Role of Genomic Markers in Colorectal Cancer Treatment

Integrated analysis reveals a novel 5-fluorouracil resistance-based prognostic signature with promising implications for predicting the efficacy of chemotherapy and immunotherapy in patients with colorectal cancer

BACKGROUND

5-Fluorouracil (5-FU) has been used as a standard first-line treatment for colorectal cancer (CRC) patients. Although 5-FU-based chemotherapy and immune checkpoint blockade (ICB) have achieved success in treating CRC, drug resistance and low response rates remain substantial limitations. Thus, it is necessary to construct a 5-FU resistance-related signature (5-FRSig) to predict patient prognosis and identify ideal patients for chemotherapy and immunotherapy.

METHODS

Using bulk and single-cell RNA sequencing data, we established and validated a novel 5-FRSig model using stepwise regression and multiple CRC cohorts and evaluated its associations with the prognosis, clinical features, immune status, immunotherapy, neoadjuvant therapy, and drug sensitivity of CRC patients through various bioinformatics algorithms. Unsupervised consensus clustering was performed to categorize the 5-FU resistance-related molecular subtypes of CRC. The expression levels of 5-FRSig, immune checkpoints, and immunoregulators were determined using quantitative real-time polymerase chain reaction (RT‒qPCR). Potential small-molecule agents were identified via Connectivity Map (CMap) and molecular docking.

RESULTS

The 5-FRSig and cluster were confirmed as independent prognostic factors in CRC, as patients in the low-risk group and Cluster 1 had a better prognosis. Notably, 5-FRSig was significantly associated with 5-FU sensitivity, chemotherapy response, immune cell infiltration, immunoreactivity phenotype, immunotherapy efficiency, and drug selection. We predicted 10 potential compounds that bind to the core targets of 5-FRSig with the highest affinity.

CONCLUSION

We developed a valid 5-FRSig to predict the prognosis, chemotherapeutic response, and immune status of CRC patients, thus optimizing the therapeutic benefits of chemotherapy combined with immunotherapy, which can facilitate the development of personalized treatments and novel molecular targeted therapies for patients with CRC.

LncRNA GAS6-AS1 contributes to 5-fluorouracil resistance in colorectal cancer by facilitating the binding of PCBP1 with MCM3

5-Fluorouracil (5-FU) resistance has always been a formidable obstacle in the adjuvant treatment of advanced colorectal cancer (CRC). In recent years, long non-coding RNAs have emerged as key regulators in various pathophysiological processes including 5-FU resistance. TRG is a postoperative pathological score of the chemotherapy effectiveness for CRC, of which TRG 0-1 is classified as chemotherapy sensitivity and TRG 3 as chemotherapy resistance. Here, RNA-seq combined with weighted gene correlation network analysis confirmed the close association of GAS6-AS1 with TRG. GAS6-AS1 expression was positively correlated with advanced clinicopathological features and poor prognosis in CRC. GAS6-AS1 increased the 50% inhibiting concentration of 5-FU, enhanced cell proliferation and accelerated G1/S transition, both with and without 5-FU, both in vitro and in vivo. Mechanistically, GAS6-AS1 enhanced the stability of MCM3 mRNA by recruiting PCBP1, consequently increasing MCM3 expression. Furthermore, PCBP1 and MCM3 counteracted the effects of GAS6-AS1 on 5-FU resistance. Notably, the PDX model indicated that combining chemotherapeutic drugs with GAS6-AS1 knockdown yielded superior outcomes in vivo. Together, our findings elucidate that GAS6-AS1 directly binds to PCBP1, enhancing MCM3 expression and thereby promoting 5-FU resistance. GAS6-AS1 may serve as a robust biomarker and potential therapeutic target for combination therapy in CRC.

Protein Kinase D1 Correlates with Less Lymph Node Metastasis Risk, Enhanced 5-FU Sensitivity, and Better Prognosis in Colorectal Cancer

Protein kinase D1 (PKD1) controls tumor growth and invasion of gastrointestinal tract-related cancers, but its prognostic role in colorectal cancer (CRC) is not clear yet. Therefore, this research intended to assess the potential of PKD1 as a marker for CRC patients' management, also to evaluate its effect on 5-fluorouracil (5-FU) chemosensitivity in CRC cell lines. PKD1 protein and mRNA expressions were measured by immunohistochemistry and reverse transcription-quantitative polymerase chain reaction assays in 214 CRC patients, respectively. The PKD1 overexpression plasmids and negative control (NC) plasmids were transfected into the HCT-116 and LoVo cell lines followed by 0-16 μM 5-FU treatment. PKD1 protein (P < 0.001) and mRNA expressions (P < 0.001) were both descended in tumor tissues compared to tumor-adjacent tissues. Meanwhile, tumor PKD1 protein and mRNA expressions were both negatively related to lymph node metastasis, N stage, and tumor-node-metastasis (TNM) stage (all P < 0.05). Prognostically, high expressions of PKD1 protein and mRNA were linked with prolonged disease-free survival (DFS) and overall survival (OS) (all P < 0.05). After adjustment by multivariate Cox analyses, PKD1 mRNA high expression independently forecasted longer DFS [hazard ratio (HR) = 0.199, P = 0.002] and OS (HR = 0.212, P = 0.022). In vitro experiments revealed that PKD1 overexpression decreased the half maximal inhibitory concentration value of 5-FU in the HCT-116 (P = 0.016) and LoVo (P = 0.007) cell lines. PKD1 expression links with less lymph node metastasis risk and satisfied prognosis in CRC patients, which promotes CRC cell chemosensitivity to 5-FU chemosensitivity as well.

SCG2: A Prognostic Marker That Pinpoints Chemotherapy and Immunotherapy in Colorectal Cancer

Background

Fluorouracil (FU)-based chemotherapy regimens are indispensable in the comprehensive treatment of colorectal cancer (CRC). However, the heterogeneity of treated individuals and the severe adverse effects of chemotherapy results in limited overall benefit.

Methods

Firstly, Weighted gene co-expression network analysis (WGCNA) identified modules tightly associated with chemotherapy response. Then, the in-house cohort and prognostic cohorts from TCGA and GEO were subjected to Cox proportional hazards model and survival analysis to ascertain the predictable function of SCG2 on the prognosis of CRC patients. Finally, we performed In vitro experiments, functional analysis, somatic mutation, and copy number variation research to explore the biological characteristics of SCG2.

Results

We identified red and green as the modules most associated with chemotherapy response, in which SCG2 was considered a risky factor with higher expression predicting poorer prognosis. SCG2 expression in the APC non-mutation group was remarkably higher than in the mutation group. The mutation frequencies of amplified genes differed significantly between different SCG2 expression subgroups. Besides, CRC cell lines with SCG2 knockdown have reduced invasive, proliferative, and proliferative capacity. We discovered that the SCG2 high expression subgroup was the immune hot type and considered more suitable for immunotherapy.

Conclusion

This study demonstrates the clinical significance and biological characteristics of SCG2, which could serve as a promising biomarker to identify patients who may benefit from chemotherapy and immunotherapy.

Role of N6-Methyladenosine Methylation Regulators in the Drug Therapy of Digestive System Tumours

Digestive system tumours, including stomach, colon, esophagus, liver and pancreatic tumours, are serious diseases affecting human health. Although surgical treatment and postoperative chemoradiotherapy effectively improve patient survival, current diagnostic and therapeutic strategies for digestive system tumours lack sensitivity and specificity. Moreover, the tumour's tolerance to drug therapy is enhanced owing to tumour cell heterogeneity. Thus, primary or acquired treatment resistance is currently the main hindrance to chemotherapy efficiency. N6-methyladenosine (m6A) has various biological functions in RNA modification. m6A modification, a key regulator of transcription expression, regulates RNA metabolism and biological processes through the interaction of m6A methyltransferase ("writers") and demethylase ("erasers") with the binding protein decoding m6A methylation ("readers"). Additionally, m6A modification regulates the occurrence and development of tumours and is a potential driving factor of tumour drug resistance. This review systematically summarises the regulatory mechanisms of m6A modification in the drug therapy of digestive system malignancies. Furthermore, it clarifies the related mechanisms and therapeutic prospects of m6A modification in the resistence of digestive system malignancies to drug therapy.

Tumor-Associated Macrophages Promote Oxaliplatin Resistance via METTL3-Mediated m6A of TRAF5 and Necroptosis in Colorectal Cancer

As a third-generation platinum drug, oxaliplatin (OX) is widely used as the first-line chemotherapeutic agent in the treatment of colorectal cancer (CRC). CRC cells acquire resistance to chemotherapy and develop resistance, which is a major challenge for the treatment of advanced CRC. Recent studies have suggested that the therapeutic resistance of tumors is affected by the tumor microenvironment (TME). As a critical role among TME, tumor-associated macrophages (TAMs) play an important role. However, their regulatory mechanism underlying the drug resistance in CRC remains largely unknown. In the present study, we found that the density of macrophages infiltrated into the CRC tissues from OX-resistant patients was significantly higher compared with the OX-sensitive patients. Interestingly, both the total N⁶-methyladenosine (m⁶A) RNA content and the expression of its critical methyltransferase METTL3 were increased in the CRC tissues from OX-resistant patients compared with the OX-sensitive patients. Furthermore, we demonstrated that the M2-polarized TAMs enabled the OX resistance via the elevation of METTL3-mediated m⁶A modification in cells. Through whole-genome CRISPR screening and further validation, we found that TRAF5 contributes to the METTL3-triggered OX resistance in CRC cells. This study unveiled that M2-TAMs were important mediators for the acquisition of OX resistance. Furthermore, we provided evidence that targeting of M2-TAMs and METTL3-mediated m⁶A modification might be a promising adjuvant therapeutic strategy for CRC patients, especially for OX-resistant CRC patients.

Differential sensitization of two human colon cancer cell lines to the antitumor effects of irinotecan combined with 5-aza-2'-deoxycytidine

Irinotecan (CPT-11) is a key therapeutic drug used in the treatment of colorectal cancer, although acquired or constitutive resistance to CPT-11 (and its activated metabolite SN-38) can lead to tumor progression. Since the acquisition of drug resistance can result from DNA hypermethylation, the antitumor activity of CPT-11 and SN-38 was assessed in combination with a known DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, also known as decitabine (DAC). DAC potentiated the antitumor activity of CPT-11 additively, and that of SN-38 synergistically, as measured by colony formation in the human colorectal cancer HCT116 cell line. No DAC potentiation of these antitumor effects was observed with another human colorectal cancer HT29 cell line. Anti-apoptotic B-cell lymphoma-2 (Bcl-2) protein expression was reduced to 50-67% of the control following a single treatment with CPT-11, SN-38, or DAC, and was markedly reduced to 7-8% following the combination of CPT-11/SN-38 with DAC. By contrast, Bcl-2 protein expression was barely detected in HT29. Wilms' tumor protein (WT1), which has been shown to be a positive regulator of Bcl-2 in HCT116 cells through WT1-kncokdown experiments, was downregulated in HCT116 and HT29 cells when treated with CPT-11/SN-38 combined with DAC, with decreases greater than any single administration of CPT-11, SN-38, or DAC. The extent of CPT-11/SN-38 potentiation by DAC may depend on Bcl-2 expression levels in human colorectal cancer cells.

Elevated CA19-9 as the Most Significant Prognostic Factor in Locally Advanced Rectal Cancer Following Neoadjuvant Chemoradiotherapy

It remains controversial regarding the prognostic significance of carbohydrate antigen 19-9 (CA19-9) for locally advanced rectal cancer (LARC) (T3-4/N+) patients with neoadjuvant chemoradiotherapy (neo-CRT). And it is unknown whether CA19-9 can identify patients who may benefit from adjuvant chemotherapy.Overall, 303 LARC patients with neo-CRT between 2004 and 2010 were recruited. Overall survival (OS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and local recurrence-free survival across pretreatment CA19-9 were estimated by Kaplan-Meier method and Cox regression model.In univariate analysis, elevated CA19-9 (>35 U/mL) was significantly correlated with poor OS (P = 0.003), DFS (P = 0.001), and DMFS (P = 0.039). Adjusting for the known covariates, CA19-9 was significantly associated with OS (HR = 1.86, 95% CI 1.03-3.34, P = 0.039) and DFS (HR = 1.74, 95% CI 1.08-2.80, P = 0.024). In the elevated CA19-9 subgroup, patients with adjuvant chemotherapy got much better OS (P < 0.001) and DFS (P = 0.016) than those without. In consideration of both CA19-9 and carcinoembryonic antigen (CEA), we found that patients with both elevated CA19-9 and CEA (>5 ng/mL) got the worst OS (P = 0.021) and DFS (P = 0.006), and significantly benefited from adjuvant chemotherapy in OS (P < 0.001) and DFS (P = 0.026).Pretreatment CA19-9 level is a significant prognostic indicator in patients with LARC following neo-CRT. The addition of CA19-9 to CEA is valuable to discriminate the appropriate patients for adjuvant chemotherapy.

Association of GSTP1 and RRM1 Polymorphisms with the Response and Toxicity of Gemcitabine-cisplatin Combination Chemotherapy in Chinese Patients with Non-small Cell Lung Cancer

BACKGROUND

Previous studies showed that genetic polymorphisms of glutathione S-transferase P1 (GSTP1) were involved in glutathione metabolism and genetic polymorphisms of ribonucleotide reductase (RRM1) were correlated with DNA synthesis. Here we explored the effects of these polymorphisms on the chemosensitivity and clinical outcome in Chinese non-small cell lung cancer (NSCLC) patients treated with gemcitabine-cisplatin regimens.

MATERIALS AND METHODS

DNA sequencing was used to evaluate genetic polymorphisms of GSTP1 Ile105Val and RRM1 C37A-T524C in 47 NSCLC patients treated with gemcitabine-cisplatin regimens. Clinical response was evaluated according to RECIST criteria after 2 cycles of chemotherapy and toxicity was assessed by 1979 WHO criteria (acute and subacute toxicity graduation criteria in chemotherapeutic agents).

RESULTS

There was no statistical significance between sensitive and non-sensitive groups regarding the genotype frequency distribution of GSTP1 Ile105Val polymorphism (p>0.05). But for RRM1 C37A-T524C genotype, sensitive group had higher proportion of high effective genotype than non-sensitive group (p=0.009). And according to the joint detection of GSTP1 Ile105Val and RRM1 C37A-T524C polymorphisms, the proportion of type A (A/A+high effective genotype) was significantly higher in sensitive group than in non-sensitive group (p=0.009). Toxicity showed no correlation with the genotypes between two groups (p>0.05).

CONCLUSIONS

Compared with single detection of genetic polymorphisms of GSTP1 Ile105Val or RRM1 C37A-T524C, joint detection of both may be more helpful for patients with NSCLC to receive gemcitabine-cisplatin regimens as the first-line chemotherapy. Especially, genetic polymorphism of RRM1 is more likely to be used as an important biomarker to predict the response and toxicity of gemcitabine-cisplatin combination chemotherapy in NSCLC.

Metallothionein 1G and zinc sensitize human colorectal cancer cells to chemotherapy

Metallothioneins (MT) are a family of low molecular weight proteins that are silenced during colorectal cancer progression, mainly through epigenetic mechanisms, and this loss is associated with poor survival. In this article, we show that overexpression of the MT1G isoform sensitizes colorectal cell lines to the chemotherapeutic agents oxaliplatin (OXA) and 5-fluorouracil (5-FU), in part through enhancing p53 and repressing NF-κB activity. Despite being silenced, MTs can be reinduced by histone deacetylase inhibitors such as trichostatin A and sodium butyrate. In fact, this induction contributes to the cytotoxicity of these agents, given that silencing of MTs by siRNAs reduces their growth-inhibitory activities. Zinc ions also potently enhance MT expression and are cytotoxic to cancer cells. We show for the first time that OXA and 5-FU induce higher levels of intracellular labile zinc, as measured using the fluorescent probe FLUOZIN-3, and that such zinc contributes to the activation of p53 and repression of NF-κB. Addition of zinc enhanced growth inhibition by OXA and 5-FU, and was also capable of resensitizing 5-FU-resistant cell lines to levels comparable with sensitive cell lines. This effect was MT independent because silencing MTs did not affect zinc cytotoxicity. In conclusion, we show that MT induction and zinc administration are novel strategies to sensitize colorectal cancer cells to presently utilized chemotherapeutic agents.

Clinical-Pathological Correlation of KRAS Mutation Status in Metastatic Colorectal Adenocarcinoma

Background

KRAS gene mutations play an important role in the carcinogenesis of colorectal tumors. However, studies that have assessed the association between KRAS gene mutation status and disease characteristics report conflicting results. To assess KRAS gene status (mutated or wild-type) and its association with the clinical, epidemiological, and histopathological features of metastatic colorectal adenocarcinoma as well its association with clinical outcomes.

Methods

Cross-sectional descriptive study in which clinical and histopathological data were collected from the medical records of 65 patients diagnosed with metastatic colorectal adenocarcinoma at the Clinical Oncology Service of the Teaching Hospital of the School of Medicine of Ribeirao Preto, University of Sao Paulo (Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo -HCFMRP-USP) between 2005 and 2012 and analyzed based on their KRAS gene status.

Results

KRAS gene mutations were found in 49.2% of the tumors, and G/A (25.5%) and Gly12Asp (34.37%) were the most frequent mutations. Among the investigated clinical features (gender, ECOG (Eastern Cooperative Oncology Group), histology, degree of cell differentiation, lymph node ratio, primary tumor site, staging, presence of synchronous metastasis, lung metastasis, and liver metastasis), the association between age less than 65 years with KRAS mutation was statistically significant (P = 0.046). KRAS mutation status did not exhibit a significant correlation with the overall survival of the patients (P = 0.078); however, the cases with KRAS mutation exhibited shorter survival. In the multivariate analysis, synchronous metastasis (P = 0.03) and liver metastasis (P = 0.008) behaved as independent factors of poor prognosis relative to the overall survival of the patients.

Conclusion

The KRAS mutation status did not exhibit prognostic value in the investigated sample. Among the older patients (> 65 years old), wild-type KRAS was more frequently observed compared to mutated KRAS.

Long-term results of 2 adjuvant trials reveal differences in chemosensitivity and the pattern of metastases between colon cancer and rectal cancer

Two identical randomized controlled trials designed to optimize adjuvant treatment of colon cancer (CC) (n =855) and rectal cancer (RC) (n = 796) were performed. Long-term evaluation confirmed that the addition of folinic acid (FA) to 5-fluorouracil (5-FU) improved 7-year overall survival (OS) in CC but not in RC and revealed different patterns of recurrence in patients with CC and those with RC.

BACKGROUND

Our aim was to compare long-term results of adjuvant treatment of colon cancer (CC) and rectal cancer (RC). Adjuvant chemotherapy of CC improved overall survival (OS), whereas that of RC remained at the level achieved by 5-fluorouracil (5-FU).

METHODS

We separately conducted 2 identically designed adjuvant trials in CC and RC. Patients were assigned to adjuvant chemotherapy with 5-FU alone, 5-FU + folinic acid (FA), or 5-FU + interferon-alfa. The first study enrolled patients with stage IIb/III CC, and the second study enrolled patients with stage II/III RC. All patients with RC received postoperative irradiation.

RESULTS

Median follow-up for all patients with CC (n = 855) and RC (n = 796) was 4.9 years. The pattern and frequency of recurrence differed significantly, especially lung metastases, which occurred more frequently in RC (12.7%) than in CC (7.3%; P < .001). Seven-year OS rates for 5-FU, 5-FU + FA, and 5-FU + IFN-alfa were 54.1% (95% confidence interval [CI], 46.5-61.0), 66.8% (95% CI, 59.4-73.1), and 56.7% (95% CI, 49.3-63.4) in CC and 50.6% (95% CI, 43.0-57.7), 56.3% (95% CI, 49.4-62.7), and 54.8% (95% CI, 46.7-62.2) in RC, respectively. A subgroup analysis pointed to a reduced local recurrence (LR) rate and an increased OS by the addition of FA in stage II RC (n = 271) but not in stage III RC (n = 525).

CONCLUSION

FA increased 7-year OS by 12.7 percentage points in CC but was not effective in RC. Based on these results and the pattern of metastases, our results suggest that the chemosensitivity of CC and RC may be different. Strategies different from those used in CC may be successful to decrease the frequency of distant metastases in RC in the future.

Bax expression is a candidate prognostic and predictive marker of colorectal cancer

OBJECTIVE

Since the anti-tumor activity of 5-fluorouracil (5-FU) is due to induction of apoptosis, we assessed the value of expression of key apoptotic molecules (Bax, Bcl-2 and p53) in predicting the efficacy of 5-FU therapy for colorectal adenocarcinomas (CRCs).

METHODS

Archival tissues of CRCs from 56 patients who received a complete regimen of 5-FU-based chemotherapy after surgery, and 56 patients matched for age, gender, ethnicity, tumor stage, tumor location, and tumor differentiation who had undergone only surgery (without any pre- or post-surgery therapy), were evaluated for immunophenotypic expression of Bax, Bcl-2, and p53. Also, these CRCs were evaluated for Bax mutations. The predictive capacity or prognostic value of these markers was assessed by estimating overall survival.

RESULTS

The majority of low Bax expressing CRCs have exhibited mutations at the G (8) tract. There was no significant difference in overall survival rates between the categories of surgery alone and 5-FU-treated patients. However, a better survival was observed for patients who received chemotherapy when their CRCs had low Bax/Bcl2 ratio (HR, 1.55; 95% CI: 1.46-31.00). Patients who received surgery alone and whose CRCs lacked Bax expression had 5.33 times higher mortality than those with high Bax expression (95% CI: 1.78-15.94), when controlled for tumor stage and other confounders. Bcl-2 and nuclear p53 accumulation had no predictive value in either patient group.

CONCLUSION

These findings are the first to demonstrate that high Bax expression is a good prognosticator for patients who underwent surgery alone, and that patient with low Bax/Bcl-2 expression ratio benefit from 5-FU-based adjuvant therapies.

Notch1 and Notch2 have opposite prognostic effects on patients with colorectal cancer

BACKGROUND

Aberrantly activated Notch signaling has been shown to play a key role in carcinogenesis and progression of various human malignancies. In this study, we investigated the expression of Notch1 and Notch2 in colorectal cancer to determine whether they could serve as prognostic predictors.

PATIENTS AND METHODS

The protein expression of Notch1 and Notch2 was examined by immunohistochemistry in 1003 clinical colorectal cancer specimens. Notch1 and Notch2 protein levels were investigated by immunohistochemistry. Statistical analysis was carried out to assess their prognostic value.

RESULTS

Significantly negative correlation between Notch1 and Notch2 was found in colorectal cancer (P < 0.001). Notch1 and Notch2 were proved to be inversely correlated with tumor differentiation, depth of invasion, lymph node metastases, distant metastasis, TNM (tumor-node-metastasis) stage and survival of patients, suggesting opposite function of the two receptors. Notch1 and Notch2 were proved to be adverse independent prognostic predictors (P < 0.001). Moreover, a synergistic effect of positive Notch1 and negative Notch2 coexpression on predicting poor overall survival was proved.

CONCLUSIONS

Notch1 and Notch2 may be independent adverse prognostic predictors for patients with colorectal cancer. These results would contribute to identify more efficient prognostic predictors and therapeutic targets.

Adjuvant chemoradiotherapy of advanced resectable rectal cancer: results of a randomised trial comparing modulation of 5-fluorouracil with folinic acid or with interferon-α

BACKGROUND

Standard adjuvant chemoradiotherapy of rectal cancer still consists of 5-fluorouracil (5-FU) only. Its cytotoxicity is enhanced by folinic acid (FA) and interferon-α (INFα). In this trial, the effects of FA and IFNα on adjuvant 5-FU chemoradiotherapy in locally advanced rectal cancer were investigated.

METHODS

Patients with R(0)-resected rectal cancer (UICC stage II and III) were stratified and randomised to a 12-month adjuvant chemoradiotherapy with 5-FU, 5-FU+FA, or 5-FU+IFNα. All patients received levamisol and local irradiation with 50.4 Gy.

RESULTS

Median follow-up was 4.9 years (n=796). Toxicities (WHO III+IV) were observed in 32, 28, and 58% of patients receiving 5-FU, 5-FU+FA, and 5-FU+IFNα, respectively. No differences between the groups were observed for local or distant recurrence. Five-year overall survival (OS) rates were 60.3% (95% confidence interval (CI): 54.3-65.8), 60.4% (54.4-65.8), and 59.9% (53.0-66.1) for 5-FU, 5-FU+FA, and 5-FU+IFNα, respectively. A subgroup analysis in stage II (pT3/4pN0) disease (n=271) revealed that the addition of FA tended to reduce the 5-year local recurrence (LR) rate by 55% and increase recurrence-free survival and OS rates by 12 and 13%, respectively, relative to 5-FU alone.

CONCLUSIONS

Interferon-α cannot be recommended for adjuvant chemoradiotherapy of rectal cancer. In UICC stage II disease, the addition of FA tended to lower LR and increased survival. The addition of FA to 5-FU may be an effective option for adjuvant chemoradiotherapy of UICC stage II rectal cancer.

Mismatch repair protein expression is an independent prognostic factor in sporadic colorectal cancer

Abstract Background. Mismatch repair (MMR) status has been reported as a prognostic and predictive factor in sporadic colorectal cancer (CRC). The purpose of this study was to determine the prognostic and predictive value of MMR protein expression in the adjuvant setting. Patients and methods. The MMR status in the primary tumor was retrospectively assessed on paraffin-embedded formalin-fixed samples from 1 006 patients with sporadic CRC (488 stage II and 518 stage III) using immunohistochemical analysis (IHC) of MLH1 and MSH2 expression. The patients were included in adjuvant Nordic trials between 1991 and 1996 randomly assigned to surgery alone or surgery plus adjuvant 5-fluorouracil (5-FU)-based chemotherapy. Data was censored at 120 months after surgery. Results. One hundred fifty-seven patients (15.6%) showed a loss of MMR protein expression (139 MLH1 negative, 15 MSH2 negative and 3 MLH1 and MSH2 negative) and were classified as MMR protein negative. A normal MMR protein expression was found in 849 patients who were defined as MMR protein positive. MMR protein expression was a significant prognostic marker in the entire study group with a better overall survival (OS) among patients with MMR protein negative tumors compared to patients with MMR protein positive tumors (p=0.01). In a multivariate analysis the MMR protein expression was significantly associated with OS, (HR 0.70 [95% CI, 0.40 to 0.99]; p=0.01). The MMR status did not predict survival benefit from adjuvant 5-FU-based chemotherapy. Conclusion. This study reveals that IHC of MLH1 and MSH2 expression can yield important prognostic information but is not a predictive factor for adjuvant 5-FU-based chemotherapy in sporadic CRC.

The synergistic effect of recombinant human endostatin (YH-16) combined with oxaliplatin on human colorectal carcinoma

This study was designed to investigate the effect of recombinant human endostatin (YH-16) combined with oxaliplatin (L-OHP) on the growth of orthotopically-implanted human colorectal carcinoma in nude mice. Tumour volumes and weights were measured after therapy. Tumour cell morphology was observed by light and electron microscopy. Apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) assay, and vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) were determined by immunohistochemical staining. Tumour volumes in all treatment groups were significantly reduced compared with controls. YH-16 and L-OHP either alone or in combination caused tumour cell apoptosis, except in the YH-16 low-dose group. MVD was strongly inhibited in the treatment groups compared with the controls, although only YH-16 combined with L-OHP or L-OHP alone decreased VEGF expression. No obvious change in side-effects occurred. In conclusion, YH-16 combined with L-OHP inhibited growth and induced apoptosis in orthotopically-transplanted human colorectal carcinoma in nude mice without increasing side-effects.

Genetic polymorphism of GSTP1: prediction of clinical outcome to oxaliplatin/5-FU-based chemotherapy in advanced gastric cancer

The aim of this study was to evaluate the predictive value of the polymorphism Glutathione S-transferase P1 (GSTP1) Ile(105)Val on oxaliplatin/5-FU-based chemotherapy in advanced gastric cancer. Patients with advanced gastric cancer accepted oxaliplatin/5-FU-based chemotherapy as first-line chemotherapy were investigated. GSTP1 Ile(105)Val polymorphism was detected by TaqMan-MGB probe allelic discrimination method. Response to treatment was assessed by disease controlled rate. Time to progression, overall survival and toxicities were recorded. Final patient outcomes were as follows: the allele frequencies of GSTP1 were (105)Ile/(105)Ile 52%, (105)Ile/(105)Val 41% and (105)Val/(105)Val 7%. For patients with (105)Ile/(105)Ile and those with at least one (105)Val allele, disease control rate was 39% and 71% (P=0.026), respectively; median time to progression was 4.0 and 7.0 months (P=0.002); median overall survival time was 7.0 and 9.5 months (P=0.002). Neurological toxicity was more frequently occurred in patients with two (105)Ile alleles (P=0.005). In conclusion, patients with at least one (105)Val allele have better prognosis and response to oxaliplatin/5-FU-based regimen as first-line treatment for patients with advanced gastric cancer.

Clinical biomarkers in oncology: focus on colorectal cancer

Rapidly growing insight into the molecular biology of colorectal cancer has led to high hopes for the identification of molecular markers to be used in optimized and tailored treatment regimens. However, many of the published data on gene-specific biomarkers are contradictory in their findings, and no tests are currently used in clinical practice, with the exception of microsatellite instability (MSI) and guanylyl cyclase C (GCC) testing in the adjuvant setting, and in Europe KRAS mutation testing is used in the setting of epidermal growth factor receptor (EGFR)-targeted therapy for metastatic disease. There are many reasons for the failure of the initial marker hypothesis-driven approach. Although supported by a good biologic rationale, single markers such as tumor protein p53 (TP53) gene mutations, when applied to a complex tumor type containing many synchronous alterations, do not perform well in predicting outcome. Many markers also suffer from technical shortcomings, resulting from the lack of quantitative techniques to capture the impact of the molecular alteration. The impact of markers obtained from microarray expression profiling needs to be further investigated in studies based on much larger cohorts, and cross-validation studies will be essential. Recently, mutations in the KRAS gene were shown to be strong negative predictors of response to EGFR inhibitors in metastatic disease. It has also been suggested that BRAF gene mutations may be predictive of EGFR inhibitor resistance, and there are some conflicting data regarding the role of the PIK3CA gene. Further studies are needed to help integrate the latest findings into clinically useful tools for personalized medicine.

Epigenetic mechanisms of irinotecan sensitivity in colorectal cancer cell lines

Irinotecan is a topoisomerase-I (Top-I) inhibitor used for the treatment of colorectal cancer. DNA demethylating agents, including 5-azacytidine (5-aza), display synergistic antitumor activity with several chemotherapy drugs. 5-Aza may enhance irinotecan cytotoxicity by at least one of the following mechanisms: (a) Top-I promoter demethylation, (b) activation of genes involved in Top-I transcriptional regulation (p16 or Sp1), and (c) modulation of the cell cycle and apoptosis after DNA damage. The growth-inhibitory effects of SN38, the active metabolite of irinotecan, 5-aza, and their combinations, were studied in four colorectal cancer cell lines. The effects of treatments on cell cycle were analyzed by flow cytometry, and apoptosis was measured by fluorescence microscopy. Top-I, Sp1, and p53 expression modulated by 5-aza were measured by real-time PCR. Methylation of Top-I, p16, 14-3-3sigma, and hMLH1 promoters before and after 5-aza treatment were measured by MethyLight PCR and DNA bisulfite sequencing. Low-dose 5-aza significantly enhanced the apoptotic effect of irinotecan in all colorectal cancer cells, whereas a synergistic cytotoxic effect was observed only in p53-mutated cells (HT29, SW620, and WiDr). This synergistic effect was significantly correlated with Top-I up-regulation by 5-aza, and coupled to p16 demethylation and Sp1 up-regulation. p16 demethylation was also associated with enhanced cell cycle arrest after irinotecan treatment. In contrast, 5-aza down-regulated Top-I expression in the p53 wild-type LS174T cells in a p53-dependent manner, thereby reducing SN38 cytotoxicity. In conclusion, 5-aza modulates Top-I expression by several mechanisms involving Sp1, p16, and p53. If confirmed in other models, these results suggest that p16 and p53 status affects the 5-aza-irinotecan interaction.

Pharmacogenomics of Colorectal Cancer Prevention and Treatment

Pharmacogenomic tools are beginning to emerge that will provide guidance in the treatment and prevention of colorectal cancer. Significant individual genetic variation exists in drug metabolism of 5FU, capecitabine, irinotecan, and oxaliplatin that influences both the toxicity and efficacy of these agents. Recent FDA approval of genetic testing for mutations in the UGT1A1 gene that predict adverse reactions to irinotecan is ushering in a new era that will increasingly rely on genotyping to individualize treatment decisions for patients with cancer as well as for patients at high risk who may be candidates for chemoprevention agents. This review focuses on current knowledge regarding key mutations and polymorphisms which affect outcomes for colorectal cancer patients, as well as the pharmacogenetics of chemoprevention trials.

Decreased levels of UMP kinase as a mechanism of fluoropyrimidine resistance

5-Fluorouracil (5-FU) continues to be widely used for treatment of gastrointestinal cancers. Because many tumors show primary or acquired resistance, it is important to understand the molecular basis underlying the mechanism of resistance to 5-FU. In addition to its effect on thymidylate synthase inhibition and DNA synthesis, 5-FU may also influence RNA metabolism. Our previous studies revealed that colorectal cancer cells resistant to bolus 5-FU (HCT-8/4hFU) showed significantly decreased incorporation of the drug into RNA. Resistance to bolus 5-FU was associated with lower expression of UMP kinase (UMPK), an enzyme that plays an important role in the activation of 5-FU to 5-FUTP and its incorporation into RNA. Activities of other 5-FU-metabolizing enzymes (e.g., thymidine kinase, uridine phosphorylase, thymidine phosphorylase, and orotate phosphoribosyltransferase) remained unchanged between sensitive and resistant cell lines. Herein, we show that UMPK down-regulation in 5-FU-sensitive cells (HCT-8/P) induces resistance to bolus 5-FU treatment. Moreover, HCT-8/4hFU cells are even more cross-resistant to treatment with 5-fluorouridine, consistent with the current understanding of 5-fluorouridine as a RNA-directed drug. Importantly, colorectal cancer hepatic metastases isolated from patients clinically resistant to weekly bolus 5-FU/leucovorin treatment exhibited decreased mRNA expression of UMPK but not thymidylate synthase or dihydropyrimidine dehydrogenase compared with tumor samples of patients not previously exposed to 5-FU. Our findings provide new insights into the mechanisms of acquired resistance to 5-FU in colorectal cancer and implicate UMPK as an important mechanism of clinical resistance to pulse 5-FU treatment in some patients.

Identification of high-risk stage II colorectal tumors by combined analysis of the NDRG1 gene expression and the depth of tumor invasion

BACKGROUND

Experiments on cancer cell lines and animal models indicated that alteration in expression of N-myc down-regulated gene 1 (NDRG1) is associated with development of colon cancer. However, few clinical data are available to assess the role of NDRG1 in progression of human colorectal cancer. This study was undertaken to reveal the prognostic and predictive usefulness of NDRG1 expression determination in colorectal cancer.

METHODS

The expression of NDRG1 mRNA was investigated in 108 colorectal cancer tissues by real-time polymerase chain reaction. The level of NDRG1 protein was investigated by immunohistochemistry.

RESULTS

Patients with lowered level of NDRG1 mRNA had a statistically significantly shorter 5-year survival rate compared with patients with unchanged expression of NDRG1 (P = .01). The overall survival time for patients with II tumor, node, metastasis system (TNM) stage disease and tumors displaying reduced expression of NDRG1 was significantly shorter compared with patients with preserved NDRG1 expression (P = .024). Moreover, the survival rate of patients with TNM stage II disease and T4 lesion was significantly lower (P = .0005) for patients with reduced level of NDRG1 expression compared with patients with unchanged NDRG1 expression. The stepwise multivariate regression analysis revealed that advanced TNM stage and lowered NDRG1 expression level were independent unfavorable prognostic factors for patient survival.

CONCLUSIONS

The assessment of NDRG1 expression offers valuable prognostic information for patients with colorectal cancer, especially for those with stage II disease. We propose that NDRG1 expression level could be used to select patients with stage II disease who are at increased risk of unfavorable outcome, and who may benefit from adjuvant therapy.

Correlation Between Thymidylate Synthase Protein Expression and Gene Polymorphism with Clinicopathological Parameters in Colorectal Carcinoma

5-Fluorouracil (5-FU) represents the basis of chemotherapy for colorectal carcinoma, inhibiting thymidylate synthase (TS), an essential enzyme for DNA replication. Previous studies have associated high TS protein expression by tumor cells with poor outcome of patients with colorectal carcinoma, but others have refuted these findings. In view of the potential role of TS as predictive parameter and the lack of consensus in the literature, the present study compared 2 methods: protein expression and gene polymorphism, correlating them with clinicopathological findings. Immunohistochemical detection of TS in tumor cells and detection of gene polymorphism in the blood were performed in 32 patients with colorectal carcinoma treated with 5-FU. No correlation was found between TS protein expression and gene polymorphism. Neither method correlated with survival, tumor staging, and tumor histological grading. This result possibly reflects a complex tumor response to 5-FU therapy, where TS is just one of the involved proteins.

The role of molecular markers in predicting response to therapy in patients with colorectal cancer

Advances in systemic therapy for colorectal cancer have dramatically improved prognosis. While disease stage has traditionally been the main determinant of disease course, several molecular characteristics of tumor specimens have recently been shown to have prognostic significance. Although to date no molecular characteristics have emerged as consistent predictors of response to therapy, retrospective studies have investigated the role of a variety of biomarkers, including microsatellite instability, loss of heterozygosity of 18q, type II transforming growth factor beta receptor, thymidylate synthase, epidermal growth factor receptor, and Kirsten-ras (KRAS). This paper reviews the current literature, ongoing prospective studies evaluating the role of these markers, and novel techniques such as gene profiling, which may help to uncover the more complex molecular interactions that will predict response to chemotherapy in patients with colorectal cancer.

A role for VICKZ proteins in the progression of colorectal carcinomas: regulating lamellipodia formation

VICKZ proteins are a highly conserved family of RNA binding proteins, implicated in RNA regulatory processes such as intracellular RNA localization, RNA stability, and translational control. During embryogenesis, VICKZ proteins are required for neural crest migration and in adults, the proteins are overexpressed primarily in different cancers. We hypothesized that VICKZ proteins may play a role in cancer cell migration. In patients, VICKZ expression varies with tumour type, with over 60% of colon, lung, and ovarian tumours showing strong expression. In colorectal carcinomas (CRCs), expression is detected at early stages, and the frequency and intensity of staining increase with progression of the disease to lymph node metastases, of which 97% express the protein at high levels. Indeed, in stage II CRC, the level of VICKZ expression in the primary lesion correlates with the degree of lymph node metastasis. In culture, VICKZ proteins rapidly accumulate in processes at the leading edge of PMA-stimulated SW480 CRC cells, where they co-localize with beta-actin mRNA. Two distinct cocktails of shRNAs, each targeting all three VICKZ paralogues, cause a dramatic drop in lamellipodia and ruffle formation in stimulated cells. Thus, VICKZ proteins help to facilitate the dynamic cell surface morphology required for cell motility. We propose that these proteins play an important role in CRC metastasis by shuttling requisite RNAs to the lamellipodia of migrating cells.

Development of a clinically feasible molecular assay to predict recurrence of stage II colon cancer

The 5-year survival rate for patients with Stage II colon cancer is approximately 75%. However, there is no clinical test available to identify the 25% of patients at high risk of recurrence. We have previously identified a 23-gene signature that predicts individual risk for recurrence. The present study tested this gene signature in an independent group of 123 Stage II patients, and the 23-gene signature was highly informative in identifying patients with distant recurrence in both univariate (hazard ratio [HR] 2.51) and multivariate analyses (HR, 2.40). The composition of this representative patient group also allowed us to refine the 23-gene signature to a 7-gene signature that exhibited a similar prognostic power in both univariate (HR, 2.77) and multivariate analyses (HR, 2.87). Furthermore, we developed this prognostic signature into a clinically feasible test with real-time quantitative PCR using standard fixed paraffin-embedded tumor tissues. When a 110-patient cohort was evaluated with the PCR assay, the 7-gene signature, demonstrated to be a strong prognostic factor in both univariate (HR, 6.89) and multivariate analyses (HR, 14.2). These results clearly show the prognostic value of the predefined gene signature for Stage II colon cancer patients. The ability to identify colon cancer patients with an unfavorable outcome may help patients at high risk for recurrence to seek more aggressive therapy.

UGT1A1*28 polymorphism predicts irinotecan-induced severe toxicities without affecting treatment outcome and survival in patients with metastatic colorectal carcinoma

BACKGROUND

It is known that the uridine-diphosphoglucuronosyl transferase 1A1 (UGT1A1)*28 polymorphism reduces UGT1A1 enzyme activity, which may lead to severe toxicities in patients who receive irinotecan. This study was conducted to assess the influence of this polymorphism on the efficacy and toxicity of irinotecan treatment in Chinese patients with metastatic colorectal carcinoma (CRC).

METHODS

In total, 128 patients with metastatic CRC who had received previous treatment with irinotecan plus 5-fluorouracil/leucovorin were analyzed retrospectively. Genomic DNA samples were obtained from patients' leukocytes, and genotypes were determined by analyzing the sequence of TATA boxes in the UGT1A1 gene. The influence of the UGT1A1*28 polymorphism on toxicity and treatment outcome was analyzed.

RESULTS

Approximately 20% of patients were identified with the UGT1A1*28 polymorphism, including 15.6% (n = 20 patients) with the thymine-adenine (TA)6/TA7 genotype and 4.7% (n = 6 patients) with the TA7/TA7 genotype. The remaining 79.7% of patients (n = 102) had wild type TA6/TA6. Marked increases in grade 3 or 4 neutropenia (53.8% vs 4.9%; P < .01), neutropenic fever (38.5% vs 3.9%; P < .01), diarrhea (26.9% vs 5.9%; P < .01), and pretreatment bilirubin level (23.1% vs 8.8%; P = .04) were observed in patients who had the TA6/TA7 or TA7/TA7 genotypes. Patients' pretreatment bilirubin levels correlated well with irinotecan-induced neutropenia (P < .01). It was noted that, although the requirement for irinotecan dose reduction was significantly greater in patients who had this genetic variant (42.3% vs 12.7%; P < .01), it did not affect the response rate to irinotecan-based chemotherapy (42.3% vs 45.1%; P = .80), and it did not significantly affect progression-free survival (10 months vs 11 months; P = .94) or overall survival (19 months vs 18 months; P = .84).

CONCLUSIONS

The current data suggested that the UGT1A1*28 polymorphism may be a key determinant for predicting irinotecan-induced severe toxicities without affecting treatment outcome for patients with metastatic CRC. Further prospective studies are warranted for using this polymorphism to optimize irinotecan-based chemotherapy.

Understanding genomics: no longer optional for gastroenterology nurses

National news was made in 2003 with an amazing accomplishment: the completion of the Human Genome Project. This landmark endeavor produced a human DNA blueprint that helps scientists identify disease-causing genes and DNA variations affecting health promotion, disease prevention, and treatment responses. In October 2007, the Society of Gastroenterology Nurses and Associates joined the American Nurses Association and 48 other nursing organizations endorsing the document Essential Nursing Competencies and Curricula Guidelines for Genetics and Genomics. This document describes the minimum essential genetic/genomic competencies for all registered nurses regardless of education, practice role, or specialty area. How do these two pivotal events--mapping the human genome and establishing genetic/genomic nursing competencies--interface with each other and with gastroenterology nursing practice? This article defines genetics and genomics; discusses associated terminology and technology; and relates information to hereditary, familial, and sporadic colon cancer. Two case studies highlight essential nursing competencies, the genetic concepts of hereditary colon cancer, and the genomic aspects of sporadic colon cancer. A genomics glossary and a Web site resource chart for nurses and clients are included. The author shows how genetics and genomics are relevant for today's gastroenterology nurse.

The multidisciplinary management of gastrointestinal cancer. The use of molecular markers in the diagnosis and treatment of colorectal cancer

Rapidly growing insights into the molecular biology of colorectal cancer led to high hopes for the identification of molecular markers to be used in optimised and tailored treatment regimens for this disorder. However, no molecular marker has yet made it into daily practice. In this review we will discuss some of the potential molecular markers, focus on the lessons learnt from marker development and identify strategies for the future.

Epidermal growth factor receptor R497K polymorphism is a favorable prognostic factor for patients with colorectal carcinoma

PURPOSE

It has been shown that the R497K polymorphism of the epidermal growth factor receptor (EGFR) has attenuated functions in ligand binding, tyrosine kinase activation, and growth stimulation. Because the activation of EGFR results in an unfavorable prognosis of patients with colorectal carcinoma, a pilot study was conducted to assess the influence of this polymorphism on colorectal carcinoma patients.

EXPERIMENTAL DESIGN

We retrospectively analyzed the effect of the R497K polymorphism of EGFR on clinicopathologic features in 209 colorectal carcinoma patients, including 100 with stage II/III colorectal carcinoma receiving curative surgery and the other 109 with metastatic diseases.

RESULTS

An excellent correlation in codon 497 statuses examined by patients' WBCs and tumor tissues was found but no significant between-group difference in patients with or without colorectal carcinoma (P = 0.97). A marked decrease on EGFR phosphorylation (P < 0.01) and c-Myc activation (P = 0.02) was observed in patients with R497K polymorphism, which is associated with decreased invasion (P = 0.01), lower nodal involvement (P = 0.02), reduced subsequent metastasis (P < 0.01), and longer disease-free (P < 0.01) as well as overall (P < 0.01) survival in stage II/III colorectal carcinoma patients who had received curative surgery. For patients with metastatic colorectal carcinoma, this polymorphism was associated with a higher response to 5-fluorouracil/oxaliplatin treatment (P = 0.02) and a longer survival (P < 0.01). By multivariate analysis, this polymorphism was also identified as an independent prognostic factor (P = 0.03).

CONCLUSIONS

These data suggest that the R497K polymorphism of the EGFR, by reducing its activation and a consequential down-regulation of its target genes, could be a key determinant for reduced tumor recurrence of stage II/III colorectal carcinoma patients receiving curative surgery and a longer survival of patients with stage II/III as well as metastatic colorectal carcinoma.

Tumour markers in colorectal cancer: European Group on Tumour Markers (EGTM) guidelines for clinical use

The aim of this article is to present updated guidelines for the use of serum, tissue and faecal markers in colorectal cancer (CRC). Lack of specificity and sensitivity preclude the use of all existing serum markers for the early detection of CRC. For patients with stage II or stage III CRC who may be candidates for either liver resection or systemic treatment should recurrence develop, CEA should be measured every 2-3 months for at least 3 years after diagnosis. Insufficient evidence exists to recommend routine use of tissue factors such as thymidylate synthase, microsatellite instability (MSI), p53, K-ras and deleted in colon cancer (DCC) for either determining prognosis or predicting response to therapy in patients with CRC. Microsatellite instability, however, may be used as a pre-screen for patients with suspected hereditary non-polyposis colorectal cancer. Faecal occult blood testing but not faecal DNA markers may be used to screen asymptomatic subjects 50 years or older for early CRC.

Expanded Treatment Options in the Adjuvant Therapy of Colon Cancer: Implications for Oncology Nurses

PURPOSE/OBJECTIVES

To review the role of adjuvant therapy in the treatment of patients with colon cancer.

DATA SOURCES

Published articles, Internet sources, and books.

DATA SYNTHESIS

Colon cancer is a very common cancer in men and women. Chemotherapy, consisting primarily of 5-fluorouracil, has been used to treat colon cancer since the 1950s, but additional effective agents against metastatic disease now are available. The options for adjuvant chemotherapy have increased dramatically. Ongoing studies are evaluating the role of biologics in adjuvant therapy of colon cancer.

CONCLUSIONS

Use of oxaliplatin in the adjuvant setting has further defined exciting new therapy options for patients with colon cancer.

IMPLICATIONS FOR NURSING

Oncology nurses caring for patients with colon cancer should be aware of new changes in therapy options. Although the addition of new therapies increases the tools in the drug arsenal for the common disease, management of toxicities of therapy is crucial as well. This article reviews changes in therapy options and toxicity management, including discussion of key issues for oncology nurses in the care of patients with colon cancer.

The histone deacetylase inhibitor PXD101 synergises with 5-fluorouracil to inhibit colon cancer cell growth in vitro and in vivo

PURPOSE

Histone deacetylase inhibitors (HDACi) inhibit the growth of cancer cells, and combinations of HDACi with established chemotherapeutics can lead to synergistic effects. We have investigated effects of PXD101 (HDACi in phase II clinical trials) in combination with 5-fluorouracil, on tumour cell proliferation and apoptosis both in vitro and in vivo.

EXPERIMENTAL DESIGN

HCT116 cells were studied using proliferation and clonogenic assays. Synergistic inhibition of proliferation and clonogenicity was determined by incubation with PXD101 and 5-fluorouracil, and analysis using CalcuSyn software. The effect of combining PXD101 and 5-fluorouracil on apoptosis was examined in vitro using PARP-cleavage and TUNEL. Finally, the effectiveness of combining PXD101 and 5-fluorouracil in vivo was tested using both HT-29 and HCT116 xenograft models.

RESULTS

Synergistic inhibition of proliferation and clonogenicity was obtained when HCT116 cells were incubated with PXD101 and 5-fluorouracil. 5-fluorouracil combined with PXD101 also increased DNA fragmentation and PARP cleavage in HCT116 cells. Incubation with PXD101 down regulated thymidylate synthase expression in HCT116 cells. In vivo studies, using mouse HT29 and HCT116 xenograft models, showed improved reductions in tumour volume compared to single compound, when PXD101 and 5-fluorouracil were combined.

CONCLUSIONS

PXD101 and 5-fluorouracil synergistically combine in their anti-tumour effects against colon cancer cells in vitro and show enhanced activity when combined in vivo. Based on the results presented herein, a rationale for the use of PXD101 and 5-fluorouracil in combination in the clinic has been demonstrated.

Which gene is a dominant predictor of response during FOLFOX chemotherapy for the treatment of metastatic colorectal cancer, the MTHFR or XRCC1 gene?

BACKGROUND

Combination chemotherapy using oxaliplatin, 5-fluorouracil and folinic acid (FOLFOX) is known to be effective in the treatment of metastatic colon cancer. Genes regulating the actions of 5-fluorouracil and oxaliplatin have been identified, but precisely which gene is dominant has not yet been determined. The aim of the investigation reported here was to identify which gene polymorphism is a dominant factor in FOLFOX chemotherapy-the methylenetetrahydrofolate reductase (MTHFR) gene for 5-fluorouracil or the X-ray cross-complementing1 (XRCC1) gene for oxaliplatin.

METHODS

Paraffin-embedded tissues from 54 patients with unresectable metastases from colorectal cancer who had undergone chemotherapy with the FOLFOX regimen were analyzed for MTHFR polymorphisms in the MTHFR gene (677C-->T, Ala-->Val mutation) and XRCC1 gene (Arg-->Gln substitution in exon 10). Response rates and survivals were compared by types of polymorphism.

RESULTS

Analyses of the patterns of MTHFR polymorphism revealed that 29.6% of the patients showed no mutation, 51.6% showed heterozygous mutations, and 11.8% showed homozygous mutations. Analyses of the XRCC1 polymorphism revealed that 60.8% of the patients showed no mutation, 31.4% showed heterozygous mutations, and 7.8% showed homozygous mutations. After four cycles of chemotherapy, 3.7% showed a complete response, 57.4% showed a partial response (PD) or stable disease, and 38.9% showed PD. The MTHFR polymorphism was not significant in predicting response and 30-month-survival (P > .1), whereas the XRCC1 polymorphism was a significant prognostic factor for both response (P = .038) and survival (P = .011).

CONCLUSIONS

We found a higher rate of mutations in the MTHFR gene than in the XRCC1 gene in Korean colorectal cancer patients. Response to FOLFOX was better in the patient group with mutations for MTHFR and worse in the patient group with mutations for XRCC1. However, only the XRCC1 polymorphism was a significant prognostic factor for the response to FOLFOX chemotherapy and short-term survival.

Clinical Implications of Our Advancing Knowledge of Colorectal Cancer Genetics: Inherited Syndromes, Prognosis, Prevention, Screening and Therapeutics

Recent genetic advances in our knowledge of colorectal cancer genetics are beginning to pay translational dividends in the management of this common clinical problem. We are now able to accurately screen and counsel individuals at risk of rare inherited cancer syndromes. We have recently introduced two of what are sure to be numerous biologic-based therapies, and have shown that colorectal neoplasia risk can be modestly reduced by various chemopreventative agents. Finally, our advancing knowledge has led to significant inroads into understanding what genetic alterations define prognosis and predict response to specific chemotherapeutic agents, and we are beginning to explore the utility of this knowledge in mass genetic-based clinical screening efforts. Enthusiasm must be tempered, however, by the extraordinary cost that often accompanies relatively modest gains. Finally, although genetic-based therapy often receives the greatest attention, molecular genetics, will likely have the greatest cost-effective impact in primary prevention and early diagnosis.

Prognostic value of Thymidylate Synthase, Epidermal Growth Factor Receptors and Vascular Endothelial Growth Factor in patients with stage III colon cancer

Purpose: We studied the prognostic value of thymidylate synthase (TS), Epidermal Growth Factor Receptors (EGFR) and Vascular Endothelial Growth Factor (VEGF) expression in primary colon cancer (CC). Patients and Methods : Those three markers were immunohistochemically assessed on tumor sections from 100 patients with CC Dukes C. All patients received the same adjuvant chemotherapy with FU/Leukovocin according to Mayo protocol. Considering the clinical course they were classified in two groups: bad in which all patients progressed and good in which neither progressed during the five year follow up period. Results: TS, EGFR and VEGF were an independent prognostic factor for time to progression (TTP) and overall survival (OS). Findings of at least two maximum expressed investigated markers, significantly increases the risk of progression which influences shorter five year survival, and the single maximum expression does not necessarily have to be a bad prognostic sign. Conclusion: Highest expression of TS, EGFR and VEGF carries prognostic significance with respect to TTP and OS for patients with Dukes C colon cancer.

Colorectal cancer surveillance: 2005 update of an American Society of Clinical Oncology practice guideline

PURPOSE

To update the 2000 American Society of Clinical Oncology guideline on colorectal cancer surveillance.

RECOMMENDATIONS

Based on results from three independently reported meta-analyses of randomized controlled trials that compared low-intensity and high-intensity programs of colorectal cancer surveillance, and on recent analyses of data from major clinical trials in colon and rectal cancer, the Panel recommends annual computed tomography (CT) of the chest and abdomen for 3 years after primary therapy for patients who are at higher risk of recurrence and who could be candidates for curative-intent surgery; pelvic CT scan for rectal cancer surveillance, especially for patients with several poor prognostic factors, including those who have not been treated with radiation; colonoscopy at 3 years after operative treatment, and, if results are normal, every 5 years thereafter; flexible proctosigmoidoscopy [corrected] every 6 months for 5 years for rectal cancer patients who have not been treated with pelvic radiation; history and physical examination every 3 to 6 months for the first 3 years, every 6 months during years 4 and 5, and subsequently at the discretion of the physician; and carcinoembryonic antigen every 3 months postoperatively for at least 3 years after diagnosis, if the patient is a candidate for surgery or systemic therapy. Chest x-rays, CBCs, and liver function tests are not recommended, and molecular or cellular markers should not influence the surveillance strategy based on available evidence.