A ruthenium(II) complex containing a p-cresol group induces apoptosis in human cervical carcinoma cells through endoplasmic reticulum stress and reactive oxygen species production

Subcellular targeting strategies for protein and peptide delivery

Cytosolic delivery of proteins and peptides provides opportunities for effective disease treatment, as they can specifically modulate intracellular processes. However, most of protein-based therapeutics only have extracellular targets and are cell-membrane impermeable due to relatively large size and hydrophilicity. The use of organelle-targeting strategy offers great potential to overcome extracellular and cell membrane barriers, and enables localization of protein and peptide therapeutics in the organelles. Although progresses have been made in the recent years, organelle-targeted protein and peptide delivery is still challenging and under exploration. We reviewed recent advances in subcellular targeted delivery of proteins/peptides with a focus on targeting mechanisms and strategies, and highlight recent examples of active and passive organelle-specific protein and peptide delivery systems. This emerging platform could open a new avenue to develop more effective protein and peptide therapeutics.

The unfolded protein response-glutathione metabolism axis: A novel target of a cycloruthenated complexes bypassing tumor resistance mechanisms

Platinum-based drugs remain the reference treatment for gastric cancer (GC). However, the frequency of resistance, due to mutations in TP53 or alterations in the energy and redox metabolisms, impairs the efficacy of current treatments, highlighting the need for alternative therapeutic options. Here, we show that a cycloruthenated compound targeting the redox metabolism, RDC11, induces higher cytotoxicity than oxaliplatin in GC cells and is more potent in reducing tumor growth in vivo. Detailed investigations into the mode of action of RDC11 indicated that it targets the glutathione (GSH) metabolism, which is an important drug resistance mechanism. We demonstrate that cycloruthenated complexes regulate the expression of enzymes of the transsulfuration pathway via the Unfolded Protein Response (UPR) and its effector ATF4. Furthermore, RDC11 induces the expression of SLC7A11 encoding for the cystine/glutamate antiporter xCT. These effects lead to a lower cellular GSH content and elevated oxygen reactive species production, causing the activation of a caspase-independent apoptosis. Altogether, this study provides the first evidence that cycloruthenated complexes target the GSH metabolism, neutralizing thereby a major resistance mechanism towards platinum-based chemotherapies and anticancer immune response.

Lysosome-targeted ruthenium(II) complex encapsulated with pluronic® F-127 induces oncosis in A549 cells

Transition metal complexes with characteristics of unique packaging in nanoparticles and remarkable cancer cell cytotoxicity have emerged as potential alternatives to platinum-based antitumor drugs. Here we report the synthesis, characterization, and antitumor activities of three new Ruthenium complexes that introduce 5-fluorouracil-derived ligands. Notably, encapsulation of one such metal complex, Ru3, within pluronic® F-127 micelles (Ru3-M) significantly enhanced Ru3 cytotoxicity toward A549 cells by a factor of four. To determine the mechanisms underlying Ru3-M cytotoxicity, additional in vitro experiments were conducted that revealed A549 cell treatment with lysosome-targeting Ru3-M triggered oxidative stress, induced mitochondrial membrane potential depolarization, and drastically reduced intracellular ATP levels. Taken together, these results demonstrated that Ru3-M killed cells mainly via a non-apoptotic pathway known as oncosis, as evidenced by observed Ru3-M-induced cellular morphological changes including cytosolic flushing, cell swelling, and cytoplasmic vacuolation. In turn, these changes together caused cytoskeletal collapse and activation of porimin and calpain1 proteins with known oncotic functions that distinguished this oncotic process from other cell death processes. In summary, Ru3-M is a potential anticancer agent that kills A549 cells via a novel mechanism involving Ru(II) complex triggering of cell death via oncosis.

Cyclometalated iridium(III) complexes as anti-breast cancer and anti-metastasis agents via STAT3 inhibition

Breast cancer is the most commonly diagnosed cancer and second‑leading cause of cancer deaths in women. Signal transducer and activator of transcription 3 (STAT3) plays a critical role in promoting breast cancer cell proliferation, invasion, angiogenesis, and metastasis, and the high expression of STAT3 is related to the occurrence and poor chemotherapy sensitivity of breast cancer. Iridium(III) complexes Ir-PTS-1- 4 containing a pterostilbene-derived ligand were synthesized to inhibit the STAT3 pathway in breast cancer. Ir-PTS-4 inhibited the proliferation of breast cancer cells by suppressing the expression of phosphorylated STAT3 and STAT3-related cyclin D1, arresting cell cycle in the S-phase, inducing DNA damage and reactive oxygen species (ROS) generation, eventually leading to autophagic cell death. The cell metastasis and invasion were also inhibited after Ir-PTS-4 treatment. Besides, Ir-PTS-4 exhibited excellent anti-proliferation activity in 3D multicellular tumor spheroids, showing potential for the treatment of solid tumors. This work presents the rational design of metal-based anticancer agents to block the STAT3 pathway for simultaneously inhibiting breast cancer proliferation and metastasis.

Possible Effects of Uremic Toxins p-Cresol, Indoxyl Sulfate, p-Cresyl Sulfate on the Development and Progression of Colon Cancer in Patients with Chronic Renal Failure

Chronic kidney disease (CKD) induces several systemic effects, including the accumulation and production of uremic toxins responsible for the activation of various harmful processes. Gut dysbiosis has been widely described in CKD patients, even in the early stages of the disease. The abundant discharge of urea and other waste substances into the gut favors the selection of an altered intestinal microbiota in CKD patients. The prevalence of bacteria with fermentative activity leads to the release and accumulation in the gut and in the blood of several substances, such as p-Cresol (p-C), Indoxyl Sulfate (IS) and p-Cresyl Sulfate (p-CS). Since these metabolites are normally eliminated in the urine, they tend to accumulate in the blood of CKD patients proportionally to renal impairment. P-CS, IS and p-C play a fundamental role in the activation of various pro-tumorigenic processes, such as chronic systemic inflammation, the increase in the production of free radicals and immune dysfunction. An up to two-fold increase in the incidence of colon cancer development in CKD has been reported in several studies, although the pathogenic mechanisms explaining this compelling association have not yet been described. Based on our literature review, it appears likely the hypothesis of a role of p-C, IS and p-CS in colon cancer development and progression in CKD patients.

Milk Exosomal miR-27b Worsen Endoplasmic Reticulum Stress Mediated Colorectal Cancer Cell Death

The relationship between dietary constituents and the onset and prevention of colorectal cancer (CRC) is constantly growing. Recently, the antineoplastic profiles of milk and whey from Mediterranean buffalo (Bubalus bubalis) have been brought to attention. However, to date, compared to cow milk, the potential health benefits of buffalo milk exosome-miRNA are still little explored. In the present study, we profiled the exosomal miRNA from buffalo milk and investigated the possible anticancer effects in CRC cells, HCT116, and HT-29. Results indicated that buffalo milk exosomes contained higher levels of miR-27b, miR-15b, and miR-148a compared to cow milk. Mimic miR-27b transfection in CRC cells induced higher cytotoxic effects (p < 0.01) compared to miR-15b and miR-148a. Moreover, miR-27b overexpression in HCT116 and HT-29 cells (miR-27b+) induced apoptosis, mitochondrial reactive oxygen species (ROS), and lysosome accumulation. Exposure of miR-27b+ cells to the bioactive 3kDa milk extract aggravated the apoptosis rate (p < 0.01), mitochondrial stress (p < 0.01), and advanced endoplasmic reticulum (ER) stress (p < 0.01), via PERK/IRE1/XBP1 and CHOP protein modulation (p < 0.01). Moreover, GSK2606414, the ER-inhibitor (ER-i), decreased the apoptosis phenomenon and XBP1 and CHOP modulation in miR-27b+ cells treated with milk (p < 0.01 vs. miR-27b++Milk), suggesting the ER stress as a cell-death-aggravating mechanism. These results support the in vitro anticancer activity of 3kDa milk extract and unveil the contribution of miR-27b in the promising beneficial effect of buffalo milk in CRC prevention.

Ruthenium-based antitumor drugs and delivery systems from monotherapy to combination therapy

Ruthenium complex is an important compound group for antitumor drug research and development. NAMI-A, KP1019, TLD1433 and other ruthenium complexes have entered clinical research. In recent years, the research on ruthenium antitumor drugs has not been limited to single chemotherapy drugs; other applications of ruthenium complexes have emerged such as in combination therapy. During the development of ruthenium complexes, drug delivery forms of ruthenium antitumor drugs have also evolved from single-molecule drugs to nanodrug delivery systems. The review summarizes the following aspects: (1) ruthenium complexes from monotherapy to combination therapy, including the development of single-molecule compounds, carrier nanomedicine, and self-assembly of carrier-free nanomedicine; (2) ruthenium complexes in the process of ADME in terms of absorption, distribution, metabolism and excretion; (3) the applications of ruthenium complexes in combination therapy, including photodynamic therapy (PDT), photothermal therapy (PTT), photoactivated chemotherapy (PACT), immunotherapy, and their combined application; (4) the future prospects of ruthenium-based antitumor drugs.

Recent advances in noble metal complex based photodynamic therapy

Photodynamic therapy (PDT) utilizes light-activated photosensitizers (PSs) to generate toxic species for therapeutics. It has become an emerging solution for cancer treatment because of its specific spatiotemporal selectivity and minimal invasiveness. Noble metal (Ru, Ir and Pt) complexes are of increasing interest as photosensitizers for their excellent photophysical, photochemical, and photobiological properties. In this review, we highlight recent advancements in the development of noble metal complex photosensitizers for PDT during the last 5 years. We will summarize the design strategies of noble metal complexes for efficient and precise PDT, including increasing the light penetration depth, reducing the oxygen-dependent nature and improving target ability. Finally, we summarize recent efforts for the development of noble-based PSs and discuss the limitations of such PSs in clinical application and future perspectives in this field, such as the combination of PDT with other treatment modalities.

Systematic evaluation of the antitumor activity of three ruthenium polypyridyl complexes

Ruthenium-containing complexes have emerged as good alternative to the currently used platinum-containing drugs for malignant tumor therapy. In this work, cytotoxic effects of recently synthesized ruthenium polypyridyl complexes [Ru(bpy)₂(CFPIP)](ClO₄)₂ (bpy = 2,2'-bipyridine, CFPIP = (E)-2-(4-fluorostyryl)-1H-imidazo[4,5-f][1,10]phenanthroline, Ru(II)-1), [Ru(phen)₂(CFPIP)](ClO₄)₂ (phen = 1,10-phenanthroline, Ru(II)-2) and [Ru(dmb)₂(CFPIP)](ClO₄)₂ (dmb = 4,4'-dimethyl-2,2'-bipyridine, Ru(II)-3) toward different tumor cells were investigated in vitro and compared with cisplatin, the most widely used chemotherapeutic drug against hepatocellular carcinoma (HepG-2). The results demonstrate that target complexes show excellent cytotoxicity against HepG-2 cells with low IC₅₀ value of 21.4 ± 1.5, 18.0 ± 2.1 and 22.3 ± 1.7 μM, respectively. It was important noting that target Ru(II) complexes exhibited better antitumor activity than cisplatin (IC50 = 28.5 ± 2.4 μM) against HepG-2 cells, and has no obvious toxicity to normal cell LO2. DNA binding results suggest that Ru(II)-1, Ru(II)-2 and Ru(II)-3 interact with CT DNA (calf thymus DNA) through intercalative mode. Complexes exerted its antitumor activity through increasing anti-migration and inducing cell cycle arrest at the S phase. In addition, the apoptosis was tested by AO (acridine orange)/EB (ethidium bromide) staining and flow cytometry. Mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and colocalization tests were also evaluated by ImageXpress Micro XLS system. Overall, the results show that the ruthenium polypyridyl complexes induce apoptosis in HepG-2 cells through ROS-mediated mitochondria dysfunction pathway.

Anti-melanoma effect of ruthenium(II)-diphosphine complexes containing naphthoquinone ligand

The use of natural products as potential ligands has been explored as a strategy in the development of metal-based chemotherapy. Since ruthenium complexes are promising alternatives to traditional antitumor agents, this study evaluated the anti-melanoma potential of two ruthenium(II) complexes containing the naphthoquinone ligands lapachol (lap), [Ru(lap)(dppm)2]PF6, and lawsone (law), [Ru(law)(dppm)2]PF6, in addition to the bis(diphenylphosphino)methane (dppm) ligand, referred to as complexes (1) and (2), respectively, using a syngeneic murine melanoma model. Activation of the apoptotic pathway by the treatments was assessed by immunohistochemistry in tumor tissue. Additionally, toxicity of the treatments was evaluated by variation in body and organ weight, quantification of biochemical indicators of renal damage, and genotoxicity in bone marrow and hepatocytes. First, the antiproliferative activity of (1) and (2) was observed in B16F10 cells, with IC50 values of 2.78 and 1.68 μM, respectively. The results obtained in mice showed that, unlike complex (1), (2) possesses significant anti-melanoma activity demonstrated by a reduction in tumor volume and mass (88.42%), as well as in mitosis frequency (83.86%). Additionally, complex (2) increased the levels of cleaved caspase-3, inducing tumor cell apoptosis. When compared to the metallodrug cisplatin, complex (2) exhibited similar anti-melanoma activity and lower toxicity considering all parameters evaluated. In silico studies demonstrated no difference in the binding energy of the naphthoquinone complex between complexes (1) and (2). However, the complex containing the lawsone ligand has a lower molar volume, which may be important for interactions with minor DNA grooves. The present results demonstrate the antitumor efficiency of complex (2) and a significantly lower systemic toxicity compared to cisplatin.

Exploring the Potential of Aromatherapy as an Adjuvant Therapy in Cancer and its Complications: A Comprehensive Update

BACKGROUND

Aromatherapy is a traditional practice of employing essential oils for the therapeutic purposes, currently headed under the category of complementary and adjuvant medicine.

OBJECTIVE

The aim of this review article is to summarize the potential health benefits of aromatic essential oil from traditional times till the present. It also proposed some mechanisms which can be utilized as basis for using aromatherapy in cancer and cancer linked complications.

METHODS

To find out the relevant and authentic data, several search engines like Science direct, Pubmed, research gate, etc. were thoroughly checked by inserting key words like aromatherapy, complementary, adjuvant therapy etc. to collect the relevant material in context of article. Also, the chemical components of essential oil were classified based on the presence of functional groups, which are further explored for their cytotoxic potential.

RESULTS

The result depicted the anti-cancer potential of chemical constituents of essential oil against different types of cancer. Moreover, the essential oils show promising anti-inflammatory, anti-microbial, anti-oxidant and anti-mutagenic potential in several studies, which collectively can form the basis for initiation of its anti-cancer utility.

CONCLUSION

Aromatherapy can serve as adjuvant economic therapy in cancer after the standardization of protocol.

Development of four ruthenium polypyridyl complexes as antitumor agents: Design, biological evaluation and mechanism investigation

Ruthenium complexes are expected to be new opportunities for the development of antitumor agents. Herein, four ruthenium polypyridyl complexes ([Ru(bpy)₂(CAPIP)](ClO₄)₂ (Ru(II)-1, bpy = 2,2'-bipyridine; CAPIP = (E)-2-(2-(furan-2-yl)vinyl)-1H-imidazo[4,5-f][1,10]phenanthroline), [Ru(phen)₂(CA-PIP)](ClO₄)₂ (Ru(II)-2, phen = 1,10-phenanthroline), [Ru(dmb)₂(CAPIP)](ClO₄)₂ (Ru(II)-3, dmb = 4,4'-dimethyl-2,2'-bipyridine), [Ru(dmb)₂(ETPIP)](ClO₄)₂ (Ru(II)-4, ETPIP = 2-(4-(thiophen-2-ylethynyl)phenyl)-1H-imidazo[4,5-f][1,10]phen-anthroline)) have been investigated as mitochondria-targeted antitumor metallodrugs. DNA binding studies indicated that target Ru(II) complexes interacts with CT DNA (calf thymus DNA) by an intercalative mode. Cytotoxicity assay results demonstrate that Ru(II) complexes show high cytotoxicity against A549 cells with low IC₅₀ value of 23.6 ± 2.3, 20.1 ± 1.9, 22.7 ± 1.8 and 18.4 ± 2.3 μM, respectively. Flow cytometry and morphological analysis revealed that these Ru(II) complexes can induce apoptosis in A549 cells. Intracellular reactive oxygen species (ROS) and mitochondrial membrane potential were also investigated by ImageXpress Micro XLS system. The experimental results indicate that the reactive oxygen species in A549 cells increased significantly and mitochondrial membrane potential decreased obviously. In addition, colocalization studies shown these complexes could get to the cytoplasm through the cell membrane and accumulate in the mitochondria. Furthermore, Ru(II) complexes can effectively induces cell cycle arrest at the S phase in A549 cells. Finally, cell invasion assay and quantitative studies were also performed to investigate the mechanism of this process. All in together, this study suggested that these Ru(II) complexes could induce apoptosis in A549 cells through cell cycle arrest and ROS-mediated mitochondrial dysfunction pathway.

miR-7112-3p targets PERK to regulate the endoplasmic reticulum stress pathway and apoptosis induced by photodynamic therapy in colorectal cancer CX-1 cells

BACKGROUND

Colorectal cancer (CRC) is the third most common malignant tumor worldwide. Photodynamic therapy (PDT) is an emerging modality for the treatment of solid tumors. Sinoporphyrin sodium (DVDMS) is a new photosensitizer with good therapeutic killing effects on cancer cells. Recent findings have shown that microRNAs play important roles in many biological processes. However, the functions of microRNAs in DVDMS-induced PDT remain largely unclear.

MATERIALS AND METHODS

Proteins involved in endoplasmic reticulum (ER) stress and apoptosis of CX-1 cells treated with DVDMS-PDT were examined by Western blotting and cell viability assays. 15 candidate miRNAs targeting RNA-dependent protein kinase-like ER kinase (PERK) were screened and verified using the TargetScan, miRWalk and miRDB databases. The downstream pathways of candidate miRNAs with high scores were studied by cell transfection, qRT-PCR, Western blotting and dual-luciferase reporter assays. The subcellular location of DVDMS was confirmed by laser confocal microscopy.

RESULTS

DVDMS-PDT induced apoptosis via elevated ER stress and activation of the PERK/ATF4/CHOP/caspase cascade pathway in CX-1 cells. The endoplasmic reticulum was involved in the subcellular accumulation of DVDMS in CX-1 cells. Dual-luciferase reporting experiment confirmed that a direct crosslinking between miR-7112-3p and PERK. In addition, miR-7112-3p was highly expressed in CRC tissues compared with peripheral tissues.

CONCLUSION

Our work showed that miR-7112-3p directly targeted PERK and further regulated PERK/ATF4/CHOP/caspase cascade pathway, resulting in enhanced apoptosis in CX-1 cells treated with DVDMS-PDT.

Endoplasmic reticulum stress: an arising target for metal-based anticancer agents

Metal anticancer agents are rapidly emerging as selective, potent therapeutics that exhibit anticancer activity by inducing endoplasmic reticulum stress.

A novel Mn-Cu bimetallic complex for enhanced chemodynamic therapy with simultaneous glutathione depletion

A bimetallic complex, containing Mn(ii) and Cu(ii) moieties, was synthesized for chemodynamic therapy (CDT) of cancer. The complex was capable of generating a hydroxyl radical (˙OH) via a Fenton-like reaction involving a Mn complex, and simultaneously depleting glutathione via a Cu complex induced oxidative reaction, thereby enhancing the efficiency of CDT.

Ru(II)-thymine complex causes DNA damage and apoptotic cell death in human colon carcinoma HCT116 cells mediated by JNK/p38/ERK1/2 via a p53-independent signaling

Ru(II)-thymine complex [Ru(PPh₃)₂(Thy)(bipy)]PF₆ (where PPh₃ = triphenylphosphine, Thy = thyminate and bipy = 2,2′-bipyridine) is a potent cytotoxic agent with ability to bind to DNA, inducing caspase-mediated apoptosis in leukemia cells. In this study, we investigated the mechanism underlying the cell death induction by Ru(II)-thymine complex in human colon carcinoma HCT116 cells, as well as its effect in xenograft tumor model. The Ru(II)-thymine complex increased significantly the percentage of apoptotic HCT116 cells. Co-treatment with a JNK/SAPK inhibitor, p38 MAPK inhibitor and MEK inhibitor, which inhibit the activation of ERK1/2, caused a marked reduction of the percentage of complex-induced apoptotic cells. Moreover, the Ru(II)-thymine complex induced an increase in phospho-JNK2 (T183/Y185), phospho-p38α (T180/Y182) and phospho-ERK1 (T202/Y204) levels in HCT116 cells. Treatment with the Ru(II)-thymine complex increased significantly the phospho-histone H2AX (S139) expression, a DNA damage marker. The expression of phospho-p53 (S15) and MDM2 were not changed, and the co-treatment with a p53 inhibitor (cyclic pifithrin-α) did not reduce the complex-induced apoptosis in HCT116 cells, indicating that the Ru(II)-thymine complex induces DNA damage-mediated apoptosis by JNK/p38/ERK1/2 via a p53-independent signaling. The Ru(II)-thymine complex (1 and 2 mg/kg/day) also inhibited HCT116 cell growth in a xenograft model, reducing the tumor mass at 32.6–40.1%. Altogether, indicate that the Ru(II)-thymine complex is a promising anti-colon cancer drug candidate.

Ruthenium(II) Complexes as Potential Apoptosis Inducers in Cancer Therapy

The compound cis-diamminedichloroplatinum(II) (cisplatin) is the most widely used anticancer drug, but due to its serious side effects (including gastrointestinal symptoms, renal tubular injury, neuromuscular complications, and ototoxicity), clinical applications of cisplatin are limited. Therefore, these limitations have provided an encouragement for further research into other transition metal complexes, with an aim to overcome the disadvantages related with cisplatin therapy. In the search for effective complexes that can be targeted against tumor cells, many research groups synthesized various ruthenium( II) complexes with different ligands. Also, newly synthesized ruthenium(II) complexes showed selective anticancer activity against different types of cancer cells. Activity of ruthenium(II) complexes in some cases was even higher than that of cisplatin against the same cells. Precise mechanism of action of ruthenium(II) complexes is not fully understood. The different examples mentioned in this review showed that ruthenium(II) complexes decreased viability of cancer cells by induction of apoptosis and/or by cell cycle arrest which implies their different mechanism of action against different types of cancer cells.

Endoplasmic reticulum targeted cyclometalated iridium(iii) complexes as efficient photodynamic therapy photosensitizers

A series of ER-targeted cyclometalated Ir(iii) complexes with a gradually extended conjugated area in the main ligand were effective PDT photosensitizers and triggered ER-stress induced apoptosis in cancer cell lines.