Prognostic impact of p21/waf1/cip1 in colorectal cancer

p21 Prevents the Exhaustion of CD4+ T Cells Within the Antitumor Immune Response Against Colorectal Cancer

BACKGROUND & AIMS

T cells are crucial for the antitumor response against colorectal cancer (CRC). T-cell reactivity to CRC is nevertheless limited by T-cell exhaustion. However, molecular mechanisms regulating T-cell exhaustion are only poorly understood.

METHODS

We investigated the functional role of cyclin-dependent kinase 1a (Cdkn1a or p21) in cluster of differentiation (CD) 4+ T cells using murine CRC models. Furthermore, we evaluated the expression of p21 in patients with stage I to IV CRC. In vitro coculture models were used to understand the effector function of p21-deficient CD4+ T cells.

RESULTS

We observed that the activation of cell cycle regulator p21 is crucial for CD4+ T-cell cytotoxic function and that p21 deficiency in type 1 helper T cells (Th1) leads to increased tumor growth in murine CRC. Similarly, low p21 expression in CD4+ T cells infiltrated into tumors of CRC patients is associated with reduced cancer-related survival. In mouse models of CRC, p21-deficient Th1 cells show signs of exhaustion, where an accumulation of effector/effector memory T cells and CD27/CD28 loss are predominant. Immune reconstitution of tumor-bearing Rag1-/- mice using ex vivo-treated p21-deficient T cells with palbociclib, an inhibitor of cyclin-dependent kinase 4/6, restored cytotoxic function and prevented exhaustion of p21-deficient CD4+ T cells as a possible concept for future immunotherapy of human disease.

CONCLUSIONS

Our data reveal the importance of p21 in controlling the cell cycle and preventing exhaustion of Th1 cells. Furthermore, we unveil the therapeutic potential of cyclin-dependent kinase inhibitors such as palbociclib to reduce T-cell exhaustion for future treatment of patients with colorectal cancer.

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.

Chimeric TβRII-SE/Fc overexpression by a lentiviral vector exerts strong antitumoral activity on colorectal cancer-derived cell lines in vitro and on xenografts

The TGF signaling pathway is a key regulator of cancer progression. In this work, we report for the first time the antitumor activity of TβRII-SE/Fc, a novel peptibody whose targeting domain is comprised of the soluble endogenous isoform of the human TGF-β type II receptor (TβRII-SE). Overexpression of TβRIISE/Fc reduces in vitro cell proliferation and migration while inducing cell cycle arrest and apoptosis in human colorectal cancer-derived cell lines. Moreover, TβRII-SE/Fc overexpression reduces tumorigenicity in BALB/c nude athymic mice. Our results revealed that TRII-SE/Fc-expressing tumors were significantly reduced in size or were even incapable of developing. We also demonstrated that the novel peptibody has the ability to inhibit the canonical TGF-β and BMP signaling pathways while identifying SMAD-dependent and independent proteins involved in tumor progression that are modulated by TβRII-SE/Fc. These findings provide insights into the underlying mechanism responsible for the antitumor activity of TβRII-SE/Fc. Although more studies are required to demonstrate the effectiveness and safety of the novel peptibody as a new therapeutic for the treatment of cancer, our initial in vitro and in vivo results in human colorectal tumor-derived cell lines are highly encouraging. Our results may serve as the foundation for further research and development of a novel biopharmaceutical for oncology.

Cellular senescence in cancer: clinical detection and prognostic implications

Cellular senescence is a state of stable cell-cycle arrest with secretory features in response to cellular stress. Historically, it has been considered as an endogenous evolutionary homeostatic mechanism to eliminate damaged cells, including damaged cells which are at risk of malignant transformation, thereby protecting against cancer. However, accumulation of senescent cells can cause long-term detrimental effects, mainly through the senescence-associated secretory phenotype, and paradoxically contribute to age-related diseases including cancer. Besides its role as tumor suppressor, cellular senescence is increasingly being recognized as an in vivo response in cancer patients to various anticancer therapies. Its role in cancer is ambiguous and even controversial, and senescence has recently been promoted as an emerging hallmark of cancer because of its hallmark-promoting capabilities. In addition, the prognostic implications of cellular senescence have been underappreciated due to the challenging detection and sparse in and ex vivo evidence of cellular senescence in cancer patients, which is only now catching up. In this review, we highlight the approaches and current challenges of in and ex vivo detection of cellular senescence in cancer patients, and we discuss the prognostic implications of cellular senescence based on in and ex vivo evidence in cancer patients.

Chemosensitization of HT29 and HT29-5FU Cell Lines by a Combination of a Multi-Tyrosine Kinase Inhibitor and 5FU Downregulates ABCC1 and Inhibits PIK3CA in Light of Their Importance in Saudi Colorectal Cancer

Colorectal cancer (CRC) remains one of the main causes of death worldwide and in Saudi Arabia. The toxicity and the development of resistance against 5 fluorouracil 5FU pose increasing therapeutic difficulties, which necessitates the development of personalized drugs and drug combinations. Objectives: First, to determine the most important kinases and kinase pathways, and the amount of ABC transporters and KRAS in samples taken from Saudi CRC patients. Second, to investigate the chemosensitizing effect of LY294002 and HAA₂₀₂₀ and their combinations with 5FU on HT29, HT29-5FU, HCT116, and HCT116-5FU CRC cells, their effect on the three ABC transporters, cell cycle, and apoptosis, in light of the important kinase pathways resulting from the first part of this study. Methods: The PamChip^® peptide micro-array profiling was used to determine the level of kinase and targets in the Saudi CRC samples. Next, RT-PCR, MTT cytotoxicity, Western blotting, perturbation of cell cycle, annexin V, and immunofluorescence assays were used to investigate the effect on CRC, MRC5, and HUVEC cells. Results: The kinase activity profiling highlighted the importance of the PI3K/AKT, MAPK, and the growth factors pathways in the Saudi CRC samples. PIK3CA was the most overexpressed, and it was associated with increased level of mutated KRAS and the three ABC transporters, especially ABCC1 in the Saudi samples. Next, combining HAA₂₀₂₀ with 5FU exhibited the best synergistic and resistance-reversal effect in the four CRC cells, and the highest selectivity indices compared to MRC5 and HUVEC normal cells. Additionally, HAA₂₀₂₀ with 5FU exerted significant inhibition of ABCC1 in the four CRC cells, and inhibition of PIK3CA/AKT/MAPK7/ERK in HT29 and HT29-5FU cells. The combination also inhibited EGFR, increased the preG₁/S cell cycle phases, apoptosis, and caspase 8 in HT29 cells, while it increased the G₁ phase, p21/p27, and apoptosis in HT29-5FU cells. Conclusion: We have combined the PamChip kinase profiling of Saudi CRC samples with in vitro drug combination studies in four CRC cells, highlighting the importance of targeting PIK3CA and ABCC1 for Saudi CRC patients, especially given that the overexpression of PIK3CA mutations was previously linked with the lack of activity for the anti-EGFRs as first line treatment for CRC patients. The combination of HAA₂₀₂₀ and 5FU has selectively sensitized the four CRC cells to 5FU and could be further studied.

Endothelial sprouting, proliferation, or senescence: tipping the balance from physiology to pathology

Therapeutic modulation of vascular cell proliferation and migration is essential for the effective inhibition of angiogenesis in cancer or its induction in cardiovascular disease. The general view is that an increase in vascular growth factor levels or mitogenic stimulation is beneficial for angiogenesis, since it leads to an increase in both endothelial proliferation and sprouting. However, several recent studies showed that an increase in mitogenic stimuli can also lead to the arrest of angiogenesis. This is due to the existence of intrinsic signaling feedback loops and cell cycle checkpoints that work in synchrony to maintain a balance between endothelial proliferation and sprouting. This balance is tightly and effectively regulated during tissue growth and is often deregulated or impaired in disease. Most therapeutic strategies used so far to promote vascular growth simply increase mitogenic stimuli, without taking into account its deleterious effects on this balance and on vascular cells. Here, we review the main findings on the mechanisms controlling physiological vascular sprouting, proliferation, and senescence and how those mechanisms are often deregulated in acquired or congenital cardiovascular disease leading to a diverse range of pathologies. We also discuss alternative approaches to increase the effectiveness of pro-angiogenic therapies in cardiovascular regenerative medicine.

BMP3 suppresses colon tumorigenesis via ActRIIB/SMAD2-dependent and TAK1/JNK signaling pathways

Background

BMP3 gene is often found hypermethylated and hence inactivated in several types of cancers including colorectal cancer (CRC), indicating that it has a suppressor role in carcinogenesis. Though BMP3 is a reliable biomarker for screening CRC, the molecular mechanism of BMP3 in carcinogenesis remains largely unknown.

Methods

The expression level of BMP3 was examined by immunohistochemistry staining and western blot. Methylation-specific PCR (MSP) and real-time quantitative MSP were used to test the hypermethylation status of BMP3 gene. Analyses of BMP3 function in colon cancer cell proliferation, migration, invasion, and apoptosis were performed using HCT116 and KM12 cells. BMP3 was further knocked down or overexpressed in CRC cells, and the effects on cell growth of xenograft tumors in nude mice were assessed. Co-immunoprecipitation and immunofluorescence staining were used to analyze the association between BMP3 and BMPR2 or BMP3 and ActRIIB. Microarray analysis was performed to identify most differentially expressed genes and pathways regulated by BMP3. The BMP3-regulated SMAD2-dependent signaling pathway and TAK1/JNK signal axes were further investigated by quantitative PCR and western blot.

Results

BMP3 gene was hypermethylated and its expression was downregulated in both CRC tissues and cell lines. Expressing exogenous BMP3 in HCT116 inhibited cell growth, migration, and invasion and increased rate of apoptosis both in vitro and in vivo. However, shRNA-mediated attenuation of endogenous BMP3 in KM12 reversed such inhibitory and apoptotic effects. Furthermore, BMP3 could bind to ActRIIB, an activin type II receptor at the cellular membrane, thereby activating SMAD2-dependent pathway and TAK1/JNK signal axes to regulate downstream targets including caspase-7, p21, and SMAD4 that play crucial roles in cell cycle control and apoptosis.

Conclusions

Our study reveals a previously unknown mechanism of BMP3 tumor suppression in CRC and provides a rationale for future investigation of BMP3 as a potential target for the development of novel therapeutic agents to fight CRC.

Discovery of Dihydropyrrol-2-ones as Novel G0/G1-Phase Arresting Agents Inducing Apoptosis

A series of dihydropyrrol-2-ones (DHPs) were designed and synthesized via an efficient multicomponent reaction at room temperature for evaluation of their bioactivities against four human cancer lines (MCF-7, RKO, HeLa, and A549) in vitro. Preliminary structure-activity relationship studies showed that R4 = 3-MeO-4-OH-Ph is a crucial group for increasing cytotoxicities against RKO cells and the influences of R1-R3 depend on their combination. It was found that DHPs 5a, 5q, and 5s showed the best antiproliferative activities against A549, RKO, and all four studied cell lines, respectively (IC50 = 1.9, 0.8, and 0.9-2.4 μM). They can be used as new lead compounds for developing potentially selective or broad spectrum anticancer agents. 5q proves as a potent G0/G1-phase arresting agent inducing cell apoptosis by increasing/decreasing the levels of p53 and p21/cyclin D1.

Human Colorectal Cancer from the Perspective of Mouse Models

Colorectal cancer (CRC) is a heterogeneous disease that includes both hereditary and sporadic types of tumors. Tumor initiation and growth is driven by mutational or epigenetic changes that alter the function or expression of multiple genes. The genes predominantly encode components of various intracellular signaling cascades. In this review, we present mouse intestinal cancer models that include alterations in the Wnt, Hippo, p53, epidermal growth factor (EGF), and transforming growth factor β (TGFβ) pathways; models of impaired DNA mismatch repair and chemically induced tumorigenesis are included. Based on their molecular biology characteristics and mutational and epigenetic status, human colorectal carcinomas were divided into four so-called consensus molecular subtype (CMS) groups. It was shown subsequently that the CMS classification system could be applied to various cell lines derived from intestinal tumors and tumor-derived organoids. Although the CMS system facilitates characterization of human CRC, individual mouse models were not assigned to some of the CMS groups. Thus, we also indicate the possible assignment of described animal models to the CMS group. This might be helpful for selection of a suitable mouse strain to study a particular type of CRC.

Molecular signatures for CCN1, p21 and p27 in progressive mantle cell lymphoma

Mantle cell lymphoma (MCL) is a comparatively rare non-Hodgkin's lymphoma characterised by overexpression of cyclin D1. Many patients present with or progress to advanced stage disease within 3 years. MCL is considered an incurable disease with median survival between 3 and 4 years. We have investigated the role(s) of CCN1 (CYR61) and cell cycle regulators in progressive MCL. We have used the human MCL cell lines REC1 < G519 < JVM2 as a model for disease aggression. The magnitude of CCN1 expression in human MCL cells is REC1 > G519 > JVM2 cells by RQ-PCR, depicting a decrease in CCN1 expression with disease progression. Investigation of CCN1 isoform expression by western blotting showed that whilst expression of full-length CCN1 was barely altered in the cell lines, expression of truncated forms (18-20 and 28-30 kDa) decreased with disease progression. We have then demonstrated that cyclin D1 and cyclin dependent kinase inhibitors (p21^CIP1and p27^KIP1) are also involved in disease progression. Cyclin D1 was highly expressed in REC1 cells (OD: 1.0), reduced to one fifth in G519 cells (OD: 0.2) and not detected by western blotting in JVM2 cells. p27^KIP1 followed a similar profile of expression as cyclin D1. Conversely, p21^CIP1 was absent in the REC1 cells and showed increasing expression in G519 and JVM2 cells. Subcellular localization detected p21^CIP1/ p27^KIP1 primarily within the cytoplasm and absent from the nucleus, consistent with altered roles in treatment resistance. Dysregulation of the CCN1 truncated forms are associated with MCL progression. In conjunction with reduced expression of cyclin D1 and increased expression of p21, this molecular signature may depict aggressive disease and treatment resistance.

Selenoprotein H controls cell cycle progression and proliferation of human colorectal cancer cells

Selenoprotein H (SELENOH) is supposed to be involved in redox regulation as well as in tumorigenesis. However, its role in healthy and transformed cells of the gastrointestinal tract remains elusive. We analyzed SELENOH expression in cells depending on their selenium supply and differentiation status and found that SELENOH expression was increased in tumor tissue, in undifferentiated epithelial cells from mice and in colorectal cancer lines as compared to more differentiated ones. Knockdown studies in human colorectal cancer cells revealed that repression of SELENOH decreased cellular differentiation and increased proliferation and migration. In addition, SELENOH knockdown cells have a higher competence to form colonies or tumor xenografts. In parallel, they show a faster cell cycle transition. The high levels of SELENOH in tumors as well as in undifferentiated, proliferative cells together with its inhibitory effects on proliferation and G1/S phase transition suggest SELENOH as a key regulator for cell cycle progression and for prevention of uncontrolled proliferation. As SELENOH expression is highly dependent on the selenium status, effects of selenium supplementation on cancer initiation and progression appear to involve SELENOH.

Down-Regulated LncRNA-HOTAIR Suppressed Colorectal Cancer Cell Proliferation, Invasion, and Migration by Mediating p21

BACKGROUND AND AIM

HOX transcript antisense intergenic RNA (HOTAIR) is a relatively well-understood RNA, which plays a central role in the pathogenesis of various tumors. The aim of the present study was to investigate the effect by which HOTAIR acts to influence the biological processes of colorectal cancer (CRC) through p21.

METHODS

Reverse transcription quantitative polymerase chain reaction and Western blot methods were employed to provide verification regarding the changes in HOTAIR, PCNA, Ki67, p21, cyclin E, and CDK2 among the CRC tissues and cells. The correlation between the clinicopathological characteristics of patients and expression of HOTAIR and p21 was subsequently evaluated, followed by an analysis into the effects of HOTAIR on the biological processes of M5 cells.

RESULTS

HOTAIR was found to be expressed at high levels, while p21 was determined to be at a low level among both the CRC tissues and the CRC cell lines. The expressions of HOTAIR and p21 were determined to be related to lymph node metastasis, tumor node metastasis, Dukes staging, distant metastases, histological types, and the degree of differentiation. Cells transfected with HOTAIR siRNA displayed inhibited rates of proliferation, invasion, and migration, as well as decreased cyclin E and CDK2, while apoptosis and p21 were increased.

CONCLUSION

The principal findings demonstrated that down-regulation of HOTAIR elicits an inhibitory effect on proliferation, invasion, and migration, while promoting the apoptosis of CRC cells through the up-regulation of p21. We believe that HOTAIR could represent a novel target for the treatment of CRC.

miR-19 targeting of PTEN mediates butyl benzyl phthalate-induced proliferation in both ER(+) and ER(-) breast cancer cells

Breast cancer is the most common cancer among women worldwide. Butyl benzyl phthalate (BBP) is ubiquitous in human's environment, and is strongly linked to breast cancer development. microRNA (miRNA) is an important regulator of target genes. So far, no studies have been reported yet to reveal the action of miRNAs in BBP-mediated breast cancer cell proliferation. In this study, we showed that BBP induced proliferation of both ER(+) MCF-7 and ER(-) MDA-MB-231 breast cancer cells, proved by increased cell viability, transition of cell cycle from G1 to S phase, upregulation of proliferating cell nuclear antigen (PCNA) and Cyclin D1, and downregulation of p21. Meanwhile, the expression of oncogenic miR-19a/b and PTEN/AKT/p21 axis was also modulated by BBP. Furthermore, for the first time we revealed that miR-19 played crucial role in the promoting effect of BBP on breast cancer cells through targeting PTEN 3'UTR. Findings from this study could provide an important new perspective on the molecular mechanisms through which BBP exerts its promoting effect on breast cancer as well as its target intervention.

Evaluating the prognostic value and functional roles of transcription factor AP4 in colorectal cancer

The basic helix-loop-helix transcription factor AP4 (TFAP4) gene serves an important function in the genesis and progression of tumors. However, few studies to date have defined the role of this gene in colorectal cancer (CRC). The aim of the present study was to assess the expression of TFAP4 in CRC and its impact on the prognosis of patients with CRC. In the present study, the expression of TFAP4 was detected in 30 matched pairs of fresh CRC tissues, 187 cases of clinical paraffin-embedded CRC tissues and CRC cell lines using the reverse transcriptase-quantitative polymerase chain reaction, immunohistochemistry or western blot analysis. Survival analysis was based on TFAP4 expression. The effects of TFAP4 on CRC cell function were investigated by ectopic expression or knockdown of TFAP4 in vitro. TFAP4 expression was revealed to be increased in human CRC tissues and cell lines. The overall survival (OS) time of patients with high TFAP4 expression was significantly decreased compared with patients with low TFAP4 expression (P<0.001). In addition, TFAP4 was revealed to be an independent prognostic factor for the OS time of patients with CRC (hazard ratio, 2.607; 95% confidence interval, 1.469-4.627; P=0.001). Ectopic TFAP4 expression promoted CRC cell proliferation, migration and invasion in vitro, and the silencing of TFAP4 expression resulted in the inhibition of these events. These results demonstrated that TFAP4, which was overexpressed in CRC tissues and cell lines, increased the malignant potential of CRC cells and may serve as an indicator for poor prognosis in patients with CRC.

P21, COX-2, and E-cadherin are potential prognostic factors for esophageal squamous cell carcinoma

Much research effort has been devoted to identifying prognostic factors for esophageal squamous cell carcinoma (ESCC) by immunohistochemistry; however, no conclusive findings have been reached thus far. We hypothesized that certain molecules identified in previous studies might serve as useful prognostic markers for ESCC. Therefore, the aim of the current study was to validate the most relevant markers showing potential for ESCC prognosis in our prospective esophageal cancer database. A literature search was performed using the PubMed database for papers published between 1980 and 2015 using the following key words: 'esophageal cancer,' 'prognosis,' and 'immunohistochemistry.' Literature selection criteria were established to identify the most widely studied markers, and we further validated the selected markers in a cohort from our single-surgeon team, including 153 esophageal cancer patients treated from 2000 to 2010. A total of 1799 articles were identified, 82 of which met the selection criteria. Twelve markers were found to be the most widely studied, and the validation results indicated that only P21, COX-2, and E-cadherin were independent prognostic factors for ESCC patients in this series. The systemic review and cohort validation suggest that P21, COX-2, and E-cadherin are potential prognostic factors for ESCC, paving the way for more targeted prospective validation in the future.

The Differential Immunohistochemical Expression of p53, c-Jun, c-Myc, and p21 Between HCV-related Hepatocellular Carcinoma With and Without Cirrhosis

Hepatocellular carcinoma (HCC) constitutes 70.48% of all liver tumors among Egyptians with multifactorial etiology and complex pathogenesis. HCV infection is the most common risk factor of HCC in Egypt, which commonly develops on top of cirrhosis (HCC-C); however, 15% to 20% of HCC are reported to arise in noncirrhotic livers (HCC-NC). This study aimed to explore the differences in the immunohistochemical expression of p53, c-Jun, c-Myc, and p21 between HCC-C and HCC-NC to verify the underlying molecular pathways and to study their role in hepatocarcinogenesis. This study investigated 103 cases of HCC (86 cases of HCC-C and 17 cases HCC-NC including tumorous and nontumorous tissues) together with 10 cases of chronic hepatitis and 10 cases of pure cirrhosis as control groups. Zero, 100%, 100%, and 50% of chronic hepatitis cases were positive for p53, c-Jun, c-Myc, and p21, respectively. All cirrhotic cases were negative for p53 and c-Jun, whereas they were all positive for c-Myc and p21. A total of 41%, 11.65%, 86.4%, and 57.3% of HCC cases showed p53, c-Jun, c-Myc, and p21 expression, respectively. The only difference between HCC-C and HCC-NC was the H-score values of p21 expression, which were higher in HCC-C compared with HCC-NC (P=0.03). HCV-related HCC commonly develops on top of cirrhosis with a minority develops on top of noncirrhotic liver. Only p21 pathway appears to be upregulated in favor of HCC-C than HCC-NC. p53 is considered as a late-event molecular carcinogen, whereas p21 and c-Myc may serve as early-event molecular carcinogen in HCC. The oncogenic role of p21 may be related to its cytoplasmic localization and its promotion of c-Myc expression. Progressive increase in the intensity of c-Myc expression from chronic hepatitis to cirrhosis to HCC may refer to its role as a multistep regulator of hepatocarcinogenesis. The marked reduction of c-Jun in HCC may refer to its tumor suppressor activity.

Up-regulation of miR-95-3p in hepatocellular carcinoma promotes tumorigenesis by targeting p21 expression

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers. To elucidate new regulatory mechanisms for heptocarcinogenesis, we investigated the regulation of p21, a cyclin-dependent kinase (CDK) inhibitor encoded by CDKN1A, in HCC. The expression level of p21 is decreased with the progression of HCC. Luciferase assays with a luciferase-p21-3' UTR reporter and its serial deletions identified a 15-bp repressor element at the 3'-UTR of CDKN1A, which contains a binding site for miR-95-3p. Mutation of the binding site eliminated the regulatory effect of miR-95-3p on p21 expression. Posttranscriptional regulation of p21 expression by miR-95-3p is mainly on the protein level (suppression of translation). Overexpression of miR-95-3p in two different HCC cell lines, HepG2 and SMMC7721, significantly promoted cell proliferation, cell cycle progression and cell migration, whereas a miR-95-3p specific inhibitor decreased cell proliferation, cell cycle progression and cell migration. The effects of miR-95-3p on cellular functions were rescued by overexpression of p21. Overexpression of miR-95-3p promoted cell proliferation and tumor growth in HCC xenograft mouse models. Expression of miR-95-3p was significantly higher in HCC samples than in adjacent non-cancerous samples. These results demonstrate that miR-95-3p is a potential new marker for HCC and regulates hepatocarcinogenesis by directly targeting CDKN1A/p21 expression.

MicroRNA-92a Promotes Colorectal Cancer Cell Growth and Migration by Inhibiting KLF4

Colorectal cancer (CRC) is the third most common malignancy with high mortality around the world. However, the biological mechanism of CRC carcinogenesis is not completely known. In the present study, we determined the role of miR-92a in the regulation of CRC cell motility. Expression of miR-92a is aberrantly upregulated in human CRC tissues and cultured cells, as shown by RT-PCR analysis. The effects of miR-92a on the proliferation and migration of human CRC SW620 and LoVo cells were measured by CCK-8 and Transwell assay, respectively. Results showed that the proliferation and migration capacity of both SW620 and LoVo cells were significantly increased by miR-92a mimic transfection but reduced by miR-92a inhibition. Additionally, KLF4 was identified as a direct target of miR-92a in CRC cells through bioinformatics and luciferase reporter analysis. KLF4 overexpression attenuated the effects of miR-92a on the regulation of CRC cell motility. Further studies suggested that the cell cycle inhibitor p21 was aberrantly downregulated in CRC cells, whereas this inhibition was reversed by miR-92a inhibitor. In conclusion, our data demonstrated that miR-92a may play a positive role in the colorectal carcinogenesis by promoting the proliferation and migration of CRC cells through targeting KLF4 as well as downstream p21. This could be an alternative therapeutic target for CRC.

MiR-106b induces cell radioresistance via the PTEN/PI3K/AKT pathways and p21 in colorectal cancer

BACKGROUND

Radioresistance is a challenge in the treatment of patients with colorectal cancer (CRC). Individuals display different therapeutic responses to preoperative radiotherapy, and the need of targeted therapies is urgent. MicroRNAs (miRNAs) are involved in essential biological activities, including chemoresistance and radioresistance. Several research studies have indicated that miRNA played an important role in sensitizing cells to ionizing radiation (IR). MiR-106b, a member of the miR-106b-25 cluster, is frequently dysregulated in many human cancers, including CRC. However, the function of miR-106b in radioresistance is currently poorly understood.

METHODS

A series of in vitro and in vivo studies were performed to investigate the roles of miR-106b on cell radioresistance in CRC.

RESULTS

We found overexpression of miR-106b could induce resistance to IR in vitro and in vivo in SW620 cells. Correspondingly, knocking down miR-106b in SW480 yielded the opposite effect. In addition, overexpression of miR-106b could enhance the tumour-initiating cell capacity without or with IR condition, such as the colony sphere formation capacity and the upregulation of stemness-related genes (CD133, Sox2). We further identified PTEN and p21 as novel direct targets of miR-106b by using target prediction algorithms and a luciferase assay. Overexpression of miR-106b reduced the expression of PTEN and p21 and increased the expression of p-AKT, which is a downstream of PTEN. Restoring the expression of PTEN or p21 in stably miR-106b-overexpressed cells could rescue the effect of miR-106b on cell radioresistance. Together, the acquisition of tumour-initiating cell capacity endowed CRC cells with the potential of resistance to irradiation.

CONCLUSIONS

These observations illustrated that miR-106b could induce cell radioresistance by directly targeting PTEN and p21, this process was accompanied by tumour-initiating cell capacity enhancement, which is universally confirmed to be associated with radioresistance. Our data suggested that miR-106b at least partly induces cell radioresistance in CRC.

RNA sequencing supports distinct reactive oxygen species-mediated pathways of apoptosis by high and low size mass fractions of Bay leaf (Lauris nobilis) in HT-29 cells

Anti-proliferative and pro-apoptotic effects of Bay leaf (Laurus nobilis) in mammalian cancer and HT-29 adenocarcinoma cells have been previously attributed to effects of polyphenolic and essential oil chemical species. Recently, we demonstrated differentiated growth-regulating effects of high (HFBL) versus low molecular mass (LFBL) aqueous fractions of bay leaf and now confirm by comparative effects on gene expression, that HFBL and LFBL suppress HT-29 growth by distinct mechanisms. Induction of intra-cellular lesions including DNA strand breakage by extra-cellular HFBL, invoked the hypothesis that iron-mediated reactive oxygen species with capacity to penetrate cell membrane, were responsible for HFBL-mediated effects, supported by equivalent effects of HFBL in combination with γ radiation. Activities of HFBL and LFBL were interpreted to reflect differentiated responses to iron-mediated reactive oxygen species (ROS), occurring either outside or inside cells. In the presence of LFBL, apoptotic death was relatively delayed compared with HFBL. ROS production by LFBL mediated p53-dependent apoptosis and recovery was suppressed by promoting G1/S phase arrest and failure of cellular tight junctions. In comparison, intra-cellular anti-oxidant protection exerted by LFBL was absent for extra-cellular HFBL (likely polysaccharide-rich), which potentiated more rapid apoptosis by producing DNA double strand breaks. Differentiated effects on expression of genes regulating ROS defense and chromatic condensation by LFBL versus HFBL, were observed. The results support ferrous iron in cell culture systems and potentially in vivo, can invoke different extra-cellular versus intra-cellular ROS-mediated chemistries, that may be regulated by exogenous, including dietary species.

The opposite prognostic significance of nuclear and cytoplasmic p21 expression in resectable gastric cancer patients

BACKGROUND

Protein p21(Cip1/Waf1) is a cyclin-dependent kinase inhibitor, which plays important roles in cell cycle arrest, senescence, and apoptosis. Interestingly, the nuclear and cytoplasmic p21 executes various functions in the cell. In this study, we investigated the prognostic impact of subcellular p21 expression in gastric cancer (GC).

METHODS

Expressions of subcellular p21 was assessed by immunohistochemistry using a tissue microarray in a training cohort and it went into a second testing cohort and finally to a validating cohort. Prognostic and predictive role of subcellular p21 expression status was evaluated. We also studied the roles of subcellular p21 in GC cell migration and invasion.

RESULTS

Nuclear and cytoplasmic p21 protein levels were significantly reduced and increased in GC lesions compared with adjacent non-cancerous tissues, respectively. Low nuclear p21 or high cytoplasmic p21 expression significantly correlated with shorter overall survival (OS), as well as with clinicopathologic characteristics in patients. Multivariate regression analysis showed that low nuclear and high cytoplasmic p21 expression, separately and together, were independent negative markers of OS. Finally, we found that nuclear p21 inhibits but cytoplasmic p21 promotes cell migration and invasion abilities.

CONCLUSIONS

These findings suggest that nuclear and cytoplasmic p21 protein expression in tumor are novel candidate prognostic markers in resectable human gastric carcinoma, and they exert distinct roles in cell migration and invasion.

PHF2 histone demethylase acts as a tumor suppressor in association with p53 in cancer

Plant homeodomain finger 2 (PHF2) has a role in epigenetic regulation of gene expression by demethylating H3K9-Me2. Several genome-wide studies have demonstrated that the chromosomal region including the PHF2 gene is often deleted in some cancers including colorectal cancer, and this finding encouraged us to investigate the tumor suppressive role of PHF2. As p53 is a critical tumor suppressor in colon cancer, we tested the possibility that PHF2 is an epigenetic regulator of p53. PHF2 was associated with p53, and thereby, promoted p53-driven gene expression in cancer cells under genotoxic stress. PHF2 converted the chromatin that is favorable for transcription by demethylating the repressive H3K9-Me2 mark. In an HCT116 xenograft model, PHF2 was found to be required for the anticancer effects of oxaliplatin and doxorubicin. In PHF2-deficient xenografts, p53 expression was profoundly induced by both drugs, but its downstream product p21 was not, suggesting that p53 cannot be activated in the absence of PHF2. To find clinical evidence about the role of PHF2, we analyzed the expressions of PHF2, p53 and p21 in human colon cancer tissues and adjacent normal tissues from patients. PHF2 was downregulated in cancer tissues and PHF2 correlated with p21 in cancers expressing functional p53. Colon and stomach cancer tissue arrays showed a positive correlation between PHF2 and p21 expressions. Informatics analyses using the Oncomine database also supported our notion that PHF2 is downregulated in colon and stomach cancers. On the basis of these findings, we propose that PHF2 acts as a tumor suppressor in association with p53 in cancer development and ensures p53-mediated cell death in response to chemotherapy.

Cables1 controls p21/Cip1 protein stability by antagonizing proteasome subunit alpha type 3

The cyclin-dependent kinase inhibitor 1A (CDKN1A), p21/Cip1, is a vital cell cycle regulator, dysregulation of which has been associated with a large number of human malignancies. One critical mechanism that controls p21 function is through its degradation, which allows the activation of its associated cell cycle promoting kinases, CDK2 and CDK4. Thus, delineating how p21 is stabilized and degraded will enhance our understanding of cell growth control and offer a basis for potential therapeutic interventions. Here, we report a novel regulatory mechanism that controls the dynamic status of p21 through its interaction with Cdk5 and Ablenzyme substrate 1 (Cables1). Cables1 has a proposed role as a tumor suppressor. We found that upregulation of Cables1 protein was correlated with increased half-life of p21 protein, which was attributed to Cables1/p21 complex formation and supported by their co-localization in the nucleus. Mechanistically, Cables1 interferes with the proteasome (Prosome, Macropain) subunit alpha type 3 (PSMA3) binding to p21 and protects p21 from PSMA3-mediated proteasomal degradation. Moreover, silencing of p21 partially reverses the ability of Cables1 to induce cell death and inhibit cell proliferation. In further support of a potential pathophysiological role of Cables1, the expression level of Cables1 is tightly associated with p21 in both cancer cell lines and human lung cancer patient tumor samples. Together, these results suggest Cables1 as a novel p21 regulator through maintaining p21 stability, and support the model that the tumor suppressive function of Cables1 occurs at least in part through enhancing the tumor suppressive activity of p21.

Vitamin B₆ activates p53 and elevates p21 gene expression in cancer cells and the mouse colon

Increasing evidence indicates vitamin B6 acts as a protective factor against colon cancer. However, the mechanisms of the effect of vitamin B6 are poorly understood. The present preliminary study using DNA microarray and real-time PCR indicates p21 mRNA is upregulated in human colon carcinoma (HT29) cells exposed to pyridoxal (PL, 500 µM). A similar effect was observed in human epithelial colorectal adenocarcinoma (Caco2) cells, human colon adenocarcinoma (LoVo) cells, human embryonic kidney (HEK293T) cells, and human hepatoma (HepG2) cells. Adding other B6-vitamers such as pyridoxal 5'-phosphate (PLP), pyridoxine (PN), and pyridoxamine (PM) caused no such effect. In order to understand the mechanism of higher mRNA expression of p21 by PL, effect of PL on the p53 activation was examined (the upstream factor for p21 mRNA transcription) in HT29 cells, LoVo cells, and HepG2 cells. PL increased the phosphorylated p53 protein levels (active form) in whole-cell lysates and the nuclei of the cells. Noteworthy, the consumption of a vitamin B6-deficient diet for 5 weeks significantly reduced p21 mRNA levels and tended to reduce phosphorylated p53 protein levels (P=0.053) in the colons of mice compared to a diet with adequate vitamin B6. Thus, these results suggest vitamin B6 plays a role in increasing p21 gene expression via p53 activation in several cancer cells and the mouse colon.

Downregulation of p21 in myelodysplastic syndrome is associated with p73 promoter hypermethylation and indicates poor prognosis

OBJECTIVES

p21 Can both promote and inhibit tumorigenic processes. We explored the role of p21 in myelodysplastic syndrome (MDS).

METHODS

In this study, we analyzed p21 expression and p73 methylation in 88 patients with de novo MDS.

RESULTS

We found decreased expression of the p21 gene in higher-risk MDS compared with lower-risk groups or healthy controls (P < .05). Patients with p73 methylation had lower p21 than those in the unmethylated group (P < .001). Moreover, there was a significantly positive correlation between p73 and p21 expression in MDS (r = 0.436, P < .001). In vitro assays further confirm the role of p73 methylation in p21 expression. Compared with patients with normal expression levels of p21, patients with lower p21 expression levels experienced much higher rates of transformation to acute myeloid leukemia and lower overall survival both in univariate as well as multivariate analyses.

CONCLUSIONS

Our results suggest p21 expression may serve as a new biomarker to predict clinical outcome in patients with MDS.

Thymidylate synthase expression and p21(WAF1)/p53 phenotype of colon cancers identify patients who may benefit from 5-fluorouracil based therapy

Background

Studies on the expression of thymidylate synthase (TS) in colorectal cancers (CRCs) have failed to provide unequivocal prognostic or predictive information. Here, we assessed the prognostic significance of TS expression in Astler-Coller stage B2 and C CRCs defined by a p21^WAF1/p53 immunophenotype in patients subjected to 5-fluorouracil (5FU)-based adjuvant therapy.

Methods

A cohort of 189 CRCs was asssessed for TS, p21^WAF1 and p53 expression on tissue microarrays using immunohistochemistry, and associations with disease-free survival (DFS) and overall survival (OS) of the patients were assessed using univariate and multivariate analyses.

Results

TS expression led to the stratification of patients with colon cancer, but not rectal cancer, with immunophenotypes other than p21^WAF1+/p53- (referred to as P&P) into subgroups characterized by a worse (P&P TS+) and a better (P&P TS-) DFS and OS, in univariate (P = 0.006 and P = 0.005, respectively) and multivariate (P = 0.0004 and P = 0.002, respectively) analyses. The p21^WAF1+/p53- immunophenotype was associated with a favorable prognosis, irrespective of TS expression.

Conclusions

The strong association observed between the P&P TS+ immunophenotype and a worse DFS and OS suggests a predictive significance of TS expression for 5FU-based adjuvant therapy in patients with colon cancers exhibiting the P&P immunophenotype. In addition, our findings suggest that the appropriate target for assessment of TS expression as a prognostic/predictive marker is a subgroup of colon cancers with an immunophenotype other than p21^WAF1+/p53-, and that only in this subgroup high TS expression is associated with an unfavorable DFS and OS. Therefore, we suggest that assessing TS expression in conjunction with p21^WAF1/p53 immunophenotyping of colon cancers may improve the selection of patients suitable for 5FU-based adjuvant chemotherapy.

Distinct expression pattern and post-transcriptional regulation of cell cycle genes in the glandular epithelia of avian ovarian carcinomas

The cell cycle system is controlled in a timely manner by three groups of cyclins, cyclin dependent kinases and cyclin dependent kinase inhibitors. Abnormal alterations of cell cycle regulatory mechanisms are a common feature of many diseases including numerous tumor types such as ovarian cancer. Although a variety of cell cycle regulatory genes are well known in mammalian species including human and mice, they are not well studied in avian species, especially in laying hens which are recognized as an excellent animal model for research relevant to human ovarian carcinogenesis. Therefore, in the present study, we focused on comparative expression and regulation of expression of candidate genes which might be involved in the cell cycle program in surface epithelial ovarian cancer in laying hens. Our current results indicate that expression levels of cell cycle gene transcripts are greater in cancerous as compared to normal ovaries. In particular, cyclin A2 (CCNA2), CCND1, CCND2, CCND3, CCNE2, cyclin dependent kinase 1 (CDK1), CDK3, CDK5, cyclin dependent kinases inhibitor 1A (CDKN1A) and CDKN1B were upregulated predominantly in the glandular epithelia of cancerous ovaries from laying hens. Further, several microRNAs (miRs), specifically miR-1798, miR-1699, miR-223 and miR-1744 were discovered to influence expression of CCND1, CCNE2, CDK1, and CDK3 mRNAs, respectively, via their 3′-UTR which suggests that post-transcriptional regulation of gene expression influences their expression in laying hens. Moreover, miR-1626 influenced CDKN1A expression and miR-222, miR-1787 and miR-1812 regulated CDKN1B expression via their 3′-UTR regions. Collectively, results of the present study demonstrate increased expression of cell cycle-related genes in cancerous ovaries of laying hens and indicate that expression of these genes is post-transcriptionally regulated by specific microRNAs.

DNA damage response pathways and cell cycle checkpoints in colorectal cancer: current concepts and future perspectives for targeted treatment

Although several drugs have been designed in the last few years to target specific key pathways and functions in colorectal cancer (CRC), the backbone of CRC treatment is still made up of compounds which rely on DNA damage to accomplish their role. DNA damage response (DDR) and checkpoint pathways are intertwined signaling networks that arrest cell cycle, recognize and repair genetic mistakes which arise during DNA replication and transcription, as well as through the exposure to chemical and physical agents that interact with nucleic acids. The good but highly variable activity of DNA damaging agents in the treatment of CRC suggests that intrinsic alterations in DDR pathways and cell cycle checkpoints may contribute differentially to the way cancer cells react to DNA damage. In the present review, our aim is to depict the recent advances in understanding the molecular basis of the activity of DNA damaging agents used for the treatment of CRC. We focus on the known and potential drug targets that are part of these complex and intertwined pathways. We describe the potential role of the checkpoints in CRC, and how their pharmacological manipulation could lead to chemopotentiation or synergism with currently used drugs. Novel therapeutic agents playing a role in DDR and checkpoint inhibition are assessed. We discuss the possible rationale for combining PARP inhibition with DNA damaging agents, and we address the link between DDR and EGFR pathways in CRC.

A WNT/p21 circuit directed by the C-clamp, a sequence-specific DNA binding domain in TCFs

The lymphoid enhancer factor 1/T cell factor (LEF/TCF) family of transcription factors are downstream effectors of the WNT signaling pathway, which drives colon tumorigenesis. LEF/TCFs have a DNA sequence-specific high-mobility group (HMG) box that binds Wnt response elements (WREs). The "E tail" isoforms of TCFs are alternatively spliced to include a second DNA binding domain called the C-clamp. We show that induction of a dominant negative C-clamp version of TCF1 (dnTCF1E) induces p21 expression and a stall in the growth of DLD1 colon cancer cells. Induction of a C-clamp mutant did not efficiently induce p21, nor did it stall cell growth. Microarray analysis revealed that induction of p21 by wild-type dnTCF1E (dnTCF1E(WT)) correlated with a decrease in expression of multiple p21 suppressors that act at multiple levels from transcription (SP5, YAP1, and RUNX1), RNA stability (MSI2), and protein stability (CUL4A). We show that the C-clamp is a sequence-specific DNA binding domain that can make contacts with 5'-RCCG-3' elements upstream or downstream of WREs. The C-clamp-RCCG interaction was critical for TCF1E-mediated transcriptional control of p21-connected target gene promoters. Our results indicate that a rapid-response WNT/p21 circuit is driven by C-clamp target gene selection.

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.

Combined loss of p21(waf1/cip1) and p27(kip1) enhances tumorigenesis in mice

The cell cycle inhibitors p21(Waf1/Cip1) and p27(Kip1) are frequently downregulated in many human cancers, and correlate with a worse prognosis. We show here that combined deficiency in p21 and p27 proteins in mice is linked to more aggressive spontaneous tumorigenesis, resulting in a decreased lifespan. The most common tumors developed in p21p27 double-null mice were endocrine, with a higher incidence of pituitary adenomas, pheochromocytomas and thyroid adenomas. The combined absence of p21 and p27 proteins delays the incidence of radiation-induced thymic lymphomas with a higher apoptotic rate, measured by active caspase-3 and cleaved PARP-1 immunoexpresion. These results provide experimental evidence for a cooperation of both cyclin-dependent kinase inhibitors in tumorigenesis in mice.

Cytoplasmic p21 is a potential predictor for cisplatin sensitivity in ovarian cancer

Background

P21^(WAF1/Cip1) binds to cyclin-dependent kinase complexes and inhibits their activities. It was originally described as an inhibitor of cancer cell proliferation. However, many recent studies have shown that p21 promotes tumor progression when accumulated in the cell cytoplasm. So far, little is known about the correlation between cytoplasmic p21 and drug resistance. This study was aimed to investigate the role of p21 in the cisplatin resistance of ovarian cancer.

Methods

RT-PCR, western blot and immunofluorescence were used to detect p21 expression and location in cisplatin-resistant ovarian cancer cell line C13* and its parental line OV2008. Regulation of cytoplasmic p21 was performed through transfection of p21 siRNA, Akt2 shRNA and Akt2 constitutively active vector in the two cell lines; their effects on cisplatin-induced apoptosis were evaluated by flow cytometry. Tumor tissue sections of clinical samples were analyzed by immunohistochemistry.

Results

p21 predominantly localizes to the cytoplasm in C13* compared to OV2008. Persistent exposure to low dose cisplatin in OV2008 leads to p21 translocation from nuclear to cytoplasm, while it had not impact on p21 localization in C13*. Knockdown of cytoplasmic p21 by p21 siRNA transfection in C13* notably increased cisplatin-induced apoptosis through activation of caspase 3. Inhibition of p21 translocation into the cytoplasm by transfection of Akt2 shRNA into C13* cells significantly increased cisplatin-induced apoptosis, while induction of p21 translocation into the cytoplasm by transfection of constitutively active Akt2 in OV2008 enhanced the resistance to cisplatin. Immunohistochemical analysis of clinical ovarian tumor tissues demonstrated that cytoplasmic p21 was negatively correlated with the response to cisplatin based treatment.

Conclusions

Cytoplasmic p21 is a novel biomarker of cisplatin resistance and it may represent a potential therapeutic target for ovarian tumors that are refractory to conventional treatment.

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.

Prediction and testing of biological networks underlying intestinal cancer

Colorectal cancer progresses through an accumulation of somatic mutations, some of which reside in so-called "driver" genes that provide a growth advantage to the tumor. To identify points of intersection between driver gene pathways, we implemented a network analysis framework using protein interactions to predict likely connections--both precedented and novel--between key driver genes in cancer. We applied the framework to find significant connections between two genes, Apc and Cdkn1a (p21), known to be synergistic in tumorigenesis in mouse models. We then assessed the functional coherence of the resulting Apc-Cdkn1a network by engineering in vivo single node perturbations of the network: mouse models mutated individually at Apc (Apc(1638N+/-)) or Cdkn1a (Cdkn1a(-/-)), followed by measurements of protein and gene expression changes in intestinal epithelial tissue. We hypothesized that if the predicted network is biologically coherent (functional), then the predicted nodes should associate more specifically with dysregulated genes and proteins than stochastically selected genes and proteins. The predicted Apc-Cdkn1a network was significantly perturbed at the mRNA-level by both single gene knockouts, and the predictions were also strongly supported based on physical proximity and mRNA coexpression of proteomic targets. These results support the functional coherence of the proposed Apc-Cdkn1a network and also demonstrate how network-based predictions can be statistically tested using high-throughput biological data.

Development and progression of colorectal neoplasia

A variety of genetic and molecular alterations underlie the development and progression of colorectal neoplasia (CRN). Most of these cancers arise sporadically due to multiple somatic mutations and genetic instability. Genetic instability includes chromosomal instability (CIN) and microsatellite instability (MSI), which is observed in most hereditary non-polyposis colon cancers (HNPCCs) and accounts for a small proportion of sporadic CRN. Although many biomarkers have been used in the diagnosis and prediction of the clinical outcomes of CRNs, no single marker has established value. New markers and genes associated with the development and progression of CRNs are being discovered at an accelerated rate. CRN is a heterogeneous disease, especially with respect to the anatomic location of the tumor, race/ethnicity differences, and genetic and dietary interactions that influence its development and progression and act as confounders. Hence, efforts related to biomarker discovery should focus on identification of individual differences based on tumor stage, tumor anatomic location, and race/ethnicity; on the discovery of molecules (genes, mRNA transcripts, and proteins) relevant to these differences; and on development of therapeutic approaches to target these molecules in developing personalized medicine. Such strategies have the potential of reducing the personal and socio-economic burden of CRNs. Here, we systematically review molecular and other pathologic features as they relate to the development, early detection, diagnosis, prognosis, progression, and prevention of CRNs, especially colorectal cancers (CRCs).

Sulforaphane Increases Cyclin-Dependent Kinase Inhibitor, p21 Protein in Human Oral Carcinoma Cells and Nude Mouse Animal Model to Induce G(2)/M Cell Cycle Arrest

Previously, our group reported that sulforaphane (SFN), a naturally occurring chemopreventive agent from cruciferous vegetables, effectively inhibits the proliferation of KB and YD-10B human oral squamous carcinoma cells by causing apoptosis. In this study, treatment of 20 and 40 microM of SFN for 12 h caused a cell cycle arrest in the G(2)/M phase. Cell cycle arrest induced by SFN was associated with a significant increase in the p21 protein level and a decrease in cyclin B expression, but there was no change in the cyclin A protein level. In addition, SFN increased the p21 promoter activity significantly. Furthermore, SFN induced p21 protein expression in a nude mouse xenograft model suggesting that SFN is a potent inducer of the p21 protein in human oral squamous carcinoma cells. These findings show that SFN is a promising candidate for molecular-targeting chemotherapy against human oral squamous cell carcinoma.

Genetic polymorphisms of p21 and risk of second primary malignancy in patients with index squamous cell carcinoma of the head and neck

p21 plays an important role in modulating cell cycle control, inducing apoptosis, and inhibiting cell growth, subsequently affecting cancer risk. We investigated the association between two putatively functional single-nucleotide polymorphisms (SNPs) of p21 (p21 C98A and p21 C70T) among 1282 patients diagnosed with incident squamous cell carcinoma of the head and neck (SCCHN) and risk of second primary malignancy (SPM) in an ongoing molecular epidemiology study. We used Log-rank test and Cox proportional hazard models to assess the association of these two SNPs with SPM-free survival and SPM risk. We found that patients with either p21 variant genotypes of the two polymorphisms had a significantly reduced SPM-free survival compared with patients with either p21 wild-type homozygous genotypes (Log-rank test, P = 0.0016). Compared with patients having the p21 98 CC and p21 70 CC genotypes, the patients having p21 98 CA/AA and p21 70 CT/TT variant genotypes had a significantly greater risk of developing SPM, respectively, [hazard ratio (HR) = 1.80, 95% CI = 1.14-2.82 for p21 C98A and HR = 1.82, 95% confidence interval (CI) = 1.16-2.85 for p21 C70T]. Moreover, after combining the variant genotypes of two SNPs, patients with variant genotypes had a significantly moderately increased risk for SPM compared with patients with no variant genotypes (HR = 2.00, 95% CI = 1.26-3.00), and the risk was particularly pronounced in several subgroups. Our results support an increased risk of SPM after index SCCHN with both p21 polymorphisms individually and in combination.

p21 expression in colon cancer and modifying effects of patient age and body mass index on prognosis

p21 (Cyclin-dependent kinase inhibitor-1A, CDKN1A or CIP1) plays a role in regulating cell cycle, and its expression is lost in most colorectal cancers. p21 Is related with energy balance status, cellular senescence, and stem cell aging. Thus, the influence of p21 loss on tumor behavior and clinical outcome may be modified by patient age and body mass index (BMI). Using 647 colon cancers in two independent prospective cohorts, p21 loss was observed in 509 (79%) tumors by immunohistochemistry. Cox proportional hazard models computed hazard ratio (HR) for death, adjusted for potential confounders, including p53, cyclin D1, KRAS, BRAF, PIK3CA, LINE-1 hypomethylation, CpG island methylator phenotype (CIMP), and microsatellite instability (MSI). p21 Loss was independently associated with low colon cancer-specific mortality [HR, 0.58; 95% confidence interval (95% CI), 0.38-0.89; adjusted for the covariates including MSI, CIMP, and LINE-1 methylation]. The prognostic effect of p21 loss differed significantly by age at diagnosis (P(interaction) < 0.0001) and BMI (P(interaction) = 0.002). The adjusted HR for cancer-specific mortality (p21 loss versus p21 expression) was 4.09 (95% CI, 1.13-14.9) among patients <60 year old and 0.37 (95% CI, 0.24-0.59) among patients >or=60 year old. The adverse prognostic effect of obesity was limited to p21-expressing cases (adjusted HR, 5.85; 95% CI, 2.28-15.0; BMI, >or=30 versus <30 kg/m(2)), but no such effect was observed among p21-lost cases. In conclusion, p21 loss in colon cancer is associated with longer survival among patients >or=60 year old, whereas it is associated with shorter survival among patients <60 year old. Patient BMI also differentially influences prognosis according to p21 CDKN1A status. Our data suggest host-tumor interactions influencing tumor aggressiveness.

ITF-2 is disrupted via allelic loss of chromosome 18q21, and ITF-2B expression is lost at the adenoma-carcinoma transition

BACKGROUND & AIMS

The ubiquitously expressed basic helix-loop-helix transcription factor ITF-2B has an important role in differentiation processes, and its transcription is regulated by beta-catenin. The ITF-2 gene is located in the chromosomal region 18q21; allelic loss of this locus occurs in 70% of colorectal cancers. We analyzed the expression, regulation, and function of ITF-2B in colorectal carcinogenesis.

METHODS

The loss-of-heterozygosity (LOH) status of 18q21 and expression of ITF-2B were studied in colorectal carcinomas using polymerase chain reaction-based methods and immunohistochemistry. The biologic effects of ITF-2B were studied in colorectal cancer cells. Reporter gene assays and chromatin immunoprecipitation were utilized to analyze effects of ITF-2B on gene transcription.

RESULTS

ITF-2B is strongly expressed in colon adenomas but frequently down-regulated in carcinomas because of LOH at 18q21. ITF-2B induces cell cycle arrest and regulates the expression of p21(Cip1) via newly identified E-boxes in the CDKN1A gene, independently of p53. Loss of ITF-2B expression correlates with loss of p21(Cip1) expression in primary colon carcinomas.

CONCLUSIONS

Accumulation of mutations and allelic losses are driving forces of colorectal carcinogenesis. ITF-2B, which is up-regulated during early colorectal carcinogenesis because of loss of adenomatous polyposis coli, is a target for LOH on chromosome 18q, along with deleted in colorectal carcinoma and Smad4. This finding, along with the fact that ITF-2B is a regulator of the key cell cycle inhibitor p21(Cip1), indicates that ITF-2B is a tumor suppressor that has an important function at the adenoma to carcinoma transition.

p21 in cancer: intricate networks and multiple activities

One of the main engines that drives cellular transformation is the loss of proper control of the mammalian cell cycle. The cyclin-dependent kinase inhibitor p21 (also known as p21WAF1/Cip1) promotes cell cycle arrest in response to many stimuli. It is well positioned to function as both a sensor and an effector of multiple anti-proliferative signals. This Review focuses on recent advances in our understanding of the regulation of p21 and its biological functions with emphasis on its p53-independent tumour suppressor activities and paradoxical tumour-promoting activities, and their implications in cancer.

Expression patterns of cyclins D1, E and cyclin-dependent kinase inhibitors p21waf1/cip1, p27kip1 in colorectal carcinoma: correlation with other cell cycle regulators (pRb, p53 and Ki-67 and PCNA) and clinicopathological features

Aberrations in the cell cycle regulators are common features of many tumours and several have been shown to have prognostic significant in colorectal cancer. The expression patterns of cyclins D1 and E as well as cyclin-dependent kinase (CDK) inhibitors p21waf1/cip1 and p27kip1 and their interrelationship with other cell cycle checkpoint proteins [p53, pRb, Ki-67 and proliferative cell nuclear antigen (PCNA)] were investigated in colorectal cancer in order to ascertain coregulation and influence on tumour behaviour or survival. These molecular markers were localisated immunohistochemically using the monoclonal antibodies anticyclin D1 (DCS-6), anticyclin E (13A3), anti-p21 (4D10), anti-p27 (1B4), anti-p53 (DO7), anti-Rb (AB-5), MIB1 and PC10 in colorectal cancer tissue from 97 patients. Data were analysed statistically using the spss software program. Overexpression of cyclin D1, cyclin E and p21waf1/cip1 proteins (>5% positive neoplastic cells) was observed in 5.9%, 30% and 7.2% of the cases respectively. Increased levels of cyclin D1 (p = 0.0001) and p21waf1/cip1 protein (p = 0.03) in tumours with mucous differentiation were observed. Overexpression of cyclin D1 was correlated with tumour stage (p = 0.03), the lymph node involvement (p = 0.02), as well as p21waf1/cip1 protein expression (p < 0.0001). Cyclin E was positively correlated with p21waf1/cip1 (p = 0.014), as well as with the cell proliferation as measured by PCNA-labelling index (p = 0.011) and Ki-67 score (p = 0.007). A positive relationship of p21waf1/cip1 expression with the proliferative-associated index Ki-67 was noted (p = 0.005). Downregulation of p27kip1 was observed in 47.4% of the cases and was correlated with downregulation of pRb (p = 0.002) and PCNA score (p = 0.004). The prognostic significance of cyclins D1, E and CDK inhibitors p21waf1/cip1, p27kip1 in determining the risk of recurrence and overall survival with both univariate (long-rang test) and multivariate (Cox regression) methods of analysis showed no statistically significance differences. In conclusion, these findings suggest that, the levels of the cell cycle regulators studied, do not seems to have a prognostic value, in terms of predicting the risk of early recurrence and overall survival. In addition, the interrelationships, probably means their contribution to the regulation of cell growth, through different pathways in colorectal carcinogenesis.

Patterns of expression of cell cycle/apoptosis genes along the spectrum of thyroid carcinoma progression

BACKGROUND

Genetic screening studies suggest that genetic changes underlie progression from well differentiated to anaplastic thyroid cancers. The aim of this study is to determine to what extent cell cycle/apoptosis regulators contribute to cancer progression.

METHODS

Tissue microarrarys (TMAs) were constructed from well-differentiated papillary thyroid carcinoma (WDPTC; n = 41), poorly differentiated thyroid carcinoma (PDTC; n = 43), and anaplastic thyroid carcinoma (ATC; n = 22). TMAs were immunostained for 7 different cell cycle/apoptosis-related genes (p53, Ki-67, bcl-2, mdm-2, cyclin D1, p21, and p27).

RESULTS

p53 (0%, 12%, 32%) and Ki-67 (5%, 49%, 82%) were expressed with increasing frequency, and bcl-2 (68%, 42%, 0%) and p21 (40%, 7%, 0%) with decreasing frequency in WDPTC to PDTC and ATC, respectively (P < .001). Interestingly, mdm-2 (54%, 5%, 0%) showed decreased expression along the progression axis (P < .001). p27 and cyclin D1 were expressed in <15% of cases, with a trend toward decreasing expression from WDPTC to PDTC to ATC.

CONCLUSIONS

These data confirm the presence of increasing genetic complexity with progressive dedifferentiation in thyroid cancer, with aberrant tumor suppressor activity and increased proliferative activity being most prevalent in ATC. The data also confirm the intermediate position of PDTC in the classification scheme of thyroid carcinomas.

Loss of nuclear p21(Cip1/WAF1) during neoplastic progression to metastasis in gamma-irradiated p21 hemizygous mice

p21(Cip1/WAF1) localizes to the nucleus in response to gamma-irradiation induced DNA damage and mediates a G(1) checkpoint arrest. Although gamma-irradiated p21(+/-) mice develop a broad spectrum of tumors, gamma-irradiated p21(-/-) mice develop significantly more metastatic cancers. To evaluate the expression of p21 in tissues prone or resistant to tumorigenesis as a function of gamma-irradiation, and to determine whether phenotypic loss of p21 heterozygosity occurs during tumor progression in p21(+/-) mice, tissues and tumors from gamma-irradiated mice were evaluated immunohistochemically. The percentage of tumors in p21(+/-) mice that were nuclear p21-positive declined with progression to metastasis (p<0.0001). Benign tumors were more often p21-positive and comprised of larger subsets of nuclear p21-positive cells than were malignant tumors of the same histopathological type, while metastatic cancers were nuclear p21-negative (p=0.0003). Even when a primary cancer was comprised of a subset of nuclear p21-positive cells, the metastatic foci of that same cancer were nuclear p21-negative. Mesenchymal tumors, though rare, were more likely metastatic than were epithelial tumors (p=0.0004), and these were invariably nuclear p21-negative. Prepubescent epithelial tissues from which most tumors later originated in mice with reduced p21 gene dosage (i.e., harderian gland, ovary, small intestine, and lung) were p21 expressive within 4 h of gamma-irradiation (p=0.0625), so that p21/Ki67 ratios increased post-gamma-irradiation (p=0.03). In contrast, p21 did not localize to nuclei of cortical thymocytes, a tissue where tumorigenesis was not augmented by reduced p21 gene dosage. Cellular subclones of malignant tumors, especially those of mesenchymal cell origin, which lack nuclear p21 may more readily acquire the genetic alterations of the metastatic phenotype.

Molecular prognostic markers in resectable colorectal liver metastases: A systematic review

BACKGROUND

Determination of prognosis in patients with resectable colorectal liver metastases (CLM) is desirable in order to improve case selection for surgery and tailor adjuvant treatment according to individual recurrence risk. Conventional clinicopathological factors lack the sensitivity to accurately achieve this goal. Consideration of tumour biology and the identification of molecular prognostic markers may allow more accurate risk stratification.

METHOD

This systematic review examines evidence from published manuscripts looking at molecular markers in resectable colorectal liver metastases and their correlation with disease recurrence and survival following hepatectomy.

RESULTS

Studies have yielded promising results in the search for prognostic molecular markers of CLM. Molecular biomarkers from varied aspects of tumour biology have been examined and a number of these, including proliferation indices, telomerase, thymidylate synthase, microvessel density and thrombospondin-1 appear to have prognostic utility in this context. Validation of other markers, notably p53, has been limited by a failure of methodologies to account for their biological complexity.

CONCLUSIONS

A biomarker-based approach may yield significant benefits through informed treatment of resectable metastatic colorectal malignancy. Standardised retrospective analyses are necessary to confirm preliminary findings and identify existing and novel markers for inclusion into prospective studies. Assessment and verification of multiple molecular markers in this manner may allow molecular profiling of metastases and tailoring of therapy according to the biological aggressiveness of individual tumours. The advent of genomic- and proteomic-based technologies will allow the simultaneous analysis of multiple molecular markers and the derivation of disease profiles associated with disease recurrence and poor survival.