Expression of Smad2 and Smad4 in cervical cancer: absent nuclear Smad4 expression correlates with poor survival

Transforming growth factor-β micro-environment mediated immune cell functions in cervical cancer

Propensity to develop cervical cancer (CC) in human papilloma virus (HPV) infected individual could potentially involve the impaired immune functioning. Several stages of HPV surveillance by immune cells in tumor micro-environment (TME) is regulated mainly by transforming growth factor-beta (TGF-β) and is crucial for the establishment of CC. The role of TGF-β in the initiation and progression of CC is very complex and involve different suppressor of mothers against decapentaplegic homolog (SMAD) dependent and SMAD independent signaling mechanism(s). This review summarizes the handling of HPV by immune cells such as T lymphocytes, B lymphocytes, natural killer cells (NK), dendritic cells (DC), monocytes, macrophages, myeloid derived suppressor cells (MDSC) and their regulation by TGF-β. The hijack mechanisms adapted by HPV to evade this surveillance process is discussed. Biomarkers indicating the stages of CC and immune checkpoints that can be targeted for improved outcome are included for immune-based theragnostics. This review also addresses the direct actions of TGF-β on CC cells and tumor/immune cell interactions. Therapies focused on targeting TGF-β using small molecule inhibitors, monoclonal antibodies and TGF-β chimeric antigen receptor (CAR)T cells are collated to understand the current strategies related to TGF-β in the management of CC.

Low Transforming Growth Factor-β Pathway Activity in Cervical Adenocarcinomas

Cervical cancer is the fourth most common cancer in women worldwide. Squamous cell carcinoma (SCC) and adenocarcinoma (AC) are the most common histological types, with AC patients having worse prognosis. Over the last two decades, incidence rates of AC have increased, highlighting the importance of further understanding AC tumorigenesis, and the need to investigate new treatment options. The cytokine TGF-β functions as a tumour suppressor in healthy tissue. However, in tumour cells this suppressive function can be overcome. Therefore there is an increasing interest in using TGF-β inhibitors in the treatment of cancer. Here, we hypothesize that TGF-β plays a different role in SCC and AC. Analysis of RNA-seq data from the TCGA, using a TGF-β response signature, resulted in separate clustering of the two subtypes. We further investigated the expression of TGF-β-signalling related proteins (TβR1/2, SMAD4, pSMAD2, PAI-1, αvβ6 and MMP2/9) in a cohort of 62 AC patients. Low TβR2 and SMAD4 expression was associated with worse survival in AC patients and interestingly, high PAI-1 and αvβ6 expression was also correlated with worse survival. Similar correlations of TβR2, PAI-1 and αvβ6 with clinical parameters were found in previously reported SCC analyses. However, when comparing expression levels between SCC and AC patient samples, pSMAD2, SMAD4, PAI-1 and αvβ6 showed lower expression in AC compared to SCC. Because of the low expression of core TβR1/2, (p-)SMAD2 and SMAD4 proteins and the correlation with worse prognosis, TGF-β pathway most likely leads to tumour inhibitory effects in AC and therefore the use of TGF-β inhibitors would not be recommended. However, given the correlation of PAI-1 and αvβ6 with poor prognosis, the use of TGF- β inhibitors might be of interest in SCC and in the subsets of AC patients with high expression of these TGF-β associated proteins.

HPV-mediated regulation of SMAD4 modulates the DNA damage response in head and neck cancer

Background

Head and Neck cancer (HNC) is a fatal malignancy with poor prognosis. Human Papillomavirus (HPV) infection is becoming the prominent cause of HNC in the western world, and studying the molecular mechanisms underlying its action in cancers is key towards targeted therapy. To replicate, HPV regulates the host DNA damage repair (DDR) pathway. SMAD4 is also involved in the regulation of the DDR machinery and likely plays important role in maintaining cell viability upon genotoxic stress. In this study, we investigated the role of HPV in the upregulation of SMAD4 to control the DDR response and facilitate its lifecycle.

Methods

SMAD4, Rad51 and CHK1 expression was assessed in HPV-positive and HPV-negative HNC using TCGA data, a panel of 14 HNC cell lines and 8 fresh tumour tissue samples from HNC patients. HPV16 expression was modulated by E6/E7 siRNA knock-down or transduction in HPV-positive HNC cell lines and Human Primary keratinocytes respectively. SMAD4 half-life was assessed by cycloheximide treatment in HNC cell lines, together with βTRCP1-dependent SMAD4 ubiquitination. SMAD4 siRNA knock-down was used to determine its role in HPV-mediated regulation of DDR machinery and to assess cisplatin sensitivity in HPV-positive HNC cell lines.

Results

We found that HPV increases SMAD4 expression is both HPV-positive HNC tumours and cell lines, impairing its degradation which is mediated by the E3 ubiquitin ligase βTRCP1. SMAD4 expression highly correlates with the expression of two main players of the DDR pathway, CHK1 and Rad51, which expression is also upregulated by the presence of HPV. In particular, we demonstrate that HPV stabilizes SMAD4 to increase CHK1 and Rad51 expression. In addition, SMAD4-deficient HPV-positive cells have increased sensitivity to cisplatin treatment.

Conclusions

Our results give a clear molecular mechanism at the basis of HPV regulation of the DDR pathway. In particular, we show how HPV stabilizes SMAD4 to promote DDR protein expression, which may be used to facilitate viral replication and HNC onset. Moreover, we found that SMAD4 silencing in HPV-positive HNC cell lines increases sensitivity to cisplatin treatment, suggesting that HPV-positive HNC with low SMAD4 expression may be preferentially susceptible to similar treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02258-9.

Development of an in vitro carcinogenesis model of human papillomavirus-induced cervical adenocarcinoma

Cervical adenocarcinoma (ADC) is the second most common pathological subtype of cervical cancer after squamous cell carcinoma. It accounts for approximately 20% of cervical cancers, and the incidence has increased in the past few decades, particularly among young patients. The persistent infection of high‐risk human papillomavirus (HPV) is responsible for most cervical ADC. However, almost all available in vitro models are designed to study the carcinogenesis of cervical squamous cell carcinoma. To gain better insights into molecular background of ADC, we aimed to establish an in vitro carcinogenesis model of ADC. We previously reported the establishment of an in vitro model for cervical squamous cell carcinoma by introducing defined viral and cellular oncogenes, HPV16 E6 and E7, c‐MYC, and activated RAS to human cervical keratinocytes. In this study, the expression of potential lineage‐specifying factors and/or SMAD4 reduction was introduced in addition to the defined four oncogenes to direct carcinogenesis toward ADC. The cell properties associated with the cell lineage were analyzed in monolayer and organoid cultures and the tumors in mouse xenografts. In the cells expressing Forkhead box A2 (FOXA2), apparent changes in cell properties were observed, such as elevated expression of columnar cell markers and decreased expression of squamous cell markers. Strikingly, the histopathology of tumors expressing FOXA2 resembled cervical ADC, proposing that FOXA2 plays a vital role in dictating the histopathology of cervical cancers.

A narrative review of the relationship between TGF-β signaling and gynecological malignant tumor

Objective

This paper reviews the association between transforming growth factor-β (TGF-β) and its receptor and tumor, focusing on gynecological malignant tumors. we hope to provide more methods to help increase the potential of TGF-β signaling targeted treatment of specific cancers.

Background

The occurrence of a malignant tumor is a complex process of multi-step, multi-gene regulation, and its progression is affected by various components of the tumor cells and/or tumor microenvironment. The occurrence of gynecological diseases not only affect women's health, but also bring some troubles to their normal life. Especially when gynecological malignant tumors occur, the situation is more serious, which will endanger the lives of patients. Due to differences in environmental and economic conditions, not all women have access to assistance and treatment specifically meeting their needs. TGF-β is a multi-potent growth factor that maintains homeostasis in mammals by inhibiting cell growth and promoting apoptosis in vivo. TGF-β signaling is fundamental to inflammatory disease and favors the emergence of tumors, and it also plays an important role in immunosuppression in the tumor microenvironment. In the early stages of the tumor, TGF-β acts as a tumor inhibitor, whereas in advanced tumors, mutations or deletion of the TGF-β signaling core component initiate neogenesis.

Methods

Literatures about TGF-β and gynecological malignant tumor were extensively reviewed to analyze and discuss.

Conclusions

We discussed the role of TGF-β signaling in different types of gynecological tumor cells, thus demonstrating that targeted TGF-β signaling may be an effective tumor treatment strategy.

Immunohistochemical Loss of DPC4 in Tumors With Mucinous Differentiation Arising in or Involving the Gynecologic Tract

DPC4 immunohistochemistry (IHC) is usually part of the work-up of mucinous neoplasms in the ovary where the distinction between an ovarian primary and metastatic pancreaticobiliary adenocarcinoma (PanACa) must be made. Although DPC4 IHC is lost in about 55% (46%-61%) of PanACas and typically retained in most primary ovarian mucinous neoplasms, no study has evaluated the expression of this marker in a large cohort of neoplasms arising in or involving gynecologic (GYN) organs. In this study, we retrospectively analyzed the expression of DPC4 IHC in a total of 251 tumors and lesions related to the GYN tract in which DPC4 IHC stain was performed during the initial pathology evaluation. Of these, 138 were primary GYN tumors and lesions, 31 were metastatic GYN tumors involving non-GYN sites, and 83 were metastatic non-GYN tumors involving the GYN tract. We identified 27 cases with loss of DPC4 IHC expression of which 20 cases met the inclusion criteria (i.e. clinical information was available to determine the site of tumor origin). We observed that loss of DPC4 nuclear expression was most commonly seen in tumors of endocervical origin (n=7), of which 5 were gastric-type cervical adenocarcinomas (GCxACa) and 2 were usual-type cervical adenocarcinomas, either primary or metastatic. This was followed by tumors of the pancreaticobiliary tract (n=5), ovary (n=2), and appendix (n=1). In addition, 1 gastric-type vaginal adenocarcinoma (GVaACa) also showed loss of DPC4. Our findings indicate that in female patients with mucinous neoplasms involving the ovary or other sites, with loss of DPC4 by IHC, and negative pancreaticobiliary imaging, the possibility of an occult GCx/GVaACa, and rarely an ovarian primary must be considered.

Expression of SMAD4 is Retained in Most Gynecologic Tumors with Mucinous Differentiation

SMAD4 is a tumor suppressor gene that plays a role in cancer initiation and progression. A few studies have explored the value of immunohistochemistry for SMAD4 in gynecologic neoplasms, mainly in the ovary. However, literature is sparse when it comes to other sites such as endometrium and cervix, as well as in benign and borderline ovarian mucinous neoplasms. The aim of this study was to assess the expression of SMAD4 in various gynecologic tumors. We selected primary gynecologic tumors comprising a spectrum of neoplasms showing mucinous differentiation. Few cases of metastatic tumors were also included. A total of 103 cases were retrieved, including tumors of ovarian origin (13 mucinous adenocarcinomas, 9 mucinous borderline tumors, 19 mucinous cystadenomas, and 3 mucinous tumors arising from teratomas), 36 of endometrial origin (23 endometrioid adenocarcinomas with mucinous differentiation and 13 mucinous adenocarcinomas), 17 cases of cervical carcinoma (16 of usual type and 1 of gastric type), and 6 metastatic adenocarcinomas to ovary. SMAD4 immunohistochemistry was retained in most primary tumors, except in 3 endocervical adenocarcinomas (2 usual-type, 1 gastric-type) and in one mucinous carcinoma arising from an ovarian teratoma. Of the 6 metastatic cases, 4 showed SMAD4 loss. In summary, retained expression of SMAD4 was seen in 95.8% of primary gynecologic neoplasms. These results can be of utility when dealing with mucinous lesions for which metastatic origin is suspected. Loss of SMAD4 expression virtually excludes primary tumors of endometrial or ovarian origin, but is of less utility when evaluating carcinomas involving the cervix.

SMAD2 rs4940086 heterozygosity increases the risk of cervical cancer development among the women in Bangladesh

SMAD2 is a critical signal transducer molecule in the TGFβ- SMAD pathway which is also known for its tumor suppressor role. Genetic variations in SMAD2 render cells insensitive to its anti-proliferative signals leading to tumor formation. In this study, we demonstrate the impact of single nucleotide polymorphisms (SNPs) of SMAD2 (rs4940086 and rs8085335) on cervical cancer risk development in Bangladeshi population. 132 cervical cancer patients and 98 control volunteers were enrolled in the study and genotyped utilizing polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The association between cervical cancer susceptibility and the chosen SNPs were evaluated through multiple logistic regression. SMAD2 rs4940086 heterozygous genotype (T/C) was associated with a 3.89 times higher risk of cervical cancer development (P = 0.001, AOR 3.89, 95% CI 1.777-8.513). The T/C and C/C genotypes in combination also significantly elevated cervical cancer risk (P = 0.035, AOR 1.876, 95% CI 1.047-3.364). Urban cancer patients had a significantly higher chance of carrying the rs4940086 polymorphism as compared to rural cancer patients (P = 0.045, OR 2.59 95% CI 1.02-6.59). SMAD2 rs8085335 heterozygous variant (A/G) demonstrated modest effects in increasing cervical cancer susceptibility (P = 0.594, AOR 1.247, 95% CI 0.554-2.809). Our results suggest that polymorphic variations in SMAD2, particularly rs4940086, can potentially elevate cervical cancer susceptibility in Bangladeshi women.

Whole-exome sequencing of cervical carcinomas identifies activating ERBB2 and PIK3CA mutations as targets for combination therapy

The prognosis of advanced/recurrent cervical cancer patients remains poor. We analyzed 54 fresh-frozen and 15 primary cervical cancer cell lines, along with matched-normal DNA, by whole-exome sequencing (WES), most of which harboring Human-Papillomavirus-type-16/18. We found recurrent somatic missense mutations in 22 genes (including PIK3CA, ERBB2, and GNAS) and a widespread APOBEC cytidine deaminase mutagenesis pattern (TCW motif) in both adenocarcinoma (ACC) and squamous cell carcinomas (SCCs). Somatic copy number variants (CNVs) identified 12 copy number gains and 40 losses, occurring more often than expected by chance, with the most frequent events in pathways similar to those found from analysis of single nucleotide variants (SNVs), including the ERBB2/PI3K/AKT/mTOR, apoptosis, chromatin remodeling, and cell cycle. To validate specific SNVs as targets, we took advantage of primary cervical tumor cell lines and xenografts to preclinically evaluate the activity of pan-HER (afatinib and neratinib) and PIK3CA (copanlisib) inhibitors, alone and in combination, against tumors harboring alterations in the ERBB2/PI3K/AKT/mTOR pathway (71%). Tumors harboring ERBB2 (5.8%) domain mutations were significantly more sensitive to single agents afatinib or neratinib when compared to wild-type tumors in preclinical in vitro and in vivo models (P = 0.001). In contrast, pan-HER and PIK3CA inhibitors demonstrated limited in vitro activity and were only transiently effective in controlling in vivo growth of PIK3CA-mutated cervical cancer xenografts. Importantly, combinations of copanlisib and neratinib were highly synergistic, inducing long-lasting regression of tumors harboring alterations in the ERBB2/PI3K/AKT/mTOR pathway. These findings define the genetic landscape of cervical cancer, suggesting that a large subset of cervical tumors might benefit from existing ERBB2/PIK3CA/AKT/mTOR-targeted drugs.

Frequent loss of heterozygosity of SMAD4 locus and prognostic impacts of SMAD4 immunohistochemistry in gastric adenocarcinoma with enteroblastic differentiation

Gastric adenocarcinoma with enteroblastic differentiation (GAED) is a rare variant of gastric adenocarcinoma. Clinicopathologically, GAED is known to be aggressive and is characterized by frequent vascular invasion, lymphatic invasion, and liver metastasis even in early stages. SMAD4 was identified as a frequently deleted gene in GAED by copy number variation analysis in our previous next-generation sequencing study; therefore, we examined the clinicopathological impacts of SMAD4 in 51 cases of GAEDs (early: 17, advanced: 34). We performed Sanger sequencing for SMAD4 mutations and loss of heterozygosity (LOH) analysis of the SMAD4 locus, in addition to immunohistochemistry for SMAD4, to determine its clinicopathological correlations and impacts on survival. The frequency of LOH at the SMAD4 locus was 45.1%, and it was significantly higher in GAED compared to in conventional gastric adenocarcinoma. SMAD4 mutations were not found in any case. Reduced SMAD4 expression was found in 60.8% of cases; it was significantly correlated with advanced stages and lymph node metastasis and showed trends of larger tumor size and lymphatic invasion. Reduced SMAD4 expression in metastatic lymph nodes was found in 21 of 36 cases. Survival analysis revealed that reduced SMAD4 expression significantly affected the patient's overall survival (OS) and recurrence-free survival (RFS), although multivariate analysis showed that only liver metastasis and lymphatic infiltration (Ly+) were independent prognostic factors for OS and RFS. The SMAD4 locus is one of the susceptibility genes in this tumor, although SMAD4 mutation was not detected. Furthermore, the inactivation of SMAD4 appeared to contribute to the aggressiveness of GAED.

Oncogenic role of microRNA-532-5p in human colorectal cancer via targeting of the 5'UTR of RUNX3

Previous studies have demonstrated that microRNAs (miRs) are involved in the carcinogenesis of colorectal cancer (CRC). To the best of our knowledge, the function and regulatory role of miR-532-5p in human CRC remains unknown. The aim of the present study was to determine the role and regulation of miR-532-5p in CRC. Using the reverse transcription-quantitative polymerase chain reaction, it was demonstrated that miR-532-5p was upregulated, whereas runt-related transcription factor 3 (RUNX3) was downregulated in CRC tissues. The upregulated miR-532-5p was associated with the downregulated RUNX3. Furthermore, the two biomarkers were associated with numerous clinicopathological characteristics of CRC, including tumor stage, lymph node involvement, differentiation, vessel invasion and tumor recurrence. The in vitro luciferase reporter assay demonstrated that transfection with miR-532-5p mimic markedly downregulated the RUNX3 mRNA and protein levels, via specific binding to the 5'-untranslated region of RUNX3 in human HT-29 CRC cells. In addition, an MTT assay and a colony formation assay demonstrated that miR-532-5p overexpression led to increased tumor cell viability and colony formation ability of HT-29 cells. In conclusion, the results of the present study indicate that miR-532-5p may function as an oncogenic miRNA by promoting cell growth in human CRC cells, and such promotion is associated with the targeted inhibition of RUNX3.

The expression and underlying angiogenesis effect of DPC4 and VEGF on the progression of cervical carcinoma

The present study aimed to investigate the expression and roles of deleted in pancreatic carcinoma locus 4 (DPC4) and vascular endothelial growth factor (VEGF) in the development of cervical carcinoma. A total of 115 patients aged between 25 and 60 years were involved, including 19 cervical inflammation, 35 cervical intraepithelial neoplasia (CIN), and 61 cervical squamous-cell carcinoma (CSCC). The protein expression rates of DPC4 and VEGF in all samples were detected using immunohistochemistry. The protein levels of DPC4 and VEGF in CSCC samples were measured using ELISA. Microvessel density (MVD) of each CSCC sample was measured according to the Winder method. Association analysis between DPC4, VEGF and thrombospondin-1 (TSP-1) was conducted using Spearman's correlations. The negative expression rate of DPC4 [DPC4 (-)] and positive expression rate of VEGF [VEGF (+)] of the CSCC group were significantly higher compared with that in the cervical inflammation and CIN groups (P<0.05). In the CSCC group, the protein level of DPC4 decreased, while the VEGF level increased significantly compared with the healthy control group (P<0.05). The MVD in the DPC4 (-), VEGF (+) and TSP-1 (-) groups was significantly increased compared with that of the DPC4 (+), VEGF (-), and TSP-1 (+) groups (P<0.05). The expression of DPC4 was negatively associated with VEGF and TSP-1 (P<0.01). These results suggest that DPC4, VEGF and TSP-1 are involved in the carcinogenesis of cervical carcinoma by inducing angiogenesis. In addition, the loss of DPC4 induces angiogenesis through increasing VEGF. Thus, VEGF may be a target gene regulated by DPC4.

Down-Regulation of MicroRNA-210 Confers Sensitivity towards 1'S-1'-Acetoxychavicol Acetate (ACA) in Cervical Cancer Cells by Targeting SMAD4

MicroRNAs (miRNAs) are short non-coding RNAs that regulate genes posttranscriptionally. Past studies have reported that miR-210 is up-regulated in many cancers including cervical cancer, and plays a pleiotropic role in carcinogenesis. However, its role in regulating response towards anti-cancer agents has not been fully elucidated. We have previously reported that the natural compound 1'S-1'-acetoxychavicol acetate (ACA) is able to induce cytotoxicity in various cancer cells including cervical cancer cells. Hence, this study aims to investigate the mechanistic role of miR-210 in regulating response towards ACA in cervical cancer cells. In the present study, we found that ACA down-regulated miR-210 expression in cervical cancer cells, and suppression of miR-210 expression enhanced sensitivity towards ACA by inhibiting cell proliferation and promoting apoptosis. Western blot analysis showed increased expression of mothers against decapentaplegic homolog 4 (SMAD4), which was predicted as a target of miR-210 by target prediction programs, following treatment with ACA. Luciferase reporter assay confirmed that miR-210 binds to sequences in 3'UTR of SMAD4. Furthermore, decreased in SMAD4 protein expression was observed when miR-210 was overexpressed. Conversely, SMAD4 protein expression increased when miR-210 expression was suppressed. Lastly, we demonstrated that overexpression of SMAD4 augmented the anti-proliferative and apoptosis-inducing effects of ACA. Taken together, our results demonstrated that down-regulation of miR-210 conferred sensitivity towards ACA in cervical cancer cells by targeting SMAD4. These findings suggest that combination of miRNAs and natural compounds could provide new strategies in treating cervical cancer.

De-repression of the RAC activator ELMO1 in cancer stem cells drives progression of TGFβ-deficient squamous cell carcinoma from transition zones

Squamous cell carcinomas occurring at transition zones are highly malignant tumors with poor prognosis. The identity of the cell population and the signaling pathways involved in the progression of transition zone squamous cell carcinoma are poorly understood, hence representing limited options for targeted therapies. Here, we identify a highly tumorigenic cancer stem cell population in a mouse model of transitional epithelial carcinoma and uncover a novel mechanism by which loss of TGFβ receptor II (Tgfbr2) mediates invasion and metastasis through de-repression of ELMO1, a RAC-activating guanine exchange factor, specifically in cancer stem cells of transition zone tumors. We identify ELMO1 as a novel target of TGFβ signaling and show that restoration of Tgfbr2 results in a complete block of ELMO1 in vivo. Knocking down Elmo1 impairs metastasis of carcinoma cells to the lung, thereby providing insights into the mechanisms of progression of Tgfbr2-deficient invasive transition zone squamous cell carcinoma.

In silico pathway analysis in cervical carcinoma reveals potential new targets for treatment

An in silico pathway analysis was performed in order to improve current knowledge on the molecular drivers of cervical cancer and detect potential targets for treatment. Three publicly available Affymetrix gene expression data-sets (GSE5787, GSE7803, GSE9750) were retrieved, vouching for a total of 9 cervical cancer cell lines (CCCLs), 39 normal cervical samples, 7 CIN3 samples and 111 cervical cancer samples (CCSs). Predication analysis of microarrays was performed in the Affymetrix sets to identify cervical cancer biomarkers. To select cancer cell-specific genes the CCSs were compared to the CCCLs. Validated genes were submitted to a gene set enrichment analysis (GSEA) and Expression2Kinases (E2K). In the CCSs a total of 1,547 probe sets were identified that were overexpressed (FDR < 0.1). Comparing to CCCLs 560 probe sets (481 unique genes) had a cancer cell-specific expression profile, and 315 of these genes (65%) were validated. GSEA identified 5 cancer hallmarks enriched in CCSs (P < 0.01 and FDR < 0.25) showing that deregulation of the cell cycle is a major component of cervical cancer biology. E2K identified a protein-protein interaction (PPI) network of 162 nodes (including 20 drugable kinases) and 1626 edges. This PPI-network consists of 5 signaling modules associated with MYC signaling (Module 1), cell cycle deregulation (Module 2), TGFβ-signaling (Module 3), MAPK signaling (Module 4) and chromatin modeling (Module 5). Potential targets for treatment which could be identified were CDK1, CDK2, ABL1, ATM, AKT1, MAPK1, MAPK3 among others. The present study identified important driver pathways in cervical carcinogenesis which should be assessed for their potential therapeutic drugability.

Transforming growth factor-β1 in carcinogenesis, progression, and therapy in cervical cancer

Transforming growth factor β1 (TGF-β1) is a multifunctional cytokine that plays important roles in cervical tumor formation, invasion, progression, and metastasis. TGF-β1 functions as a tumor inhibitor in precancerous lesions and early stage cancers of cervix whereas as a tumor promoter in later stage. This switch from a tumor inhibitor to a tumor promoter might be due to various alterations in TGF-β signaling pathway, such as mutations or loss of expression of TGF-β receptors and SMAD proteins. Additionally, the oncoproteins of human papillomaviruses have been shown to stimulate TGF-β1 expression, which in turn suppresses host immune surveillance. Thus, in addition to driving tumor cell migration and metastasis, TGF-β1 is believed to play a key role in promoting human papillomavirus infection by weakening host immune defense. In this article, we will discuss the role of TGF-β1 in the expression, carcinogenesis, progression, and therapy in cervical cancers. A better understanding of this cytokine in cervical carcinogenesis is essential for critical evaluation of this cytokine as a potential prognostic marker and therapeutic target.

Prognostic Value of SMAD4 in Pancreatic Cancer: A Meta-Analysis

PURPOSE: The prognostic value of SMAD4 in pancreatic cancer has been evaluated in several studies. However, the conclusions remain controversial. Therefore, we aimed to evaluate the association between SMAD4 expression and the outcome of pancreatic cancer patients by performing a meta-analysis. METHODS: We systematically searched for relevant studies evaluating the relationship between SMAD4 expression and the outcome of pancreatic cancer patients until May 2015. A meta-analysis was performed using STATA 12.0, and pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were used to estimate the strength of the association between SMAD4 expression and the prognosis of pancreatic cancer patients. RESULTS: The analysis included 1762 patients from 14 studies, with 1401 patients from 11 studies and 927 patients from 8 studies included in the univariate and multivariate analyses, respectively. Loss of SMAD4 expression was found to be significantly correlated with poor overall survival, with the combined HR (95% CI) of 1.20 (1.03-1.40). After adjusting for potential confounders using the Cox regression model, the pooled HR (95% CI) was 1.88 (1.31-2.70). In subgroup analysis, study region, number of patients, follow-up duration, and cutoff value were found to affect the significance of the association between loss of SMAD4 expression and poor prognosis. In addition, there was no evidence of publication bias, as suggested by Begg’s and Egger’s test. CONCLUSIONS: Loss of SMAD4 was associated with poor survival and was a negative prognostic indicator in patients with pancreatic cancer.

miR-212/132 downregulates SMAD2 expression to suppress the G1/S phase transition of the cell cycle and the epithelial to mesenchymal transition in cervical cancer cells

MicroRNAs (miRNAs), a class of small noncoding RNAs that regulate target gene expression, play an important role in cancer initiation, progression, and metastasis. However, the role of many miRNAs in cervical cancer is not fully understood. In this study, we found that miR-212 and miR-132 from the same gene cluster are downregulated in human cervical cancer tissues when compared with adjacent noncancerous tissues. The overexpression of miR-212/132 not only led to a delay in the G1/S phase transition and repressed cell proliferation but also resulted in an increase in E-cadherin expression and a decrease in vimentin, suppressing the epithelial to mesenchymal transition and migration and invasion in cervical cancer cells. Subsequently, SMAD2 was identified as a common target of miR-212/132 and was found to be negatively regulated by miR-212/132 at the mRNA and protein levels. Furthermore, SMAD2 silencing led to the same effect on cervical cancer cells as miR-212/132 overexpression. Importantly, SMAD2 overexpression partially reversed the cellular phenotypes induced by miR-212/132 overexpression. In conclusion, our study indicated that miR-212/132 functions as tumor suppressor by targeting SMAD2 in cervical cancer.

Meta-analysis of the prognostic value of smad4 immunohistochemistry in various cancers

Background

Accumulating evidence indicates that Smad4 (DPC4) plays a fundamental role in the development and prognosis of several types of cancer. The objective of this study was to conduct a meta-analysis to evaluate whether the loss of Smad4 staining could serve as a prognostic marker.

Methods

A comprehensive meta-analysis was conducted using major useful databases to determine the relationship between the immunohistochemical detection of Smad4 and the survival of patients with various cancers. We used hazard ratios (HRs) with 95% confidence interval (CIs) as the effect estimation to evaluate the association of Smad4 with overall survival (OS), cancer-specific survival (CSS) or recurrence-free survival (RFS). The relationship between the clinical characteristics of patients and Smad4 was also evaluated using the odds ratio (OR).

Results

A total of 7570 patients from 26 studies were included in the analysis. The pooled results showed that loss of Smad4 staining was a negative predictor of OS with an HR of 1.97 (95% CI: 1.55–2.51; P_{heterogeneity}<0.001) and CSS/RFS (HR = 1.81; 95% CI: 1.30–2.54; P_{heterogeneity}<0.001). In addition, loss of Smad4 staining was more likely to be found in older (OR = 1.69, 95% CI: 1.09–2.61; P_{heterogeneity} = 0.648) colorectal cancer patients with a late tumor stage (OR = 2.31, 95% CI: 1.71–3.10; P_{heterogeneity} = 0.218) and in gastric cancer patients with lymph node metastasis (OR = 2.11, 95% CI: 1.03–4.34; P_{heterogeneity} = 0.038).

Conclusion

Based on these results, our meta-analysis provided evidence that loss of Smad4 staining could act as an unfavorable biomarker in the prognosis of various cancers and should be used as a powerful tool in future clinical trials.

microRNA expression pattern modulates temozolomide response in GBM tumors with cancer stem cells

Temozolomide (TMZ) is widely used to treat glioblastoma multiforme (GBM). Although the MGMT gene methylation status is postulated to correlate with TMZ response, some patients with a methylated MGMT gene still do not benefit from TMZ therapy. Cancer stem cells (CSCs) may be one of the causes of therapeutic resistance, but the molecular mechanism underlying this resistance is unclear. microRNA (miRNA) deregulation has been recognized as another chemoresistance modulating mechanism. Thus, we aimed to evaluate the miRNA expression patterns associated with chemoresistance that is dependent on the CSC status in GBM tumors to identify therapeutic biomarkers. CSCs were identified in 5 of 20 patients' tumor tissues using magnetic separation. CSC (+) tumors displayed a significant induction of CpG island methylation in the MGMT gene promoter (p = 0.009). Using real-time reverse transcription polymerase chain reaction (qRT-PCR), 9 miRNAs related to GBM (mir-181b, miR-153, miR-137, miR-145, miR-10a, miR-10b, let-7d, miR-9, and miR-455-3p), which are associated with cell cycle and invasion was analyzed in tumor samples. Low miR-181b and high miR-455-3p expression levels were detected (p = 0.053, p = 0.004; respectively) in CSC (+) tumors. Analysis revealed a significant correlation between miR-455-3p expression and Smad2 protein levels as analyzed by immunohistochemistry in CSC (+) tumors (p = 0.002). Thus, miR-455-3p may be involved in TMZ resistance in MGMT methylated CSC (+) GBM patients. Further studies and evaluations are required, but this miRNA may provide novel therapeutic molecular targets for GBM treatment and new directions for the development of anticancer drugs.

Partial loss of Smad signaling during in vitro progression of HPV16-immortalized human keratinocytes

Background

Disruption of the transforming growth factor-beta (TGF-β) signaling pathway is observed in many cancers, including cervical cancer, resulting in TGF-β resistance. While normal human keratinocytes (HKc) and human papillomavirus type 16-immortalized HKc (HKc/HPV16) are sensitive to the growth inhibitory effects of TGF-β, HKc/HPV16 develop resistance to TGF-β1 as they progress in vitro to a differentiation resistant phenotype (HKc/DR). The loss of sensitivity to the antiproliferative effects of TGF-β1 in HKc/DR is due, at least partially, to decreased expression of the TGF-β receptor type I. In the present study, we explored in detail whether alterations in Smad protein levels, Smad phosphorylation, or nuclear localization of Smads in response to TGF-β could contribute to the development of TGF-β resistance during in vitro progression of HKc/HPV16, and whether TGF-β induction of a Smad-responsive reporter gene was altered in HKc/DR.

Methods

Western blot analysis was used to assess Smad protein levels. In order to study Smad nuclear localization we performed indirect immunofluorescence. In addition, we determined Smad-mediated TGF-β signaling using a luciferase reporter construct.

Results

We did not find a decrease in protein levels of Smad2, Smad3 or Smad4, or an increase in the inhibitory Smad7 that paralleled the loss of sensitivity to the growth inhibitory effects of TGF-β1 observed in HKc/DR. However, we found diminished Smad2 phosphorylation, and delayed nuclear Smad3 localization in response to TGF-β1 in HKc/DR, compared to normal HKc and TGF-β sensitive HKc/HPV16. In addition, we determined that TGF-β1 induction of a Smad responsive promoter is reduced by about 50% in HKc/DR, compared to HKc/HPV16.

Conclusions

These results demonstrate that alterations in Smad protein levels are not associated with the loss of response to the antiproliferative effects of TGF-β in HKc/DR, but that diminished and delayed Smad phosphorylation and nuclear localization, and decreased Smad signaling occur in response to TGF-β in HKc/DR.

Nip the HPV encoded evil in the cancer bud: HPV reshapes TRAILs and signaling landscapes

HPV encoded proteins can elicit ectopic protein–protein interactions that re-wire signaling pathways, in a mode that promotes malignancy. Moreover, accumulating data related to HPV is now providing compelling substantiation of a central role played by HPV in escaping immunosurveillance and impairment of apoptotic response. What emerges is an intricate network of Wnt, TGF, Notch signaling cascades that forms higher-order ligand–receptor complexes routing downstream signaling in HPV infected cells. These HPV infected cells are regulated both extracellularly by ligand receptor axis and intracellularly by HPV encoded proteins and impair TRAIL mediated apoptosis. We divide this review into different sections addressing how linear signaling pathways integrate to facilitate carcinogenesis and compounds that directly or indirectly reverse these aberrant interactions offer new possibilities for therapy in cancer. Although HPV encoded proteins mediated misrepresentation of pathways is difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can target dysregulated pathways in HPV infected cervical cancer cells, thus setting the stage for preclinical models and clinical trials.

Nuclear expression of Smad proteins and its prognostic significance in clear cell renal cell carcinoma

Smad2, Smad3, and Smad4 are components of the transforming growth factor β signaling pathway associated with tumorigenesis. The expression of these proteins is associated with tumor progression and prognosis of many cancers. This study aimed to evaluate the nuclear expression of Smad2, Smad3, and Smad4 in clear cell renal cell carcinoma and to assess the clinical significance and prognostic value of their expression patterns. The nuclear expression levels of Smads were evaluated in 637 cases of clear cell renal cell carcinomas using immunohistochemistry. To determine the statistical significance of Smad expression in clear cell renal cell carcinoma, each of the cases were divided into 2 groups (low and high expression groups) according to the extent of nuclear staining. Nuclear expressions of Smad3 and Smad4 were inversely correlated with the patient's age, the nuclear grade, the tumor size, and the pTNM stage. The Smad3-low and Smad4-low groups showed significantly shorter cancer-specific and progression-free survival times. Furthermore, multivariate analysis showed that both Smad3 and Smad4 were independent predictors for progression-free survival (P = .008 and P = .022, respectively). However, Smad2 expression was not related to clinicopathologic parameters and patients' survival. These results suggest that nuclear expressions of Smad3 and Smad4 were related to prognosis of clear cell renal cell carcinoma patients and may serve as novel prognostic markers in clear cell renal cell carcinoma patients.

A novel method to analyze nucleocytoplasmic transport in vivo by using short peptide tags

Regulated nucleocytoplasmic transport is of vital importance for maintaining the physiology of the cell, and disturbed nucleocytoplasmic shuttling of certain proteins has been found in a variety of diseases including cancer. The most frequently used procedure to analyze those processes is to fuse the protein of interest to a fluorescent protein such as GFP (green fluorescent protein)--a technique that is prone to impair normal protein function and subcellular localization. We report a novel approach to monitor nucleocytoplasmic transport processes in vivo by combining short TetR inducing peptide tags (TIP) with a TetR-controlled reporter gene in a human cell line. The technology is exemplified by demonstrating nucleocytoplasmic shuttling of the glucocorticoid receptor and activity of two further TIP fusions to cancer-related proteins. The technology presented provides the basis for efficient screening systems to isolate compounds altering the nucleocytoplasmic distribution of a protein of interest.

HLA-E expression in cervical adenocarcinomas: association with improved long-term survival

BACKGROUND

Cervical cancer is the third most common cancer in women worldwide. The most common histopathological subtype is cervical squamous cell carcinoma (SCC, 75-80%), followed by adenocarcinoma (AC) and adenosquamous carcinoma (ASC; together 15-20%). Rising incidence rates of AC have been observed relative and absolute to SCC and evidence is accumulating that cervical AC is a distinct clinical entity. Cervical SCC, ASC, and AC are caused by a persistent infection with high-risk human papillomavirus (HPV) and failed control of the immune system plays a pivotal role in the carcinogenesis of all three histopathological subtypes. Human leukocyte antigen E (HLA-E), a non-classical HLA class Ib molecule, plays an important role in immune surveillance and immune escape of virally infected cells. In this study we investigated HLA-E expression in three well-defined cohorts of cervical AC, ASC, and SCC patients, and determined whether HLA-E expression was associated with histopathological parameters and patient survival.

METHODS AND RESULTS

HLA-E expression was assessed by immunohistochemistry on formalin-fixed, paraffin-embedded tissue sections of 79 SCC, 38 ASC, and 75 AC patients. All patients included were International Federation of Gynaecology and Obstetrics stage I-II and underwent radical hysterectomy with lymphadenectomy as primary treatment. Significant differences between the histopathological subgroups were detected for age distribution, HPV positivity, HPV type distribution, tumour size, tumour infiltration depth, lymph-vascular space invasion, and adjuvant radiotherapy. High expression of HLA-E was found in 107/192 (56%) cervical carcinomas, with significantly more overexpression in cervical AC compared to SCC and ASC (37/79 SCC, 18/38 ASC, and 52/75 AC; P = 0.010). High HLA-E expression in cervical AC was associated with favourable long term disease-specific and recurrence-free survival (P = 0.005 and P = 0.001, respectively).

CONCLUSION

High expression of HLA-E occurred in the majority of all histopathological subtypes of cervical cancer; especially in cervical AC. High HLA-E expression in cervical AC was associated with improved patient survival. This study also highlights the importance of careful evaluation of cervical carcinomas to distinguish histopathological subtypes. In the future, insight into the biological behaviour and distinct molecular carcinogenetic processes of the AC, ASC, and SCC subtypes may contribute to the development of more tumour-specific treatment strategies.

Contribution of retinoblastoma LOH and the p53 Arg/Pro polymorphism to cervical cancer

Epidemiological studies indicate that infections by certain types of human papillomaviruses (HPVs) are causally linked to the development of cervical cancer. It is also known that HPV infections alone do not cause progression to cervical cancer, as additional genetic changes such as loss of distinct chromosomal regions, inactivation of tumor-suppressor genes and activation of oncogenes must also occur in order for malignant transformation to take place. In the present study, 78 patients diagnosed with cervical cancer and 36 cervical cancer-free cases (control) were analyzed for high-risk HPV genotypes (16 and 18) by polymerase chain reaction (PCR). Loss of heterozygosity (LOH) of the retinoblastoma gene (Rb) at two polymorphic intronic sites (intron 1 and 17) and the p53 polymorphism in codon 72 were detected by RFLP and allele-specific PCR, respectively. HPV 16 and 18 were found at frequencies of 93.6 and 8.3% in the cervical cancer and control samples, respectively. LOH was detected in 63% of patients in intron 1 and/or intron 17. p53 allele frequency for Arg/Arg was 43.6% (34/78), for Arg/Pro 37.2% (29/78) and for Pro/Pro 19.2% (15/78). The relative risk (RR) of LOH and Arg/Arg alone was 1.7 and 1.1, respectively, while the combined RR for Rb LOH and p53 Arg/Arg was 2.5. The present study showed a significant association of the chromosomal allelic loss of Rb in Sudanese cervical cancer patients, while no such association was observed with other parameters, such as clinical stage and degree of differentiation; hence, it cannot be a determinant of tumor behavior in cervical carcinoma. Although the p53 arginine allele is itself an important risk factor for cervical cancer, the combined risk with LOH of Rb, which appears to be greater, might indicate a possible epistatic effect of the two genes/polymorphisms.

SLC5A8 nuclear translocation and loss of expression are associated with poor outcome in pancreatic ductal adenocarcinoma

OBJECTIVES

This study aimed to assess the role of SLC5A8 expression in the survival of pancreatic cancer.

METHODS

We determined SLC5A8 expression in pancreatic ductal adenocarcinoma and adjacent non-neoplastic pancreas (NNP) obtained from 110 patients who underwent pancreatectomy. Formalin-fixed paraffin-embedded core sections in a tissue microarray were immunostained using polyclonal anti-SLC5A8 antibody, and a semiquantitative measure of SLC5A8 expression was determined.

RESULTS

SLC5A8 expression was low in 56% (62/110) of pancreatic cancers as compared to NNP that had low expression in only 9% (10/107) of specimens (P < 0.0001). All cells expressing SLC5A8 did so in the cytoplasm, whether they are neoplastic or not. Nuclear expression of SLC5A8 occurred in 38% (42/110) of cancers, but it was uncommon in NNP (7%, 8/107) (P < 0.0001). Kaplan-Meier estimates showed that survival in patients whose cancers had low SLC5A8 expression, and/or nuclear expression, was significantly worse than in patients whose cancers had none of these abnormalities (P = 0.02). For the 88 patients whose cancers had abnormal SLC5A8 expression, median survival was 1.4 years, as compared to 3.9 years in patients whose cancers both expressed high levels of SLC5A8 and lacked nuclear expression.

CONCLUSIONS

SLC5A8 nuclear translocation and loss of expression are associated with poor outcome in pancreatic ductal adenocarcinoma.

Emerging promise of epigenetics and DNA methylation for the diagnosis and management of women's cancers

Over the last two decades, survival rates from women's cancers (breast, ovarian, endometrial and cervical cancer) have all but modestly improved despite huge efforts from both research and clinical communities. In parallel with this, the field of epigenetics has grown from its infancy into a promising scientific discipline. In particular, DNA methylation analysis has been adopted by oncologists in an attempt to better understand and manage cancer. Now that the epigenetic technological base has caught up, the potential of methylation markers in cancer research is finally being realized. In this review, we present the current status of epigenetic research into women's cancers with a main focus on DNA methylation analysis. We provide an overview of technological development, current markers of risk prediction, early detection, diagnosis, prognosis and response to treatment, and highlight the progression of epigenetic therapies. Finally, we comment on the potential impact of epigenetic analyses on the future of women's health.

Expression and clinical significance of the transforming growth factor-β signalling pathway in endometrial cancer

AIMS

To evaluate the components of the transforming growth factor (TGF)-β-Smad signalling pathway in human endometrial cancer (EC).

METHODS AND RESULTS

TGF-β1, TGF-β receptor type I, TGF-β receptor type II, Smad2, Smad3, Smad4, Skil and Disabled-2 (DAB2) mRNA levels were determined by reverse transcriptase polymerase chain reaction on EC cell lines and in 70 EC tissues. Immunohistochemistry for Skil and DAB2 antibodies was performed on 362 EC cases. Decreased mRNA levels of all eight components of the TGF-β pathway tested were found in the majority of 70 cases. For DAB2, the mRNA level was correlated with protein expression level (P = 0.04). The Skil mRNA level was associated with tumour stage (P = 0.03), and the Smad2/3/4 mRNA level with tumour grade (P = 0.03, P = 0.02, and P = 0.00, respectively). The Smad4 mRNA level was also associated with tumour size (P = 0.05), subtype (P = 0.04), and disease-free survival (DFS) (P = 0.05). The TGF-β1 mRNA level was associated with DFS (P = 0.04). Finally, tumours with positive Skil protein expression had a shorter recurrence time, whereas, those with positive DAB2 protein expression had a longer recurrence time.

CONCLUSIONS

Down-regulation of the TGF-β-Smad signalling pathway might be responsible for the pathogenesis of human EC, and some of its components appeared to be prognostic factors. Exploration of future therapy targeting the TGF-β-Smad pathway is warranted in EC.

Discovery of SMAD4 promoters, transcription factor binding sites and deletions in juvenile polyposis patients

Inactivation of SMAD4 has been linked to several cancers and germline mutations cause juvenile polyposis (JP). We set out to identify the promoter(s) of SMAD4, evaluate their activity in cell lines and define possible transcription factor binding sites (TFBS). 5′-rapid amplification of cDNA ends (5′-RACE) and computational analyses were used to identify candidate promoters and corresponding TFBS and the activity of each was assessed by luciferase vectors in different cell lines. TFBS were disrupted by site-directed mutagenesis (SDM) to evaluate the effect on promoter activity. Four promoters were identified, two of which had significant activity in several cell lines, while two others had minimal activity. In silico analysis revealed multiple potentially important TFBS for each promoter. One promoter was deleted in the germline of two JP patients and SDM of several sites led to significant reduction in promoter activity. No mutations were found by sequencing this promoter in 65 JP probands. The predicted TFBS profiles for each of the four promoters shared few transcription factors in common, but were conserved across several species. The elucidation of these promoters and identification of TFBS has important implications for future studies in sporadic tumors from multiple sites, and in JP patients.

Involvement of the TGF-beta and beta-catenin pathways in pelvic lymph node metastasis in early-stage cervical cancer

PURPOSE

Presence of pelvic lymph node metastases is the main prognostic factor in early-stage cervical cancer patients, primarily treated with surgery. Aim of this study was to identify cellular tumor pathways associated with pelvic lymph node metastasis in early-stage cervical cancer.

EXPERIMENTAL DESIGN

Gene expression profiles (Affymetrix U133 plus 2.0) of 20 patients with negative (N(0)) and 19 with positive lymph nodes (N(+)), were compared with gene sets that represent all 285 presently available pathway signatures. Validation immunostaining of tumors of 274 consecutive early-stage cervical cancer patients was performed for representatives of the identified pathways.

RESULTS

Analysis of 285 pathways resulted in identification of five pathways (TGF-β, NFAT, ALK, BAD, and PAR1) that were dysregulated in the N(0), and two pathways (β-catenin and Glycosphingolipid Biosynthesis Neo Lactoseries) in the N(+) group. Class comparison analysis revealed that five of 149 genes that were most significantly differentially expressed between N(0) and N(+) tumors (P < 0.001) were involved in β-catenin signaling (TCF4, CTNNAL1, CTNND1/p120, DKK3, and WNT5a). Immunohistochemical validation of two well-known cellular tumor pathways (TGF-β and β-catenin) confirmed that the TGF-β pathway (positivity of Smad4) was related to N(0) (OR: 0.20, 95% CI: 0.06-0.66) and the β-catenin pathway (p120 positivity) to N(+) (OR: 1.79, 95%CI: 1.05-3.05).

CONCLUSIONS

Our study provides new, validated insights in the molecular mechanism of lymph node metastasis in cervical cancer. Pathway analysis of the microarray expression profile suggested that the TGF-β and p120-associated noncanonical β-catenin pathways are important in pelvic lymph node metastasis in early-stage cervical cancer.

Expression of Smad and its signalling cascade in osteosarcoma

AIMS

Smad signalling is important for inducing the expression of cell cycle inhibitors such as p21/WAF1, thereby facilitating transforming growth factor (TGF)-beta mediated inhibition of cell growth. The role and clinical implications of Smad signalling in osteosarcoma remain unclear.

METHODS

We assessed the immunohistochemical expression profiles of Smad2, P-Smad2, Smad4, and p21/WAF1 proteins in 34 cases of osteosarcoma. We also investigated whether the expression of these proteins was correlated with clinicopathological parameters.

RESULTS

The p21/WAF1 expression showed a significant relationship with tumour extension (p = 0.018). Smad4 expression was significantly correlated with Smad2 (p = 0.019) and P-Smad2 (p = 0.006) expression in osteosarcoma. Kaplan-Meier analysis showed that tumour extension (p = 0.0038), TNM stage (p = 0.0096), and p21/WAF1 expression (p = 0.0023) were significantly correlated with overall survival. Cox multivariate analysis showed that tumour extension (p = 0.048) and p21/WAF1 expression (p = 0.022) were independent poor prognostic factors.

CONCLUSIONS

Smad signalling in osteosarcoma is partially operative. The high p21/WAF1 expression in osteosarcoma is significantly correlated with tumour extension. Our results suggest that overexpression of p21/WAF1 in osteosarcoma might be one of the poor prognostic factors.

Advances in pancreatic cancer detection

Pancreatic cancer represents a major challenge for research studies and clinical management. No specific tumor marker for the diagnosis of pancreatic cancer exists. Therefore, extensive genomic, transcriptomic, and proteomic studies are being developed to identify candidate markers for use in high-throughput systems capable of large cohort screening. Understandably, the complex pathophysiology of pancreatic cancer requires sensitive and specific biomarkers that can improve both early diagnosis and therapeutic monitoring. The lack of a single diagnostic marker makes it likely that only a panel of biomarkers is capable of providing the appropriate combination of high sensitivity and specificity. Biomarker discovery using novel technology can improve prognostic upgrading and pinpoint new molecular targets for innovative therapy.

Inhibitory effect of p21WAF1 gene transfection on proliferation of human pancreatic cancer cell line BxPC-3

AIM: To investigate the effect of p21^WAF1 (p21) gene transfection on the proliferation of human pancreatic cancer line BxPC-3.

METHODS: According to the different transfected plasmid and whether the transfection was performed, 3 groups were formed. For p21 transfection group, pCDNA3.1 (+)-p21 was transfected into BxPC-3 cell by the vector of Lipofectamine2000. For empty plasmid transfection group, pCDNA3.1 (+)-neo plasmid was transfected into BxPC-3 cell with the same method as the blank control group. For non-transfection group, the BxPC-3 cell was not transfected as the negative control group. The expression of p21 was evaluated using RT-PCR and Western blot. The proliferation and apoptosis were determined by MTT, flow cytometry and transmission electron microscopy.

RESULTS: After transfection, the expression of p21 mRNA and P21 protein was up regulated, and the cell growth was decreased. High protein expression of P21 BxPC-3 cell cycle was arrested at G₁/S phase, the population of G₁ phase was significantly increased, compared with the empty plasmid transfection group or the non-transfection group (59.887% ± 3.700% vs 47.443% ± 6.354%, 49.223% ± 2.226%, P < 0.05), the S phase population was significantly decreased (21.277% ± 2.080% vs 35.247% ± 3.966%, 36.013% ± 1.540%, P < 0.01), and a Sub-G₁ peak (apoptosis peak) appeared. Cell apoptosis by transmission electron microscopy was observed in the pCDNA3.1 (+)-p21 transfection group BxPC-3 cells.

CONCLUSION: After p21 gene transfection, BxPC-3 cell proliferation is significantly arrested and apoptosis could be induced in vitro.