaction of 2 in the 3CL^pro active site regarding an additional ether moiety. Thus, the series of N-containing α-mangostin analogs prospectively enhance druglike properties based on isosteric replacement and would be further studied as potential biotically active chemical entries, particularly for anti-lung-cancer, antitrypanosomal, and anti-SARS-CoV-2 main protease applications.

Recent advances in cancer biology have revolutionized the development of targeted and combination therapies, offering new avenues for improving cancer management. Among the central molecular regulators, the mammalian target of rapamycin (mTOR) plays a pivotal role in orchestrating cell growth, metabolism, and survival. Aberrant activation of mTOR signaling driven by genetic mutations or dysregulation of upstream pathways such as phosphoinositide 3-kinase (PI3K)/AKT has been strongly implicated in cancer progression, metastasis, and therapeutic resistance. Consequently, mTOR has emerged as a promising target for anticancer drug development. Although synthetic mTOR inhibitors, including rapamycin and its analogs (rapalogs), have shown clinical benefits, their limited efficacy and the emergence of resistance have highlighted the need for novel strategies. Natural product-derived mTOR modulators have gained increasing attention due to their multi-targeted mechanisms of action, simultaneously modulating mTOR and its upstream or parallel signaling networks. These compounds exhibit potent anticancer properties, including suppression of tumor growth, induction of apoptosis, and reversal of drug resistance. This review elucidates the biological functions of mTOR in tumorigenesis and delineates its regulatory mechanisms underlying malignant phenotypes. Furthermore, it emphasizes the therapeutic promise of natural products as a rich source of mTOR inhibitors, providing insights for the rational design of innovative cancer therapies and combination regimens.

Background: T-cell acute lymphoblastic leukemia (T-ALL) remains a challenging malignancy with limited targeted therapies. Natural phenanthrene derivatives represent a promising source of antileukemic agents. Objective: We screened a library of natural phenanthrene-type compounds to identify cytotoxic leads in Jurkat T-ALL cells and investigated the mechanisms underlying their activity, including potential synergy with the proteasome inhibitor bortezomib (BTZ). Methods: Jurkat cells were treated with thirteen natural compounds at 10 and 20 µM for 48 h; cell viability was assessed by WST-1 cell viability assay. Dose–response curves were generated to calculate IC₅₀ values. Apoptosis was evaluated by Hoechst 33342/PI staining and Annexin V/PI flow cytometry. Synergy with BTZ was analyzed using a fixed-ratio combination index (CI) approach and IC₅₀ shift analysis. ER stress signaling was characterized by Western blotting, quantitative RT-PCR of UPR genes (GRP78, ATF6), and immunoprecipitation of GRP78 followed by ubiquitin immunoblotting. Results: Among the compounds screened, Cypripedin showed the most potent cytotoxicity with an IC₅₀ of 6.52 µM. It induced a dose-dependent increase in apoptosis. Combination with BTZ yielded a CI < 0.5 and reduced BTZ IC₅₀ from 3.43 to 1.88 ng/mL. Cypripedin activated the unfolded protein response (UPR), modulated key ER stress markers including GRP78, p-PERK, p-eIF2α, p-JNK, and ATF6, downregulated UPR gene transcripts, and promoted GRP78 ubiquitination. Molecular docking predicted strong binding of Cypripedin to the GRP78 ATPase domain (Vina score −7.630 kcal/mol), supporting its mechanism of action. Conclusion: Cypripedin induces apoptosis in Jurkat T-ALL cells, synergizes with BTZ, and modulates ER stress through GRP78 ubiquitination. These findings support its further development as a potential T-ALL therapeutic.