Thymidylate Synthase mRNA Research Articles

242 (PB230): Targeting Thymidylate Synthase mRNA regulatory element with a novel family of Berberine derivatives

242 (PB230): Targeting Thymidylate Synthase mRNA regulatory element with a novel family of Berberine derivatives

Rabdosianone I, a Bitter Diterpene from an Oriental Herb, Suppresses Thymidylate Synthase Expression by Directly Binding to ANT2 and PHB2.

Simple SummaryIn the present study, we found the novel pleiotropic regulation of the oncogene product thymidylate synthase (TS) by a chemical biology approach to identify rabdosianone I-binding proteins. Rabdosianone I, which is extracted from a traditional Asian herb Isodon japonicus Hara for longevity, suppressed TS expression at mRNA and protein levels. We immobilized rabdosianone I onto nano-magnetic beads and identified two mitochondrial proteins, adenine nucleotide translocase 2 (ANT2) and prohibitin 2 (PHB2), as the direct targets of rabdosianone I in cancer cells. Mechanistically, the knockdown of ANT2 or PHB2 promoted proteasomal degradation of the TS protein. In addition, PHB2 reduced TS mRNA levels. Thus, we provide previously unknown mechanisms of TS regulation by ANT2 and PHB2 and propose the possibility of rabdosianone I as a promising lead compound for the discovery of a novel TS suppressor.Natural products have numerous bioactivities and are expected to be a resource for potent drugs. However, their direct targets in cells often remain unclear. We found that rabdosianone I, which is a bitter diterpene from an oriental herb for longevity, Isodon japonicus Hara, markedly inhibited the growth of human colorectal cancer cells by downregulating the expression of thymidylate synthase (TS). Next, using rabdosianone I-immobilized nano-magnetic beads, we identified two mitochondrial inner membrane proteins, adenine nucleotide translocase 2 (ANT2) and prohibitin 2 (PHB2), as direct targets of rabdosianone I. Consistent with the action of rabdosianone I, the depletion of ANT2 or PHB2 reduced TS expression in a different manner. The knockdown of ANT2 or PHB2 promoted proteasomal degradation of TS protein, whereas that of not ANT2 but PHB2 reduced TS mRNA levels. Thus, our study reveals the ANT2- and PHB2-mediated pleiotropic regulation of TS expression and demonstrates the possibility of rabdosianone I as a lead compound of TS suppressor.

Plasma thymidylate synthase and dihydrofolate reductase mRNA levels as potential predictive biomarkers of pemetrexed sensitivity in patients with advanced non-small cell lung cancer.

BackgroundHigh levels of thymidylate synthase (TS) and dihydrofolate reductase (DHFR) expression in tumour tissues are an indicator of ineffective responses to pemetrexed-based chemotherapy in various tumours, including non-small cell lung cancer (NSCLC). However, tumour tissues are highly heterogeneous, so a single biopsy may not reflect genetic alterations during disease progression. This study investigated the potential use of plasma TS and DHFR mRNA levels as biomarkers for predicting sensitivity to pemetrexed-based chemotherapy.MethodsPlasma samples were obtained from 245 patients with advanced NSCLC and 30 healthy donors. Total RNA was extracted from the plasma samples, and TS and DHFR mRNA levels were determined via real-time PCR. TS and DHFR mRNA levels between cancer patients and healthy controls were compared. The association between plasma TS and DHFR mRNA levels and tumour response to pemetrexed/cisplatin chemotherapy was analysed.ResultsThe plasma TS and DHFR mRNA levels decreased in patients with advanced NSCLC compared with healthy controls. Moreover, plasma TS and DHFR mRNA levels negatively correlated with tumour response to pemetrexed/cisplatin chemotherapy in patients with advanced NSCLC. Overall survival time was prolonged in patients with low TS mRNA expression compared with those with high TS mRNA expression, although the difference was not statistically significant.ConclusionsLow expression levels of plasma TS and DHFR mRNA confer increased tumour sensitivity to pemetrexed/cisplatin chemotherapy in patients with advanced NSCLC. The results suggested that plasma TS and DHFR mRNA levels are promising biomarkers for choosing patients who are likely to respond and benefit the most from pemetrexed-based chemotherapy.

Expression of ERCC1 and TYMS in colorectal cancer patients and the predictive value of chemotherapy efficacy.

The present study investigated the expression of excision repair cross-complementing gene 1 (ERCC1) and thymidylate synthase (TYMS) in patients with colorectal cancer and the predictive value of chemotherapy. Eighty patients with colorectal cancer chemotherapy admitted to Binzhou Medical University Hospital from June 2013 to June 2015 were randomly selected, and 80 cancer tissues and 68 adjacent tissues were taken for analysis. RT-qPCR was used to detect ERCC1 as well as the expression level of TYMS. The relationship of the expression level with the chemotherapy efficacy, clinical pathology and survival time in colorectal cancer patients receiving standard chemotherapy, was compared. The expression of ERCC1 and TYMS mRNA in cancer tissues was significantly higher than that in the adjacent tissues (P<0.05). There was no correlation between ERCC1 mRNA expression, TYMS mRNA and clinicopathological features of colorectal cancer (P>0.05). The predictive effect of ERCC1 on colorectal cancer chemotherapy was 0.919 (95% CI, 0.862–0.976), P<0.001. The AUC of TYMS for predicting the efficacy of chemotherapy on colon cancer was 0.831 (95% CI, 0.735–0.926), and both had higher predictive values. The expression levels of ERCC1 and TYMS mRNA in 80 patients with colorectal cancer were divided into the low and high expression groups. The 3-year survival rate of patients in the low expression group was significantly higher than that in the high expression group, and the difference between the two groups was statistically significant (P<0.05). ERCC1 and TYMS had a high predictive value for the efficacy of chemotherapy in patients with colorectal cancer, and patients with lower expression of ERCC1 and TYMS had improved 3-year survival rates than patients with higher expression. Therefore, for patients with colorectal cancer, ERCC1 and TYMS can be used as predictors of the efficacy of chemotherapy.

Abstract 5189: Evaluation of thymidylate synthase mRNA expression in circulating tumor cells from non-metastatic colon and rectal patients

Abstract Background: colorectal cancer is the third leading cause of cancer death in the United States. With different behaviors, rectal cancer represents worse prognosis, even in the locally advanced setting, with therapy following three steps, consisting of neoadjuvant chemoradiation, surgery and adjuvant chemotherapy. For non-metastatic colon cancer, the main treatment is surgery and then, patients can or not undergo adjuvant chemotherapy. Studies have shown that circulating tumor cells (CTCs) may be involved in metastatization process. Thymidylate synthase (TYMS) acts in the 5-Fluorouracil metabolism, and when overexpressed, can confer resistance to treatment, which is commonly used for neoadjuvant treatment (rectal cancer) and in combination with oxaliplatin for adjuvant treatment (colon cancer). Excision repair cross complementation Group 1 (ERCC1) is a protein involved in damage DNA repair process that is described to confer resistance to platinum-based chemotherapy. Objective: evaluate the TYMS messenger RNA (mRNA) expression in CTCs isolated from patients with locally advanced colon and rectal cancers; and its predictable value in treatment resistance. For patients with colon cancer, we also evaluated the ERCC1 protein expression in order to verify the adjuvant therapy resistance related to oxaliplatin. Methods: We collected 10 mL of blood before the beginning of treatment and processed it on ISET® (Rarecells) device. RNAscope® Technology is a novel chromogenic in situ hybridization (CISH) assay for detection of target RNA within intact cells. The expression of TYMS target gene was performed using the kit from ACDbio, as described on the protocol, but standardized to cytology. Results: there were included 12 patients of each type of tumor. We analyzed samples from 12 rectal cancer patients, and found 10 with overexpression of TYMS mRNA in CTCs. Curiously, of the two patients who had TYMSneg mRNA expression; one had complete pathological response and the other substantial down-staging. In the positive cases, 50% presented response (partial or complete) and 50% present no response and systemic progression. This result will better understood when we perform the evaluation of the protein TYMS. Among the samples from colon cancer patients, we found 8 out 12 as CTCs TYMSpos mRNA expression. Unfortunately, our recent data does not allow us to do analysis of recurrence. However, one of the positive cases had recurrence. Among the 4 TYMSneg, one had recurrence. This can be explained by the positive immunocytochemical expression of the ERCC1 protein, which confers resistance to oxaliplatin. Our next steps are to expand the CISH experiments in a larger group of patients as well as to evaluate the TYMS protein expression in the same cases. Conclusion: our preliminary results point molecular analysis of CTCs as predictor marker of colon/rectal cancer treatments. Citation Format: Bianca Troncarelli Flores, Emne Ali Abdallah, Virgílio Souza e Silva, Celso Abdon Mello, Samuel Aguiar, Renata Mayumi Takahashi, Vanessa Silva Alves, Bruna Elisa Kupper, Ludmilla T. Chinen. Evaluation of thymidylate synthase mRNA expression in circulating tumor cells from non-metastatic colon and rectal patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5189.

Anticancer activity of the intraperitoneal-delivered DFP-10825, the cationic liposome-conjugated RNAi molecule targeting thymidylate synthase, on peritoneal disseminated ovarian cancer xenograft model.

IntroductionPeritoneal disseminated ovarian cancer is one of the most difficult cancers to treat with conventional anti-cancer drugs and the treatment options are very limited, although an intraperitoneal (ip) paclitaxel has shown some clinical benefit. Therefore, treatment of peritoneal disseminated ovarian cancer is a highly unmet medical need and it is urgent to develop a new ip delivered drug regulating the fast DNA synthesis.MethodsWe developed a unique RNAi molecule consisting of shRNA against the thymidylate synthase (TS) and a cationic liposome (DFP-10825) and tested its antitumor activity and PK profile in peritoneally disseminated human ovarian cancer ascites models by the luciferase gene-transfected SCID mice. DFP-10825 alone, paclitaxel alone or combination with DFP-10825 and paclitaxel were administered in an ip route to the tumor-bearing mice. The TS expression level was measured by conventional RT-PCR. The anti-tumor activity and host survival benefit by DFP-10825 treatment on tumor-bearing mice were observed as resulting from the specific TS mRNA knock-down in tumors.ResultsDFP-10825 alone significantly suppressed the growth of SKOV3-luc tumore ascites cells and further extended the survival time of these tumor-bearing mice. Combination with the ip paclitaxel augmented the antitumor efficacy of DFP-10825 and significantly prolonged the survival time in the tumor-bearing mice. Short-hairpin RNA for TS (TS shRNA) levels derived from DFP-10825 in the ascetic fluid were maintained at a nM range across 24 hours but not detected in the plasma, suggesting that TS shRNA is relatively stable in the peritoneal cavity, to be able to exert its anti-tumor activity, but not in blood stream, indicating little or no systemic effect.ConclusionCollectively, the ip delivery of DFP-10825, TS shRNA conjugated with cationic liposome, shows a favorable antitumor activity without systemic adverse events via the stable localization of TS shRNA for a sufficient time and concentration in the peritoneal cavity of the peritoneally disseminated human ovarian cancer-bearing mice.

Predictive Significance of Thymidylate Synthase Expression in Non-small Cell Lung Cancer.

To date, many studies have suggested that thymidylate synthase (TS) could be used as a prognostic and predictive marker in non-small cell lung cancer (NSCLC) patients. However, results have been contradictory. The aim of this study was to evaluate TS mRNA levels in tumor tissue of NSCLC patients who underwent complete surgical resection and to analyze its prognostic and predictive potential. The study group consisted of 64 patients who underwent curative lung resection. Paired lung tissue samples were taken directly from the tumor tissue and from adjacent, histologically cancer-free lung tissue. The quantitative estimation of TS expression was performed by reverse transcription real-time polymerase chain reaction (RT-qPCR). The relationship between TS expression level and disease-free interval (DFI) and overall survival (OS) was analyzed. There was significantly higher TS expression in NSCLC tumor tissue comparing to normal lung tissue. In the group of patients who received adjuvant chemotherapy based on platinum derivatives in combination with paclitaxel or gemcitabine, we found shorter DFI (p=0.0473) and OS (p=0.0053) in those with high expression of TS. Our results demonstrated the relationship of high tumor tissue TS levels to adverse prognosis in patients undergoing adjuvant chemotherapy. TS is a non-specific tumor marker with respect to NSCLC, therefore we think that its best use would be as a member of the panel of predictors of adjuvant treatment efficacy.

P1.02-044 Relationship between RET Rearrangement and Thymidylate Synthase mRNA Expression in Non-Small Cell Lung Cancer Tissues

P1.02-044 Relationship between RET Rearrangement and Thymidylate Synthase mRNA Expression in Non-Small Cell Lung Cancer Tissues

Protein and mRNA expression of folic acid-associated enzymes as biomarkers for the cytotoxicity of the thymidylate synthase-targeted drugs, pemetrexed and S-1, in non-small cell lung cancer.

The thymidylate synthase (TS)-targeted drugs, pemetrexed and S-1, exert an important role in advanced non-small cell lung cancer (NSCLC) treatment; folic acid-associated enzymes are expected to behave as biomarkers, although their role has yet to be fully elucidated. In the present study, a single-institutional prospective analysis, in which the mRNA and protein expression levels of five folic acid-associated enzymes were evaluated with surgical specimens of NSCLC, was performed. Drug sensitivity was evaluated using a collagen gel droplet-embedded culture drug sensitivity test (CD-DST) in vitro. A total of 50 patients with NSCLC were enrolled, and the mRNA and protein expression levels of five enzymes were assessed in 47 and 46 patients, respectively. A significant association was identified between mRNA and protein expression in TS (r=0.6266), but the correlation between mRNA and protein expression levels for the other four enzymes was poor. TS mRNA expression was significantly higher in poorly differentiated tumors compared with moderately differentiated tumors (P=0.0399). TS protein expression was significantly higher in patients with pleural invasion or lymphatic invasion compared with those lacking them (P=0.027 and 0.030, respectively). CD-DST revealed that none of the tumors that were sensitive to pemetrexed, but not to S-1, were well differentiated, whereas none of the tumors that were sensitive to S-1, but not to pemetrexed, were poorly differentiated. More prominent vascular invasion was observed in the tumors that were sensitive to S-1. The only factors that exhibited the potential to discriminate the cytotoxicity of pemetrexed from S-1 were tumor differentiation grade and vascular invasion.

MALAT1 is a prognostic factor in glioblastoma multiforme and induces chemoresistance to temozolomide through suppressing miR-203 and promoting thymidylate synthase expression.

Glioblastoma multiforme (GBM) is the most malignant brain tumor with limited therapeutic options. Temozolomide (TMZ) is a novel cytotoxic agent used as first-line chemotherapy for GBM, however, some individual cells can't be isolated for surgical resection and show treatment-resistance, thus inducing poor prognosis. By using the HiSeq sequencing and bioinformatics methods, we identified lncRNAs showing different expression levels in TMZ-resistant and non-resistant patients. RT-qPCR was then performed in tissues and serum samples, and lncRNA MALAT1 was finally identified to show considerable discriminating potential to identify responding patients from non-responding patients. Moreover, high serum MALAT1 expression was associated with poor chemoresponse and survival in GBM patients receiving TMZ treatment. Subsequently, the TMZ resistant cell lines were established, and the CCK8 assay showed that lncRNA MALAT1 knockdown significantly reversed TMZ resistance in GBM cells. The gain and loss-function experiments revealed that miR-203 was down-regulated by MALAT1 and this interaction has reciprocal effects. Besides, thymidylate synthase (TS) mRNA was identified as a direct target of miR-203. LncRNA MALAT1 inhibition re-sensitized TMZ resistant cells through up-regulating miR-203 and down-regulating TS expression. On the other hand, MALAT1 overexpression promoted resistance by suppressing miR-203 and promoting TS expression. In conclusion, our integrated approach demonstrates that enhanced expression of lncRNA MALAT1 confers a potent poor therapeutic efficacy and inhibition of MALAT1 levels could be a future direction to develop a novel therapeutic strategy to overcome TMZ resistance in GBM patients.

The role of pharmacogenetics in the new ESMO colorectal cancer guidelines.

The role of pharmacogenetics in the new ESMO colorectal cancer guidelines.

Gambogic acid potentiates the chemosensitivity of colorectal cancer cells to 5-fluorouracil by inhibiting proliferation and inducing apoptosis.

Chemotherapy using 5-fluorouracil (5-FU) for colorectal cancer (CRC) has low specificity and response rates, leading to severe side effects. Gambogic acid (GA), a traditional Chinese medicine, has multi-targeted anticancer effects, including growth inhibition and apoptosis induction. However, it is unclear whether a combination of 5-FU and GA has synergistic anticancer effects in CRC cells. In this study, SW480 and HCT116 human CRC cells and human intestinal epithelial cells (IECs) were treated with different concentrations of 5-FU, GA or 5-FU+GA. A Cell Counting kit-8 assay was conducted to quantify cell proliferation. The combination index (CI) was calculated and the median-effect principle was applied to analyze the interaction between 5-FU and GA. Flow cytometry was used to determine the percentage of cells undergoing apoptosis. Reverse transcription-quantitative polymerase chain reaction and western blotting were applied to measure P53, survivin and thymidylate synthase (TS) mRNA and protein levels. It was found that 5-FU+GA more pronouncedly inhibited cell growth and induced apoptosis, compared with either monotherapy. CI values <1 indicated the synergistic effects of the drugs. 5-FU+GA further decreased P53, survivin and TS mRNA and protein levels in the two CRC cell lines compared with single drugs, whereas increased P53 protein levels were observed in HCT116 cells. Moreover, 5-FU+GA did not increase cytotoxicity to IECs. These results demonstrate that GA enhances the anticancer effects of 5-FU on CRC cells. Combined treatment with 5-FU and GA is effective and safe for CRC cells, and may become a promising chemotherapy treatment.

P2.03a-007 Pem/CBP/Bev Followed by Pem/Bev in Hispanic Patients with NSCLC: Outcomes According to Combined Score of TS, ERCC1 and VEGF Expression

To evaluate the efficacy and safety of pemetrexed, carboplatin and bevacizumab (PCB) followed by maintenance pemetrexed and bevacizumab (PB) in chemotherapy-naïve patients with stage IV non-squamous non-small cell lung cancer (NSCLC) through the influence of thymidylate synthase (TS), ERCC1 and VEGF mRNA expression on several outcomes. The primary endpoints were the overall response rate (ORR), progression-free survival (PFS) and overall survival (OS). Patients were administered pemetrexed (500 mg/m2), carboplatin (AUC, 5.0 mg/ml/min) and bevacizumab (7.5 mg/kg) intravenously every three weeks for up to four cycles. Maintenance pemetrexed and bevacizumab was administered until disease progression or unacceptable toxicity. One hundred forty-four Hispanic patients with a median follow-up of 13.8 months and a median number of maintenance cycles of 6 (range, 1- 32) were assessed. The ORR among the patients was 66% (95% CI, 47% to 79%). The median progression-free and overall survival (OS) rates were 7.9 months (95% CI, 5.9-10.0 months) and 21.4 months (95% CI, 18.3 to 24.4 months), respectively. Median TS, ERCC1 and VEGF mRNA levels were 1.45 (range, 0.17–2.52), 0.58 (range, 0.44-1.20), and 2.72 (range, 1.84-3.21), respectively. OS was significantly higher in patients with the lowest TS mRNA levels [29.6 months (95% CI 26.2-32.9) compared with those with higher levels 9.3 months (95% CI 6.6-12.0); p=0.0001]. ERCC1 mRNA levels also influenced the OS [median for ERCC1 mRNA˂0.58 28.7 months (95% CI 26.3-31.2) vs. ERCC1 mRNA˃0.58 11.1 months (95% CI 9.6-12.7); p=0.0001] as well as VEGF mRNA levels [median OS for VEGF mRNA˂2.72 26.4 months (95% CI 22.8-30.0) vs. VEGF mRNA˃2.72 18.2 months (95% CI 8.4-27.9); p=0.009]. TS mRNA did not influence treatment response, however the ORR was significantly higher in patients with low levels of ERCC1 (p = 0.003) and elevated VEGF (p = 0.005). Multivariate analysis found that TS mRNA levels (p=0.0001), VEGF mRNA levels (p=0.007) and PS (p=0.014) were independent prognostic factors. Overall, PCB followed by maintenance pemetrexed and bevacizumab was in Hispanic patients with non-squamous NSCLC. This regimen was associated with prolonged OS, particularly in patients with low TS, ERCC1 and VEGF mRNA expression. These biomarkers alone or in combination may be useful to assess the prognosis of patients with NSCLC treated with CBP/Pem/Bev.

P2.03a-027 A Phase I Study of the Non-Receptor Tyrsine Kinase Inhibitor (NKI) Bosutinib in Combination with Pemetrexed in Patients with Advanced Solid Tumors: Topic: Clinical Trials

The combination of cytotoxic chemotherapy with Src signaling pathway inhibitors represents a potential novel strategy to improve tumor response. Preclinical data suggests that thymidylate synthase (TS) and Src act via a common pathway and their overexpression has prognostic significance. Ceppi et al, explored the concept that Src inhibitors could be synergistic in combination with pemetrexed. Using immunohistochemical detection, Src kinase activation, evaluated by a phosphospecific antibody, was associated with higher TS expression in tumor specimens. Src-inhibition synergistically enhanced pemetrexed-cytotoxicity in human A549 lung cancer cells. Treatment with a Src inhibitor prevented up-regulation of TS mRNA and protein levels induced by pemetrexed that increased resistance to treatment. This suggests that Src represents a potential target to improve the efficacy of TS-inhibiting agents mainly in treatment of metastatic adenocarcinoma of the lung and malignant mesothelioma. Bosutinib is a NKI that inhibits the Abelson and Src kinases approved to treat CML. Hypothesis. Bosutinib can be safely administered in combination with pemetrexed with the MTD determined. Objectives. 1) Determine the dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) of bosutinib combined with pemetrexed, 2) Estimate the tumor response rate (RR), progression-free survival (PFS) and overall survival (OS) for patients with selected advanced cancers treated with this combination, 3) Explore potential biomarkers for treatment selection and response, including expression of Src kinase, phosphorylated Src kinase, and expression of potential modifying genes including K-ras, and 4) Determine the effect on the pharmacokinetics of each drug. This is a single institution phase I dose-escalation study for patients with selected advanced solid malignancies eligible to receive pemetrexed and ECOG performance status 0-2. Sequential dose cohorts of 3-6 patients will be treated. The starting dose of bosutinib is 200 mg daily in addition to pemetrexed 500 mg/m2 (Table 1).Tabled 1Dose level (cohort)number of patientsBosutinib dose (mg)Pemetexed dose (mg/m2)-23-6100400-13-610050013-620050023-630050033-640050043-6500500Expansion cohort10-12MTD500 Open table in a new tab not applicable. not applicable.

Efficacy of crizotinib and pemetrexed-based chemotherapy in Chinese NSCLC patients with ROS1 rearrangement.

BackgroundROS1 rearrangement is a novel molecular subgroup of non-small-cell lung cancer (NSCLC). This study aimed to investigate the efficacy of crizotinib and pemetrexed-based chemotherapy in Chinese NSCLC patients with ROS1 rearrangement.ResultsA total of 2309 patients received ROS1 fusion detection and 51(2.2%) patients had ROS1 rearrangement. There was no significant difference between ROS1 fusion-positive and fusion-negative cohorts in demographic data. For the ROS1 fusion-positive patients, crizotinb-treated group had a higher overall response rate (ORR, 80.0%), disease control rate (DCR, 90.0%) and longer progression-free survival (PFS, 294 days) compared with the rates in pemetrexed-treated group (ORR, 40.8%; DCR, 71.4%; PFS, 179 days) and non-pemetrexed-treated group (ORR, 25.0%; DCR, 47.7%; PFS, 110 days). Besides, ORR, DCR and PFS were similar in three major ROS1 fusion partners. For the first-line treatment, patients received pemetrexed had a significant longer PFS than those received non-pemetrexed chemotherapy (209 vs. 146 days, P = 0.0107). In pemetrexed-treated cohorts, ROS1-positive patients with low TS expression had a statistically significant longer PFS than those with high TS expression (184 vs. 110 days, P = 0.0105).Materials and methodsWe retrospectively identified patients with NSCLC who were screened for ROS1 fusion using multiplex reverse transcription-polymerase chain reaction (RT-PCR) from October 2013 to February 2016. The thymidylate synthase (TS) mRNA levels were tested using quantitative real-time RT-PCR.ConclusionsCrizotinib was also highly active at treating Chinese NSCLC patients with ROS1 rearrangement. TS expression could predict the efficacy of pemetrexed-based therapy in ROS1 fusion-positive patients.

Astaxanthin enhances pemetrexed-induced cytotoxicity by downregulation of thymidylate synthase expression in human lung cancer cells

Pemetrexed, a multitargeted antifolate agent, has demonstrated clinical activity in non-small cell lung cancer (NSCLC) cells. Increased expression of thymidylate synthase (TS) is thought to be associated with resistance to pemetrexed. Astaxanthin exhibits a wide range of beneficial effects including anti-cancer and anti-inflammatory properties. In this study, we showed that down-regulating of TS expression in two NSCLC cell lines, human lung adenocarcinoma H1650 and squamous cell carcinoma H1703 cells, with astaxanthin were associated with decreased MKK1/2-ERK1/2 activity. Enforced expression of constitutively active MKK1 (MKK1-CA) vector significantly rescued the decreased TS mRNA and protein levels in astaxanthin-treated NSCLC cells. Combined treatment with a MKK1/2 inhibitor (U0126 or PD98059) further decreased the TS expression in astaxanthin-exposed NSCLC cells. Knockdown of TS using small interfering RNA (siRNA) or inhibiting ERK1/2 activity enhanced the cytotoxicity and cell growth inhibition of astaxanthin. Combination of pemetrexed and astaxanthin resulted in synergistic enhancing cytotoxicity and cell growth inhibition in NSCLC cells, accompanied with reduced activation of phospho-MKK1/2, phopho-ERK1/2, and TS expression. Overexpression of MKK1/2-CA reversed the astaxanthin and pemetrexed-induced synergistic cytotoxicity. Our findings suggested that the down-regulation of MKK1/2-ERK1/2-mediated TS expression by astaxanthin is an important regulator of enhancing the pemetrexed-induced cytotoxicity in NSCLC cells.

Abstract 2159: In vitro characterization of PTAU and FU interactions in colon cancer cells

Abstract Background: Fluorouracil (FU) remains a main anticancer therapy for colorectal cancer (CRC) and other solid tumors. The mechanism of action of FU is associated with inhibition of thymidylate synthase (TS) and incorporation of its metabolites into RNA and DNA. High toxicity and wide-spread chemoresistance, however, have limited the utilization of FU-based therapies. Five intracellular enzymes, thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), methylenetetrahydrofolate reductase (MTHFR), thymidine phosphorylase (TP), and uridine phosphorylase (UP) are key determinants of FU sensitivity or resistance. Combination therapies aimed at improving the bioavailability of FU and reducing host toxicity has been evaluated. Recently, our group developed a new uridine phosphorylase inhibitor, 5-phenylthio-acyclouridine (PTAU) that has shown promise in reducing host toxicity and increasing FU efficacy in vivo. The current studies were to characterize interactions of PTAU and FU in vitro and to assess its effects on key metabolic enzymes in human colon cancer cells. Hypothesis: We hypothesized that inhibition of uridine phosphorylase by PTAU would ameliorate the toxic effects of FU and enhance its efficacy by permitting increased doses of FU. Methods: Three colon cancer cell lines with differing p53 status, HCT116-p53wt (wild-type), HCT116-p53null, and HT-29 (p53-mutant); and a normal colonic epithelial cell line, CRL-1790, were used. Doubling times were determined, and IC50 values for FU were derived from kill curves using MTT assay. Cells were treated for 72 hours with IC50 doses of FU, PTAU (100 μM) or uridine (25 μM), alone or in combination, or with the solvent, DMSO. mRNA levels for DPD, TS, TP, and UP were quantitated by qRT-PCR; for intracellular protein expression, cells were fixed and stained with monoclonal antibodies and analyzed by flow cytometry. Results: FU sensitivity correlated with cell doubling times. Basal expression of FU metabolic enzymes differed between CRC and normal cells. mRNAs for DPD and UP were higher in normal relative to cancer cells, but TS mRNA was higher in cancer cells. FU treatment upregulated mRNA expression of DPD, UP, and TS in cancer cells but not in normal cells. Only in cancer cells, DPD induction by FU was potentiated by PTAU. In contrast, treatment with FU decreased protein levels of DPD, TP, and TS in cancer cells. PTAU induced TS protein expression in cancer cells, an effect that was reduced by co-treatment with FU. Conclusions: FU induces mRNA levels of DPD, UP, and TS in cancer cell lines, but protein levels are reduced; the discrepancy between mRNA and protein levels following FU treatment underscores the need for evaluation of colon cancer samples to assess response to FU therapy. This work was supported by a Supplement of the MSM/TU/UABCCC U54 Partnership grant (3U54-CA118948-09S1) from NIH. Citation Format: Esther A. Suswam, Gaurav Kumar, Hyung-Gyoon Kim, Mohamed Osmar, Mahmoud H. el Kouni, Upender Manne. In vitro characterization of PTAU and FU interactions in colon cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2159.

Pemetrexed/Carboplatin/Bevacizumab followed by Maintenance Pemetrexed/Bevacizumab in Hispanic Patients with Non-Squamous Non-Small Cell Lung Cancer: Outcomes according to Thymidylate Synthase Expression.

ObjectiveTo evaluate the efficacy and safety of pemetrexed, carboplatin and bevacizumab (PCB) followed by maintenance therapy with pemetrexed and bevacizumab (PB) in chemotherapy-naïve patients with stage IV non-squamous non-small cell lung cancer (NSCLC) through the influence of thymidylate synthase (TS) protein and mRNA expression on several outcomes. The primary endpoints were the overall response rate (ORR), progression-free survival (PFS) and overall survival (OS).MethodsA cohort of 144 patients were administered pemetrexed (500 mg/m2), carboplatin (AUC, 5.0 mg/ml/min) and bevacizumab (7.5 mg/kg) intravenously every three weeks for up to four cycles. Maintenance PB was administered until disease progression or unacceptable toxicity.ResultsOne hundred forty-four Colombian patients with a median follow-up of 13.8 months and a median number of 6 maintenance cycles (range, 1–32) were assessed. The ORR among the patients was 66% (95% CI, 47% to 79%). The median PFS and (OS) rates were 7.9 months (95% CI, 5.9–10.0 months) and 21.4 months (95% CI, 18.3 to 24.4 months), respectively. We documented grade 3/4 hematologic toxicities, including anemia (14%), neutropenia (8%), and thrombocytopenia (16%). The identified grade 3/4 non-hematologic toxicities were proteinuria (2%), venous thrombosis (4%), fatigue (11%), infection (6%), nephrotoxicity (2%), and sensory neuropathy (4%). No grade >3 hemorrhagic events or hypertension cases were reported. OS was significantly higher in patients with the lowest TS mRNA levels [median, 29.6 months (95% CI, 26.2–32.9)] compared with those in patients with higher levels [median, 9.3 months (95% CI, 6.6–12.0); p = 0.0001]. TS expression (mRNA levels or protein expression) did not influence the treatment response.ConclusionOverall, PCB followed by maintenance pemetrexed and bevacizumab was effective and tolerable in Hispanic patients with non-squamous NSCLC. This regimen was associated with acceptable toxicity and prolonged OS, particularly in patients with low TS expression. We found a role for Ki67 and TS expression as prognostic factors.

Inhibition of NF-κB translocation by curcumin analogs induces G0/G1 arrest and downregulates thymidylate synthase in colorectal cancer

Cell cycle progression and DNA synthesis are essential steps in cancer cell growth and resistance. Thymidylate synthase (TS) is a therapeutic target for 5FU. Curcumin is a potent inhibitor of NF-κB. EF31 and UBS109 are potent synthetic analogues of curcumin. We tested the hypothesis that inhibition of NF-κB translocation by curcumin and its analogs EF31 and UBS109 can inhibit cell cycle progression and downregulate TS levels in colorectal cancer (CRC) cell lines. Two CRC cell lines (HCT116 and HT-29) were either untreated (control) or treated with IC50 concentrations of curcumin, EF31 UBS109 led to G0/G1 cell cycle arrest. Treatment with curcumin, EF31 or UBS109 inhibited NF-κB, downregulated survival pathways and inhibited cell cycle progression. Arrest in the G0/G1 phase was associated with downregulation of the transcription factor E2F-1 and its target gene TS. NF-κB over-expression induced E2F-1 and TS protein and mRNA levels in both cell lines. EF31 and UBS109 treatment significantly decreased tumor growth in compared to untreated tumors. EF31 and UBS109 are promising agents for the prevention and treatment of CRC.

Abstract 3778: Inhibition of NF-κB translocation induces G0/G1 arrest and downregulates thymidylate synthase in colorectal cancer

Abstract Purpose Objectives: Cell cycle progression and DNA synthesis are essential steps in cancer cell growth and resistance. Thymidylate synthase (TS) is a therapeutic target for 5FU. Curcumin is a potent inhibitor of NF-κB. We tested the hypothesis that NF-κB translocation inhibition by curcumin and its analogs can inhibit cell cycle progression and downregulate TS levels in colorectal cell lines. Methods: Two colorectal cancer cell lines were usedHCT-116 and HT-29. Cells were either untreated (control) or treated with curcumin (20μM), EF31 (7.5μM for HCT-116 and 2.5μM for HT-29) and UBS109 (620nM for HCT-116 and 1.25μM for HT-29) for 24 hours. Western blot and RT-PCR analyses were carried out to determine the effect of curcumin and its analogues EF31 and UBS109 on different signal molecules involved in cell cycle arrest and DNA synthesis. Electromobility shift assay (EMSA) was performed in colon cancer cells to evaluate the effects of curcumin and its analogues on NF-κB activity. A subcutaneous xenograft mouse model was used to evaluate the in vivo effects of curcumin analogues. Results: Treatment with curcumin and its analogues inhibited cyclin D1, pRb and E2F-1 at the transcriptional and translational level and induced p21, leading to G0/G1 cell cycle arrest. NF-κB over-expression induced E2F-1 and TS protein and mRNA levels in both cell lines. Arrest in the G0/G1 phase was associated with downregulation of the transcription factor E2F-1 and its target gene TS. Similar effects were observed in tumors from animals treated with EF31 and UBS109. Further, EF31 and UBS109 treatment significantly decreased the tumor growth compared to untreated tumors. Conclusion: In this study, we present in vitro and in vivo data to support the use of curcumin analogs in colorectal cancer based on their ability to reduce expression of proteins important for DNA repair and cell cycle progression leading to cell cycle arrest and tumor shrinkage. Accordingly, combining curcumin analogs with chemotherapy is a rational approach for future drug development in colorectal cancer. Citation Format: Ganji Purnachandra Nagaraju, Alese Olatunji, Sandhya Gupta, Mamoru Shoji, Bassel F. El-Rayes. Inhibition of NF-κB translocation induces G0/G1 arrest and downregulates thymidylate synthase in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3778. doi:10.1158/1538-7445.AM2015-3778