Rsf-1 expression in rectal cancer: with special emphasis on the independent prognostic value after neoadjuvant chemoradiation

Predictive biomarkers in radioresistant rectal cancer: a systematic review

BACKGROUND AND AIMS

The treatment of locally advanced rectal cancer often consists of neoadjuvant chemoradiotherapy followed by surgery. However, approximately 15% of patients show no response to this neoadjuvant chemoradiotherapy. This systematic review aimed to identify biomarkers of innate radioresistant rectal cancer.

METHOD

Through a systematic literature search, 125 papers were included and analyzed using ROBINS-I, a Cochrane risk of bias tool for non-randomized studies of interventions. Both statistically significant and nonsignificant biomarkers were identified. Biomarkers mentioned more than once in the results or biomarkers with a low or moderate risk of bias were included as the final results.

RESULTS

Thirteen unique biomarkers, three genetic signatures, one specific pathway, and two combinations of two or four biomarkers were identified. In particular, the connection between HMGCS2, COASY, and PI3K-pathway seems promising. Future scientific research should focus on further validating these genetic resistance markers.

ceRNA Networks: The Backbone Role in Neoadjuvant Chemoradiotherapy Resistance/Sensitivity of Locally Advanced Rectal Cancer

Approximately 40% of rectal cancers during initial diagnosis are identified as locally advanced rectal cancers (LARCs), for which the standardized treatment scenario is total mesorectal excision following neoadjuvant chemoradiotherapy (nCRT). nCRT can lead to discernible reductions in local relapse rate and distant metastasis rate in LARC patients, in whom previously inoperable tumors may potentially be surgically removed. However, only 4% to 20% cases can attain pathological complete response, and the remaining patients who are unresponsive to nCRT have to suffer from the side effects plus toxicities and may encounter poor survival outcomes due to the late surgical intervention. As such, employing potential biomarkers to differentiate responders from nonresponders before nCRT implementation appears to be the overarching goal. Well-defined competing endogenous RNA (ceRNA) networks include long noncoding RNA (lncRNA)-microRNA (miRNA)-mRNA and circRNA-miRNA-mRNA networks. As ceRNAs, lncRNAs, and circRNAs sponge miRNAs to indirectly suppress miRNAs downstream of oncogenic mRNAs or tumor-suppressive mRNAs. The abnormal expression of mRNAs regulates the nCRT-induced DNA damage repair process through pluralistic carcinogenic signaling pathways, thereby bringing about alterations in the nCRT resistance/sensitivity of tumors. Moreover, many molecular mechanisms relevant to cell proliferation, metastasis, or apoptosis of cancers (eg, epithelial-mesenchymal transition and caspase-9-caspase-3 pathway) are influenced by ceRNA networks. Herein, we reviewed a large group of abnormally expressed mRNAs and noncoding RNAs that are associated with nCRT resistance/sensitivity in LARC patients and ultimately pinpointed the backbone role of ceRNA networks in the molecular mechanisms of nCRT resistance/sensitivity.

RSF-1 siRNA Enhances Tumor Radiosensitivity in Cervical Cancer via Enhanced DNA Damage, Cell Cycle Redistribution, and Promotion of Apoptosis

Background

Remodeling and spacing factor-1 (RSF-1) is an identified tumor biomarker that is overexpressed in a variety of human cancers, but its effect on radiotherapy remains unclear. In this study, we aimed to explore the effect of RSF-1 siRNA on sensitizing cervical cancer cells to radiation and its underlying mechanism.

Methods

The mRNA and protein expression of RSF-1 in tissue and cells were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. Cell counting kit-8 (CCK-8) and colony formation assay were used to examine cell proliferation. Flow cytometry was used to analyzed the cell cycle and cell apoptosis. DNA damage was examined by the comet assay. ATM, ATR, CHK1, CHK2, H2AX, γH2AX and phosphorylated ATM, ATR, CHK1 and CHK2 were detected by Western blotting. γH2AX foci were demonstrated by immunofluorescence staining.

Results

RSF-1 was upregulated in cervical cancer tissue and decreased after effective treatment. RSF-1 siRNA in combination with radiation suppressed cell viability, redistributed cell cycles and also induced cell apoptosis in HeLa and SiHa cell lines. Further, knockdown of RSF-1 induced DNA damage by attenuating DNA repair capability, thereby sensitizing cervical cancer cells to radiation.

Conclusions

These data demonstrate that RSF-1 siRNA enhanced the sensitivity of radiotherapy, and targeting RSF-1 may be a promising approach for the development of novel radiosensitizing agents for the treatment of cervical cancer.

High RSF1 protein expression is an independent prognostic feature in prostate cancer

Background: Remodelling and spacing factor 1 (RSF1) is involved in the regulation of chromatin remodelling and represents a potential therapeutic target. High RSF1 expression has been linked to adverse tumour features in many cancer types, but its role in prostate cancer is uncertain.Methods: In this study, RSF1 expression was analysed by immunohistochemistry on a tissue microarray with 17,747 prostate cancers.Results: Nuclear RSF1 staining of 16,456 interpetable cancers was considered strong, moderate, weak and negative in 25.2%, 48.7%, 5.3% and 20.8% of cancers respectively. Positive RSF1 expression was associated with advanced tumour stage, high Gleason grade, lymph node metastasis (p < .0001 each), early biochemical recurrence (p < .0003) and more frequent in the ERG positive than in the ERG negative subset (88% versus 71%; p < .0001). Subset analysis revealed, that associations between RSF1 expression and unfavourable tumour phenotype and PSA recurrence were present in both subgroups but stronger in the ERG negative than in the ERG positive subset. The univariate Cox proportional hazard ratio for PSA recurrence-free survival for strong versus negative RSF1 expression was a weak 1.60 compared with 5.91 for the biopsy Gleason grade ≥4 + 4 versus ≤3 + 3. The positive association of RSF1 protein detection with deletion of 3p13, 10q23 (PTEN), 12p13, 16q23, and 17p13 (p < .0001 each) suggest a role of high RSF1 expression in the development of genomic instability.Conclusion: In summary, the results of our study identify RSF1 as an independent prognostic marker in prostate cancer with a particularly strong role in ERG negative cases.

Pathological Tumor Regression Grade Classifications in Gastrointestinal Cancers: Role on Patients' Prognosis

Preoperative chemotherapy or combined radiotherapy and chemotherapy (CRT), followed by surgery, represents the standard approach for locally advanced esophageal, gastric, and rectal carcinomas. To adequately evaluate the effects of neoadjuvant CRT in the resection specimens, several histopathologic tumor regression grade (TRG) scoring systems have been introduced into clinical practice. The primary goal of these TRG systems relies on a correct prognostic stratification of patients in the attempt to help clinical decision-making and influence surgical strategies, postoperative adjuvant therapies, and surveillance intensity. However, most TRG systems suffer from poor reproducibility and low interobserver concordance rates. Many efforts have been made in the identification of alternative, robust, simple, and universally accepted TRG scoring systems, which would help in the comparison of different treatment strategies and in the standardization of multimodal therapies. The aim of this review is to analyze the most commonly used TRG systems in gastrointestinal cancers highlighting their pitfalls and usefulness, depending on the tumor type.

Rsf‑1 regulates malignant melanoma cell viability and chemoresistance via NF‑κB/Bcl‑2 signaling

Remodeling and spacing factor 1 (Rsf-1) has been reported as overexpressed in numerous cancers; however, its expression, biological functions and mechanisms in malignant melanoma remain unknown. In the present study, the expression of Rsf-1 was investigated in 50 cases of malignant melanoma samples using immunohistochemistry. The results revealed that Rsf-1 expression was elevated in 38% of specimens. MTT, colony formation, Transwell and flow cytometry assays were performed to investigate the functions of Rsf-1. Knockdown of Rsf-1 in the MV3 and A375 melanoma cell lines decreased the viability, invasion and cell cycle transition of cells. Conversely, overexpression of Rsf-1 in M14 cells with low endogenous Rsf-1 expression induced opposing effects. Further analysis revealed that Rsf-1 knockdown decreased matrix metalloproteinase-2, cyclin E and phosphorylated-IκB expression. Additionally, Rsf-1 depletion reduced cisplatin resistance and significantly increased the cisplatin-associated apoptotic rate, whereas Rsf-1 overexpression exhibited opposing effects. Rsf-1 also maintained the mitochondrial membrane potential following cisplatin treatment. Analysis of apoptosis-associated proteins revealed that Rsf-1 positively regulated B-cell lymphoma 2 (Bcl-2), cellular inhibitor of apoptosis 1 (cIAP1) and cIAP2, and downregulated Bcl-2-associated X protein expression. Nuclear factor κ-light-chain-enhancer of activated B-cells (NF-κB) inhibition reversed the effects of Rsf-1 on Bcl-2. In conclusion, Rsf-1 was overexpressed in malignant melanoma and may contribute to the malignant behaviors of melanoma cells, possibly via the regulation of NF-κB signaling. Therefore, Rsf-1 may be a potential therapeutic target in the treatment of malignant melanoma.

Effects of RSF-1 on proliferation and apoptosis of breast cancer cells

Effect of interference with chromatin remodeling and spacing factor-1 (RSF-1) on proliferation and apoptosis of breast cancer cells was investigated. MCF-7 and SKBR-3 cells were cultured in vitro and were divided into 3 groups: control group, negative siRNA control group (NC) and RSF-1 siRNA group. Western blot analysis was used to detect the expression of RSF protein after interference. Cell Counting Kit-8 (CCK-8) method was used to detect the effect of RSF-1 siRNA on cell proliferation. Plate cloning assay was used to detect the effect of RSF-1 siRNA on cell clone formation ability. Annexin V/PI double staining method was used to detect the effect of RSF-1 siRNA on cell apoptosis. Effect of RSF-1 siRNA on nuclear factor-κB (NF-κB) and its downstream signaling pathway were detected by western blot analysis. Western blot analysis showed that RSF-1 siRNA significantly downregulated the expression of RSF-1 protein in MCF-7 and SKBR-3 cells at 72 h after transfection (P<0.01). Cell proliferation assay showed that RSF-1 siRNA significantly reduced the proliferation ability and clone formation ability of MCF-7 and SKBR-3 cells compared with the control group (P<0.01). Annexin V/PI double staining assay results showed that compared with the control group, RSF-1 siRNA significantly increased the apoptosis rate of MCF-7 and SKBR-3 cells (P<0.01). Helenalin and Rsf-1 siRNA significantly reduced the expression levels of p-p65, Bcl-2, and XIAP proteins (P<0.01). Interfering with the expression of RSF-1, gene can effectively inhibit the proliferation of MCF-7 and SKBR-3 cells and promote their apoptosis. RSF-1 can be used as a potential new therapeutic target for the treatment of breast cancer.

Epigenomic regulation of oncogenesis by chromatin remodeling

Disruption of the intricate gene expression program represents one of major driving factors for the development, progression and maintenance of human cancer, and is often associated with acquired therapeutic resistance. At the molecular level, cancerous phenotypes are the outcome of cellular functions of critical genes, regulatory interactions of histones and chromatin remodeling complexes in response to dynamic and persistent upstream signals. A large body of genetic and biochemical evidence suggests that the chromatin remodelers integrate the extracellular and cytoplasmic signals to control gene activity. Consequently, widespread dysregulation of chromatin remodelers and the resulting inappropriate expression of regulatory genes, together, lead to oncogenesis. We summarize the recent developments and current state of the dysregulation of the chromatin remodeling components as the driving mechanism underlying the growth and progression of human tumors. Because chromatin remodelers, modifying enzymes and protein-protein interactions participate in interpreting the epigenetic code, selective chromatin remodelers and bromodomains have emerged as new frontiers for pharmacological intervention to develop future anti-cancer strategies to be used either as single-agent or in combination therapies with chemotherapeutics or radiotherapy.

Overexpression of hSNF2H in glioma promotes cell proliferation, invasion, and chemoresistance through its interaction with Rsf-1

hSNF2H partners with Rsf-1 to compose the Rsf complex to regulate gene expression. Recent studies indicated that hSNF2H was overexpressed in several human cancers. However, its expression pattern and biological mechanism in glioma remain unexplored. In this study, we found that hSNF2H was overexpressed in 32 % of glioma specimens. hSNF2H overexpression correlated with advanced tumor grade (p = 0.0338) and Rsf-1 positivity in glioma tissues (p = 0.016). Small interfering RNA (siRNA) knockdown was performed in A172 and U87 cell lines. MTT, colony formation assay, and cell cycle analysis showed that knockdown of hSNF2H inhibited cell proliferation, colony formation ability, and cell cycle transition. Matrigel invasion assay showed that hSNF2H depletion inhibited invasive ability of glioma cells. In addition, we demonstrated that hSNF2H depletion decreased temozolomide resistance of A172 and U87 cell lines and increased temozolomide induced apoptosis. Furthermore, hSNF2H depletion decreased cyclin D1, cyclin E, p-Rb, MMP2, cIAP1, Bcl-2 expression, and phosphorylation of IκBα and p65, suggesting hSNF2H regulates apoptosis through NF-κB pathway. Immunoprecipitation showed that hSNF2H could interact with Rsf-1 in both cell lines. To validate the involvement of Rsf-1, we checked the change of its downstream targets in Rsf-1 depleted cells. In Rsf-1 depleted cells, changes of cyclin E, Bcl-2, and p-IκBα were not significant using hSNF2H siRNA treatment. In conclusion, our study demonstrated that hSNF2H was overexpressed in human gliomas and contributed to glioma proliferation, invasion, and chemoresistance through regulation of cyclin E and NF-κB pathway, which is dependent on its interaction with Rsf-1.

American Joint Committee on Cancer and College of American Pathologists regression grade: a new prognostic factor in rectal cancer

BACKGROUND

The American Joint Committee on Cancer and the College of American Pathologists provide guidelines for reporting pathologic response to neoadjuvant treatment of rectal cancer. The clinical relevance of these tumor regression grading guidelines is undefined.

OBJECTIVE

This study evaluates the prognostic significance of the American Joint Committee on Cancer/College of American Pathologists regression grading.

DESIGN

This is a retrospective cohort study based on data from a prospectively maintained colorectal cancer database. The cohorts were defined by American Joint Committee on Cancer/College of American Pathologists tumor regression grade.

SETTING

This study was performed at a single tertiary referral center.

PATIENTS

Five hundred thirty-eight patients with primary rectal adenocarcinoma who underwent neoadjuvant therapy between 1992 and 2012 were identified.

MAIN OUTCOME MEASURES

The primary outcome measures were overall and disease-free survival, cancer-specific mortality, and cumulative recurrence rate.

RESULTS

Five hundred thirty-eight patients were included, 105 of whom (19.5%) were American Joint Committee on Cancer/College of American Pathologists grade 0, 153 patients (28.4%) were grade 1, 181 patients (33.6%) were grade 2, and 99 (18.4%) were grade 3. Kaplan-Meier analysis revealed that American Joint Committee on Cancer/College of American Pathologists grade was associated with significant differences in overall survival (p < 0.001), disease-free survival (p < 0.001), and cumulative recurrence (p < 0.001). No local recurrences were observed in American Joint Committee on Cancer/College of American Pathologists grade 0 patients. Five-year overall survival rates were 89%, 74%, 63%, and 40% (p < 0.001); 5-year disease-free survival rates were 85%, 64%, 54%, and 33% (p < 0.001); and 5-year recurrence rates were 7%, 18%, 25%, and 33% (p <0.001) for American Joint Committee on Cancer/College of American Pathologists grades 0, 1, 2, and 3. After adjusting for significant covariates, including pathologic stage, American Joint Committee on Cancer/College of American Pathologists grade remained an independent predictor of overall survival (p < 0.001), disease-free survival (p < 0.001), and cumulative recurrence (p < 0.001) in Cox regression analyses.

LIMITATIONS

This was a retrospective study. There was a low local recurrence rate in our population, limiting the sensitivity of recurrence analyses.

CONCLUSIONS

This is the first study to delineate American Joint Committee on Cancer/College of American Pathologists regression grade as an independent oncologic prognostic factor. This information can be used in discussions with patients who have rectal cancer.

Overexpression of REG4 confers an independent negative prognosticator in rectal cancers receiving concurrent chemoradiotherapy

BACKGROUND AND OBJECTIVES

Neoadjuvant concurrent chemoradiotherapy (CCRT) followed by surgery is the standard treatment for locally advanced rectal cancer. Through data mining from published transcriptomic database, we identified Regenerating Gene Type IV (REG4) as the most significantly associated gene with resistance to CCRT. This study examined the prognostic impact of REG4 expression in patients with rectal cancer receiving neoadjuvant CCRT.

METHODS

REG4 immunohistochemistry was retrospectively assessed for pre-treatment biopsy specimens from 172 rectal cancer patients who received neoadjuvant CCRT followed by surgery without initial distant metastasis. The results were correlated with the clinicopathological variables, disease-specific survival (DSS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS), as well as γ-H2AX expression in post-treatment tumor samples.

RESULTS

High expression of REG4 was associated with advanced pre-treatment nodal status (P = 0.026), advanced post-treatment tumor status (P = 0.006), advanced post-treatment nodal status (P = 0.001), advanced post-treatment tumor stage (P < 0.001), and inferior tumor regression grade (P = 0.001). Of note, high expression of REG4 emerged as an adverse prognosticator for DSS (P = 0.0004), LRFS (P = 0.0009), and MeFS (P = 0.0254). After multivariate comparisons, it remained independently prognostic for worse DSS (hazard ratio [HR] = 2.731; P = 0.025) and LRFS (HR = 2.676; P = 0.029). High expression of REG4 was also negatively associated with γ-H2AX expression (P < 0.0001, r = -0.708).

CONCLUSIONS

High expression of REG4 is associated with poor therapeutic response, adverse outcome and an aggressive phenotype in rectal cancer patients treated with neoadjuvant CCRT, justifying REG4 is a surrogate marker to predict CCRT resistance.

Controversies in the pathological assessment of colorectal cancer

Pathologic assessment of colorectal cancer specimens plays an essential role in patient management, informing prognosis and contributing to therapeutic decision making. The tumor-node-metastasis (TNM) staging system is a key component of the colorectal cancer pathology report and provides important prognostic information. However there is significant variation in outcome of patients within the same tumor stage. Many other histological features such as tumor budding, vascular invasion, perineural invasion, tumor grade and rectal tumor regression grade that may be of prognostic value are not part of TNM staging. Assessment of extramural tumor deposits and peritoneal involvement contributes to TNM staging but there are some difficulties with the definition of both of these features. Controversies in colorectal cancer pathology reporting include the subjective nature of some of the elements assessed, poor reporting rates and reproducibility and the need for standardized examination protocols and reporting. Molecular pathology is becoming increasingly important in prognostication and prediction of response to targeted therapies but accurate morphology still has a key role to play in colorectal cancer pathology reporting.

Overexpression of CPS1 is an independent negative prognosticator in rectal cancers receiving concurrent chemoradiotherapy

Locally advanced rectal cancers are currently treated with neoadjuvant concurrent chemoradiotherapy (CCRT) followed by surgery, but stratification of risk and final outcomes remain suboptimal. In view of the fact that glutamine metabolism is usually altered in cancer, we profiled and validated the significance of genes involved in this pathway in rectal cancers treated with CCRT. From a published transcriptome of rectal cancers (GSE35452), we focused on glutamine metabolic process-related genes (GO:0006541) and found upregulation of carbamoyl phosphate synthetase 1 (CPS1) gene most significantly predicted poor response to CCRT. We evaluated the expression levels of CPS1 using immunohistochemistry to analyze tumor specimens obtained during colonoscopy from 172 rectal cancer patients. Expression levels of CPS1 were further correlated with major clinicopathological features and survivals in this validation cohort. To further confirm CPS1 expression levels, Western blotting was performed for human colon epithelial primary cell (HCoEpiC) and four human colon cancer cells, including HT29, SW480, LoVo, and SW620. CPS1 overexpression was significantly related to advanced posttreatment tumor (T3, T4; P = 0.006) and nodal status (N1, N2; P < 0.001), and inferior tumor regression grade (P = 0.004). In survival analyses, CPS1 overexpression was significantly associated with shorter disease-specific survival (DSS) and metastasis-free survival (MeFS). Furthermore, using multivariate analysis, it was also independently predictive of worse DSS (P = 0.021, hazard ratio = 2.762) and MeFS (P = 0.004, hazard ratio = 3.897). CPS1 protein expression, as detected by Western blotting, is more abundant in colon cancer cells than nonneoplastic HCoEpiC. Overexpression of CPS1 is associated with poor therapeutic response and adverse outcomes among rectal cancer patients receiving CCRT, justifying the potential theranostic value of CPS1 for such patients.

Galectin 9 and PINCH, novel immunotherapy targets of renal cell carcinoma: a rationale to find potential tumour antigens and the resulting cytotoxic T lymphocytes induced by the derived peptides

OBJECTIVE

To analyse and then generalize the mechanism by which partial or complete response is achieved among a limited number of patients with metastatic renal cell carcinoma (RCC) treated with interferon or interleukin-2.

MATERIALS AND METHODS

An expression library of RCC (clear-cell carcinoma) was screened using the sera of patients with metastatic RCC who benefited from partial or complete response to cytokine therapy, the postulation being that those remarkable responders obtained specific cellular immunity against RCC with the antibodies to react with the cancer antigen. Peripheral blood mononuclear-cells (PBMCs) from healthy volunteers were stimulated with the antigen-derived peptides to induce specific cytotoxic T lymphocytes (CTLs). Specific activities of CTLs were measured by ⁵¹Cr-releasing assay.

RESULTS

Among 15 positive clones isolated, two novel genes, galectin 9 and PINCH, were expressed at much higher levels in cancerous lesions than in normal tissues in all the patients with clear-cell carcinoma who were examined. Both HLA-A*2402-restricted and HLA-A*0201-restricted CTLs were induced by each antigen-derived peptide to exhibit specific and highly cytotoxic activities towards RCC cells. Specific CTLs were induced abundantly, as shown by flow cytometry analysis of the CTLs labelled with fluorescein isothiocyanate anti-CD107a and APC anti-CD8. The clonal expansion of the CTLs was shown by the clonality of T-cell receptor Vβ repertoires.

CONCLUSION

A novel approach based on clinical observations yielded promising tumour antigens as immunotherapy targets of RCC.

Overexpression of ANXA1 confers independent negative prognostic impact in rectal cancers receiving concurrent chemoradiotherapy

Neoadjuvant concurrent chemoradiation therapy (CCRT) is an increasingly common therapeutic strategy for rectal cancer. Clinically, it remains a major challenge to predict therapeutic response and patient outcomes after CCRT. Annexin I (ANXA1), encoded by ANXA1, is a Ca(2+)/phospholipid-binding protein that mediates actin dynamics and cellular proliferation, as well as suggesting tumor aggressiveness and predicting therapeutic response in certain malignancies. However, expression of ANXA1 has never been reported in rectal cancer receiving CCRT. This study examined the predictive and prognostic impact of ANXA1 expression in patients with rectal cancer following neoadjuvant CCRT. We identified ANXA1 as associated with resistance to CCRT through data mining from a published transcriptomic dataset. Its immunoexpression was retrospectively assessed using H scores on pre-treatment biopsies from 172 rectal cancer patients treated with neoadjuvant CCRT followed by curative surgery. Results were correlated with clinicopathological features, therapeutic response, tumor regression grade (TRG), and metastasis-free survival (MeFS), as well as local recurrent-free survival (LRFS) and disease-specific survival (DSS). High expression of ANXA1 was associated with advanced pre-treatment tumor status (T3, T4, p = 0.022), advanced pre-treatment nodal status (N1, N2, p = 0.004), advanced post-treatment tumor status (T3, T4, p < 0.001), advanced post-treatment nodal status (N1, N2, p = 0.001) and inferior TRG (p = 0.009). In addition, high expression of ANXA1 emerged as an adverse prognosticator for DSS (p < 0.0001), LRFS (p = 0.0001) and MeFS (p = 0.0004). Moreover, high expression of ANXA1 also remained independently prognostic of worse DSS (hazard ratio [HR] = 3.998; p = 0.007), LRFS (HR = 3.206; p = 0.028) and MeFS (HR = 3.075; p = 0.017). This study concludes that high expression of ANXA1 is associated with poor therapeutic response and adverse outcomes in rectal cancer patients treated with neoadjuvant CCRT.

Chromosomal instability portends superior response of rectal adenocarcinoma to chemoradiation therapy

BACKGROUND

Persistent chromosome segregation errors represent a conspicuous feature of human neoplasms. It is widely accepted that this chromosomal instability is associated with poor prognosis; however, its effect on therapeutic response is a matter of conjecture.

METHODS

Here, the role of chromosome segregation errors in the response of patients with rectal adenocarcinoma to chemoradiation therapy (CRT) was examined. Pretreatment samples from 62 patients were surveyed for evidence of chromosome mis-segregation and mis-segregation frequency was correlated to the pathological response to CRT as determined by the tumor regression grade after surgical resection of irradiated tumors.

RESULTS

Surprisingly, it was found that errors in chromosome segregation predicted enhanced pathological response of rectal adenocarcinoma to CRT (odds ratio, 3.9; P = .02). Furthermore, tumor response inversely correlated with the frequency of cells that exhibited segregation errors during anaphase (correlation coefficient, 0.94; P < .05). Strikingly, elevated chromosome mis-segregation combined with decreased levels of the DNA damage repair protein Mre11 portended a markedly enhanced response (odds ratio, 54.0; P = .008).

CONCLUSIONS

The results of the current study demonstrate that chromosomal instability is a favorable predictor of response to CRT in patients with locally invasive rectal adenocarcinoma. Therefore, the authors propose that downstream structural damage to chromosomes resulting from segregation errors potentiates the effect of DNA-damaging therapies and synergizes with deficiencies in the DNA repair machinery. This work identifies a novel mechanistic marker that foretells treatment response to CRT and suggests that concomitant targeting of whole-chromosome segregation and DNA repair may constitute an effective therapeutic strategy.

Future directions in combined modality therapy for rectal cancer: reevaluating the role of total mesorectal excision after chemoradiotherapy

Most patients who develop rectal cancer present with locoregionally advanced (T3 or node-positive) disease. The standard management of locoregionally advanced rectal cancer is neoadjuvant concurrent chemoradiotherapy (nCRT), followed by radical resection (low-anterior resection or abdominoperineal resection with total mesorectal excision). Approximately 15% of patients can have a pathologic complete response (pCR) at the time of surgery, indicating that some patients can have no detectable residual disease after nCRT. The actual benefit of surgery in this group of patients is unclear. It is possible that omission of surgery in these patients, termed selective nonoperative management, can limit the toxicities associated with standard, multimodal combined modality therapy without compromising disease control. In this review, we discuss the clinical experiences to date using selective nonoperative management and various attempts at escalation of nCRT to improve the number of patients who have a pCR. We also explore several clinical, laboratory, imaging, histopathologic, and genetic biomarkers that have been tested as tools to predict which patients are most likely to have a pCR after nCRT.

Rsf-1, a chromatin remodelling protein, interacts with cyclin E1 and promotes tumour development

Chromosome 11q13.5 containing RSF1 (HBXAP), a gene involved in chromatin remodelling, is amplified in several human cancers including ovarian carcinoma. Our previous studies demonstrated requirement of Rsf-1 for cell survival in cancer cells, which contributed to tumour progression; however, its role in tumourigenesis has not yet been elucidated. In this study, we co-immunoprecipitated proteins with Rsf-1 followed by nanoelectrospray mass spectrometry and identified cyclin E1, besides SNF2H, as one of the major Rsf-1 interacting proteins. Like RSF1, CCNE1 is frequently amplified in ovarian cancer, and both Rsf-1 and cyclin E1 were found co-up-regulated in ovarian cancer tissues. Ectopic expression of Rsf-1 and cyclin E1 in non-tumourigenic TP53(mut) RK3E cells led to an increase in cellular proliferation and tumour formation by activating cyclin E1-associated kinase (CDK2). Tumourigenesis was not detected if either cyclin E1 or Rsf-1 was expressed, or they were expressed in a TP53(wt) background. Domain mapping showed that cyclin E1 interacted with the first 441 amino acids of Rsf-1. Ectopic expression of this truncated domain significantly suppressed G1/S-phase transition, cellular proliferation, and tumour formation of RK3E-p53(R175H) /Rsf-1/cyclin E1 cells. The above findings suggest that Rsf-1 interacts and collaborates with cyclin E1 in neoplastic transformation and TP53 mutations are a prerequisite for tumour-promoting functions of the RSF/cyclin E1 complex.

SKP2 overexpression is associated with a poor prognosis of rectal cancer treated with chemoradiotherapy and represents a therapeutic target with high potential

The S-phase kinase-associated protein 2 (SKP2) oncoprotein is an E3 ubiquitin ligase. Overexpression of SKP2 was found in various human cancers, including colorectal cancers, but its potential role as a prognostic marker after neoadjuvant chemoradiotherapy (CRT) and for therapeutic intervention in rectal cancers is unknown. This study examined the correlation of SKP2 expression in the prognosis of rectal cancer patients and the viability of colorectal cancer cells treated with CRT. SKP2 immunoexpression was retrospectively assessed in pretreatment biopsies of 172 rectal cancer patients treated with neoadjuvant CRT followed by surgery. Results were correlated with clinicopathological features, therapeutic responses, and patient survival. Pharmacologic assays were used to evaluate the therapeutic relevance of Bortezomib in two colorectal cancer cell lines (HT-29 and SW480). High expression of SKP2 was correlated with the advanced Post-Tx nodal status (p = 0.002), Post-Tx International Union for Cancer Control stage (p = 0.002), and a lower-degree tumor regression grade (p < 0.001). Moreover, high expression of SKP2 (p = 0.027, hazard ratio 3.21) was an independent prognostic factor for local recurrence-free survival. In vitro, Bortezomib downregulated SKP2 expression, induced caspase activation, and decreased the viability of colorectal cancer cells with or without a combination with fluorouracil. Bortezomib also promoted caspase activation and gamma-H2AX formation in colorectal cancer cells concurrently treated with CRT. High expression of SKP2 was associated with a poor therapeutic response and adverse outcomes in rectal cancer patients treated with neoadjuvant CRT. In the presence of chemotherapy with or without radiotherapy, the promoted sensitivity of colorectal cancer cells to Bortezomib with an SKP2-repressing effect indicated that it is a potential therapeutic target.