Profiles of central nervous system surgical site infections in endoscopic transnasal surgery exposing the intradural space

OBJECTIVE

Despite its efficacy and minimal invasiveness, the clean-contaminated nature of endoscopic transnasal surgery (ETS) may be susceptible to central nervous system surgical site infections (CNS-SSIs), especially when involving intradural exposure. However, the profiles of ETS-associated CNS-SSIs are not fully elucidated.

METHODS

The institutional ETS cases performed between May 2017 and March 2023 were retrospectively analysed. The incidences of CNS-SSIs were calculated, and their risk factors examined.

RESULTS

The incidence of CNS-SSIs was 2.3% (7/305) in the entire cohort and 5.0% (7/140) in ETSs with intradural exposure. All the CNS-SSIs were meningitis and developed following ETS with intradural exposure. The incidences were 0%, 5.6% and 5.8% in ETSs with Esposito grade 1, 2 and 3 intraoperative cerebrospinal fluid leakage, respectively. Among the pre- and intra-operative factors, body mass index (unit odds ratio (OR), 0.62; 95% confidence interval (CI), 0.44-0.89; P<0.01), serum albumin (unit OR, 0.03; 95% CI, 0.0007-0.92; P=0.02), and American Society of Anesthesiologists physical status score (unit OR, 20.7; 95% CI, 1.65-259; P<0.01) were significantly associated with CNS-SSIs. Moreover, postoperative cerebrospinal fluid leakage was also significantly associated with CNS-SSIs (OR, 18.4; 95% CI, 3.55-95.0; P<0.01).

CONCLUSIONS

The incidence of ETS-associated CNS-SSIs is acceptably low. Intradural exposure was a prerequisite for CNS-SSIs. Malnutrition and poor comorbidity status should be recognized as important risks for CNS-SSIs in ETS.

Novel mechanism of cisplatin resistance in head and neck squamous cell carcinoma involving extracellular vesicles and a copper transporter system

BACKGROUND

Cisplatin (CDDP) plays a central role in chemotherapy for head and neck squamous cell carcinoma (HNSCC), but drug resistance in HNSCC chemotherapy remains a problem, and the mechanism of CDDP resistance is unclear. We investigated CDDP-resistance mechanisms mediated by extracellular vesicles (EVs) and ATPase copper transporting beta (ATP7B) in HNSCC.

METHODS

We established CDDP-resistant sublines of HNSCC cells and verified their ATP7B expression. We used an EV secretion inhibitor (GW4869) and ATP7B short hairpin (sh)RNA transfection to examine the correlation between EV secretion and ATP7B expression.

RESULTS

The CDDP-resistant HNSCC sublines showed decreased CDDP sensitivity and increased ATP7B expression. GW4869 suppressed ATP7B expression, and ATP7B shRNA transfection suppressed EV secretion. The suppressions of EV secretion and ATP7B expression both enhanced CDDP's cell-killing effect.

CONCLUSIONS

EVs were involved in the ATP7B-mediated mechanism underlying CDDP resistance. Further clarification of the EV-induced CDDP-resistance mechanism may lead to novel therapeutic strategies for HNSCC.

Rab11 suppresses head and neck carcinoma by regulating EGFR and EpCAM exosome secretion

OBJECTIVES

Rab11(Rab11a and Rab11b) localizes primarily along recycling endosomes in cells and is involved in various intracellular trafficking processes, including membrane receptor recycling and secretion of exosomes or small extracellular vesicles (EVs). Although Rab11 is closely associated with the progression and metastasis of various cancer types, little is known about Rab11' role in head and neck squamous cell carcinoma (HNSCC). In this study, we investigated the roles of Rab11a and Rab11b in HNSCC.

METHODS

The clinical significance of Rab11 expression in HNSCC was investigated using a public database and tissue microarray analysis. Stable cell lines with loss and gain of Rab11a or Rab11b were originally established to investigate their roles in the proliferative, migratory, and invasive capabilities of HNSCC cells.

RESULTS

Database analysis revealed a significant association between Rab11b mRNA expression and a favorable patient survival rate in HNSCC. Tissue microarray analysis revealed that Rab11b expression was the highest in normal tissues and gradually decreased across the stages of HNSCC progression. Overexpression of Rab11a or Rab11b resulted in a decrease in epidermal growth factor receptor (EGFR), Epithelial cell adhesion molecule (EpCAM) exosome secretion, and the migratory and invasive potential of HNSCC cells. The knockdown of Rab11a or Rab11b increased EpCAM/CD9 exosome secretion in addition to the migratory and invasive potential of HNSCC cells.

CONCLUSIONS

Rab11 suppresses HNSCC by regulating EGFR recycling and EpCAM exosome secretion in HNSCC cells. Our results indicate that Rab11b is a superior prognostic indicator of HNSCC and holds promise for developing novel therapeutic strategies.

Multidisciplinary management of locally recurrent rectal cancer with carbon ion radiotherapy followed by prophylactic removal of the irradiated bowel: a case report

BACKGROUND

Locally recurrent rectal cancer (LRRC) involving the upper sacrum is typically incurable, and palliative treatment is the only option for most patients, resulting in a poor prognosis and reduced quality of life. Carbon ion radiotherapy (CIRT) has emerged as a promising modality for treating LRRC. This report presents a case of LRRC with sacral involvement that was managed via multidisciplinary therapy incorporating CIRT.

CASE PRESENTATION

A 55-year-old male was diagnosed with an anastomotic recurrence of rectal cancer 15 months after undergoing anterior resection. Computed tomography (CT) suggested that the lesion was at an anastomosis site and broadly adherent to the upper sacrum, and colonoscopy confirmed the diagnosis of LRRC. Histopathological examination of the biopsy specimens revealed adenocarcinoma cells and that lesion was genetically RAS-wild. Induction chemotherapy with mFOLFOX6 and panitumumab was used as the first treatment. The recurrent lesion shrank and no signs of distant metastasis were observed after 11 cycles, although the range of the lesions attached to the sacrum remained unchanged. Therefore, we provided CIRT for this inoperable lesion and prophylactically removed the radiation-exposed bowel including the recurrent lesion, because radiation-induced ulcers can cause bleeding and perforation. Despite the presence of considerable fibrosis in the irradiated region, the operation was successful and the postoperative course had no untoward incidents. He is still recurrence-free 24 months following surgery, despite the lack of adjuvant chemotherapy. This is the first report of CIRT followed by CIRT-irradiated bowel removal for an unresectable anastomosis recurrent lesion.

CONCLUSIONS

The clinical course of this case suggests that CIRT could be a potentially effective therapeutic option for LRRC involving the bowel, as long as the prophylactic removal of the irradiated bowel is performed at the optimal time. Further research involving larger sample sizes is warranted to validate the findings and conclusions of this case report.

Erratum: Search for Cosmic-Ray Boosted Sub-GeV Dark Matter Using Recoil Protons at Super-Kamiokande [Phys. Rev. Lett. 130, 031802 (2023)]

This corrects the article DOI: 10.1103/PhysRevLett.130.031802.

Abr, a Rho-regulating protein, modulates osteoclastogenesis by enhancing lamellipodia formation by interacting with poly(ADP-ribose) glycohydrolase

BACKGROUND

Osteoclasts are multinucleated bone-resorbing cells formed by the fusion of monocyte/macrophage lineage. During osteoclast differentiation, Rho GTPases are involved in various processes, including cell migration, adhesion, and polarity. However, the role of Rho-regulatory molecules in the regulation of osteoclast differentiation remains unclear. In this study, among these genes, we focused on active breakpoint cluster region-related (Abr) protein that is a multifunctional regulator of Rho GTPases.

METHODS AND RESULTS

We examined using knockdown and overexpression experiments in RANKL-stimulated RAW-D macrophages whether Abr regulates osteoclast differentiation and cell morphology. We observed an increase in Abr expression during osteoclast differentiation and identified expression of a variant of the Abr gene in osteoclasts. Knockdown of Abr suppressed osteoclast differentiation and resorption. Abr knockdown markedly inhibited the expression of osteoclast markers, such as Nfatc1, c-fos, Src, and Ctsk in osteoclasts. Conversely, overexpression of Abr enhanced the formation of multinucleated osteoclasts, bone resorption activity, and osteoclast marker gene expression. Moreover, Abr overexpression accelerated lamellipodia formation and induced the formation of well-developed actin in osteoclasts. Importantly, the Abr protein interacted with poly(ADP-ribose) glycohydrolase (PARG) and Rho GTPases, including RhoA, Rac1/2/3, and Cdc42 in osteoclasts.

CONCLUSIONS

Taken together, these results indicate that Abr modulates osteoclastogenesis by enhancing lamellipodia formation via its interaction with PARG.

Effect of Blonanserin on the Proliferation and Migration of Glioblastoma Cells

Glioblastoma is a highly malignant and invasive brain tumor, and there is an urgent need to establish a treatment option that prevents its growth and metastasis. Blonanserin is an antipsychotic drug widely used in the treatment of schizophrenia. It has recently been reported to inhibit the growth of breast cancer cells. In this study, we investigated the effect of blonanserin on the proliferation and migration of glioblastoma cells. The anti-proliferative activity of blonanserin was evaluated in terms of cell viability, competition, and cell death pathways in glioblastoma. Cell viability studies showed that blonanserin had growth inhibitory ability regardless of the malignancy of glioblastoma cells, but at concentrations close to its IC₅₀, it only had a slight cell death-inducing effect. Blonanserin showed growth inhibitory activity without D₂ antagonism following an independent competition analysis using blonanserin and D₂ antagonists. When the anti-migration activity of U251 cells was measured, blonanserin was found to attenuate cell migration. Furthermore, treatment with blonanserin at concentrations close to its IC₅₀ value inhibited extensive filament actin formation. In conclusion, blonanserin inhibited the proliferation and migration of glioblastoma cells independent of D₂ antagonism. The present study shows that blonanserin may serve as a seed compound for the discovery of new glioblastoma therapeutics to prevent the growth and metastasis of glioblastoma.

Search for Cosmic-Ray Boosted Sub-GeV Dark Matter Using Recoil Protons at Super-Kamiokande

We report a search for cosmic-ray boosted dark matter with protons using the 0.37  megaton×years data collected at Super-Kamiokande experiment during the 1996-2018 period (SKI-IV phase). We searched for an excess of proton recoils above the atmospheric neutrino background from the vicinity of the Galactic Center. No such excess is observed, and limits are calculated for two reference models of dark matter with either a constant interaction cross section or through a scalar mediator. This is the first experimental search for boosted dark matter with hadrons using directional information. The results present the most stringent limits on cosmic-ray boosted dark matter and exclude the dark matter-nucleon elastic scattering cross section between 10^{-33}cm^{2} and 10^{-27}cm^{2} for dark matter mass from 1  MeV/c^{2} to 300  MeV/c^{2}.

HSP90 drives the Rab11a-mediated vesicular transport of the cell surface receptors in osteoclasts

Rab11a, which ubiquitously localizes to early and recycling endosomes, is required for regulating the vesicular transport of cellular cargos. Interestingly, our previous study revealed that Rab11a served as a negative regulator of osteoclastogenesis by facilitating the lysosomal proteolysis of (1) colony-stimulating factor-1 (c-fms) receptor and (2) receptor activator of nuclear factor-κB (RANK) receptor, thereby resulting in inhibition of osteoclast (OC) differentiation, maturation, and bone-resorbing activity. However, the molecular mechanisms of how Rab11a negatively affected osteoclastogenesis were largely unknown. Heat shock protein (HSP90), including two isoforms HSP90α and HSP90β, necessitates the stability, maturation, and activity of a broad range of its clients, and is essentially required for a vast array of signal transduction pathways in nonstressful conditions. Furthermore, cumulative evidence suggests that HSP90 is a vital element of the vesicular transport network. Indeed, our recent study revealed that HSP90, a novel effector protein of Rab11b, modulated Rab11b-mediated osteoclastogenesis. In this study, we also found that Rab11a interacted with both HSP90α and HSP90β in OCs. Upon blockade of HSP90 ATPase activity by a specific inhibitor(17-allylamino-demethoxygeldanamycin), we showed that (1) the ATPase domain of HSP90 was a prerequisite for the interaction between HSP90 and Rab11a, and (2) the interaction of HSP90 to Rab11a sufficiently maintained the inhibitory effects of Rab11a on osteoclastogenesis. Altogether, our findings undoubtedly indicate a novel role of HSP90 in regulating Rab11a-mediated osteoclastogenesis.

SWI by 7T MR Imaging for the Microscopic Imaging Diagnosis of Astrocytic and Oligodendroglial Tumors

BACKGROUND AND PURPOSE

Despite advances in molecular imaging, preoperative diagnosis of astrocytomas and oligodendrogliomas can be challenging. In the present study, we assessed whether 7T SWI can be used to distinguish astrocytomas and oligodendrogliomas and whether malignant grading of gliomas is possible.

MATERIALS AND METHODS

7T SWI was performed on 21 patients with gliomas before surgery with optimization for sharp visualization of the corticomedullary junction. Scoring for cortical thickening and displacement of medullary vessels, characteristic of oligodendroglial tumors, and cortical tapering, characteristic of astrocytic tumors, was performed. Additionally, characteristics of malignancy, including thickening of the medullary veins, the presence of microbleeds, and/or necrosis were scored.

RESULTS

Scoring for oligodendroglial (highest possible score, +3) and astrocytic (lowest score possible, -3) characteristics yielded a significant difference between astrocytomas and oligodendrogliomas (mean, -1.93 versus +1.71, P < .01). Scoring for malignancy was significantly different among the World Health Organization grade II (n = 10), grade III (n = 4), and grade IV (n = 7) tumors (mean, 0.20 versus 1.38 versus 2.79). Cortical thickening was observed significantly more frequently in oligodendrogliomas (P < .02), with a sensitivity of 71.4% and specificity of 85.7%; observation of tapering of the cortex was higher in astrocytomas (P < .01) with a sensitivity of 85.7% and specificity of 100%.

CONCLUSIONS

Visualization of the corticomedullary junction by 7T SWI was useful in distinguishing astrocytomas and oligodendrogliomas. Observation of tapering of the cortex was most sensitive and specific for diagnosing astrocytomas. Reliably predicting malignant grade was also possible by 7T SWI.

Coronin1C Is a GDP-Specific Rab44 Effector That Controls Osteoclast Formation by Regulating Cell Motility in Macrophages

Osteoclasts are multinucleated bone-resorbing cells that are formed by the fusion of macrophages. Recently, we identified Rab44, a large Rab GTPase, as an upregulated gene during osteoclast differentiation that negatively regulates osteoclast differentiation. However, the molecular mechanisms by which Rab44 negatively regulates osteoclast differentiation remain unknown. Here, we found that the GDP form of Rab44 interacted with the actin-binding protein, Coronin1C, in murine macrophages. Immunoprecipitation experiments revealed that the interaction of Rab44 and Coronin1C occurred in wild-type and a dominant-negative (DN) mutant of Rab44, but not in a constitutively active (CA) mutant of Rab44. Consistent with these findings, the expression of the CA mutant inhibited osteoclast differentiation, whereas that of the DN mutant enhanced this differentiation. Using a phase-contrast microscope, Coronin1C-knockdown osteoclasts apparently impaired multinuclear formation. Moreover, Coronin1C knockdown impaired the migration and chemotaxis of RAW-D macrophages. An in vivo experimental system demonstrated that Coronin1C knockdown suppresses osteoclastogenesis. Therefore, the decreased cell formation and fusion of Coronin1C-depleted osteoclasts might be due to the decreased migration of Coronin1C-knockdown macrophages. These results indicate that Coronin1C is a GDP-specific Rab44 effector that controls osteoclast formation by regulating cell motility in macrophages.

Rab34 plays a critical role as a bidirectional regulator of osteoclastogenesis

Accumulating evidence suggests that Rab GTPases representing the largest branch of Ras superfamily have recently emerged as the core factors for the regulation of osteoclastogenesis through modulating vesicular transport amongst specific subcellular compartments. Among these, Rab34 GTPase has been identified to be important for the post-Golgi secretory pathway and for phagocytosis; nevertheless, its specific role in osteoclastogenesis has been completely obscure. Here, upon the in vitro model of osteoclast formation derived from murine macrophages like RAW-D cells or bone marrow-derived macrophages, we reveal that Rab34 regulates osteoclastogenesis bidirectionally. More specifically, Rab34 serves as a negative regulator of osteoclast differentiation by promoting the lysosome-induced proteolysis of two osteoclastogenic surface receptors, c-fms and RANK, via the axis of early endosomes-late endosomes-lysosomes, leading to alleviate the transcriptional activity of two of the master regulator of osteoclast differentiation, c-fos and NFATc-1, eventually attenuating osteoclast differentiation and bone resorption. Besides, Rab34 plays a crucial role in modulating the secretory network of lysosome-related proteases including matrix metalloprotease 9 and Cathepsin K across the ruffled borders of osteoclasts, contributing to the regulation of bone resorption.

Resident stroma-secreted chemokine CCL2 governs myeloid-derived suppressor cells in the tumor microenvironment

Accumulating evidence has shown that cancer stroma and BM-derived cells (BMDCs) in the tumor microenvironment (TME) play vital roles in tumor progression. However, the mechanism by which oral cancer stroma recruits any particular subset of BMDCs remains largely unknown. Here, we sought to identify the subset of BMDCs that is recruited by cancer stroma. We established a sequential transplantation model in BALB/c nude mice, including (a) BM transplantation of GFP-expressing cells and (b) coxenografting of patient-derived stroma (PDS; 2 cases, designated PDS1 and PDS2) with oral cancer cells (HSC-2). As controls, xenografting was performed with HSC-2 alone or in combination with normal human dermal fibroblasts (HDF). PDS1, PDS2, and HDF all promoted BMDC migration in vitro and recruitment in vivo. Multicolor immunofluorescence revealed that the PDS coxenografts recruited Arginase-1⁺CD11b⁺GR1⁺GFP⁺ cells, which are myeloid-derived suppressor cells (MDSCs), to the TME, whereas the HDF coxenograft did not. Screening using microarrays revealed that PDS1 and PDS2 expressed CCL2 mRNA (encoding C-C motif chemokine ligand 2) at higher levels than did HDF. Indeed, PDS xenografts contained significantly higher proportions of CCL2⁺ stromal cells and CCR2⁺Arginase-1⁺CD11b⁺GR1⁺ MDSCs (as receiver cells) than the HDF coxenograft. Consistently, a CCL2 synthesis inhibitor and a CCR2 antagonist significantly inhibited the PDS-driven migration of BM cells in vitro. Furthermore, i.p. injection of the CCR2 antagonist to the PDS xenograft models significantly reduced the CCR2⁺Arginase-1⁺CD11b⁺GR1⁺ MDSC infiltration to the TME. In conclusion, oral cancer stroma–secreted CCL2 is a key signal for recruiting CCR2⁺ MDSCs from BM to the TME.

A novel role of HSP90 in regulating osteoclastogenesis by abrogating Rab11b-driven transport

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that plays a pivotal role in folding, activating and assembling a variety of client proteins. In addition, HSP90 has recently emerged as a crucial regulator of vesicular transport of cellular proteins. In our previous study, we revealed Rab11b negatively regulated osteoclastogenesis by promoting the lysosomal proteolysis of c-fms and RANK surface receptors via the axis of early endosome-late endosome-lysosomes. In this study, using an in vitro model of osteoclasts differentiated from murine macrophage-like RAW-D cells, we revealed that Rab11b interacted with both HSP90 isoforms, HSP90 alpha (HSP90α) and HSP90 beta (HSP90β), suggesting that Rab11b is an HSP90 client. Using at specific blocker for HSP90 ATPase activity, 17-allylamino-demethoxygeldanamycin (17-AAG), we found that the HSP90 ATPase domain is indispensable for maintaining the interaction between HSP90 and Rab11b in osteoclasts. Nonetheless, its ATPase activity is not required for regulating the turnover of endogenous Rab11b. Interestingly, blocking the interaction between HSP90 and Rab11b by either HSP90-targeting small interfering RNA (siHSP90) or 17-AAG abrogated the inhibitory effects of Rab11b on osteoclastogenesis by suppressing the Rab11b-mediated transport of c-fms and RANK surface receptors to lysosomes via the axis of early endosome-late endosome-lysosomes, alleviating the Rab11b-mediated proteolysis of these surface receptors in osteoclasts. Based on our observations, we propose a HSP90/Rab11b-mediated regulatory mechanism for osteoclastogenesis by directly modulating the c-fms and RANK surface receptors in osteoclasts, thereby contributing to the maintenance of bone homeostasis.

Exosome-Based Molecular Transfer Activity of Macrophage-Like Cells Involves Viability of Oral Carcinoma Cells: Size Exclusion Chromatography and Concentration Filter Method

Extracellular vesicles (EV) heterogeneity is a crucial issue in biology and medicine. In addition, tumor-associated macrophages are key components in cancer microenvironment and immunology. We developed a combination method of size exclusion chromatography and concentration filters (SEC-CF) and aimed to characterize different EV types by their size, cargo types, and functions. A human monocytic leukemia cell line THP-1 was differentiated to CD14-positive macrophage-like cells by stimulation with PMA (phorbol 12-myristate 13-acetate) but not M1 or M2 types. Using the SEC-CF method, the following five EV types were fractionated from the culture supernatant of macrophage-like cells: (i) rare large EVs (500–3000 nm) reminiscent of apoptosomes, (ii) EVs (100–500 nm) reminiscent of microvesicles (or microparticles), (iii) EVs (80–300 nm) containing CD9-positive large exosomes (EXO-L), (iv) EVs (20–200 nm) containing unidentified vesicles/particles, and (v) EVs (10–70 nm) containing CD63/HSP90-positive small exosomes (EXO-S) and particles. For a molecular transfer assay, we developed a THP-1-based stable cell line producing a GFP-fused palmitoylation signal (palmGFP) associated with the membrane. The THP1/palmGFP cells were differentiated into macrophages producing palmGFP-contained EVs. The macrophage/palmGFP-secreted EXO-S and EXO-L efficiently transferred the palmGFP to receiver human oral carcinoma cells (HSC-3/palmTomato), as compared to other EV types. In addition, the macrophage-secreted EXO-S and EXO-L significantly reduced the cell viability (ATP content) in oral carcinoma cells. Taken together, the SEC-CF method is useful for the purification of large and small exosomes with higher molecular transfer activities, enabling efficient molecular delivery to target cells.

Rab44 isoforms similarly promote lysosomal exocytosis, but exhibit differential localization in mast cells

Rab44 is a large Rab GTPase containing a Rab GTPase domain and some additional N-terminal domains. We recently used Rab44-deficient mice to demonstrate that Rab44 regulates granule exocytosis in mast cells and IgE-mediated anaphylaxis. In mouse mast cells, Rab44 is expressed as two isoforms, namely, the long and short forms; however, the characteristics of these two isoforms remain unknown. Here, we investigated secretion and localization of the human long Rab44 isoform and the two mouse isoforms and their mutants expressed in rat basophilic leukemia (RBL)-2H3 cells. Expression of the human long isoform and both mouse isoforms caused an increase in β-hexosaminidase secretion. Confocal and quantitative analyses showed that both human and mouse long isoforms localized mainly to lysosomes while the mouse short isoform localized mainly to the ER. Live imaging with LysoTracker indicated that the size and number of LysoTracker-positive vesicles were altered by the various mutants. Ionomycin treatment partially altered localization of both long isoforms to the plasma membrane and cytosol, whereas it had little effect on colocalization of the short isoform with lysosomes. Mechanistically, both human and mouse Rab44 proteins interacted with vesicle-associated membrane protein 8 (VAMP8), a v-SNARE protein. Therefore, Rab44 isoforms similarly promote lysosomal exocytosis, but exhibit differential localization in mast cells.

Inhibition of growth and virulence of Vibrio cholerae by carvacrol, an essential oil component of Origanum spp

AIMS

In the age where bacterial resistance to conventional antibiotics is increasing at an alarming rate, the use of the traditional plant, herb extracts or other bioactive constituents is gradually becoming popular as an anti-virulence agent to treat pathogenic diseases. Carvacrol, a major essential oil fraction of Oregano, possesses a wide range of bioactivities. Therefore, we aimed to study the effect of sub-inhibitory concentrations of carvacrol on major virulence traits of Vibrio cholerae.

METHODS AND RESULTS

We have used in vitro as well as ex vivo models to access the anti-pathogenic role of carvacrol. We found that the sub-inhibitory concentration of carvacrol significantly repressed bacterial mucin penetrating ability. Carvacrol also reduced the adherence and fluid accumulation in the rabbit ileal loop model. Reduction in virulence is associated with the downregulated expression of tcpA, ctxB, hlyA and toxT. Furthermore, carvacrol inhibits flagellar synthesis by downregulating the expression of flrC and most of the class III genes.

CONCLUSIONS

Carvacrol exhibited anti-virulence activity against V. cholerae, which involved many events including the inhibition of mucin penetration, adhesion, reduced expression of virulence-associated genes culminating in reduced fluid accumulation.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings indicate that carvacrol possesses inhibitory activity against V. cholerae pathogenesis and might be considered as a potential bio-active therapeutic alternative to combat cholera.

The Inhibitory Role of Rab11b in Osteoclastogenesis through Triggering Lysosome-Induced Degradation of c-Fms and RANK Surface Receptors

Rab11b, abundantly enriched in endocytic recycling compartments, is required for the establishment of the machinery of vesicle trafficking. Yet, no report has so far characterized the biological function of Rab11b in osteoclastogenesis. Using in vitro model of osteoclasts differentiated from murine macrophages like RAW-D cells or bone marrow-derived macrophages, we elucidated that Rab11b served as an inhibitory regulator of osteoclast differentiation sequentially via (i) abolishing surface abundance of RANK and c-Fms receptors; and (ii) attenuating nuclear factor of activated T-cells c1 (NFATc-1) upstream signaling cascades, following RANKL stimulation. Rab11b was localized in early and late endosomes, Golgi complex, and endoplasmic reticulum; moreover, its overexpression enlarged early and late endosomes. Upon inhibition of lysosomal function by a specific blocker, chloroquine (CLQ), we comprehensively clarified a novel function of lysosomes on mediating proteolytic degradation of c-Fms and RANK surface receptors, drastically ameliorated by Rab11b overexpression in RAW-D cell-derived osteoclasts. These findings highlight the key role of Rab11b as an inhibitor of osteoclastogenesis by directing the transport of c-Fms and RANK surface receptors to lysosomes for degradation via the axis of early endosomes-late endosomes-lysosomes, thereby contributing towards the systemic equilibrium of the bone resorption phase.

(-)-Epigallocatechin-3-gallate inhibits RANKL-induced osteoclastogenesis via downregulation of NFATc1 and suppression of HO-1-HMGB1-RAGE pathway

Osteoporosis disturbs the balance of bone metabolism, and excessive bone resorption causes a decrease in bone density, thus increasing the risk of fracture. (-)-Epigallocatechin-3-gallate (EGCG) is the most abundant catechin contained in green tea. EGCG has a variety of pharmacological activities. Recently, it was reported that EGCG inhibits osteoclast differentiation, but the details of the mechanism underlying the EGCG-mediated suppression of osteoclastogenesis are unknown. In this study, we investigated the effects of EGCG on several signaling pathways in osteoclastogenesis. EGCG suppressed the expression of the nuclear factor of activated T cells cytoplasmic-1 (NFATc1), the master regulator of osteoclastogenesis. EGCG decreased the expression of cathepsin K, c-Src, and ATP6V0d2 and suppressed bone resorption. We also found that EGCG upregulated heme oxygenase-1 (HO-1) and suppressed the extracellular release of high-mobility group box 1 (HMGB1). In addition, EGCG decreased the expression of the receptor for advanced glycation end products (RAGE), which is the receptor of HMGB1, in osteoclastogenesis. In summary, our study showed that EGCG could inhibit osteoclast differentiation through the downregulation of NFATc1 and the suppression of the HO-1-HMGB1-RAGE pathway. EGCG might have the potential to be a lead compound that suppresses bone resorption in the treatment of osteoporosis.

Pilot Study of Hyperpolarized 13C Metabolic Imaging in Pediatric Patients with Diffuse Intrinsic Pontine Glioma and Other CNS Cancers

BACKGROUND AND PURPOSE

Pediatric CNS tumors commonly present challenges for radiographic interpretation on conventional MR imaging. This study sought to investigate the safety and tolerability of hyperpolarized carbon-13 (HP-¹³C) metabolic imaging in pediatric patients with brain tumors.

MATERIALS AND METHODS

Pediatric patients 3 to 18 years of age who were previously diagnosed with a brain tumor and could undergo MR imaging without sedation were eligible to enroll in this safety study of HP [1-¹³C]pyruvate. Participants received a one-time injection of HP [1-¹³C]pyruvate and were imaged using dynamic HP-¹³C MR imaging. We assessed 2 dose levels: 0.34 mL/kg and the highest tolerated adult dose of 0.43 mL/kg. Participants were monitored throughout imaging and for 60 minutes postinjection, including pre- and postinjection electrocardiograms and vital sign measurements.

RESULTS

Between February 2017 and July 2019, ten participants (9 males; median age, 14 years; range, 10-17 years) were enrolled, of whom 6 completed injection of HP [1-¹³C]pyruvate and dynamic HP-¹³C MR imaging. Four participants failed to undergo HP-¹³C MR imaging due to technical failures related to generating HP [1-¹³C]pyruvate or MR imaging operability. HP [1-¹³C]pyruvate was well-tolerated in all participants who completed the study, with no dose-limiting toxicities or adverse events observed at either 0.34 (n = 3) or 0.43 (n = 3) mL/kg. HP [1-¹³C]pyruvate demonstrated characteristic conversion to [1-¹³C]lactate and [¹³C]bicarbonate in the brain. Due to poor accrual, the study was closed after only 3 participants were enrolled at the highest dose level.

CONCLUSIONS

Dynamic HP-¹³C MR imaging was safely performed in 6 pediatric patients with CNS tumors and demonstrated HP [1-¹³C]pyruvate brain metabolism.

Rab11A Functions as a Negative Regulator of Osteoclastogenesis through Dictating Lysosome-Induced Proteolysis of c-fms and RANK Surface Receptors

Osteoclast differentiation and activity are controlled by two essential cytokines, macrophage colony-stimulating factor (M-CSF) and the receptor activator of nuclear factor-κB ligand (RANKL). Rab11A GTPase, belonging to Rab11 subfamily representing the largest branch of Ras superfamily of small GTPases, has been identified as one of the crucial regulators of cell surface receptor recycling. Nevertheless, the regulatory role of Rab11A in osteoclast differentiation has been completely unknown. In this study, we found that Rab11A was strongly upregulated at a late stage of osteoclast differentiation derived from bone marrow-derived macrophages (BMMs) or RAW-D murine osteoclast precursor cells. Rab11A silencing promoted osteoclast formation and significantly increased the surface levels of c-fms and receptor activator of nuclear factor-κB (RANK) while its overexpression attenuated osteoclast formation and the surface levels of c-fms and RANK. Using immunocytochemical staining for tracking Rab11A vesicular localization, we observed that Rab11A was localized in early and late endosomes, but not lysosomes. Intriguingly, Rab11A overexpression caused the enhancement of fluorescent intensity and size-based enlargement of early endosomes. Besides, Rab11A overexpression promoted lysosomal activity via elevating the endogenous levels of a specific lysosomal protein, LAMP1, and two key lysosomal enzymes, cathepsins B and D in osteoclasts. More importantly, inhibition of the lysosomal activity by chloroquine, we found that the endogenous levels of c-fms and RANK proteins were enhanced in osteoclasts. From these observations, we suggest a novel function of Rab11A as a negative regulator of osteoclastogenesis mainly through (i) abolishing the surface abundance of c-fms and RANK receptors, and (ii) upregulating lysosomal activity, subsequently augmenting the degradation of c-fms and RANK receptors, probably via the axis of early endosomes-late endosomes-lysosomes in osteoclasts.

Relativistic magnetic reconnection in laser laboratory for testing an emission mechanism of hard-state black hole system

Magnetic reconnection in a relativistic electron magnetization regime was observed in a laboratory plasma produced by a high-intensity, large energy, picoseconds laser pulse. Magnetic reconnection conditions realized with a laser-driven several kilotesla magnetic field is comparable to that in the accretion disk corona of black hole systems, i.e., Cygnus X-1. We observed particle energy distributions of reconnection outflow jets, which possess a power-law component in a high-energy range. The hardness of the observed spectra could explain the hard-state x-ray emission from accreting black hole systems.

Prognostic and predictive values of tumour budding in stage IV colorectal cancer

BACKGROUND

Tumour budding is an important prognostic feature in early-stage colorectal cancer, but its prognostic significance in metastatic disease has not been fully investigated.

METHODS

Patients with stage IV disease who had primary colorectal tumour resection without previous chemotherapy or radiotherapy from January 2000 to December 2018 were reviewed retrospectively. Budding was evaluated at the primary site and graded according to the criteria of the International Tumor Budding Consensus Conference (ITBCC) (BD1, low; BD2, intermediate; BD3, high). Patients were categorized by metastatic (M1a, M1b) and resectional (R0/R1, R2/unresected) status. Subgroups were compared for overall (OS) and recurrence-free (RFS) survival in R0/R1 subgroups; R2/unresected patients were evaluated for the rate of tumour progression, based on change in tumour size from baseline.

RESULTS

Of 371 patients observed during the study, 362 were analysed. Patients with BD3 had a lower 5-year OS rate than those with BD1 + BD2 (18·4 versus 40·5 per cent; P < 0·001). Survival analyses according to metastatic and resection status also showed that BD3 was associated with shorter OS than BD1 + BD2. In multivariable analysis, BD3 (hazard ratio (HR) 1·51, 95 per cent c.i. 1·11 to 2·10; P = 0·009), T4 status (HR 1·39) and R2/unresected status (HR 3·50) were associated with decreased OS. In the R0/R1 subgroup, the 2-year RFS rate was similar for BD3 and BD1 + BD2 according to metastatic status. There was no significant difference between BD3 and BD1 + BD2 for change in tumour size in the R2/unresected subgroup (P = 0·094). Of 141 patients with initially unresectable metastases who had chemotherapy, 35 achieved conversion from unresectable to resectable status. The conversion rate was significantly higher for BD1 + BD2 than for BD3 (36 versus 18 per cent; P = 0·016).

CONCLUSION

Stage IV colorectal cancer with high-grade tumour budding according to ITBCC criteria correlates with poor prognosis.

Triple knockdown of CDC37, HSP90-alpha and HSP90-beta diminishes extracellular vesicles-driven malignancy events and macrophage M2 polarization in oral cancer

Evidence has been accumulating to indicate that extracellular vesicles (EVs), including exosomes, released by cancer cells can foster tumour progression. The molecular chaperones – CDC37, HSP90α and HSP90β play key roles in cancer progression including epithelial-mesenchymal transition (EMT), although their contribution to EVs-mediated cell–cell communication in tumour microenvironment has not been thoroughly examined. Here we show that triple depletion of the chaperone trio attenuates numerous cancer malignancy events exerted through EV release. Metastatic oral cancer-derived EVs (MEV) were enriched with HSP90α HSP90β and cancer-initiating cell marker CD326/EpCAM. Depletion of these chaperones individually induced compensatory increases in the other chaperones, whereas triple siRNA targeting of these molecules markedly diminished the levels of the chaperone trio and attenuated EMT. MEV were potent agents in initiating EMT in normal epithelial cells, a process that was attenuated by the triple chaperone depletion. The migration, invasion, and in vitro tumour initiation of oral cancer cells were significantly promoted by MEV, while triple depletion of CDC37/HSP90α/β reversed these MEV-driven malignancy events. In metastatic oral cancer patient-derived tumours, HSP90β was significantly accumulated in infiltrating tumour-associated macrophages (TAM) as compared to lower grade oral cancer cases. HSP90-enriched MEV-induced TAM polarization to an M2 phenotype, a transition known to support cancer progression, whereas the triple chaperone depletion attenuated this effect. Mechanistically, the triple chaperone depletion in metastatic oral cancer cells effectively reduced MEV transmission into macrophages. Hence, siRNA-mediated knockdown of the chaperone trio (CDC37/HSP90α/HSP90β) could potentially be a novel therapeutic strategy to attenuate several EV-driven malignancy events in the tumour microenvironment.

Abbreviations

CDC37: cell division control 37; EMT: epithelial-mesenchymal transmission; EV: extracellular vesicles; HNSCC: head and neck squamous cell carcinoma; HSP90: heat shock protein 90; TAM: tumour-associated macrophage

Knockout of MMP3 Weakens Solid Tumor Organoids and Cancer Extracellular Vesicles

The tumor organoid (tumoroid) model in three-dimensional (3D) culture systems has been developed to reflect more closely the in vivo tumors than 2D-cultured tumor cells. Notably, extracellular vesicles (EVs) are efficiently collectible from the culture supernatant of gel-free tumoroids. Matrix metalloproteinase (MMP) 3 is a multi-functional factor playing crucial roles in tumor progression. However, roles of MMP3 within tumor growth and EVs have not unveiled. Here, we investigated the protumorigenic roles of MMP3 on integrities of tumoroids and EVs. We generated MMP3-knockout (KO) cells using the CRISPR/Cas9 system from rapidly metastatic LuM1 tumor cells. Moreover, we established fluorescent cell lines with palmitoylation signal-fused fluorescent proteins (tdTomato and enhanced GFP). Then we confirmed the exchange of EVs between cellular populations and tumoroids. LuM1-tumoroids released large EVs (200-1000 nm) and small EVs (50-200 nm) while the knockout of MMP3 resulted in the additional release of broken EVs from tumoroids. The loss of MMP3 led to a significant reduction in tumoroid size and the development of the necrotic area within tumoroids. MMP3 and CD9 (a category-1 EV marker tetraspanin protein) were significantly down-regulated in MMP3-KO cells and their EV fraction. Moreover, CD63, another member of the tetraspanin family, was significantly reduced only in the EVs fractions of the MMP3-KO cells compared to their counterpart. These weakened phenotypes of MMP3-KO were markedly rescued by the addition of MMP3-rich EVs or conditioned medium (CM) collected from LuM1-tumoroids, which caused a dramatic rise in the expression of MMP3, CD9, and Ki-67 (a marker of proliferating cells) in the MMP3-null/CD9-low tumoroids. Notably, MMP3 enriched in tumoroids-derived EVs and CM deeply penetrated recipient MMP3-KO tumoroids, resulting in a remarkable enlargement of solid tumoroids, while MMP3-null EVs did not. These data demonstrate that EVs can mediate molecular transfer of MMP3, resulting in increasing the proliferation and tumorigenesis, indicating crucial roles of MMP3 in tumor progression.

Extracellular Vesicles Enriched with Moonlighting Metalloproteinase Are Highly Transmissive, Pro-Tumorigenic, and Trans-Activates Cellular Communication Network Factor (CCN2/CTGF): CRISPR against Cancer

Matrix metalloproteinase 3 (MMP3) plays multiple roles in extracellular proteolysis as well as intracellular transcription, prompting a new definition of moonlighting metalloproteinase (MMP), according to a definition of protein moonlighting (or gene sharing), a phenomenon by which a protein can perform more than one function. Indeed, connective tissue growth factor (CTGF, aka cellular communication network factor 2 (CCN2)) is transcriptionally induced as well as cleaved by MMP3. Moreover, several members of the MMP family have been found within tumor-derived extracellular vesicles (EVs). We here investigated the roles of MMP3-rich EVs in tumor progression, molecular transmission, and gene regulation. EVs derived from a rapidly metastatic cancer cell line (LuM1) were enriched in MMP3 and a C-terminal half fragment of CCN2/CTGF. MMP3-rich, LuM1-derived EVs were disseminated to multiple organs through body fluid and were pro-tumorigenic in an allograft mouse model, which prompted us to define LuM1-EVs as oncosomes in the present study. Oncosome-derived MMP3 was transferred into recipient cell nuclei and thereby trans-activated the CCN2/CTGF promoter, and induced CCN2/CTGF production in vitro. TRENDIC and other cis-elements in the CCN2/CTGF promoter were essential for the oncosomal responsivity. The CRISPR/Cas9-mediated knockout of MMP3 showed significant anti-tumor effects such as the inhibition of migration and invasion of tumor cells, and a reduction in CCN2/CTGF promoter activity and fragmentations in vitro. A high expression level of MMP3 or CCN2/CTGF mRNA was prognostic and unfavorable in particular types of cancers including head and neck, lung, pancreatic, cervical, stomach, and urothelial cancers. These data newly demonstrate that oncogenic EVs-derived MMP is a transmissive trans-activator for the cellular communication network gene and promotes tumorigenesis at distant sites.

Cell Stress Induced Stressome Release Including Damaged Membrane Vesicles and Extracellular HSP90 by Prostate Cancer Cells

Tumor cells exhibit therapeutic stress resistance-associated secretory phenotype involving extracellular vesicles (EVs) such as oncosomes and heat shock proteins (HSPs). Such a secretory phenotype occurs in response to cell stress and cancer therapeutics. HSPs are stress-responsive molecular chaperones promoting proper protein folding, while also being released from cells with EVs as well as a soluble form known as alarmins. We have here investigated the secretory phenotype of castration-resistant prostate cancer (CRPC) cells using proteome analysis. We have also examined the roles of the key co-chaperone CDC37 in the release of EV proteins including CD9 and epithelial-to-mesenchymal transition (EMT), a key event in tumor progression. EVs derived from CRPC cells promoted EMT in normal prostate epithelial cells. Some HSP family members and their potential receptor CD91/LRP1 were enriched at high levels in CRPC cell-derived EVs among over 700 other protein types found by mass spectrometry. The small EVs (30-200 nm in size) were released even in a non-heated condition from the prostate cancer cells, whereas the EMT-coupled release of EVs (200-500 nm) and damaged membrane vesicles with associated HSP90α was increased after heat shock stress (HSS). GAPDH and lactate dehydrogenase, a marker of membrane leakage/damage, were also found in conditioned media upon HSS. During this stress response, the intracellular chaperone CDC37 was transcriptionally induced by heat shock factor 1 (HSF1), which activated the CDC37 core promoter, containing an interspecies conserved heat shock element. In contrast, knockdown of CDC37 decreased EMT-coupled release of CD9-containing vesicles. Triple siRNA targeting CDC37, HSP90α, and HSP90β was required for efficient reduction of this chaperone trio and to reduce tumorigenicity of the CRPC cells in vivo. Taken together, we define "stressome" as cellular stress-induced all secretion products, including EVs (200-500 nm), membrane-damaged vesicles and remnants, and extracellular HSP90 and GAPDH. Our data also indicated that CDC37 is crucial for the release of vesicular proteins and tumor progression in prostate cancer.

Outer membrane vesicles of Porphyromonas gingivalis attenuate insulin sensitivity by delivering gingipains to the liver

Outer membrane vesicles (OMVs) are nanosized particles derived from the outer membrane of gram-negative bacteria. Oral bacterium Porphyromonas gingivalis (Pg) is known to be a major pathogen of periodontitis that contributes to the progression of periodontal disease by releasing OMVs. The effect of Pg OMVs on systemic diseases is still unknown. To verify whether Pg OMVs affect the progress of diabetes mellitus, we analyzed the cargo proteins of vesicles and evaluated their effect on hepatic glucose metabolism. Here, we show that Pg OMVs were equipped with Pg-derived proteases gingipains and translocated to the liver in mice. In these mice, the hepatic glycogen synthesis in response to insulin was decreased, and thus high blood glucose levels were maintained. Pg OMVs also attenuated the insulin-induced Akt/glycogen synthase kinase-3 β (GSK-3β) signaling in a gingipain-dependent fashion in hepatic HepG2 cells. These results suggest that the delivery of gingipains mediated by Pg OMV elicits changes in glucose metabolisms in the liver and contributes to the progression of diabetes mellitus.

Tumor Angiogenic Inhibition Triggered Necrosis (TAITN) in Oral Cancer

CXCR4 is a chemokine receptor crucial in tumor progression, although the angiogenic role of CXCR4 in oral squamous cell carcinoma (OSCC) has not been investigated. Here we show that CXCR4 is crucial for tumor angiogenesis, thereby supporting tumor survival in OSCC. Immunohistochemistry on human clinical specimens revealed that CXCR4 and a tumor vasculature marker CD34 were co-distributed in tumor vessels in human OSCC specimens. To uncover the effects of CXCR4 inhibition, we treated the OSCC-xenografted mice with AMD3100, so-called plerixafor, an antagonist of CXCR4. Notably, we found a unique pathophysiological structure defined as tumor angiogenic inhibition triggered necrosis (TAITN), which was induced by the CXCR4 antagonism. Treatment with AMD3100 increased necrotic areas with the induction of hypoxia-inducible factor-1α in the xenografted tumors, suggesting that AMD3100-induced TAITN was involved in hypoxia and ischemia. Taken together, we demonstrated that CXCR4 plays a crucial role in tumor angiogenesis required for OSCC progression, whereas TAITN induced by CXCR4 antagonism could be an effective anti-angiogenic therapeutic strategy in OSCC treatment.

A Reporter System Evaluates Tumorigenesis, Metastasis, β-catenin/MMP Regulation, and Druggability

Cancer invasion, metastasis, and therapy resistance are the crucial phenomena in cancer malignancy. The high expression of matrix metalloproteinase 9 (MMP9) is a biomarker as well as a causal factor of cancer invasiveness and metastatic activity. However, a regulatory mechanism underlying MMP9 expression in cancer is not clarified yet. In addition, a new strategy for anticancer drug discovery is becoming an important clue. In the present study, we aimed (i) to develop a novel reporter system evaluating tumorigenesis, invasiveness, metastasis, and druggability with a combination of three-dimensional tumoroid model and Mmp9 promoter and (ii) to examine pharmacological actions of anticancer medications using this reporter system. High expression and genetic amplification of MMP9 were found in colon cancer cases. We found that proximal promoter sequences of MMP9 in murine and human contained conserved binding sites for transcription factors β-catenin/TCF/LEF, glucocorticoid receptor (GR), and nuclear factor kappa-B (NF-κB). The murine Mmp9 promoter (-569 to +19) was markedly activated in metastatic colon cancer cells and additionally activated by tumoroid formation and by β-catenin signaling stimulator lithium chloride. The Mmp9 promoter-driven fluorescent reporter cells enabled the monitoring of activities of MMP9/gelatinase, tumorigenesis, invasion, and metastasis in syngeneic transplantation experiments. We also demonstrated pharmacological actions as follows: dexamethasone and hydrocortisone, steroidal medications binding to GR, inhibited the Mmp9 promoter but did not inhibit tumorigenesis. On the contrary, antimetabolite 5-fluorouracil, a gold standard for colon cancer chemotherapy, inhibited tumoroid formation but did not inhibit Mmp9 promoter activity. Notably, antimalaria medication artesunate inhibited both tumorigenesis and the Mmp9 promoter in vitro, potentially through inhibition of β-catenin/TCF/LEF signaling. Thus, this novel reporter system enabled monitoring tumorigenesis, invasiveness, metastasis, key regulatory signalings such as β-catenin/MMP9 axis, and druggability. Impact Statement Cancer invasion and metastasis have been shown to be driven by matrix metalloproteinase 9 (MMP9), whose expression mechanism is not clarified yet. In addition, a new strategy for anticancer drug discovery is becoming important. We established a novel reporter system evaluating tumorigenesis, invasiveness, metastasis, and druggability with a combination of three-dimensional (3D) tumoroid model and Mmp9 promoter. Using this reporter system, we demonstrated pharmacological actions of anticancer medications such as antimetabolite 5-fluorouracil (5-FU) and antimalaria medication artesunate (ART), which inhibited both tumorigenesis and β-catenin/MMP regulatory signaling. Our study impacts the translational fields of oncology, drug discovery, and organoid model.

KBTBD11, a novel BTB-Kelch protein, is a negative regulator of osteoclastogenesis through controlling Cullin3-mediated ubiquitination of NFATc1

Kelch repeat and BTB domain-containing protein 11 (KBTBD11) is a member of the KBTBD subfamily of proteins that possess a BTB domain and Kelch repeats. Despite the presence of the Kbtbd11 gene in mammalian genomes, there are few reports about KBTBD11 at present. In this study, we identified the novel protein KBTBD11 as a negative regulator of osteoclast differentiation. We found that expression of KBTBD11 increased during osteoclastogenesis. Small-interfering-RNA-mediated knockdown of KBTBD11 enhanced osteoclast formation, and markedly increased the expression of several osteoclast marker genes compared with control cells. Conversely, KBTBD11 overexpression impaired osteoclast differentiation, and decreased the expression of osteoclast marker genes. Among six major signaling pathways regulating osteoclast differentiation, KBTBD11 predominantly influenced the nuclear factor of activated T cell cytoplasmic-1 (NFATc1) pathway. Mechanistically, KBTBD11 was found to interact with an E3 ubiquitin ligase, Cullin3. Further experiments involving immunoprecipitation and treatment with MG132, a proteasome inhibitor, showed that the KBTBD11–Cullin3 promotes ubiquitination and degradation of NFATc1 by the proteasome. Considering that NFATc1 is an essential factor for osteoclast differentiation, the KBTBD11 and Cullin3 probably regulate the levels of NFATc1 through the ubiquitin-proteasome degradation system. Thus, KBTBD11 negatively modulates osteoclast differentiation by controlling Cullin3-mediated ubiquitination of NFATc1.

Nicotine promotes lymph node metastasis and cetuximab resistance in head and neck squamous cell carcinoma

Epidermal growth factor (EGF) is overexpressed in many cancers and is associated with worse prognosis. EGF binds to its cell surface receptor (EGFR), which induces EGFR phosphorylation. Phosphorylated EGFR (p‑EGFR) is translocated into the nucleus, which increases cancer cell activity. Nicotine, which is one of the main components of tobacco, is absorbed through pulmonary alveoli and mucosal epithelia in the head and neck region by smoking and moves into the blood. Nicotine in blood binds to nicotinic acetylcholine receptor (nAChR) in the central nervous system and serves a crucial role in tobacco addiction. Although nAChR localization is thought to be limited in the nervous system, nAChR is present in a wide variety of non‑neuronal cells, including cancer cells. Recent studies suggest that nicotine contributes to the metastasis and resistance to anti‑cancer drugs of various cancer cells. However, it remains unknown whether head and neck squamous cell carcinoma (HNSCC) cells can utilize nicotine‑nAChR signaling to metastasize and acquire resistance to anti‑cancer drugs, even though the mucosal epithelia of the head and neck region are the primary sites of exposure to tobacco smoke. To the best of our knowledge, the present study is the first to demonstrate the role of nicotine in metastasis and anti‑EGFR‑therapy resistance of HNSCC. The present findings demonstrated that nicotine increased proliferation, migration, invasion, p‑EGFR nuclear translocation and protein kinase B (Akt) phosphorylation in HNSCC cells. It was also demonstrated that nicotine restored cetuximab‑inhibited proliferation, migration and invasion of HNSCC cells. Finally, an in vivo experiment revealed that nicotine increased lymph node metastasis of xenografted tumors, whereas an nAChR inhibitor suppressed lymph node metastasis and p‑EGFR nuclear localization of xenografted tumors. Taken together, these results demonstrated that nicotine induced nuclear accumulation of p‑EGFR, and activation of Akt signaling. These signaling pathways elevated the activities of HNSCC cells, causing lymph node metastasis and serving a role in cetuximab resistance.

Depletion of Lipid Efflux Pump ABCG1 Triggers the Intracellular Accumulation of Extracellular Vesicles and Reduces Aggregation and Tumorigenesis of Metastatic Cancer Cells

The ATP-binding cassette transporter G1 (ABCG1) is a cholesterol lipid efflux pump whose role in tumor growth has been largely unknown. Our transcriptomics revealed that ABCG1 was powerfully expressed in rapidly metastatic, aggregative colon cancer cells, in all the ABC transporter family members. Coincidently, genetic amplification of ABCG1 is found in 10–35% of clinical samples of metastatic cancer cases. Expression of ABCG1 was further elevated in three-dimensional tumoroids (tumor organoids) within stemness-enhancing tumor milieu, whereas depletion of ABCG1 lowered cellular aggregation and tumoroid growth in vitro as well as hypoxia-inducible factor 1α in cancer cells around the central necrotic areas in tumors in vivo. Notably, depletion of ABCG1 triggered the intracellular accumulation of extracellular vesicles (EVs) and regression of tumoroids. Collectively, these data suggest that ABCG1 plays a crucial role in tumorigenesis in metastatic cancer and that depletion of ABCG1 triggers tumor regression with the accumulation of EVs and their derivatives and cargos, implicating a novel ABCG1-targeting therapeutic strategy by which redundant and toxic substances may be accumulated in tumors leading to their regression.

Carcinogenic epithelial-mesenchymal transition initiated by oral cancer exosomes is inhibited by anti-EGFR antibody cetuximab

Overexpression and increased signaling from the epidermal growth factor receptor (EGFR) often changes oral squamous cell carcinoma (OSCC) and thus EGFR is frequently targeted molecularly by the therapeutic antibody cetuximab. We assessed the roles of OSCC-derived extracellular vesicles (EVs), including exosomes in the trafficking of cetuximab and in epithelial-mesenchymal transition (EMT) of epithelial cells. OSCC cells abundantly expressed EGFR, which was secreted from cells with OSCC-EVs upon EGF stimulations. The OSCC-EGFR-EVs were then able to enter into and transform epithelial cells leading to increased mesenchymal traits with increased vimentin and spindle-like shapes. EGF priming of OSCC cells further increased this EMT-initiating effect of the OSCC-EVs. The internalization and pro-EMT effects of the OSCC-EVs were largely blocked by cetuximab. Thus, OSCC-derived EVs transform normal epithelial cells into a mesenchymal phenotype and anti-EGFR therapeutic antibody cetuximab inhibits such a carcinogenic effect of the OSCC-EVs.

Dihydroartemisinin represses osteoclastogenesis of bone marrow macrophages through reduced NFATc1 expression and impaired phosphorylation of IκBα

Osteoclasts are multinucleated bone resorbing cells whose differentiation is regulated by several important signaling pathways. Several lines of evidence indicate that dihydroartemisinin (DHA), an anti-malarial drug, inhibits osteoclast differentiation with little cytotoxicity. However, the detailed inhibitory mechanisms of DHA on osteoclastogenesis from native cells remain to be elucidated. In this study, we investigated the effects of DHA on the differentiation of bone marrow-derived macrophages into osteoclasts. DHA inhibited receptor activator of nuclear factor κ-B ligand (RANKL)-induced osteoclast formation and its bone resorbing activity. Mechanistically, DHA treatment markedly abolished phosphorylation of IκBα, and slightly affected a p38 MAPK dependent pathway. Moreover, DHA treatment induced down-regulation of nuclear factor of activated T cells cytoplasmic-1 (NFATc1), a master regulator for osteoclast differentiation and its target proteins, such as Src and cathepsin K. These results indicate that DHA represses RANKL-induced osteoclastogenesis of bone marrow macrophages through reduced NFATc1 expression and impaired phosphorylation of IκBα.

Anti-EGFR antibody cetuximab is secreted by oral squamous cell carcinoma and alters EGF-driven mesenchymal transition

Genetic amplification, overexpression, and increased signaling from the epidermal growth factor receptor (EGFR) are often found in oral squamous cell carcinoma (OSCC) and thus EGFR is frequently targeted molecularly by the therapeutic antibody cetuximab. We assessed effects of cetuximab in control of EGF-driven malignant traits of OSCC cells. EGF stimulation promoted progression level of mesenchymal traits in OSCC cells, which were attenuated by cetuximab but incompletely. We pursued a potential mechanism underlying such incomplete attenuation of OSCC malignant traits. Cetuximab promoted secretion of EGFR-EVs by OSCC cells and failed to inhibit EGF-driven secretion of EGFR-EVs. Cetuximab was also found to be robustly secreted with the EGFR-EVs by the OSCC cells. Thus, EGF promotes the level of mesenchymal traits of OSCC cells and secretion of EGFR-EVs, which involve cetuximab resistance.

Actin binding LIM 1 (abLIM1) negatively controls osteoclastogenesis by regulating cell migration and fusion

Actin binding LIM 1 (abLIM1) is a cytoskeletal actin-binding protein that has been implicated in interactions between actin filaments and cytoplasmic targets. Previous biochemical and cytochemical studies have shown that abLIM1 interacts and co-localizes with F-actin in the retina and muscle. However, whether abLIM1 regulates osteoclast differentiation has not yet been elucidated. In this study, we examined the role of abLIM1 in osteoclast differentiation and function. We found that abLIM1 expression was upregulated during receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast differentiation, and that a novel transcript of abLIM1 was exclusively expressed in osteoclasts. Overexpression of abLIM1 in the murine monocytic cell line, RAW-D suppressed osteoclast differentiation and decreased expression of several osteoclast-marker genes. By contrast, small interfering RNA-induced knockdown of abLIM1 enhanced the formation of multinucleated osteoclasts and markedly increased the expression of the osteoclast-marker genes. Mechanistically, abLIM1 regulated the localization of tubulin, migration, and fusion in osteoclasts. Thus, these results indicate that abLIM1 negatively controls osteoclast differentiation by regulating cell migration and fusion mediated via actin formation.

HSP-enriched properties of extracellular vesicles involve survival of metastatic oral cancer cells

Cancer cells often secrete extracellular vesicles (EVs) that carry heat shock proteins (HSPs) with roles in tumor progression. Oral squamous cell carcinoma (OSCC) belongs to head and neck cancers (HNC) whose lymph-node-metastases often lead to poor prognosis. We have examined the EV proteome of OSCC cells and found abundant secretion of HSP90-enriched EVs in lymph-node-metastatic OSCC cells. Double knockdown of HSP90α and HSP90β, using small interfering RNA significantly reduced the survival of the metastatic OSCC cells, although single knockdown of each HSP90 was ineffective. Elevated expression of these HSP90 family members was found to correlate with poor prognosis of HNC cases. Thus, elevated HSP90 levels in secreted vesicles are potential prognostic biomarkers and therapeutic targets in metastatic OSCC.

Transcription factor EB influences invasion and migration in oral squamous cell carcinomas

OBJECTIVE

Transcription factor EB (TFEB) is a master regulator of lysosomal biogenesis and plays an important role in various cancers. However, the function of TFEB in oral squamous cell carcinomas has not been examined. The aim of this study was to elucidate the role of TFEB in oral squamous cell carcinomas.

MATERIALS AND METHODS

Expression levels of TFEB were examined in six different human oral squamous carcinoma cells: HSC2, HSC3, HSC4, SAS, OSC20, and SCC25. Knockdown of TFEB using small interfering RNA in HSC2 and HSC4 cells was performed. Cell morphology was observed by immunofluorescence microscopy. Cell proliferation, invasion, and adhesion were analyzed.

RESULTS

Expression levels of TFEB were high in HSC2, moderate in HSC4 and SCC25, and low in HSC3 and OSC20 cells. Knockdown of TFEB did not affect proliferation of HSC2 and HSC4 cells, but did induced enlargement of lysosomes and endosomes in HSC4 cells. TFEB silencing reduced invasion and migration of these HSC cell squamous carcinoma cells; however, increased cell adhesion was also observed.

CONCLUSION

TFEB knockdown reduces invasion and migration of cancer cells, likely through lysosomal regulation. Taken together, TFEB influences cell invasion and migration of oral squamous cell carcinomas.