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S1. Apoptosis detected by TUNEL in MDA-MB-231 cells expressing shSEMA4C or EV. S2. Sema4C cDNA re-expressed in these MDA-MB-231 siSEMA4C cells could recover cell growth and ANG and CSF secretion. S3. Expression of senescence-associated pathway proteins in MDA-MB-231 cells were examined using western blot post-transfection at the indicated time. S4. SEMA4C regulates angiogenesis. S5. The vascular integrity was detected in EV tumours and shSEMA4C tumours. S6. Sections from tumors were immunostained with anti-cd45 (white arrowhead) or F4/80(black arrow) antibody. S7. SEMA4C regulates macrophage recruitment. S8. The vascular density and macrophage area were detected in EV tumours and shSEMA4C tumours at the same weight. S9. Recombinant soluble Sema4C did not affect MDA-MB-231 proliferation and endothelial cells tube formation despite could increase macrophages migration. S10. mRNA levels of ANG and CSF were analyzed in presence of siSEMA4C RNA or sema4C cDNA in MDA-MB-231cells. S11. Expression of mRNA(A) and secreted protein(B) level of ANG and CSF-1 were detected in the MCF-7 cells overexpressing SEMA4C. S12. The growth curve and cell cycle were detected in presence of siANG in MDA-MB-231 cells.

Supplementary Figure 5 from Identification of LIV1, a Putative Zinc Transporter Gene Responsible for HDACi-Induced Apoptosis, Using a Functional Gene Screen Approach

Supplementary Figure 3 from Identification of LIV1, a Putative Zinc Transporter Gene Responsible for HDACi-Induced Apoptosis, Using a Functional Gene Screen Approach

Supplementary Figure 1 from Identification of LIV1, a Putative Zinc Transporter Gene Responsible for HDACi-Induced Apoptosis, Using a Functional Gene Screen Approach

Histone deacetylase inhibitors (HDACi) show promise as a novel class of antitumoral agents and have shown the ability to induce apoptosis of tumor cells. To gain a better understanding of the action of HDACi, we conducted a functional gene screen approach named suppression of mortality by antisense rescue technique to identify the key genes responsible for the tumor-selective killing trichostatin A. Over 20 genes associated with HDACi-induced mortality were identified. One of the confirmed positive hits is LIV1, a putative zinc transporter. LIV1 is significantly induced by treatment with HDACi in a number of tumor cells, but not in normal cells. Knockdown of LIV1 suppressed apoptosis induced by HDACi in tumor cells. Although HDACi induced a slight increase in the free intracellular zinc concentration, knockdown of LIV1 significantly enhanced the intracellular zinc level, which was associated with resistance to apoptosis. On the other hand, pretreatment of the cells with a specific zinc chelator TPEN reversed the apoptosis resistance conferred by knockdown of LIV1. However, the biological effects of TPEN were abolished by addition of physiologic concentrations of zinc. Taken together, the present study identifies LIV1 as a critical mediator responsible for HDACi-induced apoptosis. The effect of LIV1 is, at least in part, mediated by affecting intracellular zinc homeostasis, which may be related to alteration of the catalytic activity of the Caspase 3 and expression of some BCL-2 family genes. As such, these findings highlight a novel mechanism underlying the action of HDACi that could be potentially useful in the clinical setting. [Mol Cancer Ther 2009;8(11):3108–16]

Supplementary Figure 2 from Identification of LIV1, a Putative Zinc Transporter Gene Responsible for HDACi-Induced Apoptosis, Using a Functional Gene Screen Approach

Supplementary Figure 4 from Identification of LIV1, a Putative Zinc Transporter Gene Responsible for HDACi-Induced Apoptosis, Using a Functional Gene Screen Approach

Objective: The objective of this study was to evaluate the application of DNA ploidy analysis in large-scale population screening for cervical cancer. Methods: From March 2016 to March 2019, eligible subjects were enrolled and recommended to undergo DNA ploidy analysis, the ThinPrep cytology test (TCT), and high-risk human papillomavirus (hrHPV) detection concurrently. Patients with positive results were recommended for colposcopy, and biopsy diagnosis was regarded as the “gold standard.” We compared the test efficiencies of the 3 methods and compared the efficiency and accuracy of the TCT in our hospital and the “2-cancer screening” project in Hubei Province during the same period. Results: Among 20,574 women, the positive rates of DNA ploidy analysis, cytology, and hrHPV testing were 4.01%, 4.71%, and 16.28%, respectively. The sensitivities of these methods for screening for grade 2+ cervical intraepithelial neoplasia were 0.70, 0.68, and 0.96, and their specificities were 0.79, 0.82, and 0.45, respectively. On comparing DNA ploidy analysis with the TCT, there was no significant difference in the sensitivity, specificity, positive predictive value, negative predictive value, and missed diagnosis rate. In opportunistic screening and the 2-cancer screening project, the positive rates of cytology were 4.71% and 2.87%, respectively. And the efficiency and accuracy of the TCT in opportunistic screening were higher than in the 2-cancer screening project. Conclusion: Therefore, DNA ploidy analysis, which is of low-cost and does not depend on cytopathologists, can replace cytology and be applied in large-scale population screening for cervical cancer.

BackgroundEmerging evidence indicates that the tumor microenvironment influences tumor progression and patient prognosis through various inflammatory cells. Polymorphonuclear neutrophils (PMNs) and their functional structures termed neutrophil extracellular traps (NETs) are prominent constituents of several malignant tumors and affect the tumor microenvironment and cancer evolution. Here, we investigate the prognostic value of PMNs and NETs for recurrence in patients with cervical cancer.MethodsThe study comprised 126 cervical cancer patients who were retrospectively enrolled. CD66b+ neutrophils and myeloperoxidase/citrullinated histone H3 (MPO/H3Cit)-labeled NETs were assessed by immunofluorescence, and the relationships with clinical and histopathologic features and patient outcome were evaluated.ResultsThe highest density of CD66b+ neutrophils were observed in the stromal compartment (median 55 cells/mm2). Above median densities of stromal CD66b+ neutrophils and NETs were significantly associated with short recurrence-free survival (RFS) (P = 0.041 and P = 0.006, respectively). Multivariate analysis identified high clinical stage (hazard ratio [HR] 6.40; 95% confidence interval [CI] 3.51-11.64; P < 0.001), lymph node metastases (HR 4.69; 95% CI 3.09-9.66; P = 0.006) and high density of NETs (HR 2.66; 95% CI 1.21-5.82; P = 0.015) as independent prognostic factors for short RFS, whereas a high density of CD66b+ neutrophils was not significant. Patients with a high NET density showed worse recurrence status in every stage, but the difference was only significant for stage I (P = 0.042), not stages II, III, or IV (all P > 0.05). Combining stromal NET density and the tumor, nodes, metastasis (TNM) staging system had better prognostic accuracy for cervical cancer than the TNM staging system alone at five and six years respectively (P = 0.010 and P = 0.023).ConclusionStromal NET density is an independent prognostic factor for RFS in cervical cancer. Combining NETs with the TNM staging system may further improve prognostic stratification.

Objective To investigate the safety and efficacy of mixed methylene blue (MB) compound injection for treatment of vulvar non-neoplastic epithelial disorders (NNEDs). Methods A prospective observational study among 118 women with vulvar NNEDs treated with intradermal injection of mixed MB compound at a hospital in Wuhan, China, between 2013 and 2016. Itching score, skin hypopigmentation area percentage (SHAP), and recurrence were assessed by interview and physical examination before and after treatment. Adverse effects were recorded. Results Before treatment, mean ± SD itching score was 7.78 ± 1.59. It decreased rapidly immediately after treatment and remained low thereafter (1.82 ± 2.31, 1.69 ± 2.39, 1.97 ± 2.73, 2.05 ± 2.72, and 2.19 ± 2.86 at 1, 3, 6, 12, and 24 months, respectively). Before treatment, mean ± SD SHAP was 28.01% ± 18.28%. SHAP decreased gradually and remained stably low 6 months later (26.28% ± 17.95%, 21.19% ± 18.42%, 19.19% ± 18.67%, 18.68% ± 18.91%, and 18.65% ± 19.20% at 1, 3, 6, 12, and 24 months, respectively). The recurrence rate in 2 years was 21.2% (25/118) with no major complications. Conclusions Intradermal injection of mixed MB compound was found to be an effective and safe treatment for vulvar NNEDs. ClinicalTrials.gov: NCT03200808.

High-risk human papillomavirus (hrHPV) infection plays an important role in the development of cervical intraepithelial neoplasia and cervical cancer. A total of 11 549 women were enrolled from the Maternal and Child Health Hospital of Hubei Province. Each participant accepted hrHPV testing and completed a self-administered questionnaire about basic information and potential risk factors. The univariable and multivariable logistic regression model was used to explore the associations between variants and hrHPV infection. Our results showed that hrHPV prevalence was 16.09% in Hubei Province, among which, hrHPV was more likely to be positive in women aged 51 years or above (OR=1.65, 95% CI: 1.28-2.14), and in women who had symptoms of bleeding after intercourse (OR=1.32, 95% CI:1.17-1.50), had first sexual intercourse at the age of 18 years or below (OR=1.33, 95% CI:1.07-1.64), had at least three male sexual partners (OR=2.50, 95% CI:2.07-3.03), and who had been diagnosed with sexually transmitted infections (OR=1.50, 95% CI:1.12-2.03). Married women (OR=0.66, 95% CI: 0.55-0.78) and women who frequently used condoms (OR=0.75, 95% CI:0.67-0.84) had a relatively lower hrHPV prevalence. This study confirms that hrHPV infection was associated with age, marital status, symptoms of intercourse bleeding, history of sexually transmitted infections, and sex-related behaviors. Above all, this study provides a baseline database prior to obtaining vaccinations for dynamic tracking of the changes in hrHPV prevalence.

The current outbreak of coronavirus disease 2019 (COVID-19) has been defined as a pandemic by the World Health Organization. We aimed to evaluate the clinical features and virological course of non-severe COVID-19 patients with or without symptoms who were admitted to a Chinese cabin hospital. In this retrospective single center study, we reviewed 252 laboratory-confirmed COVID-19 patients treated at one temporary cabin hospital in Wuhan, China. Demographic, clinical, serial chest computed tomography (CT), and serial viral test data were compared between asymptomatic and symptomatic patients. The association between clinical features and symptomatic status or patient referral status was analyzed. Among all 252 patients, 74 (29.4%) were asymptomatic and 138 (54.76%) had more than two family members who developed COVID-19. The probability for family clustering was similar between asymptomatic and symptomatic patients (59.70 vs. 61.64%, P = 0.79). Asymptomatic patients and symptomatic patients were equally likely to reach a virus-free state during their stay at the cabin hospital (93.15 vs. 86.44%, P = 0.13). The initial chest CT screening showed that 81 (32.1%) patients had no visible pneumonia, 52 (20.6%) had unilateral pneumonia, and 119 (47.2%) had bilateral pneumonia. Symptomatic patients had a higher chance to have bilateral pneumonia (P < 0.0001) and were less likely to show improvement on the follow-up CT scan (P = 0.0002). In total, 69 (27.4%) patients were referred to the designated hospital and only 23 (9.1%) patients were referred due to the progression of pneumonia. Non-severe COVID-19 patients can transmit the disease regardless of their symptomatic status. It is highly recommended that asymptomatic patients be identified and quarantined to eliminate the transmission of COVID-19.

Background: 2019 novel coronavirus disease (COVID-19) has been characterized as a pandemic by WHO Clinical and virological course of patients with severe disea

// Ye Li 1, 2 , Lu Jin 2 , Fei Ye 3 , Quanfu Ma 1 , Zongyuan Yang 1 , Dan Liu 1 , Jie Yang 1 , Ding Ma 1 and Qinglei Gao 1 1 Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China 2 Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington DC, USA 3 Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China Correspondence to: Qinglei Gao, email: qlgao@tjh.tjmu.edu.cn Keywords: EphA10s, EphA10, E-Cadherin complex, breast cancer, lymph node metastasis Received: April 10, 2016 Accepted: February 07, 2017 Published: March 06, 2017 ABSTRACT Overexpression of EPHA10 protein was reported in concomitance with clinical severity of breast cancer. In this study, we annotate overexpression of EPHA10 protein with changes of isoform expression as EphA10s (EPHA10 isoform 2) and EphA10 (EPHA10 isoform 3). In the process of malignant transformation, secretory protein EphA10s is in low expression, and pseudo-kinase EphA10 is overexpressed and cytoplasmically enriched. Down-regulated EphA10s blunts stabilization of membrane-associate β-catenin via the interaction with ephrin A5. Cytoplasmic EphA10 maintains phosphorylation of E-cadherin. Restoring isoform expression pattern by up-regulated EphA10s and down-regulated cytoplasmic EphA10 inhibits cell invasion and lymph node metastasis by strengthening the stability of the complex of E-cadherin and β-catenin in membrane. Taken together, we defined the novel interaction via expression patterns of EphA10s and EphA10 that promote malignant transformation of breast cancer, and demonstrated the potential benefit in clinical usage.

Purpose: Lymphatic vessels are mainly regarded as passive conduits for the dissemination of cancer cells. In this study, we investigate whether and how the tumor-associated lymphatic vessels may play an active role in tumor metastasis. Experimental Design: In situ laser capture microdissection of lymphatic vessels followed by cDNA microarray analysis was used to determine the expression profiling of lymphatic endothelial cells (LEC). Gene expression levels and activity of signaling pathways were measured by real-time RT-PCR, ELISA, or immunoblotting. Lymphangiogenesis was assessed by IHC. Lymph node metastasis was measured using fluorescence imaging. The effects of SEMA4C on lymphangiogenesis in vitro were evaluated using migration assay and tube-formation assay of LECs. Results: Tumor-associated LECs are molecularly and functionally different from their normal counterparts. In addition to expressing high levels of membrane-bound SEMA4C, tumor-associated LECs also produced soluble SEMA4C (sSEMA4C). Increased serum sSEMA4C was detected in patients with breast cancer and cervical cancer. Patients with metastasis had much higher levels of serum sSEMA4C. sSEMA4C promoted lymphangiogenesis by activating PlexinB2-ERBB2 signaling in LECs, and promoted the proliferation and migration of tumor cells by activating PlexinB2-MET signaling, thus promoting lymphatic metastasis. Although the SEMA4C signaling pathways differ between LECs and tumor cells, RHOA activation was necessary for the effects of SEMA4C in both types of cells. Conclusions: Tumor-associated LECs produce sSEMA4C to promote lymphatic metastasis of tumors. Our results suggest that SEMA4C and RHOA might be potential therapeutic targets, and that higher serum sSEMA4C could be a marker for breast cancer and cervical cancer. Clin Cancer Res; 23(1); 214–24. ©2016 AACR.

Semaphorins are a large family of evolutionarily conserved morphogenetic molecules that are associated with repelling axonal guidance. Intriguingly, recent researches indicate that semaphorins are involved in cancer progression. Semaphorin 4C (SEMA4C) has long been considered a neuronal migration gene, but we detected that it is also highly expressed in many malignant human cancers. During an investigation of subcutaneous tumor models, we found that SEMA4C expression promoted tumor growth and progression. We discovered that SEMA4C was involved in maintaining tumor cell self-renewal, likely by regulating the p53 pathway. Inhibiting the expression of endogenous SEMA4C in tumor cells impaired growth and induced senescence and cell-cycle arrest in the G2-phase. In addition, we found that SEMA4C induced the production of angiogenin and colony-stimulating factor-1 (CSF-1) in tumor cells by activating the NF-κB pathway in a plexinB2-dependent manner. In conclusion, SEMA4C expression in breast cancer cells promotes cancer cell proliferation, macrophage recruitment, and angiogenesis. Thus, inhibition of SEMA4C activity may be a novel therapeutic strategy for human breast cancer. Implications: In breast cancer, therapeutic targeting of the SEMA4C pathway may prevent tumor growth, angiogenesis, metastasis, and progression.

Histone deacetylase inhibitors (HDACi) show promise as a novel class of antitumoral agents and have shown the ability to induce apoptosis of tumor cells. To gain a better understanding of the action of HDACi, we conducted a functional gene screen approach named suppression of mortality by antisense rescue technique to identify the key genes responsible for the tumor-selective killing trichostatin A. Over 20 genes associated with HDACi-induced mortality were identified. One of the confirmed positive hits is LIV1, a putative zinc transporter. LIV1 is significantly induced by treatment with HDACi in a number of tumor cells, but not in normal cells. Knockdown of LIV1 suppressed apoptosis induced by HDACi in tumor cells. Although HDACi induced a slight increase in the free intracellular zinc concentration, knockdown of LIV1 significantly enhanced the intracellular zinc level, which was associated with resistance to apoptosis. On the other hand, pretreatment of the cells with a specific zinc chelator TPEN reversed the apoptosis resistance conferred by knockdown of LIV1. However, the biological effects of TPEN were abolished by addition of physiologic concentrations of zinc. Taken together, the present study identifies LIV1 as a critical mediator responsible for HDACi-induced apoptosis. The effect of LIV1 is, at least in part, mediated by affecting intracellular zinc homeostasis, which may be related to alteration of the catalytic activity of the Caspase 3 and expression of some BCL-2 family genes. As such, these findings highlight a novel mechanism underlying the action of HDACi that could be potentially useful in the clinical setting. [Mol Cancer Ther 2009;8(11):3108–16]

Tumor cells acquire the ability to proliferate uncontrollably, resist apoptosis, sustain angiogenesis and evade immune surveillance. Signal transducer and activator of transcription (STAT) 3 regulates all of these processes in a surprisingly large number of human cancers. Consequently, the STAT3 protein is emerging as an ideal target for cancer therapy. This paper reports the generation of an oncolytic adenovirus (M4), which selectively blocks STAT3 signaling in tumor cells as a novel therapeutic strategy. M4 selectively replicated in tumor cells and expressed high levels of antisense STAT3 complementary DNA during the late phase of the viral infection in a replication-dependent manner. The viral progeny yield of M4 in tumor cells was much higher than that of the parent adenoviral mutants, Ad5/dE1A. M4 effectively silenced STAT3 and its target genes in tumor cells while sparing normal cells and exhibited potent antitumoral efficacy in vitro and in vivo. Systemic administration of M4 significantly inhibited tumor growth in an orthotopic gastric carcinoma mouse model, eliminated abdominal cavity metastases and prolonged survival time. In summary, M4 has low toxicity and great potential as a therapeutic agent for different types of cancers.

Total energy and electronic structure calculations for γ′-Fe4N and CoFe3N in the anti-perovskite crystal structure have been performed to understand the structural stability and magnetism using plane-wave pseudopotential method. The virtual crystal approximation (VCA) was used to study order/disorder to examine the effect of the substitution of Co for Fe on the structural stability in CoFe3N alloy. The results show that CoFe3N energetically prefers ordered configuration for Co atoms occupying the corner position. Moreover, the substitution of Co for Fe at corner sites does slightly change the lattice constant, whereas it increases bulk modulus and could hardly changes the ductility. To reveal the role of nitrogen in γ′-Fe4N and CoFe3N, the Mulliken charge and bond population are used as a measure of charge transfers and an analysis of the covalency of these systems, respectively. It turns out that the further distant atoms from the N atom have the larger magnetic moment for γ′-Fe4N and CoFe3N, due to the spin-down electrons transfer from the corner atoms to the face-centered atoms.

A large number of patients with advanced lymphoma become refractory or relapse after initial treatment due to the persistence of minimal residual disease. Ideal immunotherapy strategy for eradicating the minimal residual disease of lymphoma and preventing the tendency to relapse need to be developed. Here, we use a mice model mimicked the disease entities of aggressive B-cell lymphoma dynamically to analyze the host anti-lymphoma immunity during the progression of lymphoma. We have shown that STAT3 activity was gradually enhanced in host immune effector cells with the progression of lymphoma. Inhibition of the STAT3 activity with a small molecule inhibitor was able to effectively enhance the function of both host innate and adaptive immunity, and thereby delayed the progression of lymphoma. Despite the therapeutic benefits were achieved by using of the STAT3 inhibitor, disrupting of STAT3 pathway did not prevent the eventual development of lymphoma due to the presence of point mutation of β2M, which controls immune recognition by T cells. Our findings highlight the complexity of the mechanism of immune evasion; therefore a detailed analysis of genes involved in the immune recognition process should be essential before an elegant immunotherapy strategy could be conducted.

The aim of this study was to evaluate the safety and efficiency of a novel, oncolytic adenovirus mutant M1 administered in conjunction with immunosuppressive agents. Animal models were established by administering purified M1 either intravenously or retroperitoneally. At different time points, blood samples were taken from the mice for testing of liver and renal function. Microscopic examination of the liver was performed to observe pathological changes. Immunohistochemical analyses were used to evaluate the expression of the adenovirus in the liver. Lymphocyte recruitment to the liver and the activation of adenovirus specific T cells were also analyzed. No signs of general toxicity were observed, but transient increases in ALT and Scr were observed following the administration of M1. Microscopic examination revealed a mild inflammatory response in the liver. Compared to intravenous injection, higher expression levels of adenoviral proteins were observed after retroperitoneal injection. Combined treatment with cyclosporine A resolved the liver and kidney dysfunction and increased the concentration of the adenovirus in the liver. The use of the novel oncolytic adenovirus mutant M1 in vivo is safe, and the combined administration of M1 with immunosuppressive agents was able to enhance the effectiveness and safety profile of M1.

Background Mesenchymal stem cells (MSCs) have been considered to be the attractive vehicles for delivering therapeutic agents toward various tumor diseases. This study was to explore the distribution pattern, kinetic delivery of adenovirus, and therapeutic efficacy of the MSC loading of E1A mutant conditionally replicative adenovirus Adv-Stat3(-) which selectively replicated and expressed high levels of anti-sense Stat3 complementary DNA in breast cancer and melanoma cells. Methods We assessed the release ability of conditionally replicative adenovirus (CRAd) from MSC using crystal violet staining, TCID50 assay, and quantitative PCR. In vitro killing competence of MSCs carrying Adv-Stat3(-) toward breast cancer and melanoma was performed using co-culture system of transwell plates. We examined tumor tropism of MSC by Prussian blue staining and immunofluorescence. In vivo killing competence of MSCs carrying Adv-Stat3(-) toward breast tumor was analyzed by comparison of tumor volumes and survival periods. Results Adv-Stat3(-) amplified in MSCs and were released 4 days after infection. MSCs carrying Adv-Stat3(-) caused viral amplification, depletion of Stat3 and its downstream proteins, and led to significant apoptosis in breast cancer and melanoma cell lines. In vivo experiments confirmed the preferential localization of MSCs in the tumor periphery 24 hours after tail vein injection, and this localization was mainly detected in the tumor parenchyma after 72 hours. Intravenous injection of MSCs carrying Adv-Stat3(-) suppressed the Stat3 pathway, down-regulated Ki67 expression, and recruited CD11b-positive cells in the local tumor, inhibiting tumor growth and increasing the survival of tumor-bearing mice. Conclusions These results indicate that MSCs migrate to the tumor site in a time-dependent manner and could be an effective platform for the targeted delivery of CRAd and the amplification of tumor killing effects.

Histone deacetylase inhibitors and proteasome inhibitor are all emerging as new classes of anticancer agents. We chose TSA and PS-341 to identify whether they have a synergistic efficacy on human ovarian cancer cells. After incubated with 500 nM TSA or/and 40 nM PS-341, we found that combined groups resulted in a striking increase of apoptosis and G2/M blocking rates, no matter in A2780, cisplatin-sensitive ovarian cancer cell line OV2008 or its resistant variant C13*. This demonstrated that TSA interacted synergistically with PS-341, which raised the possibility that combined the two drugs may represent a novel strategy in ovarian cancer.

Patients with irreversible hypothyroidism require lifelong levo-thyroxin ( L-T4) replacement therapy, which makes them feel discomfortable. With the development of the thyroid tissues autotransplantation and embryonic stem cell (ESC), this would be a more physiological approach to the treatment of irreversible hypothyroidism. The animal experiments and human clinical trials on thyroid tissues autotransplantation have shown that the autograft can survive and function. The advanced researches have demonstrated that ESC can differentiate into thyroid follicular cells.

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.