Evaluation of recombinant human IGF-1/IGFBP-3 on intraventricular hemorrhage prevention and survival in the preterm rabbit pup model.

Insulin-like growth factor-1 (IGF-1) is essential for normal brain development and regulates processes of vascular maturation. The pathogenesis of intraventricular hemorrhage (IVH) relates to the fragility of the immature capillaries in the germinal matrix, and its inability to resist fluctuations in cerebral blood flow. In this work, using different experimental setups, we aimed to (i) establish an optimal time-point for glycerol-induction of IVH in relation to time-point of recombinant human (rh) IGF-1/rhIGFBP-3 administration, and (ii) to evaluate the effects of a physiologic replacement dose of rhIGF-1/rhIGFBP-3 on prevention of IVH and survival in the preterm rabbit pup. The presence of IVH was evaluated using high-frequency ultrasound and post-mortem examinations. In the first part of the study, the highest incidence of IVH (> 60%), occurred when glycerol was administered at the earliest timepoint, e.g., 6 h after birth. At later time-points (18 and 24 h) the incidence decreased substantially. In the second part of the study, the incidence of IVH and mortality rate following rhIGF-1/rhIGFBP-3 administration was not statistically different compared to vehicle treated animals. To evaluate the importance of maintaining intrauterine serum levels of IGF-1 following preterm birth, as reported in human interventional studies, additional studies are needed to further characterize and establish the potential of rhIGF-1/rhIGFBP-3 in reducing the prevalence of IVH and improving survival in the preterm rabbit pup.

Evaluation of enhanced permeability effect and different linear energy transfer of radionuclides in a prostate cancer xenograft model.

We have previously investigated the biodistribution and therapy effect of a humanized monoclonal antibody targeting free prostate-specific antigen (fPSA) intended for theranostics of hormone-refractory prostate cancer. In the present study, we evaluated the off-target effect and different linear energy transfer (LET) radionuclides without the effect of PSA targeting by using an antibody with the same scaffold as previously used immunoconjugates but with random, non-specific, antigen binding region. This allows us to identify alterations generated by specific targeting and those related to passive bystander effects, such as enhanced permeability and retention (EPR). A control humanized IgG monoclonal antibody (hIgG1) and an isotype control IgG monoclonal antibody were conjugated with the chelator CHX-A"-DTPA. The immunoconjugate was radiolabeled with either Lutetium-177 ([177Lu]Lu) or Indium-111 ([111In]In). A biodistribution study in mice carrying LNCaP xenografts, was performed to evaluate the non-specific uptake of [177Lu]Lu-hIgG1 in tumors and normal organs. Further, therapy studies of [177Lu]Lu and [111In]In labeled IgG were performed in BALB/c mice carrying LNCaP xenografts. Tumor tissues of treated xenografts and control were sectioned and immunohistochemically stained for Ki67 and PSA. The highest tumor uptake for the [177Lu]Lu-hIgG1 was seen at 72 hours (7.2±2 %IA/g), when comparing the tumor uptake of the fPSA targeting antibody to the non-specific antibody, the non-specific antibody contributes to half of the tumor uptake at 72 h. The liver uptake was 3.1±0.5 %IA/g at 24 h, 2.8±0.5 %IA/g at 72 h and 1.3±0.6 %IA/g at 120 h in LNCaP xenografts, which was approximately three times lower at 24 h and two times lower at 72 h than for the antibody with preserved targeting. Immunohistochemical labeling showed a reduction of PSA expression and a reduction of Ki67 labeled cells in the [111In]In treated LNCaP tumors, compared to vehicle and [177Lu]Lu treated mice. In conclusion, we found that specific targeting might negatively influence normal organ uptake when targeting secreted antigens. Furthermore, different energy deposition i.e. linear energy transfer of a radionuclide might have diverse effects on receptor expression and cell proliferation in tumors.

A Conjugation Strategy to Modulate Antigen Binding and FcRn Interaction Leads to Improved Tumor Targeting and Radioimmunotherapy Efficacy with an Antibody Targeting Prostate-Specific Antigen.

BACKGROUND: The humanized monoclonal antibody (mAb) hu5A10 specifically targets and internalizes prostate cancer cells by binding to prostate specific antigen (PSA). Preclinical evaluations have shown that hu5A10 is an excellent vehicle for prostate cancer (PCa) radiotheranostics. We studied the impact of different chelates and conjugation ratios on hu5A10's target affinity, neonatal fc-receptor interaction on in vivo targeting efficacy, and possible enhanced therapeutic efficacy. METHODS: In our experiment, humanized 5A10 (hu5A10) was conjugated with DOTA or DTPA at a molar ratio of 3:1, 6:1, and 12:1. Surface plasmon resonance (SPR) was used to study antigen and FcRn binding to the antibody conjugates. [111In]hu5A10 radio-immunoconjugates were administered intravenously into BALB/c mice carrying subcutaneous LNCaP xenografts. Serial Single-photon emission computed tomography (SPECT) images were obtained during the first week. Tumors were harvested and radionuclide distribution was analyzed by autoradiography along with microanatomy and immunohistochemistry. RESULTS: As seen by SPR, the binding to PSA was clearly affected by the chelate-to-antibody ratio. Similarly, FcRn (neonatal fc-receptor) interacted less with antibodies conjugated at high ratios of chelator, which was more pronounced for DOTA conjugates. The autoradiography data indicated a higher distribution of radioactivity to the rim of the tumor for lower ratios and a more homogenous distribution at higher ratios. Mice injected with ratio 3:1 111In-DOTA-hu5A10 showed no significant difference in tumor volume when compared to mice given vehicle over a time period of 3 weeks. Mice given a similar injection of ratio 6:1 111In-DOTA-hu5A10 or 6:1 111In-DTPA-hu5A10 or 12:1 111In-DTPA-hu5A10 showed significant tumor growth retardation. Conclusions: The present study demonstrated that the radiolabeling strategy could positively modify the hu5A10's capacity to bind PSA and complex with the FcRn-receptor, which resulted in more homogenous activity distribution in tumors and enhanced therapy efficacy.

Biodistribution of fluorescence-labelled EGF protein from slow release NanoZolid depots in mouse.

AIM: The study was designed to evaluate the ability of the calcium sulfate based NanoZolid® drug delivery technology to locally release the epidermal growth factor (EGF) protein while maintaining its biological activity. METHODS: NanoZolid-formulated EGF protein labelled with a near infrared dye (EGF-NIR) depots or EGF-NIR dissolved in PBS were injected subcutaneously into mice bearing EGF receptor (EGFR) positive human A549 lung cancer tumors inoculated subcutaneously. The release and biodistribution of the EGF-NIR were investigated in vivo longitudinally up to 96 h post administration, utilizing whole body fluorescence imaging. In order to confirm the in vivo findings, histological analysis of tumor cryosections was performed to investigate EGF-NIR fluorescent signal and EGFR expression level by immunofluorescence labelling. RESULTS: The in vivo fluorescence imaging showed a controlled release profile of the EGF-NIR loaded in the NanoZolid depots compared to free EGF-NIR. Histological analysis of the tumors further demonstrated a prevailing distribution of EGF-NIR in regions with high levels of EGFR expression. CONCLUSION: Calcium sulfate based depots can be used to formulate EGF while maintaining its biological activity, e.g. receptor binding capability. This may have a good clinical potential for local delivery of biomolecules to enhance treatment efficacy and minimize systemic adverse effects.

Integrin α10, a Novel Therapeutic Target in Glioblastoma, Regulates Cell Migration, Proliferation, and Survival.

New, effective treatment strategies for glioblastomas (GBMs), the most malignant and invasive brain tumors in adults, are highly needed. In this study, we investigated the potential of integrin α10ß1 as a therapeutic target in GBMs. Expression levels and the role of integrin α10ß1 were studied in patient-derived GBM tissues and cell lines. The effect of an antibody-drug conjugate (ADC), an integrin α10 antibody conjugated to saporin, on GBM cells and in a xenograft mouse model was studied. We found that integrin α10ß1 was strongly expressed in both GBM tissues and cells, whereas morphologically unaffected brain tissues showed only minor expression. Partial or no overlap was seen with integrins α3, α6, and α7, known to be expressed in GBM. Further analysis of a subpopulation of GBM cells selected for high integrin α10 expression demonstrated increased proliferation and sphere formation. Additionally, siRNA-mediated knockdown of integrin α10 in GBM cells led to decreased migration and increased cell death. Furthermore, the ADC reduced viability and sphere formation of GBM cells and induced cell death both in vitro and in vivo. Our results demonstrate that integrin α10ß1 has a functional role in GBM cells and is a novel, potential therapeutic target for the treatment of GBM.

Protection of Kidney Function with Human Antioxidation Protein α1-Microglobulin in a Mouse 177Lu-DOTATATE Radiation Therapy Model.

AIMS: Peptide receptor radionuclide therapy (PRRT) is in clinical use today to treat metastatic neuroendocrine tumors. Infused, radiolabeled, somatostatin analog peptides target tumors that are killed by irradiation damage. The peptides, however, are also retained in kidneys due to glomerular filtration, and the administered doses must be limited to avoid kidney damage. The human radical scavenger and antioxidant, α1-microglobulin (A1M), has previously been shown to protect bystander tissue against irradiation damage and has pharmacokinetic and biodistribution properties similar to somatostatin analogs. In this study, we have investigated if A1M can be used as a renal protective agent in PRRT. RESULTS: We describe nephroprotective effects of human recombinant A1M on the short- and long-term renal damage observed following lutetium 177 (177Lu)-DOTATATE (150 MBq) exposure in BALB/c mice. After 1, 4, and 8 days (short term), 177Lu-DOTATATE injections resulted in increased formation of DNA double-strand breaks in the renal cortex, upregulated expression of apoptosis and stress response-related genes, and proteinuria (albumin in urine), all of which were significantly suppressed by coadministration of A1M (7 mg/kg). After 6, 12, and 24 weeks (long term), 177Lu-DOTATATE injections resulted in increased animal death, kidney lesions, glomerular loss, upregulation of stress genes, proteinuria, and plasma markers of reduced kidney function, all of which were suppressed by coadministration of A1M. Innovation and Conclusion: This study demonstrates that A1M effectively inhibits radiation-induced renal damage. The findings suggest that A1M may be used as a radioprotector during clinical PRRT, potentially facilitating improved tumor control and enabling more patients to receive treatment.

Stellate cells and mesenchymal stem cells in benign mammary stroma are associated with risk factors for breast cancer - an observational study.

BACKGROUND: It is not known whether stromal cells in benign breast tissue can mediate risk of breast cancer. We recently described aldehyde dehydrogenase 1 A1 (ALDH1) positive (+) cells in morphologically normal breast stroma of premenopausal women, and the data indicated that their distribution is associated with clinical risk factors for breast cancer. The aim of the present study was to define the identities of these cells using histologic and immunohistologic methods, and to investigate associations between those cells and hormonal and genetic risk factors in pre- and postmenopausal women. METHODS: Stroma of morphologically normal tissue was analyzed in samples from 101 well-characterized women whose breasts had been operated. Morphology and immunolabeling were applied to determine cell identities based on the putative stem cell markers ALDH1 and stage-specific embryonic antigen-3 (SSEA3), and immunophenotypes indicating mast cells or stellate cells. The results were compared with the patients' risk factors using regression analysis (two-tailed). RESULTS: ALDH1+ round/oval cells were associated with low parity in BRCA1/2 carriers (p = 0.022), while in non-BRCA1/2-carriers they were negatively associated with nulliparity (p = 0.057). In premenopausal women ALDH1+ round/oval cells were associated with family history (p = 0.058). SSEA3+ round/oval cells were morphologically and immunohistologically consistent with multilineage stress-enduring (Muse) cells, and these cells were independently associated with the breast cancer risk factors low parity (p = 0.015), family history (p = 0.021), and hormone use after menopause (p = 0.032). ALDH1+ spindle-shaped/polygonal cells were immunohistologically consistent with stellate cells, and were negatively associated with family history of breast cancer (p = 0.001). CONCLUSION: This study identified novel stromal cell types in benign breast tissue that have a potential for stratifying women for breast cancer risk.

High Presence of Extracellular Hemoglobin in the Periventricular White Matter Following Preterm Intraventricular Hemorrhage.

Severe cerebral intraventricular hemorrhage (IVH) in preterm infants continues to be a major clinical problem, occurring in about 15-20% of very preterm infants. In contrast to other brain lesions the incidence of IVH has not been reduced over the last decade, but actually slightly increased. Currently over 50% of surviving infants develop post-hemorrhagic ventricular dilatation and about 35% develop severe neurological impairment, mainly cerebral palsy and intellectual disability. To date there is no therapy available to prevent infants from developing either hydrocephalus or serious neurological disability. It is known that blood rapidly accumulates within the ventricles following IVH and this leads to disruption of normal anatomy and increased local pressure. However, the molecular mechanisms causing brain injury following IVH are incompletely understood. We propose that extracellular hemoglobin is central in the pathophysiology of periventricular white matter damage following IVH. Using a preterm rabbit pup model of IVH the distribution of extracellular hemoglobin was characterized at 72 h following hemorrhage. Evaluation of histology, histochemistry, hemoglobin immunolabeling and scanning electron microscopy revealed presence of extensive amounts of extracellular hemoglobin, i.e., not retained within erythrocytes, in the periventricular white matter, widely distributed throughout the brain. Furthermore, double immunolabeling together with the migration and differentiation markers polysialic acid neural cell adhesion molecule (PSA-NCAM) demonstrates that a significant proportion of the extracellular hemoglobin is distributed in areas of the periventricular white matter with high extracellular plasticity. In conclusion, these findings support that extracellular hemoglobin may contribute to the pathophysiological processes that cause irreversible damage to the immature brain following IVH.

The absence of aldehyde dehydrogenase 1 A1-positive cells in benign mammary stroma is associated with risk factors for breast cancer.

In this study, aldehyde dehydrogenase 1 (ALDH1)-expressing cells in stroma of histologically normal breast tissue from premenopausal women were investigated in situ regarding cellular morphology, cell distribution, and relation to the additional stem cell markers, CD44 (+) and CD24 (-). These results were correlated with hormonal and genetic risk factors for breast cancer. Triple immunofluorescence labeling was performed on tissues from premenopausal women with a family history of breast cancer, and breast reduction specimens from premenopausal women with no family history of breast cancer were used as a control group. The majority of ALDH1-immunoreactive cells in stroma were spindle-shaped or polygonal, and such cells that were CD44(-) and CD24(-) were absent in the breast stroma of a significantly larger number of nulliparous than parous women. A less common morphological type of ALDH1-positive cells in stroma was round or oval in shape, and such cells that were CD44(+) and CD24(-) were absent in a significant number of women with a family history of breast cancer. The CD44(+)/CD24(-) immunophenotype is consistent with stem cells, and the round/oval morphology suggests mesenchymal cells. This study demonstrates that there are two morphologically distinct types of ALDH1-positive cells in histologically benign mammary stroma, and the absence of these cells is correlated with clinical risk factors for breast cancer in premenopausal women.

Biodistribution and pharmacokinetics of recombinant α1-microglobulin and its potential use in radioprotection of kidneys.

Peptide-receptor radionuclide therapy (PRRT) is a systemically administrated molecular targeted radiation therapy for treatment of neuroendocrine tumors. Fifteen years of clinical use show that renal toxicity, due to glomerular filtration of the peptides followed by local generation of highly reactive free radicals, is the main side-effect that limits the maximum activity that can be administrated for efficient therapy. α1-microglobulin (A1M) is an endogenous radical scavenger shown to prevent radiation-induced in vitro cell damage and protect non-irradiated surrounding cells. An important feature of A1M is that, following distribution to the blood, it is equilibrated to the extravascular compartments and filtrated in the kidneys. Aiming at developing renal protection against toxic side-effects of PRRT, we have characterized the pharmacokinetics and biodistribution of intravenously (i.v.) injected (125)I- and non-labelled recombinant human A1M and the (111)In- and fluorescence-labelled somatostatin analogue octreotide. Both molecules were predominantly localized to the kidneys, displaying a prevailing distribution in the cortex. A maximum of 76% of the injected A1M and 46% of the injected octreotide were present per gram kidney tissue at 10 to 20 minutes, respectively, after i.v. injection. Immunohistochemistry and fluorescence microscopy revealed a dominating co-existence of the two substances in proximal tubules, with a cellular co-localization in the epithelial cells. Importantly, analysis of kidney extracts displayed an intact, full-length A1M at least up to 60 minutes post-injection (p.i.). In summary, the results show a highly similar pharmacokinetics and biodistribution of A1M and octreotide, thus enabling the use of A1M to protect the kidneys tissue during PRRT.

Adenovirus assembly is impaired by BMI1-related histone deacetylase activity.

Polycomb ring finger oncogene BMI1 (B cell-specific Moloney murine leukemia virus integration site 1) plays a critical role in development of several types of cancers. Here, we report an inverse relationship between levels of BMI1 expression and adenovirus (Ad) progeny production. Enforced BMI1 expression in A549 cells impaired Ad progeny production. In contrast, knocking-down of endogenous BMI1 expression enhanced progeny production of a conditionally replicating Ad and wild-type Ad5 and Ad11p. Ad vectors overexpressing BMI1 were not impaired in the replication of progeny genomes and in the expression of E1A and Ad structural proteins. However, 293 cells infected by Ad vector overexpressing BMI1 contained a large proportion of morphologically irregular Ad particles. This effect was reversed in 293 cells pre-treated with the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) in parallel with the production of infectious Ad particles. Our findings suggest an inhibitory role of BMI1 in Ad morphogenesis that can be implied in Ad tropism and Ad-mediated cancer therapy.

Women with familial risk for breast cancer have an increased frequency of aldehyde dehydrogenase expressing cells in breast ductules.

BACKGROUND: Knowledge is limited regarding the association between stem cells in histologically benign breast tissue and risk factors for breast cancer, and hence we addressed this issue in the present study. Recently, we assessed the histology of benign breast tissue from cancer and non-cancer patients for cells positive for the putative stem cell marker aldehyde dehydrogenase 1 A1 (ALDH), and the findings indicated an association between expression of ALDH and the hormonal factors menopause and hormone therapy. The current investigation examined possible associations between various known clinical and genetic risk factors for breast cancer and cellular expression of ALDH in ductules in benign human breast tissue. METHODS: The study included breast surgery patients that were BRCA1/2 mutation carriers without breast cancer (n = 23), had BRCA1/2 (n = 28) or sporadic (n = 21) breast cancer, or required non-cancer-related mammoplasty (n = 34). The distribution and frequency of ALDH-immunolabelled cells were correlated to patient subgroups with different risk factors, using mammoplasty patients as a control group. Statistical analyses comprised linear and logistic regression, Spearman's rank test, Pearson's test, and Fisher's exact test. In two-tailed tests, p < 0.05 was considered significant. RESULTS: A strong association was found between family history of breast cancer and a high frequency of ALDH+ cells (p = 0.001) at all ductular levels in all groups, regardless of BRCA status, age, parity, or occurrence of cancer. In pre-menopausal non-BRCA cancer patients, the frequency of ALDH+ cells increased with age (p < 0.01) but decreased with increasing parity (p < 0.03). High frequencies of ALDH+ cells were found in the non-basal ductular levels in BRCA1 mutation carriers (p = 0.03), but in the basal ductular level in BRCA2 cancer patients (p = 0.02). Among post-menopausal patients, only on-going hormone replacement therapy was correlated with a high number of ALDH+ cells (p < 0.03). CONCLUSION: In histologically normal breast tissue, we found a positive association between the frequency of ductular ALDH+ cells and several breast cancer risk factors, particularly family history of this disease, which supports previous evidence that ALDH plays a role in breast cancer.

Using intravital microscopy to observe bevacizumab-mediated anti-angiogenesis in human head and neck squamous cell carcinoma xenografts.

CONCLUSION: The study showed the value of using intravital microscopy (IVM) analysis for the study of neoangiogenesis. It demonstrated that the model and the analytical methodology could be used to evaluate in detail the effects of treatment strategies for solid tumours. OBJECTIVES: Neoangiogenesis is a key component of tumour progression, invasion and metastasis. In clinical trials monoclonal antibodies specific for vascular endothelial growth factor - VEGF (bevacizumab) - have been shown to significantly affect tumour progression when given in combination with standard chemotherapy, and also to improve the overall survival of patients. For squamous cell carcinoma of the head and neck (HNSCC), we still await definitive evidence of the effect of such treatment. The present study was designed to investigate the anti-angiogenesis effect of beviacizumab in green fluorescent protein (GFP)-labelled HNSCC xenografts using IVM technology. METHODS: We performed IVM and used image analysis for quantification of angiogenesis and of effects of bevacizumab on cell viability, combined with histochemical and immunohistochemical analysis to standardize the digital analysis of changes in tumour vascularization and cell viability. RESULTS: We found significant effects of bevacizumab on angiogenesis and cancer cell survival in HNSCC. Repeated injections of bevacizumab were found to provide the greatest effects.

Distribution of aldehyde dehydrogenase 1-positive stem cells in benign mammary tissue from women with and without breast cancer.

AIMS: Aldehyde dehydrogenase 1 (ALDH1) in female breast tissue has been linked to stem cells, but little is known about the benign cellular organization in situ. We investigated the distribution of ALDH1-immunoreactive (ALDH1+) cells in histomorphologically benign breast tissue from 28 women with or without breast cancer. METHODS AND RESULTS: ALDH1+ cells were detected in benign tissue of women aged 20-72 years, located most commonly at the luminal and intermediate ductular levels and in the stroma. ALDH1+ cell populations and Ki67+ cell populations were present in separate ductules, both cell types rarely showing epithelial differentiation. ALDH1+ cells were non-reactive to Ki67 and oestrogen receptor. Stromal round/oval ALDH1+ non-leukocyte cells in both age groups expressed contractile protein. There was a lower concentration of luminal and intermediate ductular ALDH1+ cells in postmenopausal women than in premenopausal women, and in cancer patients than in non-cancer patients, and a higher concentration in women receiving exogenous hormones. CONCLUSIONS: This study provides further evidence for the stem cell character of ALDH1+ cells, here in benign breast tissue of cancer and non-cancer patients throughout non-lactating adult life, and contributes evidence of benign stromal ALDH1+ cells. The distribution of ductular ALDH1+ stem cells appears to be influenced by hormonal status.

Acute pyelonephritis and renal scarring are caused by dysfunctional innate immunity in mCxcr2 heterozygous mice.

The CXCR1 receptor and chemokine CXCL8 (IL-8) support neutrophil-dependent clearance of uropathogenic Escherichia coli from the urinary tract. CXCR1 is reduced in children prone to pyelonephritis, and heterozygous hCXCR1 polymorphisms are more common in this patient group than in healthy individuals, strongly suggesting a disease association. Since murine CXCR2 (mCXCR2) is functionally similar to human CXCR1, we determined effects of gene heterozygosity on the susceptibility to urinary tract infection by infecting heterozygous (mCxcr2(+/-)) mice with uropathogenic Escherichia coli. Clearance of infection and tissue damage were assessed as a function of innate immunity in comparison to that in knockout (mCxcr2(-/-)) and wild-type (mCxcr2(+/+)) mice. Acute sepsis-associated mortality was increased and bacterial clearance drastically impaired in heterozygous compared to wild-type mice. Chemokine and neutrophil responses were delayed along with evidence of neutrophil retention and unresolved kidney inflammation 1 month after infection. This was accompanied by epithelial proliferation and subepithelial fibrosis. The heterozygous phenotype was intermediate, between knockout and wild-type mice, but specific immune cell infiltrates that accompany chronic infection in knockout mice were not found. Hence, the known heterozygous CXCR1 polymorphisms may predispose patients to acute pyelonephritis and urosepsis.

HAMLET treatment delays bladder cancer development.

PURPOSE: HAMLET is a protein-lipid complex that kills different types of cancer cells. Recently we observed a rapid reduction in human bladder cancer size after intravesical HAMLET treatment. In this study we evaluated the therapeutic effect of HAMLET in the mouse MB49 bladder carcinoma model. MATERIALS AND METHODS: Bladder tumors were established by intravesical injection of MB49 cells into poly L-lysine treated bladders of C57BL/6 mice. Treatment groups received repeat intravesical HAMLET instillations and controls received alpha-lactalbumin or phosphate buffer. Effects of HAMLET on tumor size and putative apoptotic effects were analyzed in bladder tissue sections. Whole body imaging was used to study HAMLET distribution in tumor bearing mice compared to healthy bladder tissue. RESULTS: HAMLET caused a dose dependent decrease in MB49 cell viability in vitro. Five intravesical HAMLET instillations significantly decreased tumor size and delayed development in vivo compared to controls. TUNEL staining revealed selective apoptotic effects in tumor areas but not in adjacent healthy bladder tissue. On in vivo imaging Alexa-HAMLET was retained for more than 24 hours in the bladder of tumor bearing mice but not in tumor-free bladders or in tumor bearing mice that received Alexa-alpha-lactalbumin. CONCLUSIONS: Results show that HAMLET is active as a tumoricidal agent and suggest that topical HAMLET administration may delay bladder cancer development.

Distribution, cellular localization, and therapeutic potential of the tumor-associated antigen Ku70/80 in glioblastoma multiforme.

Antibodies specifically targeting tumor-associated antigens have proved to be important tools in the treatment of human cancer. A desirable target antigen should be unique to tumor cells, abundantly expressed, and readily available for antibody binding. The Ku70/80 DNA-repair protein is expressed in the nucleus of most cells; it is, however, also present on the cell surface of tumor cell lines, and antibodies binding Ku70/80 at the cell surface were recently shown to internalize into tumor cells. To evaluate the potential of Ku70/80-antigen as a therapeutic target for immunotoxins in glioblastoma multiforme, we investigated binding and localization of Ku70/80-specific antibodies in tissue samples from glioblastomas and normal human brains, and in glioma cell cultures. Furthermore, the internalization and drug-delivery capacity were evaluated by use of immunotoxicity studies. We demonstrate that Ku70/80 is localized on the cell plasma membrane of glioma cell lines, and is specifically present in human glioblastoma tissue. Antibodies bound to the Ku70/80 antigen on the cell surface of glioma cells were found to internalize via endocytosis, and shown to efficiently deliver toxins into glioblastoma cells. The data further imply that different antibodies directed against Ku70/80 possess different abilities to target the antigen, in relation to its presentation on the cell surface or intracellular localization. We conclude that Ku70/80 antigen is uniquely presented on the plasma membrane in glioblastomas, and that antibodies specific against the antigen have the capacity to selectively bind, internalize, and deliver toxins into tumor cells. These results imply that Ku70/80 is a potential target for immunotherapy of glioblastoma multiforme.

Fiber mediated receptor masking in non-infected bystander cells restricts adenovirus cell killing effect but promotes adenovirus host co-existence.

The basic concept of conditionally replicating adenoviruses (CRAD) as oncolytic agents is that progenies generated from each round of infection will disperse, infect and kill new cancer cells. However, CRAD has only inhibited, but not eradicated tumor growth in xenograft tumor therapy, and CRAD therapy has had only marginal clinical benefit to cancer patients. Here, we found that CRAD propagation and cancer cell survival co-existed for long periods of time when infection was initiated at low multiplicity of infection (MOI), and cancer cell killing was inefficient and slow compared to the assumed cell killing effect upon infection at high MOI. Excessive production of fiber molecules from initial CRAD infection of only 1 to 2% cancer cells and their release prior to the viral particle itself caused a tropism-specific receptor masking in both infected and non-infected bystander cells. Consequently, the non-infected bystander cells were inefficiently bound and infected by CRAD progenies. Further, fiber overproduction with concomitant restriction of adenovirus spread was observed in xenograft cancer therapy models. Besides the CAR-binding Ad4, Ad5, and Ad37, infection with CD46-binding Ad35 and Ad11 also caused receptor masking. Fiber overproduction and its resulting receptor masking thus play a key role in limiting CRAD functionality, but potentially promote adenovirus and host cell co-existence. These findings also give important clues for understanding mechanisms underlying the natural infection course of various adenoviruses.

Internalization of cystatin C in human cell lines.

Altered protease activity is considered important for tumour invasion and metastasis, processes in which the cysteine proteases cathepsin B and L are involved. Their natural inhibitor cystatin C is a secreted protein, suggesting that it functions to control extracellular protease activity. Because cystatins added to cell cultures can inhibit polio, herpes simplex and coronavirus replication, which are intracellular processes, the internalization and intracellular regulation of cysteine proteases by cystatin C should be considered. The extension, mechanism and biological importance of this hypothetical process are unknown. We investigated whether internalization of cystatin C occurs in a set of human cell lines. Demonstrated by flow cytometry and confocal microscopy, A-431, MCF-7, MDA-MB-453, MDA-MB-468 and Capan-1 cells internalized fluorophore-conjugated cystatin C when exposed to physiological concentrations (1 microm). During cystatin C incubation, intracellular cystatin C increased after 5 min and accumulated for at least 6 h, reaching four to six times the baseline level. Western blotting showed that the internalized inhibitor was not degraded. It was functionally intact and extracts of cells exposed to cystatin C showed a higher capacity to inhibit papain and cathepsin B than control cells (decrease in enzyme activity of 34% and 37%, respectively). The uptake of labelled cystatin C was inhibited by unlabelled inhibitor, suggesting a specific pathway for the internalization. We conclude that the cysteine protease inhibitor cystatin C is internalized in significant quantities in various cancer cell lines. This is a potentially important physiological phenomenon not previously described for this group of inhibitors.

Combined flow cytometry and confocal laser scanning microscopy for evaluation of BR96 antibody cancer cell targeting and internalization.

BACKGROUND: Monoclonal antibodies (mAb) are important tools in the management of tumor disease, and the discovery of antibodies with both specific cancer cell targeting and capacity to enter the cells by internalization are critical to improve the therapeutic efficacy. METHOD: Antibody cancer cell targeting and internalization properties of fluoroscein-conjugated mAb made against Lewis Y (BR96) were evaluated quantitatively and qualitatively by means of flow cytometry (FCM) and confocal laser scanning microscopy (CLSM), respectively, on cells from a rat tumor cell line (BN7005-H1D2). RESULTS: The study demonstrated a specific binding of BR96 to LewisY (LeY) located in the cell membrane and as BR96/LeY immunocomplexes (BR96/LeY) internalized into the cytoplasm. BR96/LeY was internalized into about 15% of the cells, usually distributed throughout the cytoplasm, but also located close to the nuclei. Cytotoxic effects by BR96 were indicated, and CLSM visualized subpopulations containing cells with bound or internalized BR96/LeY that possessed morphologically pyknotic nuclei and disrupted DNA. CONCLUSION: The spatial-temporal pattern by BR96 cell targeting and internalization processes of BR96/LeY into the cancer cells expressing LeY was demonstrated by FCM and CLSM. Used together, the FCM and CLSM techniques provide a valuable tool for preclinical analyses of antibody targeting and their capacities as carriers of cytotoxic conjugates for the use in cancer therapy.