Dynamic expression profile of p21WAF1/CIP1 and Ki-67 predicts survival in rectal carcinoma treated with preoperative radiochemotherapy

p21 as a Predictor and Prognostic Indicator of Clinical Outcome in Rectal Cancer Patients

The cell cycle plays a key and complex role in the development of human cancers. p21 is a potent cyclin-dependent kinase inhibitor (CDKI) involved in the promotion of cell cycle arrest and the regulation of cellular senescence. Altered p21 expression in rectal cancer cells may affect tumor cells' behavior and resistance to neoadjuvant and adjuvant therapy. Our study aimed to ascertain the relationship between the differential expression of p21 in rectal cancer and patient survival outcomes. Using tissue microarrays, 266 rectal cancer specimens were immunohistochemically stained for p21. The expression patterns were scored separately in cancer cells retrieved from the center and the periphery of the tumor; compared with clinicopathological data, tumor regression grade (TRG), disease-free, and overall survival. Negative p21 expression in tumor periphery cells was significantly associated with longer overall survival upon the univariate (p = 0.001) and multivariable analysis (p = 0.003, HR = 2.068). Negative p21 expression in tumor periphery cells was also associated with longer disease-free survival in the multivariable analysis (p = 0.040, HR = 1.769). Longer overall survival times also correlated with lower tumor grades (p= 0.011), the absence of vascular and perineural invasion (p = 0.001; p < 0.005), the absence of metastases (p < 0.005), and adjuvant treatment (p = 0.009). p21 expression is a potential predictive and prognostic biomarker for clinical outcomes in rectal cancer patients. Negative p21 expression in tumor periphery cells demonstrated significant association with longer overall survival and disease-free survival. Larger prospective studies are warranted to investigate the ability of p21 to identify rectal cancer patients who will benefit from neoadjuvant and adjuvant therapy.

Bottom-Up Approach to the Discovery of Clinically Relevant Biomarker Genes: The Case of Colorectal Cancer

Traditional approaches to genome-wide marker discovery often follow a common top-down strategy, where a large scale ‘omics’ investigation is followed by the analysis of functional pathways involved, to narrow down the list of identified putative biomarkers, and to deconvolute gene expression networks, or to obtain an insight into genetic alterations observed in cancer. We set out to investigate whether a reverse approach would allow full or partial reconstruction of the transcriptional programs and biological pathways specific to a given cancer and whether the full or substantially expanded list of putative markers could thus be identified by starting with the partial knowledge of a few disease-specific markers. To this end, we used 10 well-documented differentially expressed markers of colorectal cancer (CRC), analyzed their transcription factor networks and biological pathways, and predicted the existence of 193 new putative markers. Incredibly, the use of a validation marker set of 10 other completely different known CRC markers and the same procedure resulted in a very similar set of 143 predicted markers. Of these, 138 were identical to those found using the training set, confirming our main hypothesis that a much-expanded set of disease markers can be predicted by starting with just a small subset of validated markers. Further to this, we validated the expression of 42 out of 138 top-ranked predicted markers experimentally using qPCR in surgically removed CRC tissues. We showed that 41 out of 42 mRNAs tested have significantly altered levels of mRNA expression in surgically excised CRC tissues. Of the markers tested, 36 have been reported to be associated with aspects of CRC in the past, whilst only limited published evidence exists for another three genes (BCL2, PDGFRB and TSC2), and no published evidence directly linking genes to CRC was found for CCNA1, SHC1 and TGFB3. Whilst we used CRC to test and validate our marker discovery strategy, the reported procedures apply more generally to cancer marker discovery.

Personalized Medicine-Current and Emerging Predictive and Prognostic Biomarkers in Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer diagnosed worldwide and is heterogeneous both morphologically and molecularly. In an era of personalized medicine, the greatest challenge is to predict individual response to therapy and distinguish patients likely to be cured with surgical resection of tumors and systemic therapy from those resistant or non-responsive to treatment. Patients would avoid futile treatments, including clinical trial regimes and ultimately this would prevent under- and over-treatment and reduce unnecessary adverse side effects. In this review, the potential of specific biomarkers will be explored to address two key questions—1) Can the prognosis of patients that will fare well or poorly be determined beyond currently recognized prognostic indicators? and 2) Can an individual patient’s response to therapy be predicted and those who will most likely benefit from treatment/s be identified? Identifying and validating key prognostic and predictive biomarkers and an understanding of the underlying mechanisms of drug resistance and toxicity in CRC are important steps in order to personalize treatment. This review addresses recent data on biological prognostic and predictive biomarkers in CRC. In addition, patient cohorts most likely to benefit from currently available systemic treatments and/or targeted therapies are discussed in this review.

Prognostic Significance of Clinicopathological and Molecular Features After Neoadjuvant Chemoradiotherapy in Rectal Cancer Patients

BACKGROUND/AIM

This study evaluated clinicopathological and molecular features and their prognostic impact on patients with locally advanced rectal cancer (LARC) who received preoperative chemoradiotherapy (CRT).

PATIENTS AND METHODS

We retrospectively gathered data from 284 patients with LARC who underwent total mesorectal excision (TME) after CRT.

RESULTS

In the univariate analysis, lower yield pathologic T (ypT) category, yield pathologic N (ypN) category, yield pathologic TNM (ypTNM) stage, as well as the absence of lymphovascular invasion (LVI) and perineural invasion (PNI), were significantly associated with better disease-free survival (DFS) and overall survival (OS). Meanwhile, the expression of Ki-67, p53, and the mismatch repair (MMR) status showed no association with clinical outcomes. A multivariate survival analysis revealed that ypT category and LVI were independent prognostic factors of a worse DFS (HR=3.081, p-value=0.001; HR=2.818, p-value=0.030) and OS (HR=3.158, p-value=0.006; HR=3.837, p-value=0.014).

CONCLUSION

The ypT category and the presence of LVI were found to be prognostic factors for patients with LARC after CRT followed by TME.

Definitive radiotherapy or chemoradiotherapy for distal rectal cancer with early stage of cT1-2N0

Objectives: Patients with early-stage distal rectal cancer, if treated with radical surgery, usually suffer a poor quality of life. Definitive radiotherapy or chemoradiotherapy may be another treatment option for them. The aim of this study was to evaluate the role of definitive external beam radiotherapy or chemoradiotherapy in treating distal rectal cancer with stage cT1-2N0.

Methods: We performed a retrospective study of 231 distal rectal cancer patients who were staged as cT1-2N0 from March 2002 to March 2015. All patients were treated by definitive radiotherapy or chemoradiotherapy. Overall survival (OS), progression-free survival (PFS), and short-term efficacy were analyzed. Multivariate analysis was performed to explore clinical factors significantly associated with PFS, local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) for the whole group.

Results: For the whole group, 135 patients (58.4%) achieved clinical complete response (cCR). The 5-year OS, PFS, and LRFS were 86.19%, 83.30%, and 92.50%, respectively. Patients with cCR acquired better survival than those with non-cCR. In multivariable analysis, it revealed that clinical stage, carcinoembryonic antigen (CEA level) and concurrent chemotherapy were independent predictors of PFS.

Conclusion: Definitive radiotherapy or chemoradiotherapy may be feasible in some early-stage distal rectal cancer regarding its favorable efficacy.

Prognostic Value of Mismatch Repair Genes for Patients With Colorectal Cancer: Meta-Analysis

DNA mismatch repair was proposed to play a pivotal role in the development and prognosis of colorectal cancer. However, the prognostic value of mismatch repair on colorectal cancer is still unknown. The PubMed, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched. The articles about mismatch repair (including hMLH1, hMSH2, hMSH3, hMSH6, hPMSH1, and hPMSH2) deficiency for the prognosis of patients with colorectal cancer were included in the study. The hazard ratio and its 95% confidence interval were used to measure the impact of mismatch repair deficiency on survival time. Twenty-one articles were included. The combined hazard ratio for mismatch repair deficiency on overall survival was 0.59 (95% confidence interval: 0.50-0.69) and that on disease-free survival was 0.57 (95% confidence interval: 0.43-0.75). In subgroup analysis, there were a significant association between overall survival and mismatch repair deficiency in Asian studies (hazard ratio: 0.67; 95% confidence interval: 0.50-0.91) and Western studies (hazard ratio: 0.56; 95% confidence interval: 0.46-0.67). For disease-free survival, the hazard ratios in Asian studies and Western studies were 0.55 (95% confidence interval: 0.38-0.81) and 0.62 (95% confidence interval: 0.50-0.78), respectively. Our meta-analysis indicated that mismatch repair could be used to evaluate the prognosis of patients with colorectal cancer.

Cytoplasmic p21 Mediates 5-Fluorouracil Resistance by Inhibiting Pro-Apoptotic Chk2

The oncogenic cytoplasmic p21 contributes to cancer aggressiveness and chemotherapeutic failure. However, the molecular mechanisms remain obscure. Here, we show for the first time that cytoplasmic p21 mediates 5-Fluorouracil (5FU) resistance by shuttling p-Chk2 out of the nucleus to protect the tumor cells from its pro-apoptotic functions. We observed that cytoplasmic p21 levels were up-regulated in 5FU-resistant colorectal cancer cells in vitro and the in vivo Chorioallantoic membrane (CAM) model. Kinase array analysis revealed that p-Chk2 is a key target of cytoplasmic p21. Importantly, cytoplasmic form of p21 mediated by p21^T145D transfection diminished p-Chk2-mediated activation of E2F1 and apoptosis induction. Co-immunoprecipitation, immunofluorescence, and proximity ligation assay showed that p21 forms a complex with p-Chk2 under 5FU exposure. Using in silico computer modeling, we suggest that the p21/p-Chk2 interaction hindered the nuclear localization signal of p-Chk2, and therefore, the complex is exported out of the nucleus. These findings unravel a novel mechanism regarding an oncogenic role of p21 in regulation of resistance to 5FU-based chemotherapy. We suggest a possible value of cytoplasmic p21 as a prognosis marker and a therapeutic target in colorectal cancer patients.

MicroRNA expression profiles identify biomarkers for predicting the response to chemoradiotherapy in rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) following surgery significantly improves the survival rate of patients with rectal cancer. However, nCRT is associated with significant adverse symptoms and high medical costs. Therefore, it is important to investigate potential biomarkers for the prediction of the response to nCRT in patients with rectal cancer. The present study identified candidate biomarkers for predicting a complete response (CR) to nCRT in patients with rectal cancer and investigated the associated mechanisms. Microarray data (accession no. GSE29298) was downloaded from the Gene Expression Omnibus database. Differentially expressed microRNAs (miRNAs/miR) were screened between the pathological CR (pCR) group and no pCR (incomplete response) group. miRNA target genes were predicted using the miRWalk 2.0 online tool and subjected to Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Furthermore, a miRNA co‑regulatory network was constructed and disease‑associated genes were predicted. The results demonstrated that a total of 36 upregulated and 5 downregulated miRNAs were identified between the two groups. Among these differentially expressed miRNAs, miR‑548c‑5p, miR‑548d‑5p and miR‑663a were significantly associated with a CR to nCRT. The co‑regulatory network and pathway analysis indicated that miR‑548c‑5p and miR‑548d‑5p may function together through stem cell pluripotency and ubiquitin‑mediated proteolysis signaling pathways. Furthermore, the prediction of disease‑associated genes demonstrated that miR‑548c‑5p/miR‑548d‑5p and miR‑663a may regulate genes associated with rectal cancer, including mutated in colorectal cancers (MCC) and adenomatous polyposis coli (APC), and colorectal neoplasms, including interleukin‑6 signal transducer (IL6ST), cell cycle checkpoint kinase 2 (CHEK2), marker of proliferation Ki‑67 (MKI67), cadherin 7 (CDH7), calreticulin (CALR) and transforming growth factor β1 (TGFB1). Therefore, miR‑548c‑5p, miR‑548d‑5p and miR‑663a are promising candidate biomarkers for predicting a CR to nCRT. miR‑548c‑5p/miR‑548d‑5p may be associated with a CR by regulating IL6ST, CHEK2, MKI67 and MCC. In addition, it may function through the pluripotency of stem cells and ubiquitin‑mediated proteolysis signaling pathways. miR‑663a may be associated with a CR to nCRT by targeting CDH7, CALR, APC and TGFβ1. Thus, the miRNA biomarkers investigated in the present study may represent novel therapeutic targets for the prediction and eventual improvement of the response to nCRT in patients with rectal cancer.

p53 Mediates Vast Gene Expression Changes That Contribute to Poor Chemotherapeutic Response in a Mouse Model of Breast Cancer

p53 is a transcription factor that regulates expression of genes involved in cell cycle arrest, senescence, and apoptosis. TP53 harbors mutations that inactivate its transcriptional activity in roughly 30% of breast cancers, and these tumors are much more likely to undergo a pathological complete response to chemotherapy. Thus, the gene expression program activated by wild-type p53 contributes to a poor response. We used an in vivo genetic model system to comprehensively define the p53- and p21-dependent genes and pathways modulated in tumors following doxorubicin treatment. We identified genes differentially expressed in spontaneous mammary tumors harvested from treated MMTV-Wnt1 mice that respond poorly (Trp53+/+) or favorably (Trp53-null) and those that lack the critical senescence/arrest p53 target gene Cdkn1a. Trp53 wild-type tumors differentially expressed nearly 10-fold more genes than Trp53-null tumors after treatment. Pathway analyses showed that genes involved in cell cycle, senescence, and inflammation were enriched in treated Trp53 wild-type tumors; however, no genes/pathways were identified that adequately explain the superior cell death/tumor regression observed in Trp53-null tumors. Cdkn1a-null tumors that retained arrest capacity (responded poorly) and those that proliferated (responded well) after treatment had remarkably different gene regulation. For instance, Cdkn1a-null tumors that arrested upregulated Cdkn2a (p16), suggesting an alternative, p21-independent route to arrest. Live animal imaging of longitudinal gene expression of a senescence/inflammation gene reporter in Trp53+/+ tumors showed induction during and after chemotherapy treatment, while tumors were arrested, but expression rapidly diminished immediately upon relapse.

Non-Cell Autonomous Effects of the Senescence-Associated Secretory Phenotype in Cancer Therapy

In addition to promoting various forms of cell death, most conventional anti-tumor therapies also promote senescence. There is now extensive evidence that therapy-induced senescence (TIS) might be transient, raising the concern that TIS could represent an undesirable outcome of therapy by providing a mechanism for tumor dormancy and eventual disease recurrence. The senescence-associated secretory phenotype (SASP) is a hallmark of TIS and may contribute to aberrant effects of cancer therapy. Here, we propose that the SASP may also serve as a major driver of escape from senescence and the re-emergence of proliferating tumor cells, wherein factors secreted from the senescent cells contribute to the restoration of tumor growth in a non-cell autonomous fashion. Accordingly, anti-SASP therapies might serve to mitigate the deleterious outcomes of TIS. In addition to providing an overview of the putative actions of the SASP, we discuss recent efforts to identify and eliminate senescent tumor cells.

Predictors of Sensitivity to Preoperative Chemoradiotherapy of Rectal Adenocarcinoma

Objectives

The purpose of the study was to identify predictive factors of tumor response to preoperative chemoradiotherapy for rectal adenocarcinoma.

Methods

Ninety-eight patients with nonmetastatic rectal adenocarcinoma received preoperative concurrent chemoradiotherapy and underwent mesorectal excision. After treatment, tumor response according to tumor regression grade were evaluated. The correlation of clinicopathologic factors to tumor response was analyzed.

Results

The results from a univariate analysis indicated that pretreatment carcinoembryonic antigen level ≤3.0 ng/ml (P = 0.002), non-fixed tumor (P = 0.001), and tumor circumferential extent ≤50% (P = 0.001) were associated significantly with a good tumor response. They also indicated that pretreatment positive lymph nodes (P = 0.032) were associated significantly with a poor tumor response. In multivariate analysis, the results indicated that pretreatment carcinoembryonic antigen level (hazard ratio, 2.930; P = 0.003), tumor mobility (hazard ratio, 2.651; P = 0.002) and circumferential extent of tumor (hazard ratio, 2.394; P = 0.019) independently predicted a good pathologic response rate. Pretreatment positive lymph nodes were not significantly associated with a good response (hazard ratio, 0.361; P = 0.191).

Conclusions

Pretreatment carcinoembryonic antigen level, tumor mobility and circumferential extent of tumor may be helpful in predicting responsiveness in rectal adenocarcinoma to preoperative chemoradiotherapy, although the results should be confirmed in larger, more homogeneous studies.

SASP: Tumor Suppressor or Promoter? Yes!

Cellular senescence is a permanent growth arrest in cells with damage or stress that could lead to transformation. Some tumor cells also undergo senescence in response to chemotherapy. Senescent cells secrete cytokines and other factors of the senescence-associated secretory phenotype (SASP) that contribute to tumor suppression by enforcing arrest and recruiting immune cells that remove these damaged or oncogene-expressing cells from organisms. However, some cells can develop a SASP comprising factors that are immunosuppressive and protumorigenic by paracrine mechanisms. Likewise, the SASP in treated cancers can either contribute to durable responses or drive relapse. Here, we discuss the studies that have demonstrated a complex and often conflicting role for the SASP in tumorigenesis and treatment response.

CGK733-induced LC3 II formation is positively associated with the expression of cyclin-dependent kinase inhibitor p21Waf1/Cip1 through modulation of the AMPK and PERK/CHOP signaling pathways

Microtubule-associated protein 1A/1B-light chain 3 (LC3)-II is essential for autophagosome formation and is widely used to monitor autophagic activity. We show that CGK733 induces LC3 II and LC3-puncta accumulation, which are not involved in the activation of autophagy. The treatment of CGK733 did not alter the autophagic flux and was unrelated to p62 degradation. Treatment with CGK733 activated the AMP-activated protein kinase (AMPK) and protein kinase RNA-like endoplasmic reticulum kinase/CCAAT-enhancer-binding protein homologous protein (PERK/CHOP) pathways and elevated the expression of p21Waf1/Cip1. Inhibition of both AMPK and PERK/CHOP pathways by siRNA or chemical inhibitor could block CGK733-induced p21Waf1/Cip1 expression as well as caspase-3 cleavage. Knockdown of LC3 B (but not LC3 A) abolished CGK733-triggered LC3 II accumulation and consequently diminished AMPK and PERK/CHOP activity as well as p21Waf1/Cip1 expression. Our results demonstrate that CGK733-triggered LC3 II formation is an initial event upstream of the AMPK and PERK/CHOP pathways, both of which control p21Waf1/Cip1 expression.

New Perspectives on Predictive Biomarkers of Tumor Response and Their Clinical Application in Preoperative Chemoradiation Therapy for Rectal Cancer

Preoperative chemoradiation therapy (CRT) is the standard treatment for patients with locally advanced rectal cancer (LARC) and can improve local control and survival outcomes. However, the responses of individual tumors to CRT are not uniform and vary widely, from complete response to disease progression. Patients with resistant tumors can be exposed to irradiation and chemotherapy that are both expensive and at times toxic without benefit. In contrast, about 60% of tumors show tumor regression and T and N down-staging. Furthermore, a pathologic complete response (pCR), which is characterized by sterilization of all tumor cells, leads to an excellent prognosis and is observed in approximately 10-30% of cases. This variety in tumor response has lead to an increased need to develop a model predictive of responses to CRT in order to identify patients who will benefit from this multimodal treatment. Endoscopy, magnetic resonance imaging, positron emission tomography, serum carcinoembryonic antigen, and molecular biomarkers analyzed using immunohistochemistry and gene expression profiling are the most commonly used predictive models in preoperative CRT. Such modalities guide clinicians in choosing the best possible treatment options and the extent of surgery for each individual patient. However, there are still controversies regarding study outcomes, and a nomogram of combined models of future trends is needed to better predict patient response. The aim of this article was to review currently available tools for predicting tumor response after preoperative CRT in rectal cancer and to explore their applicability in clinical practice for tailored treatment.

The prognostic significance of tumor epidermal growth factor receptor (EGFR) expression change after neoadjuvant chemoradiation in patients with rectal adenocarcinoma

Aim of the study

The aim of this retrospective study was to determine the prognostic impact of epidermal growth factor receptor (EGFR) expression changes during neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer.

Material and methods

Fifty patients with locally advanced rectal cancer were evaluated. All the patients were administered the total dose of 44 Gy. Capecitabine has been concomitantly administered in the dose 825 mg/m² in two daily oral administrations. Surgery was indicated 4–8 weeks from the chemoradiotherapy completion. Epidermal growth factor receptor expression in the pretreatment biopsies and in the resected specimens was assessed with immunohistochemistry.

Results

All of 50 patients received radiotherapy without interruption up to the total planned dose. In 30 patients sphincter-saving surgery was performed, 20 patients underwent amputation of the rectum. Downstaging was described in 30 patients. Four patients have had complete pathologic remission. Twenty-six patients have had partial remission, the disease was stable in 15 patients. Progression was reported in 5 patients. The median disease-free survival was 64.9 months, median overall survival was 76.4 months. Increased EGFR expression was found in 12 patients (26.1%). A statistically significantly shorter overall survival (p < 0.0001) and disease-free survival (p < 0.0001) was found in patients with increased expression of EGFR compared with patients where no increase in the expression of EGFR during neoadjuvant chemoradiotherapy was observed.

Conclusions

The overexpression of EGFR during neoadjuvant chemoradiotherapy for locally advanced rectal adenokarcinoma associated with significant shorter overall survival and disease free survival.

Prediction of response to preoperative chemoradiotherapy in patients with locally advanced rectal cancer

Preoperative chemoradiotherapy (CRT) combined with surgery has become a standard treatment strategy for patients with locally advanced rectal cancer (LARC). The pathological response is an important prognostic factor for LARC. The variety of tumor responses has increased the need to find a useful predictive model for the response to CRT to identify patients who will really benefit from this multimodal treatment. Magnetic resonance imaging (MRI), positron emission tomography-computed tomography (PET-CT), serum carcinoembryogenic antigen (CEA), molecular biomarkers analyzed by immunohistochemistry and gene expression profiling are the most used predictive models in LARC. The majority of predictors have yielded encouraging results, but there is still controversy. Diffusion-weighted MRI may be the best model to detect the dynamic changes of rectal cancer and predict the response at an early stage. Gene expression profiling and single nucleotide polymorphisms hold considerable promise to unveil the underlying complex genetics of response to CRT. Because each parameter has its own inherent shortcomings, combined models may be the future trend to predict the response.

Can a biomarker-based scoring system predict pathologic complete response after preoperative chemoradiotherapy for rectal cancer?

BACKGROUND

Numerous molecular markers have been investigated as potential predictors of tumor responses to preoperative chemoradiotherapy (preCRT) for rectal cancer.

OBJECTIVE

To develop a system in which biomarkers are used to predict the likelihood of a pathologic complete response (pCR) to preCRT.

DESIGN & SETTING

This is a retrospective analysis of tumor specimens collected prior to preCRT from 81 patients who underwent curative resection for primary rectal adenocarcinoma between June 2008 and February 2012.

MAIN OUTCOME MEASURES

Using tissue microarrays and immunohistochemistry, expression levels of twelve candidate biomarkers (p53, p21, Bcl2, Bax, EGFR, Cox-2, MLH-1, MSH-2, Ku70, VEGF, TS, Ki-67) were evaluated in paraffin-embedded tumor samples collected before preCRT. The correlation between biomarker expression levels and the pathologic response to preCRT was assessed based on histopathological staging (pTNM) and tumor regression grade (TRG).

RESULTS

Expression levels of 4 biomarkers (p53, VEGF, p21, Ki67) correlated with pCR. Patients showing low expression of p53 and/or high expression of VEGF, p21, and Ki67 exhibited a significantly greater pCR rate. A scoring system devised so that one point was given for each biomarker whose expression level correlated with pCR (score range: 0-4) showed that 1 of 26 patients with scores of 0 to 1 achieved pCR, whereas 26 of 55 patients with scores of 2 to 4 achieved pCR (3.8% vs. 47.3%, p < 0.001). For prediction of pCR, the scoring system showed 96.3% sensitivity, 46.3% specificity, a 47.3% positive predictive value, and a 96.2% negative predictive value.

LIMITATIONS

Immunohistochemistry has limitations related to reproducibility and the ability to provide quantitative information. In addition, this study lacks test and validation sets.

CONCLUSIONS

Expression levels of 4 biomarkers correlated with pCR after preCRT for rectal cancer. A scoring system based on levels of biomarker expression showed good sensitivity and negative predictive value for pCR.

p27 expression in post-treatment rectal cancer: a potential novel approach for predicting residual nodal disease

BACKGROUND

Expression profiles of p21, p27, p53, Ki-67, and thymidylate synthase may be associated with response to neoadjuvant chemoradiation. The relationship between post-treatment protein expression and regional lymph node involvement has not been fully explored.

METHODS

Tumor cores from 126 rectal cancer patients underwent immunohistochemical analysis for the aforementioned proteins. Staining indices (SIs) using percentage of stained cells and staining intensity were calculated for 10 tumor cores per patient. SI for each marker was compared between node negative and node positive patients.

RESULTS

Twenty-six (20.6%) cancer patients had a pathologic complete response and 37 had inadequate tissue or cancer cells, leaving 63 for analysis. Thirty-seven (58.7%) cancer patients were node negative and 26 (41.3%) were node positive. There was an association between increased p27 SI and nodal positivity (P = .04).

CONCLUSION

Increased p27 expression in post-treatment rectal cancer is associated with nodal positivity and may determine which patients are suitable for local excision.

P21 and CD166 as predictive markers of poor response and outcome after fluorouracil-based chemoradiotherapy for the patients with rectal cancer

Background

Pre-operative chemoradiotherapy (CRT) is the standard treatment in clinical stage T3/4 or node positive rectal cancer. However, there are no established biomarkers that can predict the pathological response and clinical outcome to CRT.

Methods

Immunohistochemical staining was performed in tissue arrays constructed from core tissue specimens taken before treatment and from operative specimens from 112 patients who received 5-FU based pre-operative CRT and surgery. Expression of Ki67, TS, BAX, EpCAM, p53, p21, EGFR, CD44, CD133, CD166, HIF1α and ALDH1 were assessed and correlated with tumor regression grades and disease free survival.

Results

Of the 112 patients (M/F 74/38, median age: 62), 20 (17.9%) patients achieved pathologic complete remission (pCR). In analyzing the associations between marker expressions and tumor regression grades, high p21 expression at the pretreatment biopsy was significantly associated with non-pCR (p = 0.022) and poor disease free survival (median DFS - low vs high p21: 75.8 vs 58.1 months, p = 0.002). In the multivariate analysis, high p21 expression level at the pre-treatment biopsy was significantly associated with poor DFS (p = 0.001, HR 6.14; 95% CI 2.03, 18.55). High CD166 expression level at the pretreatment biopsy was also associated with poor DFS (p = 0.003; HR 5.61; 95% CI 1.81, 17.35).

Conclusion

These show high p21 and CD166 expression at the pretreatment biopsy were associated with tumor regression and poor prognosis in patients treated with 5-FU based CRT. Larger, prospective and functional studies are warranted to determine the role of p21 and CD166 as predictive biomarker of response to CRT.

Small double-stranded RNA mediates the anti-cancer effects of p21WAF1/ClP1 transcriptional activation in a human glioma cell line

PURPOSE

This study was conducted to investigate the small double-stranded RNA (dsRNA) mediated anti-tumor effects of p21WAF1/ClP1 (p21) transcriptional activation in vitro in the human glioma SHG-44 cell line.

MATERIALS AND METHODS

Human glioma SHG-44 cells were transfected with dsRNA using LipofectAMINE 2000 transfection reagent. Real-time PCR and Western blot analysis were conducted to detect p21 and survivin mRNA and protein levels, respectively. Cell proliferation was examined by MTT assay. Cell cycle distribution and apoptosis were detected by flow-cytometric analysis.

RESULTS

We found that dsRNA targeting p21 promoter (dsP21) significantly induced the expression of p21 at transcription and protein levels, and reduced the expression of survivin. AS well, dsP21 transcription significantly inhibited human glioma SHG-44 cell proliferation. Analysis of cell cycle distribution revealed that dsP21 transfection increased accumulation of cells in the G0/G1 phase and reduced accumulation of cells in the S phase. Further analysis revealed that dsP21 transcription led to an increase in both early and late stages of apoptosis in human glioma SHG-44 cells.

CONCLUSION

In the present study, P21 activation by RNA-induced gene activation (RNAa) induced anti-tumor activity in vitro in a human glioma SHG-44 cell line. The results suggested that RNAa could be used for human glioma treatment by targeted activation of tumor suppressor genes.

p14ARF induces apoptosis via an entirely caspase-3-dependent mitochondrial amplification loop

The p14(ARF) tumor suppressor triggers cell death or cell cycle arrest upon oncogenic stress. In MCF-7 breast carcinoma cells, expression of the tumor suppressor gene p14(ARF) fails to trigger apoptosis but induces an arrest in the G1 and, to a lesser extent, in the G2 phase in the cell division cycle. Here, inhibition of cell cycle arrest resulted in apoptosis induction in caspase-3 proficient MCF-7 cells upon expression of p14(ARF) . This occurred in the absence of S-phase progression or mitotic entry. In contrast, syngeneic, caspase-3-deficient MCF-7 cells remained entirely resistant to p14(ARF) -induced apoptosis. Thus, cell cycle checkpoint abrogation overcomes resistance to p14(ARF) -induced cell death and promotes cell death via a caspase-3-dependent pathway. Cell death coincided with dissipation of the mitochondrial membrane potential, release of cytochrome c, and was inhibitable by pan-caspase inhibitors and the caspase-3/7 inhibitor zDEVD-fmk. Of note, mitochondrial events of apoptosis execution depended entirely on caspase-3 proficiency indicating that caspase-3 either acts "up-stream" of the mitochondria in a "non-canonical" pathway or mediates a mitochondrial feedback loop to amplify the apoptotic caspase signal in p14(ARF) -induced stress signaling.

The prognostic value of the apoptosis pathway in colorectal cancer: a review of the literature on biomarkers identified by immunohistochemistry

Research towards biomarkers that predict patient outcome in colorectal cancer (CRC) is rapidly expanding. However, none of these biomarkers have been recommended by the American Association of Clinical Oncology or the European Group on Tumor Markers. Current staging criteria result in substantial under-and over-treatment of CRC patients. Evasion of apoptosis, a characteristic feature of tumorigenesis, is known to correlate with patient outcome. We reviewed the literature on immunohistochemistry-based studies between 1998 and 2011 describing biomarkers in this pathway in CRC and identified 26 markers. Most frequently described were p53, Bcl-2, survivin, and the Fas and TRAILR1 receptors and their ligands. None of the studies reviewed provided sufficient support for implementing a single marker into current clinical practice. This is likely due to the complex biology of this pathway. We suggest focusing on the combination of key markers within the apoptosis pathway that together represent an ‘apoptotic tumor profile’, which better reflects the status of this pathway in a tumor.

The mitochondrial transport protein SLC25A43 affects drug efficacy and drug-induced cell cycle arrest in breast cancer cell lines

The mitochondria have been identified as key players of apoptosis, cell proliferation and cell cycle regulation. However, the role of mitochondria in breast cancer and treatment failure remains unclear. We have previously shown a common deletion of the gene SLC25A43 in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. This gene is coding for a mitochondrial inner membrane transporter and, to date, little is known about the function of this protein. We have also found that low protein expression of SLC25A43 significantly correlates with a lower S phase fraction in HER2-positive breast cancer. The aim of this study was to investigate whether knockdown (KD) of SLC25A43 could have an effect on the cytotoxicity of different cytostatic drugs using MCF10A, MCF7 and BT-474 cells. Following siRNA-mediated KD of SLC25A43, one non-malignant and two breast cancer cell lines were exposed to the anthracycline epirubicin or the taxane paclitaxel. The HER2-positive breast cancer cells were also exposed to the targeted therapy trastuzumab and dual exposure to trastuzumab and paclitaxel. We found that KD of SLC25A43 resulted in a decreased cytotoxic effect of paclitaxel in the two cancer cell lines (P<0.05). Further analysis of cell cycle phase distribution showed that KD increased the paclitaxel-induced G2/M block in these two cell lines (P<0.05). KD of SLC25A43 also reduced the inhibitory effect of trastuzumab on cell proliferation in the HER2-positive cancer cell line BT-474 (P<0.05), and the drug-induced G0/G1 block (P<0.05). Moreover, SLC25A43 influenced the percentage of Ki-67-positive cells. Our findings demonstrate that the mitochondrial protein SLC25A43 affects drug efficacy and cell cycle regulation following drug exposure in breast cancer cell lines.

Low Mmp 9 and VEGF levels predict good oncologic outcome in mid and low rectal cancer patients with neoadjuvant chemoradiation

Background

The aim of this study was to evaluate apoptotic (Bcl-2, Bax expression, caspase-3 activity, and cytochrome-c) and angiogenic (MMP-9 levels and VEGF expression) markers in operable rectal cancer patients who were treated with preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME). Understanding these factors will facilitate the identification of potential pathological responders before treatment, leading to better local control and survival rates.

Methods

Between March 2006 and March 2008, 29 patients withTNM Stage III (cT3 N+) mid or low rectal cancer were included in this study. Our sample consisted of 17 males (58.6%) and 12 females (41.4%). The median age was 60 years (range 24-88 years). Biopsy samples were taken from different portions of the tumors using flexible endoscopy before neoadjuvant CRT. Preoperatively, all patients received radiation (45-50.4 gray (Gy) in 25 cycles with concurrent 5-florouracil (5-FU) chemotherapy.

Results

A complete response was observed in 7 of 29 patients (24%). Bax staining was negative in 1 of the 7 patients (14%) in the pathological complete response (PCR) group and in 18 of the 22 patients (82%) in the no pathological complete response (noPCR) group (p = 0.001). MMP-9 and VEGF levels were higher in the noPCR group than the PCR group (p = 0.04, p = 0.05 respectively). No statistically significant differences were found between VEGF and MMP-9 levels in nodal downstaging. No statistically significant relationships were found between the other apoptotic factors (Bcl 2, cytochrome-c, and caspase-3 activity) and pathological response rate (p > 0.05).

Conclusion

In neoadjuvant CRT patients, high levels of Bax expression and low levels of VEGF and MMP-9 expression on preoperative biopsies indicate that the patient will potentially be a good pathological responder.

On biomarkers and pathways in rectal cancer: What's the target?

In spite of tremendous progresses in surgical and chemo-radiotherapeutic regimens, rectal cancer still suffers from high relapse and mortality rates, and metastatic disease is incurable. Here we assess some of the most recent and validated biomarkers and potential targets studied in rectal cancer, and provide comments to a recent monographic topic covering several aspects of colorectal cancer, published in Current Cancer Drug Targets.

Immunohistological expression of HIF-1α, GLUT-1, Bcl-2 and Ki-67 in consecutive biopsies during chemoradiotherapy in patients with rectal cancer

The aim of this study was to describe the dynamics of HIF-1α, GLUT-1, Bcl-2 and Ki-67 during chemoradiotherapy (CRT) of rectal cancer, and to investigate the fluctuation of these biomarkers in relation to pathological response to CRT. The study included 86 patients with rectal adenocarcinoma receiving preoperative CRT (>50.4 Gy and Uracil/Tegafur). Immunohistological expressions of HIF-1α, GLUT-1, Bcl-2 and Ki-67 were investigated in biopsies taken before treatment, after 2, 4 and 6 weeks of CRT and in specimens from the operation. Decreasing expressions of HIF-1α, Bcl-2 and Ki-67 were observed during CRT, whereas GLUT-1 overall was unchanged. No significant changes of the markers were observed in the interval between CRT and surgery. A significant association was observed between the presence of residual carcinoma after 6 weeks of treatment and pathological response to CRT, but no association was seen between the fluctuations of any of the markers and response to CRT. This unique material containing specimens before, after and during CRT for rectal cancer demonstrated biological dynamics in HIF-1α, Bcl-2 and Ki-67, but not GLUT-1, expression during CRT, and a significant association was seen between the presence of residual carcinoma after 6 weeks of treatment and pathological response to CRT.

Effects of activin and TGFβ on p21 in colon cancer

Activin and TGFβ share SMAD signaling and colon cancers can inactivate either pathway alone or simultaneously. The differential effects of activin and TGFβ signaling in colon cancer have not been previously dissected. A key downstream target of TGFβ signaling is the cdk2 inhibitor p21 (p21^cip1/waf1). Here, we evaluate activin-specific effects on p21 regulation and resulting functions. We find that TGFβ is a more potent inducer of growth suppression, while activin is a more potent inducer of apoptosis. Further, growth suppression and apoptosis by both ligands are dependent on SMAD4. However, activin downregulates p21 protein in a SMAD4-independent fashion in conjunction with increased ubiquitination and proteasomal degradation to enhance migration, while TGFβ upregulates p21 in a SMAD4-dependent fashion to affect growth arrest. Activin-induced growth suppression and cell death are dependent on p21, while activin-induced migration is counteracted by p21. Further, primary colon cancers show differential p21 expression consistent with their ACVR2/TGFBR2 receptor status. In summary, we report p21 as a differentially affected activin/TGFβ target and mediator of ligand-specific functions in colon cancer, which may be exploited for future risk stratification and therapeutic intervention.

Predicting the response to preoperative radiation or chemoradiation by a microarray analysis of the gene expression profiles in rectal cancer

Preoperative radiotherapy or chemoradiotherapy (CRT) has become a standard treatment for patients with locally advanced rectal cancer. However, there is a wide spectrum of responses to preoperative CRT, ranging from none to complete. There has been intense interest in the identification of molecular biomarkers to predict the response to preoperative CRT, in order to spare potentially non-responsive patients from unnecessary treatment. However, no specific molecular biomarkers have yet been definitively proven to be predictive of the response to CRT. Instead of focusing on specific factors, microarray-based gene expression profiling technology enables the simultaneous analysis of large numbers of genes, and might therefore have immense potential for predicting the response to preoperative CRT. We herein review published studies using a microarray-based analysis to identify gene expression profiles associated with the response of rectal cancer to radiation or CRT. Although some studies have reported gene expression signatures capable of high predictive accuracy, the compositions of these signatures have differed considerably, with little gene overlap. However, considering the promising data regarding gene profiling in breast cancer, the microarray analysis could still have potential to improve the management of locally advanced rectal cancer. Increasing the number of patients analyzed for more accurate prediction and the extensive validation of predictive classifiers in prospective clinical trials are necessary before such profiling can be incorporated into future clinical practice.

ID1 and ID3 regulate the self-renewal capacity of human colon cancer-initiating cells through p21

There is increasing evidence that some cancers are hierarchically organized, sustained by a relatively rare population of cancer-initiating cells (C-ICs). Although the capacity to initiate tumors upon serial transplantation is a hallmark of all C-ICs, little is known about the genes that control this process. Here, we establish that ID1 and ID3 function together to govern colon cancer-initiating cell (CC-IC) self-renewal through cell-cycle restriction driven by the cell-cycle inhibitor p21. Regulation of p21 by ID1 and ID3 is a central mechanism preventing the accumulation of excess DNA damage and subsequent functional exhaustion of CC-ICs. Additionally, silencing of ID1 and ID3 increases sensitivity of CC-ICs to the chemotherapeutic agent oxaliplatin, linking tumor initiation function with chemotherapy resistance.

Combination of differentiation and T stage can predict unresponsiveness to neoadjuvant therapy for rectal cancer

AIM

The study aimed to identify the factors predictive for extreme unresponsiveness to neoadjuvant therapy for rectal cancer.

METHOD

Ninety-six patients with rectal cancer received neoadjuvant therapy (41 were treated with radiotherapy and 55 with chemoradiotherapy) before surgery. Tumour response, downstaging, pathological complete response (pCR) and disease-free survival were evaluated.

RESULTS

Tumour response, downstaging and pCR occurred in 70 (72.9%), 47 (49.0%) and 14 (14.6%) patients, respectively. Univariate analyses showed that a large tumour size, T4 stage, elevated serum tumour markers, poor differentiation, radiotherapy alone and mucinous tumour were indicators of poor tumour response and/or downstaging. On multivariate analysis, chemoradiotherapy was found to be predictive for tumour response and downstaging, whereas mucinous type and T4 stage negatively affected tumour response. No variable was found to be associated with pCR, but poor differentiation and T4 stage together predicted extreme unresponsiveness with a high specificity and a high positive predictive value. Very poor disease-free survival was also observed in patients simultaneously carrying these phenotypes.

CONCLUSION

Neoadjuvant chemoradiotherapy is superior to radiotherapy alone in producing a response of rectal cancer. Unresponsiveness was most likely to occur in patients with poor differentiation and T4 disease.

Identification of a biomarker profile associated with resistance to neoadjuvant chemoradiation therapy in rectal cancer

OBJECTIVE

To identify a biomarker profile associated with tumor response to chemoradiation (CRT) in locally advanced rectal cancer.

BACKGROUND

Rectal cancer response to neoadjuvant CRT is variable. Whereas some patients have a minimal response, others achieve a pathologic complete response (pCR) and have no viable cancer cells in their surgical specimens. Identifying biomarkers of response will help select patients more likely to benefit from CRT.

METHODS

This study includes 132 patients with locally advanced rectal cancer treated with neoadjuvant CRT followed by surgery. Tumor DNA from pretreatment tumor biopsies and control DNA from paired normal surgical specimens was screened for mutations and polymorphisms in 23 genes. Genetic biomarkers were correlated with tumor response to CRT (pCR vs non-pCR), and the association of single or combined biomarkers with tumor response was determined.

RESULTS

Thirty-three of 132 (25%) patients achieved a pCR and 99 (75%) patients had non-pCR. Three individual markers were associated with non-pCR; v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutation (P = 0.0145), cyclin D1 G870A (AA) polymorphism (P = 0.0138), and methylenetetrahydrofolate reductase (NAD(P)H) C677T (TT) polymorphism (P = 0.0120). Analysis of biomarker combinations revealed that none of the 27 patients with both tumor protein p53 (p53) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations had a pCR. Further, in patients with both p53 and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations or the cyclin D1 G870A (AA) polymorphism or the methylenetetrahydrofolate reductase (NAD(P)H) C677T (TT) polymorphism (n = 52) the association with non-pCR was further strengthened; 51 of 52 (98%) of patients were non-pCR. These biomarker combinations had a validity of more than 70% and a positive predictive value of 97% to 100%, predicting that patients harboring these mutation/polymorphism profiles will not achieve a pCR.

CONCLUSIONS

A specific biomarker profile is strongly associated with non-pCR to CRT and could be used to select optimal oncologic therapy in rectal cancer patients. ClinicalTrials.org Identifier: NCT00335816.

TS and ERCC-1 mRNA expressions and clinical outcome in patients with metastatic colon cancer in CONFIRM-1 and -2 clinical trials

To validate established cutoff levels of thymidylate synthase (TS) and excision repair cross-complementing (ERCC-1) intratumoral mRNA expressions in tumor samples from metastatic colorectal cancer (mCRC) patients treated with PTK787/ZK222584 (PTK/ZK). From 122 samples of patients with mCRC enrolled in CONFIRM-1 (Colorectal Oral Novel Therapy for the Inhibition of Angiogenesis and Retarding of Metastases) or CONFIRM-2, mRNA was isolated of microdissected formalin-fixed paraffin-embedded samples and quantitated using TaqMan-based technology. Existing TS and ERCC-1 cutoff levels were tested for their prognostic value in first-line and second-line therapy. TS expression was associated with overall survival (OS) in first-line, but not second-line therapy. ERCC-1 was associated with OS in patients treated with first-line and second-line FOLFOX4. In first-line FOLFOX4, combination of high TS and/or high ERCC-1 was associated with shorter OS. A correlation was observed between ERCC-1 expression and benefit from PTK/ZK+FOLFOX4 treatment. TS and ERCC-1 expression is associated with clinical outcome in mCRC. Baseline TS and ERCC-1 levels may allow the selection of patients who benefit from FOLFOX4 chemotherapy.

Predictive factors of pathologic complete response after neoadjuvant chemoradiation for rectal cancer

OBJECTIVE

This study evaluates factors associated with a pathologic complete response (pCR) after neoadjuvant chemoradiation for rectal cancer.

SUMMARY BACKGROUND DATA

Approximately 20% of rectal cancer patients undergoing neoadjuvant chemoradiation achieve pCR, which has been associated with decreased local recurrence and improved recurrence-free survival. Means of predicting pCR remain incompletely defined.

METHODS

A total of 306 consecutive patients with stage II or stage III rectal cancer who underwent neoadjuvant chemoradiation then surgery between 1997 and 2007 were identified from a single-institution. Sixty-four patients with concurrent inflammatory bowel disease, hereditary colorectal cancer, other malignancy, urgent surgery, incomplete chemoradiation, or insufficient data were excluded. All patients received neoadjuvant 5-FU-based chemotherapy and external beam radiation. Histologic response was categorized as pCR or not-pCR, which defined the 2 study cohorts. Variables were analyzed by univariate and multivariate analysis with pCR as the dependent variable. Fisher exact test, chi2, Wilcoxon rank-sum, and logistic regression were used for analysis. P < 0.05 was considered statistically significant.

RESULTS

Of the total patients, 242 were studied, including 58 (24%) that achieved pCR. The 2 groups were statistically similar in terms of age, gender, body mass index, tumor differentiation, radiation dose, and pretreatment stage. On multivariate analysis, an interval ≥ 8 weeks between treatment completion and surgical resection was significantly associated with a higher rate of pCR, which correlated with decreased local recurrence and improved overall survival.

CONCLUSION

Despite traditional beliefs that certain patient and tumor factors influence pCR, an extended interval between completion of neoadjuvant therapy and surgery was the single most important determinant in achieving a pCR.

The Prognostic Impact of p53 Expression on Sporadic Colorectal Cancer Is Dependent on p21 Status

The prognostic value of p53 and p21 expression in colorectal cancer is still under debate. We hypothesize that the prognostic impact of p53 expression is dependent on p21 status. The expression of p53 and p21 was immunohistochemically investigated in a prospective cohort of 116 patients with UICC stage II and III sporadic colorectal cancer. The results were correlated with overall and recurrence-free survival. The mean observation period was 51.8 ± 2.5 months. Expression of p53 was observed in 72 tumors (63%). Overall survival was significantly better in patients with p53-positive carcinomas than in those without p53 expression (p = 0.048). No differences were found in recurrence-free survival (p = 0.161). The p53+/p21− combination was seen in 68% (n = 49), the p53+/p21+ combination in 32% (n = 23). Patients with p53+/p21− carcinomas had significantly better overall and recurrence-free survival than those with p53+/p21+ (p < 0.0001 resp. p = 0.003). Our data suggest that the prognostic impact of p53 expression on sporadic colorectal cancer is dependent on p21 status.

Expression of p21WAF1 in Astler-Coller stage B2 colorectal cancer is associated with survival benefit from 5FU-based adjuvant chemotherapy

In several, but not all, previous studies, positive p21^WAF1 expression has been suggested as an indicator of a good prognosis in patients with stage III/IV colorectal cancer. However, it is not known whether the same is true for stage B2 patients. The purpose of this study is to assess the influence of p21^WAF1 expression in tumor cells on disease-free survival (DFS) and overall survival (OS) of Astler–Coller stage B2 and C patients with colorectal cancer who underwent 5-fluorouracil-based adjuvant chemotherapy. Nuclear p21^WAF1 was detected by immunohistochemistry in tissue microarrays from 275 colorectal cancers. The expression of p21^WAF1 was associated with DFS (p = 0.025) and OS (p = 0.008) in the subgroup of stage B2 patients that was treated with adjuvant chemotherapy. In multivariate analysis, it remained the only independent prognostic parameter in relation to DFS and OS (p = 0.035 and p = 0.02, respectively). In the subgroup of 72 stage B2 patients with positive p21^WAF1 expression but not in the subgroup of 61 stage B2 patients with negative p21^WAF1 expression, adjuvant chemotherapy was associated with better DFS (85% 5-year survival versus 65% without chemotherapy, p = 0.03) and OS (96% versus 82%, p = 0.014). In the combined stage B2 and C group of patients treated with adjuvant chemotherapy, positive p21^WAF1 expression was also associated with better DFS and OS (p = 0.03, p = 0.002, respectively). Expression of p21^WAF1 in colorectal tumor cells identifies a subgroup of Astler–Coller stage B2 patients who could benefit significantly from 5FU-based chemotherapy and may improve the selection of patients for adjuvant chemotherapy.

Reduced p21(WAF1/CIP1) via alteration of p53-DDX3 pathway is associated with poor relapse-free survival in early-stage human papillomavirus-associated lung cancer

PURPOSE

DDX3 alteration has been shown to participate in hepatocellular tumorigenesis via p21(WAF1/CIP1) (p21) deregulation. We observed that DDX3 and p21 expression in lung tumors was negatively associated with E6 expression. Therefore, the aim of this study was to clarify whether deregulation of p21 by DDX3 via an E6-inactivated p53 pathway would enhance tumor progression in HPV-associated lung cancers.

EXPERIMENTAL DESIGN

Real-time PCR, luciferase assays, immunoprecipitation, and chromatin immunoprecipitation (ChIP) were performed to determine whether DDX3 was regulated by p53 to synergistically enhance p21 transcriptional activity. Cell proliferation was examined by cell counting and colony formation assays. DDX3 and p21 expression were evaluated in 138 lung tumors by real-time PCR and immunohistochemistry. The prognostic value of p21 expression on relapse-free survival (RFS) was analyzed by Kaplan-Meier analysis.

RESULTS

Real-time PCR, luciferase assays, and ChIP assays indicated that three putative p53 binding sites, located at -1,080/-1,070, -695/-685, and -283/-273 on the DDX3 promoter, were required for DDX3 transcription. DDX3 deregulation by the E6-inactivated p53 pathway could promote cell proliferation and the ability to form colonies via reduced Sp1 binding activity on the p21 promoter. Among tumors, p21 expression was positively associated with DDX3 expression and negatively related with E6 expression, particularly in early-stage (I + II) tumors. Interestingly, low p21 expression was associated with a poor RFS in early-stage lung cancer.

CONCLUSION

The reduction of p21 by the alteration of the p53-DDX3 pathway plays an essential role in early-stage HPV-associated lung tumorigenesis and is correlated with poor RFS of lung cancer patients.

Adjuvant therapy for T3N0 rectal cancer in the total mesorectal excision era- identification of the high risk patients

BACKGROUND

Adjuvant therapy for T3N0 rectal cancer was controversial with respect to both radiation and the use of a combined regimen of chemotherapy. We evaluated both clinical features and biomarkers and sought to determine risk factors for those patients retrospectively.

METHODS

A total of 122 patients with T3N0 rectal cancer were analyzed in this study from January 2000 to December 2005. Clinicopathologic and biomarkers were used to predict local recurrence (LR), disease-free survival (DFS), and overall survival (OS).

RESULTS

The median follow-up interval was 45.4 months. Five-year LR, DFS, and OS rates were 10.4%, 68.3%, and 88.7%. Having a lower tumor location and showing low P21 and high CD44v6 expression were identified as risk factors for LR: patients with two or three of these risk factors had a higher 5-year LR rate (19.3%) than did patients with none or one of these risk factors (6.8%) (p = 0.05). A poorer DFS was related to low P21 nor high CD44v6 expression but not to tumor location: the 5-year DFS rates were 79.3% for those with neither, 65.9% for those with either one or the other, and 16.9% for those with both (p = 0.00).

CONCLUSIONS

The prognostic model including tumor location, P21 and CD44v6 expressions could help to distinguish these patients with high risk T3N0 patients and determine whether adjuvant therapy was beneficial.

XRCC1 gene polymorphism for prediction of response and prognosis in the multimodality therapy of patients with locally advanced rectal cancer

BACKGROUND

Neoadjuvant treatment strategies have been developed to improve survival of patients with locally advanced rectal cancer. Since mainly patients with major histopathologic response benefit from this therapy, predictive markers are needed. The gene polymorphism of the X-ray-repair-cross complementing (XRCC1-) gene (rs25487) was analyzed to predict response to neoadjuvant radiochemotherapy and prognosis in patients with locally advanced rectal cancer.

PATIENTS AND METHODS

81 patients (51 male; 30 female; median age 59 years) with locally advanced rectal cancer were included in this study. All patients received a neoadjuvant radiochemotherapy (50.4 Gy, 5-FU) followed by surgical therapy. Histomorphologic regression was defined as major response when resected specimens contained less than 10% viable tumor cells (n = 28) and minor response when more than 10% viable tumor cells (n = 53) were detected in the surgical specimen. Genomic DNA was extracted from paraffin-embedded tissues of all study patients. Allelic discrimination was performed by real-time polymerase chain reaction. Two allele-specific TaqMan probes in competition were used for amplification of the XRCC1 gene. Allelic genotyping was correlated with therapy response and prognosis.

RESULTS

Single-nucleotide polymorphism XRCC1 A399G (rs25487) was predictive for therapy response (P = 0.039). Within the AG genotype group, 17 (53%) patients showed a minor response and 15 (47%) patients a major response. In contrast, 39 (78%) of the patients with homogeneous AA or GG genotype were minor responders and only 11 (22%) major responders. No prognostic value was revealed for the XRCC1 A399G (rs25487) gene polymorphism in the multimodality therapy.

CONCLUSION

Our data supports the role of XRCC1 as a predictive marker for therapy response in the multimodality therapy of patients with locally advanced rectal cancer. Single-nucleotide polymorphism XRCC1 A399G (rs25487) could be applied to individualize treatment strategies.

Posttranscriptional regulation of cancer traits by HuR

Cancer-related gene expression programs are strongly influenced by posttranscriptional mechanisms. The RNA-binding protein HuR is highly abundant in many cancers. Numerous HuR-regulated mRNAs encode proteins implicated in carcinogenesis. Here, we review the collections of HuR target mRNAs that encode proteins responsible for implementing five major cancer traits. By interacting with specific mRNA subsets, HuR enhances the levels of proteins that (1) promote cell proliferation, (2) increase cell survival, (3) elevate local angiogenesis, (4) help the cancer cell evade immune recognition, and (5) facilitate cancer cell invasion and metastasis. We propose that HuR exerts a tumorigenic function by enabling these cancer phenotypes. We discuss evidence that links HuR to several specific cancers and suggests its potential usefulness in cancer diagnosis, prognosis, and therapy.

miR-192/miR-215 influence 5-fluorouracil resistance through cell cycle-mediated mechanisms complementary to its post-transcriptional thymidilate synthase regulation

Thymidylate synthase (TYMS) is a target of the most widely used chemotherapeutic agents against gastrointestinal malignancies, the fluoropyrimidine-based therapy. TYMS expression levels have been identified as predictive biomarkers for 5-fluoruracil (FU) response in colorectal cancer, but their clinical utility remains controversial. The complexity of fluoropyrimidine response must require more mechanisms that currently have not been completely elucidated. In this context, microRNAs (miRNA) may play a role in modulating chemosensitivity. By carrying out an in silico analysis coupled to experimental validation, we detected that miR-192 and miR-215 target TYMS expression in colorectal cancer cell lines. However, downregulation of TYMS by these miRNAs does not sensitize colorectal cancer cell lines to FU treatment. The overexpression of miR-192/215 significantly reduces cell proliferation by targeting cell cycle progression. This effect was partially associated with p53 status, because reduction of cell proliferation and cell cycle arrest was associated with p21 and p27 induction. The decrease of S-phase cells by these miRNAs mitigates the effects of S phase-specific drugs and suggests that other mechanisms different from TYMS overexpression are essential to direct FU resistance. Finally, ectopic expression of miR-192/215 might have stronger impact to predict FU response than TYMS inhibition. Prospective studies to elucidate the role of these miRNAs as predictive biomarkers to FU are necessary.

Predictive value of Smac, VEGF and Ki-67 in rectal cancer treated with neoadjuvant therapy

The present study aimed to identify whether second mitochondria-derived activator of caspase (Smac), vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (Ki-67) expression in pre-treatment tumor biopsies are useful predictive markers of tumor response in patients with rectal cancer undergoing pre-operative chemoradiotherapy (CRT). Paraffin-embedded tissues obtained before and after therapy were evaluated by immunohistochemical staining for Smac, VEGF and Ki-67. The study evaluated the correlation of Smac, VEGF and Ki-67 immunoreactivity in tumor biopsies before treatment of tumor response to pre-operative CRT. Regarding Smac, patients with a favorable response to neoadjuvant CRT had higher pre-therapy levels (p=0.011). The level of Smac expression decreased after neoadjuvant therapy (p=0.044). However, VEGF expression was found to be negatively and significantly correlated with a favorable tumor response to neoadjuvant CRT (p=0.010). A transient increase in VEGF expression was detected in the resected specimens following neoadjuvant therapy (p=0.030). In addition, tumors with a low Ki-67 labeling index (Ki-67-LI) expression were found to be more sensitive to neoadjuvant therapy than those with a high expression of Ki-67-LI (p=0.034). In contrast to VEGF, the Ki-67 expression level decreased after neoadjuvant therapy. Smac, VEGF and Ki-67 expression levels, assessed immunohistochemically from pre-treatment tumor biopsies, may be useful predictive markers of rectal tumor response to pre-operative CRT.

Cetuximab and chemoradiation for rectal cancer--is the water getting muddy?

The epidermal growth factor receptor (EGFR) inhibitor cetuximab has been successfully combined with radical radiotherapy in head and neck cancer. In colorectal cancer, increased response rates are achieved by cetuximab and panitumumab within standard chemotherapy schedules, but not in chemoradiation regimens. This review examines the clinical evidence and potential mechanisms for an interaction when EGFR inhibitors are added to fluoropyrimidine-based chemoradiation in rectal adenocarcinoma.

METHODS

This review was compiled by searching PubMed and Medline for English language articles published until 2009 with established search strategies, supplemented by hand searching of abstracts from the proceedings of relevant international meetings. The primary outcome measure was pathological complete response (pCR).

RESULTS

Only 13 publications and three presentations in abstract of 13 phase I/II trials of preoperative chemoradiation with cetuximab in rectal cancer were identified. A total of 316 patients were identified who received cetuximab in combination with radiotherapy and 5-fluorouracil or capecitabine preoperatively. One hundred and thirty eight of these patients received either additional irinotecan or oxaliplatin. One study with panitumumab with safety but no efficacy results was identified, and two studies with gefinitib. The pCR rate ranged from 0-20%. The overall pooled pCR for cetuximab based chemoradiation was 9.1% (29/316). The rate of G3/G4 gastrointestinal toxicity, in terms of diarrhoea, varied from 5-30%, with an overall pooled rate of 47/313 (15%).

DISCUSSION

Potential reasons for the disappointing results of EGFR inhibition with fluoropyrimidine-based preoperative chemoradiation include a less critical role of repopulation in rectal adenocarcinoma using a non-curative radiation dose; or antagonistic effects on 5FU-based chemoradiation and oxaliplatin, if some cells arrest in G1 or G2-M and fail to pass through S phase.

CONCLUSION

Cetuximab combined with fluoropyrimidine-based chemoradiation is not currently recommended. A better understanding of the mechanisms involved in combinations of chemotherapy and radiotherapy might allow more effective future scheduling of biological and chemical agents in combination with radiation.