Primary renal hypoplasia in humans and mice with PAX2 mutations: evidence of increased apoptosis in fetal kidneys of Pax2(1Neu) +/- mutant mice

PAX2 mutations cause renal-coloboma syndrome (RCS), a rare multi-system developmental abnormality involving optic nerve colobomas and renal abnormalities. End-stage renal failure is common in RCS, but the mechanism by which PAX2 mutations lead to renal failure is unknown. PAX2 is a member of a family of developmental genes containing a highly conserved 'paired box' DNA-binding domain, and encodes a transcription factor expressed primarily during fetal development in the central nervous system, eye, ear and urogenital tract. Presently, the role of PAX2 during kidney development is poorly understood. To gain insight into the cause of renal abnormalities in patients with PAX2 mutations, kidney anomalies were analyzed in patients with RCS, including a large Brazilian kindred in whom a new PAX2 mutation was identified. In a total of 29 patients, renal hypoplasia was the most common congenital renal abnormality. To determine the direct effects of PAX2 mutations on kidney development fetal kidneys of mice carrying a Pax2 (1Neu)mutation were examined. At E15, heterozygous mutant kidneys were approximately 60% of the size of wild-type littermates, and the number of nephrons was strikingly reduced. Heterozygous 1Neu mice showed increased apoptotic cell death during fetal kidney development, but the increased apoptosis was not associated with random stochastic inactivation of Pax2 expression in mutant kidneys; Pax2 was shown to be biallelically expressed during kidney development. These findings support the notion that heterozygous mutations of PAX2 are associated with increased apoptosis and reduced branching of the ureteric bud, due to reduced PAX2 dosage during a critical window in kidney development.

Large cell neuroendocrine carcinoma of the uterine cervix: a report of a case with coexisting cervical intraepithelial neoplasia and human papillomavirus 16

Large cell neuroendocrine carcinomas (LCNECs), one of the four newly categorised endocrine tumors of the uterine cervix, are unusual and aggressive tumors. The present report describes a case of LCNEC diagnosed at an early stage and associated with cervical intraepithelial neoplasia (CIN). The LCNEC showed organoid and trabecular growth patterns and was positive for chromogranin and synaptophysin. The CIN lesion was of a high grade and was negative for these neuroendocrine markers. Polymerase chain reaction (PCR) using genomic DNA extracted from archival tissue demonstrated human papillomavirus (HPV) type 16 DNA in both the LCNEC and CIN lesions. These histological, immunohistochemical and PCR findings suggested that the LCNEC lesion was distinct from the CIN lesion and that both resulted from the carcinogenic field effect of HPV 16.

p53 mutations and human papillomavirus DNA in oral squamous cell carcinoma: correlation with apoptosis

Forty-two oral squamous cell carcinomas (SCCs) were analysed for p53 mutations and human papillomavirus (HPV) infection to examine the prevalency of these factors and correlation with apoptotic index (AI; number of apoptotic cells per 100 tumour cells) of the tumour tissue. In polymerase chain reaction (PCR)-Southern blot analysis, HPV DNAs were detected from 22 out of 42 SCCs (52%) with predominance of HPV-16 (68%). p53 mutations in exons 5-8, screened by nested PCR-single-strand conformation polymorphism (PCR-SSCP) analysis, were observed in 16 of 42 tumours (38%). The state of the p53 gene did not show any correlation with HPV infection. The terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labelling (TUNEL) method was used for detection of apoptotic cells. The mean AI was 2.35, ranging from 0.31 to 6.63. SCCs associated with p53 mutation had significantly lower AI than those without p53 mutation (P < 0.01), whereas no difference in AI was found between SCCs with and without HPV infection. The results of this study confirmed that HPV infection and/or p53 mutations are implicated, but are not mutually exclusive events, in carcinogenesis of oral SCC and also showed that decrease in apoptosis is more closely related to p53 mutation than HPV infection.