The number of clinical protocols testing combined therapies including immune check-point inhibitors and platinum salts is currently increasing in lung cancer treatment, however preclinical studies ...and rationale are often lacking. Here, we evaluated the impact of cisplatin treatment on PD-L1 expression analyzing the clinicopathological characteristics of patients who received cisplatin-based neoadjuvant chemotherapy followed by surgery and showed that cisplatin-based induction treatment significantly increased PD-L1 staining in both tumor and immune cells from the microenvironment. Twenty-two patients exhibited positive PD-L1 staining variation after neoadjuvant chemotherapy; including 9 (23.1%) patients switching from <50% to ≥50% of stained tumor-cells. We also confirmed the up-regulation of PD-L1 by cisplatin, at both RNA and protein levels, in nude and immunocompetent mice bearing tumors grafted with A549, LNM-R, or LLC1 lung cancer cell lines. The combined administration of anti-PD-L1 antibodies (3 mg/kg) and cisplatin (1 mg/kg) to mice harboring lung carcinoma significantly reduced tumor growth compared to single agent treatments and controls. Overall, these results suggest that cisplatin treatment could synergize with PD-1/PD-L1 blockade to increase the clinical response, in particular through early and sustainable enhancement of PD-L1 expression.
•Cisplatin-based induction chemotherapy increases PD-L1 expression by tumor cells.•PD-L1 staining of microenvironment immune cells was higher after neoadjuvant treatment.•Cisplatin rapidly increases PD-L1 mRNA and protein levels in lung cancer cell lines.•In tumor bearing mice injection of cisplatin significantly enhances PD-L1 expression.•The combined treatment associating cisplatin and anti-PD-L1 improves tumor response.
Telomerase plays a critical role in stem cell function and tissue regeneration that depends on its ability to elongate telomeres. For nearly two decades, it turned out that TERT regulates a broad ...spectrum of functions including signal transduction, gene expression regulation, and protection against oxidative damage that are independent of its telomere elongation activity. These conclusions that were mainly obtained in cell lines overexpressing telomerase were further strengthened by
models of ectopic expression of telomerase or models of G1
knockout mice without detectable telomere dysfunction. However, the later models were questioned due to the presence of aberrantly shortened telomere in the germline of the parents
that were used to create the G1
mice. The physiological relevance of the functions associated with overexpressed telomerase raised also some concerns due to artifactual situations and localizations and complications to quantify the level of TERT. Another concern with non-canonical functions of TERT was the difficulty to separate a direct TERT-related function from secondary effects. Despite these concerns, more and more evidence accumulates for non-canonical roles of telomerase that are non-obligatory extra-telomeric. Here, we review these non-canonical roles of the TERT subunit of telomerase. Also, we emphasize recent results that link TERT to mitochondria and protection to reactive oxygen species suggesting a protective role of TERT in neurons. Throughout this review, we dissect some controversies regarding the non-canonical functions of telomerase and provide some insights to explain these discrepancies. Finally, we discuss the importance of understanding these alternative functions of telomerase for the development of anticancer strategies.
Breast cancer is the most common cancer in women worldwide. Minimally invasive percutaneous image-guided biopsies are the current cornerstone in the diagnosis of breast lesions detected on ...mammography/ultrasonography/MRI or palpable clinically. However, apparently benign breast disease seen on benign biopsies is a limiting factor for diagnosis and a risk factor of breast cancer especially in the high-risk category patients. Hypothesizing that molecular changes often occur before morphological variations, the levels of the LncRNA H19 were measured in anonymous tissues obtained from 79 women's image guided breast biopsies, and correlated with cancer progression and aggressiveness. Using a double-blinded approach, H19 might be attributed an interesting role of a more sensitive biomarker in core breast biopsies, independently of the radiological/clinical classification and distant from the clinical management. We established different thresholds for H19 levels in normal versus proliferative, versus malignant tissues. Additionnally, H19 could act as an intra-group risk marker categorizing the biopsies in normal versus benign, versus precancerous breast tissue, and as a prognostic factor in cancerous lesions discriminating aggressive versus nonaggressive lesions. Our study suggests that the lncRNA H19 could be a potential marker for breast cancer diagnosis, prognosis and risk management.
Telomeres protect the ends of chromosomes against illegitimate recombination and repair. They can be targets for G-quadruplex ligands and platinum complexes due to their repeated G-rich sequences. ...Protection of telomeres is ensured by a complex of six proteins, including TRF2, which inhibits the DNA damage response pathway. We analyzed telomere modifications induced in cancer cells by the experimental hybrid platinum complex, Pt-MPQ, comprising both an ethylene diamine monofunctional platinum complex and a G-quadruplex recognition moiety (MPQ). Pt-MPQ promotes the displacement of two telomeric proteins (TRF2 and TRF1) from telomeres, as well as the formation of telomere damage and telomere sister losses, whereas the control compound MPQ does not. This suggests that the platinum moiety potentiates the targeting of the G-quadruplex ligand to telomeres, opening a new perspective for telomere biology and anticancer therapy. Interestingly, the chemotherapy drug cisplatin, which has no specific affinity for G-quadruplex structures, partially induces the TRF2 delocalization from telomeres but produces less telomeric DNA damage, suggesting that this TRF2 displacement could be independent of G-quadruplex recognition.
Since tumor growth requires reactivation of telomerase (hTERT), this enzyme is a challenging target for drug development. Therefore, it is of great interest to identify telomerase expression and ...activity regulators. Retinoids are well-known inducers of granulocytic maturation associated with hTERT repression in acute promyelocytic leukemia (APL) blasts. In a maturation-resistant APL cell line, we have previously identified a new pathway of retinoid-induced hTERT transcriptional repression independent of differentiation. Furthermore, we reported the isolation of a cell variant resistant to this repression. Those cell lines could serve as unique tools to identify new telomerase regulators.
Using a microarray approach we identified the long non-coding RNA, H19 as a potential candidate playing a role in telomerase regulation. Expression of H19, hTERT, and hTR were examined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Telomerase activity was quantified by quantitative telomeric repeats amplification protocol (qTRAP). In vitro and in vivo assays were performed to investigate H19 function on telomerase expression and activity.
We showed both in retinoid-treated cell lines and in APL patient cells an inverse relationship between the expression of H19 and the expression and activity of hTERT. Exploring the mechanistic link between H19 and hTERT regulation, we showed that H19 is able to impede telomerase function by disruption of the hTERT-hTR interaction.
This study identifies a new way of telomerase regulation through H19's involvement and thereby reveals a new function for this long non-coding RNA that can be targeted for therapeutic purpose.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A series of bimetallic (NHC)PtX22(diamine) complexes have been prepared as a new chemotype for potential anticancer agents. These complexes display an uncommon set of structural features as far as ...they combine two bifunctional, trans-configured platinum centers. They display cytotoxic activities in the micromolar range on many cancerous cell lines and do not cross-react with cisplatin in A2780/DDP cell lines. They bind slowly to double-stranded DNAs, giving monoadducts as the major products. Pathways for cellular toxicity have been investigated for both mono- and bimetallic trans-(NHC)PtX2(amine) complexes. It has been highlighted that, unlike cisplatin, these complexes do not induce cell cycle arrest. They trigger apoptosis in A2780 cells by a pathway involving translocation of apoptosis-inducing factor and caspase 12 to the nucleus. Moreover, bimetallic complexes may induce necrosis.
The high affinity receptor 1 (NTSR1) and its agonist, neurotensin (NTS), are correlated with tumor cell aggressiveness in most solid tumors. As chemoresistance and tumor aggressiveness are often ...related, we decided to study the role of the NTSR1 complex within platinum-based chemotherapy responses. In an ovarian model, we studied carboplatin because it is the main standard of care for ovarian cancer.
Experimental tumors and
studies were performed using SKOV3 and A2780 cells treated with carboplatin, with or without a very specific NTSR1 antagonist, SR48692. We measured the effects of these treatments on cell apoptosis and apoptosis-related proteins, platinum accumulation in the cell and nucleus, and the expression and localization of platinum transporters. NTS and NTSR1 labeling was measured in patients with ovarian cancer.
SR48692 enhanced the response to carboplatin in ovarian cancer cells and experimental tumors. When SR48692 is combined with carboplatin, we noted a major improvement of platinum-induced DNA damage and cell death, as well as a decrease in tumor growth. The relationship of these results to clinical studies was made by the detection of NTS and NTSR1 in 72% and 74% of ovarian cancer, respectively. Furthermore, in a large series of high-grade ovarian cancer, NTSR1 mRNA was shown to correlate with higher stages and platinum resistance.
This study strongly suggests that the addition of NTSR1 inhibitor in combination with platinum salt-based therapy will improve the response to the drug.
.
Telomerase (hTERT) reactivation and sustained expression is a key event in the process of cellular transformation. Therefore, the identification of the mechanisms regulating hTERT expression is of ...great interest for the development of new anticancer therapies. Although the epigenetic state of hTERT gene promoter is important, we still lack a clear understanding of the mechanisms by which epigenetic changes affect hTERT expression. Retinoids are well‐known inducers of granulocytic maturation in acute promyelocytic leukemia (APL). We have previously shown that retinoids repressed hTERT expression in the absence of maturation leading to growth arrest and cell death. Exploring the mechanisms of this repression, we showed that transcription factor binding was dependent on the epigenetic status of hTERT promoter. In the present study, we used APL cells lines and publicly available datasets from APL patients to further investigate the integrated epigenetic events that promote hTERT promoter transition from its silent to its active state, and inversely. We showed, in APL patients, that the methylation of the distal domain of hTERT core promoter was altered and correlated with the outcome of the disease. Further studies combining complementary approaches carried out on APL cell lines highlighted the significance of a domain outside the minimal promoter, localized around 5 kb upstream from the transcription start site, in activating hTERT. This domain is characterized by DNA hypomethylation and H3K4Me3 deposition. Our findings suggest a cooperative interplay between hTERT promoter methylation, chromatin accessibility, and histone modifications that force the revisiting of previously proposed concepts regarding hTERT epigenetic regulation. They represent, therefore, a major advance in predicting sensitivity to retinoid‐induced hTERT repression and, more generally, in the potential development of therapies targeting hTERT expression in cancers.
Telomerase (hTERT) reactivation is a key event in oncogenesis. Although the epigenetic‐based regulation of hTERT is important, we still lack a clear understanding of the mechanisms by which epigenetic changes affect hTERT gene promoter. Our findings suggest a cooperative interplay between hTERT promoter methylation, chromatin accessibility, and histone modifications that force the revisiting of previously proposed concepts regarding hTERT regulation.
Sensitivity of tumor cells to anticancer therapy depends on the ability of the drug to induce apoptosis. However, multiple signaling pathways control this induction and thus determine this ...sensitivity. We report here that staurosporine, a well known inducer of apoptosis in a wide range of cell lines, displays distinct ability to trigger apoptosis in two different L1210 sublines (termed L1210/S and L1210/0). Staurosporine treatment resulted in an early cell death (within 3 h) in L1210/S cells, while in L1210/0 cells, death occurred only after 12 h. In both instances, death occurred by apoptosis. A broad spectrum caspase inhibitor, Z-VAD-fmk, blocked early apoptosis in L1210/S cells but did not confer any protection on late apoptosis in L1210/0 cells. Protection by Z-VAD-fmk observed in L1210/S cells was not lasting and unmasked a secondary process of cell death that also exhibited characteristics of apoptosis. Thus, staurosporine induces apoptotic cell death through at least two redundant parallel pathways. These two pathways normally coexist in L1210/S cells. However, the early cell death mechanism depending on caspase activation disguises the late caspase-independent apoptotic process. Staurosporine-induced apoptosis in L1210/0 cells develops only by the caspase-independent mechanism due to a general defect in caspase activation.
Cutaneous T‐cell lymphomas (CTCLs) are telomerase‐positive tumors expressing hTERT, although neither gene rearrangement/amplification nor promoter hotspot mutations could explain the hTERT ...re‐expression. As the hTERT promoter is rich in CpG, we investigated the contribution of epigenetic mechanisms in its re‐expression. We analyzed hTERT promoter methylation status in CTCL cells compared with healthy cells. Gene‐specific methylation analyses revealed a common methylation pattern exclusively in tumor cells. This methylation pattern encompassed a hypermethylated distal region from −650 to −150 bp and a hypomethylated proximal region from −150 to +150 bp. Interestingly, the hypermethylated region matches with the recently named TERT hypermethylated oncogenic region (THOR). THOR has been associated with telomerase reactivation in many cancers, but it has so far not been reported in cutaneous lymphomas. Additionally, we assessed the effect of THOR on two histone deacetylase inhibitors (HDACi), romidepsin and vorinostat, both approved for CTCL treatment and a DNA methyltransferase inhibitor (DNMTi) 5‐azacytidine, unapproved for CTCL. Contrary to our expectations, the findings reported herein revealed that THOR methylation is relatively stable under these epigenetic drugs' pressure, whereas these drugs reduced the hTERT gene expression.
Cutaneous T‐cell lymphomas (CTCLs) represent a group of lymphoproliferative disorders arising from the skin. CTCLs are characterized by hTERT gene expression despite the lack of hTERT amplifications or rearrangements. Here, we investigated hTERT promoter methylation and associated TERT hypermethylated oncogenic region (THOR) with hTERT reactivation in CTCL. Additionally, we evaluated THOR methylation and hTERT expression after treatment with epigenetic drugs. Altogether, our study offers a better understanding of the response to epigenetic drugs in patients with CTCL.
PDF
