Synthesis of Dipyridylaminoperylenediimide-Metal Complexes and Their Cytotoxicity Studies

A new family of perylenediimide (PDI) silver and copper complexes has been successfully synthesized by reacting ortho- and bay-substituted (dipyrid-2',2″-ylamino)perylenediimide ligands with metal phosphine fragments. The coordination of the metal center did not reveal a significant effect on the photophysical properties, which are mainly due to the PDI ligands, and in some cases quenching of the luminescence was observed. The antiproliferative effect of the free perylenediimide ligands and the metalloPDI complexes against the cervix cancer cell line HeLa was determined by MTT assay. The free perylenediimide ligands exhibited a moderate cytotoxic activity, but the coordination of silver or copper to the dypyridylamino fragment greatly enhanced the activity, suggesting a synergistic effect between the two fragments. In attempts to elucidate the cellular biodistribution of the PDIs and the complexes, a colocalization experiment using specific dyes for the lysosomes or mitochondria as internal standards revealed a major internalization inside the cell for the metal complexes, as well as a partial mitochondrial localization.

Tunable Emissive Ir(III) Benzimidazole-quinoline Hybrids as Promising Theranostic Lead Compounds

Bioactive and luminescent cyclometallated Ir(III) complexes [Ir(ppy)₂ L1]Cl (1) and [Ir(ppy)₂ L2]Cl (2) containing a benzimidazole derivative (L1/L2) as auxiliary mimic of a nucleotide have been synthesised. The emissive properties of both complexes are conditioned by the nature of L1 and L2, rendering an orange and a green emitter respectively. Both are highly emissive with quantum yield increasing in absence of oxygen up to 0.26 (1) and 0.36 (2), suggesting their phosphorescent character. Antiproliferative activity against lung cancer A549 cells increased up to 15 times upon irradiation conditions, reaching IC₅₀ values in the nanomolar range (0.3±0.09 μM (1) and 0.26±0.14 μM (2)) and pointing them as good PSs candidates for photodynamic therapy via ¹ O₂ generation. Cellular biodistribution analysis by fluorescence microscopy suggest the lysosomes as the preferential accumulation organelle. Time-resolved studies showed a greatly increased cellular emission lifetime compared to the solution values, indicating binding to macromolecules or cellular structures and restriction of collision and vibrational quenching.

Multifunctional Heterometallic IrIII -AuI Probes as Promising Anticancer and Antiangiogenic Agents

A new class of emissive cyclometallated IrIII -AuI complexes with a bis(diphenylphosphino) methanide bridging ligand was successfully synthesised from the diphosphino complex [Ir(N^C)2 (dppm)]+ (1). The different gold ancillary ligand, a triphenylphosphine (2), a chloride (3) or a thiocytosine (4) did not reveal any significant effect on the photophysical properties, which are mainly due to metal-to-ligand charge-transfer (3 MLCT) transitions based on IrIII . However, the AuI fragment, along with the ancillary ligand, seemed crucial for the bioactivity in A549 lung carcinoma cells versus endothelial cells. Both cell types display variable sensitivities to the complexes (IC50 =0.6-3.5 μM). The apoptotic pathway is activated in all cases, and paraptotic cell death seems to take place at initial stages in A549 cells. Species 2-4 showed at least dual lysosomal and mitochondrial biodistribution in A549 cells, with an initial lysosomal localisation and a possible trafficking process between both organelles with time. The bimetallic IrIII -AuI complexes disrupted the mitochondrial transmembrane potential in A549 cells and increased reactive oxygen species (ROS) generation and thioredoxin reductase (TrxR) inhibition in comparison with that displayed by the monometallic complex 1. Angiogenic activity assays performed in endothelial cells revealed the promising antimetastatic potential of 1, 2 and 4.

Theranostics Through the Synergistic Cooperation of Heterometallic Complexes

Heterometallic drugs are emerging as a great alternative to conventional metallodrugs. Careful selection of different metallic fragments makes possible to enhance not only the therapeutic potential by a synergistic effect, but also to incorpore key features like traceability. Drugs that integrate traceability and therapy in one system are known as theranostic agents. In cancer research, theranostic agents are becoming increasingly important. They deliver crucial information regarding their biological interplay that can ultimately be used for optimization. The well-established therapeutic potential of Pt^II -, Ru^II - and Au^I -based drugs combined with the outstanding optical properties of d⁶ transition metal complexes grant the delivery of traceable metallodrugs. These species can be easily fine-tuned through modification of their respective ligands to provide a new generation of drugs.

Luminescent Re(I)/Au(I) Species As Selective Anticancer Agents for HeLa Cells

A series of neutral and cationic heterotrimetallic complexes of the type fac-[Re(CO)₃(bipy(CC)₂-(AuL)₂)X]ⁿ, where bipy(CC)₂ is 4,4'-alkynyl-2,2'-bipyridine; L is either triphenylphosphine (PPh₃), [1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene] (IPr), or tert-butyl isocyanide (CN^tBu); and X is a chloride (n = 0) or acetonitrile (n = 1), were synthesized and characterized together with their Re(I) precursors, i.e., fac-[Re(CO)₃(bipy(CC)₂)X]ⁿ. X-ray diffraction of complexes 1, 3, and 6 corroborated the expected octahedral and linear distribution of the ligands along the Re(I) and Au(I) centers, respectively. Luminescent studies showed that all the complexes displayed a broad emission band centered between 565 and 680 nm, corresponding to a ³MLCT from the Re(I) to the diimine derivative. The presence of the gold fragment coordinated to the diimine ligand shifted in all cases the emission maxima toward higher energies. Such an emission difference could be potentially used for assessing the precise moment of interaction of the probe with the biological target if the gold fragment is implicated. Antiproliferative studies in cancer cells, A549 (lung cancer) and HeLa (cervix cancer), showed a generalized selectivity toward HeLa cells for those heterotrimetallic species incubated at longer times (72 vs 24 h). ICP-MS spectrometry revealed the greater cell internalization of cationic vs neutral species. Preliminary fluorescence microscopy experiments showed a different behavior of the complexes in HeLa and A549 cell lines. Whereas the complexes in A549 were randomly distributed in the outside of the cell, those incubated with HeLa cells were located close to the cellular membrane, suggesting some type of interaction, and possibly explaining their cellular selectivity when it comes to the antiproliferative activity displayed in the different cell lines.

Id-1B, an alternatively spliced isoform of the inhibitor of differentiation-1, impairs cancer cell malignancy through inhibition of proliferation and angiogenesis

Id-1 is a member of the helix-loop-helix family of proteins that regulates the activity of transcription factors to suppress cellular differentiation and to promote cell growth. Overexpression of Id-1 in tumor cells correlates with increased malignancy and resistance to chemotherapy and radiotherapy. Id-1B is an isoform generated by alternative splicing that differs from the classical Id-1 in the 13-C-terminal amino acids, whose function is at present unknown. We have studied the role of Id-1B in cancer and its expression in healthy/malignant lung tissues. Overexpression of Id-1B in A549 lung and PC3 prostate cancer cells reduced anchorage-dependent and independent proliferation and clonogenic potential. Moreover, it increased the proportion of cells in the G0/G1 phase of the cell cycle and p27 levels, while reduced phospho-Erk and cyclin A levels. Through microarray analysis, we identified genes involved in cell growth and proliferation that are specifically deregulated as a consequence of Id-1B overexpression, including IGF2, BMP4, Id2, GATA3, EREG and AREG. Id-1B overexpressing cells that were treated with 4Gy irradiation dose were significantly less resistant to cell death. In vivo assays demonstrated that tumors with high Id-1B levels exhibited less growth (p<0.01), metabolic activity (glucose uptake) and angiogenesis (p<0.05) compared to tumors with low Id-1B expression; mice survival was significantly extended (p<0.05). Quantification by qRT-PCR revealed that expression of Id-1B was significantly lower (p<0.01) in human lung tumors compared to their matched nonmalignant counterparts. In conclusion, our results demonstrate that Id-1B decreases the malignancy of lung and prostate cancer cells, sensitizes them to radiotherapy-induced cell death, and counteracts the protumorigenic role of the classical form of Id-1.

TMPRSS4 regulates levels of integrin α5 in NSCLC through miR-205 activity to promote metastasis

Background:

TMPRSS4 is a membrane-anchored protease involved in cell migration and invasion in different cancer types including lung cancer. TMPRSS4 expression is increased in NSCLC and its inhibition through shRNA reduces lung metastasis. However, molecular mechanisms leading to the protumorigenic regulation of TMPRSS4 in lung cancer are unknown.

Methods:

miR-205 was identified as an overexpressed gene upon TMPRSS4 downregulation through microarray analysis. Cell migration and invasion assays and in vivo lung primary tumour and metastasis models were used for functional analysis of miR-205 overexpression in H2170 and H441 cell lines. Luciferase assays were used to identify a new miR-205 direct target in NSCLC.

Results:

miR-205 overexpression promoted an epithelial phenotype with increased E-cadherin and reduced fibronectin. Furthermore, miR-205 expression caused a G₀/G₁ cell cycle arrest and inhibition of cell growth, migration, attachment to fibronectin, primary tumour growth and metastasis formation in vivo. Integrin α5 (a proinvasive protein) was identified as a new miR-205 direct target in NSCLC. Integrin α5 downregulation in lung cancer cells resulted in complete abrogation of cell migration, a decreased capacity to adhere to fibronectin and reduced in vivo tumour growth, compared with control cells. TMPRSS4 silencing resulted in a concomitant reduction of integrin α5 levels.

Conclusion:

We have demonstrated for the first time a new molecular pathway that connects TMPRSS4 and integrin α5 through miR-205 to regulate cancer cell invasion and metastasis. Our results will help designing new therapeutic strategies to inhibit this novel pathway in NSCLC.

The quinoline imidoselenocarbamate EI201 blocks the AKT/mTOR pathway and targets cancer stem cells leading to a strong antitumor activity

Methylimidoselenocarbamates have previously proven to display potent antitumor activities. In the present study we show that these compounds act as multikinase inhibitors. We found that the most effective compound, quinoline imidoselenocarbamate EI201, inhibits the PI3K/AKT/mTOR pathway, which is persistently activated and contributes to malignant progression in various cancers. EI201 blocked the phosphorylation of AKT, mTOR and several of its downstream regulators (p70S6K and 4E-BP1) and ERK1/2 in PC-3, HT-29 and MCF-7 cells in vitro, inducing both autophagy and apoptosis. EI201 also contributes to the loss of maintenance of the selfrenewal and tumorigenic capacity of cancer stem cells (CSCs). 0.1 μmol/L EI201 triggered a reduction in size and number of tumorspheres in PC-3, HT-29 and MCF-7 cells and 4 μmol/L induced the elimination of almost all the tumorspheres in the three studied cell lines. In addition, EI201 suppressed almost 80% prostate tumor growth in vivo (p < 0.01) compared to controls at a relatively low dose (10 mg/kg) in a mouse xenograft model. There was a significant decrease in the subcutaneous primary tumor [18F]-FDG uptake (76.5% reduction, p < 0.05) and in the total tumor burden (76.8% reduction, p < 0.05) after EI201 treatment compared to vehicle control, without causing toxicity in mice. Taken together, our results support further development of EI201 as a novel multi-kinase inhibitor that may be useful against cancers with aberrant upregulation of PI3K/AKT and MAPK signaling pathways.

Use of an inhibitor of differentiation-1 (Id1) expression (exp) to discriminate good prognosis (GP) from poor prognosis (PP) prostate cancer (PCa)

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Background: In the PSA era a significant proportion of PCa patients (pts) at onset have potential indolent tumors that will not impact their life expectancy or quality of life. Most of them will be radically treated and suffer its consequences. Thus, PCa overtreatment is a great concern among clinicians. Pre-treatment molecular factors may help differentiate indolent from aggressive PCa. Id1, involved in cell differentiation and angiogenesis, has recently showed to mediate lung metastasis (mts) from breast cancer. Its role in PCa endothelial (end) cells is well established but its exp and role in PCa cells is controversial. Using a new monoclonal antibody (MoAb) (195–14) for immunohistochemistry (IHC), Id1 exp is limited to some PP breast and bladder tumors. Whether Id1 exp is relevant in PCa prognosis is unknown. We tested 195–14 in PP and GP PCa samples and matched mts where available. Methods: 52 PCa pts were studied, 20 GP + 32 PP. All formalin-fixed and paraffin-embedded primary biopsies and matched mts of 16 of them were stained for tumor and end cell Id1 exp. 195–14 (1:500), (Biocheck), was used for IHC. Results: GP group: median age 65, all pts T2N0M0, median Gleason score 6 (6–9), median PSA at onset 5,5 ng/ml. After a median follow-up of 38 months (ms) 1 pt showed radiological and PSA progression (P); other PSA P. All but one remain alive. PP group: median age was 70, T3-T4 (70%), Gleason 8–10 (61%), median PSA at onset 58 ng/ml, 2 or more mts locations (79%), 94% showed P to docetaxel, median time-to- progression and overall survival after chemotherapy were 18 weeks and 7 ms. Among PP, 39% of primary PCa and 38% of mts showed Id1 tumor cell exp and 79% of primary tumors and 81% of mts showed end Id1 exp. In the GP group 0% showed Id1 tumor cell exp, and 50% showed end Id1 exp. The unexpected Id1 exp difference in tumor cells in PP compared to GP pts predicted clinical outcome. Consistently with other reports end Id1 exp is high in both groups. PP showed higher levels. Conclusions: Id1 exp discriminated GP from PP in our PCa cohort. These novel results highlight Id1 as a prognostic marker in PCa. Whether Id1 exp in the diagnostic biopsy can impact PCa therapeutic decision-making needs further investigation.

No significant financial relationships to disclose.

Inhibitor of differentiation-1 (Id1) characterization in poor-prognosis (PP) human bladder cancer (BCa) primary tumors and matched metastases (MTS) using a new monoclonal antibody (MoAb)

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Background: Id1, involved in cell differentiation, proliferation, tumor angiogenesis and metastasis, has recently showed to mediate lung MTS from breast cancer (PNAS 2007). The expression of Id1 in human cancer has been related to poor prognosis breast, prostate (Gil-Bazo, Amer Soc Clin Oncol GU. 2009) and other non-adenocarcinoma tumors. To date one study showed remarkable Id1 expression (exp.) in 28% of unselected human BCa using a new MoAb (195–14) for immunohistochemistry (IHC) analysis. Our aim is to study Id1 exp. in a group of PP BCa and their matched MTS using this MoAb (195–14). Methods: We selected 22 patients (pts) treated in our institution. Formalin-fixed and paraffin- embedded bladder biopsy samples of each patient and matched MTS samples of 9 of them were stained and scored for tumor and endothelial Id1 exp. Anti-human Id1 rabbit MoAb 195–14 (1:500), (Biocheck), was used for IHC. Results: 90% of pts were males; median age was 61. Most pts had PP advanced (22,7 % stage III; 68,2% stage IV) BCa. Primary tumor samples and additional 9 matched MTS biopsy samples were analyzed. In contrast with the previous data 80% of primary invasive BCa and more than 75% of MTS showed tumor cell Id1 exp. As previously reported Id1 exp. in tumor samples endothelial cells reached 70%. We also observed Id1 exp. in tumor in situ areas near the invasive carcinoma in 16 out of 20 pts expressing Id1 in the primary tumor. Conclusions: For the first time using a MoAb against Id1 and in accord with our previous observations in prostate cancer the selection of PP pts increases tumor cell Id1 exp. from 28 up to 80%. Interestingly we show BCa MTS to express Id1 with a similar exp. pattern than primary tumors. Id1 exp. profile in PP and metastatic initiation of BCa needs further research. Id1 exp. in tumor in situ areas suggests Id1 as an initial factor in the BCa carcinogenic process and in the case of being confirmed Id1 could represent a target in BCa prophylaxis.

No significant financial relationships to disclose.