“Cell-in-cell” denotes an invasive phenotype in which one cell actively internalizes in another. The novel human T-cell line HOZOT, established from human umbilical cord blood, was shown to penetrate a variety of human cancer cells but not normal cells. Oncolytic viruses are emerging as biological therapies for human cancers; however, efficient viral delivery is limited by a lack of tumor-specific homing and presence of pre-existing or therapy-induced neutralizing antibodies. Here, we report a new, intriguing approach using HOZOT cells to transmit biologics such as oncolytic viruses into human cancer cells by cell-in-cell invasion. HOZOT cells were successfully loaded via human CD46 antigen with an attenuated adenovirus containing the fiber protein of adenovirus serotype 35 (OBP-401/F35), in which the telomerase promoter regulates viral replication. OBP-401/F35–loaded HOZOT cells were efficiently internalized into human cancer cells and exhibited tumor-specific killing by release of viruses, even in the presence of anti-viral neutralizing antibodies. Moreover, intraperitoneal administration of HOZOT cells loaded with OBP-401/F35 significantly suppressed peritoneally disseminated tumor growth in mice. This unique cell-in-cell property provides a platform for selective delivery of biologics into human cancer cells, which has important implications for the treatment of human cancers.
Contrast variation small-angle neutron scattering by dynamic nuclear polarization is applied to industrial multi-component nanocomposites.
Dynamic nuclear polarization (DNP) at low temperature (1.2 K) and high magnetic field (3.3 T) was applied to a contrast variation study in small-angle neutron scattering (SANS) focusing on industrial rubber materials. By varying the scattering contrast by DNP, time-of-flight SANS profiles were obtained at the pulsed neutron source of the Japan Proton Accelerator Research Complex (J-PARC). The concentration of a small organic molecule, (2,2,6,6-tetramethylpiperidine-1-yl)oxy (TEMPO), was carefully controlled by a doping method using vapour sorption into the rubber specimens. With the assistance of microwave irradiation (94 GHz), almost full polarization of the paramagnetic electronic spin of TEMPO was transferred to the spin state of hydrogen (protons) in the rubber materials to obtain a high proton spin polarization (P
H). The following samples were prepared: (i) a binary mixture of styrene–butadiene random copolymer (SBR) with silica particles (SBR/SP); and (ii) a ternary mixture of SBR with silica and carbon black particles (SBR/SP/CP). For the binary mixture (SBR/SP), the intensity of SANS significantly increased or decreased while keeping its q dependence for P
H = −35% or P
H = 40%, respectively. The q behaviour of SANS for the SBR/SP mixture can be reproduced using the form factor of a spherical particle. The intensity at low q (∼0.01 Å−1) varied as a quadratic function of P
H and indicated a minimum value at P
H = 30%, which can be explained by the scattering contrast between SP and SBR. The scattering intensity at high q (∼0.3 Å−1) decreased with increasing P
H, which is attributed to the incoherent scattering from hydrogen. For the ternary mixture (SBR/SP/CP), the q behaviour of SANS was varied by changing P
H. At P
H = −35%, the scattering maxima originating from the form factor of SP prevailed, whereas at P
H = 29% and P
H = 38%, the scattering maxima disappeared. After decomposition of the total SANS according to inverse matrix calculations, the partial scattering functions were obtained. The partial scattering function obtained for SP was well reproduced by a spherical form factor and matched the SANS profile for the SBR/SP mixture. The partial scattering function for CP exhibited surface fractal behaviour according to q
−3.6, which is consistent with the results for the SBR/CP mixture.
small-angle neutron scattering (SANS); contrast variation; dynamic nuclear polarization; ternary mixtures; nanocomposites
Stomach cancer carcinomatosis peritonitis (SCCP) is a recalcitrant disease. The goal of the present study was to establish an in vitro-in vivo-like imageable model of SCCP to develop cell-cycle-based therapeutics of SCCP. We established 3-D Gelfoam® histoculture and tumor-sphere models of SCCP. FUCCI-expressing MKN-45 stomach cancer cells were transferred to express the fluorescence ubiquinized cell-cycle indicator (FUCCI). FUCCI-expressing MKN-45 cells formed spheres on agarose or on Gelfoam® grew into tumor-like structures with G0/G1 cancer cells in the center and S/G2 cancer cells located in the surface as indicated by FUCCI imaging when the cells fluoresced red or green, respectively. We treated FUCCI-expressing cancer cells forming SCCP tumors in Gelfoam® histoculture with OBP-301, cisplatinum (CDDP), or paclitaxel. CDDP or paclitaxel killed only cycling cancer cells and were ineffective against G1/G2 MKN-45 cells in tumors growing on Gelfoam®. In contrast, the telomerase-dependent adenovirus OBP-301 decoyed the MKN-45 cells in tumors on Gelfoam® to cycle from G0/G1 phase to S/G2 phase and reduced their viability. CDDP- or paclitaxel-treated MKN-45 tumors remained quiescent and did not change in size. In contrast, OB-301 reduced the size of the MKN-45 tumors on Gelfoam®. We examined the cell cycle-related proteins using Western blotting. CDDP increased the expression of p53 and p21 indicating cell cycle arrest. In contrast, OBP-301 decreased the expression of p53 and p21 Furthermore, OBP-301 increased the expression of E2F and pAkt as further indication of cell cycle decoy. This 3-D Gelfoam® histoculture and FUCCI imaging are powerful tools to discover effective therapy of SCCP such as OBP-301.
Malignant melanoma requires precise resection in order to avoid metastatic recurrence. We report here that the telomerase-dependent, green fluorescent protein (GFP)-containing adenovirus OBP-401 could label malignant melanoma with GFP in situ in orthotopic mouse models. OBP-401-based fluorescence-guided surgery (FGS) resulted in the complete resection of malignant melanoma in the orthotopic models, where conventional bright-light surgery (BLS) could not. High-dose administration of OBP-401 enabled FGS without residual cancer cells or recurrence, due to its dual effect of cancer-cell labeling with GFP and killing.
melanoma; nude mice; fluorescence-guided surgery (FGS); adenovirus; OBP-401
Fluorescence-guided surgery (FGS) of cancer is an area of intense development. In the present report, we demonstrate that the telomerase-dependent green fluorescent protein (GFP)-containing adenovirus OBP-401 could label colon-cancer liver metastasis in situ in an orthotopic mouse model enabling successful FGS. OBP-401-GFP-labeled liver metastasis resulted in complete resection with FGS, in contrast, conventional bright-light surgery (BLS) did not result in complete resection of the metastasis. OBP-401-FGS reduced the recurrence rate and prolonged over-all survival compared with BLS. In conclusion, adenovirus OBP-401 is a powerful tool to label liver metastasis in situ with GFP which enables its complete resection, not possible with conventional BLS.
The phase of the cell cycle can determine whether a cancer cell can respond to a given drug. We previously reported monitoring of real-time cell cycle dynamics of cancer cells throughout a live tumor, intravitally in live mice, using a fluorescence ubiquitination-based cell-cycle indicator (FUCCI). Approximately 90% of cancer cells in the center and 80% of total cells of an established tumor are in G0/G1 phase. Longitudinal real-time imaging demonstrated that cytotoxic agents killed only proliferating cancer cells at the surface and, in contrast, had little effect on quiescent cancer cells, which are the vast majority of an established tumor. Moreover, resistant quiescent cancer cells restarted cycling after cessation of chemotherapy. These results suggested why most drugs currently in clinical use, which target cancer cells in S/G2/M, are mostly ineffective on solid tumors. In the present report, we used FUCCI imaging and Gelfoam® collagen-sponge-gel histoculture, to demonstrate in real time, that the cell-cycle phase distribution of cancer cells in Gelfoam® and in vivo tumors is highly similar, whereby only the surface cells proliferate and interior cells are quiescent in G0/G1. This is in contrast to 2D culture where most cancer cells cycle. Similarly, the cancer cells responded similarly to toxic chemotherapy in Gelfoam® culture as in vivo, and very differently than cancer cells in 2D culture which were much more chemosensitive. Gelfoam® culture of FUCCI-expressing cancer cells offers the opportunity to image the cell cycle of cancer cells continuously and to screen for novel effective therapies to target quiescent cells, which are the majority in a tumor and which would have a strong probability to be effective in vivo.
cell cycle; chemotherapy; FUCCI; Gelfoam®; GFP; imaging; RFP; stomach cancer; Three dimensional-histoculture culture
Precise fluorescence-guided surgery (FGS) for pancreatic cancer has the potential to greatly improve the outcome in this recalcitrant disease. In order to achieve this goal, we have used genetic reporters to color code cancer and stroma cells in a patient-derived orthotopic xenograft (PDOX) model. The telomerase-dependent green fluorescent protein (GFP) containing adenovirus OBP401 was used to label the cancer cells of the pancreatic cancer PDOX. The PDOX was previously grown in a red fluorescent protein (RFP) transgenic mouse that stably labeled the PDOX stroma cells bright red. The color-coded PDOX model enabled FGS to completely resect the pancreatic tumors including stroma. Dual-colored FGS significantly prevented local recurrence, which bright-light surgery (BLS) or single color could not. FGS, with color-coded cancer and stroma cells has important potential for improving the outcome of recalcitrant cancer.
fluorescence-guided surgery (FGS); patient-derived orthotopic xenograft (PDOX); adenovirus OBP-401; green fluorescent protein; GFP; red fluorescent protein; RFP; pancreatic cancer; stroma; color-coded fluorescence imaging
Quiescent cancer cells are resistant to cytotoxic agents which target only proliferating cancer cells. Time-lapse imaging demonstrated that tumor-targeting Salmonella typhimurium A1-R (A1-R) decoyed cancer cells in monolayer culture and in tumor spheres to cycle from G0/G1 to S/G2/M, as demonstrated by fluorescence ubiquitination-based cell cycle indicator (FUCCI) imaging. A1-R infection of FUCCI-expressing subcutaneous tumors growing in nude mice also decoyed quiescent cancer cells, which were the majority of the cells in the tumors, to cycle from G0/G1 to S/G2/M, thereby making them sensitive to cytotoxic agents. The combination of A1-R and cisplatinum or paclitaxel reduced tumor size compared with A1-R monotherapy or cisplatinum or paclitaxel alone. The results of this study demonstrate that A1-R can decoy quiescent cancer cells to cycle to S/G2/M and sensitize them to cytotoxic chemotherapy. These results suggest a new paradigm of bacterial-decoy chemotherapy of cancer.
cell cycle; chemotherapy; decoy; FUCCI; GFP; RFP; imaging; S. typhimurium A1-R; tumor-targeting bacteria
Current methods of image-guided surgery of tumours of the lung mostly rely on CT. A sensitive procedure of selective tumour fluorescence labelling would allow simple and high-resolution visualisation of the tumour for precise surgical navigation.
Human lung cancer cell lines H460 and A549 were genetically transformed to express red fluorescent protein (RFP). Tumours were grown subcutaneously for each cell line and harvested and minced for surgical orthotopic implantation on the left lung of nude mice. Tumour growth was measured by fluorescence imaging. After the tumours reached 5 mm in diameter, they were injected under fluorescence guidance with the telomerase-dependent green fluorescent protein (GFP)-containing adenovirus, OBP-401. Viral labelling of the lung tumours with GFP precisely colocalised with tumour RFP expression. Three days after administration of OBP-401, fluorescence-guided surgery (FGS) was performed.
FGS of tumours in the lung was enabled by labelling with a telomerase-dependent adenovirus containing the GFP gene. Tumours in the lung were selectively and brightly labelled. FGS enabled complete lung tumour resection with no residual fluorescent tumour.
FGS of tumours in the lung is feasible and more effective than bright-light surgery.
Lung Cancer; Thoracic Surgery; Imaging/CT MRI etc; Non-Small Cell Lung Cancer
The phase of the cell cycle can determine whether a cancer cell can respond to a given drug. We report here on the results of monitoring of real-time cell cycle dynamics of cancer cells throughout a live tumor intravitally using a fluorescence ubiquitination cell cycle indicator (FUCCI) before, during, and after chemotherapy. In nascent tumors in nude mice, approximately 30% of the cells in the center of the tumor are in G0/G1 and 70% in S/G2/M. In contrast, approximately 90% of cancer cells in the center and 80% of total cells of an established tumor are in G0/G1 phase. Similarly, approximately 75% of cancer cells far from (>100 µm) tumor blood vessels of an established tumor are in G0/G1. Longitudinal real-time imaging demonstrated that cytotoxic agents killed only proliferating cancer cells at the surface and, in contrast, had little effect on quiescent cancer cells, which are the vast majority of an established tumor. Moreover, resistant quiescent cancer cells restarted cycling after the cessation of chemotherapy. Our results suggest why most drugs currently in clinical use, which target cancer cells in S/G2/M, are mostly ineffective on solid tumors. The results also suggest that drugs that target quiescent cancer cells are urgently needed.
drug resistance; cell cycle; tumor; confocal laser microscopy; fluorescent proteins; FUCCI; tumor blood vessels; dormancy
Fluorescence-guided cancer has not yet been shown to be curative due to residual microscopic disease. Human fibrosarcoma HT1080 expressing red fluorescent protein (RFP) was implanted orthotopically in the quadriceps femoris muscle of nude mice. The tumor-bearing mice were injected with high and low-dose telomerase-dependent, green fluorescent protein (GFP)-containing adenovirus OBP-401, which labeled the tumor with GFP. Fluorescence-guided surgery (FGS) or bright light surgery (BLS) was then performed. OBP-401 could label soft-tissue sarcoma (STS) with GFP in situ, concordant with RFP. OBP-401-based FGS resulted in superior resection of STS in the orthotopic model of soft-tissue sarcoma, compared to BLS. High-dose administration of OBP-401 enabled FGS without residual sarcoma cells or local or metastatic recurrence, due to its dual effect of cancer-cell labeling with GFP and killing. High-dose OBP-401 based-FGS improved disease free survival (p = 0.00049) as well as preserved muscle function compared with BLS. High-dose OBP-401-based FGS could cure STS, a presently incurable disease. Since the parent virus of OBP-401, OBP-301, has been previously proven safe in a Phase I clinical trial, it is expected the OBP-401-FGS technology described in the present report should be translatable to the clinic in the near future.
soft tissue sarcoma; nude mice; fluorescence-guided surgery (FGS); adenovirus; OBP-401
Invasive cancer cells are a critical target in order to prevent metastasis. In the present report, we demonstrate real-time visualization of cell cycle kinetics of invading cancer cells in 3-dimensional (3D) Gelfoam® histoculture, which is in vivo-like. A fluorescence ubiquitination cell cycle indicator (FUCCI) whereby G0/G1 cells express a red fluorescent protein and S/G2/M cells express a green fluorescent protein was used to determine the cell cycle position of invading and non-invading cells. With FUCCI 3D confocal imaging, we observed that cancer cells in G0/G1 phase in Gelfoam® histoculture migrated more rapidly and further than cancer cells in S/G2/M phases. Cancer cells ceased migrating when they entered S/G2/M phases and restarted migrating after cell division when the cells re-entered G0/G1. Migrating cancer cells also were resistant to cytotoxic chemotherapy, since they were preponderantly in G0/G1, where cytotoxic chemotherapy is not effective. The results of the present report suggest that novel therapy targeting G0/G1 cancer cells should be developed to prevent metastasis.
FUCCI; 3D; Gelfoam histoculture; cancer invasion; cell cycle kinetics; confocal laser microscopy; fluorescent proteins; real-time imaging
Various cellular stresses activate autophagy, which is involved in lysosomal degradation of cytoplasmic materials for maintaining nutrient homeostasis and eliminating harmful components. Here, we show that RNA polymerase I (Pol I) transcription inhibition induces nucleolar disruption and autophagy. Treatment with autophagy inhibitors or siRNA specific for autophagy-related (ATG) proteins inhibited autophagy but not nucleolar disruption induced by Pol I transcription inhibition, which suggested that nucleolar disruption was upstream of autophagy. Furthermore, treatment with siRNA specific for nucleolar protein nucleophosmin (NPM) inhibited this type of autophagy. This showed that NPM was involved in autophagy when the nucleolus was disrupted by Pol I inhibition. In contrast, NPM was not required for canonical autophagy induced by nutrient starvation, as it was not accompanied by nucleolar disruption. Thus, our results revealed that, in addition to canonical autophagy, there may be NPM-dependent autophagy associated with nucleolar disruption.
The BRAF V600E mutation is reportedly associated with inferior survival among colon cancer patients. Here we report a patient with rectal cancer who carried the novel BRAF mutation VK600–601E, which has analogous molecular functions to those of the conventional BRAF mutation V600E, and may have potential as a prognostic marker for colorectal cancer (CRC).
The present 65-year-old male patient was diagnosed with recurrent rectal adenocarcinoma (stage II by AJCC TNM staging 7th edition) 14 months after surgery and was treated with modified FOLFOX6 (fluorouracil, leucovorin, and oxaliplatin), radiation, and FOLFIRI (fluorouracil, leucovorin, and irinotecan). The tumor progressed before further treatment could be initiated, resulting in death after 15 months. This survival period was similar to the median overall survival among patients with metastatic CRC and BRAF mutations who were treated with the FOLFIRI regimen with or without cetuximab.
Thus, the BRAF VK600–601E mutation may lead to an aggressive clinical course in CRC patients suffering from rapid progression and potential resistance to multiple therapeutic modalities.
Rectal cancer; BRAF mutation; BRAF VK600-601E; Chemotherapy; Prognosis
An intussusception due to colonic adenocarcinoma has sometimes been reported. However, to the best of our knowledge, reports of intussusception due to rectal adenocarcinoma are extremely rare. In this report, the case of a young man with rectal adenocarcinoma causing intussusception is described. A 24-year-old man visited a hospital complaining of abdominal pain, and an upper rectal cancer was diagnosed by colonoscopy. Computed tomography showed intussusception caused by a large tumor in the pelvis and absence of distant metastases. Locally advanced rectal cancer causing intussusception was diagnosed, and a low anterior resection was performed. Intraoperatively, repair of the invagination could not be accomplished easily; therefore, the repair was abandoned. Instead, the tumor was removed en bloc to avoid dissemination of the cancer. Histopathologically, the tumor was diagnosed as a poorly differentiated adenocarcinoma, pStage IIA. The patient has no evidence of recurrence at 10 mo after the operation.
Adult intussusception; En bloc resection; Low anterior resection; Rectal adenocarcinoma; Young cancer
Responding to various stimuli is indispensable for the maintenance of homeostasis. The downregulation of ribosomal RNA (rRNA) transcription is one of the mechanisms involved in the response to stimuli by various cellular processes, such as cell cycle arrest and apoptosis. Cell differentiation is caused by intra- and extracellular stimuli and is associated with the downregulation of rRNA transcription as well as reduced cell growth. The downregulation of rRNA transcription during differentiation is considered to contribute to reduced cell growth. However, the downregulation of rRNA transcription can induce various cellular processes; therefore, it may positively regulate cell differentiation. To test this possibility, we specifically downregulated rRNA transcription using actinomycin D or a siRNA for Pol I-specific transcription factor IA (TIF-IA) in HL-60 and THP-1 cells, both of which have differentiation potential. The inhibition of rRNA transcription induced cell differentiation in both cell lines, which was demonstrated by the expression of the common differentiation marker CD11b. Furthermore, TIF-IA knockdown in an ex vivo culture of mouse hematopoietic stem cells increased the percentage of myeloid cells and reduced the percentage of immature cells. We also evaluated whether differentiation was induced via the inhibition of cell cycle progression because rRNA transcription is tightly coupled to cell growth. We found that cell cycle arrest without affecting rRNA transcription did not induce differentiation. To the best of our knowledge, our results demonstrate the first time that the downregulation of rRNA levels could be a trigger for the induction of differentiation in mammalian cells. Furthermore, this phenomenon was not simply a reflection of cell cycle arrest. Our results provide a novel insight into the relationship between rRNA transcription and cell differentiation.
The noncoding Xist RNA triggers silencing of one of the two female X chromosomes during X inactivation in mammals. Gene silencing by Xist is restricted to a special developmental context in early embryos and specific hematopoietic precursors. Here, we show that Xist can initiate silencing in a lymphoma model. We identify the special AT-rich binding protein SATB1 as an essential silencing factor. Loss of SATB1 in tumor cells abrogates the silencing function of Xist. In lymphocytes Xist localizes along SATB1-organized chromatin and SATB1 and Xist influence each other’s pattern of localization. SATB1 and its homolog SATB2 are expressed during the initiation window for X inactivation in ES cells. Importantly, viral expression of SATB1 or SATB2 enables gene silencing by Xist in embryonic fibroblasts, which normally do not provide an initiation context. Thus, our data establish SATB1 as a crucial silencing factor contributing to the initiation of X inactivation.
Currently-used rodent tumor models, including transgenic tumor models, or subcutaneously growing tumors in mice, do not sufficiently represent clinical cancer. We report here development of methods to obtain a highly clinically-accurate rectal cancer model. This model was established by intrarectal transplantation of mouse rectal cancer cells, stably expressing green fluorescent protein (GFP), followed by disrupting the epithelial cell layer of the rectal mucosa by instilling an acetic acid solution. Early-stage tumor was detected in the rectal mucosa by 6 days after transplantation. The tumor then became invasive into the submucosal tissue. The tumor incidence was 100% and mean volume (±SD) was 1232.4 ± 994.7 mm3 at 4 weeks after transplantation detected by fluorescence imaging. Spontaneous lymph node metastasis and lung metastasis were also found approximately 4 weeks after transplantation in over 90% of mice. This rectal tumor model precisely mimics the natural history of rectal cancer and can be used to study early tumor development, metastasis, and discovery and evaluation of novel therapeutics for this treatment-resistant disease.
A pinhole-type ultra-small-angle X-ray scattering set-up that enlarges the accessible q-range to 0.25 µm−1 is described.
A pinhole-type two-dimensional ultra-small-angle X-ray scattering set-up at a so-called medium-length beamline at SPring-8 is reported. A long sample-to-detector distance, 160.5 m, can be used at this beamline and a small-angle resolution of 0.25 µm−1 was thereby achieved at an X-ray energy of 8 keV.
ultra-small-angle X-ray scattering; hierarchical structures; nanocomposites
This study examines the effects of types of liver resection on the growth of liver and lung metastasis.
Materials and Methods
Experimental liver metastases were established by spleen injection of the Colon 26 murine adenocarcinoma cell line expressing GFP into transgenic nude mice expressing RFP. Experimental lung metastases were established by tail vein injection with Colon 26-GFP. Three days after cell injection, groups of mice underwent liver resection (35%+35% [repeated minor resection] vs. 70% [major resection]). Metastatic tumor growth was measured by color-coded fluorescence imaging of the GFP-expressing cancer cells and RFP-expressing stroma.
Although major and repeated minor resection removed the same volume of liver parenchyma, the two procedures had very different effects on metastatic tumor growth: major resection, stimulated liver and lung metastatic growth as well as recruitment of host-derived stroma compared to repeated minor resection. Repeated minor resection did not stimulate metastasis or stromal recruitment. There was no significant difference in liver regeneration between the two groups. Host-derived stroma density, which is stimulated by major resection compared to repeated minor resection, may stimulate growth in the liver-metastatic tumor. TGF-β is also preferentially stimulated by major resection and may play a role in stroma and metastasis stimulation.
The results of this study indicate that when liver resection is necessary, repeated minor liver resection is superior to major liver resection, since major resection, in contrast to repeated minor resection, stimulates metastasis, which should be taken into consideration in clinical situations indicating liver resection.
Nude mice; liver resection; lung metastasis; liver metastasis; stroma; green fluorescent protein; red fluorescent protein; color-coded imaging
The TGF-β superfamily comprises pleiotropic cytokines that regulate SMAD and non-SMAD signaling. TGF-β–SMAD signal transduction is known to be involved in tissue fibrosis, including renal fibrosis. Here, we found that 1,25-dihydroxyvitamin D3–bound [1,25(OH)2D3-bound] vitamin D receptor (VDR) specifically inhibits TGF-β–SMAD signal transduction through direct interaction with SMAD3. In mouse models of tissue fibrosis, 1,25(OH)2D3 treatment prevented renal fibrosis through the suppression of TGF-β–SMAD signal transduction. Based on the structure of the VDR-ligand complex, we generated 2 synthetic ligands. These ligands selectively inhibited TGF-β–SMAD signal transduction without activating VDR-mediated transcription and significantly attenuated renal fibrosis in mice. These results indicate that 1,25(OH)2D3-dependent suppression of TGF-β–SMAD signal transduction is independent of VDR-mediated transcriptional activity. In addition, these ligands did not cause hypercalcemia resulting from stimulation of the transcriptional activity of the VDR. Thus, our study provides a new strategy for generating chemical compounds that specifically inhibit TGF-β–SMAD signal transduction. Since TGF-β–SMAD signal transduction is reportedly involved in several disorders, our results will aid in the development of new drugs that do not cause detectable adverse effects, such as hypercalcemia.
Tumor suppressor p53 is mutated in a wide variety of human cancers and plays a critical role in anoikis, which is essential for preventing tumorigenesis. Recently, we found that a nucleolar protein, Myb-binding protein 1a (MYBBP1A), was involved in p53 activation. However, the function of MYBBP1A in cancer prevention has not been elucidated.
Relationships between MYBBP1A expression levels and breast cancer progression were examined using patient microarray databases and tissue microarrays. Colony formation, xenograft, and anoikis assays were conducted using cells in which MYBBP1A was either knocked down or overexpressed. p53 activation and interactions between p53 and MYBBP1A were assessed by immunoprecipitation and western blot.
MYBBP1A expression was negatively correlated with breast cancer tumorigenesis. In vivo and in vitro experiments using the breast cancer cell lines MCF-7 and ZR-75-1, which expresses wild type p53, showed that tumorigenesis, colony formation, and anoikis resistance were significantly enhanced by MYBBP1A knockdown. We also found that MYBBP1A binds to p53 and enhances p53 target gene transcription under anoikis conditions.
These results suggest that MYBBP1A is required for p53 activation during anoikis; therefore, it is involved in suppressing colony formation and the tumorigenesis of breast cancer cells. Collectively, our results suggest that MYBBP1A plays a role in tumor prevention in the context of p53 activation.
Breast cancer; Tumorigenesis; Anoikis; p53; MYBBP1A
We have previously developed a telomerase-specific replicating adenovirus expressing GFP (OBP-401), which can selectively label tumors in vivo with GFP. Intraperitoneal (i.p.) injection of OBP-401 specifically labeled peritoneal tumors with GFP, enabling fluorescence visualization of the disseminated disease and real-time fluorescence surgical navigation. However, the technical problems with removing all cancer cells still remain, even with fluorescence-guided surgery. In this study, we report imaging of tumor recurrence after fluorescence-guided surgery of tumors labeled in vivo with the telomerase-dependent, GFP-containing adenovirus OBP-401.. Recurrent tumor nodules brightly expressed GFP, indicating that initial OBP-401-GFP labeling of peritoneal disease was genetically stable, such that proliferating residual cancer cells still express GFP. In situ tumor labeling with a genetic reporter has important advantages over antibody and other non-genetic labeling of tumors, since residual disease remains labeled during recurrence and can be further resected under fluorescence guidance.
green fluorescent protein; adenovirus; cancer labeling; in situ; fluorescence-guided surgery; recurrence; detection
Cancer of the exocrine pancreas is the fourth leading cause of cancer deaths in the United States. Currently, surgical resection is the only hope for cure. The majority of patients present with locally advanced or metastatic disease. The most common site for distant metastasis is the liver. We report here a modified auxotrophic strain of S. typhimurium that can target and control the growth of liver metastasis in a mouse model of pancreatic cancer. This strain of S. typhimurium is auxotrophic (Leucine-arginine dependent) but apparently receives sufficient nutritional support from tumor tissue. To increase tumor targeting ability and tumor killing efficacy, this strain was further modified by re-isolation from a tumor growing in a nude mouse termed A1-R. In the present study, we demonstrate the efficacy of locally- as well as systemically-administered A1-R on liver metastasis of pancreatic cancer. Mice treated with A1-R given locally via intrasplenic injections or systemically via tail-vein injections had a much lower hepatic and splenic tumor burden as compared to control mice. Systemic treatment with intravenous A1-R also increased survival time. All results were statistically significant. This study suggests the clinical potential of bacterial treatment of a critical metastatic target of pancreatic cancer.
Protein ubiquitination is a post-translational protein modification that regulates many biological conditions , , , . Trip12 is a HECT-type E3 ubiquitin ligase that ubiquitinates ARF and APP-BP1 , . However, the significance of Trip12 in vivo is largely unknown. Here we show that the ubiquitin ligase activity of Trip12 is indispensable for mouse embryogenesis. A homozygous mutation in Trip12 (Trip12mt/mt) that disrupts the ubiquitin ligase activity resulted in embryonic lethality in the middle stage of development. Trip12mt/mt embryos exhibited growth arrest and increased expression of the negative cell cycle regulator p16 , , , . In contrast, Trip12mt/mt ES cells were viable. They had decreased proliferation, but maintained both the undifferentiated state and the ability to differentiate. Trip12mt/mt ES cells had increased levels of the BAF57 protein (a component of the SWI/SNF chromatin remodeling complex) and altered gene expression patterns. These data suggest that Trip12 is involved in global gene expression and plays an important role in mouse development.