STING inhibitors sensitize platinum chemotherapy in ovarian cancer by inhibiting the CGAS-STING pathway in cancer-associated fibroblasts (CAFs).

Chemotherapy resistance in ovarian cancer hampers cure rates, with cancer-associated fibroblasts (CAFs) playing a pivotal role. Despite their known impact on cancer progression and chemotherapy resistance, the specific mechanism by which CAFs regulate the tumor inflammatory environment remains unclear. This study reveals that cisplatin facilitates DNA transfer from ovarian cancer cells to CAFs, activating the CGAS-STING-IFNB1 pathway in CAFs and promoting IFNB1 release. Consequently, this reinforces cancer cell resistance to platinum drugs. High STING expression in the tumor stroma was associated with a poor prognosis, while inhibiting STING expression enhanced ovarian cancer sensitivity. Understanding the relevance of the CGAS-STING pathway in CAFs for platinum resistance suggests targeting STING as a promising combination therapy for ovarian cancer, providing potential avenues for improved treatment outcomes.

Efficacy of poly (ADP-ribose) polymerase inhibitors monotherapy and the impact to subsequent platinum-based chemotherapy in breast cancer susceptibility genes1/2-mutated ovarian cancer patients with secondary platinum-sensitive relapse.

BACKGROUND: The therapeutic effect of poly (ADP-ribose) polymerase inhibitors (PARPi) monotherapy compared with platinum-based chemotherapy, and the impact to subsequent platinum-based chemotherapy after PARPi resistance were inconclusive in breast cancer susceptibility genes (BRCA)1/2-mutated ovarian cancer patients with secondary platinum-sensitive relapse. METHODS: BRCA1/2-mutated patients with secondary platinum-sensitive relapse included in this study did not receive any maintenance regimen after first- and second-line platinum-based chemotherapy, and the secondary platinum-free interval (PFI) was more than 6 months. Patients in study group were treated with PARPi monotherapy until disease progression, and patients in control group were treated with platinum-based chemotherapy without restriction. Progression-free survival (PFS) was defined as the time from third-line therapy to disease progression or death, PFS2 was defined as the time from platinum-based chemotherapy after PARPi resistance to next subsequent therapy or death. Post-recurrence survival (PRS) refers to the survival time after secondary platinum-sensitive relapse. RESULTS: A total of 119 patients were retrospectively analyzed, including 71 (59.7%) in study group and 48 (40.3%) in control group. The objective response rate (ORR: 77.5% vs. 80.0%, p=0.766) and PFS (median: 11.2 vs. 11.0 months, p=0.962) were comparable. The benefit of subsequent platinum-based chemotherapy after PARPi resistance was more pronounced in patients with PARPi treatment for more than 12 months (median PFS2: 8.6 vs. 4.3 months, p=0.040). PARPi monotherapy had no adverse effect on PRS compared with platinum-based chemotherapy (median PRS:41.2 vs. 42.8 months, p=0.323). Compared to patients in control group who had never received PARPi, PARPi monotherapy (median PRS: 41.2 vs. 33.7 months, p=0.019) and post-line treatment with PARPi in the control group (median PRS: 48.1 vs. 33.7 months, p=0.002) could prolong PRS for patients with secondary platinum-sensitive relapse. CONCLUSIONS: PARPi monotherapy was similar to platinum-based chemotherapy for BRCA1/2-mutated ovarian cancer patients with secondary platinum-sensitive recurrence, and could improve prognosis.

Granulocyte-macrophage colony-stimulating factor promotes endometrial repair after injury by regulating macrophages in mice.

Intrauterine adhesion (IUA) caused by endometrial injury is a common cause of female infertility and is challenging to treat. Macrophages play a critical role in tissue repair and cyclical endometrial regeneration. Granulocyte-macrophage colony-stimulating factor (GM-CSF) has significant reparative and anti-fibrotic effects in various tissues. However, there is limited research on the role of GM-CSF in the repair of endometrial injury and the involvement of macrophages in GM-CSF-mediated endometrial repair. In this study, using a mouse model of endometrial scratching injury, we found that GM-CSF treatment accelerated the repair of endometrial injury and improved fertility. At the molecular level, we observed that GM-CSF can downregulate the transcript levels of tumor necrosis factor (TNF) in mouse bone marrow-derived macrophages (BMDMs) stimulated by lipopolysaccharide (LPS) and upregulate the expression of Arginase-1 (Arg-1) and mannose receptor C-type 1 (MRC1). Importantly, during the early and middle stages of injury, GM-CSF increased the proportion of M1-like, M2-like, and M1/M2 mixed macrophages, while in the late stage of injury, GM-CSF facilitated a decline in the number of M2-like macrophages. These findings suggest that GM-CSF may promote endometrial repair by recruiting macrophages and modulating the LPS-induced M1-like macrophages into a less inflammatory phenotype. These insights have the potential to contribute to the development of novel therapeutic approaches for the treatment of intrauterine adhesion and related infertility.

MicroRNA-122-5p alleviates endometrial fibrosis via inhibiting the TGF-ß/SMAD pathway in Asherman's syndrome.

RESEARCH QUESTION: What is the effect of miR-122 on the progression and recovery of fibrosis in Asherman's syndrome? DESIGN: Endometrial tissue was collected from 21 patients, 11 with intrauterine adhesion (IUA) and 10 without IUA. Quantitative real-time polymerase chain reaction, immunofluorescence and Western blot were applied to observe the expression of mRNAs/miRNAs and protein, respectively. The endometrial physical injury was carried out in C57BL/6 mice to create an endometrial fibrosis model, with intrauterine injection of adenovirus to compare the antifibrosis and repair function of miR-122 on endometrium. The morphology of the uterus was observed using haematoxylin and eosin staining, and fibrosis markers were detected by immunohistochemistry. RESULTS: miR-122 expression was reduced in patients with IUAs, accompanied by fibrosis. MiR-122 overexpression reduced the degree of fibrosis in endometrial stromal cells. Further molecular analyses demonstrated that miR-122 inhibited fibrosis through the TGF-ß/SMAD pathway by directly targeting the 3' untranslated region of SMAD family member 3, suppressing its expression. Notably, miR-122 promoted endometrial regeneration and recovery of pregnancy capacity in a mouse endometrial injury model. CONCLUSIONS: miR-122 is a critical regulator for repair of endometrial fibrosis and provided new insight for the clinical treatment of intrauterine adhesions.

Reactive oxygen species-responsive nanocarrier ameliorates murine colitis by intervening colonic innate and adaptive immune responses.

Ulcerative colitis (UC) is a chronic or relapsing inflammatory disease with limited therapeutic outcomes. Pterostilbene (PSB) is a polyphenol-based anti-oxidant that has received extensive interest for its intrinsic anti-inflammatory and anti-oxidative activities. This work aims to develop a reactive oxygen species (ROS)-responsive, folic acid (FA)-functionalized nanoparticle (NP) for efficient PSB delivery to treat UC. The resulting PSB@NP-FA had a nano-scaled diameter of 231 nm and a spherical shape. With ROS-responsive release and ROS-scavenging properties, PSB@NP could effectively scavenge H2O2, thereby protecting cells from H2O2-induced oxidative damage. After FA modification, the resulting PSB@NP-FA could be internalized by RAW 264.7 and Colon-26 cells efficiently and preferentially localized to the inflamed colon. In dextran sulfate sodium (DSS)-induced colitis models, PSB@NP-FA showed a prominent ROS-scavenging capacity and anti-inflammatory activity, therefore relieving murine colitis effectively. Mechanism results suggested that PSB@NP-FA ameliorated colitis by regulating dendritic cells (DCs), promoting macrophage polarization, and regulating T cell infiltration. Both innate and adaptive immunity were involved. More importantly, the combination of the PSB and dexamethasone (DEX) enhanced the therapeutic efficacy of colitis. This ROS-responsive and ROS-scavenging nanocarrier represents an alternative therapeutic approach to UC. It can also be used as an enhancer for classic anti-inflammatory drugs.

Effects of Cystatin C on Cognitive Impairment in Older Chinese Adults.

OBJECTIVE: To find a suitable dividing value to classify cystatin C and evaluate the association between cognition and levels of cystatin C. METHODS: Using data from the China Health and Retirement Longitudinal Study, We conducted a longitudinal analysis of a prospective cohort of 6,869 middle-aged and older Chinese without cognitive impairment at baseline. Levels of cystatin C were categorized into 2 groups by method of decision tree. Logistic regression models evaluated whether cystatin C was related to cognitive impairment. RESULTS: Respondents were categorized as lower levels of cystatin C and higher levels of cystatin C, cut-point was 1.11 mg/L. Higher levels of cystatin C was associated with the odds of cognitive impairment (OR, 1.56; 95% CI, 1.10-2.22) after multivariable adjustment. Respondents with higher levels of cystatin C had worse cognition scores. CONCLUSIONS: We found a suitable dividing value of cystatin C in middle-aged and older Chinese.

Successful pregnancy after complete resection of leiomyomatosis peritonealis disseminate without recurrence:a case report with next-generation sequencing analysis and literature review.

BACKGROUND: Peritoneal leiomyomatosis disseminate (LPD) is a rare disease characterized by widespread dissemination of leiomyomas nodules throughout the peritoneal and omental surfaces. Reports of pregnancy with LPD are even rarer. Therefore, there is no clear consensus on the treatment of LPD on pregnancy, and the pathogenesis is still unclear. CASE PRESENTATION: We reported a case of LPD patient who developed during pregnancy. The patient underwent a cesarean section at 32 weeks of gestation while removing all visible tumors, and no LPD lesions were seen in the subsequent cesarean section at full term. NGS of LPD lesions detected 4 mutations with focal high-level amplifications of CDK4 (cyclin-dependent kinases 4), NBN (Nibrin), DAXX (death domain associated protein), and MYC (myelocytomatosis oncogene). Immunohistochemistry staining analysis among benign leiomyoma, LPD, and leiomyosarcoma verified that LPD was an unusual intermediate between benign and malignant uterine smooth muscle tumors. Besides, LPD is a hormonal-dependent leiomyoma. After a detailed literature search, we summarized the detailed clinical features and follow-up information of patients with LPD during pregnancy. CONCLUSIONS: This is the first reported LPD case of successful term pregnancy without recurrence, following resection of all visible lesions in a prior pregnancy. LPD is an unusual intermediate between benign and malignant uterine smooth muscle tumors.

Overexpression of PRC1 indicates a poor prognosis in ovarian cancer.

Protein regulator of cytokinesis­1 (PRC1) is a microtubule­associated factor involved in cytokinesis. Recent studies have indicated that PRC1 overexpression is involved in tumorigenesis in multiple types of human cancer. However, the expression, biological functions and the prognostic significance of PRC1 in ovarian cancer have not yet been clarified. In this study, it was confirmed that the PRC1 mRNA and protein expression levels were upregulated in high­grade serous ovarian carcinoma (HGSOC) tissues, particularly in patients without breast cancer susceptibility gene (BRCA) pathogenic mutations. PRC1 overexpression contributed to drug resistance, tumor recurrence and a poor prognosis. The findings also indicated that PRC1 knockdown decreased the proliferation, metastasis and multidrug resistance of ovarian cancer cells in vitro. It was also demonstrated that forkhead box protein M1 (FOXM1) regulated the mRNA and protein expression of PRC1. Dual­luciferase reporter assay and rescue assay confirmed that PRC1 was a direct crucial downstream target of FOXM1. On the whole, the findings of this study confirmed that PRC1 was a major prognostic factor of HGSOC and a promising therapeutic biomarker for the treatment of ovarian cancer.

Peritoneal cancer after bilateral mastectomy, hysterectomy, and bilateral salpingo-oophorectomy with a poor prognosis: A case report and review of the literature.

BACKGROUND: Primary peritoneal cancer (PPC) patients with BRCA mutations have a good prognosis; however, for patients with BRCA mutations who are diagnosed with PPC after prophylactic salpingo-oophorectomy (PSO), the prognosis is poor, and survival information is scarce. CASE SUMMARY: We treated a 56-year-old woman with PPC after bilateral mastectomy, hysterectomy, and bilateral salpingo-oophorectomy. This patient had primary drug resistance and died 12 mo after the diagnosis of PPC. The genetic test performed on this patient indicated the presence of a germline BRCA1 mutation. We searched the PubMed, Scopus, and Cochrane databases and extracted studies of patients with BRCA mutations who developed PPC after PSO. After a detailed literature search, we found 30 cases, 7 of which had a history of breast cancer, 14 of which had no history of breast cancer, and 9 of which had an unknown history. The average age of PSO patients was 48.86 years old (range, 31-64 years). The average time interval between the diagnosis of PPC and preventive surgery was 61.03 mo (range, 12-292 mo). The 2-year survival rate for this patient population was 78.26% (18/23), the 3-year survival rate was 50.00% (9/18), and the 5-year survival rate was 6.25% (1/16). CONCLUSION: Patients with BRCA mutations who are diagnosed with PPC after preventative surgery have a poor prognosis. Prevention measures and treatments for these patients need more attention.

The role of low density lipoprotein receptor-related protein 11 as a tumor promoter in cervical cancer.

BACKGROUND: It is unclear whether low density lipoprotein receptor-related protein 11 (LRP11), a newly found lipoprotein receptor regulatory protein, has the carcinogenic effects in cervical cancer. METHODS: Bioinformatics analysis, immunohistochemical (IHC) staining and evaluation, cell proliferation assay, flow cytometry, transwell migration and invasion assays, Western blotting, growth of LRP11-silenced cells in athymic nude mice were performed in this research. RESULTS: We found that LRP11 expression was higher in high-grade squamous intraepithelial lesions (HSIL) and cervical cancer tissue than in normal cervix, and high expression of LRP11 was associated with differentiation degree (P=0.0266), indicating poor prognosis (P=0.0210). The silencing of LRP11 in SiHa and CaSki cell lines inhibited cell proliferation, reduced migration and invasion and suppressed cell growth in nude mice, which possibly related to cell cycle protein regulation of CDK 2/4, cyclin D1/E1, MMP-2/9, and VEGF. Furthermore, LRP11 showed substantial positive correlation with P16 in vivo and in vitro. CONCLUSION: LRP11 plays important roles in proliferation, migration and invasion, with the potential to be a useful prognostic marker and therapeutic target for patients with HSIL and cervical cancer.

Determination of Clinical Cut-Off Values for Serum Cystatin C Levels to Predict Ischemic Stroke Risk.

BACKGROUND: The association between cystatin C and risk of ischemic stroke is inconsistent and the cut-off values of cystatin C are diverse in different articles. We aimed to investigate the association between cystatin C levels and the development of ischemic stroke and to explore the clinical cut-off values of serum cystatin C levels for ischemic stroke. METHODS: This prospective cohort study included 7658 participants from the China Health and Retirement Longitudinal Study who were free of cardiovascular diseases and cancer at baseline. A decision-tree model was used to find reasonable cut-off values for cystatin C levels. Logistic regression models were used to analyze the association between different levels of cystatin C and the risk of ischemic stroke. RESULTS: The whole cohort was divided into the following 3 groups according to the decision tree: group-low (<.901 mg/L), group-moderate (.901∼1.235 mg/L), and group-high (>1.235 mg/L). After 4 years of follow-up, we identified 156 cases of ischemic stroke. After adjusting for potential confounding factors, the odds ratios (95% confidence intervals) of ischemic stroke were 1.637 (1.048-2.556) for group-moderate and 2.326 (1.285-4.210) for group-high) compared with the low group of cystatin C. Subgroup analyses showed that the association between cystatin C levels and the incidence of ischemic stroke was more pronounced in males or old people than in females or young people. CONCLUSIONS: We found 2 suitable cut-off values for serum cystatin C levels and found that high levels of cystatin C were associated with an increased risk of ischemic stroke.

BRCA mutation frequency and clinical features of ovarian cancer patients: A report from a Chinese study group.

AIM: Subjects with germline BRCA1/2 mutations (gBRCAm) have an increased risk of developing breast cancer and ovarian cancer. At present, knowledge of BRCA1/2 mutation frequency in Chinese patients with ovarian cancer is still insufficient, and the detailed clinical information of these patients is poorly understood. METHODS: A total of 547 unselected ovarian cancer patients were enrolled, and their gBRCAm status was detected. Clinical characteristics including age, personal and family history, histopathologic diagnosis, carbohydrate antigen 125 (CA-125) level, ascites, Federation International of Gynecology and Obstetrics (FIGO) stage, residual lesions, platinum sensitivity, recurrence interval and survival information were collected. Accurate assessments of disease response were based on the RECIST standard or CA-125 level. RESULTS: In 547 patients with ovarian cancer, we detected 129 (23.6%) patients with pathogenic mutations, 84 patients with BRCA1 mutations (15.4%) and 45 patients with BRCA2 mutations (8.2%). Twenty-five novel mutations were identified, and the mutation of BRCA1, c.5470_5477del8, was the most common mutation in this study. BRCA1/2 mutations were significantly associated with age; personal and family history; FIGO stage; secondary recurrence interval; sensitivity to platinum in 1st, 2nd and 3rd line treatment; and response to doxorubicin liposomes. Patients with BRCA1/2 mutations showed significant advantages in 3- and 5-year survival rates but no advantage in long-term survival. CONCLUSION: BRCA1/2 mutation prevalence in Chinese ovarian cancer patients is higher than the international rate. We recommend BRCA1/2 testing for patients with family histories and personal histories of malignancy and genetic counseling for cancer in healthy people with high-risk family histories.

Roles of B7-H3 in Cervical Cancer and Its Prognostic Value.

B7-H3, which has been reported to be a co-regulatory ligand of the B7 family, can suppress T cell-mediated immunity and has also been reported to be expressed in many malignancies. In this study, we found that B7-H3 was primarily expressed in the cytoplasm of cervical cancer cells and was associated with deep stromal invasion (P=0.0013). The disease-free survival data showed that cervical cancer patients whose tumours were positive for B7-H3 expression had higher mortality rates compared with patients whose tumours lacked B7-H3 expression (P=0.0317), representing an advantage over P16 (P=0.3486). In contrast, the level of serum B7-H3 was low in cases of cervical intraepithelial neoplasia and cervical cancer. The silencing of B7-H3 in the SiHa, CaSki and H8 cell lines inhibited cell proliferation and enhanced apoptosis, while the over-expression of B7-H3 in HeLa cells showed inverse changes. These changes were partially due to the regulation of cell cycle- and apoptosis-related proteins, such as E2F, P21, P16, PARP-1, Caspase-8, Bax, Bcl-2 and Bcl-xl. The results of in vivo experiments revealed that the knockdown of B7-H3 in tumour cells suppressed SiHa cell growth in nude mice. Overall, B7-H3 is involved in the development and progression of cervical intraepithelial neoplasia and cervical cancer through its effects on the cell cycle and apoptosis, which are mediated via the E7/Rb pathway. B7-H3 also has the potential to be a useful prognostic marker for patients with cervical cancer.

Negative roles of B7-H3 and B7-H4 in the microenvironment of cervical cancer.

Although persistent human papilloma virus (HPV) infection exerts a crucial influence on cervical carcinogenesis, other factors are also involved in its development, such as intraepithelial lesions and cervical cancer. B7-H3 and B7-H4, which have been reported to be co-regulatory ligands in the B7 family, had been found to be overexpressed in cervical cancer and correlated with adverse clinicopathological features and poor prognosis in our previous studies. In this study, we sought to explore the effects of B7-H3 and B7-H4 on the cervical microenvironment. Among several immune cytokines, interleukin-10 (IL-10) and transforming growth factor (TGF) ß1 stand out as important immunosuppressive factors. Our studies found that IL-10 expression increased with pathological change levels and significantly correlated with cervical cancer differentiation (P < 0.05). TGF-ß1 correlated with lymph node metastasis (LNM) (P < 0.01). Expression of B7-H3 and B7-H4 positively correlated with the expression of IL-10 and TGF-ß1. After co-culture, we found that overexpression of B7-H3 and B7-H4 in cervical cancer cell lines resulted in activation of the cell cycle and decreased apoptosis of U-937 cells. In addition, the contents of IL-10 and TGF-ß1, as well as their protein expression levels, increased in co-culture supernatants in U-937 cells, suggesting regulation by the p-JAK2/STAT3 pathway. The in vivo results demonstrated that with the increasing expression of B7-H3/B7-H4, the expression of IL-10 and TGF-ß1 also increased significantly. Overall, the expression of B7-H3 and B7-H4 favored an immunosuppressive microenvironment by promoting the production of IL-10 and TGF-ß1, thereby resulting in progression of cervical carcinogenesis.

Gene editing as a promising approach for respiratory diseases.

Respiratory diseases, which are leading causes of mortality and morbidity in the world, are dysfunctions of the nasopharynx, the trachea, the bronchus, the lung and the pleural cavity. Symptoms of chronic respiratory diseases, such as cough, sneezing and difficulty breathing, may seriously affect the productivity, sleep quality and physical and mental well-being of patients, and patients with acute respiratory diseases may have difficulty breathing, anoxia and even life-threatening respiratory failure. Respiratory diseases are generally heterogeneous, with multifaceted causes including smoking, ageing, air pollution, infection and gene mutations. Clinically, a single pulmonary disease can exhibit more than one phenotype or coexist with multiple organ disorders. To correct abnormal function or repair injured respiratory tissues, one of the most promising techniques is to correct mutated genes by gene editing, as some gene mutations have been clearly demonstrated to be associated with genetic or heterogeneous respiratory diseases. Zinc finger nucleases (ZFN), transcription activator-like effector nucleases (TALEN) and clustered regulatory interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) systems are three innovative gene editing technologies developed recently. In this short review, we have summarised the structure and operating principles of the ZFNs, TALENs and CRISPR/Cas9 systems and their preclinical and clinical applications in respiratory diseases.

Potential Roles of Amiloride-Sensitive Sodium Channels in Cancer Development.

The ENaC/degenerin ion channel superfamily includes the amiloride-sensitive epithelial sodium channel (ENaC) and acid sensitive ionic channel (ASIC). ENaC is a multimeric ion channel formed by heteromultimeric membrane glycoproteins, which participate in a multitude of biological processes by mediating the transport of sodium (Na(+)) across epithelial tissues such as the kidney, lungs, bladder, and gut. Aberrant ENaC functions contribute to several human disease states including pseudohypoaldosteronism, Liddle syndrome, cystic fibrosis, and salt-sensitive hypertension. Increasing evidence suggests that ion channels not only regulate ion homeostasis and electric signaling in excitable cells but also play important roles in cancer cell behaviors such as proliferation, apoptosis, invasion, and migration. Indeed, ENaCs/ASICs had been reported to be associated with cancer characteristics. Given their cell surface localization and pharmacology, pharmacological strategies to target ENaC/ASIC family members may be promising cancer therapeutics.

Age-related cataract, cataract surgery and subsequent mortality: a systematic review and meta-analysis.

PURPOSE: Changes in lens may reflect the status of systemic health of human beings but the supporting evidences are not well summarized yet. We aimed to determine the relationship of age-related cataract, cataract surgery and long-term mortality by pooling the results of published population-based studies. METHODS: We searched PubMed and Embase from their inception till March, 2014 for population-based studies reporting the associations of any subtypes of age-related cataract, cataract surgery with all-cause mortality. We pooled the effect estimates (hazards ratios [HRs]) under a random effects model. RESULTS: Totally, we identified 10 unique population-based studies including 39,659 individuals at baseline reporting the associations of any subtypes of cataract with all-cause mortality from 6 countries. The presence of any cataract including cataract surgery was significantly associated with a higher risk of death (pooled HR: 1.43, 95% CI, 1.21, 2.02; P<0.001; I(2) = 64.2%). In the meta-analysis of 9 study findings, adults with nuclear cataract were at higher risks of mortality (pooled HR: 1.55, 95% CI, 1.17, 2.05; P = 0.002; I(2) = 89.2%). In the meta-analysis of 8 study findings, cortical cataract was associated with higher risks of mortality (pooled HR: 1.26, 95% CI, 1.12, 1.42; P<0.001, I(2) = 29.7%). In the meta-analysis of 6 study findings, PSC cataract was associated with higher risks of mortality (pooled HR: 1.37, 95% CI, 1.04, 1.80; P = 0.03; I(2) = 67.3%). The association between cataract surgery and mortality was marginally non-significant by pooling 8 study findings (pooled HR: 1.27, 95% CI, 0.97, 1.66; P = 0.08; I(2)= 76.6%). CONCLUSIONS: All subtypes of age-related cataract were associated with an increased mortality with nuclear cataract having the strongest association among the 3 cataract subtypes. However, cataract surgery was not significantly related to mortality. These findings indicated that changes in lens may serve as markers for ageing and systemic health in general population.

A novel role of proteasomal ß1 subunit in tumorigenesis.

p27Kip1 is a key cell-cycle regulator whose level is primarily regulated by the ubiquitin-proteasome degradation pathway. Its ß1 subunit is one of seven ß subunits that form the ß-ring of the 20S proteasome, which is responsible for degradation of ubiquitinated proteins. We report here that the ß1 subunit is up-regulated in oesophageal cancer tissues and some ovarian cancer cell lines. It promotes cell growth and migration, as well as colony formation. ß1 binds and degrades p27Kip1directly. Interestingly, the lack of phosphorylation at Ser158 of the ß1 subunit promotes degradation of p27Kip1. We therefore propose that the ß1 subunit plays a novel role in tumorigenesis by degrading p27Kip1.