Lymphatic drainage of sinonasal malignancies and the role of sentinel node biopsies

BACKGROUND

Locoregional recurrence is a critical factor in the prognosis of sinonasal malignancies. Due to the rarity of these tumours, as well as the heterogeneity of histologies and anatomical subsites, there is little evidence regarding the rate and location of regional metastases in sinonasal malignancies. Elective regional lymph node dissection in the therapy of sinonasal malignancies has become controversial. On the one hand, elective regional lymph node dissection is considered to be an overtreatment in the cN0 cases. On the other hand, undetected occult lymphatic metastases are associated with a poor prognosis. In this study, we discuss the role of sentinel lymph node biopsy as a minimally invasive procedure in the treatment of sinonasal malignancies based on our two years of practical experience and the currently available data.

RESULTS

This is a descriptive, monocentric, retrospective study, including 20 cases of cN0 malignant sinonasal neoplasm, that underwent a surgical therapy between 2020 and 2022. The following aspects were investigated: tumour entity, localisation of the primary tumour, tumoral stage, localisation of the sentinel lymph nodes, and postoperative complications. Squamous cell carcinoma was the most frequently diagnosed tumour entity (50%), followed by adenocarcinoma (20%) and malignant melanoma (15%), adenoid cystic carcinoma and mucoepidermoid carcinoma. Sentinel lymph nodes were most frequently found in the ipsilateral neck region I (45%), followed by the ipsilateral neck region II (40%). In all cases, the removed lymph nodes were free of malignancy. There were no postoperative complications due to lymph node biopsy. There were no recurrences during the study period.

CONCLUSION

Sentinel node biopsy could add more safety to the management of cN0 sinonasal malignancies due to its low morbidity. Whether SNB could provide an alternative to elective neck dissection in the management of SNM should be investigated in further studies.

Blebs promote cell survival by assembling oncogenic signalling hubs

Most human cells require anchorage for survival. Cell-substrate adhesion activates diverse signalling pathways, without which cells undergo anoikis-a form of programmed cell death1. Acquisition of anoikis resistance is a pivotal step in cancer disease progression, as metastasizing cells often lose firm attachment to surrounding tissue2,3. In these poorly attached states, cells adopt rounded morphologies and form small hemispherical plasma membrane protrusions called blebs4-11. Bleb function has been thoroughly investigated in the context of amoeboid migration, but it has been examined far less in other scenarios12. Here we show by three-dimensional imaging and manipulation of cell morphological states that blebbing triggers the formation of plasma membrane-proximal signalling hubs that confer anoikis resistance. Specifically, in melanoma cells, blebbing generates plasma membrane contours that recruit curvature-sensing septin proteins as scaffolds for constitutively active mutant NRAS and effectors. These signalling hubs activate ERK and PI3K-well-established promoters of pro-survival pathways. Inhibition of blebs or septins has little effect on the survival of well-adhered cells, but in detached cells it causes NRAS mislocalization, reduced MAPK and PI3K activity, and ultimately, death. This unveils a morphological requirement for mutant NRAS to operate as an effective oncoprotein. Furthermore, whereas some BRAF-mutated melanoma cells do not rely on this survival pathway in a basal state, inhibition of BRAF and MEK strongly sensitizes them to both bleb and septin inhibition. Moreover, fibroblasts engineered to sustain blebbing acquire the same anoikis resistance as cancer cells even without harbouring oncogenic mutations. Thus, blebs are potent signalling organelles capable of integrating myriad cellular information flows into concerted cellular responses, in this case granting robust anoikis resistance.

Classification of endonasal HHT lesions using digital microscopy

BACKGROUND

Recurrent spontaneous epistaxis is the most common clinical manifestation and the most debilitating symptom in hereditary haemorrhagic telangiectasia (HHT) patients. To this date, there exist only a classification of HHT patients by different genetic mutations. There is no standard classification for the mucocutaneous endonasal manifestations of HHT. The aim of the present study was to document the variety of endonasal HHT lesions using digital microscopy and to propose a clinical classification.

METHODS

We recorded the endonasal HHT lesions of 28 patients using a digital microscope. We reconstructed the 3D images und videos recorded by digital microscope afterwards and classified the endonasal lesions of HHT in two classes: Grade A, presence of only flat telangiectasias in the mucosa level and Grade B, (additional) presence of raised berry or wart-like telangiectasia spots. We investigated also Haemoglobin level by routine laboratory procedures, plasma VEGF level by ELISA, Severity of epistaxis by epistaxis severity score (ESS) and quality of life by a linear visual analogue scale (VAS).

RESULTS

We found a higher quality of life and a lower severity of epistaxis in Grade A patients in comparison to Grade B patients. No difference in plasma VEGF level and in Haemoglobin between Grad A patients and Grade B patients could be detected. Plasma VEGF levels showed no gender specific differences. It could also not be correlated to the extranasal manifestation.

CONCLUSION

The classification for endonasal manifestation of HHT proposed in this study indicates severity of epistaxis und quality of life. Digital microscopy with the ability of 3D reconstruction of images presents a useful tool for such classifications. The classification of endonasal HHT lesions using digital microscopy allows to evaluate the dynamic of HHT lesions in the course of time independent of examiner. This allows also to evaluate the efficacy of the different treatment modalities by dynamic of HHT lesions. Moreover digital microscopy is very beneficial in academic teaching of rare diseases.

Modification of x-ray-induced killing of HeLa S3 cells by inhibitors of DNA synthesis

After irradiation of HeLa S3 cells with 220 kv x-rays during G1, treatment with any of six inhibitors of DNA synthesis results in the progressive enhancement of cell killing (loss of colony-forming ability). Incubation with hydroxyurea, cytosine arabinoside, or hydroxylamine reduces survival five- to twentyfold in about 8 hr, following an x-ray dose of 400 rads. In contrast, treatment with 5-fluorodeoxyuridine, deoxyadenosine, or thymidine after this same dose reduces survival less than twofold during a comparable time interval. These differences occur at drug concentrations which reduce the rate of DNA synthesis by at least 95% (except in the case of hydroxylamine, which inhibits DNA synthesis to a smaller extent), but which kill no unirradiated cells during the treatment periods. When inhibition of DNA synthesis with either hydroxyurea or cytosine arabinoside is reversed by addition of appropriate precursors of DNA, the enhancement is abolished. With hydroxyurea, the rate of cell killing is dependent on the dose of x-rays previously administered, and the extent of enhancement seems to be related to the drug concentration. Imposition of a delay between irradiation and addition of hydroxyurea does not abolish the enhancement effect, but instead causes a proportional lag in its inception. Postirradiation treatment of S phase cells with either hydroxyurea or cytosine arabinoside also enhances killing. Furthermore, unlike early G1 cells, S cells (and, as shown previously, cells blocked at the G1-S transition) are sensitized by preirradiation exposure to hydroxyurea.

Recombination between Sindbis virus RNAs

The Sindbis virus RNA genome is divided into two modules--one coding for the nonstructural protein genes and the other coding for the structural protein genes. In our studies of recombination, the two parental RNAs were defective in different modules. Analysis of the recombinant RNAs demonstrated that the parental RNAs each contributed its intact module and that the crossovers occurred within the defective modules. The recombinational events giving rise to infectious virion RNAs could create deletions, rearrangements or insertions as long as they occurred outside of the functional module. These crossovers produced RNA genomes that contained two functional subgenomic RNA promoters.

Recombination between Sindbis virus RNAs

The genome (49S RNA) of Sindbis virus is a positive-strand RNA of 11.7 kb that consists of two domains. The 5' two-thirds of the RNA codes for the proteins required for replication and transcription of the RNA. The 3' one-third codes for the structural proteins. The latter are translated from a 26S subgenomic RNA identical in sequence to the 3' one-third of the genome. The 26S RNA is transcribed by initiation from an internal promoter that spans the junction between the nonstructural and structural genes. We have used Sindbis virus RNAs transcribed from cloned cDNAs to demonstrate recombination between Sindbis virus RNAs in cultured cells. Several different combinations of deleted or mutationally altered RNAs gave rise to infectious recombinants. In 7 of 10 different crosses, the infectious recombinant RNAs were larger than wild-type 49S RNA. We sequenced the recombinant RNAs in the region spanning the junction between the nonstructural and structural protein genes from five different crosses. In three of the crosses, this is the only region within which recombination could have taken place to produce an infectious 49S RNA. Recombination also occurred in this region in the other two crosses. The recombinant RNAs were distinct from wild-type RNA and from each other. All contained sequence insertions derived from the parental RNAs. One contained a deletion and a rearrangement, and one also contained a stretch of 11 nucleotides not found in the Sindbis virus genome. When each of the parental RNAs contained a functional subgenomic RNA promoter, both promoters were present and functional in the recombinant RNA. Those recombinants with large sequence insertions showed evidence of evolution toward the wild-type single-junction RNA.

Effects of 5'-terminal modifications on the biological activity of defective interfering RNAs of Sindbis virus

We have been studying defective interfering (DI) genomes of the RNA enveloped virus Sindbis virus. Deletion mapping of a DI cDNA demonstrated that only sequences at the 3' and 5' termini of the genome are required for the DI RNA to be biologically active. We constructed a series of cDNAs that transcribe DI RNAs differing only in 5'-terminal sequences. Two of the 5' termini identical to ones found in naturally occurring DI RNAs are the 5' terminus of the virion RNA (DI-549) and the first 142 nucleotides from the 5' terminus of the subgenomic 26S mRNA attached to the 5' terminus of the virion RNA (DI-15). The latter has a 42-nucleotide deletion from nucleotides 25 to 66 in the 26S RNA sequence. These DI RNA transcripts were biologically active, but one (DI-526) which did not have the 42-nucleotide deletion of DI-15 was not replicated. The DI RNA isolated after the presumed amplification of the DI-526 transcript had deleted the first 54 nucleotides of the 26S RNA sequences. The 5' terminus of Sindbis virion RNA contains a stem and loop region that is conserved among alphaviruses. An 11-nucleotide deletion in DI-549 that disrupted this stem and loop rendered this DI RNA inactive. In contrast, this same deletion in DI-15 and one that removed an additional 100 nucleotides of the virion 5' terminus did not prevent its amplification. We did not detect by computer analysis any common secondary structures among the biologically active DI RNAs that distinguished them from those RNAs that were not amplified. Our results support the conclusion that tertiary structure or the ability of the RNA to adapt its structure upon interaction with protein is important in the recognition process.

Deletion mapping of Sindbis virus DI RNAs derived from cDNAs defines the sequences essential for replication and packaging

Defective-interfering (DI) genomes of a virus contain sequence information essential for their replication and packaging. They need not contain any coding information and therefore are a valuable tool for identifying cis-acting, regulatory sequences in a viral genome. To identify these sequences in a DI genome of Sindbis virus, we cloned a cDNA copy of a complete DI genome directly downstream of the promoter for the SP6 bacteriophage DNA dependent RNA polymerase. The cDNA was transcribed into RNA, which was transfected into chicken embryo fibroblasts in the presence of helper Sindbis virus. After one to two passages the DI RNA became the major viral RNA species in infected cells. Data from a series of deletions covering the entire DI genome show that only sequences in the 162 nucleotide region at the 5' terminus and in the 19 nucleotide region at the 3' terminus are specifically required for replication and packaging of these genomes.

Suprathreshold auditory adaptation in normal and pathologic ears

The Wood delayed loudness balance method was studied in normal and pathologic ears to determine the characteristics of suprathreshold auditory adaptation in three groups of subjects. No consistent relationship could be established between the amount and direction of the loudness change with the frequency, sound pressure level, or sensation level of the adapting signal. Suprathreshold adaptation, as measured by the Wood method, does not provide sufficient diagnostic information to be useful in a clinical setting.