Apoptosis and its correlation with proliferative activity in rectal cancer

Clinical-pathological characteristics and short-term follow-up associated with proliferation, apoptosis and angiogenesis in a prospective cohort of patients with colorectal tumours

We investigate the clinical and pathological features related to variations in colorectal tumour apoptosis, proliferation and angiogenesis and the influence of the latter in short-term mortality (2 years); 551 tumour samples from a prospective cohort of patients with colorectal cancer were examined and tumour biology markers were determined as follows: percentage of apoptotic cells, by the terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling technique; Ki-67 antigen, as a cell proliferation marker and density of microvessels (as a marker of angiogenesis). An increase in the percentage of cellular apoptosis is significantly related to the presence of poorly differentiated tumours, with vascular invasion (p < 0.001). The CD105 angiogenesis marker is not related to any clinical-pathological parameter except that of higher frequency in older patients (p = 0.03). Ki-67 is more frequently expressed in tumours with less nervous invasion (p = 0.05). Neither apoptosis nor angiogenesis present any significant association with short-term survival. The only marker clearly related to 2-year survival is Ki-67, which is shown to be a good prognostic factor in the multivariate analysis (hazard ratio = 0.49; 95% confidence interval = 0.27-0.90). Therefore, in a prospective cohort of colorectal cancer patients, only Ki-67 is a marker of good prognosis in short-term follow-up.

DNA methylation of apoptosis genes in rectal cancer predicts patient survival and tumor recurrence

Deregulation of the apoptotic pathway, one of the hallmarks of tumor growth and -progression, has been shown to have prognostic value for tumor recurrence in rectal cancer. In order to develop clinically relevant biomarkers, we studied the methylation status of promoter regions of key apoptosis genes in rectal cancer patients, using methylation-sensitive restriction enzymes. DNA was extracted from fresh-frozen tumor tissues of 49 stage I-III rectal cancer patients and 10 normal rectal tissues. The results of this pilot study were validated in 88 stage III tumor tissues and 18 normal rectal tissues. We found that methylation of the intrinsic apoptotic pathway genes Apaf1, Bcl2 and p53 correlated with the apoptotic status (M30) of the tumor. Combined survival analyses of these three genes, based on the number of genes showing high methylation (all low, 1 high, 2 high or all high), showed shorter patient survival and recurrence-free periods with an increasing number of methylated markers. Multivariate analyses showed significant differences for overall survival (p = 0.01; HR = 0.28 (0.09-0.83)), cancer-specific survival (p = 0.004; HR = 0.13 (0.03-0.67)) and distant recurrence-free survival (p = 0.001; HR = 0.22(0.05-0.94)). The shortest survival was observed for patients showing low methylation of all markers, which-as was expected-correlated with high apoptosis (M30), but also with high proliferation (Ki-67). The study of epigenetic regulation of apoptosis genes provides more insight in the tumorigenic process in rectal cancer and might be helpful in further refining treatment regimens for individual patients.

The role and prognostic value of apoptosis in colorectal carcinoma

Background

Alterations to apoptosis are a common occurrence in human tumours. The aim of our study was to determine the influence of apoptotic variations on the carcinogenesis and prognosis of colorectal carcinomas (CRCs).

Methods

A TUNEL assay was performed on archival material from 103 colorectal carcinomas, 26 adenomas and 20 samples of normal epithelia.

Results

The number of apoptotic cells was higher in CRCs (1.09 ± 0.13) than in adenomas (0.38 ± 0.23, p = 0.059) and normal epithelium (0.06 ± 0.04, p = 0.001). In addition, the apoptotic index (AI) was greater in metastatic disease (stage IV) than in other stages (p = 0.017). No relationship was found between apoptotic rates and age, gender or tumour grade. However, patients with tumours that showed higher AI values had a significantly lower disease-free survival (DFS) and overall survival (OS) than those with tumours that had lower AIs (p = 0.020 and p = 0.027). In a multivariate Cox proportional hazards model, AI remained a significant independent predictor of survival.

Conclusions

We conclude that disregulated apoptosis is an important event during CRC development and progression. Higher AIs are associated with more aggressive tumours and a poorer prognosis for patients with CRC.

Biological predictors of survival in stage II colorectal cancer

The routine use of postoperative adjuvant chemotherapy in patients with stage II colorectal cancer is not recommended. However, the incidence of tumor recurrence or distant metastasis in these patients is reported to be 25–35%. The identification of high-risk patients with stage II colorectal cancer remains difficult. Therefore, the aim of this study was to determine the risk factors that may help identify stage II colorectal cancer patients with unfavorable prognosis. Paraffin-embedded tissue samples from 109 patients with stage II colorectal cancer following curative operation were analyzed. Thirteen clinicopathological variables and 5 biological markers were assessed using immunohistochemistry, including p53 (tumor suppressor gene), CD10 (tumor invasion marker), CD34 (angiogenic marker), Ki-67 (cell proliferation index) and CAM 5.2 (marker of lymph node micrometastasis) and investigated for associations with disease-specific survival. Univariate analysis revealed bowel obstruction, lymph node micrometastasis and lymphatic invasion (P<0.01) to be highly significant factors for determining the 5-year disease-specific survival. By contrast, the multivariate analysis revealed lymph node micrometastasis and lymphatic invasion to be independent prognostic factors. Stage II colorectal cancer patients with lymph node micrometastasis and lymphatic invasion may therefore be suitable candidates for adjuvant chemotherapy to improve prognosis.

Human equilibrative nucleoside transporter 1 and carcinoma of the ampulla of Vater: expression differences in tumour histotypes

The human equilibrative nucleoside transporter 1 (hENT1) is the major means by which gemcitabine enters human cells; recent evidence exists that hENT1 is expressed in carcinoma of the ampulla of Vater and that it should be considered as a molecular prognostic marker for patients with resected ampullary cancer. Aim of the present study is to evaluate the variations of hENT1 expression in ampullary carcinomas and to correlate such variations with histological subtypes and clinicopathological parameters. Forty-one ampullary carcinomas were histologically classified into intestinal, pancreaticobiliary and unusual types. hENT1 and Ki67 expression were evaluated by immunohistochemistry, and apoptotic cells were identified by the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labelling (TUNEL) method. hENT1 overexpression was detected in 63.4% ampullary carcinomas. A significant difference in terms of hENT1 and Ki67 expression was found between intestinal vs. pancreaticobiliary types (P=0.03 and P=0.009 respectively). Moreover, a significant statistical positive correlation was found between apoptotic and proliferative Index (P=0.036), while no significant correlation was found between hENT1 and apoptosis. Our results on hENT1 expression suggest that classification of ampullary carcinoma by morphological subtypes may represent an additional tool in prospective clinical trials aimed at examining treatment efficacy; in addition, data obtained from Ki67 and TUNEL suggest a key role of hENT1 in tumour growth of ampullary carcinoma.

Expression of beta-F1-ATPase and mitochondrial transcription factor A and the change in mitochondrial DNA content in colorectal cancer: clinical data analysis and evidence from an in vitro study

PURPOSE

Mitochondria play an important role in regulating apoptosis and thus may be involved in tumor progression. This study was conducted to elucidate the role of mitochondrial dysfunction in colorectal cancer (CRC).

METHODS

Mitochondrial DNA (mtDNA) content was analyzed with real-time polymerase chain reaction in 153 CRC patients who had received surgery at the Taipei Veterans General Hospital from January 1999 to December 2000. The expression of mitochondrial transcription factor A (TFAM) and beta-F1-ATPase were analyzed using immunohistochemistry. HCT116 cells were cultured in 1% O(2) for at least 20 passages. Mitochondrial biogenesis, ATP production, and the apoptotic response to 5-fluorouracil were analyzed in the derived cells.

RESULTS

Disease stage was associated with changes in mtDNA content (p < 0.001), expression of TFAM (p = 0.004), and/or beta-F1-ATPase (p < 0.001). CRCs with low expression of TFAM or beta-F1-ATPase had a lower mtDNA content. In the multivariate analysis, disease stage was the most significant prognostic factor [95% confidence interval (CI), 2.82-6.23], followed by beta-F1-ATPase [95% CI, 1.10-4.10]. In patients receiving 5-FU based chemotherapy, the 5-year disease-free survival rate was only 27% in CRC patients with a low beta-F1-ATPase tumor and was significantly lower than that in those with a high beta-F1-ATPase tumor (60%; p = 0.042). In the hypoxia-treated cells, mitochondrial mass increased, mtDNA content decreased, sensitivity to 5-fluorouracil decreased, and beta-F1-ATPase expression decreased.

CONCLUSION

Mitochondrial dysfunction may be associated with poor outcomes in CRC patients.

Phase II study of weekly intravenous oxaliplatin combined with oral daily capecitabine and radiotherapy with biologic correlates in neoadjuvant treatment of rectal adenocarcinoma

PURPOSE

To evaluate the efficacy of a combination of capecitabine, oxaliplatin, and radiotherapy (RT) in the neoadjuvant treatment of Stage II and III rectal cancers.

METHODS

Capecitabine was given at 725 mg/m(2) orally twice daily Monday through Friday concurrently with RT. Oxaliplatin was given intravenously at 50 mg/m(2) once weekly five times starting the first day of RT. The radiation dose was 50.4 Gy in 28 fractions (1.8 Gy/fraction), five fractions weekly. Endorectal tumor biopsies were obtained before treatment and on the third day of treatment to explore the effects of treatment on thymidine phosphorylase, thymidylate synthase, excision repair cross-complementing rodent repair deficiency complementation group 1 (ERCC1), and apoptosis.

RESULTS

A total of 25 patients were enrolled in this study; 6 patients (24%) had a complete pathologic response. T-downstaging occurred in 52% of patients, and N-downstaging occurred in 53%. Grade 3 diarrhea was the most common Grade 3-4 toxicity, occurring in 20% of patients. Only 2 patients experienced disease recurrence, with a median of 20 months of follow-up. Thymidylate synthase, thymidine phosphorylase, ERCC1, and apoptosis did not vary significantly between the pretreatment and Day 3 tumor biopsies, nor did they predict for T-downstaging or a complete pathologic response.

CONCLUSION

Capecitabine at 725 mg/m(2) orally twice daily, oxaliplatin 50 mg/m(2)/wk, and RT at 50.4 Gy is an effective neoadjuvant combination for Stage II and III rectal cancer and results in a greater rate of complete pathologic responses than historically shown in fluoropyrimidine plus RT controls.

Cytokeratin Markers Come of Age

Cytokeratins have been extensively used as serum tumour markers for monitoring of disease progression in cancer patients. The source of cytokeratins in the circulation as well as the mechanisms of release from cells have long been unclear. Recent evidence suggests that cytokeratins present in the circulation of cancer patients are released from apoptotic or necrotic tumour cells. CK18 is cleaved by caspases during apoptosis and a monoclonal antibody (M30) specific to caspase-cleaved forms is available. The molecular form of CK18 released from cells (caspase-cleaved or not) can conveniently be determined by immunoassays (M30-Apoptosense and M65 ELISA assays; Peviva AB, Bromma, Sweden) to determine cell death mode--apoptosis or necrosis. Recent studies where these assays were used to evaluate the response to cytotoxic anticancer drugs using cancer patient serum have been encouraging. CK18 is attracting considerable interest as a response biomarker during clinical trials of anticancer drugs. Properties such as excellent antigen stability and the epithelial specificity of cytokeratins contribute to make this biomarker attractive.

Scoring of p53, VEGF, Bcl-2 and APAF-1 immunohistochemistry and interobserver reliability in colorectal cancer

Molecular tumor markers are often studied in colorectal cancer using immunohistochemistry to determine their prognostic or predictive value. Protein expression is typically assigned a 'positive' score based on a predetermined cutoff. A semiquantitative scoring method that evaluates the percentage of positive tumor cells (0-100%) may provide a better understanding of the prognostic or predictive significance of these markers. The aim of this study was to assess and compare the interobserver agreement of immunohistochemistry scores using a percentage scoring method and three categorical scoring systems. Immunohistochemistry for p53, Bcl-2, vascular endothelial growth factor (VEGF) and apoptotic protease activating factor-1 (APAF-1) was performed on 87 tumor biopsies from patients with rectal carcinoma and scored independently by four pathologists as the percentage of positive tumor cells. Interobserver agreement was assessed by the intraclass correlation coefficient. The intraclass correlation coefficients for p53 and VEGF (>0.6) indicate substantial agreement between observers. The distribution of Bcl-2 and APAF-1 scores in addition to weaker interobserver agreement by percentage scoring suggest that this approach may not be appropriate for these proteins. In conclusion, p53 and VEGF protein expression assessed by immunohistochemistry in colorectal cancer and scored as a percentage of positive tumor cells may be a viable alternative scoring method.

A Phase I study of weekly intravenous oxaliplatin in combination with oral daily capecitabine and radiation therapy in the neoadjuvant treatment of rectal adenocarcinoma

PURPOSE

We conducted a Phase I study to determine the maximum tolerated dose (MTD) of neoadjuvant capecitabine, oxaliplatin, and radiation therapy (RT) in Stage II to III rectal adenocarcinoma.

METHODS AND MATERIALS

Capecitabine was given orally twice daily Monday through Friday concurrently with RT. Oxaliplatin was given i.v. once weekly x 5 (for 5 weeks) starting the first day of RT. RT was given daily except on weekends and holidays at 1.8 Gy per fraction x 28. Escalation for capecitabine or oxaliplatin was to occur in cohorts of three patients until the maximum tolerated dose (MTD) was defined. Endorectal tumor biopsy samples were obtained before and on Day 3 of treatment to explore the effects of treatment on thymidine phosphorylase, thymidylate synthase, dihydropyrimidine dehydrogenase, DNA repair, and apoptosis.

RESULTS

Twelve patients were enrolled on this study. Two of 6 patients at dose level (DL) 1 (capecitabine 825 mg/m2 orally (p.o.) given twice daily (b.i.d.); oxaliplatin 50 mg/m2/week) had a dose-limiting diarrhea. One of 6 patients at DL (-)1 (capecitabine 725 mg/m2 p.o., b.i.d.; oxaliplatin 50 mg/m2/week) experienced-dose-limiting diarrhea. Three of 11 patients who underwent resection had a complete pathologic response. No remarkable variations in rectal tumor biologic endpoints were noted on Day 3 of treatment in comparison to baseline. However, a higher apotosis index was observed at baseline and on Day 3 in complete pathologic responders (no statistical analysis performed).

CONCLUSIONS

Capecitabine 725 mg/m2 p.o., twice daily in combination with oxaliplatin 50 mg/m2/week and RT 50.4 Gy in 28 fractions is the recommended dose for future studies.

The predictive value of apoptosis protease-activating factor 1 in rectal tumors treated with preoperative, high-dose-rate brachytherapy

BACKGROUND

The objective of this study was to assess the value of apoptosis protease-activating factor 1 (APAF-1) as a predictive marker of response in rectal tumors treated with preoperative, high-dose-rate endorectal brachytherapy.

METHODS

Immunohistochemistry for APAF-1 was performed on 94 rectal tumor biopsy specimens from patients who were treated on a preoperative, high-dose-rate brachytherapy protocol. Tumors were considered positive when > 10% of tumor cells were immunoreactive. The association between APAF-1 expression and tumor response was made using the chi-square test.

RESULTS

Forty-four tumors (43%) were positive for APAF-1. Thirty tumors had complete pathologic tumor regression after preoperative radiotherapy. Of these, 18 tumors were positive for APAF-1. A partial response occurred in 35 tumors. Eighteen tumors (51%) were positive for the protein. Only 8 of 29 nonresponsive tumors (28%) were immunoreactive for APAF-1. A significant association was found between complete tumor regression and positive APAF-1 status (P = 0.018). APAF-1 expression in partially responsive tumors was significantly greater than in nonresponsive tumors (P = 0.03).

CONCLUSIONS

APAF-1 expression in pretreatment rectal tumor biopsy specimens may be useful as a predictive marker of response to preoperative radiotherapy in patients with rectal carcinoma.

Plato, Sun Tsu, and the Art of War (on cancer). Can we learn from history?

Cancer, in all its guises is on the rise along with the population growth. While not the leading cause of death in the world, it may soon garner that unfortunate honor. In the US, it is second only to heart disease. The 'war on cancer' declared in the US by Richard Milhouse Nixon is not being won. At present, treatment modalities are limited to resection, immunotoxins, radiation, chemotherapy, genomeceuticals, and variations on those themes. It is anticipated that with the emerging human genome data, most of these areas will be expanded, with the possible exception of radiation. However, all these approaches have two things in common. First, they have met with limited success. Second, they all work around the similar idea of containment and eradication in situ of the disease. This paper presents an alternative and novel way of looking at the research and treatment options for cancer taking two lessons from history. First, is Plato's dialectic where 'truth' is uncovered by examining a situation from two opposite directions at once. Second, from Sun Tsu's treaty on the Art of War, where he recommends that when faced with a superior opponent, one method of dealing with the situation is to provoke them, anger them, cause them to move. The second tactic wears out the opponent and presents them in a more favorable situation for assault. It is suggested herein that perhaps cancer can be attacked by first assisting its growth, and causing metastasis to a location more favorable to attack with the common mechanisms cited above.