Intermittent hepatic arterial infusion of high-dose 5FU on a weekly schedule for liver metastases from colorectal cancer

PURPOSE

We performed phase I and II studies to examine the usefulness of intermittent hepatic arterial infusion of high-dose 5-fluorouracid (5-FU) for patients with liver metastasis from colorectal cancer.

METHODS

As the phase I study, 1000, 1250 and 1500 mg/m2 of 5-FU were administered over 5 h by hepatic arterial infusion on a weekly schedule to establish the recommended dose. Based on the results of the phase I study, the phase II study was performed to confirm the efficacy of the recommended dose thus obtained.

RESULTS

In the phase I study, the dose-limiting factors of this therapy were gastrointestinal and central nervous system toxicities, and the recommended dose was judged to be 1000 mg/m2. In the phase II study, 1000 mg/m2 of 5-FU was administered over 5 h once a week on an outpatient basis, and this therapy was repeated as long as possible. The response rate was 78% (25/32), with an overall median survival time of 25.8 months (without extrahepatic lesions 25.9 months; with extrahepatic lesions 17.3 months).

CONCLUSIONS

(1) Compared with conventional continuous infusion, the advantages of this therapy were that it caused no decrease in the patient's quality of life as a result of being permanently equipped with a pump and it thus enabled more cost-effective use of the pump, (2) The phase II study on 32 patients showed that this therapy caused no serious toxicities, with a response rate of 78% and a survival time of 25.8 months, which exceeded the results with conventional continuous infusion. If the reproducibility of these results is established in further studies involving multicenter collaboration, this therapy will be able to become the standard local chemotherapy for liver metastases from colorectal cancer. (3) Important problems remaining to be solved are improvement of the technical aspects and studies of combined use with systemic chemotherapy. Furthermore, to finally determine the position of this therapy in the treatment system for liver metastasis from colorectal cancer, it is necessary to conduct comparative trials versus systemic chemotherapy, using the survival time as the end-point.

Preventive effects of polysaccharides extracted from human tubercle bacilli (specific substance of Maruyama) on colonic carcinogenesis in rats

Polysaccharides extracted from human tubercle bacilli (specific substance of Maruyama [SSM]) have been clinically applied with satisfactory results. Thymidylate synthetase (TS) and thymidine kinase (TK) are key enzymes in de novo and salvage pathways for pyrimidine nucleotide synthesis. Well- and moderately well differentiated adenocarcinomas induced with 1,2-dimethylhydrazine (DMH) are widely distributed throughout the colorectal tract with high TK activity, and the poorly differentiated type is mainly restricted in the proximal colon and the cecum with high TS activity in rats. Subcutaneously injecting the rats with SSM reduced TS activity in colonic nontumorous regions, but in the tumorous regions it reduced TK activity compared with that of the DMH-treated rats without SSM treatment. SSM is suggested to reduce the colorectal carcinogenesis induced with DMH by inhibiting DNA synthesis in a de novo pathway, and to suppress the development of the tumors by decreasing DNA synthesis in the salvage pathway in rats.

Antianginal effects of YM430, a novel calcium entry-blocking and beta-adrenoceptor-blocking agent in several experimental angina models

1. We evaluated the antianginal effects of YM430 in several experimental models in vitro and in vivo. 2. In isolated dog coronary artery, YM430 (10(-8)-10(-6) M) inhibited 3,4-diaminopyridine-induced rhythmic contractions with an IC50 value of 59.2 nM. 3. In anesthetized rats, YM430 (10-100 mg/kg PO) inhibited arginine vasopressin-induced ST-segment depression with an IC50 value of 36.6 mg/kg PO. 4. In anesthetized dogs, YM430 (0.3 mg/kg IV) significantly inhibited ST-segment elevation induced by coronary artery occlusion. 5. These findings suggest that YM430 may be of value in the treatment of various types of angina pectoris such as variant and stable angina.

[Cardiac surgery in patients with chronic renal failure on maintenance dialysis]

From July 1988 through August 1996, 54 patients with chronic renal failure (CRF) on maintenance dialysis (50 hemodialysis = HD, and 4 continuous ambulatory peritoneal dialysis) have undergone some sort of surgical procedure requiring the use of extra corporeal circulation (ECC); 42 patients underwent isolated coronary artery bypass grafting (CABG), 8 valve replacement, 3 combined procedures and 1 correction of a congenital heart defect. The protocol called for maintenance dialysis on the day before surgery, large volume hemofiltration (HF) during the ECC period, postoperative K+ management with dextrose-insulin if required, and resumption of whatever preoperative maintenance dialysis 24 hours after the operative procedure. The mean diafiltrate volume of HF was 7963 +/- 2688 ml which was replaced with 6342 +/- 2748 ml. No patient required emergency HD before the resumption of the maintenance dialysis, although in 40% of the early patients HD was added on the second postoperative day. However as experience was gained, in the latter 60% of patients resumption of maintenance dialysis (HD 3 times a week) was thought to be sufficient. The incidence of calcification in patients with CRF is higher not only of involved coronary artery segments (4.5 +/- 2.3 segments; AHA coronary classification) than its counterpart without CRF, but also of the ascending aorta which mandated modifications of the technique in 6 patients (operation under ventricular fibrillation, cannulation access other than ascending aorta). The use of arterial in situ conduits for CABG was also thought to be advantageous, and the left internal thoracic artery combined to the gastro-epiploic artery was used in 11 patients (26.2%). Four patients died) (7.4%): 2 from arrhythmia, one from intestinal necrosis and one from multiple cerebral infarction. Thus we conclude that the outlined protocol is quite effective in controlling fluid and electrolyte balance in patients on maintenance dialysis allowing to undertake surgical procedures requiring the use of extra corporeal circulation relatively safely.

Reliability and validity of the Japanese version of the Zarit Caregiver Burden interview

Despite a rapid increase in disabled elderly in Japan, the burden of the caregiver has not been properly assessed due to a lack of objective measurements. Our study was aimed at adapting and validating the Zarit Caregiver Burden Interview (ZBI) in Japan, which is one of the most widely used measurements for caregivers' burden in the United States. Sixty-six caregivers answered the self-administered questionnaire, involving the Japanese version of the ZBI and questions regarding their caregiving situation. Our study demonstrated that the Japanese version of the ZBI had equally as high reliability and validity as the original version. The Japanese ZBI had a high test-retest reliability (r = 0.76) and internal consistency (Cronbach's alpha = 0.93). The total score of the ZBI was highly correlated with the caregivers' score of the Center for Epidemiologic Studies Depression Scale (CES-D) score (r = 0.50), as well as a single global rating of burden (r = 0.71). It was also shown that demographic distribution of the score of the Japanese version had a similar trend to that of the original version. Caregivers who looked after patients with behavioral disturbances were found to have a significantly higher ZBI score than those who looked after patients without behavioral disturbances, which is consistent with previous findings. It is concluded that the Japanese version of the ZBI can be used to measure feelings of burden of caregivers in the Japanese population and can be used for cross-cultural comparison.

Bone mass loss due to estrogen deficiency is compensated in transgenic mice overexpressing human osteoblast stimulating factor-1

Osteoblast stimulating factor-1 (OSF-1) stimulates in vitro proliferation and differentiation of osteoblastic cells, and its gene is expressed in the bone and brain tissues in mammals and amphibians. To evaluate the in vivo function of OSF-1 in bone metabolism, transgenic mice overexpressing the human osf-1 gene driven by the osteocalcin promoter were generated. Femoral bone mineral content was increased in transgenic mice relative to wild-type controls as estimated by ash assay, depending on the transgene copy number per cell. In ovariectomized mice, bone mass loss due to estrogen deficiency was observed in both transgenic and control mice but bone mass was still higher in transgenic mice than in controls. Bone mass in ovariectomized transgenic mice was comparable to that in wild-type mice without ovariectomy. These observations indicate that OSF-1 may direct in vivo appositional bone formation by increasing osteoblast activity rather than decreasing osteoclast activity, suggesting a new way to treat osteoporosis with OSF-1.

Nerve-sparing retroperitoneal lymph node dissection for metastatic testicular cancer

BACKGROUND

Nerve-sparing techniques are used during retroperitoneal lymph node dissection (RPLND) in patients with early stage testicular cancer to preserve postoperative ejaculatory function. Indications for the procedures have been extended to patients with a postchemotherapy retroperitoneal residual mass without compromising the efficacy of surgery. We report 6 cases diagnosed with metastatic testicular cancer who underwent nerve-sparing RPLND.

METHODS

Between January 1994 and March 1996, 6 patients with metastatic testicular cancer underwent nerve-sparing RPLND. Five of these patients received primary chemotherapy and a retroperitoneal residual mass. Four patients underwent complete bilateral RPLND and 2 underwent unilateral template surgery.

RESULTS

After a mean follow-up of 18.7 months (range, 8 to 34), there have been no local recurrences and 5 (83%) patients report antegrade ejaculation.

CONCLUSION

Nerve-sparing RPLND is applicable for selected patients with metastatic testicular cancer without increasing the risk of local recurrence. Ejaculatory function is preserved in the majority of patients, contributing to the improvement of the quality of life in men who require such surgery.

The case fatality rate of methicillin-resistant Staphylococcus aureus (MRSA) infection among the elderly in a geriatric hospital and their risk factors

From April 1991 to March 1993, there were 49 elderly patients with methicillin-resistant Staphylococcus aureus (MRSA) infection in a geriatric hospital in Fukuoka, Japan. The retrospective study was carried out in order to evaluate the various factors which may influence the case fatality rate of MRSA infection among the elderly. Among them, 33 patients (67.3%) died while only 16 patients became culture-negative for MRSA and discharged after recovering from MRSA infection. A univariate analysis revealed that male sex (odds ratio [OR] = 12.25, 95% confidence interval [CI] = 2.80-53.55), hypoalbuminemia (OR = 3.83, 95% CI = 1.11-13.21) and an excessive usage of antibiotics (OR = 6.67, 95% CI = 1.70-26.09) were risk factors for death among the patients with MRSA infection. In a multivariate analysis, male sex and an excessive usage of antibiotics were still risk factors while hypoalbuminemia was not. However, hypoalbuminemina was more common in male patients than female patients (78.3% vs. 42.3%, p < 0.05). These findings suggest that the case fatality rate of MRSA infection may be high and also suggest that the elderly with MRSA infection who had hypoalbuminemia and/or received many antibiotics may have a poor prognosis.

Prospective evaluation of prostate specific antigen density and systematic biopsy for detecting prostate cancer in Japanese patients with normal rectal examinations and intermediate prostate specific antigen levels

PURPOSE

To improve the specificity of cancer detection in patients with normal digital rectal examination and intermediate prostate specific antigen (PSA) level, PSA density has been recommended, with biopsy based on a PSA density of 0.15 or more. PSA density is reportedly higher in Japanese men than in white men, because of physiological differences between the 2 races. We prospectively evaluated PSA density as a discriminator of prostate cancer in Japanese men.

MATERIALS AND METHODS

We evaluated prospectively 60 consecutive men with normal digital rectal examinations and serum PSA levels of 4.1 to 10.0 ng./ml. enrolled during a 17-month period. All patients underwent transrectal ultrasound guided sextant biopsies, regardless of calculated PSA density and transrectal ultrasound findings. Serum PSA levels were determined by IMx assay.

RESULTS

Overall, 8 of 60 men (13%) had prostate cancer. There was no significant difference in mean PSA between those with positive and those with negative biopsies, but the difference was significant in the mean PSA density (mean 0.24 and 0.15, respectively, p < 0.01). Receiver operating characteristics curves for PSA and PSA density demonstrated superior benefit for PSA density in this patient population. A reference PSA density value of 0.19 was chosen because it showed the highest sum of sensitivity and specificity, which gave a sensitivity of 75%, a specificity of 87%, a positive predictive value of 46% and a negative predictive value of 96%.

CONCLUSIONS

The results suggest that PSA density improves the specificity of cancer detection in men with a normal digital rectal examination and an intermediate PSA level. Although further study with a larger patient population is needed to obtain a best-fit value, an optimal PSA density cutoff seems to be higher than that recommended in the literature from western countries. Because of possible racial differences in serum PSA and prostate volume, the role of PSA density in Asian men should be studied independently.

Developmental immunohistochemistry of growth inhibitory factor in normal brains and brains of patients with Down syndrome

Growth inhibitory factor, a new metallothioneinlike protein, was investigated at postmortem examination in the brains of 18 patients with Down syndrome ranging in age from 18 weeks gestation to 50 years of age and in 20 age-matched normal controls by developmental immunohistochemistry. In the frontal cortex of both Down syndrome patients and controls, growth inhibitory factor immunoreactivity was localized in the cell bodies and processes of protoplasmic astrocytes from 18 weeks gestation, and these immunoreactive processes formed so dense a meshwork in the gray matter that they outlined neuronal perikarya as negative contours in the brain at age more than 16 years. The number of growth inhibitory factor-immunoreactive astrocytes exhibited a greater increase in layer 3 than in layer 2 in controls from 37 weeks gestation to 7 months of age, although there was no difference in the growth inhibitory factor-positive cell number between layers 2 and 3 in young Down syndrome patients. Therefore, growth inhibitory factor in astrocytes may be correlated with dendritic maturation of neurons. On the other hand, growth inhibitory factor-immunoreactive astrocytes in layer 2, where senile plaques are abundant, were smaller than those in layer 3 in adult Down syndrome patients from age 32 years. When senile plaques began to immunoreact with the amyloid precursor protein, the number of growth inhibitory factor-immunoreactive astrocytes decreased around senile plaques in elderly Down syndrome brains with the Alzheimer type of dementia. On the contrary, the number of glial fibrillary acidic protein-immunoreactive astrocytes around senile plaques increased. This loss of growth inhibitory factor around senile plaques may be correlated with neuronal loss or degeneration and lead to sprouting responses which may be involved in the formation of senile plaques.

[A case of scrotal cancer with inguinal lymph node metastasis treated by multidisciplinary modalities including chemotherapy with methotrexate, bleomycin and cisplatin]

We report a case of scrotum with inguinal lymph node metastasis which was successfully treated by multidisciplinary modalities including combination chemotherapy and radiotherapy. A 60-year-old man was admitted with ulcerative induration of the scrotum and inguinal lymph node swelling. Biopsy of the scrotal skin showed squamous cell carcinoma. He received 4 courses of combination chemotherapy with methotrexate, bleomycin and cisplatin. The primary lesion disappeared macroscopically and metastatic lymphadenopathy showed 50% reduction in size. Both lesions were further treated with radiotherapy (60 Gy). Because the primary lesion became ulcerative 7 months after irradiation, partial resection of the scrotum was performed. He has been free of recurrence 22 months after chemotherapy.

Adenovirus vector-mediated gene transduction to chondrocytes: in vitro evaluation of therapeutic efficacy of transforming growth factor-beta 1 and heat shock protein 70 gene transduction

OBJECTIVE

To investigate the effects of adenovirus vector-mediated gene transduction of E. coli beta-galactosidase (LacZ), transforming growth factor-beta 1 (TGF-beta 1), and heat shock protein 70 (HSP 70) on human chondrocyte-like cell line (HCS-2/8).

METHODS

We examined expression of transduced genes and their expression periods by 5 bromo-4-chloroindolyl-beta-D-galactoside (X-gal) staining. Northern blotting, ELISA, and Western blotting. To assess the influence of TGF-beta 1 and HSP70 gene transduction, the expression of mRNA of type II collagen, proteoglycan core protein, matrix metalloproteinase 3 (MMP3) and tissue inhibitor of matrix metalloproteinase 1 were examined by Northern blotting.

RESULTS

Staining with X-gal indicated that the genes were transduced into a majority of the cells. Expression of the transduced genes in the cells was continued for at least 21 days. Transduction of TGF-beta 1 gene enhanced mRNA expression of type II collagen and proteoglycan core protein, but suppressed MMP3 mRNA expression in the cells. Expression of HSP70 was also high. Enhanced expression of HSP70 elevated mRNA expression of proteoglycan core protein.

CONCLUSION

These results indicate adenovirus vector is useful in chondrocyte gene therapy, and it could be an efficient mediator of TGF-beta 1 and HSP70 gene transduction.

Methicillin-resistant Staphylococcus aureus (MRSA) isolation from pharyngeal swab cultures of Japanese elderly at admission to a geriatric hospital

The isolation rate of the methicillin-resistant Staphylococcus aureus(MRSA) from pharyngeal swab cultures in Japanese elderly was studied at admission to a geriatric hospital. The subjects were 233 consecutive patients admitted to Kitakyushu Tsuyazaki Hospital from April 1994 to March 1996. The isolation rate of MRSA was 3.0% in the patients admitted from their own homes, 9.7% in those transferred from nursing homes and 14.0% in those transferred from other hospitals. The patients from their own homes were younger than those from nursing homes, the latter being older than those transferring from other hospitals. The patients from their own homes had better activities of daily living(ADL), higher levels of hemoglobin and serum albumin than those from nursing homes or other hospitals. The white blood cell counts, and the proportion of patients with positive c-reactive protein or with fever did not differ among the three groups. Multiple logistic regression analysis revealed that fever and ADL disability were independent risk factors for the isolation of MRSA, and hypoalbuminemia was a risk factor for MRSA isolation in the model using serum albumin instead of ADL score. These results suggest that the lower isolation rate MRSA among patients from their own homes may be partly due to better ADL and nutritional status compared with those from nursing homes or other hospitals.

[Urethral recurrence of bladder cancer 16 years after total cystectomy. A case report]

A 74-year-old man was admitted to our hospital. Diagnosis of invasive bladder cancer was made and a total cystectomy was performed on January, 30, 1980. Histological examination showed transitional cell carcinoma, grade 2, pT1 is N0M0. After 16 years, when he suffered left femur, he had right inguinal lymphnode swelling. On the biopsy of the inguinal mass, histology was transitional cell carcinoma. The urethral washing cytology was positive. Lung CT scan dem onstrated multiple lesions. He was diagnosed of the urethral recurrence, right inguinal lymphnode metastasis and lung metastasis of bladder cancer. This case is the 5th case of urethral recurrence of bladder cancer following cystectomy in our hospital.

Smoking behaviour and personality: a population-based study in Japan

AIMS

The aim of our study was to determine whether the previously reported findings also apply to a general population in Japan and whether, among current smokers, such personality characteristics can be correlated with the age they started to smoke and their present daily consumption of cigarettes.

DESIGN

Cross-sectional survey.

SETTING

Miyagi prefecture, in northern Japan.

PARTICIPANTS

20,538 residents in Miyagi, aged 40-64 years.

MEASUREMENT

A self-administered questionnaire involving smoking status (current, ex- and non-smokers) and patterns and the Japanese version of the short-form Eysenck Personality Questionnaire-Revised (EPQ-R).

FINDINGS

(1) Current and ex-smokers were higher on Extraversion and Psychoticism than non-smokers for both genders. (2) Heavy smokers were higher on Psychoticism than light smokers and those who started to smoke prior to the legally permitted age were higher on Psychoticism than those who did not.

CONCLUSIONS

(1) Our study confirmed that the findings which had been previously reported in selected samples in western countries also apply to a general population in Japan; (2) current smokers were found to be heterogeneous in terms of Psychoticism when the age they started to smoke and their present daily consumption of cigarettes were taken into account.

Inversion of chromosome 11 inv(11)(p15q22), as a recurring chromosomal aberration associated with de novo and secondary myeloid malignancies: identification of a P1 clone spanning the 11q22 breakpoint

We studied four patients with inv(11)(p15q22) associated with malignant myeloid diseases by using fluorescence in situ hybridization (FISH) with phage and cosmid probes mapped and ordered on 11q22-24. Two of the four patients had non-Hodgkin's lymphoma or acute lymphoblastic leukemia as the primary malignancy and had received cytotoxic chemotherapy, including topoisomerase II inhibitors. The other two had de novo acute myeloid leukemia or myelodysplastic syndrome. FISH analysis showed that all 11q breakpoints were located centromeric to the MLL gene and between cosmids CN2900 and CN1323. We identified a yeast artificial chromosome (YAC) clone that spanned the inv(11) breakpoints on 11q. From this YAC, we identified a P1 clone, which included the breakpoints in at least three of the four patients. It is highly likely that the same gene on the P1 clone is rearranged in leukemic cells of each patient. This gene may be one of the targets for topoisomerase II inhibitors.

A negative regulatory region of the murine Hox11 gene

The HOX11 gene was isolated from the chromosomal breakpoint of human T cell acute lymphoblastic leukemias with a chromosomal translocation t(10;14). Expression of this proto-oncogene is strictly controlled in normal tissues. However, regulatory elements of the gene have never been studied. Since the HOX11 gene is well conserved between human and murine, we sequenced 5' flanking region of the murine Hox11 gene and analyzed the elements. We identified the transcription start site (+1) of the gene using mRNA from fetal spleens by primer extension analysis. The start site was determined at 795 bp upstream from the ATG site. A typical TATA box sequence was found at 35 bp upstream from the start site. Furthermore, promoter activity of the 5' flanking region of the start site was monitored by luciferase assay. The activity mainly located within a 540-bp fragment immediately upstream from the start site (-540 to +1). The (-1240 to -540) region contained a negative regulatory element of the transcription. The TATA box sequence and the nucleotide sequence around the transcription start site were conserved in the human HOX11 gene. The transcription start site of the human HOX11 gene in normal tissues is discussed.

[Enhancement pattern of hepatic metastases from colorectal cancer on CT arteriography]

The enhancement pattern of hepatic metastases from colorectal cancer on CT arteriography (CTA) was evaluated in 79 cases with 405 lesions. Sixty-two percent of overall lesions irrespective of size showed ring-like enhancement, and 33% of lesions less than 1 cm in diameter showed homogeneous enhancement. In pathological examination of 59 resected lesions, the enhancement pattern on CTA had a good correlation with the extent of tumor cellularity, necrosis or fibrosis in the lesions. And in 8.5% of resected lesions, the extent of enhancement on CTA was larger than that of perfusion defect on CT arterial portography, which was almost equal to the size in the resected specimen. In such lesions, the enhancement on CTA might include enhancement of normal hepatic parenchyma around the lesion.

[Treatment of prostate cancer by radiotherapy]

Fifty-seven patients with clinically localized prostate cancer were treated by radical prostatectomy or external radiation therapy following pelvic lymphadenectomy. Comparing the outcome of radiotherapy with that of prostatectomy in 42 T2 patients without lymph node metastasis, the 5-year cause-specific survival did not differ between the radical prostatectomy group (n = 31) and radiotherapy group (n = 11). The 5-year disease-free survival of the prostatectomy group, however, was superior to that of radiotherapy group (p = 0.01). To cure patients with T2 prostate cancer, therefore, it is supposed that radical prostatectomy should be performed. To improve the treatment outcome after radiotherapy, stereotactic radiosurgery for prostate cancer has been attempted in our institution. Phantom experiments using a linear accelerator demonstrated a round dose distribution, and high reproducibility of prostate positioning was confirmed by CT when a thermoplastic immobilization device was used to fix the pelvis. In one patient with localized prostate cancer treated by radiosurgery, acute complication has not been recognized during the 5 week follow-up. Radiosurgery may be available to treat clinically localized prostate cancer.

Developmental and aging changes in the expression of amyloid precursor protein in Down syndrome brains

We studied immunohistochemically the expression of beta-amyloid precursor protein (APP) in the frontal lobes of 18 Down syndrome (DS) patients (20 gestation weeks (GW) to 50 years) and 15 controls (17 GW to 50 years) using six purified antibodies against the secretory forms (N-terminal, N-Amy and Amy540), the Kunitz-type protease inhibitor (KPI) domain, residues 1-28 of beta protein (Affi28), and the carboxyl-terminal fragment (Ac) of APP. In the cortex of fetuses, neonates and infants, immunoreactivity for N-Amy and Ac was observed in both neurons and glial cells, and that for Affi28 in glial cells in the subpial layer in both DS patients and controls suggesting the functioning role of APP was a growth factor. This immunoreactivity disappeared in childhood and reappeared in adulthood in only DS patients. The earlier reappearance of those in DS patients from a young adult age than in normal controls may result from a gene dosage effect, since APP is encoded on chromosome 21. The N-Amy, Amy540, Affi28 and Ac immunoreactivity in glial cells in the developing white matter in the both DS patients and controls may be associated with myelination glia. Immunoreactivity for KPI was noted on the tunica media of the arteries from the neonatal period to adulthood in only DS patients. In senile plaques in DS patients, N-terminal and Affi28 immunoreactivity became detectable at the age of 32 years. N-terminal immunoreactivity in the senile plaques was noted along the periphery of the senile plaques, while that for Affi28 was around the amyloid core. Thus, each fragment of APP exhibited a different localization and time course of immunohistochemical expression. The results indicated that APP plays a role in neuronal development and that its earlier reappearance in adult DS patients is associated with the regeneration process related to aging.

The inv(11)(p15q22) chromosome translocation of de novo and therapy-related myeloid malignancies results in fusion of the nucleoporin gene, NUP98, with the putative RNA helicase gene, DDX10

The inv(11)(p15q22) is a recurrent chromosomal abnormality associated with de novo and therapy-related myeloid malignancies. Here we report the molecular definition of this chromosomal aberration in four patients. Positional cloning showed the consistent rearrangement of the DDX10 gene on chromosome 11q22, which encodes a putative RNA helicase. The translocation targets the NUP98 gene on 11p15, a member of the FG peptide repeat nucleoporin family. In DDX10 and NUP98, the inv(11) breakpoints occurred within two introns of each gene and the two genes merged in-frame to produce the chimeric transcripts characteristic of this translocation. Although two reciprocal chimeric products, NUP98-DDX10 and DDX10-NUP98, were predicted, only NUP98-DDX10 appears to be implicated in tumorigenesis. DDX10 is predicted to be involved in ribosome assembly. NUP98 has been identified as a nuclear pore complex protein and a target of chromosomal translocation in acute myeloid leukemia through the t(7;11)(p15;p15) translocation. The predicted NUP98-DDX10 fusion protein may promote leukemogenesis through aberrant nucleoplasmic transport of mRNA or alterations in ribosome assembly.