Analysis of histological therapeutic effect, apoptosis rate and p53 status after combined treatment with radiation, hyperthermia and 5-fluorouracil suppositories for advanced rectal cancers

p53 dynamics in single cells are temperature-sensitive

Cells need to preserve genome integrity despite varying cellular and physical states. p53, the guardian of the genome, plays a crucial role in the cellular response to DNA damage by triggering cell cycle arrest, apoptosis or senescence. Mutations in p53 or alterations in its regulatory network are major driving forces in tumorigenesis. As multiple studies indicate beneficial effects for hyperthermic treatments during radiation- or chemotherapy of human cancers, we aimed to understand how p53 dynamics after genotoxic stress are modulated by changes in temperature across a physiological relevant range. To this end, we employed a combination of time-resolved live-cell microscopy and computational analysis techniques to characterise the p53 response in thousands of individual cells. Our results demonstrate that p53 dynamics upon ionizing radiation are temperature dependent. In the range of 33 °C to 39 °C, pulsatile p53 dynamics are modulated in their frequency. Above 40 °C, which corresponds to mild hyperthermia in a clinical setting, we observed a reversible phase transition towards sustained hyperaccumulation of p53 disrupting its canonical response to DNA double strand breaks. Moreover, we provide evidence that mild hyperthermia alone is sufficient to induce a p53 response in the absence of genotoxic stress. These insights highlight how the p53-mediated DNA damage response is affected by alterations in the physical state of a cell and how this can be exploited by appropriate timing of combination therapies to increase the efficiency of cancer treatments.

Germline and somatic genetic predictors of pathological response in neoadjuvant settings of rectal and esophageal cancers: systematic review and meta-analysis

Oncologists have pointed out an urgent need for biomarkers that can be useful for clinical application to predict the susceptibility of patients to preoperative therapy. This review collects, evaluates and combines data on the influence of reported somatic and germline genetic variations on histological tumor regression in neoadjuvant settings of rectal and esophageal cancers. Five hundred and twenty-seven articles were identified, 204 retrieved and 61 studies included. Among 24 and 14 genetic markers reported for rectal and esophageal cancers, respectively, significant associations in meta-analyses were demonstrated for the following markers. In rectal cancer, major response was more frequent in carriers of the TYMS genotype 2 R/2 R-2 R/3 R (rs34743033), MTHFR genotype 677C/C (rs1801133), wild-type TP53 and KRAS genes. In esophageal cancer, successful therapy appeared to correlate with wild-type TP53. These results may be useful for future research directions to translate reported data into practical clinical use.

P53 status as a predictive biomarker for patients receiving neoadjuvant radiation-based treatment: a meta-analysis in rectal cancer

Background

Numerous studies have yielded inconsistent results regarding the relationship between p53 status and the response to neoadjuvant radiation-based therapy in patients with rectal cancer. We conducted a meta-analysis to clarify the relationship between p53 status and response to radiation-based therapy in rectal cancer.

Methods/Findings

A total of 30 previously published eligible studies including 1,830 cases were identified and included in this meta-analysis. Wild-type form of p53 status (low expression of p53 protein and/or wild-type p53 gene) was associated with pathologic response in rectal cancer patients who received neoadjuvant radiation-based therapy (good response: risk ratio [RR] = 1.30; 95% confidence intervals [CI] = 1.14–1.49; p<0.001; complete response RR = 1.65; 95% CI = 1.19–2.30; p = 0.003; poor response RR = 0.85; 95% CI = 0.75–0.96; p = 0.007). In further stratified analyses, this association remained for sub-groups of good and poor response in neoadjuvant radiotherapy (RT) setting, good and complete response in chemoradiotherapy (CRT) setting. And the association between response and the presence of p53 gene mutations was stronger than that between response and protein positivity.

Conclusion

The results of the present meta-analysis indicate that P53 status is a predictive factor for response in rectal cancer patient undergoing neoadjuvant radiation-based therapy.

Comparison of genomics and functional imaging from canine sarcomas treated with thermoradiotherapy predicts therapeutic response and identifies combination therapeutics

PURPOSE

While hyperthermia is an effective adjuvant treatment to radiotherapy, we do not completely understand the nature of the response heterogeneity.

EXPERIMENTAL DESIGN

We performed gene expression analysis of 22 spontaneous canine sarcomas before and after the first hyperthermia treatment administered as an adjuvant to radiotherapy. In parallel, diffusion-weighted MRI (DWI) was done prior to the treatment course and at the end of therapy.

RESULTS

From the integrative analysis of gene expression and DWI, we identified significant correlation between tumor responses with genes involved in VEGF signaling, telomerase, DNA repair, and inflammation. The treatment-induced changes in gene expression identified 2 distinct tumor subtypes with significant differences in their gene expression and treatment response, as defined by changes in DWI. The 2 tumor subtypes could also be readily identified by pretreatment gene expression. The tumor subtypes, with stronger expression response and DWI increase, had higher levels of HSP70, POT1, and centrosomal proteins, and lower levels of CD31, vWF, and transferrin. Such differential gene expression between the 2 subtypes was used to interrogate connectivity map and identify linkages to an HSP90 inhibitor, geldanamycin. We further validated the ability of geldanamycin to enhance cell killing of human tumor cells with hyperthermia and radiotherapy in clonogenic assays.

CONCLUSIONS

To our knowledge, this is one of the first successful attempts to link changes in gene expression and functional imaging to understand the response heterogeneity and identify compounds enhancing thermoradiotherapy. This study also demonstrates the value of canine tumors to provide information generalizable to human tumors.

Chromosomal copy number changes of locally advanced rectal cancers treated with preoperative chemoradiotherapy

Standard treatment of rectal cancer patients comprises preoperative chemoradiotherapy followed by radical surgery. However, clinicians are faced with the problem that response rates vary from one individual to another. Predictive biomarkers would therefore be helpful. To identify genomic imbalances that might assist in stratifying tumors into responsive or nonresponsive categories, we used metaphase comparative genomic hybridization to prospectively analyze pretherapeutic biopsies from 42 patients with locally advanced rectal cancers. These patients were subsequently treated with 5-fluorouracil-based preoperative chemoradiotherapy. Based on downsizing of the T-category, 21 rectal cancers were later classified as responsive, while the other 21 were nonresponsive. Comparing these two groups, we could show that gains of chromosomal regions 7q32 approximately q36 and 7q11 approximately q31, as well as amplifications of 20q11 approximately q13, were significantly associated with responsiveness to preoperative chemoradiotherapy (P<0.05). However, the probability of detecting these copy number changes by chance is high (P=0.21). Our primary results suggest that pretherapeutic evaluation of chromosomal copy number changes may be of value for response prediction of rectal cancers to preoperative chemoradiotherapy. This will require validation in a larger cohort of patients.

Pathological and molecular predictors of the response of rectal cancer to neoadjuvant radiochemotherapy

AIMS

The prediction of sensitivity and resistance to neoadjuvant therapy has great potential value for many tumour sites. A neoadjuvant regimen is increasingly the gold standard in rectal cancer management and the aim of this review was to highlight predictive markers currently assessed and evaluate their clinical utility.

METHODS

A systematic search of Medline was conducted using the following keywords 'colorectal', 'neoadjuvant', 'molecular', 'predict' and 'radiotherapy'. Original manuscripts from all relevant listings were sourced. These were hand searched for further articles of relevance.

RESULTS

Conventional indices including tumour stage and grade were unable to predict histological response. Immunohistochemical assessment of P53 gene, Bcl 2, Bax and microsatellite instability are of no predictive value. Studies utilising molecular response predictors from archival pre-treatment tumour tissues have identified several promising predictive markers including p21, spontaneous apoptosis and direct sequencing of the p53 gene. Global gene expression from fresh pre-treatment tissue using cDNA microarray has only recently been assessed but identified expression differences between 54 genes and was able to predict response with 78% sensitivity and 86% specificity.

CONCLUSIONS

Currently there are no clinically useful predictors of response based on standard pathological assessment and immunocytochemistry. Direct gene sequencing of p53, studies of apoptosis and global gene sequencing may hold promise.

High intrinsic apoptosis, but not radiation-induced apoptosis, predicts better survival in rectal carcinoma patients

PURPOSE

An important feature of malignant tumors is the disturbance in the balance between proliferation and cell death. We evaluated the relevance of intrinsic and radiation-induced apoptosis and proliferation for prognosis in rectal cancer patients.

METHODS AND MATERIALS

Patients were selected from a study that randomized for preoperative radiotherapy (RT). Apoptosis and proliferation were scored using specific antibodies in immunohistochemistry. The number of positive cells per square millimeter of carcinoma cells was determined in 98 randomly selected tumors, of which 45 had been irradiated. For the survival analyses, a cohort of 104 patients without positive circumferential resection margins was selected.

RESULTS

In nonirradiated patients, high levels of intrinsic apoptosis correlated with better local control (p = 0.04) and better cancer-specific survival (p = 0.02). RT increased the median amount of apoptosis from 10.8 to 21.5 cells/mm(2) (p = 0.004), but this was not predictive for survival. The amount of proliferative cells was not altered after RT and had no influence on prognosis.

CONCLUSIONS

Intrinsic apoptosis correlated with both local control and cancer-specific survival, but proliferation was not predictive for prognosis. However, although RT increased apoptosis, its prognostic value was lost after RT. This is possibly because in rectal cancer, the proliferative status of tumors is always high and the aggressiveness of the tumor is determined by the number of "spontaneous" apoptotic tumor cells.

Spontaneous and radiation-induced apoptosis in colorectal carcinoma cells with different intrinsic radiosensitivities: survivin as a radioresistance factor

BACKGROUND

Spontaneous apoptosis has been shown to predict tumor response to radiochemotherapy in rectal cancer in vivo. It remains to be elucidated, however, which genetic profile determines whether a tumor is more or less prone to apoptosis. Recently, a novel member of the inhibitor of apoptosis protein family, designated survivin, was identified. We investigated the impact of survivin expression on tumor cell apoptosis in three colorectal cell lines of different intrinsic radiosensitivities.

METHODS AND MATERIALS

Survivin protein expression was measured by Western blot analysis, and survivin mRNA expression by quantitative TaqMan reverse transcription polymerase chain reaction, both in untreated cell and after irradiation with 2 and 8 Gy. The expression profile was then correlated to spontaneous and radiation-induced apoptosis (Tunel-Assay, DAPI-staining) in three colorectal cell lines of low (SW 480), intermediate (HCT-15), and high radiosensitivity (SW 48), as determined by the colony-forming assay.

RESULTS

In vitro analysis revealed higher spontaneous and higher radiation-induced apoptosis rates in the radiosensitive line (SW 48), as compared with the more resistant line (SW 480). In Western blot analysis and in TaqMan analysis, SW 480 was characterized by a higher spontaneous expression and a pronounced induction of survivin 48 h after irradiation, whereas survivin expression was low when untreated and not increased after irradiation in the most radiosensitive line SW 48. HCT-15 was intermediate, both with respect to the level of survivin mRNA and protein expression.

CONCLUSION

The inverse correlation of survivin-expression with spontaneous and radiation-induced apoptosis suggests that survivin is an important inhibitor of apoptosis in colorectal cancer cell lines. Analysis of survivin mRNA or protein expression may therefore provide predictive information on radio- and chemoresistance of individual colorectal tumors.

Apoptosis as a cellular predictor for histopathologic response to neoadjuvant radiochemotherapy in patients with rectal cancer

BACKGROUND

Tumor shrinkage by preoperative radiochemotherapy (RCT) can markedly improve surgery in locally advanced (T4) rectal cancer with clear resection margins and may enable sphincter preservation in low-lying tumors. However, tumor response varies considerably, even among tumors treated according to the same protocol. If one is able to identify patients with highly radio-responsive tumors at the time of diagnosis, a selective and individualized policy of preoperative RCT might be pursued.

METHODS

The apoptotic index (AI), Ki-67, p53, and bcl-2 were evaluated by immunohistochemistry on pretreatment biopsies from 44 patients treated uniformly according to a prospective neoadjuvant RCT protocol (CAO/AIO/ARO-94). Treatment response was assessed histopathologically in the resected surgical specimen, using a five-point grading system. Expression of each marker was correlated with tumor response and relapse-free survival after curative surgery.

RESULTS

Tumors with complete (n = 3) or good (n = 28) response to RCT showed significantly higher pretreatment levels of apoptosis (mean AI: 2.06%) than tumors with moderate (n = 7), minimal (n = 5), or no regression (n = 1) from RCT (AI: 1.44%, p = 0.003). The AI was significantly related to Ki-67 (p = 0.05), but not to p53 and bcl-2 status. Tumor regression and AI best predicted relapse-free survival after combined modality treatment and curative surgery.

CONCLUSION

Spontaneous apoptosis in rectal cancer may serve as an important predictor of tumor regression from RCT in rectal cancer and as a significant prognosticator of relapse-free survival. Thus, this molecular marker may finally help to tailor therapy with regard to (neo-) adjuvant treatment of rectal cancer.

Clinical application of hyperthermia combined with anticancer drugs for the treatment of solid tumors

BACKGROUND

Hyperthermia is one of the modalities used to treat various forms of malignancies, including esophageal, stomach, or rectal cancers.

METHODS

The basic mechanism of synergism between hyperthermia and anticancer drugs, as well as the clinical result of hyperthermia for the treatment of gastrointestinal malignancy, was reviewed.

RESULTS

Hyperthermia exerts a cytotoxic effect in combination with various mechanisms. Hyperthermia is applied in combination with chemotherapy and/or radiotherapy in the clinical setting. Among the anticancer drugs that are synergistic with hyperthermia is cisplatin, which is prevalent for clinical application. The mechanism of enhanced cytotoxicity of cisplatin includes increased intracellular drug accumulation, increased platinum-DNA adducts, and inhibition of DNA repair. At our institute, hyperthermochemoradiotherapy was conducted as a neoadjuvant therapy for either operative cases or as a palliative therapy for unresectable cases for esophageal and rectal cancers. In both situations, hyperthermochemoradiotherapy showed an excellent benefit in both the control of local recurrence and and in an improvement in patient survival. Regarding gastric cancer, the most popular application of hyperthermia was the intraoperative hyperthermic peritoneal lavage with cisplatin. This treatment modality demonstrated a better control of the disseminated lesion. Regarding the factors that influence thermosensitivity, in vitro experiments demonstrated the heat-shock proteins or tumor suppressor gene p53 to be related to thermosensitivity. In the clinical setting, these factors remain to be firmly established as predictive factors for thermosensitivity.

CONCLUSIONS

It is evident that hyperthermia was effective in the control of far-advanced gastrointestinal malignancies. When more reliable factors for the prediction of the treatment response can be established, the standard guidelines for the application of hyperthermia can then be made.

p53, BCL-2, and Ki-67 expression according to tumor response after concurrent chemoradiotherapy for advanced rectal cancer

BACKGROUND

Concurrent chemoradiotherapy (CCRT) for locally advanced rectal cancer is an important modality for curative resection, but tumors show wide spectrum response. The purpose of this study was to investigate any correlation among related genetic mutations, proliferative index, and tumor response after CCRT.

METHODS

This study included 23 patients with rectal cancer, who were preoperatively staged as at least T3 N1 or T4 (determined by transrectal ultrasonography and MRI). Enrolled patients were given 5-FU 450 mg/m2/day and leucovorin 20 mg/m2/day intravenously for 5 days during weeks 1 and 5 of radiotherapy (45-54 Gy). Surgical resection was performed 4 weeks after completion of the scheduled treatment. Tumor response was classified as CR (complete response), PR (partial response: 50% diminution of tumor volume and downstaging), and NR (no response). Paraffin-embedded tissue obtained before chemoradiotherapy was studied by immunohistochemical staining for p53, BCL-2, and Ki-67. The extent of tumor response was correlated with proliferative activity and was measured by immunostaining Ki-67 proliferative antigen and the expression of p53 and BCL-2 oncoproteins.

RESULTS

All patients were resectable. CR was obtained in 4 patients, PR in 10 patients, and NR in 9 patients. The p53 mutation was noted in 16 patients: NR in 5 patients, PR in 9 patients, and CR in 2 patients (P = .638). BCL-2 expression was noted in 11 patients: NR in 4 patients, PR in 3 patients, and CR in 4 patients (P = .799). The Ki-67 labeling index was NR: 615.4+/-47.2; PR: 663.2+/-20.4; and CR: 765.5+/-58.3 (CR + PR vs. NR, P = .029).

CONCLUSIONS

Immunohistochemical expression of p53 and BCL-2 does not correlate with tumor response after CCRT, but Ki-67 labeling may be a useful parameter for radiosensitive tumors selected for CCRT.

Apoptosis in oncology

Apoptosis is a complex process involving a large array of genes and mutation of any of these genes may lead to malignancy formation. Re-acquirement of FasL by tumor cells may enable them to evade the surveillance of immune system and thus contributes to the growth of tumor. Apart from traditional therapies, inducing apoptosis of tumor cell by new methods employing death receptor ligands and making use of Fas counterattack is also being developed.