Cisplatin-resistant Ovarian Carcinoma Cell Line Research Articles

Porphyrin metalla-assemblies coupled to cellulose nanocrystals for PDT and imaging applications

Photodynamic therapy (PDT) is an interesting and promising approach to tackle a broad spectrum of cancer. With the combination of a photosensitizer, light and oxygen, PDT achieves a unique selectivity by the production of localized reactive oxygen species (ROS) inside cells, which leads to their destruction. In addition, the luminescence properties of photosensitizers can be exploited to develop imaging tools. Unfortunately, the cancer selectivity and homogeneity of most photosensitizers are frequently limiting the performances of PDT and cancer detection/characterization by luminescence imaging. Consequently, our study aims to use cellulose nanocrystals to transport and deliver radiolabeled photo-responsive metalla-assemblies to create a new generation of theranostic agents for PDT and imaging applications. The synthesis, structural characterization, cytotoxicity evaluation, and in vivo biodistribution imaging of the compounds are presented. The best candidates show excellent biological activity and selectivity towards ovarian carcinoma cell line (A2780), cisplatin-resistant ovarian carcinoma cell line (A2780cis) versus normal human embryonic kidney cells (HEK293T), as well as efficient imaging properties, suggesting a potential use as multimodal theranostic agents.

Targeted biologic inhibition of both tumor cell-intrinsic and intercellular CLPTM1L/CRR9-mediated chemotherapeutic drug resistance

Recurrence of therapy-resistant tumors is a principal problem in solid tumor oncology, particularly in ovarian cancer. Despite common complete responses to first line, platinum-based therapies, most women with ovarian cancer recur, and eventually, nearly all with recurrent disease develop platinum resistance. Likewise, both intrinsic and acquired resistance contribute to the dismal prognosis of pancreatic cancer. Our previous work and that of others has established CLPTM1L (cleft lip and palate transmembrane protein 1-like)/CRR9 (cisplatin resistance related protein 9) as a cytoprotective oncofetal protein that is present on the tumor cell surface. We show that CLPTM1L is broadly overexpressed and accumulated on the plasma membrane of ovarian tumor cells, while weakly or not expressed in normal tissues. High expression of CLPTM1L is associated with poor outcome in ovarian serous adenocarcinoma. Robust re-sensitization of resistant ovarian cancer cells to platinum-based therapy was achieved using human monoclonal biologics inhibiting CLPTM1L in both orthotopic isografts and patient-derived cisplatin resistant xenograft models. Furthermore, we demonstrate that in addition to cell-autonomous cytoprotection by CLPTM1L, extracellular CLPTM1L confers resistance to chemotherapeutic killing in an ectodomain-dependent fashion, and that this intercellular resistance mechanism is inhibited by anti-CLPTM1L biologics. Specifically, exosomal CLPTM1L from cisplatin-resistant ovarian carcinoma cell lines conferred resistance to cisplatin in drug-sensitive parental cell lines. CLPTM1L is present in extracellular vesicle fractions of tumor culture supernatants and in patients’ serum with increasing abundance upon chemotherapy treatment. These findings have encouraging implications for the use of anti-CLPTM1L targeted biologics in the treatment of therapy-resistant tumors.

Enhanced anti-cancer activities of a gold(III) pyrrolidinedithiocarbamato complex incorporated in a biodegradable metal-organic framework

An anti-cancer active gold(III) pyrrolidinedithiocarbamato complex [(PDTC)AuIIICl2] (1) has been synthesized and characterized by means of X-ray crystallography. Compared to the pyrrolidinedithiocarbamate ligand itself, this gold(III) complex displays an up to 33-fold higher anti-cancer potency towards a panel of cancer cell lines including the cisplatin-resistant ovarian carcinoma cell line (A2780cis). As demonstrated by a set of Transwell® assay-based cytotoxicity experiments, incorporating this gold(III) complex in a zinc-based biodegradable metal-organic framework (MOF) displays a significant enhancement in anti-cancer activity towards A2780cis than the gold(III) complex alone.

HOTAIR is a potential target for the treatment of cisplatin‑resistant ovarian cancer.

Previous studies have demonstrated that the presence of Hox transcript antisense intergenic RNA (HOTAIR) is correlated with poor survival in several types of cancer, including breast cancer, and promotes tumor metastasis. Currently, little is known regarding the correlation between HOTAIR and chemoresistance in cancer. The current study aimed to investigate the role of HOTAIR in epithelial ovarian cancer, and the correlation between HOTAIR and cisplatin resistance. Reverse transcription-quantitative polymerase chain reaction was conducted to detect HOTAIR expression in the ovarian specimens and ovarian carcinoma cell lines. The results indicated that the expression level of HOTAIR was higher in epithelial ovarian cancer tissues than the level in the benign ovarian tissues. The expression level was also higher in late-stage malignant ovarian tumors compared with the level in early-stage tumors. Levels of HOTAIR were also higher in the SKOV-3CDDP/R cisplatin-resistant ovarian carcinoma cell line than in the SKOV-3 cisplatin-sensitive cell line. The knockdown of HOTAIR using siRNAs with transfection reagent suppressed cell proliferation, reduced the invasion ability of the cells and notably, it restored cisplatin-sensitivity of the cisplatin-resistant cells specifically by enhancing cisplatin-induced cytotoxicity and apoptosis in SKOV-3CDDP/R cells. In conclusion, HOTAIR may be used in the development of novel treatments for ovarian cancer, particularly those that are resistant to conventional therapies.

Cross-reacting material 197, a heparin-binding EGF-like growth factor inhibitor, reverses the chemoresistance in human cisplatin-resistant ovarian cancer.

Cross-reacting material 197 (CRM197), a specific HB-EGF inhibitor, has been proven to be a promising antitumor agent for ovarian cancer therapy. Our previous studies have shown that CRM197 has potent antitumor activity in human cisplatin-resistant ovarian cancer. However, the relationship between CRM197 and the resistance to cisplatin remains unclear. Here, we report that CRM197 significantly reverses the resistance to cisplatin in cisplatin-resistant ovarian carcinoma cell line (A2780/CDDP). We established xenograft nude mice models with A2780 and A2780/CDDP cells. Notably, we observed that CRM197 suppresses the expression of HB-EGF and epidermal growth factor receptor in A2780/CDDP cells and xenografts harboring the overexpression of HB-EGF and epidermal growth factor receptor. Experiments conducted in vitro and in vivo suggest that CRM197 markedly downregulates the expression of excision repair cross-complementing group 1 (P = 0.002) and DNA repair capacity in A2780/CDDP tumor (P < 0.001) by inactivation of extracellular signal-regulated kinase signaling, providing novel possible mechanisms for the ability of CRM197 to restore drug sensitivity. These results suggest that CRM197 as an HB-EGF inhibitor might be a cisplatin-chemosensitizing agent for the treatment of ovarian carcinoma with resistance to cisplatin.

The Cancer-associated K351N Mutation Affects the Ubiquitination and the Translocation to Mitochondria of p53 Protein

Stress-induced monoubiquitination of p53 is a crucial event for the nuclear-cytoplasm-mitochondria trafficking and transcription-independent pro-apoptotic functions of p53. Although an intact ubiquitination pathway and a functional nuclear export sequence are required for p53 nuclear export, the role of specific residues within this region in regulating both processes remains largely unknown. Here we characterize the mechanisms accounting for the nuclear accumulation of a new point mutation (Lys-351 to Asn) in the nuclear export sequence of p53 identified in a cisplatin-resistant ovarian carcinoma cell line (A2780 CIS). We found that K351N substitution abrogates the monoubiquitination of p53 induced by both Mdm2 and MSL2 E3-ligases. As a consequence, cells expressing p53 K351N mutant showed defects in cisplatin-induced translocation of p53 to mitochondria, Bax oligomerization, and mitochondrial membrane depolarization. These data identify K351N as a critical mutation of p53 that contributes to the development and maintenance of resistance to cisplatin.

Characterization of a new cancer-associated mutant of p53 with a missense mutation (K351N) in the tetramerization domain

Inactivation of the tumour suppressor p53 is central to carcinogenesis and acquisition of resistance to drug-induced apoptosis. The majority of alterations are missense mutations and occur within the DNA-binding domain. However, little is known about the point mutations in the tetramerization domain (TD). Here we investigated the properties of a new p53 mutant (Lys 351 to Asn) in the TD identified in a cisplatin-resistant ovarian carcinoma cell line (A2780 CIS). We found that K351N substitution significantly reduces the thermodynamic stability of p53 tetramers without affecting the overall half-life of the protein. Moreover, p53 K351N has a reduced ability to bind DNA and to trans-activate its specific target gene promoters, such as bax. Data obtained from the analysis of p53 subcellular localization revealed that K351N mutation inhibits the nuclear export of p53 and accumulation in the cytoplasm induced by cisplatin treatment. These results identify p53 K351N as a new cancer associated mutant with reduced tumour suppressor activity and altered functions in response to apoptotic stimuli.

The synthesis, chemical and biological properties of dichlorido(azpy)gold(III) chloride (azpy = 2-(phenylazo)pyridine) and the gold-induced conversion of the azpy ligand to the chloride of the novel tricyclic pyrido[2,1-c][1,2,4]benzotriazin-11-ium cation

A new Au(III) coordination compound with the ligand 2-(phenylazo)pyridine has been synthesized and fully characterized by means of elemental analysis, IR, UV–visible, conductivity measurements, NMR, electrospray ionization (ESI-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The chemical stability of the cation in this compound, [Au(azpy)Cl2]+ (abbreviated: Au-azpy), was analyzed by means of several physicochemical methods. While stable in the solid state, stability studies performed with the gold compound in solution showed an unexpected and unprecedented reactivity. A cationic organic derivative of 2-(phenylazo)pyridine, (abbreviated: pyrium), was produced from the solution and has been isolated as its chloride salt and characterized by crystal structure determination, elemental analysis, NMR, ESI-MS and conductivity studies in solution. This cyclization reaction is reported for the first time in the case of gold coordination compounds.The Au adduct and the pyrium cation were investigated as potential cytotoxic and anticancer agents, and both show moderate to high cytotoxic properties in cisplatin-sensitive and cisplatin-resistant ovarian carcinoma cell lines, A2780; and cisplatin-sensitive and cisplatin-resistant murine lymphocytic leukemia cell lines, L1210. Significant anticancer activity against the cisplatin resistant cell lines was found for the pyrium salt, ruling out the occurrence of cross resistance phenomena.

(S)‐HDAC‐42, A New HDAC Inhibitor in Ovarian Cancer Therapy

Although the current choice for ovarian cancer treatment is still cisplatin, the resistance to cisplatin therapy remains a critical obstacle in the management of refractory ovarian cancer. In the search for new therapies, histone deacetylases (HDACs) have been considered one of the most promising targets. HDAC inhibitors, such as trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA), have been reported to be effective against ovarian cancer cells in vitro and in vivo.. We have developed a new class of HDAC inhibitors by linking short-chain fatty acids with Zn2+-chelating motifs. Further structure-based optimization of these novel hydroxamate-tethered phenylbutyrate derivatives (HTPB) culminated in the generation of (S)-HDAC42, which, in this study, we show is a potent anti-cancer agent for ovarian cancer in vitro and in vivo. The treatment of both cisplatin-sensitive and -resistant ovarian cancer cell lines with (S)-HDAC42 restored histone acetylation and suppressed cell growth with IC50 values of about 1μM as determined by the MTT survival assay after 2 days treatment. Additionally, (S)-HDAC42 caused the accumulation of p21 and p27, down-regulation of Cdc2 and cyclin B1, and induced cell cycle arrest at G2/M phase. In the mean time, (S)-HDAC42 also induced cell differentiation and apoptosis. Furthermore, (S)-HDAC42 treatment of xenograft-bearing nude mice significantly inhibited tumor growth of the cisplatin-resistant ovarian carcinoma cell line CP70 compared to vehicle treatment. Moreover, the combination of (S)-HDAC42 and cisplatin treatments induced an enhanced suppression of tumor growth. In conclusion, these findings indicate that the novel HDAC inhibitor, (S)-HDAC42, is a promising agent for the treatment of ovarian cancer.

Altered ErbB Receptor Signaling and Gene Expression in Cisplatin-Resistant Ovarian Cancer

The majority of ovarian cancer patients are treated with platinum-based chemotherapy, but the emergence of resistance to such chemotherapy severely limits its overall effectiveness. We have shown that development of resistance to this treatment can modify cell signaling responses in a model system wherein cisplatin treatment has altered cell responsiveness to ligands of the erbB receptor family. A cisplatin-resistant ovarian carcinoma cell line PE01CDDP was derived from the parent PE01 line by exposure to increasing concentrations of cisplatin, eventually obtaining a 20-fold level of resistance. Whereas PE01 cells were growth stimulated by the erbB receptor-activating ligands, such as transforming growth factor-alpha (TGFalpha), NRG1alpha, and NRG1beta, the PE01CDDP line was growth inhibited by TGFalpha and NRG1beta but unaffected by NRG1alpha. TGFalpha increased apoptosis in PE01CDDP cells but decreased apoptosis in PE01 cells. Differences in extracellular signal-regulated kinase and phosphatidylinositol 3-kinase signaling were also found, which may be implicated in the altered cell response to ligands. Microarray analysis revealed 51 genes whose mRNA increased by at least 2-fold in PE01CDDP cells relative to PE01 (including FRA1, ETV4, MCM2, AXL, MT3, TRAP1, and FANCG), whereas 36 genes (including IGFBP3, TRAM1, and KRT4 and KRT19) decreased by a similar amount. Differential display reverse transcriptase-PCR identified altered mRNA expression for TCP1, SLP1, proliferating cell nuclear antigen, and ZXDA. Small interfering RNA inhibition of FRA1, TCP1, and MCM2 expression was associated with reduced growth and FRA1 inhibition with enhanced cisplatin sensitivity. Altered expression of these genes by cytotoxic exposure may provide survival advantages to cells including deregulation of signaling pathways, which may be critical in the development of drug resistance.

120 Synthesis and cytoxicity studies of platinum nucleobase adducts

A new Au(III) coordination compound with the ligand 2-(phenylazo)pyridine has been synthesized and fully characterized by means of elemental analysis, IR, UV–visible, conductivity measurements, NMR, electrospray ionization (ESI-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The chemical stability of the cation in this compound, [Au(azpy)Cl2]+ (abbreviated: Au-azpy), was analyzed by means of several physicochemical methods. While stable in the solid state, stability studies performed with the gold compound in solution showed an unexpected and unprecedented reactivity. A cationic organic derivative of 2-(phenylazo)pyridine, (abbreviated: pyrium), was produced from the solution and has been isolated as its chloride salt and characterized by crystal structure determination, elemental analysis, NMR, ESI-MS and conductivity studies in solution. This cyclization reaction is reported for the first time in the case of gold coordination compounds.The Au adduct and the pyrium cation were investigated as potential cytotoxic and anticancer agents, and both show moderate to high cytotoxic properties in cisplatin-sensitive and cisplatin-resistant ovarian carcinoma cell lines, A2780; and cisplatin-sensitive and cisplatin-resistant murine lymphocytic leukemia cell lines, L1210. Significant anticancer activity against the cisplatin resistant cell lines was found for the pyrium salt, ruling out the occurrence of cross resistance phenomena.

Assessment of gene expression profile by cDNA microarray analysis.

With the advent of cDNA microarray technology, variations in cellular transcriptional events can now be monitored simultaneously, and expression profile at each functional state can be established and compared to one another. Here we illustrate gene expression profile analysis of a cisplatin-resistant ovarian carcinoma cell line (A2780CP)and its parental A2780 cell line, and compare them to assess changes in gene expression related to resistance to cisplatin. Equal quantities(1 μg)of RNA from the cell lines are reverse-transcribed, labeled with P radioisotpe, and hybridized to ovary specific GeneFilters carrying more than 5,000 genes(GF223; Research Genetics, Huntsville, AL). Filter images are recorded by a phosphor-imager and analyzed comparatively using Pathways 3.0 software(Research Genetics). The upregulated and downregulated genes in cisplatin-resistant cells are identified and changes in selected genes are validated by a semiquantitative RT-PCR. This approach allows us to identify groups of genes, rather than just single genes, involved in a process, and can indicate which molecular and cellular events might be critical in such complex biological processes.

Cisplatin-induced response of c-jun N-terminal kinase 1 and extracellular signal-regulated protein kinases 1 and 2 in a series of cisplatin-resistant ovarian carcinoma cell lines

The cellular response to cisplatin involves activation of multiple signal transduction pathways, including the mitogen-activated protein (MAP) kinase pathways. In this study, we compared the cisplatin-induced activation of two MAP kinases, c-jun N-terminal kinase 1 (JNK1) and extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), in the cisplatin-sensitive ovarian carcinoma cell line A2780 and its derivative cisplatin-resistant cell lines CP70 and C200. Dose-dependent and time-dependent activation of JNK1 and ERK1/2 occurred in each of the three cell lines in response to cisplatin treatment. The requirement of higher concentrations of cisplatin for induction of maximum activation of JNK1 and ERK1/2 was correlated with increased levels of cisplatin resistance. In addition, inhibition of cisplatin-induced ERK activation, using the MAP/ERK kinase 1 synthetic inhibitor PD98059, resulted in enhanced sensitivity to cisplatin in all three cell lines. These results suggest that cisplatin-induced ERK1/2 activity is not responsible for the acquired cisplatin resistance in CP70 and C200 cells but rather provides a general cytoprotective effect in both cisplatin-sensitive and cisplatin-resistant cell lines. In conclusion, different patterns of cisplatin-induced JNK1 and ERK1/2 activation are observed in cell lines with different levels of cisplatin sensitivity, and inhibition of cisplatin-induced ERK1/2 activation enhances sensitivity to cisplatin in both cisplatin-sensitive and cisplatin-resistant cell lines.

Radiotherapy as a cisplatin-sensitizer in a resistant ovarian carcinoma cell line

Stage III ovarian carcinoma has shown resistance to adjuvant chemotherapy following surgical cytoreduction. With recurrence of ovarian carcinoma, cell lines may develop resistance to previously used chemotherapy. This contributes to the fact that survival rates for patients with ovarian carcinoma have not been dramatically improved in decades. The objective of this study is to evaluate radiotherapy as a cisplatin-sensitizer in a cisplatin-resistant ovarian carcinoma cell line. In vitro OVCAR-3 human ovarian carcinoma cells were irradiated with external beam radiation (XRT) at doses of 500, 1,500, and 4,500 centigray (cGy) in a single fractionation. Twelve hours after XRT, cells were treated with a dose of cisplatin for 2 hours (0, 1, 3, 9, and 90 micrograms/mL). Cell attachment was determined by cell counts using a hemocytometer under phase-contrast microscopy. Analysis of variance followed by the Student Newman Keuls Test were used for statistical analysis. Dose-response curves demonstrate the results of this study as follows: (1) XRT has a significant direct effect on cell attachment of OVCAR-3 cells in a dose-response relationship. (2) cisplatin has no effect on cell attachment in the absence of XRT. (3) When cells are exposed to XRT, cisplatin demonstrates a dose-response effect on cell attachment with a dose of XRT as low as 500 Gy. This in vitro study suggests that XRT sensitizes cisplatin-resistant OVCAR-3 to cisplatin. This occurred with doses of radiation low enough to suggest a potential clinical role in treating resistant ovarian carcinoma.