Regulation of EGFR Protein Stability by the HECT-type Ubiquitin Ligase SMURF2

Epidermal growth factor receptor (EGFR) is overexpressed in a variety of epithelial tumors and is considered to be an important therapeutic target. Although gene amplification is responsible for EGFR overexpression in certain human malignancies including lung and head and neck cancers, additional molecular mechanisms are likely. Here, we report a novel interaction of EGFR with an HECT-type ubiquitin ligase SMURF2, which can ubiquitinate, but stabilize EGFR by protecting it from c-Cbl-mediated degradation. Conversely, small interfering RNA (siRNA)-mediated knockdown of SMURF2 destabilized EGFR, induced an autophagic response and reduced the clonogenic survival of EGFR-expressing cancer cell lines, with minimal effects on EGFR-negative cancer cells, normal fibroblasts, and normal epithelial cells. UMSCC74B head and neck squamous cancer cells, which form aggressive tumors in nudemice, significantly lost in vivo tumor-forming ability on siRNA-mediated SMURF2 knockdown. Gene expressionmicroarray data from 443 lung adenocarcinoma patients, and tissue microarray data from 67 such patients, showed a strong correlation of expression between EGFR and SMURF2 at the messenger RNA and protein levels, respectively. Our findings suggest that SMURF2-mediated protective ubiquitination of EGFR may be responsible for EGFR overexpression in certain tumors and support targeting SMURF2-EGFR interaction as a novel therapeutic approach in treating EGFR-addicted tumors.     

Oral delivery of proteins: progress and prognostication

The delivery of proteins has gained momentum with the development of biotechnology sector that provided large-scale availability of therapeutic proteins. The availability is mostly due to the advances in recombinant DNA technology. The low oral bioavailability, however, continues to be a problem for several proteins because of their large molecular size, low permeation through biological membranes, and susceptibility to molecular changes in both biological and physical environments. The demand for effective delivery of proteins by the oral route has brought a tremendous thrust in recent years both in the scope and complexity of drug delivery technology. The important therapeutic proteins and peptides being explored for oral delivery include insulin, calcitonin, interferons, human growth hormone, glucagons, gonadotropin-releasing hormones, enkephalins, vaccines, enzymes, hormone analogs, and enzyme inhibitors. This article reviews the progress in oral delivery of these proteins, provides comments on the strategies to improve their oral bioavailability, and highlights their current market trends.     

Genetic and nongenetic factors influencing substance use by adolescents

Substance use by adolescents can lead to mortality, physical and social morbidity, and a brain disorder called substance dependence if allowed to progress to chronic, repetitive self-administration. Substance abuse and dependence can begin in adolescence or adulthood, but many of the attitudes and behaviors that affect risk become established during adolescence. Genetic risk factors have been identified for at least two distinct disorders and more are under active study to determine the cause and pathophysiology of addictive disorders. Although much remains to be done, a complex interplay of numerous genetic and environmental risk factors clearly is involved. An understanding of the most important environmental risk factors has led to effective primary prevention approaches; knowledge of the genetic risk factors and neuropharmacology of drugs of abuse in the brain is beginning to influence secondary prevention efforts and treatment, including better medications for addictive disorders. A large proportion of adolescents carry a genetic vulnerability that can be expressed when they accept peer and societal influences that promote experimentation with substances of abuse. At that point, the genetic factors take over, maintaining the drug self-administration pattern. Decay of social status results from association with drug-using peers and shifts in priorities supportive of drug use rather than education and productivity. More research into the genetic risk factors and applications of current knowledge to treatment is needed.     

Short report: Crimean-Congo hemorrhagic fever outbreak in Rawalpindi, Pakistan, February 2002

A nosocomial outbreak of Crimean-Congo hemorrhagic fever occurred in Rawalpindi, Pakistan in February 2002. The identified index case died shortly after admission to a hospital. Two of the health care workers became secondary cases; one of them died on day 13 after coming in contact with the index case. The other secondary case was successfully treated with oral ribavirin.     

Comparison of efficacy and immunogenicity of original versus current botulinum toxin in cervical dystonia

The authors compared 130 patients treated for cervical dystonia with original botulinum toxin (BTX) type A (Botox; Allergan, Inc., Irvine, CA), 42 of whom were exposed only to the original BTX type A used before 1998 (25 ng protein/100 units), and 119 treated only with the current BTX type A (5 ng of protein/100 units). Blocking antibodies were detected in 4 of 42 (9.5%) patients treated only with original BTX type A but in none of the 119 patients treated exclusively with current BTX type A (p < 0.004). The current preparation decreased the risk of antibody formation by a factor of six. The authors conclude that the low risk of antibody formation after current BTX type A treatment is related to lower protein load.     

Voltage-gated Ca2+ channel Ca(V)1.3 subunit expressed in the hair cell epithelium of the sacculus of the trout Oncorhynchus mykiss: cloning and comparison across vertebrate classes

Full-length sequence (>6.5 kb) has been determined for the Ca(V)1.3 pore-forming subunit of the voltage-gated Ca(2+) channel from the saccular hair cells of the rainbow trout (Oncorhynchus mykiss). Primary structure was obtained from overlapping PCR and cloned fragments, amplified by primers based on teleost, avian, and mammalian sources. Trout saccular Ca(V)1.3 was localized to hair cells, as evidenced by its isolation from an epithelial layer in which the hair cell is the only intact cell type. The predicted amino acid sequence of the trout hair cell Ca(V)1.3 is approximately 70% identical to the sequences of avian and mammalian Ca(V)1.3 subunits and shows L-type characteristics. The trout hair cell Ca(V)1.3 expresses a 26-aa insert in the I-II cytoplasmic loop (exon 9a) and a 10-aa insert in the IVS2-IVS3 cytoplasmic loop (exon 30a), neither of which is appreciably represented in trout brain. The exon 9a insert also occurs in hair cell organs of chick and rat, and appears as an exon in human genomic Ca(V)1.3 sequence (but not in the Ca(V)1.3 coding sequence expressed in human brain or pancreas). The exon 30a insert, although expressed in hair cells of chick as well as trout, does not appear in comparable rat or human tissues. Further, the IIIS2 region shows a splice choice (exon 22a) that is associated with the hair cell organs of trout, chick, and rat, but is not found in human genomic sequence. The elucidation of the primary structure of the voltage-gated Ca(2+) channel Ca(V)1.3 subunit from hair cells of the teleost, representing the lowest of the vertebrate classes, suggests a generality of sensory mechanism for Ca(V)1.3 across hair cell systems. In particular, the exon 9a insert of this channel appears to be the molecular feature most consistently associated with hair cells from fish to mammal, consonant with the hypothesis that the latter region may be a signature for the hair cell.     

Sexual life style, drug habit and socio-demographic status of drug addicts in Bangladesh

The sexual life style, drug habit and socio-demographic status of 253 male hospitalized drug addicts were investigated. This study was conducted during the period June 1997 to July 1998, and each case was selected by the random sampling method. The research instrument was an interviewer-administered questionnaire, the sexual habits, number and quality of sex partners, use of condoms, sexually transmitted diseases, etc., were considered as indicators of the sexual life style of the drug addicts. Eighty-eight percent (n=233) of the addicts were heterosexual. Bisexuality was found only in 7% (n=18) of the addicts. Eighty-seven percent (n=240) of the addicts have multiple sex partners of either commercial or residential category. Most of the drug addicts (72%,n=181) did not use condoms. Fifty-seven percent (n=145) of the addicts were observed to have sexual diseases. As indicators of a drug habit, starting drug, choice of drug, period of addiction, sharing of needles, etc., were included. Cannabis was the starting substance for 59% (n=149) of the addicts. Heroin was the drug of choice for 60% (n=157) addicts. A single drug was taken only by 8% (n=20) of the addicts and the remaining 92% (n=233) took multiple drugs. The drug addicts (n=97) who used mostly injection (87%,n=84) shared needles. Education, occupation, income, age, marital status, influencing factors for addiction were considered as socio-demographic characteristics. Young adults (79%,n=199), secondary educated (46%,n=116), low-mid income (60%,n=150), businessmen (46%,n=150) and married (60%,n=151) people were found highly involved in addiction. Self-curiosity and a friend's incitement were revealed as the most important influencing factors for taking drugs.     

Comparison and outcome of commissurotomy by metallic valvotome and balloon commissurotomy

The purpose of this study was to compare the echocardiographic outcome of percutaneous transvenous metallic mitral commissurotomy (PMMC) and Percutaneous transvenous balloon mitral commissurotomy (PTMC). This prospective comparative study was carried out during the period of January 1999 to June 2000 in the department of Cardiology, National Institute of cardiovascular diseases (NICVD) and national heart foundation hospital, Dhaka Bangladesh. Two dimension, M-mode, spectral and colour Doppler studies were done to all patient of mitral stenosis both before and after PMMC and PTMC. The increased in mitral valve area in PMMC was statistically significant than PTMC. (P<0.047).