Peptidylarginine deiminase 3 modulates response to neratinib in HER2 positive breast cancer.

Neratinib is a tyrosine kinase inhibitor that is used for the therapy of patients with HER2+ breast tumors. However, despite its clinical benefit, resistance to the drug may arise. Here we have created cellular models of neratinib resistance to investigate the mechanisms underlying such resistance. Chronic neratinib exposure of BT474 human HER2+ breast cancer cells resulted in the selection of several clones resistant to the antiproliferative action of the drug. The clones were characterized biochemically and biologically using a variety of techniques. These clones retained HER2 levels similar to parental cells. Knockdown experiments showed that the neratinib-resistant clones retained oncogenic dependence on HER2. Moreover, the tyrosine phosphorylation status of BT474 and the resistant clones was equally sensitive to neratinib. Transcriptomic and Western analyses showed that peptidylarginine deiminase 3 was overexpressed in the three neratinib-resistant clones studied but was undetectable in BT474 cells. Experiments performed in the neratinib-resistant clones showed that reduction of PADI3 or inhibition of its function restored sensitivity to the antiproliferative action of neratinib. Moreover, overexpression of FLAG-tagged PADI3 in BT474 cells provoked resistance to the antiproliferative action of neratinib. Together, these results uncover a role of PADI3 in the regulation of sensitivity to neratinib in breast cancer cells overexpressing HER2 and open the possibility of using PADI3 inhibitors to fight resistance to neratinib.

Multiple mechanisms contribute to acquired TRAIL resistance in multiple myeloma.

Multiple Myeloma (MM) prognosis has recently improved thanks to the incorporation of new therapies to the clinic. Nonetheless, it is still a non-curable malignancy. Targeting cancer cells with agents inducing cell death has been an appealing alternative investigated over the years, as is the case of TRAIL, an agonist of DR4 and DR5 death receptors. This pathway, involved in apoptosis triggering, has demonstrated efficacy on MM cells. In this research, we have investigated the sensitivity of a panel of MM cells to this agent and generated TRAIL-resistant models by continuous culture of sensitive cells with this peptide. Using genomic and biochemical approaches, the mechanisms underlying resistance were investigated. In TRAIL-resistant cells, a strong reduction in cell-surface receptor levels was detected and impaired the apoptotic machinery to respond to the treatment, enabling cells to efficiently form the Death Inducing Signalling Complex. In addition, an upregulation of the inhibitory protein c-FLIP was detected. Even though the manipulation of these proteins was able to modify cellular responses to TRAIL, it was not complete, pointing to other mechanisms involved in TRAIL resistance.

Ocoxin Oral Solution Triggers DNA Damage and Cell Death in Ovarian Cancer.

Ovarian cancer is the most fatal of all the reproductive cancers within the female population, mainly due to its late diagnosis that limits surgery and medical treatment. Classically, ovarian cancer therapy has included conventional chemotherapy, and other therapeutic approaches are now being used to treat these patients, but the outcomes of the disease are still poor. Therefore, new strategies are needed to improve life expectancy and life quality of ovarian cancer patients. Considering that, we investigated the effect of the nutritional supplement Ocoxin Oral Solution (OOS) in ovarian cancer models. OOS contains several nutritional supplements, some of them with demonstrated antitumoral action. In vitro studies showed that OOS inhibited the proliferation of several ovarian cancer cell lines, especially of those representative of the endometrioid subtype, in a time- and dose-dependent manner. A fast cell death induction after OOS treatment was observed, and when the molecular mechanisms leading to this effect were investigated, an activation of the DNA damage checkpoint was detected, as shown by activation (phosphorylation) of CHK1 and CHK2 kinases that was followed by the phosphorylation of the target protein histone H2AX. When tested in animal models of ovarian cancer, OOS reduced tumor growth without any observed secondary effects. Moreover, such reduction in tumor proliferation was caused by the induction of DNA damage as corroborated by the in vivo phosphorylation of CHK2 and Histone H2AX. Finally, OOS potentiated the action of carboplatin or olaparib, the standard of care treatments used in ovarian clinics, opening the possibility of including OOS in combination with those standard of care agents in patients with ovarian cancer.

Trastuzumab deruxtecan in breast cancer.

Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate (ADC) consisting of a humanised, anti-human epidermal growth factor receptor 2 (HER2) monoclonal antibody covalently linked to a topoisomerase I inhibitor cytotoxic payload (DXd). The high drug-to-antibody ratio (8:1) ensures a high DXd concentration is delivered to target tumour cells, following internalisation of T-DXd and subsequent cleavage of its tetrapeptide-based linker. DXd's membrane-permeable nature enables it to cross cell membranes and potentially exert antitumour activity on surrounding tumour cells regardless of HER2 expression. T-DXd's unique mechanism of action is reflected in its efficacy in clinical trials in patients with HER2-positive advanced breast cancer (in heavily pretreated populations and in those previously treated with a taxane and trastuzumab), as well as HER2-low metastatic breast cancer. Thus, ADCs such as T-DXd have the potential to change the treatment paradigm of targeting HER2 in metastatic breast cancer, including eventually within the adjuvant/neoadjuvant setting.

Ocoxin oral solution demonstrates antiviral properties in cellular models.

Ocoxin Oral Solution (OOS) and Viusid (VS) are nutritional supplements that include several natural products which affect different cellular functions, such as proliferation or the redox status. In addition, some of their constituent components have been described to exert an antiviral effect. Considering this, it was hypothesized that treatment with OOS and VS could protect from viral infections. In order to evaluate the impact of OOS and VS on viral infection, lentivirus and retrovirus whose genomes coded for green fluorescent protein were used. In addition, and as a second approach to measure viral infection, a hemagglutinin-tagged form of the mitogen-activated protein kinase ERK5 was also inserted in the retroviral vector. Viral particles produced in 293T cells were used to infect HeLa cells in the presence or absence of OOS or VS. It was observed that VS had a minimal effect on the capacity of either lentivirus or retrovirus to infect HeLa cells. However, OOS significantly reduced the infection of HeLa cells with both of these viruses. The effect was dose-dependent, reaching a maximum at a 1:100 dilution of OOS. These results suggested that, in addition to its well-known antitumoral properties, OOS may also inhibit infection with viruses. This effect is relevant since patients receiving oncological therapies are more susceptible to viral infections, and nutritional supplements such as OOS may help in reducing the severity of these potential pathogenic infections.

Novel ADCs and Strategies to Overcome Resistance to Anti-HER2 ADCs.

During recent years, a number of new compounds against HER2 have reached clinics, improving the prognosis and quality of life of HER2-positive breast cancer patients. Nonetheless, resistance to standard-of-care drugs has motivated the development of novel agents, such as new antibody-drug conjugates (ADCs). The latter are a group of drugs that benefit from the potency of cytotoxic agents whose action is specifically guided to the tumor by the target-specific antibody. Two anti-HER2 ADCs have reached the clinic: trastuzumab-emtansine and, more recently, trastuzumab-deruxtecan. In addition, several other HER2-targeted ADCs are in preclinical or clinical development, some of them with promising signs of activity. In the present review, the structure, mechanism of action, and potential resistance to all these ADCs will be described. Specific attention will be given to discussing novel strategies to circumvent resistance to ADCs.

Antitumoral Properties of the Nutritional Supplement Ocoxin Oral Solution: A Comprehensive Review.

Ocoxin Oral Solution (OOS) is a nutritional supplement whose formulation includes several plant extracts and natural products with demonstrated antitumoral properties. This review summarizes the antitumoral action of the different constituents of OOS. The action of this formulation on different preclinical models as well as clinical trials is reviewed, paying special attention to the mechanism of action and quality of life improvement properties of this nutritional supplement. Molecularly, its mode of action includes a double edge role on tumor biology, that involves a slowdown in cell proliferation accompanied by cell death induction. Given the safety and good tolerability of OOS, and its potentiation of the antitumoral effect of other standard of care drugs, OOS may be used in the oncology clinic in combination with conventional therapies.

Continuous endoglin (CD105) overexpression disrupts angiogenesis and facilitates tumor cell metastasis.

Endoglin (CD105) is an auxiliary receptor for members of the TFG-ß superfamily. Whereas it has been demonstrated that the deficiency of endoglin leads to minor and defective angiogenesis, little is known about the effect of its increased expression, characteristic of several types of cancer. Angiogenesis is essential for tumor growth, so high levels of proangiogenic molecules, such as endoglin, are supposed to be related to greater tumor growth leading to a poor cancer prognosis. However, we demonstrate here that endoglin overexpression do not stimulate sprouting or vascularization in several in vitro and in vivo models. Instead, steady endoglin overexpression keep endothelial cells in an active phenotype that results in an impairment of the correct stabilization of the endothelium and the recruitment of mural cells. In a context of continuous enhanced angiogenesis, such as in tumors, endoglin overexpression gives rise to altered vessels with an incomplete mural coverage that permit the extravasation of blood. Moreover, these alterations allow the intravasation of tumor cells, the subsequent development of metastases and, thus, a worse cancer prognosis.

Adaptive resistance to trastuzumab impairs response to neratinib and lapatinib through deregulation of cell death mechanisms.

Small molecule inhibitors (TKIs) of HER2 have demonstrated clinical benefit in HER2-positive breast tumors. One of them, lapatinib, is used once advanced tumors become refractory to the HER2 antibody trastuzumab. Another one, neratinib, has shown benefit in high-risk early-stage breast cancer after trastuzumab-based therapies. A common characteristic is that patients are formerly treated with trastuzumab. We have explored whether trastuzumab previous therapy affects its antitumoral action. Long time exposure of the HER2+ cell line BT474 to trastuzumab resulted in trastuzumab-insensitive cells (BTRH cells). While treatment of wild type BT474 cells with lapatinib or neratinib resulted in decreased viability, BTRH cells were resistant to the action of these TKIs. Analogous results were obtained using trastuzumab-resistant cells derived from a PDX. Functional transcriptomic analyses and biochemical studies demonstrated that the TKIs caused DNA damage and apoptosis in wild type cells, but not in BTRH. Moreover, previous treatment with trastuzumab impairs response to small TKIs, by eliminating their proapoptotic action. Moreover, actioning on the apoptotic machinery using a chemical library of proapoptotic compounds led to the identification of clinical-stage drugs that may be used to fight trastuzumab-TKI resistance.

Central Role of Cell Cycle Regulation in the Antitumoral Action of Ocoxin.

Nutritional supplements which include natural antitumoral compounds could represent safe and efficient additives for cancer patients. One such nutritional supplement, Ocoxin Oral solution (OOS), is a composite formulation that contains several antioxidants and exhibits antitumoral properties in several in vitro and in vivo tumor conditions. Here, we performed a functional genomic analysis to uncover the mechanism of the antitumoral action of OOS. Using in vivo models of acute myelogenous leukemia (AML, HEL cells, representative of a liquid tumor) and small-cell lung cancer (GLC-8, representative of a solid tumor), we showed that OOS treatment altered the transcriptome of xenografted tumors created by subcutaneously implanting these cells. Functional transcriptomic studies pointed to a cell cycle deregulation after OOS treatment. The main pathway responsible for this deregulation was the E2F-TFDP route, which was affected at different points. The alterations ultimately led to a decrease in pathway activation. Moreover, when OOS-deregulated genes in the AML context were analyzed in patient samples, a clear correlation with their levels and prognosis was observed. Together, these data led us to suggest that the antitumoral effect of OOS is due to blockade of cell cycle progression mainly caused by the action of OOS on the E2F-TFDP pathway.

TRAIL receptor activation overcomes resistance to trastuzumab in HER2 positive breast cancer cells.

The appearance of resistance to the anti-HER2 targeted drug trastuzumab constitutes, nowadays, an important challenge in the oncology clinic. To fight such resistance, we searched for potential vulnerabilities in cells resistant to that drug. To that end, we used cell lines primary resistant to trastuzumab, as well as cells made secondarily resistant to the drug upon continuous exposure. Using genomic and proteomic approaches, a deregulation in cell death pathways was identified in trastuzumab-resistant cells. More precisely, an increased response to the death factor TRAIL, caused by an increase in the cellular receptors for this factor, was observed. In parallel, a decrease in inhibitory components of the pathway was detected. This combination produces a more efficient assembly of the functional complex in the trastuzumab-resistant cells that translates in the observed increased response to TRAIL. Analysis of HER2 positive patient samples confirmed deregulation of this pathway in trastuzumab-resistant patients. Taken together our data identify a vulnerability of trastuzumab-resistant cells that could be used to design new targeted therapies in that context.

Antitumoral effect of Ocoxin, a natural compound-containing nutritional supplement, in small cell lung cancer.

Lung cancer is the most frequently diagnosed neoplasia and represents the leading cause of cancer-related deaths worldwide. Due to this fact, efforts to improve patient survival through the introduction of novel therapies, as well as preventive actions, are urgently required. Considering this scenario, the antitumoral action of the composite formulation Ocoxin® oral solution (OOS), that contains several antitumoral compounds including antioxidants, was tested in small cell lung cancer (SCLC) in vitro and in vivo preclinical models. OOS exhibited anti-SCLC action that was both time and dose dependent. In vivo OOS decreased the growth of tumors implanted in mice without showing signs of toxicity. The antitumoral effect was due to inhibition of cell proliferation and increased cell death. Genomic and biochemical analyses indicated that OOS augmented p27 and decreased the functioning of several routes involved in cell proliferation. In addition, OOS caused cell death by activation of caspases. Importantly, OOS favored the action of several standard of care drugs used in the SCLC clinic. Our results suggest that OOS has antitumoral action on SCLC, and could be used to supplement the action of drugs commonly used to treat this type of tumor.

The kinesin spindle protein inhibitor filanesib enhances the activity of pomalidomide and dexamethasone in multiple myeloma.

Kinesin spindle protein inhibition is known to be an effective therapeutic approach in several malignancies. Filanesib (ARRY-520), an inhibitor of this protein, has demonstrated activity in heavily pre-treated multiple myeloma patients. The aim of the work herein was to investigate the activity of filanesib in combination with pomalidomide plus dexamethasone backbone, and the mechanisms underlying the potential synergistic effect. The ability of filanesib to enhance the activity of pomalidomide plus dexamethasone was studied in several in vitro and in vivo models. Mechanisms of this synergistic combination were dissected by gene expression profiling, immunostaining, cell cycle and short interfering ribonucleic acid studies. Filanesib showed in vitro, ex vivo, and in vivo synergy with pomalidomide plus dexamethasone treatment. Importantly, the in vivo synergy observed in this combination was more evident in large, highly proliferative tumors, and was shown to be mediated by the impairment of mitosis transcriptional control, an increase in monopolar spindles, cell cycle arrest and the induction of apoptosis in cells in proliferative phases. In addition, the triple combination increased the activation of the proapoptotic protein BAX, which has previously been associated with sensitivity to filanesib, and could potentially be used as a predictive biomarker of response to this combination. Our results provide preclinical evidence for the potential benefit of the combination of filanesib with pomalidomide and dexamethasone, and supported the initiation of a recently activated trial being conducted by the Spanish Myeloma group which is investigating this combination in relapsed myeloma patients.

Antitumoral effect of Ocoxin in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is becoming one of the most prevalent types of cancer worldwide. The most efficient types of treatment at present include surgical resection and liver transplantation, but these treatments may only be used in a small percentage of patients. In order to identify novel therapeutic strategies for this disease, the present study explored the potential antitumoral effect of Ocoxin® oral solution (OOS) in HCC. OOS inhibited the proliferation of HCC cell lines in a time- and dose-dependent manner, being more efficient when used in combination with sorafenib, a standard of care treatment for patients diagnosed with advanced-stage disease. Mechanistic studies indicated that the effect of OOS was due to the induction of cell cycle arrest rather than the stimulation of apoptotic cell death. The cell cycle was slowed down in all phases in the HCC cell lines treated with OOS. Finally, when tested in animal models of HCC, OOS reduced tumor progression through the induction of necrosis in xenograft tumor models. Considering the poor prognosis and high resistance to antitumor treatments of HCC, the antiproliferative action of OOS, particularly in combination with sorafenib, provides the opportunity to investigate the effect of combined therapy in a clinical setting.

Resistance to the Antibody-Drug Conjugate T-DM1 Is Based in a Reduction in Lysosomal Proteolytic Activity.

Trastuzumab-emtansine (T-DM1) is an antibody-drug conjugate (ADC) that was approved recently to treat HER2+ breast cancers. Despite its impressive clinical efficacy in many patients, intrinsic and acquired resistance to T-DM1 has emerged as a challenge. To identify mechanisms of T-DM1 resistance, we isolated several resistant HER2+ clones exhibiting stable drug refractoriness in vitro and in vivo Genomic comparisons showed substantial differences among three of the isolated clones, indicating several potential mechanisms of resistance to T-DM1. However, we observed no differences in HER2 levels and signaling among the resistant models and parental HER2+ cells. Bioinformatics studies suggested that intracellular trafficking of T-DM1 could underlie resistance to T-DM1, and systematic analysis of the path followed by T-DM1 showed that the early steps in the internalization of the drug were unaltered. However, in some of the resistant clones, T-DM1 accumulated in lysosomes. In these clones, lysosomal pH was increased and the proteolytic activity of these organelles was deranged. These results were confirmed in T-DM1-resistant cells from patient-derived HER2+ samples. We postulate that resistance to T-DM1 occurs through multiple mechanisms, one of which is impaired lysosomal proteolytic activity. Because other ADC may use the same internalization-degradation pathway to deliver active payloads, strategies aimed at restoring lysosomal functionality might overcome resistance to ADC-based therapies and improve their effectiveness. Cancer Res; 77(17); 4639-51. ©2017 AACR.

Antitumoral effect of Ocoxin on acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy whose incidence is growing in developed countries. In the relapse setting, very limited therapeutic options are available and in most cases only palliative care can be offered to patients. The effect of a composite formulation that contains several antioxidants, Ocoxin Oral solution (OOS), was tested in this condition. When analyzed in vitro, OOS exhibited anti-AML action that was both time and dose dependent. In vivo OOS induced a ralentization of tumor growth that was due to a decrease in cell proliferation. Such effect could, at least partially, be due to an increase in the cell cycle inhibitor p27, although other cell cycle proteins seemed to be altered. Besides, OOS induced an immunomodulatory effect through the induction of IL6. When tested in combination with other therapeutic agents normally used in the treatment of AML patients, OOS demonstrated a higher antiproliferative action, suggesting that it may be used in combination with those standard of care treatments to potentiate their antiproliferative action in the AML clinic.

Modulation of cereblon levels by anti-myeloma agents.

The use of thalidomide derivatives (IMIDs) has improved multiple myeloma prognosis, through an unknown mechanism of action. Recently one molecular target, the cereblon (CRBN) protein, has been identified. CRBN acts by binding to DDB1-CUL4-ROC1 forming a ubiquitin ligase multiprotein complex. We have generated antibodies to different regions of CRBN protein, and analyzed the biological consequences of augmenting or decreasing CRBN levels. CRBN was expressed in all the myeloma cell lines tested, independently of their sensitivity to IMIDs, and the CRBN-DDB1-CUL4 complex was efficiently formed. At the molecular level, long-term treatment with IMIDs induced a slight decrease in CRBN levels and a reduction in the CRBN-DDB1-CUL4 complex. Interestingly, treatment with other anti-myeloma drugs downregulated cellular contents of CRBN, and in a much faster fashion. These results suggest that CRBN is an important mediator of the cellular response to IMIDs, but also critical in the maintenance of cell viability and/or proliferation.

Transcriptomic profile induced in bone marrow mesenchymal stromal cells after interaction with multiple myeloma cells: implications in myeloma progression and myeloma bone disease.

Despite evidence about the implication of the bone marrow (BM) stromal microenvironment in multiple myeloma (MM) cell growth and survival, little is known about the effects of myelomatous cells on BM stromal cells. Mesenchymal stromal cells (MSCs) from healthy donors (dMSCs) or myeloma patients (pMSCs) were co-cultured with the myeloma cell line MM.1S, and the transcriptomic profile of MSCs induced by this interaction was analyzed. Deregulated genes after co-culture common to both d/pMSCs revealed functional involvement in tumor microenvironment cross-talk, myeloma growth induction and drug resistance, angiogenesis and signals for osteoclast activation and osteoblast inhibition. Additional genes induced by co-culture were exclusively deregulated in pMSCs and predominantly associated to RNA processing, the ubiquitine-proteasome pathway, cell cycle regulation, cellular stress and non-canonical Wnt signaling. The upregulated expression of five genes after co-culture (CXCL1, CXCL5 and CXCL6 in d/pMSCs, and Neuregulin 3 and Norrie disease protein exclusively in pMSCs) was confirmed, and functional in vitro assays revealed putative roles in MM pathophysiology. The transcriptomic profile of pMSCs co-cultured with myeloma cells may better reflect that of MSCs in the BM of myeloma patients, and provides new molecular insights to the contribution of these cells to MM pathophysiology and to myeloma bone disease.

Genetic and pharmacologic evidence that mTOR targeting outweighs mTORC1 inhibition as an antimyeloma strategy.

The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates cell growth, proliferation, metabolism, and cell survival, and plays those roles by forming two functionally distinct multiprotein complexes: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Deregulation of the mTOR pathway has been found in different cancers, including multiple myeloma. Agents acting on mTORC1, such as rapamycin and derivatives, are being explored as antitumoral strategies. However, whether targeting mTOR would be a more effective antimyeloma strategy than exclusively acting on the mTORC1 branch remains to be established. In this report, we explored the activation status of mTOR routes in malignant plasma cells, and analyzed the contribution of mTOR and its two signaling branches to the proliferation of myeloma cells. Gene expression profiling demonstrated deregulation of mTOR pathway-related genes in myeloma plasma cells from patients. Activation of the mTOR pathway in myelomatous plasma cells was corroborated by flow cytometric analyses. RNA interference (RNAi) experiments indicated that mTORC1 predominated over mTORC2 in the control of myeloma cell proliferation. However, mTOR knockdown had a superior antiproliferative effect than acting only on mTORC1 or mTORC2. Pharmacologic studies corroborated that the neutralization of mTOR has a stronger antimyeloma effect than the individual inhibition of mTORC1 or mTORC2. Together, our data support the clinical development of agents that widely target mTOR, instead of agents, such as rapamycin or its derivatives, that solely act on mTORC1.

Deficient spindle assembly checkpoint in multiple myeloma.

Multiple myeloma (MM) is a hematological disease characterized by an abnormal accumulation of plasma cells in the bone marrow. These cells have frequent cytogenetic abnormalities including translocations of the immunoglobulin heavy chain gene and chromosomal gains and losses. In fact, a singular characteristic differentiating MM from other hematological malignancies is the presence of a high degree of aneuploidies. As chromosomal abnormalities can be generated by alterations in the spindle assembly checkpoint (SAC), the functionality of such checkpoint was tested in MM. When SAC components were analyzed in MM cell lines, the RNA levels of most of them were conserved. Nevertheless, the protein content of some key constituents was very low in several cell lines, as was the case of MAD2 or CDC20 in RPMI-8226 or RPMI-LR5 cells. The recovery of their cellular content did not substantially affect cell growth, but improved their ability to segregate chromosomes. Finally, SAC functionality was tested by challenging cells with agents disrupting microtubule dynamics. Most of the cell lines analyzed exhibited functional defects in this checkpoint. Based on the data obtained, alterations both in SAC components and their functionality have been detected in MM, pointing to this pathway as a potential target in MM treatment.