Prognostic Value of Depth of Invasion in Squamous Cell Carcinoma of the Oral Cavity of Size 4 cm or Less

PURPOSE/OBJECTIVE(S)

We aimed to evaluate the role of the depth of invasion (DOI) as an independent prognostic factor in the absence of other adverse features in squamous cell carcinoma (SqCC) of the oral cavity with a size of 4 cm or less.

MATERIALS/METHODS

We performed a retrospective analysis in a multi-institutional cohort of patients with oral cavity SqCC, size of 4 cm or less. We included those who were treated with upfront surgery with negative resection margins from 2010 to 2021 and those with one or no nodal metastasis. Those who were treated with postoperative radiotherapy were excluded. The DOI and other adverse features, such as close resection margins, lymphovascular invasion, perineural invasion, and nodal metastasis, were evaluated in univariate and multivariate analyses for their association with locoregional recurrence (LRR).

RESULTS

A total of 155 patients were included with a median follow-up of 23.7 months. 56 patients (36.1%) had DOI greater than 5 mm. 26 patients (16.8%) experienced LRR and one experienced distant metastasis. Multivariate analysis showed that DOI was the only prognostic factor associated with a higher rate of LRF (p = 0.004). The 2-year LRF rates of those with DOI ≤ 5 mm and DOI > 5mm were 4.7% and 30.3%, respectively.

CONCLUSION

This study implies that DOI greater than 5 mm may be an independent prognostic factor of the SqCC of the OCC and may be indicated for adjuvant radiotherapy.

Choosing Wisely between Radiotherapy Dose-Fractionation Schedules: The Molecular Graded Prognostic Assessment (molGPA) for Elderly Glioblastoma (eGBM-molGPA)

PURPOSE/OBJECTIVE(S)

This study aimed to develop a graded prognostic assessment (GPA) model integrating genomic characteristics in patients with elderly glioblastoma (eGBM), and compare the efficacy between conventionally fractionated radiotherapy (CFRT) vs. hypofractionated radiotherapy (HFRT) in each risk group.

MATERIALS/METHODS

Patients aged ≥65 years who underwent surgical resection followed by radiotherapy (RT) with or without temozolomide (TMZ) for newly diagnosed IDH-wildtype eGBM between 2006 and 2021 were included in this multicenter cohort study. Patients who were planned for a ≥6-week or ≤4-week radiotherapy were regarded as being treated with CFRT or HFRT, respectively. Based on the prognostic factors significantly identified through multivariate analysis for overall survival (OS), we developed the molecular GPA for eGBM (eGBM-molGPA) and assigned 0.0, 0.5, and 1.0 points in proportion to the corresponding hazard ratio (HR) of each factor. Then, the survival outcomes by treatment groups were evaluated according to the eGBM-molGPA scores.

RESULTS

A total of 334 and 239 patients who underwent CFRT and HFRT were included, respectively, and 86% of patients were treated with TMZ-based chemoradiation. With a median follow-up of 17.4 months for survivors, the median OS was 18.7 months for CFRT plus TMZ group, 15.1 months for HFRT plus TMZ group, and 10.4 months for RT alone group, respectively (all p<0.001). In the multivariate analysis, Karnofsky performance scale, surgical extent, TMZ, and the methylation status of the MGMT promoter were identified as strong prognostic factors for OS, with an estimated HR of greater than 1.5 (all p<0.001). Additionally, subventricular zone involvement, temporalis muscle thickness, RT regimen, and the mutation status of TERT promoter and TP53 gene were found to be significant prognostic factors for OS, with an estimated HR of less than 1.5. The eGBM-molGPA was established based on these prognostic factors (Table 1) and patients were allocated to three risk groups, which included high risk (total score of 3.0-4.5), intermediate risk (1.5-2.5), and low risk (0.0-1.0). Patients treated with CFRT plus TMZ had significantly improved OS compared to those treated with HFRT plus TMZ or RT alone in the low and intermediate risk groups (p<0.001). However, in the high-risk group, there was no significant difference in OS between treatment options (p = 0.770).

CONCLUSION

CFRT plus TMZ can be a more effective strategy for selected eGBM patients compared to HFRT. For high-risk patients, a protracted treatment schedule might not be beneficial. The novel eGBM-molGPA can be used as a clinical tool for choosing wisely among treatment options. Further prospective studies are warranted to establish optimal RT guidelines for eGBM patients.

Complexity of the genetic basis of ageing in nature revealed by a clinal study of lifespan and methuselah, a gene for ageing, in Drosophila from eastern Australia

Clinal studies are a powerful tool for understanding the genetic basis of climatic adaptation. However, while clines in quantitative traits and genetic polymorphisms have been observed within and across continents, few studies have attempted to demonstrate direct links between them. The gene methuselah in Drosophila has been shown to have a major effect on stress response and longevity phenotypes based largely on laboratory studies of induced mutations in the mth gene. Clinal patterns in the most common mth haplotype and for lifespan (both increasing with latitude) have been observed in North American populations of D. melanogaster, implicating climatic selection. While these clinal patterns have led some to suggest that mth influences ageing in natural populations, limited evidence on the association between the two has so far been collected. Here, we describe a significant cline in the mth haplotype in eastern Australian D. melanogaster populations that parallel the cline in North America. We also describe a cline in mth gene expression. These findings further support the idea that mth is itself under selection. In contrast, we show that lifespan has a strong nonlinear clinal pattern, increasing southwards from the tropics, but then decreasing again from mid-latitudes. Furthermore, in association studies, we find no evidence for a direct link between mth haplotype and lifespan. Thus, while our data support a role for mth variation being under natural selection, we found no link to naturally occurring variation in lifespan and ageing in Australian populations of D. melanogaster. Our results indicate that the mth locus likely has genetic background and environment-specific effects.

Polymorphism in the couch potato gene clines in eastern Australia but is not associated with ovarian dormancy in Drosophila melanogaster

Natural selection can generate parallel latitudinal clines in traits and gene frequencies across continents, but these have rarely been linked. An amino acid (isoleucine to lysine, or I462K) polymorphism of the couch potato (cpo) gene in Drosophila melanogaster is thought to control female reproductive diapause cline in North America (Schmidt et al. 2008, Proc Natl Acad Sci USA, 105, 16207-16211). Here, we show that under standard diapause-inducing conditions (12 °C and short photoperiod) (Saunders et al. 1989, Proc Natl Acad Sci USA, 86, 3748-3752), egg maturation in Australian flies is delayed, but not arrested at previtellogenic stages. At 12 °C, the phenotypic distribution in egg development was bimodal at stages 8 and 14 and showed a strong nonlinear pattern on the east coast of Australia, with incidence of egg maturation delay (ovarian dormancy) increasing both toward tropical and temperate climates. Furthermore, we found no evidence for an association between the cpo I462K polymorphism and ovarian dormancy at either 12 or 10 °C (when egg maturation was often delayed at stage 7). Owing to strong linkage disequilibrium, the latitudinal cline in cpo allele frequencies was no longer evident once variation in the In(3R)P inversion polymorphism was taken into account. Our results suggest that the standard diapause-inducing conditions (12 °C and short photoperiod) were not sufficient to cause the typical previtellogenic developmental arrest in Australian flies and that the cpo I462K polymorphism does not explain the observed delay in egg development. In conclusion, ovarian dormancy does not show a simple latitudinal cline, and the lack of cpo-dormancy association suggests a different genetic basis to reproductive dormancy in North America and Australia.

Molecular basis of adaptive shift in body size in Drosophila melanogaster: functional and sequence analyses of the Dca gene

Latitudinal body size clines in animals conforming to Bergmann's rule occur on many continents but isolating their underlying genetic basis remains a challenge. In Drosophila melanogaster, the gene Dca accounts for approximately 5-10% of the natural wing size variation (McKechnie SW, Blacket MJ, Song SV, Rako L, Carroll X, Johnson TK, Jensen LT, Lee SF, Wee CW, Hoffmann AA. 2010. A clinally varying promoter polymorphism associated with adaptive variation in wing size in Drosophila. Mol Ecol. 19:775-784). We present here functional evidence that Dca is a negative regulator of wing size. A significant negative latitudinal cline of Dca gene expression was detected in synchronized third instar larvae. In addition, we clarified the evolutionary history of the three most common Dca promoter alleles (Dca237-1, Dca237-2, and Dca247) and showed that the insertion allele (Dca247), whose frequency increases with latitude, is associated with larger wing centroid size and higher average cell number in male flies. Finally, we showed that the overall linkage disequilibrium (LD) was low in the Dca promoter and that the insertion/deletion polymorphism that defines the Dca alleles was in strong LD with two other upstream sites. Our results provide strong support that Dca is a candidate for climatic adaptation in D. melanogaster.

Tools for high-spatial and temporal-resolution analysis of environmental responses in plants

Understanding how plants cope with environmental change requires a spatiotemporal perspective. In this review, we highlight recent work which has led to the development and use of novel tools for the high spatial and temporal-resolution analysis of the plant-environment interaction. FACS-based transcriptome and immunoprecipitation-based translatome data sets have provided an important foundation for the analysis of the transcriptional and translational control of environmental responses in each tissue layer of the plant. Complementary approaches, based on a proteomic toolkit, have provided insight into the biological response of Arabidopsis to NaCl and the relationship between transcript and protein levels. The development and adaptation of biosensors and ion-specific dyes provides the capacity to visualize changes in the transport and accumulation of metabolites and small molecules such as sugars, Na(+) and Ca(2+) at the cellular level. Finally, live-imaging approaches coupled with automated image-analysis algorithms are revealing new levels of dynamism and plasticity in the response to light and gravity. Together, these tools will provide a more comprehensive understanding of environmental responses in plants, which will aide in the development of new crop varieties for sustainable agriculture.

A clinally varying promoter polymorphism associated with adaptive variation in wing size in Drosophila

Body size often shows adaptive clines in many ectotherms across altitude and latitude, but little is known about the genetic basis of these adaptive clines. Here we identify a polymorphism in the Dca (Drosophila cold acclimation) gene in Drosophila melanogaster that influences wing size, affects wing:thorax allometry and also controls a substantial proportion of the clinal wing-size variation. A polymorphism in the promoter region of Dca had two common alleles showing strong reciprocal clinal variation in frequency with latitude along the east coast of Australia. The Dca-237 allele increased towards the tropics where wing size is smaller. A within-population association study highlighted that an increase in the frequency of this allele decreased wing size but did not influence thorax size. A manipulated increase in the level of expression of Dca achieved through UAS-GAL4 was associated with a decrease in wing size but had no effect on thorax size. This was consistent with higher Dca expression levels in family lines with higher frequency of the Dca-237 allele. Genetic variation in the promoter region of the Dca gene appears to influence adaptive size variation in the eastern Australian cline of Drosophila melanogaster and accounts for more than 10% of the genetic variation in size within and between populations.

Selection for cold resistance alters gene transcript levels in Drosophila melanogaster

Microarrays have been used to examine changes in gene expression underlying responses to selection for increased stress resistance in Drosophila melanogaster, but changes in expression patterns associated with increased resistance to cold stress have not been previously reported. Here we describe such changes in basal expression levels in replicate lines following selection for increased resistance to chill coma stress. We found significant up- or down-regulation of expression in 94 genes on the Affymetrix Genome 2.0 array. Quantitative RT-PCR was used to confirm changes in expression of six genes. Some of the identified genes had previously been associated with stress resistance but no previously identified candidate genes for cold resistance showed altered patterns of expression. Seven differentially expressed genes that form a tight chromosomal cluster and an unlinked gene AnnX may be potentially important for cold adaptation in natural populations. Artificial selection for chill coma resistance therefore altered basal patterns of gene expression, but we failed to link these changes to plastic changes in expression under cold stress or to previously identified candidate genes for components of cold resistance.

Identification of candidate genes for fenvalerate resistance in Helicoverpa armigera using cDNA-AFLP

A cDNA-amplified fragment length polymorphisms approach was undertaken to screen for candidate genes associated with fenvalerate resistance in the AN02 strain of Helicoverpa armigera. Larvae and adults of this strain manifest approximately 50-fold resistance, which is suppressible by piperonyl butoxide and controlled by the semidominant gene RFen1 previously mapped to AFLP Linkage Group 13. Two cytochrome P450s (CYP337B1 and CYP4S1), one carboxylesterase-like protein and one glutathione transferase were found to be constitutively upregulated in resistant insects. Mapping of these potential detoxification genes showed that one of them, the novel P450 CYP337B1, was tightly linked to the resistance locus. This suggests that the RFen1(R) allele has a cis-acting effect on CYP337B1 expression, and possible trans-acting effects on expression of other genes.