Inactivating negative regulators of cortical branched actin enhances persistence of single cell migration

The Rac1-WAVE-Arp2/3 pathway pushes the plasma membrane by polymerizing branched actin, thereby powering membrane protrusions that mediate cell migration. Here, using knockdown (KD) or knockout (KO), we combine the inactivation of the Arp2/3 inhibitory protein arpin, the Arp2/3 subunit ARPC1A and the WAVE complex subunit CYFIP2, all of which enhance the polymerization of cortical branched actin. Inactivation of the three negative regulators of cortical branched actin increases migration persistence of human breast MCF10A cells and of endodermal cells in the zebrafish embryo, significantly more than any single or double inactivation. In the triple KO cells, but not in triple KD cells, the 'super-migrator' phenotype was associated with a heterogenous downregulation of vimentin (VIM) expression and a lack of coordination in collective behaviors, such as wound healing and acinus morphogenesis. Re-expression of vimentin in triple KO cells largely restored normal persistence of single cell migration, suggesting that vimentin downregulation contributes to the maintenance of the super-migrator phenotype in triple KO cells. Constant excessive production of branched actin at the cell cortex thus commits cells into a motile state through changes in gene expression.

Germline HPF1 retrogene insertion in RB1 gene involved in cancer predisposition

About half of the human genome is composed of repeated sequences derived from mobile elements, mainly retrotransposons, generally without pathogenic effect. Familial forms of retinoblastoma are caused by germline pathogenic variants in RB1 gene. Here, we describe a family with retinoblastoma affecting a father and his son. No pathogenic variant was identified after DNA analysis of RB1 gene coding sequence and exon-intron junctions. However, RB1 mRNA analysis showed a chimeric transcript with insertion of 114 nucleotides from HPF1 gene inside RB1 gene. This chimeric transcript led to an insertion of 38 amino acids in functional domain of retinoblastoma protein. Subsequent DNA analysis in RB1 intron 17 revealed the presence of a full-length HPF1 retrogene insertion in opposite orientation. Functional assay shows that this insertion has a deleterious impact on retinoblastoma protein function. This is the first report of a full-length retrogene insertion involved in human Mendelian disease leading to a chimeric transcript and a non-functional chimeric protein. Some retrogene insertions may be missed by standard diagnostic genetic testing, so contribution of retrogene insertions to human disease may be underestimated. The increasing use of whole genome sequencing in diagnostic settings will help to get a more comprehensive view of retrogenes.

Homologous recombination deficiency derived from whole-genome sequencing predicts platinum response in triple-negative breast cancers

The high frequency of homologous recombination deficiency (HRD) is the main rationale of testing platinum-based chemotherapy in triple-negative breast cancer (TNBC), however, the existing methods to identify HRD are controversial and there is a medical need for predictive biomarkers. We assess the in vivo response to platinum agents in 55 patient-derived xenografts (PDX) of TNBC to identify determinants of response. The HRD status, determined from whole genome sequencing, is highly predictive of platinum response. BRCA1 promoter methylation is not associated with response, in part due to residual BRCA1 gene expression and homologous recombination proficiency in different tumours showing mono-allelic methylation. Finally, in 2 cisplatin sensitive tumours we identify mutations in XRCC3 and ORC1 genes that are functionally validated in vitro. In conclusion, our results demonstrate that the genomic HRD is predictive of platinum response in a large cohort of TNBC PDX and identify alterations in XRCC3 and ORC1 genes driving cisplatin response.

Abstract 3363: Spatial and longitudinal tumor heterogeneity in head and neck squamous cell carcinoma patients treated with primary surgery

Introduction: Cell-free tumor DNA (ctDNA) is an emerging biomarker in head and neck squamous cell carcinoma (HNSCC) for disease staging, patients’ recurrence risk stratification and early detection of relapse. We aimed to compare variants identified in ctDNA versus surgical tumor specimen, and to study the evolution of the mutational landscape of ctDNA over time in HNSCC.

Patients and Method: Forty-one HNSCC patients treated with curative-intent primary surgery from SCANDARE cohort (NCT03017573) were evaluated for longitudinal ctDNA-based NGS. Overall, 28 patients were treated with adjuvant (chemo)radiotherapy, and 31 experienced recurrence. Formalin-fixed paraffin-embedded tumor tissues at surgery were available for 41 patients. Serial contributive ctDNA were retrieved from all 41 patients at the date of surgery, 36 patients within 19 weeks after surgery, 20 patients at six months after surgery, and 22 patients at recurrence. Tissue DNA was personalized detected with a custom NGS panel of 571 genes (DRAGON) and ctDNA was sequenced using another personalized dedicated NGS panel including up to 15 genes (OncoFOLLOW).

Results: Most frequently mutated genes in tissue included TP53 (15.9%), FAT1 (6.7%), NOTCH1 (5.5%) and PIK3CA (4.3%) with similar allelic ratio to ctDNA at baseline surgery. Higher prevalence of KRAS and TP53 mutations was found in ctDNA at recurrence in comparison with ctDNA and tissue, respectively, at baseline surgery (KRAS: 6.3% versus 1.6% and 0.6%; TP53: 31.2% versus 21.1% and 15.9%). Additional variants in NRAS, HRAS, TP53, JAK2 and SDHA were detected in 6 patients in ctDNA at surgery and were not found in tissue, suggesting spatial intratumor heterogeneity. Twenty-three/36 patients (64%) had detected ctDNA within 19 weeks after surgery among whom, 17/23 patients (74%) had disease recurrence. Eleven/20 patients (including 10 with adjuvant treatment) had detected ctDNA at six months after surgery among whom 6 patients (55%) had disease recurrence. Fifteen/22 patients (68%) had detected ctDNA at recurrence. Emerging pathogenic variants were found in patients with detected ctDNA after surgery (n=7/23; 30%), at six months after surgery (n=1/11; 9%) and at recurrence (n=4/15; 27%).

Conclusion: Our study suggests spatial and longitudinal tumor heterogeneity and reports emerging mutations in ctDNA over time in HNSCC. Prognostic significance characterization of the ctDNA dominant clone allele frequency is ongoing.

Citation Format: Grégoire Marret, Constance Lamy, Sophie Vacher, Mathieu Séné, Ladidi Ahmanache, Laura Courtois, Zakhia El Beiano, Jerzy Klijanienko, Charlotte Martinat, Nicolas Servant, Choumouss Kamoun, Linda Larbi Chérif, Thierry Bronzini, Cédric Balsat, Jean-François Laes, Aubray Prévot, Sébastien Sauvage, Maxime Lienard, Emmanuel Martin, Bérengère Genin, Nathalie Badois, Maria Lesnik, Antoine Dubray-Vautrin, Olivier Choussy, Wahib Ghanem, Rabah Taouachi, Julien Masliah Planchon, Ivan Bièche, Maud Kamal, Christophe Le Tourneau. Spatial and longitudinal tumor heterogeneity in head and neck squamous cell carcinoma patients treated with primary surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3363.

In vivo efficacy assessment of the CDK4/6 inhibitor palbociclib and the PLK1 inhibitor volasertib in human chordoma xenografts

Background

Management of advanced chordomas remains delicate considering their insensitivity to chemotherapy. Homozygous deletion of the regulatory gene CDKN2A has been described as the most frequent genetic alteration in chordomas and may be considered as a potential theranostic marker. Here, we evaluated the tumor efficacy of the CDK4/6 inhibitor palbociclib, as well as the PLK1 inhibitor volasertib, in three chordoma patient-derived xenograft (PDX) models to validate and identify novel therapeutic approaches.

Methods

From our chordoma xenograft panel, we selected three models, two of them harboring a homozygous deletion of CDKN2A/2B genes, and the last one a PBRM1 pathogenic variant (as control). For each model, we tested the palbociclib and volasertib drugs with pharmacodynamic studies together with RT-PCR and RNAseq analyses.

Results

For palbociclib, we observed a significant tumor response for one of two models harboring the deletion of CDKN2A/2B (p = 0.02), and no significant tumor response in the PBRM1-mutated PDX; for volasertib, we did not observe any response in the three tested models. RT-PCR and RNAseq analyses showed a correlation between cell cycle markers and responses to palbociclib; finally, RNAseq analyses showed a natural enrichment of the oxidative phosphorylation genes (OxPhos) in the palbociclib-resistant PDX (p = 0.02).

Conclusion

CDK4/6 inhibition appears as a promising strategy to manage advanced chordomas harboring a loss of CDKN2A/2B. However, further preclinical studies are strongly requested to confirm it and to understand acquired or de novo resistance to palbociclib, in the peculiar view of a targeting of the oxidative phosphorylation genes.

Human papilloma virus integration sites and genomic signatures in head and neck squamous cell carcinoma

A prevalence of around 26% of human papillomavirus (HPV) in head and neck squamous cell carcinoma (HNSCC) has been previously reported. HPV induced oncogenesis mainly involving E6 and E7 viral oncoproteins. In some cases, HPV viral DNA has been detected to integrate with the host genome and possibly contributes to carcinogenesis by affecting the gene expression. We retrospectively assessed HPV integration sites and signatures in 80 HPV positive patients with HNSCC, by using a double capture‐HPV method followed by next‐generation Sequencing. We detected HPV16 in 90% of the analyzed cohort and confirmed five previously described mechanistic signatures of HPV integration [episomal (EPI), integrated in a truncated form revealing two HPV‐chromosomal junctions colinear (2J‐COL) or nonlinear (2J‐NL), multiple hybrid junctions clustering in a single chromosomal region (MJ‐CL) or scattered over different chromosomal regions (MJ‐SC) of the human genome]. Our results suggested that HPV remained episomal in 38.8% of the cases or was integrated/mixed in the remaining 61.2% of patients with HNSCC. We showed a lack of association of HPV genomic signatures to tumour and patient characteristics, as well as patient survival. Similar to other HPV associated cancers, low HPV copy number was associated with worse prognosis. We identified 267 HPV‐human junctions scattered on most chromosomes. Remarkably, we observed four recurrent integration regions: PDL1/PDL2/PLGRKT (8.2%), MYC/PVT1 (6.1%), MACROD2 (4.1%) and KLF5/KLF12 regions (4.1%). We detected the overexpression of PDL1 and MYC upon integration by gene expression analysis. In conclusion, we identified recurrent targeting of several cancer genes such as PDL1 and MYC upon HPV integration, suggesting a role of altered gene expression by HPV integration during HNSCC carcinogenesis.

Prognostic Value of Fusobacterium nucleatum after Abdominoperineal Resection for Anal Squamous Cell Carcinoma

Main prognostic factors of anal squamous cell carcinoma (ASCC) are tumor size, differentiation, lymph node involvement, and male gender. However, they are insufficient to predict relapses after exclusive radiotherapy (RT) or chemoradiotherapy (CRT). Fusobacterium nucleatum has been associated with poor prognosis in several digestive cancers. In this study, we assessed the association between intratumoral F. nucleatum load and clinico-pathological features, relapse, and survival in patients with ASCC who underwent abdominoperineal resection (APR) after RT/CRT. We retrospectively analyzed surgical samples from a cohort of 166 patients with ASCC who underwent APR. F. nucleatum 16S rRNA gene sequences were quantified using real-time quantitative PCR. We associated F. nucleatum load with classical clinicopathological features, overall survival (OS), disease-free survival (DFS), and metastasis-free survival (MFS) using Cox regression univariate and multivariate analyses. Tumors harboring high loads of F. nucleatum (highest tercile) showed longer OS and DFS (median: not reached vs. 50.1 months, p = 0.01, and median: not reached vs. 18.3 months, p = 0.007, respectively). High F. nucleatum load was a predictor of longer OS (HR = 0.55, p = 0.04) and DFS (HR = 0.50, p = 0.02) in multivariate analysis. High F. nucleatum load is an independent favorable prognostic factor in patients with ASCC who underwent APR.

A Genotyping Study in Benin Comparing the Carriage of Plasmodium falciparum Infections Before Pregnancy and in Early Pregnancy: Story of a Persistent Infection

Background

Malaria infections in the first trimester of pregnancy are frequent and deleterious for both mother and child health. To investigate if these early infections are newly acquired or already present in the host, we assessed whether parasites detected before pregnancy and those detected in early pregnancy are the same infection.

Methods

We used data from the preconceptional “RECIPAL” study (Benin, 2014–2017). Sixty-three pregnant women of 411 included who had a malaria infection detected by quantitative polymerase chain reaction both before pregnancy and at the first antenatal care (ANC) visit were selected for this study. Two highly polymorphic markers, msp-2 and glurp, and a fragment-analysis method were used to enumerate the Plasmodium falciparum genotypes and to quantify their proportions within isolates. An infection was considered as persistent when identical msp-2 and glurp genotypes were found in the corresponding prepregnancy and early-pregnancy samples.

Results

The median time between the 2 malaria screenings was 3 months. The median gestational age at the first ANC visit was 6.4 weeks. Most infections before pregnancy were submicroscopic infections. Based on both msp-2 and glurp genotyping, the infection was similar before and in early pregnancy in 46% (29/63) of cases.

Conclusions

Almost half of P. falciparum infections detected in the first trimester originate before pregnancy. Protecting young women from malaria infection before pregnancy might reduce the prevalence of malaria in early pregnancy and its related poor maternal and birth outcomes.

Phase-contrast 3D tomography of HeLa cells grown in PLLA polymer electrospun scaffolds using synchrotron X-rays

Advanced imaging is useful for understanding the three-dimensional (3D) growth of cells. X-ray tomography serves as a powerful noninvasive, nondestructive technique that can fulfill these purposes by providing information about cell growth within 3D platforms. There are a limited number of studies taking advantage of synchrotron X-rays, which provides a large field of view and suitable resolution to image cells within specific biomaterials. In this study, X-ray synchrotron radiation microtomography at Diamond Light Source and advanced image processing were used to investigate cellular infiltration of HeLa cells within poly L-lactide (PLLA) scaffolds. This study demonstrates that synchrotron X-rays using phase contrast is a useful method to understand the 3D growth of cells in PLLA electrospun scaffolds. Two different fiber diameter (2 and 4 µm) scaffolds with different pore sizes, grown over 2, 5 and 8 days in vitro, were examined for infiltration and cell connectivity. After performing visualization by segmentation of the cells from the fibers, the results clearly show deeper cell growth and higher cellular interconnectivity in the 4 µm fiber diameter scaffold. This indicates the potential for using such 3D technology to study cell-scaffold interactions for future medical use.

[Anaesthesia for caesarean section in a pregnant woman with cor triatriatum]

A 41-year-old woman suffering from a left cor triatrium, pregnant for the first time, was hospitalized for a caesarean section in the context of a pulmonary arterial hypertension with severe anaemia. The anaesthetic strategy which was decided on involved setting up a haemodynamic monitoring prior to induction of a general anaesthetia with etomidate, remifentanil and succinylcholine and maintained with propofol, sufentanil and cisatracurium. This strategy allowed the hemodynamic to be stabilized during the operation. The improvement of the arterial pulmonary hypertension immediately after coming out of the operating theatre allowed the patient to be briefly monitored in the intensive care unit and to be allowed home on the 10th day following the operation. The patient's cardiopathy was corrected in the 5th month after the birth.

[Evaluating a policy of restrictive episiotomy before and after practice guidelines by the French College of Obstetricians and Gynecologists]

AIM

To evaluate our practice following Clinical Practice Guidelines (CPG) of the French College of Obstetricians and Gynecologists (CNGOF) in 2005 advocating a policy of restrictive episiotomy and to show that a significative decrease in the rate of episiotomy does not increase the number of third and fourth degree perineal tears.

MATERIAL AND METHODS

A retrospective study of episiotomies and third/fourth degree perineal tears of the year 2003 (before the CPG) was compared with the year 2007 (after the CPG). We analyzed the indications of episiotomies and compared the rate of episiotomies and severe perineal tears between the two periods.

RESULTS

In 2003, the rate of episiotomies was 18.8% (upon 1755 vaginal deliveries). We observed 16 (9 per thousand) third-degree perineal tears, five of which was associated with episiotomies; and two (1 per thousand) fourth-degree perineal tears. In 2007, the rate of episiotomies was 3.4% (upon 1940 vaginal deliveries). There were eight (4 per thousand) third-degree and four (2 per thousand) fourth-degree perineal tears. The two periods of study were similar in terms of age, parity, gestational age, birthweight, rate of spontaneous deliveries, breech and instrumental deliveries. There were a difference regarding deliveries in the occipitoposterior position (5.8% vs 13.8% ; p=0.02). No significant difference was found between the rates of third degree (9 per thousand vs 4 per thousand ; p=0.059) and fourth degree perineal tears (1 per thousand vs 2 per thousand ; p=0.487). However, there was a significant decrease in the rate of episiotomies between the two periods (18.8% vs 3.4% ; p<0.001).

CONCLUSION

An episiotomy rate of 3.4% is much lower than the threshold rate of 30% recommanded. A policy of restrictive episiotomy is possible without increasing the rate of severe perineal tears. Aknowledging the risks and benefits of each obstetrical procedure might decrease the number of episiotomies, whose practice should be evaluated in every labour ward.

[Spontaneous rupture of the unscarred uterus during labor. Case report]

We report a case of spontaneous uterine rupture in a 19 year-old patient Gravida 1 para 2 with no past history of uterine surgery. The diagnosis of uterine rupture, evoked in the early post-partum in the presence of acute abdominal pain, collapsus and haemoperitoneum on ultrasonography, was confirmed by laparotomy. Treatment consisted in hysterorrhaphy. The etiopathogenesis, clinical and therapeutical aspects of spontaneous unscarred uterine ruptures are discussed throughout a literature review.

[Severe shoulder dystocia: study of 14 cases treated by Jacquemier's maneuver]

OBJECTIVE

Shoulder dystocia is a dreadful complication of vaginal deliveries since it can be responsible of brachial plexus palsies and even neonatal deaths. Unlike most studies, we defined shoulder dystocia as the enclosing of fetal shoulders above the superior strait (cavity station of 1cm) and situations being resolved only by delivery of the posterior arm (Jacquemier's maneuver). The purpose of this study was to analyze cases of shoulder dystocia in terms of maternal and neonatal complications and to compare risk factors with those identified in the literature.

MATERIAL AND METHODS

We conducted a retrospective study of 14 cases of severe shoulder dystocia (SSD) which occurred at our hospital between January 1995 and January 2007. TSD was diagnosed in the absence of engagement of both fetal shoulders requiring recourse to Jacquemier's maneuver for delivery. Any gestational diabetes, abnormal progression of labour, suspicion or existence of fetal macrosomia, instrumental delivery, and neonatal complications were noted.

RESULTS

The incidence of SSD was around 1 per thousand. Multiparity, weight gain greater than 15kg and gestational diabetes were moderately present in our study group. Only 20% of neonates were macrosomic and 50% had a birth-weight of less than 4000g. In 80% of cases, an instrumental extraction was practised. Brachial plexus injuries affected 20% of neonates, no fracture was observed, one child died following an unresolved SSD.

CONCLUSION

This series shows that the incidence of SSD is rare and difficultly predictable even though identified risk factors exist. However, an instrumental extraction seems frequently associated with SSD and any extraction should take into account the presence of known risk factors. In spite of the severity of our cases of shoulder dystocia, complications found seemed to be similar to those observed in the literature.

[Instrumental extractions using Thierry's spatulas: evaluation of the risk of perineal laceration according to occiput position in operative deliveries]

OBJECTIVE

Risk factors for severe perineal lacerations are nowadays well-known and they include operative vaginal deliveries and extractions in occiput posterior (OP) positions. The aim of this study was to assess whether OP position increases the risk for anal sphincter injury when compared with occiput anterior (OA) positions in operative deliveries using Thierry's spatulas.

METHODS

Retrospective study of 163 extractions with Thierry's spatulas over a five-year period (January 2000 to December 2005) performed in a general hospital. Singleton cephalic pregnancies at term were studied and the incidence of severe perineal lacerations was noted in deliveries in OP and OA positions.

RESULTS

In these 163 cases, the varieties of presentation obtained by vaginal examination were 129 in anterior and 34 in posterior positions. Eleven posterior positions rotated anteriorly on delivery and 23 remained in a posterior position. The OA group (n=140) and the OP group (n=23) were constituted. Anal sphincter injury occurred significantly more often in the OP group compared with the OA group (17.4% versus 2.9%, p=0.014) with an odds ratio of 7.1 (95% CI 1.6-31). Only one fourth-degree laceration was noted. Within the OP group, the incidence of vaginal lacerations was increased compared to the OA group, but without any significant difference (43.5% versus 27.9%, p=0.20). In a logistic regression model, the OP position was 6.4 times (95% CI 1.3-31.5) more likely to be associated with anal sphincter injury than OA position. The incidence of OP position was 14.1% within the whole population studied and Thierry's spatulas permit anterior rotations of occipito posterior presentation in only 32.4% of cases.

CONCLUSION

The efficiency of Thierry's spatulas is proven. As with forceps and vacuum extractors, extraction with Thierry's spatulas is a risk factor for perineal laceration compared to a spontaneous delivery. In deliveries with spatulas, OP head positions further increase this perineal risk against OA positions. OP positions before fetal extractions do not seem to be an ideal situation for using spatulas, even if an anterior rotation is achieved in one-third of cases.

Hémorragie de la délivrance « menaçant la vie » et utilisation du facteur VII recombinant activé rFVIIa NovoSeven®

Postpartum haemorrhage remains a dangerous obstetrical complication, which is the main cause of maternal mortality in developing countries. The diagnosis must be immediate and its management is both medically and surgically in life-threatening haemorrhage. We present a case of a thirty-three-year-old woman who asked a pregnancy interruption for premature rupture of membranes at 21(th) gestational week for her second pregnancy; she underwent a caesarean section at term for her first pregnancy. She delivered vaginally and developed a postpartum haemorrhage with hemorrhagic shock which was resistant to medical, surgical and radiological management. We decided to use recombinant activated factor VII (rFVIIa, NovoSeven) as a final attempt to rescue the patient. During surgery, two intravenous bolus injections (60, 120 mug/kg) were successfully given with a control of bleeding and haemoglobin. The patient developed later a splenic thrombosis that can be related to either rFVIIa or to the hypovolemic shock or to the sepsis. Recombinant activated factor VII is an interesting and promising haemostatic agent in the management of life-threatening postpartum haemorrhage unresponsive to conventional treatment.

[Liberal versus restrictive practice of episiotomy: do there exist specific obstetrical indications for episiotomy?]

PURPOSE

To analyze the literature comparing two different policies for episotomy practice: liberal versus restrictive use. To search and discuss specific indications for episiotomy.

METHODS

The Medline base was analyzed from 1970 to 2005. The articles where selected by using the key word episiotomy and selective or restrictive and routine or liberal. Every potential indications was crossed with episotomy.

RESULTS

A policy implying a liberal practice of episiotomy is not better compared to a restrictive policy. The evidence-based medical literature favors avoiding routine episiotomy in low risk deliveries. Data are quite scarce concerning the different specific indications for episiotomy, and finally we can retain only one specific indication which is the short perineum when the distance between the fourchette and the center of the anus is less than 3 cm. Nevertheless, in order to improve delivery conditions obstetricians can advisably use episiotomy in accordance with their clinical assessment.

CONCLUSION

There is no evidence in the literature favoring a liberal policy over a restrictive policy for the use of episiotomy, both in terms of fetal (Grade C) and maternal (Grade A) indications. A number of obstetrical situations considered as at risk do not systematically indicate an episiotomy. There are however circumstances in which a pertinent and prudent clinical assessment will lead the obstetrician to use an episiotomy.

[Ectopic pregnancy management: cervical and abdominal pregnancies]

Cervical or abdominal pregnancies are rare forms of ectopic pregnancy and their management differs for different authors. Besides, the literature is mainly made of case-reports. The aim is to propose one or more management possibilities, keeping in mind that the level of proof obtained from the references used is insufficient to be affirmative. For cervical pregnancy, although hysterectomy is the reference treatment (especially in advanced pregnancy or hemorrhagic life-threatening forms), technical improvements in ultrasonography make feasible the diagnosis of non or weakly symptomatic forms, which could be treated conservatively in order to preserve fertility of these women. In this diagnostic situation the present treatment standard is methotrexate combined with intra-amniotic feticide in case of viable cervical pregnancy. Diagnosis of abdominal pregnancy is often made late. Treatment consists in laparotomy which enables better vascular control. Placental ablation remains as often as not dangerous and in most cases, it is better to abandon the attempt.