Identification of the fifth subunit of Saccharomyces cerevisiae replication factor C.

Yeast replication factor C (RF-C) is a multipolypeptide complex required for chromosomal DNA replication. Previously this complex was known to consist of at least four subunits. We here report the identification of a fifth RF-C subunit from Saccharomyces cerevisiae, encoded by the RFC5 (YBR0810) gene. This subunit exhibits highest homology to the 38 kDa subunit (38%) of human RF-C (activator 1). Like the other four RFC genes, the RFC5 gene is essential for yeast viability, indicating an essential function for each subunit. RFC5 mRNA is expressed at steady-state levels throughout the mitotic cell cycle. Upon overexpression in Escherichia coli Rfc5p has an apparent molecular mass of 41 kDa. Overproduction of RF-C activity in yeast is dependent on overexpression of the RFC5 gene together with overexpression of the RFC1-4 genes, indicating that the RFC5 gene product forms an integral subunit of this replication factor.

Clinical staging versus laparotomy and combined modality with MOPP versus ABVD in early-stage Hodgkin's disease: the H6 twin randomized trials from the European Organization for Research and Treatment of Cancer Lymphoma Cooperative Group.

PURPOSE: To compare (1) clinical staging and irradiation alone versus staging laparotomy and treatment adaptation in patients with a favorable prognosis (H6F); (2) two combined modalities in patients with an unfavorable prognosis (H6U). PATIENTS AND METHODS: The H6F trial (n = 262) consisted of randomization to clinical staging plus subtotal nodal irradiation (STNI) or to staging laparotomy plus treatment adaptation (adjuvant chemotherapy [CT] only in the 33% with negative laparotomy). The H6U trial (n = 316) consisted of no laparotomy, randomization to mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) or doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD), and mantle irradiation. RESULTS: In the H6F trial, 6-year freedom from progression (FFP) rates (78% v 83%; P = .27) were similar in clinical and laparotomy stagings, respectively. Survival rates were 93% and 89%, due to laparotomy-related deaths. In the H6U trial, the ABVD arm had superior results (6-year FFP rate, 88% v 76%; P = .01), but they were not significant for survival (91% v 85%; P = .22). CT discontinuation due to hematologic intolerance occurred more often with MOPP (14.5% v 7.3%). Decrease of the pulmonary vital capacity ([VC] < 70% of the theoretic value) was observed more frequently after ABVD than after MOPP (12% v 2%; P = .08), with two lethal pulmonary insufficiencies occurring in the ABVD arm. No modification of the isotopic left ventricular ejection fraction (LVEF) occurred. Gonadal toxicity was less in the ABVD arm. CONCLUSION: Early-stage patients benefit from treatment adaptation to initial characteristics in terms of tumor control and late toxicities. Staging laparotomy before STNI may be deleted even in favorable patients at no cost to survival or FFP. In unfavorable patients, ABVD achieved better results than MOPP, at lower hematologic and gonadal cost. Therefore, despite its pulmonary toxicity, ABVD is the best choice to design improved CT regimens associated with mantle irradiation.