Thymidine phosphorylase mRNA expression may be a predictor of response to post-operative adjuvant chemotherapy with S-1 in patients with stage III colorectal cancer

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

Significance of expression of pyrimidine metabolizing genes in colon cancer

BACKGROUND AND STUDY AIMS

The reprogramming of metabolic pathways in tumour cells is a crucial step to meet the increased requirements for their own growth. This process occurs through alterations in gene expression, polymorphisms, and epigenetic dysregulation of a number of metabolic genes. Several metabolic enzymatic pathways such as pyrimidine-metabolizing enzymes have been implicated in tumorigenesis and tumor progression.

PATIENTS AND METHODS

We measured the relative expression levels of three pyrimidine-metabolizing genes-thymidylate synthase (TYMS), thymidine phosphorylase (TYMP), and dihydropyrimidine dehydrogenase (DPYD)-in tumor tissue and adjacent normal-appearing mucosa in 50 colon cancer (CC) patients using real-time reverse-transcription polymerase chain reaction. Gene expression was also studied in relation to demographic and pathological criteria.

RESULTS

The gene expression levels of both TYMS and TYMP were significantly higher in tumor tissue than normal adjacent tissue. Further, they showed an agreeable level of diagnostic performance as a means to discriminate between normal and tumor tissue; TYMS had high specificity (94%) but moderate sensitivity (60%), while TYPM showed average sensitivity (70%) and specificity (76%). Although DPYD expression was lower in tumor tissue than paracancerous tissue, this level did not reach the statistical significance. TYMS expression was significantly higher in moderately and poorly differentiated tumors than in well-differentiated ones. There was no significant association between gene expression and the remaining clinicopathological criteria (e.g., age, sex, tumor location, and metastasis). We found a positive correlation between the gene expression levels of TYMS and DPYD.

CONCLUSION

TYMS and TYMP messenger RNA levels seem to be plausible indicators in the diagnosis of CC, although further studies are warranted for validation.

Deregulation of folate pathway gene expression correlates with poor prognosis in acute leukemia

The present study analyzed the mRNA expression levels of genes involved in the transport and metabolism of methotrexate (MTX) (RFC1, ABCC1, ABCB1, GGH, FPGS, ATIC, TS, MTHFR, MTRR, MS and MTHFD1) in patients with acute leukemia (AL). The expression levels of the examined genes were analyzed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) in patients with AL (ALL:50/AML:19) and 66 healthy individuals. The mRNA expression levels of RFC1, MS, MTRR, MTHFR and ABCB1 were decreased (P<0.05), while those of GGH, FPGS, TS and MTHFD1 (P<0.05) were overexpressed in patients with AL. Patients with high mRNA levels of GGH (OR=4.28, 95% CI=1.29–14.14), TS (OR=7.14, 95% CI 1.84–27.81), MTHFR (OR=4.81, 95% CI=1.31–17.64), ABCB1 (OR=4.61, 95% CI=1.33–15.97) and ABCC1 (OR=5.50, 95% CI=1.12–27.06) had a higher chance of relapse. Interestingly, high mRNA levels of RFC1 are a protective factor in the risk of AL relapse (OR=0.22, 95% 0.06–0.80). The results of the present study indicated that deregulation of folate pathway gene expression is associated with poor prognosis in AL and that the expression levels of these markers could serve as novel molecular targets for the treatment of patients with AL.

PIK3R3 promotes chemotherapeutic sensitivity of colorectal cancer through PIK3R3/NF-kB/TP pathway

Phosphoinositide-3-kinase regulatory subunit 3(PIK3R3) is overexpressed in different types of human cancer. We previously reported the important role of PIK3R3 in colorectal cancer (CRC). However, the prognosis effect of PIK3R3 in CRC is still remaining unclear. In this study, we explored online clinical databases to analyze the prognosis differences between higher and lower expression of PIK3R3 in CRC patients. Interestingly, we found that better disease-free survival (DFS) were occurred in patients with higher expression of PIK3R3, but there is no significant difference in overall survival (OS). For further, we showed that PIK3R3 could enhance 5-FU induced apoptosis by regulating the expression of thymmidine phosphorylase (TP). In conclusion, PIK3R3 could be considered as a predictor of 5-FU sensitivity for personalized treatment, and a therapeutic target for colorectal cancer.

Thymidine phosphorylase expression and prognosis in colorectal cancer treated with 5-fluorouracil-based chemotherapy: A meta-analysis

In the past decades, various studies have suggested a possible link between thymidine phosphorylase (TP) level and colorectal cancer (CRC) treated with 5-fluorouracil (5-FU)-based chemotherapy; however, they have arrived at inconsistent results. Therefore, the present meta-analysis aimed to disclose a more comprehensive evaluation of this relationship. PubMed, the Cochrane Library, Ovid MEDLINE, Embase and China National Knowledge Infrastructure were systematically searched for studies that evaluated the prognostic value of TP in CRC. Stata 12.0 software was used to test the heterogeneity and evaluate the overall test performance. A total of 15 studies, including 1,225 patients, were included. The summary estimates of TP for CRC treated with 5-FU-based chemotherapy indicated a moderately positive prognosis with a hazard ratio (HR) of 0.76 (P=0.031) for overall survival and a HR of 0.711 (P=0.022) for relapse-free survival. On the basis of the present meta-analysis, TP could be promising and meaningful in the prognosis of CRC treated with 5-FU-based chemotherapy.

Analysis of Pelagia noctiluca proteome Reveals a Red Fluorescent Protein, a Zinc Metalloproteinase and a Peroxiredoxin

Pelagia noctiluca is the most venomous jellyfish in the Mediterranean Sea where it forms dense blooms. Although there is several published research on this species, until now none of the works has been focused on a complete protein profile of the all body constituents of this organism. Here, we have performed a detailed proteomics characterization of the major protein components expressed by P. noctiluca. With that aim, we have considered the study of jellyfish proteins involved in defense, body constituents and metabolism, and furthered explore the significance and potential application of such bioactive molecules. P. noctiluca body proteins were separated by1D SDS-PAGE and 2DE followed by characterization by nanoLC-MS/MS and MALDI-TOF/TOF techniques. Altogether, both methods revealed 68 different proteins, including a Zinc Metalloproteinase, a Red Fluorescent Protein (RFP) and a Peroxiredoxin. These three proteins were identified for the first time in P. noctiluca. Zinc Metalloproteinase was previously reported in the venom of other jellyfish species. Besides the proteins described above, the other 65 proteins found in P. noctiluca body content were identified and associated with its clinical significance. Among all the proteins identified in this work we highlight: Zinc metalloproteinase, which has a ShK toxin domain and therefore should be implicated in the sting toxicity of P. noctiluca.; the RFP which are a very important family of proteins due to its possible application as molecular markers; and last but not least the discovery of a Peroxiredoxin in this organism makes it a new natural resource of antioxidant and anti-UV radiation agents.

Molecular profile of 5-fluorouracil pathway genes in colorectal carcinoma

Background

This study addresses involvement of major 5-fluorouracil (5-FU) pathway genes in the prognosis of colorectal carcinoma patients.

Methods

Testing set and two validation sets comprising paired tumor and adjacent mucosa tissue samples from 151 patients were used for transcript profiling of 15 5-FU pathway genes by quantitative real-time PCR and DNA methylation profiling by high resolution melting analysis. Intratumoral molecular profiles were correlated with clinical data of patients. Protein levels of two most relevant candidate markers were assessed by immunoblotting.

Results

Downregulation of DPYD and upregulation of PPAT, UMPS, RRM2, and SLC29A1 transcripts were found in tumors compared to adjacent mucosa in testing and validation sets of patients. Low RRM2 transcript level significantly associated with poor response to the first-line palliative 5-FU-based chemotherapy in the testing set and with poor disease-free interval of patients in the validation set irrespective of 5-FU treatment. UPP2 was strongly methylated while its transcript absent in both tumors and adjacent mucosa. DPYS methylation level was significantly higher in tumor tissues compared to adjacent mucosa samples. Low intratumoral level of UPB1 methylation was prognostic for poor disease-free interval of the patients (P = 0.0002). The rest of the studied 5-FU genes were not methylated in tumors or adjacent mucosa.

Conclusions

The observed overexpression of several 5-FU activating genes and DPYD downregulation deduce that chemotherapy naïve colorectal tumors share favorable gene expression profile for 5-FU therapy. Low RRM2 transcript and UPB1 methylation levels present separate poor prognosis factors for colorectal carcinoma patients and should be further investigated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2826-8) contains supplementary material, which is available to authorized users.