Clinical uses and safety concerns of tyrosine kinase inhibitors with a focus on novel drugs: A narrative review

Objective:To review the safety issues surrounding tyrosine kinase inhibitors (TKIs), specifically, hematological adverse effects, cardiovascular issues, renal adverse effects and nephrotoxicity, endocrine system adverse effects, concerns related to the reproductive system, dermatological and gastrointestinal adverse effects. Data Sources: A literature search was performed through Web of Science, PubMed, Google Scholar, Scopus, and the Food and Drug Administration. Data Summary: Several safety issues have been raised following the use of TKIs. Most TKIs show hematological side effects. Considering cardiovascular toxicities, as opposed to imatinib which is relatively safe, new-generation TKIs may be associated with severe cardiovascular side effects. Both acute and chronic renal failure were reported with TKIs such as gefitinib, imatinib, pazopanib, sorafenib, and sunitinib. Many endocrine adverse effects have been reported including hypercholesterolemia and hypertriglyceridemia (with lorlatinib) and thyroid dysfunction (with dasatinib). TKIs may interfere with fetus implantation, growth, and gonadal development. Females receiving TKIs and encountering unwanted pregnancy may have a normal pregnancy, miscarriage, or an abnormality in the fetus. Skin toxicity has been identified as the most debilitating adverse effect in patients receiving EGFR-TKI. Gastrointestinal side effects are common with TKIs. Diarrhea was the most frequently reported adverse effect of many TKIs. Conclusions: TKIs are increasingly taking up a critical role in the treatment of cancers due to their specific action toward malignant cells compared to conventional cytotoxic chemotherapy. Despite a dramatic improvement in the survival of patients with cancer following approval of TKIs, various early and late adverse effects were reported.

Quercetin ameliorates Di (2-ethylhexyl) phthalate-induced nephrotoxicity by inhibiting NF-κB signaling pathway

This study aimed to evaluate the possible protective effects of quercetin, a natural flavonoid, against nephrotoxicity induced by Di (2-ethylhexyl) phthalate (DEHP) in kidney tissue of rats and human embryonic kidney (HEK) 293 cell line. The HEK-293 cells were treated with different concentrations of quercetin 24 h before treatment with monoethylhexyl phthalate (MEHP). Male rats were treated with 200-mg/kg DEHP, 200-mg/kg DEHP plus quercetin (50 and 100 mg/kg), and 200-mg/kg DEHP plus vitamin E (20 mg/kg) for 45 days by gavage. Quercetin treatment reduced cytotoxicity and oxidative damage inducing by MEHP in HEK-293 cells. The in vivo findings showed that 100-mg/kg quercetin significantly suppressed DEHP-induced kidney damage. For exploring the involved mechanisms, the expressions of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), nuclear factor kappa B (NFκB), and tumor necrosis factor alpha (TNFα) genes were determined via real-time Polymerase chain reaction (PCR) assay. High dose of quercetin significantly decreased the gene expressions of NF-κB and TNFα, whereas the alternations of Nrf2 and HO-1 gene expressions were not significant in quercetin groups in compared with DEHP group. These findings suggested that the suppression of DEHP-induced nephrotoxicity via quercetin is correlated, at least in part, with its potential to regulate NF-κB signaling pathway.

Phytochemical identification, acute and subchronic oral toxicity assessments of hydroalcoholic extract of Acroptilon repens in BALB/c mice: A toxicological and mechanistic study

Acroptilon repens (L.) DC, commonly known as Rhaponticum repens, is a popular traditional phytomedicine. The current study was conducted to evaluate the acute and subchronic toxicity of the hydroalcoholic extract of this herb with regard to its terpenoid contents in a BALB/c mice model and to investigate the toxicity of this medicinal herb. Identification of extract components of the plant was done using gas chromatography (GC)-mass spectrometry. In order to establish the acute toxicity model, a single dose of 2000 mg/kg of the extract was given orally to male mice and in the subchronic toxicity study, the extract was consecutively administered at doses 250, 500, and 1000 mg/kg for 28 days. After 28 and 42 days, signs of toxicity and mortality were observed. Organ weight changes and the toxicity-associated parameters such as biochemical indicators, oxidative stress indices, mitochondrial parameters, apoptosis-associated gene expression levels, and pro-inflammatory cytokines were evaluated along with the histopathological examination. GC analysis showed that the terpenoids are the major components of the extract. The LD50 value (2 g/kg) was obtained in the acute toxicity assay; the subchronic administration caused a significant elevation in the serum biomarkers as well as in the levels of lipid peroxidation, protein carbonyl, and ROS. Besides, significant reductions in the superoxide dismutase and catalase activities were observed. This toxic effect was further confirmed by histological studies, cytokine assay, and gene expression assays. Following the treatment discontinuation, the abnormalities in the values of biochemical parameters and histopathological changes returned to normal. These findings demonstrate that the subchronic administration of the hydroalcoholic extract of A. repens can reversibly cause toxicity by inducing oxidative stress and mitochondrial dysfunction.

Evaluation of Juniperus communis L. seed extract on benign prostatic hyperplasia induced in male Wistar rats

Background

Benign prostatic hyperplasia (BPH) is a common disease which causes various health problems for elderly men such as urinary retention, recurring urinary tract infection and bladder stones. The aim of this study is to evaluate the therapeutic effects of Juniperus communis L. seed extract (JCS) on BPH in male Wistar rats.

Methods

To this end, 30 rats were divided into 5 groups (N = 6): group 1 (vehicle), group 2 (disease control), group 3 (standard medicine; 10 mg/kg finasteride), and groups 4 and 5 were treated with 300 mg/kg and 600 mg/kg of the hydroalcoholic JCS seed extract, respectively. Groups 2, 3, 4 and 5 received testosterone enanthate to induce prostatic hyperplasia. At the end of experimental period (28 days), prostate glands were cut off under anesthesia. Histopathological examination was done and biochemical parameters such as Malondialdehyde, Glutathione and protein carbonyl were also measured. Their body weights were also observed during the study. At the end of the experiment, prostate weights and prostate specific antigen (PSA) levels were measured. Prostate index, inhibition prostate weight and inhibition prostate index were also calculated.

Results

Both histopathological examination and biochemical parameter results showed significant improvements in rats treated with finasteride and 600 mg/kg JCS extract (p < 0.01). In addition, PSA levels showed significant decrease in comparison with the disease group. But acute toxicity test indicated that using JCS extract resulted in an increase in liver enzymes (ALP, LDH, SGOT, SGPT). As a result, the extract should be used with caution.

Conclusions

Oral administration of JCS extract is effective on preventing testosterone-induced benign prostatic hyperplasia.

The Protective Effects of L-Carnitine and Zinc Oxide Nanoparticles Against Diabetic Injury on Sex Steroid Hormones Levels, Oxidative Stress, and Ovarian Histopathological Changes in Rat

Diabetes mellitus is a common chronic metabolic disorder. This study aimed to investigate the effects of co-treatment with L-carnitine (LC) and zinc oxide nanoparticles (ZnONPs) on serum levels of sex hormones, oxidative stress, and ovarian histopathology in streptozotocin (STZ)-induced diabetic rats. Female Wistar rats (n = 56, 180-220 g) received a single intraperitoneal (IP) injection of STZ (65 mg/kg). They were randomly assigned into the following groups: diabetic group (Dia), Dia+Met group (100 mg metformin/kg/day), Dia+LC group (200 mg/kg/day), Dia+ZnONPs group (10 mg/kg/day), and Dia+LC+ZnONPs group (200 mg LC/kg/day and 10 mg ZnONPs/kg/day). Control group (Ctl) received the same volume of STZ solvent. After 21 days of treatment, blood serum was centrifuged for sex hormone assays. The right ovary was used for biochemical analysis, and the left ovary was fixed in 10% neutral buffered formalin for histological assessment. The levels of estradiol, progesterone, FSH, and LH significantly increased in the Dia+ZnONPs+LC group (P < 0.001) compared with the Dia group. Co-treatment with LC and ZnONPs reduced malondialdehyde and carbonyl protein and increased glutathione, catalase, and superoxide dismutase activities in ovarian tissue compared with the Dia group (P < 0.05). Moreover, the number of all ovarian follicles significantly increased in this group compared with the Dia group (P < 0.05). The results of this study indicated that co-treatment with LC and ZnONPs could preserve ovarian function by increasing sex hormones levels and antioxidant activity and decreasing lipid peroxidation in diabetic rats. Therefore, this compound supplementation may improve ovulation and fertility in people with diabetes mellitus.

Risk associations for intestinal parasites in symptomatic and asymptomatic schoolchildren in central Mozambique

OBJECTIVES

Chronic infections by enteric parasites including protist and helminthic species produce long-term sequelae on the health status of infected children. This study assesses potential associations linked with enteric parasite infections in symptomatic and asymptomatic children in Zambézia province, Mozambique.

METHODS

In this prospective cross-sectional study, stool samples and epidemiological questionnaires on demographics and risk associations were collected from symptomatic children (n = 286) from clinical settings and asymptomatic (n = 807) children from 17 schools and creches aged 3‒14 years. We detected enteric parasites using PCR-based methods. We calculated prevalence (adjusted for age, sex, house construction, drinking water, and latrine use) and odds ratios (ORs) for risk associations with logistic regression, after adjusting for district, neighbourhood and symptoms.

RESULTS

Numbers and adjusted prevalence (95% confidence intervals in parentheses) for the symptomatic and asymptomatic populations were Giardia duodenalis 120, 52% (22-82), 339, 42% (25-59); followed by Strongyloides stercoralis 52, 14% (9‒20), 180, 20% (15-25). Risk associations for G. duodenalis included drinking untreated river/spring water, OR 2.91 (1.80-4.70); contact with ducks, OR 14.96 (2.93‒76.31); dogs, OR 1.92 (1.04-3.52); cats, OR 1.73 (1.16-2.59), and a relative with diarrhoea, OR 2.59 (1.54‒4.37). Risk associations for S. stercoralis included having no latrine, OR 2.41 (1.44-4.02); drinking well water, OR 1.82 (1.02-3.25), and increasing age, OR 1.11 (1.04-1.20).

CONCLUSIONS

We found a high prevalence of intestinal parasites regardless of the children's symptoms. Drinking well or river water, domestic animals, and latrine absence were contributing factors of human infections.

The implication of mitochondrial dysfunction and mitochondrial oxidative damage in di (2-ethylhexyl) phthalate induced nephrotoxicity in both in vivo and in vitro models

Di-(2-ethylhexyl) phthalate (DEHP) and its main metabolite, monoethylhexyl phthalic acid (MEHP), are a serious threat to human and animals' health in the current century. However, their exact mechanism to induce nephrotoxicity is not clear. In the current study, we addressed toxic effects of MEHP and DEHP on embryonic human kidney cells (HEK-293 cell line) and kidney tissue of rats, respectively. In the HEK-293, MTT assay and oxidative stress parameters were measured after treatment with different concentrations of MEHP. For in vivo study, rats were treated with different doses of DEHP (50, 100, 200, 400 mg/kg) via gavage administration for 45 days. The renal function biomarkers (BUN and creatinine) were determined in serum of rats. Mitochondrial toxic parameters including MTT, mitochondrial membrane potential (MMP), mitochondrial swelling, and also oxidative stress parameters were measured in isolated kidney mitochondria. Histopathological effects of DEHP were also evaluated in rats' kidneys. We demonstrated that MEHP induced oxidative stress and cytotoxicity in HEK-293 cells in a concentration dependent manner. The administration of DEHP led to histopathological changes in kidney tissue, which concurred with BUN and creatinine alternations in serum of rats. The results of present study showed a significant mitochondrial dysfunction and oxidative stress confirmed by enhancement of mitochondrial swelling, mitochondrial reactive oxygen species (ROS) and malondialdehyde (MDA), and reduction of MMP and mitochondrial glutathione (GSH). Taken together, this study showed that DEHP/MEHP resulted in mitochondrial dysfunction and oxidative damage, which suggest a vital role of mitochondria in DEHP/MEHP-induced nephrotoxicity.

Effect of Prunus Mahaleb L. Seed Extract on Ethylene glycol- and Ammonium Chloride-Induced Urolithiasis in BALB/c Mice

BACKGROUND

Kidney stone disease can be quite painful, recurrent, and affects many people. Despite advances in drug therapy, there is still a need to find effective drugs with fewer complications for long-term treatment of kidney stones and to prevent its recurrence. The present study aimed to evaluate the effect of Prunus Mahaleb L. seed extract on ethylene glycol- and ammonium chloride-induced urolithiasis in BALB/c mice.

METHODS

The Prunus Mahaleb L. seeds were collected in Mashhad (Iran) in June 2017. Urolithiasis was induced in male BALB/c mice by adding ethylene glycol (EG) 0.75% (v/v) and ammonium chloride (AC) 2% (w/v) to their drinking water for 21 consecutive days. A total of 72 animals were randomly divided into six groups of twelve animals each. Group 1 received purified water as control; group 2 received EG+AC in drinking water; groups 3-5 received the extracts by gavage in dosages of 100, 300, 500 mg/kg body weight, respectively; and group 6 received 888 mg/kg Sankol by gavage. Note that urolithiasis was induced in groups 3-6 in the same manner as in group 2. The data were analyzed using GraphPad Prism Software (version 5.01).

RESULTS

The group receiving Prunus Mahaleb L. extract in a 500 mg/kg dose responded better to the treatment and less damage to the kidney tissue was observed. The serum parameters remarkably decreased in the calculi-induced animals. Besides, the acute toxicity test showed that the use of the extract was safe in animals.

CONCLUSION

The results showed that the use of Prunus Mahaleb L. extract effectively prevented the formation of kidney stones.

Atorvastatin attenuates the ovarian damage induced by cyclophosphamide in rat: An experimental study

BACKGROUND

Cyclophosphamide (CP), as an anticancer agent, causes ovarian toxicity and subsequent infertility in women. Atorvastatin (ATV) at a low dose has antioxidant and anti-inflammatory properties.

OBJECTIVE

The aim of this study was to investigate the protective effect of ATV against CP-induced ovarian injury in rat.

MATERIALS AND METHODS

In this experimental study, thirty-two female Wistar rats were randomly divided into four groups as I) control, II) ATV (10 mg/kg), III) CP (150 mg/kg), and IV) CP +ATV. The ATV treated groups were received ATV for 10 days via oral gavage. In the CP+ATV group, ATV was administrated on 5 days before and 5 days after CP injection. Histological structure, apoptosis (caspase-3), oxidative stress parameters as malondialdehyde, reactive oxygen species, protein carbonyl levels and cell viability were evaluated in ovary tissue by histological scores, immunohistochemistry, histochemical and biochemical assays. The levels of estrogen and progesterone hormones were measured on the 12th day of study.

RESULTS

ATV pretreatment significantly decreased the levels of oxidative stress biomarkers as malondialdehyde, reactive oxygen species and protein carbonyl levels and increased cell death in CP-treated rats as compared with the CP alone group. ATV significantly increased estrogen and progesterone levels in CP-treated rats. In addition, the histological examination showed ATV mitigated acute inflammation, degenerative cells in stroma and follicles, stromal edema, vacuolization, atresia of the follicles and congestion of blood vessels in the CP-treated animals. Furthermore, ATV significantly reduced immunoreactivity level of caspase-3 in CP-treated rats.

CONCLUSION

Our results showed that the ATV with antioxidant and anti-apoptosis (caspase-3) activities protected ovarian against CP-induced toxicity.

Atorvastatin mitigates cyclophosphamide-induced hepatotoxicity via suppression of oxidative stress and apoptosis in rat model

Cyclophosphamide (CP), as a chemotherapy drug, induces hepatotoxicity through causing oxidative stress. Atorvastatin (ATV) at a low dose has antioxidant and anti-inflammatory properties. The present study was designed to investigate the protective effects of ATV against CP-induced hepatotoxicity in rat. In this experimental study, 32 rats were treated with ATV orally at a dose of 10 mg/kg for 10 consecutive days, 5 days before and 5 days after the administration of a single intraperitoneal injection of CP (150 mg/kg). The hepatoprotective effect of ATV was evaluated by measuring liver function markers, oxidative markers, histological and immunohistochemical assays. The biochemical results showed that administration of CP increased hepatic biomarkers enzymes as aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels. CP increased malondialdehyde (MDA), protein carbonyl (PC) and decreased glutathione (GSH) content in rats. Moreover, administration of CP was associated with periportal leucocyte infiltration, dilation sinusoids, hepatocyte vacuolation, congestion and hemorrhage in livers of rats. CP significantly increased immunoreactivity of caspase-3 as a marker of apoptosis in liver tissue. ATV markedly mitigated liver injury through reduction in oxidative stress biomarkers, histopathological findings and apoptosis. The antioxidant and anti-apoptotic activities of ATV are main proposed mechanisms involved in its hepatoprotective effects against CP-induced hepatic injury.

Single-particle structure determination by X-ray free-electron lasers: Possibilities and challenges

Single-particle structure recovery without crystals or radiation damage is a revolutionary possibility offered by X-ray free-electron lasers, but it involves formidable experimental and data-analytical challenges. Many of these difficulties were encountered during the development of cryogenic electron microscopy of biological systems. Electron microscopy of biological entities has now reached a spatial resolution of about 0.3 nm, with a rapidly emerging capability to map discrete and continuous conformational changes and the energy landscapes of biomolecular machines. Nonetheless, single-particle imaging by X-ray free-electron lasers remains important for a range of applications, including the study of large "electron-opaque" objects and time-resolved examination of key biological processes at physiological temperatures. After summarizing the state of the art in the study of structure and conformations by cryogenic electron microscopy, we identify the primary opportunities and challenges facing X-ray-based single-particle approaches, and possible means for circumventing them.

Coenzyme Q10 remarkably improves the bio-energetic function of rat liver mitochondria treated with statins

CoQ10 shares a biosynthetic pathway with cholesterol therefore it can be a potential target of the widely available lipid-lowering agents such as statins. Statins are the most widely prescribed cholesterol-lowering drugs with the ability to inhibit HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase. Preclinical and clinical safety data have shown that statins do not cause serious adverse effects in humans. However, their long-term administration is associated with a variety of myopatic complaints. The aim of this study was to investigate whether CoQ10 supplementation of animals under high fat diet (HFD) treated with statins is able to bypass the mitochondrial metabolic defects or not? Animals were divided into 7 groups and fed with either regular (RD) or HFD during experiments. The first group considered as regular control and fed with a RD. Groups 2-7 including HFD control, CoQ10 (10mg/kg), simvastatin (30mg/kg), atorvastatin (30mg/kg), simvastatin+CoQ10 or atorvastatin+CoQ10 treated orally for 30 days and fed with HFD. At the end of treatments, the animals were killed and blood samples were collected for biochemical examinations. The rat liver mitochondria were isolated and several mitochondrial indices including succinate dehydrogenase activity (SDA), ATP levels, mitochondrial membrane potential (MMP) and mitochondrial permeability transition pore (MPP) were determined. We found that triglyceride (Tg), cholesterol (Chol) and low-density lipoprotein (LDL) were augmented with HFD compared to RD and treatment with statins remarkably lowered the Tg, Chol and LDL levels. Mitochondrial parameters including, SDA, ATP levels, MMP and MPP were reduced with statin treatment and improved by co-administration with CoQ10.

High-resolution structure of viruses from random diffraction snapshots

The advent of the X-ray free-electron laser (XFEL) has made it possible to record diffraction snapshots of biological entities injected into the X-ray beam before the onset of radiation damage. Algorithmic means must then be used to determine the snapshot orientations and thence the three-dimensional structure of the object. Existing Bayesian approaches are limited in reconstruction resolution typically to 1/10 of the object diameter, with the computational expense increasing as the eighth power of the ratio of diameter to resolution. We present an approach capable of exploiting object symmetries to recover three-dimensional structure to high resolution, and thus reconstruct the structure of the satellite tobacco necrosis virus to atomic level. Our approach offers the highest reconstruction resolution for XFEL snapshots to date and provides a potentially powerful alternative route for analysis of data from crystalline and nano-crystalline objects.

Anti-angiogenic factors and pre-eclampsia in type 1 diabetic women

AIMS/HYPOTHESIS

Elevated anti-angiogenic factors such as soluble fms-like tyrosine kinase 1 (sFlt1), a soluble form of vascular endothelial growth factor receptor, and endoglin, a co-receptor for TGFbeta1, confer high risk of pre-eclampsia in healthy pregnant women. In this multicentre prospective study, we determined levels of these and related factors in pregnant women with type 1 diabetes, a condition associated with a fourfold increase in pre-eclampsia.

METHODS

Maternal serum sFlt1, endoglin, placental growth factor (PlGF) and pigment epithelial derived factor were measured in 151 type 1 diabetic and 24 healthy non-diabetic women at each trimester and at term.

RESULTS

Approximately 22% of the diabetic women developed pre-eclampsia, primarily after their third trimester visit. In women with pre-eclampsia (diabetic pre-eclampsia, n = 26) vs those without hypertensive complications (diabetic normotensive, n = 95), significant changes in angiogenic factors were observed, predominantly in the early third trimester and prior to clinical manifestation of pre-eclampsia. Serum sFlt1 levels were increased approximately twofold in type 1 diabetic pre-eclampsia vs type 1 diabetic normotensive women at the third trimester visit (p < 0.05) and the normal rise of PlGF during pregnancy was blunted (p < 0.05). Among type 1 diabetic women, third trimester sFlt1 and PlGF were inversely related (r(2) = 42%, p < 0.0001). Endoglin levels were increased significantly in the diabetic group as a whole vs the non-diabetic group (p < 0.0001).

CONCLUSIONS/INTERPRETATION

Higher sFlt1 levels, a blunted PlGF rise and an elevated sFlt1/PlGF ratio are predictive of pre-eclampsia in pregnant women with type 1 diabetes. Elevated endoglin levels in women with type 1 diabetes may confer a predisposition to pre-eclampsia and may contribute to the high incidence of pre-eclampsia in this patient group.

Oxidised, glycated LDL selectively influences tissue inhibitor of metalloproteinase-3 gene expression and protein production in human retinal capillary pericytes

AIMS/HYPOTHESIS

Matrix metalloproteinases (MMPs) and their natural inhibitors, tissue inhibitor of metalloproteinases (TIMPs), regulate important biological processes including the homeostasis of the extracellular matrix, proteolysis of cell surface proteins, proteinase zymogen activation, angiogenesis and inflammation. Studies have shown that their balance is altered in retinal microvascular tissues in diabetes. Since LDLs modified by oxidation/glycation are implicated in the pathogenesis of diabetic vascular complications, we examined the effects of modified LDL on the gene expression and protein production of MMPs and TIMPs in retinal pericytes.

METHODS

Quiescent human retinal pericytes were exposed to native LDL (N-LDL), glycated LDL (G-LDL) and heavily oxidised and glycated LDL (HOG-LDL) for 24 h. We studied the expression of the genes encoding MMPs and TIMPs mRNAs by analysis of microarray data and quantitative PCR, and protein levels by immunoblotting and ELISA.

RESULTS

Microarray analysis showed that MMP1, MMP2, MMP11, MMP14 and MMP25 and TIMP1, TIMP2, TIMP3 and TIMP4 were expressed in pericytes. Of these, only TIMP3 mRNA showed altered regulation, being expressed at significantly lower levels in response to HOG- vs N-LDL. Quantitative PCR and immunoblotting of cell/matrix proteins confirmed the reduction in TIMP3 mRNA and protein in response to HOG-LDL. In contrast to cellular TIMP3 protein, analysis of secreted TIMP1, TIMP2, MMP1 and collagenase activity indicated no changes in their production in response to modified LDL. Combined treatment with N- and HOG-LDL restored TIMP3 mRNA expression to a level comparable with that after N-LDL alone.

CONCLUSIONS/INTERPRETATION

Among the genes encoding for MMPs and TIMPs expressed in retinal pericytes, TIMP3 is uniquely regulated by HOG-LDL. Reduced TIMP3 expression might contribute to microvascular abnormalities in diabetic retinopathy.

Direct Evidence on the Immune-Mediated Spontaneous Regression of Human Cancer: An Incentive for Pharmaceutical Companies to Develop a Novel Anti-Cancer Vaccine

To develop an effective pharmaceutical treatment for a disease, we need to fully understand the biological behavior of that disease, especially when dealing with cancer. The current available treatment for cancer may help in lessening the burden of the disease or, on certain occasions, in increasing the survival of the patient. However, a total eradication of cancer remains the researchers' hope. Some of the discoveries in the field of medicine relied on observations of natural events. Among these events is the spontaneous regression of cancer. It has been argued that such regression could be immunologically-mediated, but no direct evidence has been shown to support such an argument. We, hereby, provide compelling evidence that spontaneous cancer regression in humans is immunologically-mediated, hoping that the results from this study would stimulate the pharmaceutical industry to focus more on cancer vaccine immunotherapy. Our results showed that patients with >3 primary melanomas (very rare group among cancer patients) develop significant histopathological spontaneous regression of further melanomas that they could acquire during their life (P=0.0080) as compared to patients with single primary melanoma where the phenomenon of spontaneous regression is absent or minimal. It seems that such regression resulted from the repeated exposure to the tumor which mimics a self-immunization process. Analysis of the regressing tumors revealed heavy infiltration by T lymphocytes as compared to non-regressing tumors (P<0.0001), the predominant of which were T cytotoxic rather than T helper. Mature dendritic cells were also found in significant number (P<0.0001) in the regressing tumors as compared to the non regressing ones, which demonstrate an active involvement of the different arms of the immune system in the multiple primary melanoma patients in the process of tumor regression. Also, MHC expression was significantly higher in the regressing versus the non-regressing tumors (P <0.0001), which reflects a proper tumor antigen expression. Associated with tumor regression was also loss of the melanoma common tumor antigen Melan A/ MART-1 in the multiple primary melanoma patients as compared to the single primary ones (P=0.0041). Furthermore, loss of Melan A/ MART-1 in the regressing tumors significantly correlated with the presence of Melan A/ MART-1-specific CTLs in the peripheral blood of these patients (P=0.03), which adds to the evidence that the phenomenon of regression seen in these patients was immunologically-mediated and tumor-specific. Such correlation was also seen in another rare group of melanoma patients, namely those with occult primary melanoma. The lesson that we could learn from nature in this study is that inducing cancer regression using the different arms of the immune system is possible. Also, developing a novel cancer vaccine is not out of reach.

Human aspartic protease memapsin 2 cleaves the beta-secretase site of beta-amyloid precursor protein

The cDNAs of two new human membrane-associated aspartic proteases, memapsin 1 and memapsin 2, have been cloned and sequenced. The deduced amino acid sequences show that each contains the typical pre, pro, and aspartic protease regions, but each also has a C-terminal extension of over 80 residues, which includes a single transmembrane domain and a C-terminal cytosolic domain. Memapsin 2 mRNA is abundant in human brain. The protease domain of memapsin 2 cDNA was expressed in Escherichia coli and was purified. Recombinant memapsin 2 specifically hydrolyzed peptides derived from the beta-secretase site of both the wild-type and Swedish mutant beta-amyloid precursor protein (APP) with over 60-fold increase of catalytic efficiency for the latter. Expression of APP and memapsin 2 in HeLa cells showed that memapsin 2 cleaved the beta-secretase site of APP intracellularly. These and other results suggest that memapsin 2 fits all of the criteria of beta-secretase, which catalyzes the rate-limiting step of the in vivo production of the beta-amyloid (Abeta) peptide leading to the progression of Alzheimer's disease. Recombinant memapsin 2 also cleaved a peptide derived from the processing site of presenilin 1, albeit with poor kinetic efficiency. Alignment of cleavage site sequences of peptides indicates that the specificity of memapsin 2 resides mainly at the S(1)' subsite, which prefers small side chains such as Ala, Ser, and Asp.

Mass spectrometric characterization and glycosylation profile of bovine pancreatic bile salt-activated lipase

We developed a procedure for the large scale isolation of bovine bile salt-activated lipase (BAL) for its crystallization [Wang, X., et al. (1997) Structure 5, 1209-1218] and also carried out a study on the molecule's glycosylation profile for a better deduction of the structure of the enzyme. Mass spectrometric analysis of the CNBr-generated peptides indicated that only one (Asn-361) of the two potential N-glycosylation sites (Asn-187 and Asn-361) with NXT motif is glycosylated. The analysis of the isolated CNBr peptide containing Asn-361 showed that it existed in three glycoforms in a ratio of 1.0:2.8:1.0, with oligosaccharide moieties weighing 1900.1, 2045.2, and 2336.4 Da, respectively. The major oligosaccharide chain contained mannose: galactose:N-acetylglucosamine:fucose:sialic acid in a molar ratio of 2:2:4:2:1. It was also determined that the potential O-glycosylated peptide (CB13) is not O-glycosylated and, in addition, it was found that there was microheterogeneity in the C-terminus of the isolated bovine BAL. The results obtained from this mass spectrometric study combined with the X-ray crystallographic studies provide more precise structural information on BAL. The procedure described here for the mass spectrometric analysis of CNBr-generated peptides also has general applicability for analysis of the glycosylation profile of glycoproteins and the C-terminal peptide structure of proteins.

Isolation and characterization of recombinant human apolipoprotein C-II expressed in Escherichia coli

A full-length recombinant human apolipoprotein C-II (ApoC-II) has been successfully expressed in Escherichia coli using the T7 expression system. The recombinant ApoC-II. which was expressed intracellularly in the inclusion bodies, was solubilized with 8 M urea and purified using Sephadex G-75 gel permeation chromatography. Four liters of the bacterial culture yielded 16-20 mg of purified recombinant ApoC-II. Sequencing and mass spectrometric analyses indicated that the isolated recombinant ApoC-II contained predominantly (64%) the native form with threonine as the N-terminus, but also contained a minor (36%) molecular form of ApoC-II with an additional methionine at the N-terminus (Met-ApoC-II). Analysis of the recombinant ApoC-II by tryptic digestion and high performance liquid chromatography-electrospray mass spectrometry provides additional conclusive evidence that, with the exception of the N-terminus of Met-ApoC-II, the expressed ApoC-II has the expected peptide sequence. However, this extra N-terminal methionine residue can be excised by further in vitro treatment with methionine aminopeptidase. The purified recombinant ApoC-II was found to be competent in the activation of bovine milk lipoprotein lipase. Thus, the recombinant ApoC-II prepared from E. coli may have a pharmacological application for the treatment of patients with genetic hypertriglyceridemia caused by ApoC-II deficiency.

Isolation and characterization of human milk bile salt-activated lipase C-tail fragment

Glycosylation positions and oligosaccharide characteristics in the proline-rich, mucin-like, C-terminal region (C-tail) of human milk bile salt-activated lipase (BAL) were studied in order to assess the possible physiological functions of this region. A large-scale purification method has been devised to purify the C-tail fragment from human milk BAL. Chymotryptic, tryptic, and cyanogen bromide cleavages of partially purified BAL and subsequent molecular sieve chromatography yielded 20-30 mg of C-tail fragment from 1 L of human milk. The N-terminal sequence and amino acid composition of the purified C-tail fragment establish that it is derived from residues 528-712 of the enzyme. The O-glycosylated carbohydrates of the C-tail fragment contain fucose, galactose, glucosamine, galactosamine, and neuraminic acid in a molar ratio of 1:3:2:1:0.3, respectively. beta-Elimination reaction revealed that nine threonine residues and less than one serine residue were glycosylated. Edman degradation of C-tail fragment and its pronase subfragment suggest a number of glycosylation sites which are flanked by a consensus motif of PVPP. We suggest that this motif may serve as a signal for O-glycosylation in the C-tail region of BAL. Immunochemical studies indicated that the oligosaccharide chains in the C-tail region of BAL contain Lewis x and Lewis a antigens and, less prominently, sialyl Lewis x and sialyl Lewis a antigens. C-tail fragment was also found to bind jacalin lectin. These observations suggest the possibility that the C-tail region may contribute to adhesive activity in the physiological function of BAL.

Intracellular diversion of glycoprotein GP160 of human immunodeficiency virus to lysosomes as a strategy of AIDS gene therapy

A potential gene therapy strategy against human immunodeficiency virus (HIV-1) is to disrupt the intracellular transport of viral proteins. We report here the binding and transporting of HIV-1 glycoprotein gp160 to lysosomes as a result of the expression of fusion genes consisting of soluble CD4 and lysosome targeting domains. The effective lysosome targeting domain tested includes a lysosomal protease zymogen, procathepsin D, and the COOH-terminal domains of three lysosome membrane proteins: lamp-1, lamp-2, and lysosomal acid phosphatase. We demonstrated that cell fusion (syncytium), caused by the transport of gp160 to the surface of HeLa-CD4+ cells, was completely abolished by the expression of these fusion genes. The lysosomal localization of gp160 in HeLa cells coexpressing CD4-fusion genes was also established. From pulse-chase experiments, we observed that gp160 and the fusion proteins were degraded, as expected of lysosomal activities. Additionally, T lymphoblastoid cells transiently and permanently expressing these fusion genes strongly retarded the propagation of human immunodeficiency virus type 1. Thus, these fusion genes can deprive HIV of newly synthesized envelope protein gp160 for the assembly of new virions and are potentially useful in gene therapy against AIDS.