The changing face of chemotherapy in colorectal cancer

HMGB1-mediated autophagy modulates sensitivity of colorectal cancer cells to oxaliplatin via MEK/ERK signaling pathway

In the present study, we examined the mechanisms of oxaliplatin-induced drug resistance in human colorectal cancer cell lines HT29 and HCT116. Our results demonstrate a significant autophagy expression in CRC cells after an oxaliplatin treatment. Administration of oxaliplatin to human CRC cells significantly enhanced the expression of HMGB1, which regulated the autophagy response and negatively regulate the cell apoptosis. Moreover, a decreased oxaliplatin -induced autophagy response and an increased apoptosis level were detected in stable CRC cells harboring HMGB1 shRNA. Then we noted that HMGB1 significantly induced extracellular signal-regulated kinase (ERK)/Extracellular signal-regulated kinase kinase (MEK) phosphorylation. Taken together, these data suggest that HMGB1-mediated autophagy modulates sensitivity of colorectal cancer cells to oxaliplatin via MEK/ERK signaling pathway.

Stichoposide C induces apoptosis through the generation of ceramide in leukemia and colorectal cancer cells and shows in vivo antitumor activity

PURPOSE

Marine triterpene glycosides that are physiologically active natural compounds isolated from sea cucumbers (holothurians) and sponges have antifungal, cytotoxic, and antitumor activities, whose specific molecular mechanisms remain to be elucidated. In this study, we examined if and through which mechanisms stichoposide C (STC) from Thelenota anax (family Stichopodidae) induces apoptosis in leukemia and colorectal cancer cells.

EXPERIMENTAL DESIGN

We examined STC-induced apoptosis in human leukemia and colorectal cancer cells in the context of mitochondrial injury and signaling pathway disturbances, and investigated the antitumor effect of STC in mouse CT-26 subcutaneous tumor and HL-60 leukemia xenograft models.

RESULTS

We found that STC induces apoptosis in these cells in a dose-dependent manner and leads to the activation of Fas and caspase-8, cleavage of Bid, mitochondrial damage, and activation of caspase-3. STC activates acid sphingomyelinase (SMase) and neutral SMase, which resulted in the generation of ceramide. Specific inhibition of acid SMase or neutral SMase and siRNA knockdown experiments partially blocked STC-induced apoptosis. Moreover, STC markedly reduced tumor growth of HL-60 xenograft and CT-26 subcutaneous tumors and increased ceramide generation in vivo.

CONCLUSIONS

Ceramide generation by STC, through activation of acid and neutral SMase, may in part contribute to STC-induced apoptosis and antitumor activity. Thus, STC may have therapeutic relevance for human leukemia and colorectal cancer.

The role of peroxisome proliferator-activated receptors in colorectal cancer

Colorectal cancer is one of the most common cancers in the world. Dietary fat intake is a major risk factor for colorectal cancer. Some nuclear hormone receptors play an important role in regulating nutrient metabolism and energy homeostasis. Among these receptors, special attention has been focused on the role of peroxisome proliferator-activated receptors (PPARs) in colorectal cancer, because PPARs are involved in regulation of lipid and carbohydrate metabolism. PPARs are ligand-activated intracellular transcription factors. The PPAR subfamily consists of three subtypes encoded by distinct genes named PPARα, PPARβ/δ, and PPARγ. PPARγ is the most extensively studied subtype of PPARs. Even though many investigators have studied the expression and clinical implications of PPARs in colorectal cancer, there are still many controversies about the role of PPARs in colorectal cancer. In this paper, the recent progresses in understanding the role of PPARs in colorectal cancer are summarized.

Effect of betulinic acid on anticancer drug-resistant colon cancer cells

Primary or acquired resistance of tumours to established chemotherapeutic regimens is a major concern in oncology. Attempts to improve the survival of cancer patients largely depend on strategies to prevent tumour cell resistance. 5-Fluorouracil (5-FU)-based chemotherapy with a combination of other drugs such as irinotecan (IRT) and oxaliplatin (OXT) has been reported to be effective, even though an optimal regimen has yet to be defined due to the relatively high toxicity of the procedure. The aim of this study was to examine the effect of betulinic acid (BetA) as a chemosensitizer for anticancer drug treatment in chemoresistant colon cancer cell lines. A chemoresistant cell line to 5-fluorouracil (SNU-C5/5FU-R), irinotecan (SNU-C5/IRT-R) and oxaliplatin (SNU-C5/OXT-R) treatment were derived from the wild-type colon adenocarcinoma cell line (SNU-C5/WT). The effect of BetA or a combination of anticancer drugs and BetA on the multidrug resistance-related genes, caspases, Bcl-2, Bad and cell death in the SNU-C5/WT and SNU-C5/R cell lines was analysed. BetA alone was an effective chemotherapeutic drug for the SNU-C5/WT, SNU-C5/5FU-R and SNU-C5/OXT-R cells. The combination of BetA with IRT or OXT was effective against SNU-C5/5FU-R cells, and the combination of BetA with 5-fluorouracil, IRT or OXT was effective against SNU-C5/OXT-R cells. BetA induced cancer cell death by apoptosis through the mitochondrial pathway. These findings indicate that the use of BetA as a chemosensitizer may be a new strategy to enhance the efficacy of chemotherapy. However, further studies will be needed for confirmation.

Topoisomerase I protein expression in primary colorectal cancer and recurrences after 5-FU-based adjuvant chemotherapy

PURPOSE

Our aim was to investigate whether chemotherapy with 5-FU induces an alteration in the levels of topoisomerase I (topo I) in colorectal neoplastic tissues

METHODS

Twenty-five colorectal cancer patients were included in our study; these had undergone surgical resection of the primary tumor, received post-operatively 5-FU-based adjuvant chemotherapy and then suffered from recurrences. In a standard three-step immunohistochemical procedure, a monoclonal antibody to topo I was applied in both specimens from each patient (one from the primary location and a second one from the recurrence). Statistical analysis was subsequently performed.

RESULTS

Malignant cells from the recurrences displayed a statistical significant increase, concerning the levels of topoisomerase I, by comparison with the primary tumors (P=0.01). The increase in topo I levels did not demonstrate significant correlations with Duke's stage (Fisher's Exact Test P value=0.496), differentiation grade (P value=0.661), localization (P value=0.072), patient sex (P value=0.434), nor with relapse free interval (P value=0.493). There was a statistically significant relationship between the age of patients and increase in topo I levels (P=0.011).

CONCLUSIONS

Topo I expression may be part of the malignant cells' phenotype in recurrent colorectal carcinomas, suggesting a potential role for Topo I in the acquisition of a metastatic phenotype. The increase of topo I immunohistochemical status is likely to be attributed to 5-FU and given the fact that high levels of topo I correlate with sensitivity to camptothecin, advanced colorectal cancer patients seem to benefit from topo I targeted anticancer drug therapy.

Molecular determinants of irinotecan efficacy

Molecular markers predicting the efficacy of CPT-11 based chemotherapies in patients with colorectal cancer (CRC) are unknown. Therefore, we investigated whether mRNA levels of drug targets (Topoisomerase I, TS), enzymes involved in 5-FU metabolism (DPD), in angiogenesis (EGFR, IL-8, VEGF) and in DNA-repair/drug detoxification (ERCC1, GST-P1) are associated with the clinical outcome of patients with CRC treated with first-line CPT-11 based chemotherapy. Thirty three patients with metastatic CRC were included in the study. Intratumoral gene expression levels were assessed from paraffin-embedded tissue samples, using laser capture microdissection and quantitative Real-Time PCR. Complete response was observed in 1 patient, partial response in 12 patients, stable disease in 13 patients and progressive disease in 6 patients. Response was inevaluable for 1 patient. Patients with complete response or partial response were classified as responders, while patients with stable disease or progressive disease were classified as nonresponders. High intratumoral mRNA levels of EGFR, ERCC1 and GSPT-P1 were each significantly associated with response to CPT-11 based chemotherapy. Recursive partitioning analysis showed that mRNA levels of EGFR and ERCC1 are primarily responsible for delineating responders from nonresponders. Also, the combination of high intratumoral gene expression levels of both EGFR and ERCC1 was significantly associated with progression-free survival. The mRNA levels of EGFR had a significant correlation with expression levels of ERCC1, GST-P1 and VEGF. This small retrospective study suggests that gene expression levels of EGFR, ERCC1 and GST-P1 may be useful in predicting the clinical outcome of patients with metastatic CRC treated with first-line CPT-11 based chemotherapy.

Crypt dynamics and colorectal cancer: advances in mathematical modelling

Mathematical modelling forms a key component of systems biology, offering insights that complement and stimulate experimental studies. In this review, we illustrate the role of theoretical models in elucidating the mechanisms involved in normal intestinal crypt dynamics and colorectal cancer. We discuss a range of modelling approaches, including models that describe cell proliferation, migration, differentiation, crypt fission, genetic instability, APC inactivation and tumour heterogeneity. We focus on the model assumptions, limitations and applications, rather than on the technical details. We also present a new stochastic model for stem-cell dynamics, which predicts that, on average, APC inactivation occurs more quickly in the stem-cell pool in the absence of symmetric cell division. This suggests that natural niche succession may protect stem cells against malignant transformation in the gut. Finally, we explain how we aim to gain further understanding of the crypt system and of colorectal carcinogenesis with the aid of multiscale models that cover all levels of organization from the molecular to the whole organ.

Pioglitazone, a synthetic ligand for PPARγ, induces apoptosis in RB-deficient human colorectal cancer cells

No published data are available about the expression of peroxisome proliferator-activated receptor gamma (PPARgamma) and the role of PPARgamma in retinoblastoma protein (RB)-deficient human colorectal cancer (CRC) cells (SNU-C4 and SNU-C2A). Our aim was to investigate whether PPARgamma is expressed in SNU-C4 and SNU-C2A cells and to elucidate possible molecular mechanisms underlying the effect of pioglitazone, a synthetic ligand for PPARgamma, on cell growth in these cell lines. RT-PCR and Western blot analysis showed that both human CRC cell lines expressed PPARgamma mRNA and protein. Pioglitazone inhibited the cell growth of both cell lines through G2/M phase block and apoptosis. In addition, pioglitazone caused a down-regulation of the X chromosome-linked inhibitor of apoptosis (XIAP), Bcl-2, and cyclooxygenase-2 (COX-2) under conditions leading to PPARgamma down-regulation. These results suggest that pioglitazone may have therapeutic relevance or significance in the treatment of human CRC, and the down-regulation of XIAP, Bcl-2, and COX-2 may contribute to pioglitazone-induced apoptosis in these and other RB-deficient cell lines and tumors.

Topoisomerase-I, thymidylate synthase primary tumour expression and clinical efficacy of 5-FU/CPT-11 chemotherapy in advanced colorectal cancer patients

While several studies have reported that thymidylate synthase (TS) tumour expression can be a reliable predictive marker of clinical response to 5-Fluorouracil (5-FU) for advanced colorectal cancer patients, only a few studies that searched for predictive factors of irinotecan (CPT-11) clinical response are available. The aim of the present study has been to verify the predictive value of immunohistochemical topoisomerase-I (Topo-I) and TS primary tumour expression in a consecutive series of 62 advanced colorectal cancer patients that received a first line 5-FU/CPT-11 chemotherapy. TS and Topo-I immunostaining was observed in 76% and 43% of tumours, respectively, resulting in a significant relationship within each tumour (r=0.365, p<0.004). Patients with different TS tumour expression showed a similar percentage of Objective Clinical Response, OR (40% vs. 28% of OR in low and high TS-expressing tumours, respectively, p=ns); also, patients with different Topo-I tumour expression did not show a different probability of OR (39% vs. 29% of OR in high and low Topo-I expressing tumours, respectively; p=ns). The tumour expression of these 2 biomarkers also did not impact on time to progression and overall survival of patients. Furthermore, the combined analysis of TS and Topo-I tumour status did not permit to individualize subgroups of patients with different probability of OR. With multivariate analysis, only patient Performance Status significantly impacted on OS (Hazard ratio 4.87; p=0.02) of these patients. We can conclude that high TS tumour expression seems not to preclude a clinical activity for 5-FU/CPT-11 polichemotherapy in advanced colorectal cancer patients; furthermore, clinical response and prognosis of colorectal cancer patients treated with 5-FU/CPT-11 regimen do not differ in tumours with different TS or Topo-I expression.

Oxaliplatin with biweekly, low dose leucovorin and bolus and continuous infusion 5-fluorouracil (Modified FOLFOX 4) as first-line therapy for patients with metastatic colorectal cancer

PURPOSE

To determine the activity and toxicities of low dose leucovorin (LV) plus fluorouracil (5-FU) regimen, combined with oxaliplatin every two weeks (modified FOLFOX 4), as a first-line therapy for patients with metastatic colorectal cancer.

MATERIALS AND METHODS

Between March 2001 and August 2003, fifty-five patients were enrolled in this study. Patients were treated with oxaliplatin 85 mg/m(2) as a 2-hour infusion at days 1 plus LV 20 mg/m(2) over 10 minutes, followed by 5-FU bolusa 400 mg/m(2) bolus and 22 hour continuous infusion of 600 mg/m(2) 5-FU at day 1 approximately 2. This treatment was repeated in 2 week intervals.

RESULTS

The objective response rate was 40% on an intent-to-treatment analysis. Three patients (6%) demonstrated a complete response and nineteen patients (38%) showed a partial response. Sixteen patients (32%) showed a stable disease and eleven patients (22%) progressed during the course of the treatment. The median time to progression and overall survival time were as 6.6 months (95% CI: 4.98 approximately 8.02 months) and the median overall survival time was 17.0 months (95% CI: 9.15 approximately 24.85 months) from the start of the chemotherapy, respectively. A total of 275 cycles were analyzed for toxicity. Major hematologic toxicities included grade 1 approximately 2 anemia (23.5%), neutropenia (25.3%) and thrombocytopenia (10.6%). There were only 2 cycles of neutropenic fever. The most common non-hematologic toxicities were grade 1 approximately 2 nausea/vomiting (10.9%), diarrhea (9.1%) and grade 1 neuropathy (18.0%). There was no treatment related death.

CONCLUSION

The modified folfox 4 regimen is safe and effective regimen as a first-line therapy in advanced colorectal cancer patients.

A dose-escalating study of oral eniluracil/5-fluorouracil plus oxaliplatin in patients with advanced gastrointestinal malignancies

BACKGROUND

Oral eniluracil/5-fluorouracil (5-FU) was shown in early clinical studies to have promising activity against gastrointestinal malignancies. Oxaliplatin in combination with 5-FU also has activity against these tumour types. The primary objective of this study was to determine a tolerable dose for oral eniluracil/5-FU in combination with oxaliplatin.

PATIENTS AND METHODS

Twenty-three patients with advanced gastrointestinal malignancies were recruited into this open-label study. Patients received a fixed dose of oxaliplatin (130 mg/m(2) on the first day of a 21-day cycle), and the dose intensity of oral eniluracil/5-FU was gradually increased by escalating the number of days of treatment per course.

RESULTS

The maximum tolerated dose intensity was eniluracil/5-FU 10.0/1.0 mg/m(2) twice daily for 16 days in combination with oxaliplatin 130 mg/m(2) on the first day of a 21-day cycle. Dose-limiting toxicities included vomiting and diarrhoea. The objective tumour response rate was 26% with a median duration of response of 15.3 weeks (95% confidence interval 8.5-22.1). Twenty-two patients (96%) experienced neurotoxicity (sensory neuropathy or cold-related dysaesthesia), although only two events were severe (grade 3).

CONCLUSIONS

The recommended dose for future study in patients with advanced gastrointestinal cancer is 10.0/1.0 mg/m(2) oral eniluracil/5-FU twice daily for 14 days in combination with oxaliplatin 130 mg/m(2) on the first day of each treatment cycle.

Combination of 5-fluorouracil and irinotecan on modulation of thymidylate synthase and topoisomerase I expression and cell cycle regulation in human colon cancer LoVo cells: clinical relevance

This study was designed to explore the possible interaction of 5-fluorouracil (5-FU) and 7-ethyl-10-hydroxycamptothecin (SN-38) in vitro. Human colon cancer LoVo cells were treated in both a dose- and time-dependent manner using clinically relevant concentrations of and exposure to 5-FU and/or SN-38. The expression of thymidylate synthase (TS), topoisomerase I, and cell cycle kinetics were evaluated by Western blot analysis and flow cytometry, respectively. Cytotoxicity was evaluated by MTT (3-[4,5-dimethylthiazol-2yl]-2,5-diphenyl tetrazolium bromide) assay. The cytotoxic effects of combination treatment were determined by median effect analysis. Topoisomerase I expression was downregulated following 12 hours of exposure to treatment, and topoisomerase I expression recovered 8 hours after SN-38 was removed. The TS expression was decreased following 24 hours of 5-FU and it remained at reduced levels for > 24 hours after removal of 5-FU. SN-38 induced an arrest at S/G2/M phase, reaching its maximum effect at 12 hours. This cell cycle arrest was reversed 24 hours after SN-38 was removed. 5-FU induced an arrest at the S phase, and maximum arrest occurred at 12 hours and lasted for > 48 hours. After 12 hours of sequential SN-38, LoVo cells were arrested in S phase, thereby potentiating the effect of 5-FU. Cytotoxicity studies confirmed the synergistic interaction between 5-FU and irinotecan. These findings suggest that the proper sequencing of 5-FU/irinotecan depends on regulation of topoisomerase I, and cell cycle kinetics

Drug specific resistance to oxaliplatin is associated with apoptosis defect in a cellular model of colon carcinoma

To investigate acquired resistance to oxaliplatin, we selected two resistant clones from the HCT116 cell line. We found that the resistant phenotype was associated with resistance to oxaliplatin-induced apoptosis as demonstrated by FACS analysis and by Western blotting of caspase 3 activation. In addition, the resistant phenotype showed a concomitant resistance to lonidamine and arsenic trioxide which are inducers of mitochondrial apoptosis. Furthermore, a complete loss of Bax expression due to a frameshift mutation was observed in the most resistant clone. Taken together, these findings suggest that altered mitochondrial-mediated apoptosis could play a role in oxaliplatin resistance.

Biweekly chemotherapy with oxaliplatin, irinotecan, infusional Fluorouracil, and leucovorin: a pilot study in patients with metastatic colorectal cancer

PURPOSE

To determine the feasibility, recommended doses, plasma pharmacokinetics, and antitumor activity of a biweekly chemotherapy regimen with oxaliplatin (L-OHP), irinotecan (CPT-11), infusional fluorouracil (5-FU), and leucovorin (LV) in metastatic colorectal cancer patients.

PATIENTS AND METHODS

Patients received CPT-11 followed by L-OHP and LV 200 mg/m(2) and followed by 5-FU 3,800 mg/m(2) as a 48-hour infusion, repeated every 2 weeks. In the first part of the study, an escalation of CPT-11 dose and/or a decrease of the L-OHP dose were planned. Once the recommended doses of CPT-11 and L-OHP were determined, all subsequent patients were treated at the recommended doses.

RESULTS

Forty-two patients entered the study. CPT-11 175 mg/m(2) and L-OHP 100 mg/m(2) in combination with LV 200 mg/m(2) and 5-FU 3,800 mg/m(2) could be administered with acceptable toxicities; 39 patients were treated at these dose levels. The pharmacokinetics parameters of the agents used and their metabolites did not seem to be influenced by the concomitant use of the other drugs. The most relevant toxicities were diarrhea and neutropenia, with 14% of patients experiencing one episode of febrile neutropenia. In five patients (11.9%) a complete and in 25 (59.5%) a partial response was demonstrated, for an objective response rate of 71.4% (95% confidence interval, 47% to 83%). In 11 patients (26%), a surgical resection of residual disease could be performed. Median progression-free and overall survival times were 10.4 and 26.5 months, respectively.

CONCLUSION

This biweekly regimen is feasible and has acceptable and manageable toxicities and no apparent relevant pharmacokinetics interactions. This combination is associated with a promising antitumor activity, time to progression, and survival. A phase III randomized trial in Italy planned by the Gruppo Oncologico Nord Ovest has just started.

Irinotecan and raltitrexed: an active combination in advanced colorectal cancer

BACKGROUND

Irinotecan and raltitrexed are active agents in metastatic colorectal cancer. Preclinical findings suggest a remarkable synergistic activity between the two drugs and the feasibility of this association has been shown in a recent phase I study. The aim of our phase II trial was to assess the efficacy and tolerability of the combination of irinotecan and raltitrexed in patients with metastatic colorectal cancer untreated with chemotherapy.

PATIENTS AND METHODS

From June 1998 to February 2000, 46 patients were enrolled. Patients received irinotecan 350 mg/m(2) on day 1 and raltitrexed 2.6 mg/m(2) on day 2, every 3 weeks, for up to nine courses. Tumour assessment was performed every three cycles.

RESULTS

A total of 223 cycles of chemotherapy, with a median number of six (range 1-9) courses per patient, was administered. According to intention-to-treat analysis, the overall response rate was 46% (95% confidence interval 31% to 61%). The median duration of response was 21 weeks (range 11-> or =101), the median time to progression 27 weeks (range 1-> or =116), and the median overall survival 57 weeks (range 1-> or =130). The main toxicities were diarrhoea, with National Cancer Institute common toxicity criteria grade 3/4 in 26% of patients, grade 3/4 neutropenia in 20%, grade 3 nausea-vomiting in 13%, grade 3 asthenia in 11% and grade 3/4 transaminase elevation in 4%.

CONCLUSIONS

Results achieved with irinotecan and raltitrexed show that this regimen is active, despite 'not-negligible' toxicity, and may represent a useful regimen for specific subgroups of colorectal cancer patients.