Identification of DNA methylation of SOX9 in cervical cancer using methylated-CpG island recovery assay

Clinicopathological and prognostic significance of SOX9 expression in gastric cancer patients: A meta-analysis

BACKGROUND

SOX9 is a potential prognostic marker in gastric cancer (GC) patients. This meta-analysis aimed to highlight the clinicopathological and prognostic implications of SOX9 expression in GC patients.

METHODS

A systematic literature search was conducted to identify relevant studies by the electronic literature databases (PubMed, Web of Science, EMBASE and Chinese databases). Review Manager version 5.4 was employed to evaluate the pooled odds ratio (OR) or hazard ratio (HR) with 95% confidence intervals (CIs).

RESULTS

Seventeen studies with a total of 2893 GC patients were enrolled in this meta-analysis. The analysis with ten articles clarified that higher expression of SOX9 was observed in GC cancers than that of normal gastric samples (OR = 16.26; 95% CI: 8.16 to 32.42; P < .00001). Consequently, the results also showed that SOX9 expression was closely associated with age (OR = 1.34; 95% CI: 1.04-1.72; P = .03), tumor size (OR = 0.67; 95% CI: 0.49-0.91; P = .01), histological differentiation (OR = 0.62; 95% CI: 0.36-1.06; P = .002), tumor stage (OR = 0.48; 95% CI: 0.20-1.12; P = .04), lymph node metastasis (OR = 0.36; 95% CI: 0.19-0.67; P = .0010) and advanced TNM stage (OR = 0.46; 95% CI: 0.30-0.70; P = .0003), but not significantly related to gender, distant metastasis and vascular invasion. Furthermore, high SOX9 expression could significantly indicate poorer overall survival (OS) (HR = 1.40; 95% CI: 1.14-1.72; P = .001).

CONCLUSION

SOX9 overexpression might be related to poor prognosis and could serve as a potential predictive marker of poor clinicopathological prognosis factor in GC patients.

Prognostic value of SOX9 in cervical cancer: Bioinformatics and experimental approaches

Among gynecological cancers, cervical cancer is a common malignancy and remains the leading cause of cancer-related death for women. However, the exact molecular pathogenesis of cervical cancer is not known. Hence, understanding the molecular mechanisms underlying cervical cancer pathogenesis will aid in the development of effective treatment modalities. In this research, we attempted to discern candidate biomarkers for cervical cancer by using multiple bioinformatics approaches. First, we performed differential expression analysis based on cervical squamous cell carcinoma and endocervical adenocarcinoma data from The Cancer Genome Atlas database, then used differentially expressed genes for weighted gene co-expression network construction to find the most relevant gene module for cervical cancer. Next, the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed on the module genes, followed by using protein–protein interaction network analysis and Cytoscape to find the key gene. Finally, we validated the key gene by using multiple online sites and experimental methods. Through weighted gene co-expression network analysis, we found the turquoise module was the highest correlated module with cervical cancer diagnosis. The biological process of the module genes focused on cell proliferation, cell adhesion, and protein binding processes, while the Kyoto Encyclopedia of Genes and Genomes pathway of the module significantly enriched pathways related to cancer and cell circle. Among the module genes, SOX9 was identified as the hub gene, and its expression was associated with cervical cancer prognosis. We found the expression of SOX9 correlates with cancer-associated fibroblast immune infiltration in immune cells by Timer2.0. Furthermore, cancer-associated fibroblast infiltration is linked to cervical cancer patients’ prognosis. Compared to those in normal adjacent, immunohistochemical and real-time quantitative polymerase chain reaction (qPCR) showed that the protein and mRNA expression of SOX9 in cervical cancer were higher. Therefore, the SOX9 gene acts as an oncogene in cervical cancer, interactive with immune infiltration of cancer-associated fibroblasts, thereby affecting the prognosis of patients with cervical cancer.

SOX9: Advances in Gynecological Malignancies

Transcription factors of the SOX family were first discovered in mammals in 1990. The sex-determining region Y box 9 belongs to the SOX transcription factor family. It plays an important role in inducing tissue and cell morphogenesis, survival, and many developmental processes. Furthermore, it has been shown to be an oncogene in many tumors. Gynecological malignancies are tumors that occur in the female reproductive system and seriously threaten the lives of patients. Common gynecological malignancies include ovarian cancer, cervical cancer, and endometrial cancer. So far, the molecular mechanisms related to the incidence and development of gynecological malignancies remain unclear. This makes it particularly important to discover their common causative molecule and thus provide an effective therapeutic target. In recent years, studies have found that multiple mechanisms are involved in regulating the expression of the sex-determining region Y box 9, leading to the occurrence and development of gynecological malignancies. In this review, we discuss the prognostic value of SOX9 expression and the potential of targeting SOX9 for gynecological malignancy treatment. We also discuss progress regarding the role of SOX9 in gynecological malignancy pathogenesis through its mediation of important mechanisms, including tumor initiation and proliferation, apoptosis, migration, invasion, chemoresistance, and stem cell maintenance.

Cervical cancer progression is regulated by SOX transcription factors: Revealing signaling networks and therapeutic strategies

Cervical cancer is the fourth common gynecologic cancer and is considered as second leading cause of death among women. Various strategies are applied in treatment of cervical cancer including radiotherapy, chemotherapy and surgery. However, cervical cancer cells demonstrate aggressive behavior in advanced phases, requiring novel strategies in their elimination. On the other hand, SOX proteins are transcription factors capable of regulating different molecular pathways and their expression varies during embryogenesis, disease development and carcinogenesis. In the present review, our aim is to reveal role of SOX transcription factors in cervical cancer. SOX transcription factors play like a double-edged sword in cancer. For instance, SOX9 possesses both tumor-suppressor and tumor-promoting role in cervical cancer. Therefore, exact role of each SOX members in cervical cancer has been discussed to direct further experiments for revealing other functions. SOX proteins can regulate proliferation and metastasis of cervical cancer cells. Furthermore, response of cervical cancer cells to chemotherapy and radiotherapy is tightly regulated by SOX transcription factors. Different downstream targets of SOX proteins such as Wnt signaling, EMT and Hedgehog have been identified. Besides, upstream mediators such as microRNAs, lncRNAs and circRNAs can regulate SOX expression in cervical cancer. In addition to pre-clinical studies, role of SOX transcription factors as prognostic and diagnostic tools in cervical cancer has been shown.

Klotho promoter methylation status and its prognostic value in ovarian cancer

Among all gynecological cancers, ovarian cancer (OC) is one of the deadliest types of cancer worldwide. Epigenetic silencing of some genes has been reported to be associated with OC. In this context, Klotho (KL) gene methylation is a promising biomarker for OC. The present study aimed to investigate the methylation profiles of KL and assess its prognostic value. A total of 63 formalin-fixed paraffin-embedded tissue samples from patients with primary OC were collected and analyzed in the present study. The methylation profiles of KL were assessed by performing DNA bisulfate treatment followed by DNA promoter methylation analysis using the MethyLight assay. The results revealed KL promoter hypermethylation in 62% of the OC cohort. Additionally, significant associations were observed between KL methylation profiles and tumor subtype (P<0.0001) and tumor site (P=0.039). Furthermore, Kaplan-Meier analysis revealed that a worse disease-specific survival was significantly associated with hypermethylated KL (P=0.03, log-rank; hazard ration, 0.58; 95% confidence interval (CI), 0.26-0.90). Cox regression multivariate analysis indicated that KL promoter methylation was an independent OC prognostic indicator (P=0.029). The current study suggested that KL may be a novel biomarker to predict prognosis in patients with OC, since patients with higher KL promoter methylation were more likely to have a poor prognosis and would therefore require frequent follow-up and integrative personalized therapeutic approaches.

Interplay between SOX9 transcription factor and microRNAs in cancer

SOX transcription factors are critical regulators of development, homeostasis and disease progression and their dysregulation is a common finding in various cancers. SOX9 belongs to SOXE family located on chromosome 17. MicroRNAs (miRNAs) possess the capacity of regulating different transcription factors in cancer cells by binding to 3'-UTR. Since miRNAs can affect differentiation, migration, proliferation and other physiological mechanisms, disturbances in their expression have been associated with cancer development. In this review, we evaluate the relationship between miRNAs and SOX9 in different cancers to reveal how this interaction can affect proliferation, metastasis and therapy response of cancer cells. The tumor-suppressor miRNAs can decrease the expression of SOX9 by binding to the 3'-UTR of mRNAs. Furthermore, the expression of downstream targets of SOX9, such as c-Myc, Wnt, PI3K/Akt can be affected by miRNAs. It is noteworthy that other non-coding RNAs including lncRNAs and circRNAs regulate miRNA/SOX9 expression to promote/inhibit cancer progression and malignancy. The pre-clinical findings can be applied as biomarkers for diagnosis and prognosis of cancer patients.

SOX9: An emerging driving factor from cancer progression to drug resistance

Dysregulation of transcription factors is one of the common problems in the pathogenesis of human cancer. Among them, SOX9 is one of the critical transcription factors involved in various diseases, including cancer. The expression of SOX9 is regulated by microRNAs (miRNAs), methylation, phosphorylation, and acetylation. Interestingly, SOX9 acts as a proto-oncogene or tumor suppressor gene, relying upon kinds of cancer. Recent studies have reported the critical role of SOX9 in the regulation of the tumor microenvironment (TME). Additionally, activation of SOX9 signaling or SOX9 regulated signaling pathways play a crucial role in cancer development and progression. Accumulating evidence also suggests that SOX9 acquires stem cell features to induce epithelial-mesenchymal transition (EMT). Moreover, SOX9 has been broadly studied in the field of cancer stem cell (CSC) and EMT in the last decades. However, the link between SOX9 and cancer drug resistance has only recently been discovered. Furthermore, its differential expression could be a potential biomarker for tumor prognosis and progression. This review outlined the various biological implications of SOX9 in cancer progression and cancer drug resistance and elucidated its signaling network, which could be a potential target for designing novel anticancer drugs.

SOX9: The master regulator of cell fate in breast cancer

SRY-related high-mobility group box 9 (SOX9) is an indispensable transcription factor that regulates multiple developmental pathways related to stemness, differentiation, and progenitor development. Previous studies have demonstrated that the SOX9 protein directs pathways involved in tumor initiation, proliferation, migration, chemoresistance, and stem cell maintenance, thereby regulating tumorigenesis as an oncogene. SOX9 overexpression is a frequent event in breast cancer (BC) subtypes. Of note, the molecular mechanisms and functional regulation underlying SOX9 upregulation during BC progression are still being uncovered. The focus of this review is to appraise recent advances regarding the involvement of SOX9 in BC pathogenesis. First, we provide a general overview of SOX9 structure and function, as well as its involvement in various kinds of cancer. Next, we discuss pathways of SOX9 regulation, particularly its miRNA-mediated regulation, in BC. Finally, we describe the involvement of SOX9 in BC pathogenesis via its regulation of pathways involved in regulating cancer hallmarks, as well as its clinical and therapeutic importance. In general, this review article aims to serve as an ample source of knowledge on the involvement of SOX9 in BC progression. Targeting SOX9 activity may improve therapeutic strategies to treat BC, but precisely inhibiting SOX9 using drugs and/or small peptides remains a huge challenge for forthcoming cancer research.

TNFAIP8 promotes cisplatin resistance in cervical carcinoma cells by inhibiting cellular apoptosis

Cervical cancer is the second most prevalent malignant tumor in women worldwide. Failure of successful treatment is most prevalent in patients with the metastatic disease and the chemotherapy refractory disease. Tumor necrosis factor α-induced protein 8 (TNFAIP8) serves as an anti-apoptotic and pro-oncogenic protein, and is associated with cancer progression and poor prognosis in a number of different cancer types. However, the physiological and pathophysiological roles of TNFAIP8 in cervical carcinogenesis and development remain poorly understood. In the present study, it was demonstrated that TNFAIP8 protein expression levels were significantly increased in cervical cancer tissues compared with the non-tumor adjacent tissues using immunohistochemistry. Additionally, it was demonstrated that TNFAIP8 overexpression is associated with cisplatin resistance. Furthermore, depletion of TNFAIP8 impaired HeLa cell proliferation and viability in vitro, improved cisplatin sensitivity, and promoted cisplatin-induced cellular apoptosis and death. Subsequent mechanistic analysis demonstrated that TNFAIP8 silencing promoted caspase-8/-3 activation and p38 phosphorylation in HeLa cells treated with cisplatin, whereas apoptosis regulator B-cell lymphoma-2 expression was inhibited with TNFAIP8-silenced HeLa cells following treatment with cisplatin. These data suggested that TNFAIP8 serves as an anti-apoptotic protein against cisplatin-induced cell death, which eventually leads to chemotherapeutic drug-treatment failure. Therefore, the present data suggested that TNFAIP8 may be a promising therapeutic target for the treatment of cervical cancer.

Recent Advances on the Molecular Mechanism of Cervical Carcinogenesis Based on Systems Biology Technologies

Cervical cancer is one of the common malignancies in women worldwide. Exploration of pathogenesis and molecular mechanism of cervical cancer is pivotal for development of effective treatment for this disease. Recently, systems biology approaches based on high-throughput technologies have been carried out to investigate the expression of some genes and proteins in genomics, transcriptomics, proteomics, and metabonomics of cervical cancer. Compared with traditional methods，systems biology technology has been shown to provide large of information regarding prognostic biomarkers and therapeutic targets for cervical cancer. These molecular signatures from system biology technology could be useful to understand the molecular mechanisms of cervical cancer development and progression, and help physicians to design targeted therapeutic strategies for patients with cervical cancer.

[Effect of down-regulation of sex determining region Y-box 9 on epithelial mesenchymal transition and cloning of oral squamous carcinoma cells]

OBJECTIVE

To investigate the effect of sex determining region Y-box 9 (SOX9) on epithelial mesenchymal transition (EMT) and cloning of oral squamous cell carcinoma (OSCC).

METHODS

siRNA control, SOX9 siRNA were transfected into BcaCD885 cells in OSCC. Simultaneously, cells that did not undergo transfection were used as the control. Quantitative real time polymerase chain reaction (qRT-PCR) and Western blot were used to select SOX9 siRNA1 with enhanced interference effect. A cell cloning assay was used to determine the cell's clone formation ability. E-cadherin and Vimentin expressions were detected by immunofluorescence. The expressions of E-cadherin, matrix metalloprotease 2 (MMP-2), Vimentin and matrix metalloprotease 9 (MMP-9) were detected by Western blot. Cell invasion and migration were detected in the Transwell compartment.

RESULTS

The levels of SOX9 mRNA and protein in SOX9 siRNA cells were significantly lower than those of the control (P<0.05). An increase in the number of SOX9 siRNA1 cell clonesled to the considerable decrease of the number of cell invasion and migration. In addition, levels of MMP-2 and MMP-9 proteins in cells decreased significantly compared with the control (P<0.05). The level of Vimentin expression in SOX9 siRNA1 cells decreased, and expression level of E-cadherin was elevated. Cell EMT was inhibited compared with the control, and the difference was statistically significant (P<0.05).

CONCLUSIONS

Down-regulation of SOX9 inhibited EMT, clonogenic formation, cell invasion and OSCC migration.

SOX9, a potential tumor suppressor in cervical cancer, transactivates p21WAF1/CIP1 and suppresses cervical tumor growth

Sex-determining region Y-box 9 protein (SOX9) is a transcription factor that may act as both oncogene and tumor suppressor depending on tumor origin. Here we found that SOX9 expression was progressively decreased in cervical carcinoma in situ and especially in invasive cervical carcinoma, compared with normal cervix tissue. The effects of SOX9 on the proliferation, viability, and tumor formation of cervical carcinoma cells were assessed through the silencing and overexpression of SOX9. Overexpression of SOX9 in cervical carcinoma cells (SiHa and C33A) inhibited cell growth in vitro and tumor formation in vivo. In agreement, the silencing of SOX9 in HeLa cells promoted cell growth in culture and tumor formation in mice. Overexpression of SOX9 transactivated p21^WAF1/CIP1 via a specific promoter region, thus blocking G1/S transition. The quantitative chromatin immunoprecipitation analysis revealed physical interaction between SOX9 and the specific region of the p21^WAF1/CIP1 promoter. We suggest that SOX9 is a potential therapeutic target in cervical carcinoma, that specifically transactivates p21^WAF1/CIP1.

The Role of Epigenomics in the Study of Cancer Biomarkers and in the Development of Diagnostic Tools

Epigenetics plays a key role in cancer development. Genetics alone cannot explain sporadic cancer and cancer development in individuals with no family history or a weak family history of cancer. Epigenetics provides a mechanism to explain the development of cancer in such situations. Alterations in epigenetic profiling may provide important insights into the etiology and natural history of cancer. Because several epigenetic changes occur before histopathological changes, they can serve as biomarkers for cancer diagnosis and risk assessment. Many cancers may remain asymptomatic until relatively late stages; in managing the disease, efforts should be focused on early detection, accurate prediction of disease progression, and frequent monitoring. This chapter describes epigenetic biomarkers as they are expressed during cancer development and their potential use in cancer diagnosis and prognosis. Based on epigenomic information, biomarkers have been identified that may serve as diagnostic tools; some such biomarkers also may be useful in identifying individuals who will respond to therapy and survive longer. The importance of analytical and clinical validation of biomarkers is discussed, along with challenges and opportunities in this field.

Biological implications and therapeutic significance of DNA methylation regulated genes in cervical cancer

Cervical cancer is the second most common cancer among women worldwide. About 528,000 women are diagnosed with cervical cancer contributing to around 266,000 deaths, across the globe every year. Out of these, the burden of 226,000 (85%) deaths occurs in the developing countries, who are less resource intensive to manage the disease. This is despite the fact that cervical cancer is amenable for early detection due to its long and relatively well-known natural history prior to its culmination as invasive disease. Infection with high risk human papillomavirus (hrHPVs) is essential but not sufficient to cause cervical cancer. Although it was thought that genetic mutations alone was sufficient to cause cervical cancer, the current epidemiological and molecular studies have shown that HPV infection along with genetic and epigenetic changes are frequently associated and essential for initiation, development and progression of the disease. Moreover, aberrant DNA methylation in host and HPV genome can be utilized not only as biomarkers for early detection, disease progression, diagnosis and prognosis of cervical cancer but also to design effective therapeutic strategies. In this review, we focus on recent studies on DNA methylation changes in cervical cancer and their potential role as biomarkers for early diagnosis, prognosis and targeted therapy.

Developmental DNA methyltransferase inhibitors in the treatment of gynecologic cancers

INTRODUCTION

DNA methylation has become an attractive target for the treatment of cancer. DNA methyltransferase inhibitors have proven useful for the treatment of myelodysplastic syndrome and are being evaluated in gynecological neoplasias.

AREAS COVERED

We provide an overview of the current knowledge on DNA methylation and cancer and the role of DNA methylation in cervical, ovarian and endometrial carcinomas. The results of recent clinical trials with demethylating agents for cervical and ovarian cancer treatment are also discussed.

EXPERT OPINION

There are few studies of DNA demethylating agents for cervical and ovarian cancer treatment; nevertheless, the results are promising. To accelerate these advances, there are at least two actions that can be simultaneously pursued. One is to greatly increase the number of small clinical exploratory trials with existing demethylating drugs and using methylome analyses to identify predictive factors for response and/or toxicity. The second is finding out epigenetic 'drivers' unique to gynecological cancers and their subtypes, and then proceed to clinical trials in a highly selected population of patients. It is expected that in the future, DNA demethylation could have a role in the treatment of gynecologic cancers.

Evaluation of ZAR1 and SFRP4 methylation status as potentials biomarkers for diagnosis in cervical cancer: exploratory study phase I

CONTEXT

Aberrant hypermethylation of promoter region of tumor suppressor genes could be used as cancer biomarkers.

OBJECTIVE

To test methylation status of ZAR1 and SFRP4 promoter regions as potentials biomarkers for diagnosis of preneoplastic and neoplastic lesions of cervix.

MATERIALS AND METHODS

Cytobrush samples were evaluated by Methylation specific PCR (MSP) and quantitative MSP (qMSP).

RESULTS

ZAR1 and SFRP4 methylation frequency increased as the grade of lesion increased and the differences between normal and cervical cancer (CC) are statistically significant (p < 0.0001). qMSP showed higher ZAR1 and SFRP4 methylation levels in cancer than normal epithelia (p < 0.001) and preneoplastics lesions (p < 0.01).

DISCUSSION

qMSP quantify methylation levels and have high sensitivity and specificity.

CONCLUSION

ZAR1 and SFRP4 qMSP could be used as potential biomarker for CC diagnosis.

Methylation in the promoters of HS3ST2 and CCNA1 genes is associated with cervical cancer in Uygur women in Xinjiang

We assessed the suitability of HS3ST2 and CCNA1 genes as biomarkers for the early detection of cervical cancer in Uygur women in Xinjiang, China. Methylation-specific PCR (MSP) and HPV (HPV16 and HPV18)-specific PCR were performed on 110 cervical samples: 40 normal cervices, 10 cervical intraepithelial neoplasia 1 (CIN1), 10 CIN2, 10 CIN3 and 40 cervical cancer tissues. The expression of the 2 genes was measured by reverse transcription PCR (RT-PCR) in 10 methylation-positive and 10 methylation-negative cervical tissues. We found that both HS3ST2 and CCNA1 genes were methylated in 38 of the 40 cervical cancer tissues, 9 of the 10 CIN3, and 6 of the 10 CIN2. In contrast, methylation of these 2 genes was found in only 1 of the 40 normal tissues and none of 10 CIN1. Furthermore, hypermethylated HS3ST2 and CCNA1 genes were correlated with infection with HPV16 and HPV18 in high-grade squamous intraepithelial lesions (HSILs) and cervical cancer (both p<0.05). The expression of HS3ST2 and CCNA1 genes was lower in the methylation-positive cervical tissues than in the methylation-negative cervical tissues. Our results indicate that HS3ST2 and CCNA1 genes may play important roles in HPV-induced cervical cancer and that patients with specific hypermethylated genes may have a greater risk of progressing to invasive cervical cancer.

High expression of octamer transcription factor 1 in cervical cancer

Cervical carcinoma is the second most prevalent malignancy in females worldwide. The crucial etiologic factors involved in the development of cervical carcinoma include infection with papillomavirus, and the structural or functional mutation of oncogenes and tumor suppressor genes. The abnormal change of octamer transcription factor 1 (OCT1) is associated with tumor progression and a poor patient survival rate. However, little is known regarding the effect of OCT1 in cervical cancer. In the present study, flow cytometry, western blot analysis and quantitative polymerase chain reaction (qPCR) were peformed to identify differentially expressed OCT1 in cervical cancer tissue and adjacent non-cancerous tissues. The normalized OCT1 gene expression in cervical cancer was 5.98 times higher compared with the adjacent non-cancerous tissues. Western blot analysis and flow cytometry assessed the levels of OCT1 protein. The results of these two differential techniques showed that the protein expression level of OCT1 was greater in cervical cancer tissues, which corresponded with the qPCR results. Finally, as OCT1 is a potential target gene for microRNA (miR)-1467, -1185, -4493 and -3919, their expression levels were analyzed in cervical cancer tissues and adjacent non-cancerous tissues; they were downregulated by ~45% in the cervical cancer samples. The results of the present study showed that OCT1 is highly expressed in cervical cancer tissues and indicated that OCT-1 may be significant in cervical cancer.

CD44 affects the expression level of FOS‑like antigen 1 in cervical cancer tissues

Cervical carcinoma is the second most prevalent type of malignancy in females worldwide. The crucial etiological factors involved in the development of cervical carcinoma include infection with the papillomavirus, and the structural or functional mutation of oncogenes and tumor suppressor genes. CD44 refers to a multifunctional family of type I transmembrane proteins. These proteins have been implicated in numerous biological processes, including cell adhesion, cell migration and metastasis. The present study examined the differences in the expression levels of ATP-binding cassette sub-family G member 2, CD24, CD44, CD133, cytokeratin (CK) 14 and CK19 between cervical cancer tissues and corresponding normal non-tumor tissues by flow cytometry. Then, the CD44+ or CD44‑ cells from cervical cancer tissues were sorted for identification and confirmation of differential expression by flow cytometry. The results demonstrated that the expression level of CD44 in cervical cancer tissues was higher than in the corresponding non-tumor normal tissues (t=3.12; P=0.0102). Compared with the CD44‑ cells, the FOS-like antigen 1 (Fra-1), nestin, nuclear receptor subfamily 4, group A, member 2, OCT4 and p63 genes were highly expressed in CD44+ cells. The fold changes were 3.55, 3.55, 2.46, 2.87 and 2.56, respectively (P<0.05). However, BMI1 polycomb ring finger oncogene, ck5, tumor protein p53 and lactotransferrin genes exhibited low expression levels in CD44+ cells. It was verified by western blot analysis and flow cytometry that Fra-1 was highly expressed in CD44+ cells. Fra-1 was a potential target of miR-19a and miR-19b. The expression of miR-19a and miR-19b was downregulated by ~50% in CD44+ cells compared with CD44‑ cells. These findings suggested that CD44 dysregulated the activation of the Fra‑1 gene. The interaction of Fra-1 and CD44 may therefore be important in cervical carcinoma.

Loss of DOK2 induces carboplatin resistance in ovarian cancer via suppression of apoptosis

OBJECTIVE

Ovarian cancers are highly heterogeneous and while chemotherapy is the preferred treatment many patients are intrinsically resistant or quickly develop resistance. Furthermore, all tumors that recur ultimately become resistant. Recent evidence suggests that epigenetic deregulation may be a key factor in the onset and maintenance of chemoresistance. We set out to identify epigenetically silenced genes that affect chemoresistance.

METHODS

The epigenomes of a total of 45 ovarian samples were analyzed to identify epigenetically altered genes that segregate with platinum response, and further filtered with expression data to identify genes that were suppressed. A tissue culture carboplatin resistance screen was utilized to functionally validate this set of candidate platinum resistance genes.

RESULTS

Our screen correctly identified 19 genes that when suppressed altered the chemoresistance of the cells in culture. Of the genes identified in the screen we further characterized one gene, docking protein 2 (DOK2), an adapter protein downstream of tyrosine kinase, to determine if we could elucidate the mechanism by which it increased resistance. The loss of DOK2 decreased the level of apoptosis in response to carboplatin. Furthermore, in cells with reduced DOK2, the level of anoikis was decreased.

CONCLUSIONS

We have developed a screening methodology that analyzes the epigenome and informatically identifies candidate genes followed by in vitro culture screening of the candidate genes. To validate our screening methodology we further characterized one candidate gene, DOK2, and showed that loss of DOK2 induces chemotherapy resistance by decreasing the level of apoptosis in response to treatment.