Hypoxia-activated ADCC-enhanced humanized anti-CD147 antibody for liver cancer imaging and targeted therapy with improved selectivity.

Therapeutic antibodies (Abs) improve the clinical outcome of cancer patients. However, on-target off-tumor toxicity limits Ab-based therapeutics. Cluster of differentiation 147 (CD147) is a tumor-associated membrane antigen overexpressed in cancer cells. Ab-based drugs targeting CD147 have achieved inadequate clinical benefits for liver cancer due to side effects. Here, by using glycoengineering and hypoxia-activation strategies, we developed a conditional Ab-dependent cellular cytotoxicity (ADCC)-enhanced humanized anti-CD147 Ab, HcHAb18-azo-PEG5000 (HAP18). Afucosylated ADCC-enhanced HcHAb18 Ab was produced by a fed-batch cell culture system. Azobenzene (Azo)-linked PEG5000 conjugation endowed HAP18 Ab with features of hypoxia-responsive delivery and selective targeting. HAP18 Ab potently inhibits the migration, invasion, and matrix metalloproteinase secretion, triggers the cytotoxicity and apoptosis of cancer cells, and induces ADCC, complement-dependent cytotoxicity, and Ab-dependent cellular phagocytosis under hypoxia. In xenograft mouse models, HAP18 Ab selectively targets hypoxic liver cancer tissues but not normal organs or tissues, and has potent tumor-inhibiting effects. HAP18 Ab caused negligible side effects and exhibited superior pharmacokinetics compared to those of parent HcHAb18 Ab. The hypoxia-activated ADCC-enhanced humanized HAP18 Ab safely confers therapeutic efficacy against liver cancer with improved selectivity. This study highlights that hypoxia activation is a promising strategy for improving the tumor targeting potential of anti-CD147 Ab drugs.

The combination of NDUFS1 with CD4+ T cell infiltration predicts favorable prognosis in kidney renal clear cell carcinoma.

Background: Kidney renal clear cell carcinoma (KIRC) is an immunogenic tumor, and immune infiltrates are relevant to patients' therapeutic response and prognosis. NDUFS1, the core subunit of mitochondrial complex I, has been reported to be associated with KIRC patients' prognosis. However, the upstream regulator for NDUFS1 and their correlations with immune infiltration remain unclear. Methods: The expression of NDUFS genes in KIRC and their influences on patients' survival were investigated by UALCAN, ENCORI, Oncomine, TIMER as well as Kaplan-Meier Plotter. miRNAs regulating NDUFS1 were predicted and analyzed by TargetScan and ENCORI. The correlations between NDUFS1 expression and immune cell infiltration or gene marker sets of immune infiltrates were analyzed via TIMER. The overall survival in high/low NDUFS1 or hsa-miR-320b expressed KIRC patients with or without immune infiltrates were analyzed via Kaplan-Meier Plotter. The combined NDUFS1 expression and/or CD4+ T cell infiltration on KIRC patients' overall survival were validated by multiplexed immunofluorescence (mIF) staining in tissue microarray (TMA). Furthermore, the influences of NDUFS1 expression on the chemotaxis of CD4+ T cells to KIRC cells were performed by transwell migration assays. Results: We found that the low expression of NDUFS1 mRNA and protein in KIRC was correlated with unfavorable patients' survival and poor infiltration of CD4+ T cells. In patients with decreased CD4+ T cell infiltration whose pathological grade less than III, TMA mIF staining showed that low expression of NDUFS1 had significantly poor OS than that with high expression of NDUFS1 did. Furthermore, hsa-miR-320b, a possible negative regulator of NDUFS1, was highly expressed in KIRC. And, low NDUFS1 or high hsa-miR-320b consistently correlated to unfavorable outcomes in KIRC patients with decreased CD4+ T cell infiltration. In vitro, NDUFS1 overexpression significantly increased the chemotaxis of CD4+ T cell to KIRC cells. Conclusion: Together, NDUFS1, upregulated by decreased hsa-miR-320b expression in KIRC patients, might act as a biomarker for CD4+ T cell infiltration. And, the combination of NDUFS1 with CD4+ T cell infiltration predicts favorable prognosis in KIRC.

Prefrontal parvalbumin interneurons deficits mediate early emotional dysfunction in Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease and has an insidious onset. Exploring the characteristics and mechanism of the early symptoms of AD plays a critical role in the early diagnosis and intervention of AD. Here we found that depressive-like behavior and short-term spatial memory dysfunction appeared in APPswe/PS1dE9 mice (AD mice) as early as 9-11 weeks of age. Electrophysiological analysis revealed excitatory/inhibitory (E/I) imbalance in the prefrontal cortex (PFC). This E/I imbalance was induced by significant reduction in the number and activity of parvalbumin interneurons (PV+ INs) in this region. Furthermore, optogenetic and chemogenetic activation of residual PV+ INs effectively ameliorated depressive-like behavior and rescued short-term spatial memory in AD mice. These results suggest the PFC is selectively vulnerable in the early stage of AD and prefrontal PV+ INs deficits play a key role in the occurrence and development of early symptoms of AD.

JLX001 ameliorates cerebral ischemia injury by modulating microglial polarization and compromising NLRP3 inflammasome activation via the NF-κB signaling pathway.

Ischemic stroke is a devastating disease with high morbidity and mortality rates, and the proinflammatory microglia-mediated inflammatory response directly affects stroke outcome. Previous studies have reported that JLX001, a novel compound with a structure similar to that of cyclovirobuxine D (CVB-D), exerts antiapoptotic, anti-inflammatory and antioxidative effects on ischemia-induced brain injury. However, the role of JLX001 in microglial polarization and nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome regulation after ischemic stroke has not been fully investigated. In this study, we used the middle cerebral artery occlusion (MCAO) method to establish a focal cerebral ischemia model and found that JLX001 attenuated the brain infarct size and improved cerebral damage. Moreover, the expression levels of proinflammatory cytokines (interleukin [IL]-1ß and tumor necrosis factor [TNF]-α) were significantly reduced while those of the anti-inflammatory cytokine IL-10 were increased in the JLX001-treated group. Immunofluorescence staining and flow cytometry revealed an increased number of anti-inflammatory phenotypic microglia and a reduced number of proinflammatory phenotypic microglia in JLX001-treated MCAO mice. Western blotting analysis showed that JLX001 inhibited the expression of NLRP3 and proteins related to the NLRP3 inflammasome axis in vivo. Furthermore, JLX001 reduced the number of NLRP3/Iba1 cells in ischemic penumbra tissues. Finally, mechanistic analysis revealed that JLX001 significantly inhibited the expression of proteins related to the NF-κB signaling pathway. Additionally, pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor, ameliorated cerebral ischemia-reperfusion injury by suppressing microglial polarization towards the proinflammatory phenotype and NLRP3 activation in vivo, further suggesting that these protective effects of JLX001 were mediated by inhibition of the NF-κB signaling pathway. These results suggest that JLX001 is a promising therapeutic approach for ischemic stroke.

CD147 receptor is essential for TFF3-mediated signaling regulating colorectal cancer progression.

Major gaps in understanding the molecular mechanisms of colorectal cancer (CRC) progression and intestinal mucosal repair have hampered therapeutic development for gastrointestinal disorders. Trefoil factor 3 (TFF3) has been reported to be involved in CRC progression and intestinal mucosal repair; however, how TFF3 drives tumors to become more aggressive or metastatic and how TFF3 promotes intestinal mucosal repair are still poorly understood. Here, we found that the upregulated TFF3 in CRC predicted a worse overall survival rate. TFF3 deficiency impaired mucosal restitution and adenocarcinogenesis. CD147, a membrane protein, was identified as a binding partner for TFF3. Via binding to CD147, TFF3 enhanced CD147-CD44s interaction, resulting in signal transducer and activator of transcription 3 (STAT3) activation and prostaglandin G/H synthase 2 (PTGS2) expression, which were indispensable for TFF3-induced migration, proliferation, and invasion. PTGS2-derived PGE2 bound to prostaglandin E2 receptor EP4 subtype (PTGER4) and contributed to TFF3-stimulated CRC progression. Solution NMR studies of the TFF3-CD147 interaction revealed the key residues critical for TFF3 binding and the induction of PTGS2 expression. The ability of TFF3 to enhance mucosal restitution was weakened by a PTGS2 inhibitor. Blockade of TFF3-CD147 signaling using competitive inhibitory antibodies or a PTGS2 inhibitor reduced CRC lung metastasis in mice. Our findings bring strong evidence that CD147 is a novel receptor for TFF3 and PTGS2 signaling is critical for TFF3-induced mucosal restitution and CRC progression, which widens and deepens the understanding of the molecular function of trefoil factors.

AIM2 deletion enhances blood-brain barrier integrity in experimental ischemic stroke.

AIMS: Ischemic stroke is a life-threatening disease with limited therapeutic strategies. Blood-brain barrier (BBB) disruption is a critical pathological process that contributes to poor outcomes in ischemic stroke. We previously showed that the microglial inhibition of the inflammasome sensor absent in melanoma 2 (AIM2) suppressed the inflammatory response and protected against ischemic stroke. However, whether AIM2 is involved in BBB disruption during cerebral ischemia is unknown. METHODS: Middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation/reoxygenation (OGD/R) were used to mimic cerebral ischemia in mice and brain microvascular endothelial cells (HBMECs), respectively. The infarct volume, neurological deficits, and BBB permeability were measured in mice after MCAO. Transendothelial electrical resistance (TEER) and neutrophil adhesion to the HBMEC monolayer were assessed after OGD/R treatment. Western blot and immunofluorescence analyses were conducted to evaluate the expression of related proteins. RESULTS: AIM2 was shown to be expressed in brain endothelial cells and upregulated after ischemic stroke in the mouse brain. AIM2 deletion reduced the infarct volume, improved neurological and motor functions, and decreased BBB disruption. In vitro, OGD/R significantly increased the protein levels of AIM2 and ICAM-1 and decreased those of the tight junction (TJ) proteins ZO-1 and occludin. AIM2 knockdown effectively protected BBB integrity by promoting the expression of TJ proteins and decreasing ICAM-1 expression and neutrophil adhesion. Mechanistically, AIM2 knockdown reversed the OGD/R-induced increases in ICAM-1 expression and STAT3 phosphorylation in brain endothelial cells. Furthermore, treatment with the p-STAT3 inhibitor AG490 mitigated the effect of AIM2 on BBB breakdown. CONCLUSION: Our findings indicated that inhibiting AIM2 preserved the BBB integrity after ischemic stroke, at least partially by modulating STAT3 activation and that AIM2 may be a promising therapeutic target for cerebral ischemic stroke.

Generation and Characterization of Fibroblast-Specific Basigin Knockout Mice.

Basigin is a well-known extracellular stimulator of fibroblasts and may confer resistance to apoptosis of fibroblasts in vitro under some pathological status, but its exact function in fibroblasts and the underlying mechanism remain poorly understood. The systematic Basigin gene knockout leads to the perinatal lethality of mice, which limits the delineation of its function in vivo. In this study, we generated a fibroblast-specific Basigin knock-out mouse model and demonstrated the successful deletion of Basigin in fibroblasts. The fibroblast-specific deletion of Basigin did not influence the growth, fertility and the general condition of the mice. No obvious differences were found in the size, morphology, and histological structure of the major organs, including heart, liver, spleen, lung and kidney, between the knockout mice and the control mice. The deletion of Basigin in fibroblasts did not induce apoptosis in the tissues of the major organs. These results provide the first evidence that the fibroblast-specific Basigin knock-out mice could be a useful tool for exploring the function of Basigin in fibroblasts in vivo.

Aberrant Expression of miR-362 Promotes Lung Cancer Metastasis through Downregulation of Sema3A.

miR-362 is a recently discovered member of the microRNA family, and it modulates a variety of physical activities and plays an important role in the occurrence and development of many tumors. However, the biological functions of hsa-miR-362-5p in non-small-cell lung carcinoma (NSCLC) are unknown. Transwell assay and colony formation were used to determine the migration, invasion, and proliferation of NSCLC cells in vitro. A subcutaneous tumor model in nude mice was established to detect NSCLC tumor growth in vivo. The direct binding of miR-362 to the 3'UTR of Semaphorin 3A (Sema3A) was confirmed by luciferase reporter assay. In this study, we found that the level of miR-362 was higher in NSCLC tissues than in adjacent normal tissues and that the level of miR-362 expression was also elevated in five NSCLC cell lines (A549, 95-D, H1299, H292, and H460) relative to a human normal lung epithelial cell line (BEAS2B). Furthermore, miR-362 promoted NSCLC cell invasion, migration, and colony formation in vitro and tumor formation in vivo. Next, we identified the miR-362 target gene Sema3A, which is significantly correlated with metastasis. Sema3A expression was increased in normal tissues relative to NSCLC tissues. This result is consistent with the fact that miR-362 expression is negatively correlated with Sema3A expression in clinical tissue samples and indicated that miR-362 can regulate Sema3A expression in NSCLC cells and consequently affect NSCLC invasion, migration, and colony formation. Taken together, these findings on the newly identified miR-362/Sema3A axis elucidate the molecular mechanism of NSCLC invasion and migration and could lead to a potential therapeutic target in NSCLC treatment.

Disrupting CD147-RAP2 interaction abrogates erythrocyte invasion by Plasmodium falciparum.

Effective vaccines against malaria caused by Plasmodium falciparum are still lacking, and the molecular mechanism of the host-parasite interaction is not fully understood. Here we demonstrate that the interaction of RAP2, a parasite-secreted rhoptry protein that functions in the parasitophorous vacuole formation stage of the invasion, and CD147 on the host erythrocyte is essential for erythrocyte invasion by P falciparum and is independent from all previously identified interactions involved. Importantly, the blockade of the CD147-RAP2 interaction by HP6H8, a humanized CD147 antibody, completely abolished the parasite invasion with both cure and preventative functions in a humanized mouse model. Together with its long half-life on human red blood cells and its safety profile in cynomolgus monkeys, HP6H8 is the first antibody that offers an advantageous approach by targeting a more conserved late-stage parasite ligand for preventing as well as treating severe malaria.

Promoter hypomethylation up-regulates CD147 expression through increasing Sp1 binding and associates with poor prognosis in human hepatocellular carcinoma.

CD147 is a transmembrane glycoprotein overexpressed in human hepatocellular carcinoma (HCC) which could promote HCC progression and metastasis. Promoter methylation is one of the most important processes in gene regulation. In this study, we aim to investigate CD147 promoter methylation status and the correlation with clinicopathological features and prognosis in HCC. CD147 promoter methylation statuses and expression levels in normal and HCC cell lines and 54 paired HCC and adjacent non-tumour (ANT) tissues were, respectively, examined by bisulphite genomic sequencing, methylation-specific PCR, real-time RT-PCR, Western blot and immunohistochemistry. The correlations of promoter methylation statuses with CD147 expression level and the clinicopathological features were statistically analysed in HCC patients. Significantly higher expression of CD147 and significantly lower promoter methylation level were observed in HCC cell lines compared to normal cell lines and tissues control. In vivo and in vitro analysis indicated that demethylation with 5-Aza-2'-deoxycytidine led to increased CD147 expression through enhancing Sp1 binding affinity, and methylation with methyltransferase reduced CD147 transcriptional activity through interfering Sp1 binding. CD147 promoter methylation level in HCC tissues (22.22%) was lower than that in ANT tissues (46.30%; P < 0.05). Within HCC tissues, a significant inverse correlation was observed between CD147 expression and methylation level (r=-0.615). Moreover, HCC patients with unmethylated CD147 promoter had a significantly higher recurrence rate (88.1%versus 58.3%; P < 0.05) and death rate (83.3%versus 50.0%; P < 0.05) than patients with methylated CD147 promoter. In conclusions, promoter hypomethylation up-regulates CD147 expression primarily through increasing Sp1 binding and associates with poor prognosis in HCC patients.

HAb18G (CD147), a cancer-associated biomarker and its role in cancer detection.

AIMS: To evaluate HAb18G/CD147 as a cancer-associated biomarker using its monoclonal antibody HAb18. METHODS AND RESULTS: On immunohistochemical analysis of 28 tissue microarrays and pathological sections of 1117 breast tissue samples, HAb18G/CD147 was expressed in carcinoma with an overall positivity rate of 67.76%, which was significantly higher than that in sarcomas (27.34%, P < 0.0001) and normal epithelial (5.18%, P < 0.0001) and fetal (2.67%, P < 0.0001) tissues. In epithelial tissues from 14 organs, the difference in HAb18G/CD147 expression between normal epithelium and the corresponding carcinoma was also significant (P < 0.05 for each pair). This expression in carcinoma was also found at the mRNA level, suggesting transcriptional level regulation of HAb18G/CD147 expression. In a retrospective study of 106 patients with infiltrating ductal carcinoma of the breast, the level of HAb18G/CD147 expression was positively correlated with tumour recurrence/metastasis (P = 0.0003) and negatively correlated with survival of breast cancer patients (P = 0.002). Multivariable Cox regression analysis showed that HAb18G/CD147 was an independent prognostic factor. CONCLUSIONS: HAb18G/CD147 is significantly expressed in various cancers and appears to have prognostic significance, rendering it a possible cancer-associated biomarker for pathological diagnosis, prognostic evaluation, targeted therapy and radioimmunoimaging of a broad range of cancer types.

A randomized controlled trial of Licartin for preventing hepatoma recurrence after liver transplantation.

UNLABELLED: Orthotopic liver transplantation (OLT) is the only curative therapy of HCC with underlying cirrhosis, but due to HCC metastasis and recurrence, its benefit is limited to a small population who meet the strict selection criteria. We previously reported that Licartin ([131I] mAb HAb18G/CD147) was safe and effective in treating HCC patients, and its antigen, HAb18G/CD147, was closely related to HCC invasion and metastasis. Here, we reported a randomized controlled trial to assess the post-OLT antirecurrence efficacy of Licartin in advanced HCC patients. We randomized 60 post-OLT patients with HCC, who were at tumor stage 3/4 and outside the Milan criteria before OLT, into 2 groups. Three weeks after OLT, the treatment group received 15.4 MBq/kg of Licartin, while the control group received placebo intravenously for 3 times with an interval of 28 days. At 1-year follow-up, the recurrence rate significantly decreased by 30.4% (P = 0.0174) and the survival rate increased by 20.6% (P = 0.0289) in the treatment group, compared with those in the control group. For the control group versus the treatment group, the hazard ratio for recurrence was 3.60 (95% confidence interval [CI], 1.50-8.60) and that for death was 3.87 (95% CI, 1.23-12.21). Licartin treatment also resulted in an earlier decreased AFP level and a longer time of normal AFP level than placebo (P = 0.0016). No Licartin-related toxic effects were observed. CONCLUSION: Licartin is a promising drug for preventing post-OLT tumor recurrence in advanced HCC patients excluded by the currently strict criteria for OLT. HAb18G/CD147 can be a good drug target.

siRNA targeted against HAb18G/CD147 inhibits MMP-2 secretion, actin and FAK expression in hepatocellular carcinoma cell line via ERK1/2 pathway.

HAb18G/CD147 has been identified as a factor that induces MMPs production. SiRNA targeted against HAb18G/CD147 was transfected into FHCC-98 cells (a HCC cell line) to knockdown its expression. The results showed that downregulating HAb18G/CD147 decreased ERK1/2, MMP-2 and FAK levels and inhibited cell motility and invasion, together with rearranged actin stress fiber formation, while had no effects on integrin alpha3beta1 expression. MEK1/2 inhibitor, U0126, inhibited MMP-2, FAK and actin expression in FHCC-98 cell line. The findings indicate that si-HAb18G inhibits gelatinase production, actin and FAK expression in FHCC-98 via an ERK1/2 signaling pathway.

Radioimmunotherapy of human colon cancer xenografts by using 131I labeled-CAb1 F(ab')2.

PURPOSE: Therapeutic efficacy, suitable dose, and administration times of 131I-CAb1 F(ab')2, a new monoclonal antibody therapeutics specifically directed against a cell surface-associated glycoprotein of colon cancer, were investigated in this article. METHODS AND MATERIALS: In human colon cancer xenografts, 131I-CAb1 F(ab')2 at the dose of 125 muCi, 375 muCi, and 1125 muCi were administrated intraperitoneally on Days 6 and 18 after implantation of HR8348 cells with CAb1 high reactivity. Survival time and tumor growth inhibition rate were used to evaluate the efficacy and safety of 131I-CAb1 F(ab')2 in treatment of colon cancer xenografts. RESULTS: Treatment of 125, 375, and 1125 muCi 131I-CAb1 F(ab')2 did not significantly decrease the mean survival time of nude mice when compared with nontreated groups (p = 0.276, 0.865, 0.582, respectively). Moreover, the mean survival times of nude mice receiving 375 muCi and 1125 muCi 131I-CAb1 F(ab')2 were significantly longer than that of 5-FU-treated groups (p = 0.018 and 0.042). Tumor growth inhibition rates of the first therapy were 35.67% and 41.37%, with corresponding 131I-labeled antibody dosage of 375 muCi and 1125 muCi. After single attack dosage, second reinforcement therapy may rise efficacy significantly. Tumor growth inhibition rates of 125 muCi, 375 muCi, and 1125 muCi 131I-labeled antibody on Day 20 posttherapy were 42.65%, 56.56%, and 84.41%, respectively. Histopathology examination revealed that tissue necrosis of various degrees was found in 131I-CAb1 F(ab')2-treated groups. CONCLUSION: 131I-CAb1 F(ab')2 is safe and effective for colon cancer. It may be a novel and potentially adjuvant therapeutics for colon cancer.

Regulation of matrix metalloproteinase production and tumor cell invasion by four monoclonal antibodies against different epitopes of HAb18G/CD147 extracellular domain.

HAb18G/CD147, a membrane spanning molecule and highly expressed in hepatocellular carcinoma (HCC) cells, was shown to stimulate the production of matrix metalloproteinases (MMPs) in the interaction of tumor cells and fibroblasts. Studies on the EMMPRIN/CD147 showed that CD147 extracellular domain is involved in the induction of MMPs. To study the biological molecular function of HAb18G/CD147 extracellular domain (HAb18G/CD147-ED) on production of MMPs following mediated tumor cell invasion, we isolated four novel monoclonal anibodies (MAbs)-1B3, 3B3, HAb18Gedomab1, and HAb18Gedomab2-against HAb18G/CD147-ED by immunization of BALB/c mice with purified HAb18G/CD147-ED fragments, which were efficiently expressed in Escherichia coli. Gelatin zymography and Boyden chamber assays were used to identify the production of MMPs in the co-cultured human fibroblast and HCC cells, and to quantify the migrated cells in the presence of the generated MAbs. The results showed that two MAbs (1B3 and 3B3) inhibited [corrected] the secretion of MMP-2 and [corrected] the HCC cell invasion, whereas the other two MAbs (HAb18Gedomab1 and HAb18Gedomab2) had reverse function [corrected] FCM additive assay showed that four MAbs recognized different epitopes of HAb18G/CD147-ED. Taken together, the results suggest that various regions of HAb18G/CD147-ED participated in the regulation of MMP secretion.

Targeting radioimmunotherapy of hepatocellular carcinoma with iodine (131I) metuximab injection: clinical phase I/II trials.

PURPOSE: HAb18G/CD147 is a hepatocellular carcinoma (HCC)-associated antigen. We developed iodine (131I) metuximab injection (Licartin), a novel 131I-labeled HAb18G/CD147-specific monoclonal antibody Fab'2 fragment, and evaluated its safety, pharmacokinetics, and clinical efficacy on HCC in Phase I/II trials. METHODS AND MATERIALS: In a Phase I trial, 28 patients were randomly assigned to receive the injection in 9.25-, 18.5-, 27.75-, or 37-MBq/kg doses by hepatic artery infusion. In a multicenter Phase II trial, 106 patients received the injection (27.75 MBq/kg) on Day 1 of a 28-day cycle. Response rate and survival rate were the endpoints. RESULTS: No life-threatening toxic effects were found. The safe dosage was 27.75 MBq/kg. The blood clearance fitted a biphasic model, and its half-life was 90.56-63.93 h. In the Phase II trial, the injection was found to be targeted and concentrated to tumor tissues. Of the 73 patients completing two cycles, 6 (8.22%) had a partial response, 14 (19.18%) minor response, and 43 (58.90%) stable disease. The 21-month survival rate was 44.54%. The survival rate of progression-free patients was significantly higher than that of patients with progressive disease after either one or two cycles (p < 0.0001 or p = 0.0019). CONCLUSION: Iodine (131I) metuximab injection is safe and active for HCC patients.

Recombinant chimeric antibody hCAb as a novel anti-human colorectal carcinoma agent.

A new chimeric IgG1 antibody hCAb which could be specifically directed against a cell surface-associated glycoprotein of colorectal cancer cells was prepared by genetic engineering technology in our lab. In this study, we explored the potential therapeutic mechanisms and described the evaluation of hCAb directed against colorectal cancer. The standard 51Cr release assay showed that like many other clinically validated IgG1 monoclonal antibodies, hCAb primarily acts by antibody-dependent cell-mediated cytotoxicity (ADCC). The maximal cell lysis of ADCC induced by hCAb was over 50% in the presence of peripheral blood mononuclear cells (PBMCs). Moreover, in vivo studies showed potent antitumor effects in nude mice with SW480 and Hce-8693 tumor xenografts. The treatment with hCAb induced a dramatic reduction (over 70%) in tumor volume in comparison to untreated control group. Furthermore, during the period of treatment, the animals treated by hCAb did not show signs of wasting or other visible signs of toxicity. No obvious tissue damage in vital organs was detected. The chimeric antibody hCAb may be a promising candidate in the treatment of human colorectal cancer. This study can provide a reference for the potential application of hCAb in clinical trial.

Pharmacokinetics of radioimmunotherapeutic agent of direct labeling mAb 188Re-HAb18.

AIM: To label anti-hepatoma monoclonal antibody (mAb) fragment HAb18 F(ab')2 was labeled with 188Re for the pharmacokinetic model of 188Re-HAb18 F(ab')2 and to evaluate its pharmacokinetic parameters in hepatoma-bearing nude mice. METHODS: HAb18 F(ab')2 was directly labeled with 188Re using 2-mercaptoethanol (2-ME) as reducing agents. Labeling efficiency and immunoreactivity of 188Re-HAb18 F(ab')2 were evaluated by Whatman 3MM paper chromatography and live cell assay, respectively. Biodistribution analysis was also conducted in nude mice bearing human hepatoma in which animals were sacrificed at different time points (1, 4, 18, 24 and 24h) after 188Re-HAb18 F(ab')2 was injected through tail-vein into hepatoma-bearing nude mice. The blood and radioactivity of organs and mass were measured. The concentrations of (188)Re-HAb18 F(ab')2 were evaluated with a pharmacokinetic 3P97 software. RESULTS: The optimum labeling efficiency and immunoreactive fraction were 91.7% and 0.78% respectively. The parameters of 188Re-HAb18 F(ab')2 were: T (1/2),2.29 h;Vd,1.49 x 10(-9)L x Bq(-1);AUC, 20.49 x 10(9)Bq x h x L(-1);CL, 0.45 x 10(-3)L x h(-1). 188Re-HAb18 F(ab')2 could locate specially in hepatoma with high selective reactivity of HAb18 F(ab')2. 188Re-HAb18 F(ab')2 was mainly eliminated by kidney. The maximal tumor to blood ratio was at 48 h,and maximal tumor to liver ratio was at 18 h. CONCLUSION: The pharmacokinetics of 188Re-HAb18 F(ab')2 fit a l-compartment model. 188Re-HAb18 F(ab')2 can be uptaken selectively at the hepatoma site.

Direct technetium-99m labeling of anti-hepatoma monoclonal antibody fragment:a radioimmunoconjugate for hepatocellular carcinoma imaging.

AIM:To directly radiolabel an anti-hepatoma mAb fragment HAb18 F(ab')(2) with (99m)Tc by stannousreduced method, and assess the stability, biodistribution and radioimmun oimaging (R II).METHODS:Immunoreactive fraction was determined according to Lindmo's method. Ellman's reagent was used to determine the number of thiols in the reduced F(ab') (2). Labeling efficiency and homogeneity were measured by paper chromatography, sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. Challenge assay involved the incubation of aliquots of labeled antibody in ethylenediaminetetraacetate (EDTA) and L-cysteine (L-cys) solutions with different molar ratio at 37° for 1h, respectively. Investigations in vivo utilized nude mice bearing human hepatocellular carcinoma (HHCC) xenografts with gamma camera imaging and tissue biodistribution studies at regular intervals.RESULTS:The labeling procedure was finished within 1.5h compared with the pretinning method which would take at least 21h. In vitro studies demonstrated that the radiolabeled mAb fragment was homogeneous and retained its immunoreactivity. Challenge studies indicated that (99m)Tc-labeled HAb18 F(ab') (2) in EDTA is more stable than in L-cys. Imaging and biodistribution showed a significant tumor uptake at 24h post injection of (99m)Tc-labeled HAb18 F(ab') (2). The blood, kidney, liver and tumor uptakes at 24h were 0.56 ± 0.09, 56.45 ± 11.36,1.43 ± 0.27 and 6.57 ± 3.01 (%ID/g) respectively.CONCLUSION:(99m)Tc-HAb18 F(ab') (2) conjugate prepared by this direct method appears to be an effective way to detect hepatoma in nude mice model.