Primary cilia: Structure, dynamics, and roles in cancer cells and tumor microenvironment.

Despite the initiation of tumor arises from tumorigenic transformation signaling in cancer cells, cancer cell survival, invasion, and metastasis also require a dynamic and reciprocal association with extracellular signaling from tumor microenvironment (TME). Primary cilia are the antenna-like structure that mediate signaling sensation and transduction in different tissues and cells. Recent studies have started to uncover that the heterogeneous ciliation in cancer cells and cells from the TME in tumor growth impels asymmetric paracellular signaling in the TME, indicating the essential functions of primary cilia in homeostasis maintenance of both cancer cells and the TME. In this review, we discussed recent advances in the structure and assembly of primary cilia, and the role of primary cilia in tumor and TME formation, as well as the therapeutic potentials that target ciliary dynamics and signaling from the cells in different tumors and the TME.

Single-cell RNA sequencing reveals species-specific time spans of cell cycle transitions in early oogenesis.

Oogenesis is a highly regulated process and its basic cellular events are evolutionarily conserved. However, the time spans of oogenesis differ substantially among species. To explore these interspecies differences in oogenesis, we performed single-cell RNA-sequencing on mouse and monkey female germ cells and downloaded the single-cell RNA-sequencing data of human female germ cells. The cell cycle analyses indicate that the period and extent of cell cycle transitions are significantly different between the species. Moreover, hierarchical clustering of critical cell cycle genes and the interacting network of cell cycle regulators also exhibit distinguished patterns across species. We propose that differences in the regulation of cell cycle transitions may underlie female germ cell developmental allochrony between species. A better understanding of the cell cycle transition machinery will provide new insights into the interspecies differences in female germ cell developmental time spans.

Kinetochore scaffold 1 regulates SAC function during mouse oocyte meiotic maturation.

Precise regulation of chromosome separation through spindle assembly checkpoint (SAC) during oocyte meiosis is critical for mammalian reproduction. The kinetochore plays an important role in the regulation of SAC through sensing microtubule tension imbalance or missing microtubule connections. Here, we report that kinetochore scaffold 1 (KNL1, also known as CASC5), an outer kinetochore protein, plays a critical role in the SAC function of mouse oocytes. KNL1 localized at kinetochores from GVBD to the MII stage, and microinjection of KNL1-siRNA caused accelerated metaphase-anaphase transition and premature first meiosis completion, producing aneuploid eggs. The SAC was prematurely silenced in the presence of unstable kinetochore-microtubule attachments and misaligned chromosomes in KNL1-depleted oocytes. Additionally, KNL1 and MPS1 had a synergistic effect on the activation and maintenance of SAC. Taken together, our results suggest that KNL1, as a kinetochore platform protein, stabilizes SAC to ensure timely anaphase entry and accurate chromosome segregation during oocyte meiotic maturation.

Toxic effects of AZD1208 on mouse oocytes and its possible mechanisms.

AZD1208, a pan-inhibitor that can effectively inhibit PIM kinase, is used for the treatment of advanced solid tumors and malignant lymphomas. Numerous studies have proved its curative effects while its potential cellular toxicity on reproduction was still little known. In this study, we investigated the toxic effects of AZD1208 on mouse oocytes. The results showed that AZD1208 treatment did not affect meiotic resumption, but postponed oocyte maturation as indicated by delayed first polar body extrusion. Further mechanistic study showed that AZD1208 treatment delayed spindle assembly. In addition, we found that oocytes treated with AZD1208 showed mitochondrial dysfunction. Abnormal mitochondrial clusters with decreased mitochondrial membrane potential were observed in oocytes during incubation in vitro. Moreover, increased oxidative stress was observed by testing the level of reactive oxygen species. In summary, our results suggest that AZD1208 treatment influences oocyte meiotic progression by causing mitochondrial dysfunctions and subsequent delayed spindle assembly.

CtIP regulates G2/M transition and bipolar spindle assembly during mouse oocyte meiosis.

CtBP-interacting protein (CtIP) is known for its multifaceted roles in DNA repair and genomic stability, directing the homologous recombination-mediated DNA double-stranded break (DSBs) repair pathway via DNA end resection, an essential error-free repair process vital for genome stability. Mammalian oocytes are highly prone to DNA damage accumulation due to prolonged G2/prophase arrest. Here, we explore the functions of CtIP in meiotic cell cycle regulation via a mouse oocyte model. Depletion of CtIP by siRNA injection results in delayed germinal vesicle breakdown and failed polar body extrusion. Mechanistically, CtIP deficiency increases DNA damage and decreases the expression and nuclear entry of CCNB1, resulting in marked impairment of meiotic resumption, which can be rescued by exogenous CCNB1 overexpression. Furthermore, depletion of CtIP disrupts MTOCs coalescence at spindle poles as indicated by failed accumulation of γ-tubulin, p-Aurora kinase A, Kif2A, and TPX2, leading to abnormal spindle assembly and prometaphase arrest. These results provide valuable insights into the important roles of CtIP in the G2/M checkpoint and spindle assembly in mouse oocyte meiotic cell cycle regulation.

NLRP14 Safeguards Calcium Homeostasis via Regulating the K27 Ubiquitination of Nclx in Oocyte-to-Embryo Transition.

Sperm-induced Ca2+ rise is critical for driving oocyte activation and subsequent embryonic development, but little is known about how lasting Ca2+ oscillations are regulated. Here it is shown that NLRP14, a maternal effect factor, is essential for keeping Ca2+ oscillations and early embryonic development. Few embryos lacking maternal NLRP14 can develop beyond the 2-cell stage. The impaired developmental potential of Nlrp14-deficient oocytes is mainly caused by disrupted cytoplasmic function and calcium homeostasis due to altered mitochondrial distribution, morphology, and activity since the calcium oscillations and development of Nlrp14-deficient oocytes can be rescued by substitution of whole cytoplasm by spindle transfer. Proteomics analysis reveal that cytoplasmic UHRF1 (ubiquitin-like, containing PHD and RING finger domains 1) is significantly decreased in Nlrp14-deficient oocytes, and Uhrf1-deficient oocytes also show disrupted calcium homeostasis and developmental arrest. Strikingly, it is found that the mitochondrial Na+ /Ca2+ exchanger (NCLX) encoded by Slc8b1 is significantly decreased in the Nlrp14mNull oocyte. Mechanistically, NLRP14 interacts with the NCLX intrinsically disordered regions (IDRs) domain and maintain its stability by regulating the K27-linked ubiquitination. Thus, the study reveals NLRP14 as a crucial player in calcium homeostasis that is important for early embryonic development.

OTSSP167 leads to follicular dysplasia and negatively affects oocyte quality in mice.

OTSSP167 is an anti-tumor drug significantly inhibiting tumor growth in xenotransplantation studies using mouse breast, lung, prostate, and pancreatic cancer cell lines. Its phase I clinical trial has been completed, indicating its great potential for future treatment of solid tumors. However, its drug-related adverse effects on reproductive systems have not yet been reported. In this study, we evaluated the effects of OTSSP167 on reproduction of female mice by determining oocyte quality and follicular development. We selected four-week-old female ICR mice for a 21-day intraperitoneal injection of OTSSP167 at a dose of 5 mg/kg/d. We found that OTSSP167 could block the meiotic process of oocytes, leading to a decrease in oocyte maturation and ovulated oocyte numbers, as well as a decrease in the quality of oocytes. The results showed that OTSSP167 treatment caused disordered spindle assembly, decreased mitochondria membrane potential, and increased accumulation of reactive oxygen species in oocytes. Further investigation showed that OTSSP167 induced DNA double-strand breaks, as indicated by increased levels of γH2AX in oocytes of primordial follicles and granulosa cells of growing follicles, which induced follicular atresia and decreased the numbers of follicles at various growing stages. Our study suggests that OTSSP167 treatment may have serious effects on the ovary and consequences for female cancer patients, providing strong evidence for the necessity of protecting female fertility in clinical OTSSP167 trials.

The Cyclin B2/CDK1 Complex Conservatively Inhibits Separase Activity in Oocyte Meiosis II.

Recently, we have reported that the cyclin B2/CDK1 complex regulates homologous chromosome segregation through inhibiting separase activity in oocyte meiosis I, which further elucidates the compensation of cyclin B2 on cyclin B1's function in meiosis I. However, whether cyclin B2/CDK1 complex also negatively regulates separase activity during oocyte meiosis II remains unknown. In the present study, we investigated the function of cyclin B2 in meiosis II of oocyte. We found that stable cyclin B2 expression impeded segregation of sister chromatids after oocyte parthenogenetic activation. Consistently, stable cyclin B2 inhibited separase activation, while introduction of non-phosphorylatable separase mutant rescued chromatid separation in the stable cyclin B2-expressed oocytes. Therefore, the cyclin B2/CDK1 complex conservatively regulates separase activity via inhibitory phosphorylation of separase in both meiosis I and meiosis II of mouse oocyte.

Study on Relationships of Tumor Status and Gene Polymorphism With Blood Concentration of MTX and Toxicities in 63 Pediatric Mature B Cell Lymphoma in Chinese Population.

OBJECTIVE: This study investigated the relationships of tumor status (stage, renal involvement, bone marrow status, bulky disease, liver function), tumor gene polymorphism, and methotrexate (MTX) dosage (stratified by treatment group) with blood MTX levels and adverse reactions (ADR). METHODS: We retrospectively reviewed 63 mature B cell lymphoma patients who were treated in our center. Genotyping of the MTHFR 677 and SLCO1B1 genes was carried out, and the relationships between tumor status, polymorphism of the genes, MTX level, and ADR were analyzed. RESULTS: Altogether, 63 children were included. The mean blood MTX concentration was 0.25 ± 0.2 umol/L at 45 h. Liver dysfunction and bulky disease were both correlated with MTX level (both P < 0.05). ADRs were higher among patients with blood MTX > 0.5 mmol/l at 45 h than for the groups with lower blood MTX. The MTHFR 677 CT genotype was correlated with liver function damage (P = 0.04); the rs11045879 locus CC genotype of SLCO1B1, stage IV, and bulky disease at the time of diagnosis were correlated with 4° neutropenia (P < 0.05). Stage IV, bulky disease, leukemia stage at the time of diagnosis, and C2 treatment group were correlated with severe anemia (P < 0.05). Stage IV, bulky disease, leukemia stage, renal invasion at the time of diagnosis, and C2 treatment group were associated with severe thrombocytopenia (P < 0.05). Bulky disease and renal invasion at the time of diagnosis were associated with severe mucositis and severe infection (P < 0.05). CONCLUSION: Taken together, our data demonstrate that gene polymorphism, MTX levels, tumor status, and treatment group might be useful to optimize MTX therapy and estimate toxicity.

Cell Division Cycle 5-Like Regulates Metaphase-to-Anaphase Transition in Meiotic Oocyte.

The quality of oocytes is a vital factor for embryo development. Meiotic progression through metaphase I usually takes a relatively long time to ensure correct chromosome separation, a process that is critical for determining oocyte quality. Here, we report that cell division cycle 5-like (Cdc5L) plays a critical role in regulating metaphase-to-anaphase I transition during mouse oocyte meiotic maturation. Knockdown of Cdc5L by small interfering RNA injection did not affect spindle assembly but caused metaphase I arrest and subsequent reduced first polar body extrusion due to insufficient anaphase-promoting complex/cyclosome activity. We further showed that Cdc5L could also directly interact with securin, and Cdc5L knockdown led to a continuous high expression level of securin, causing severely compromised meiotic progression. The metaphase-to-anaphase I arrest caused by Cdc5L knockdown could be rescued by knockdown of endogenous securin. In summary, we reveal a novel role for Cdc5L in regulating mouse oocyte meiotic progression by interacting with securin.

Gefitinib reduces oocyte quality by disturbing meiotic progression.

Gefitinib is a first-line anti-cancer drug for the treatment of advanced non-small cell lung cancer (NSCLC). It has been reported that gefitinib can generate several drug-related adverse effects, including nausea, peripheral edema, decreased appetite and rash. However, the reproductive toxicity of gefitinib has not been clearly defined until now. Here we assessed the effects of gefitinib on oocyte quality by examining the critical events and molecular changes of oocyte maturation. Gefitinib at 1, 2, 5 or 10 µM concentration was added to culture medium (M2). We found that gefitinib at its median peak concentration of 1 µM did not affect oocyte maturation, but 5 µM gefitinib severely blocked oocyte meiotic progression as indicated by decreased rates of germinal vesicle breakdown (GVBD) and polar body extrusion (PBE). We further showed that gefitinib treatment increased phosphorylation of CDK1 at the site of Try15, inhibited cyclin B1 entry into the nucleus, and disrupted normal spindle assembly, chromosome alignment and mitochondria dynamics, finally leading to the generation of aneuploidy and early apoptosis of oocytes. Our study reported here provides valuable evidence for reproductive toxicity of gefitinib administration employed for the treatment of cancer patients.