Proton and Carbon Ion Radiotherapy for Operable Early-Stage Lung Cancer: 3-Year Results of a Prospective Nationwide Registry

PURPOSE/OBJECTIVE(S)

The purpose of this analysis was to report subset analysis as to progression-free survival (PFS) and overall survival (OS) of particle-beam radiation therapy for operable early-stage lung cancer.

MATERIALS/METHODS

Patients of early-stage lung cancer (T1-T2aN0) who were eligible for radical surgery but did not wish to undergo surgery were treated by proton-ion (PT) or carbon-ion (CT) radiation therapy and enrolled in Japanese prospective registry. In this analysis, PFS and OS by clinical stage, tumor location, pathological confirmation and particle-ion type were evaluated.

RESULTS

A total of 274 patients were enrolled and included in efficacy and safety analyses. Most tumors were adenocarcinoma (44%), and 105 (38%) were not histologically confirmed and diagnosed clinically. 250 (91%) of 274 patients had tumors that were peripherally situated. 138 (50%) and 136 (50%) patients were treated by PT and CT, respectively. The median follow-up time for all censored patients was 42.8 months (IQR 36.7 - 49.0). No grade 3 or severe treatment-related toxicity was observed. 3-year PFS was 81% (95% CI;76-86) and OS was 93% (95% CI;89-96), respectively. As to particle-ion type, 3-year PFS were 79.0% and 81.9% in PT and CT (p = 0.19), and 3-year OS were 93.9% and 91.1% in PT and CT (P = 0.72), respectively. For PFS, pathological confirmation, clinical stage was significant factors but there were no significant differences by tumor location or particle-ion type; for OS, clinical stage was significant factor but there was no significant difference on pathological confirmation, tumor location or particle-ion type (Table1). Table 1. 3-year PFS and OS CONCLUSION: Particle therapy for operable early-stage lung cancer resulted in excellent 3-year OS and PFS on each subset.

Unsedated transnasal ultrathin esophagogastroduodenoscopy may provide better diagnostic performance in gastroesophageal reflux disease

Transnasal ultrathin esophagogastroduodenoscopy (N-EGD) with less gagging reflexes under non-sedation is likely suitable for the diagnosis of gastroesophageal reflux disease (GERD), however, N-EGD might have drawbacks, including its low image resolution. Limited information is available regarding the diagnosability of N-EGD for GERD. We compared the utility and gagging reflexes of three different endoscopies, including N-EGD, ultrathin transoral EGD (UTO-EGD) and conventional oral EGD (CO-EGD), in the diagnosis of GERD. We performed screening endoscopy in 1580 patients (N-EGD n=727, UTO-EGD n=599, CO-EGD n=254) and compared the frequency distributions of the severity of reflux esophagitis, hiatus hernia, and Barrett's epithelium to estimate the diagnostic performance of each endoscopy. We also analyzed patients' tolerability of endoscopy by the subjective evaluation of gagging reflexes. In the diagnosis of reflux esophagitis and Barrett's epithelium, there was no significant difference in the frequency distributions of the severity of the diseases among three EGDs. However, the incidence of Barrett's epithelium was higher than that in the previous nationwide survey of GERD in Japan. The evaluated size of hiatus hernia was smaller in N-EGD than in two other peroral endoscopies. The size of hiatus hernia correlated significantly with severity of gagging reflexes that was also lowest when diagnosed with N-EGD. N-EGD had an equivalent performance in the diagnosis of reflux esophagitis and Barrett's epithelium compared with CO-EGD. Enlargement of hiatus hernia induced by gagging reflexes was minimal in N-EGD, resulting in its better performance in the diagnosis of Barrett's epithelium.

Bir1/Cut17 moving from chromosome to spindle upon the loss of cohesion is required for condensation, spindle elongation and repair

BACKGROUND

In mammals, proteins containing BIR domains (IAPs and survivin) are implicated in inhibiting apoptosis and sister chromatid separation. In the nematode, Bir1 is required for a proper localization of aurora kinase, which moves from the mitotic chromosome in metaphase to the spindle midzone in anaphase as a passenger. Fission yeast Bir1/Pbh1 is essential for normal mitosis.

RESULTS

A temperature sensitive mutant cut17-275 exhibits the defect in condensation and spindle elongation at 36 degrees C, while securin is degraded. Gene cloning shows that the cut17+ gene is identical to bir1+/pbh1+. At 26 degrees C, cut17-275 is UV sensitive as the repair of DNA damage is severely compromised. Bir1/Cut17 is a nuclear protein in interphase, which is then required for recruiting condensin to the mitotic nucleus, and concentrates to form a discrete number of dots from prometaphase to metaphase. Once the chromatids are separated, Bir1/Cut17 no longer binds to kinetochores and instead moves to the middle of spindle. Chromatin immunoprecipitation suggested that Bir1/Cut17 associates with the outer repetitious centromere region in metaphase. Following the initiation of anaphase the protein switches from being a chromosomal protein to a spindle protein. This transit is stringently regulated by the state of sister chromatid cohesion proteins Mis4 and Rad21. Ark1, is an aurora kinase homologue whose mitotic distribution is identical to, and under the control of Bir1/Cut17.

CONCLUSIONS

Bir1/Cut17 and Ark1 act as "passengers" but they may play a main role as a recruitment factor, essential for condensation, spindle elongation and DNA repair. Bir1/Cut17 should have roles both in mitotic and in interphase chromosome. The proper location of Ark1 requires Bir1/Cut17, and the mitotic localization of Bir1/Cut17 requires sister cohesion.

Fission yeast living mitosis visualized by GFP-tagged gene products

The fission yeast Schizosaccharomyces pombe has been used as a model organism to study cell cycle control and dynamic chromosome behavior during anaphase segregation as genetic and cytological approaches are easily amenable. To understand the role of gene products involved in these cellular events, it is important to determine intracellular localization of each gene product during the cell cycle. In this article, visualization in living cells of several gene products involved in cell cycle control and sister chromatid separation is described. The genes tagged with jellyfish green fluorescent protein (GFP) include sad1(+) (encoding a spindle pole body (SPB) protein), atb2(+) (alpha-tubulin), mis6(+) (a kinetochore protein), eat1(+) (a novel actin-like protein localized in the nucleus) and cdc13(+) (a mitotic cyclin). In addition, LacI which is bound to a DNA segment containing LacO repeat sequences integrated near the centromere (cen1) is visualized. These are useful to monitor cell cycle events in living cells.

Cut8, essential for anaphase, controls localization of 26S proteasome, facilitating destruction of cyclin and Cut2

BACKGROUND

Anaphase-promoting complex (APC)/cyclosome and 26S proteasome are respectively required for polyubiquitination and degradation of mitotic cyclin and anaphase inhibitor Cut2 (Pds1/securin). In fission yeast, mutant cells defective in cyclosome and proteasome fail to complete mitosis and have hypercondensed chromosomes and a short spindle. A similar phenotype is seen in a temperature-sensitive strain cut8-563 at 36 degrees C, but the molecular basis for Cut8 function is little understood.

RESULTS

At high temperature, the level of Cut8 greatly increases and it becomes essential to the progression of anaphase. In cut8 mutants, chromosome mis-segregation and aberrant spindle dynamics occur, but cytokinesis takes place with normal timing, leading to the cut phenotype. This is due to the fact that destruction of mitotic cyclin and Cut2 in the nucleus is dramatically delayed, though polyubiquitination of Cdc13 occurs in cut8 mutant. Cut8 is localized chiefly to the nucleus and nuclear periphery, a distribution highly similar to that of 26S proteasome. In cut8 mutant, however, 26S proteasome becomes mostly cytoplasmic, showing that Cut8 is needed for its proper localization.

CONCLUSION

Cut8 is a novel evolutionarily conserved heat-inducible regulator. It facilitates anaphase-promoting proteolysis by recruiting 26S proteasome to a functionally efficient nuclear location.

Control of metaphase-anaphase progression by proteolysis: cyclosome function regulated by the protein kinase A pathway, ubiquitination and localization

Ubiquitin-mediated proteolysis is fundamental to cell cycle progression. In the fission yeast Schizosaccharomyces pombe, a mitotic cyclin (Cdc13), a key cell cycle regulator, is degraded for exiting mitosis, while Cut2 has to be destroyed for the onset of sister chromatid separation in anaphase. Ubiquitination of these proteins requires the special destruction box (DB) sequences locating in their N-termini and the large, 20S complex called the anaphase-promoting complex or cyclosome. Here we show that cyclosome function during metaphase-anaphase progression is regulated by the protein kinase A (PKA) inactivation pathway, ubiquitination of the cyclosome subunit, and cellular localization of the target substrates. Evidence is provided that the cyclosome plays pleiotropic roles in the cell cycle: mutations in the subunit genes show a common anaphase defect, but subunit-specific phenotypes such as in G1/S or G2/M transition, septation and cytokinesis, stress response and heavy metal sensitivity, are additionally produced, suggesting that different subunits take distinct parts of complex cyclosome functions. Inactivation of PKA is important for the activation of the cyclosome for promoting anaphase, perhaps through dephosphorylation of the subunits such as Cut9 (Apc6). Cut4 (Apc1), the largest subunit, plays an essential role in the assembly and functional regulation of the cyclosome in response to cell cycle arrest and stresses. Cut4 is highly modified, probably by ubiquitination, when it is not assembled into the 20S cyclosome. Sds23 is implicated in DB-mediated ubiquitination possibly through regulating de-ubiquitination, while Cut8 is necessary for efficient proteolysis of Cdc13 and Cut2 coupled with cytokinesis. Unexpectedly, the timing of proteolysis is dependent on cellular localization of the substrate. Cdc13 enriched along the spindle disappears first, followed by decay of the nuclear signal, whereas Cut2 in the nucleus disappears first, followed by decline in the spindle signal during metaphase-anaphase progression.