Imaging features that distinguish pure ductal carcinoma in situ (DCIS) from DCIS with microinvasion

Patients with ductal carcinoma in situ with microinvasion (DCISM) have worse cancer-specific survival, disease-free survival and overall survival, and a higher mortality rate compared with patients with ductal carcinoma in situ (DCIS). Distinguishing DCISM from DCIS via preoperative imaging could help to predict the prognosis of patients. The present study compared the sonographic and mammographic features of patients with DCIS and DCISM. A total of 147 women (94 patients with DCIS and 53 patients with DCISM) were retrospectively included. The sonographic lesions were classified as either masses or non-mass abnormalities. The lesions observed on mammography were classified as calcifications only, mass, asymmetry or architectural distortion. Statistical comparisons were performed using the Mann-Whitney U test, χ² test, Fisher's exact test and multiple logistic regression analysis. Univariate and multivariate analyses showed that the presence of calcifications (P=0.038) and vascularity (P=0.025) on sonography were associated with DCISM. Furthermore, a lager distribution of calcifications was associated with a higher likelihood of DCISM (P=0.002). In conclusion, the presence of calcifications and vascularity on sonography or a lager distribution of calcifications on mammography may suggest DCISM.

Does establishing a preoperative nomogram including ultrasonographic findings help predict the likelihood of malignancy in patients with microcalcifications?

BACKGROUND

Mammography (MG) is highly sensitive for detecting microcalcifications, but has low specificity. This study investigates whether establishing a preoperative nomogram including ultrasonographic findings can help predict the likelihood of malignancy in patients with mammographic microcalcification.

METHODS

Between May 2012 and January 2017, 475 patients with suspicious microcalcifications detected on MG underwent ultrasonography (US). The χ² test was used to screen risk factors among the variables. Then, a multivariate logistic regression analysis was performed to identify independent predictors of malignant microcalcifications. A mammographic nomogram (M nomogram) and mammographic-ultrasonographic nomogram (M-U nomogram) were established based on multivariate logistic regression models. The discriminatory ability and clinical utility of both nomograms were compared by the receiver operating characteristics curve and decision curve analysis. The calibration ability was evaluated using a calibration curve.

RESULTS

Among the cases, 68.2% (324/475) were pathologically diagnosed as breast cancer and 31.8% (151/475) were benign lesions. Based on multivariate logistic regression analysis, age, clinical manifestation, morphology and distribution of microcalcifications on MG and lesions associated with microcalcifications on US were confirmed as independent predictors of malignant microcalcifications. In terms of discrimination ability, the C-index of the M-U nomogram was significantly higher than that of the M nomogram (0.917 vs 0.897, p = 0.006). The bias-corrected curve was close to the ideal line in the calibration curve. Decision curve analysis suggested that the M-U nomogram was superior to M nomogram.

CONCLUSIONS

Combining mammographic parameters with ultrasonographic findings in a nomogram provided better performance than an M nomogram alone, especially for dense breasts, which suggests the value of ultrasonographic finding for individualized prediction of malignancy in patients with microcalcifications.

Impaired neurodevelopmental pathways in autism spectrum disorder: a review of signaling mechanisms and crosstalk

Background

The development of an autistic brain is a highly complex process as evident from the involvement of various genetic and non-genetic factors in the etiology of the autism spectrum disorder (ASD). Despite being a multifactorial neurodevelopmental disorder, autistic patients display a few key characteristics, such as the impaired social interactions and elevated repetitive behaviors, suggesting the perturbation of specific neuronal circuits resulted from abnormal signaling pathways during brain development in ASD. A comprehensive review for autistic signaling mechanisms and interactions may provide a better understanding of ASD etiology and treatment.

Main body

Recent studies on genetic models and ASD patients with several different mutated genes revealed the dysregulation of several key signaling pathways, such as WNT, BMP, SHH, and retinoic acid (RA) signaling. Although no direct evidence of dysfunctional FGF or TGF-β signaling in ASD has been reported so far, a few examples of indirect evidence can be found. This review article summarizes how various genetic and non-genetic factors which have been reported contributing to ASD interact with WNT, BMP/TGF-β, SHH, FGF, and RA signaling pathways. The autism-associated gene ubiquitin-protein ligase E3A (UBE3A) has been reported to influence WNT, BMP, and RA signaling pathways, suggesting crosstalk between various signaling pathways during autistic brain development. Finally, the article comments on what further studies could be performed to gain deeper insights into the understanding of perturbed signaling pathways in the etiology of ASD.

Conclusion

The understanding of mechanisms behind various signaling pathways in the etiology of ASD may help to facilitate the identification of potential therapeutic targets and design of new treatment methods.

Does the radiologist need to rescan the breast lesion to validate the final BI-RADS US assessment made on the static images in the diagnostic setting?

Purpose: To assess whether radiologist needs to rescan the breast lesion to validate the final American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) ultrasonography (US) assessment made on the static images in the diagnostic setting.

Patients and methods: Image data on 1,070 patients with 1,070 category 3–5 breast lesions with a pathological diagnosis scanned between January and June 2016 were included. Both real-time and static image assessments were acquired for each lesion. The diagnostic performance was evaluated by receiver operating characteristic (ROC) curves. The positive predictive values (PPVs) of each category in the two groups were calculated according to the ACR BI-RADS manual and compared. Kappas were determined for agreement on two assessment approaches.

Results: The sensitivity, specificity, PPV, and negative predictive value for real-time US were 98.9%, 58.2%, 44.8% and 99.4%, and for static images were 98.9%, 57.1%, 44.1% and 99.3%, respectively. The performance of the two groups was not significantly different (areas under ROCs: 0.786 vs 0.780, P=0.566) if the final assessment was only dichotomized as negative (category 3) and positive (categories 4 and 5). All PPVs of each category for each assessment were within the reference range provided by the ACR in 2013 except subcategory 4B (reference range: >10% and ≤50%) of static image evaluation, which was also significantly higher than that of real-time assessment (54.8% vs 40.7%, P=0.037). The overall agreement of the two approaches was moderate (κ=0.43–0.56 according to different detailed assessment).

Conclusion: Both static image and real-time assessment had similar diagnostic performance if only the treatment recommendations were considered, that is, follow-up or biopsy. However, as for subcategory 4B lesions without obviously benign or malignant US features, real-time scanning by the interpreter is recommended to obtain a more accurate BI-RADS assessment after assessing static images.

Wnt signaling in orofacial clefts: crosstalk, pathogenesis and models

Diverse signaling cues and attendant proteins work together during organogenesis, including craniofacial development. Lip and palate formation starts as early as the fourth week of gestation in humans or embryonic day 9.5 in mice. Disruptions in these early events may cause serious consequences, such as orofacial clefts, mainly cleft lip and/or cleft palate. Morphogenetic Wnt signaling, along with other signaling pathways and transcription regulation mechanisms, plays crucial roles during embryonic development, yet the signaling mechanisms and interactions in lip and palate formation and fusion remain poorly understood. Various Wnt signaling and related genes have been associated with orofacial clefts. This Review discusses the role of Wnt signaling and its crosstalk with cell adhesion molecules, transcription factors, epigenetic regulators and other morphogenetic signaling pathways, including the Bmp, Fgf, Tgfβ, Shh and retinoic acid pathways, in orofacial clefts in humans and animal models, which may provide a better understanding of these disorders and could be applied towards prevention and treatments.

Neuroprotective effect and mechanism of baicalin on Parkinson's disease model induced by 6-OHDA

OBJECTIVE

This research was aimed to investigate the effects of baicalin on 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease (PD) and the main mechanism of baicalin based on metabolomics.

METHODS

The rat model of PD was induced by 6-OHDA. The protective effects of baicalin on rat model of PD were evaluated by open field test and rotarod test. The anti-PD efficacy of baicalin was evaluated by examining the morphologic changes of neurons and the level of monoamine neurotransmitters in the striatum, the number and morphology of tyrosine hydroxylase (TH)-positive neurons, and oxidative stress. Combined with metabolomics methods, the pharmacodynamic mechanism of baicalin on PD pathogenesis was also explored.

RESULTS

Baicalin treatment improved the rod time and voluntary movement in rat model of PD (P<0.05) by the open field test and rotarod test. In addition, baicalin also protected from oxidative stress injury (P<0.05), and regulated the content of monoamine neurotransmitters dopamine, 3,4-dihydroxyphenylacetic acid, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid (P<0.05) and the number and morphology of TH-positive cells in 6-OHDA-induced PD model rats. By metabolomics, multivariate statistical analysis, and receiver operating characteristic curve analysis, we found that two metabolites N-acetyl aspartic acid and glutamic acid had a good diagnostic value. Quantitative analysis of metabolites showed a regulatory function of baicalin.

CONCLUSION

Baicalin has significant protective effect on 6-OHDA-induced PD rats, which may play a protective role through an antioxidant, promoting the release of neurotransmitters and regulating the metabolism of N-acetyl aspartate and glutamate.

CsTFL1b may regulate the flowering time and inflorescence architecture in cucumber (Cucumis sativus L.)

Cucumber is an important vegetable with indeterminate growth habit which is beneficial to its yield. In this study, we cloned the TFL1 homolog CsTFL1b in cucumber. CsTFL1b shares highly sequence similarity to TFL1 from Arabidopsis and has conservative histidine amino acid residue which is necessary for TFL1 function. However, phylogenetic analysis suggested that cucurbits TFL1s (CsTFL1b of cucumber and CmTFL1 of melon) formed a subclade which is far from the AtTFL1 in Arabidopsis or CEN in Antirrhinum. CsTFL1b was highest expressed in male flower but barely expressed in SAM which was different from TFL1 in Arabidopsis with highly transcription accumulation in SAM and CsTFL1b was located in nucleus and cytoplasm. Upon ectopic expression of CsTFL1b in Arabidopsis, the flowering time of transgenic plants was significantly delayed in both wild type and tfl1-11 mutant background but the terminal flower phenotype of tfl1-11 mutant was partially rescued. These results may underlie the discrepant function of CsTFL1b in cucumber from that in Arabidopsis.

CsSPL functions as an adaptor between HD-ZIP III and CsWUS transcription factors regulating anther and ovule development in Cucumis sativus (cucumber)

Anther and ovule genesis preconditions crop fertilization and fruit production; however, coordinative regulation of anther and ovule development and underlying molecular pathways remain largely elusive. Here, we found that SPOROCYTELESS (SPL)/NOZZLE (NZZ) expression was nearly abolished in a Cucumis sativus (cucumber) mutant with severely defective anther and ovule development. CsSPL was expressed specifically in the developing anthers and ovules. Knock-down of CsSPL reduced male and female fertility with malformed pollen and suppressed ovule development. Importantly, CsSPL directly interacted with CsWUS (WUSCHEL) in the nucellus and YABBY family genes in integuments, and positively regulated CsWUS expression, meanwhile the HD-ZIP III gene CsPHB (PHABULOSA), expressed specifically in the nucellus, promoted CsSPL expression by binding to the CsSPL promoter. Thus, CsSPL acts as an adaptor to link CsPHB and CsWUS functioning, underpinning a previously unidentified regulatory pathway orchestrating sex organ development in planta. In addition, auxin accumulation was reduced in the reproductive organs of CsSPL knock-down plants. Biochemical analyses further showed that CsSPL stimulated the expression of AUXIN RESPONSE FACTOR 3 (CsARF3), and was positively regulated by CsARF13 during reproductive organ development, indicating sequential interactions of CsSPL with auxin signaling components in orchestrating anther and ovule development.

CsLFY is required for shoot meristem maintenance via interaction with WUSCHEL in cucumber (Cucumis sativus)

Cucumber (Cucumis sativus) is an agronomically important vegetable with indeterminant growth habit, in which leaves are produced from the shoot apical meristem (SAM), and unisexual flowers are generated from the leaf axils. LEAFY (LFY) and its homologs have been shown to play important roles in promoting flower development and branching. The LFY homolog gene CsLFY was cloned in cucumber. Molecular biology, developmental biology and biochemical tools were combined to explore the biological function of the LFY homologous gene CsLFY in cucumber. CsLFY was expressed in the SAM, floral meristem and floral organ primordia. Ectopic expression of CsLFY rescued the phenotype of the lfy-5 mutant in Arabidopsis. Knockdown of CsLFY by RNA interference (RNAi) led to defective shoot development and premature discontinuance of leaf initiation in cucumber. Transcription of CsWUS and putative CsLFY target genes including CsAP3 and CUM1 were significantly reduced in the CsLFY-RNAi lines. Further biochemical analyses indicated that CsLFY physically interacts with CsWUS in cucumber. These data suggested that CsLFY has a novel function in regulating shoot meristem maintenance through interaction with CsWUS, and promotes flower development via activation of CsAP3 and CUM1 in cucumber.

Random dopant fluctuations and statistical variability in n-channel junctionless FETs

The influence of random dopant fluctuations on the statistical variability of the electrical characteristics of n-channel silicon junctionless nanowire transistor (JNT) has been studied using three dimensional quantum simulations based on the non-equilibrium Green's function (NEGF) formalism. Average randomly distributed body doping densities of 2 × 10¹⁹, 6 × 10¹⁹ and 1 × 10²⁰ cm^-3 have been considered employing an atomistic model for JNTs with gate lengths of 5, 10 and 15 nm. We demonstrate that by properly adjusting the doping density in the JNT, a near ideal statistical variability and electrical performance can be achieved, which can pave the way for the continuation of scaling in silicon CMOS technology.

Does patient age affect the PPV3 of ACR BI-RADS Ultrasound categories 4 and 5 in the diagnostic setting?

OBJECTIVES

To calculate the positive predictive value of biopsies performed (PPV₃) of the Ultrasound section of the American College of Radiology Breast Imaging Reporting and Data System (ACR BI-RADS US) atlas categories 4 and 5 in different age groups and to determine whether patient age influences the PPV₃ of each category in the diagnosis of breast lesions.

METHODS

We identified 2,433 ACR BI-RADS US categories 4 and 5 lesions with a known pathological diagnosis in 2,433 women. The patients were classified into three age groups (<35, 35-50, and >50 years). The age-related PPV₃ of each category in the three age groups were calculated based on the pathological diagnoses and compared using the chi-squared test.

RESULTS

The overall PPV₃ of each category was within the reference range provided by the ACR in 2013. PPV₃ gradually increased with increasing age in patients with category 4 lesions. PPV₃ in the oldest group with subcategories 4A and 4B lesions were close to or exceeded the reference values.

CONCLUSIONS

PPV₃ and age were significantly associated in patients with category 4 lesions according to the newest edition of ACR BI-RADS US in the diagnostic setting. Closer attention should be given to older patients when assigning a final assessment category.

KEY POINTS

• In patients with category 4 lesions , the likelihood of malignancy is associated with age. • In patients with category 5 lesions, the association is not definite. • Closer attention should be given to older patients in applying the ACR BI-RADS US.

SPG3A gene polymorphisms in hereditary spastic paraplegia

OBJECTIVE

This study aimed to analyze the hereditary spastic paraplegia (HSP)/spastic paraplegia 3A (SPG3A) genomic structure as well as the polymorphisms in SPG3G genomic structure by comparing with the normal subjects.

METHODS

A total of 66 sporadic cases with HSP were collected from April 2014 to September 2016. Genomic DNA extraction was performed, and all coding exons and junction region in the SPG3A gene were sequenced. Genetic mutations were identified and DNA sequence alignment was performed against 80 normal subjects without blood relationship. The polymorphism in SPG3A gene was analyzed.

RESULTS

The coding sequence of the SPG3A gene consisted of 14 exons and two polymorphisms were detected at exons 2 and 3 compared with the normal subjects; one polymorphism was detected at exons 3, 4 and 6, respectively.

CONCLUSION

The two coding exons in the SPG3A gene in normal subjects were polymorphic and highly conservative. The intron consisted of 3 polymorphic coding sequences. Understanding the polymorphism and genetic mutations in the SPG3A gene will contribute to the diagnosis and treatment of HSP.

Rare imaging appearance of adenoid cystic carcinoma of the breast: A case report

Adenoid cystic carcinoma (ACC) of the breast is a rare tumor comprising <0.1% of all breast malignancies. The present study reports the case of a 66-year-old woman who underwent multiple imaging techniques, including mammography, ultrasonography and magnetic resonance imaging (MRI). The patient reported gradual enlargement of a mass in the left breast. Mammography identified a high-density, irregular mass, with nipple retraction. Ultrasonography revealed an irregular, complex cystic and solid mass with an unclear margin in the subareolar region. The internal vascularity was seen on Doppler examination. The lesion on MRI was also mixed cystic and solid, with an irregular shape and irregular margins. The solid part of the lesion appeared heterogeneously isointense on T1-weighted imaging (WI) and a slightly high signal on T2WI, and exhibited internal septations with a low signal on T2WI. Following injection of contrast agent, the enhancement of the solid part was rapid and heterogeneous. The cystic parts of lesion appeared as high-signal on T1WI and T2WI. The tumor infiltrated the left nipple and adjacent skin. The patient underwent a left modified radical mastectomy with axillary lymph node dissection. The pathological examination confirmed the tumor as ACC of the left breast. The axillary lymph nodes were negative for tumor metastasis. Therefore, the differential diagnosis of mixed cystic and solid breast masses with unclear margins and internal septations on T2WI exhibiting delayed enhancement, must include ACC.

Ubiquitin E3 ligase Itch negatively regulates osteoblast function by promoting proteasome degradation of osteogenic proteins

OBJECTIVES

Ubiquitin E3 ligase-mediated protein degradation regulates osteoblast function. Itch, an E3 ligase, affects numerous cell functions by regulating ubiquitination and proteasomal degradation of related proteins. However, the Itch-related cellular and molecular mechanisms by which osteoblast differentiation and function are elevated during bone fracture repair are as yet unknown.

METHODS

We examined the expression levels of E3 ligases and NF-κB members in callus samples during bone fracture repair by quantitative polymerase chain reaction (qPCR) and the total amount of ubiquitinated proteins by Western blot analysis in wild-type (WT) mice. The expression levels of osteoblast-associated genes in fracture callus from Itch knockout (KO) mice and their WT littermates were examined by qPCR. The effect of NF-κB on Itch expression in C2C12 osteoblast cells was determined by a chromatin immunoprecipitation (ChIP) assay.

RESULTS

The expression levels of WW Domain Containing E3 Ubiquitin Protein Ligase 1 (Wwp1), SMAD Specific E3 Ubiquitin Protein Ligase 1 (Smurf1), SMAD Specific E3 Ubiquitin Protein Ligase 2 (Smurf2) and Itch were all significantly increased in the fracture callus of WT mice, which was associated with elevated expression of NF-κB members and total ubiquitinated proteins. Callus tissue isolated from Itch KO mice expressed higher levels of osteoblast-associated genes, including Runx2, a positive regulator of osteoblast differentiation, but osteoclast-associated genes were not increased. Both NF-κB RelA and RelB proteins were found to bind to the NF-κB binding site in the mouse Itch promoter.

CONCLUSIONS

Our findings indicate that Itch depletion may have a strong positive effect on osteoblast differentiation in fracture callus. Thus, ubiquitin E3 ligase Itch could be a potential target for enhancing bone fracture healing.Cite this article: J. Liu, X. Li, H. Zhang, R. Gu, Z. Wang, Z. Gao, L. Xing. Ubiquitin E3 ligase Itch negatively regulates osteoblast function by promoting proteasome degradation of osteogenic proteins. Bone Joint Res 2017;6:154-161. DOI: 10.1302/2046-3758.63.BJR-2016-0237.R1.

Prognostic significance of Ki67 in Chinese women diagnosed with ER+/HER2- breast cancers by the 2015 St. Gallen consensus classification

BACKGROUND

This study evaluated the distribution pattern of the Ki67-labeling index (LI) among patients at a Chinese breast cancer center, and analyzed its prognostic significance in the 2015 St Gallen consensus breast cancer classification, estrogen receptor-positive and human epidermal growth factor receptor 2-negative(ER+/HER2-)subtype.

METHODS

We classified 939 women with ER+/HER2- breast cancer into three groups by Ki67-LI levels, and followed their clinicopathologic characteristics and prognoses.

RESULTS

In the 939 eligible subjects, 342 had Ki67-LI ≤10% (Ki67Low), 281 had Ki67-LI between 10 and 30% (Ki67Medium), and 316 had Ki67-LI ≥30% (Ki67High). Although the Ki67High group had less favorable clinicopathologic factors, the Ki67Medium group's factors varied considerably. Kaplan-Meier estimates showed that disease-free survival(DFS) for the Ki67Medium group was significantly shorter than the Ki67Low group but longer than the Ki67High group. Ki67-LI had independent prognostic significance in multivariate analysis. Other diagnostic factors, including tumor size >2 cm, positive lymph nodes, and grade III disease, were significantly associated with poorer disease-free survival only in the Ki67Medium group.

CONCLUSIONS

For patients with ER+/HER2- breast cancer, we confirmed three distinct risk patterns by Ki67-LI levels according to the 2015 St Gallen consensus. For patients with clearly low or high Ki67-LI, straightforward clinical decisions could be offered, but for patients with intermediate Ki67-LI, other factors might provide valuable information.

The relationship between the occurrence of intractable epilepsy with glial cells and myelin sheath - an experimental study

OBJECTIVE

The occurrence of epilepsy is associated with myelin sheath injury; oligodendrocyte (OL) is the main cell of myelin sheath; In this study, we observed the changes of OL, demyelination, and myelin associated protein in different stages of intractable epilepsy (IE) at the epileptic foci of patients, and provide useful information for the pathophysiology of IE.

PATIENTS AND METHODS

IE patients who received epileptogenic focus resection were recruited as the experimental group, their medical records were collected and postoperative follow-up was performed. The brain tissues from10 cases with non-brain disorders were obtained as controls. Immunofluorescence double staining was used to observe OL expression. The demyelination in epileptic foci was observed by luxol fast blue (LFB) staining method. Real-time fluorescent quantitative (RT) PCR, Western blot methods were used to detect the expressions of myelin-related proteins.

RESULTS

We observed increased OL precursor cells, former OL and decreased mature OL in experimental group when compared with controls (both p < 0.05). The demyelination was obviously higher in experimental group when compared with controls (p < 0.01). We also observed significantly decreasing of myelin basic protein (MBP), oligodendrocytes myelin glycoprotein (OMgp), myelin associated glycoprotein (MAG) and other MAG associated proteins-Nogo receptors (NgRs) and GD1α (p < 0.01) in epileptic foci.

CONCLUSIONS

OL is differentiated abnormally at epileptic foci of patients with IE; the demyelination, decreasing of demyelination and myelin associated protein are related to the occurrence of IE.

Autophagy-linked FYVE containing protein WDFY3 interacts with TRAF6 and modulates RANKL-induced osteoclastogenesis

Recently, autophagy-related proteins were shown to regulate osteoclast mediated bone resorption, a critical process in autoimmune diseases such as rheumatoid arthritis. However, the role of autophagy-linked FYVE containing protein, WDFY3, in osteoclast biology remains elusive. WDFY3 is a master regulator in selective autophagy for clearing ubiquitinated protein aggregates and has been linked with rheumatoid arthritis. Herein, we used a series of WDFY3 transgenic mice (Wdfy3(lacZ) and Wdfy3(loxP)) to investigate the function of WDFY3 in osteoclast development and function. Our data demonstrate that WDFY3 is highly expressed at the growth plate of neonatal mice and is expressed in osteoclasts in vitro cultures. Osteoclasts derived from WDFY3 conditional knockout mice (Wdfy3(loxP/loxP)-LysM-Cre(+)) demonstrated increased osteoclast differentiation as evidenced by higher number and enlarged size of TRAP(+) multinucleated cells. Western blot analysis also revealed up-regulation of TRAF6 and an increase in RANKL-induced NF-κB signaling in WDFY3-deficient bone marrow-derived macrophages compared to wild type cultures. Consistent with these observations WDFY3-deficient cells also demonstrated an increase in osteoclast-related genes Ctsk, Acp5, Mmp9 and an increase of dentine resorption in in vitro assays. Importantly, in vivo RANKL gene transfer exacerbated bone loss in WDFY3 conditional knockout mice, as evidenced by elevated serum TRAP, CTX-I and micro-CT analysis of distal femurs compared to wild type littermates. Taken together, our data highlight a novel role for WDFY3 in osteoclast development and function, which can be exploited for the treatment of musculoskeletal diseases.

Macrophage migration inhibitory factor is essential for osteoclastogenic mechanisms in vitro and in vivo mouse model of arthritis

Macrophage migration inhibitory factor (MIF) enhances activation of leukocytes, endothelial cells and fibroblast-like synoviocytes (FLS), thereby contributing to the pathogenesis of rheumatoid arthritis (RA). A MIF promoter polymorphism in RA patients resulted in higher serum MIF concentration and worsens bone erosion; controversially current literature reported an inhibitory role of MIF in osteoclast formation. The controversial suggested that the precise role of MIF and its putative receptor CD74 in osteoclastogenesis and RA bone erosion, mediated by locally formed osteoclasts in response to receptor activator of NF-κB ligand (RANKL), is unclear. We reported that in an in vivo K/BxN serum transfer arthritis, reduced clinical and histological arthritis in MIF(-/-) and CD74(-/-) mice were accompanied by a virtual absence of osteoclasts at the synovium-bone interface and reduced osteoclast-related gene expression. Furthermore, in vitro osteoclast formation and osteoclast-related gene expression were significantly reduced in MIF(-/-) cells via decreasing RANKL-induced phosphorylation of NF-κB-p65 and ERK1/2. This was supported by a similar reduction of osteoclastogenesis observed in CD74(-/-) cells. Furthermore, a MIF blockade reduced RANKL-induced osteoclastogenesis via deregulating RANKL-mediated NF-κB and NFATc1 transcription factor activation. These data indicate that MIF and CD74 facilitate RANKL-induced osteoclastogenesis, and suggest that MIF contributes directly to bone erosion, as well as inflammation, in RA.