Robotic retroperitoneal lymph node dissection for primary and post-chemotherapy testis cancer.

The role of retroperitoneal lymph node dissection (RPLND) in testicular cancer is well established in both the primary and post-chemotherapy setting. The aim of this study was to report our 2 years oncological outcomes of robotic RPLND. A retrospective review was performed of all patients undergoing robotic RPLND by a single surgeon at Princess Margaret Cancer Centre. Demographic, perioperative, and oncologic data were analyzed using descriptive statistics. Between September 2014 and June 2020, 141 patients underwent an RPLND [33 (23.4%) were primary, 108 (76.6%) were post-chemotherapy]. 27 (19.1%) patients underwent a robotic bilateral template nerve-sparing RPLND. RPLND indication was primary (i.e. pre-chemotherapy) in 18 (66.7%), and post-chemotherapy in 9 (33.3%) patients. Stage at RPLND was 2A (n = 15, 55.6%), 2B (n = 9, 33.3%), 2C (n = 1, 3.7%) and 3 (n = 2, 7.4%). Median OR time (incision to closure) was 525 min and blood loss was 200 ml. Nerve sparing was performed in all but one case. Six (22.2%) adjuvant procedures were performed including two (7.4%) vascular repairs. Median length of stay was 2 days. Viable tumor was detected in 17 (63%) and teratoma in 9 (33.3%). Median follow-up was 31.3 months. No adjuvant chemotherapy was given. Three patients (11.1%) relapsed: 2 out-of-field and 1 with both in-field and out-of-field disease. Robotic RPLND can be performed safely. Long-term follow-up of series such as ours, enriched with patients with viable disease and/or teratoma, and not treated with adjuvant chemotherapy is required to ensure oncological outcomes are comparable to the open approach.

Partial orchiectomy: The Princess Margaret cancer centre experience.

INTRODUCTION: Radical orchiectomy (RO) is the standard treatment for a testis cancer. Organ sparing surgery can be considered in the setting of a solitary functioning testis or bilateral tumors. It has also been suggested as an alternative to RO for small lesions. In this study we report our partial orchiectomy (PO) experience. METHODS: We performed a retrospective review using our prospectively maintained database analyzing PO. RESULTS: Between 1983 and 2018, 77 patients underwent PO. Mean age was 31.3 years (range 17-56). A lesion was palpable in 70 (90.9%) and median lesion size 14.1 mm (range 3-35 mm). Reasons for PO included ``small lesion" in 39 (50.6%); solitary functioning testis in 30 (39%); bilateral lesions in 6 (7.8%); or assumed benign lesion in 1 (1.3%). Median follow-up was 43.5 months (range 1-258). Lesion histology was benign in 25 (32.5%). A positive surgical margin was noted in 6 (7.8%) with none developing local or distant recurrence. Sixteen (20.8%) patients underwent salvage ipsilateral RO at a median of 3 months (range 0-46). Reasons for salvage RO included a radiologically detected lesion in 7, palpable lesion in 4, positive surgical margin in 3 and adverse pathology in 2 patients. Malignant histology was present in 12 (75%) of the salvage RO specimens. There were no reported Clavien-Dindo Grade 3 to 5 complications. CONCLUSION: Organ sparing surgery is a safe and feasible approach to small testis lesions. For the third with benign disease, and even those with malignant histology, a RO can be avoided in carefully selected patients.

The glial cells missing-1 protein is essential for branching morphogenesis in the chorioallantoic placenta.

Trophoblast cells of the placenta are established at the blastocyst stage and differentiate into specialized subtypes after implantation. In mice, the outer layer of the placenta consists of trophoblast giant cells that invade the uterus and promote maternal blood flow to the implantation site by producing cytokines with angiogenic and vasodilatory actions. The innermost layer, called the labyrinth, consists of branched villi that provide a large surface area for nutrient transport and are composed of trophoblast cells and underlying mesodermal cells derived from the allantois. The chorioallantoic villi develop after embryonic day (E) 8.5 through extensive folding and branching of an initially flat sheet of trophoblast cells, the chorionic plate, in response to contact with the allantois. We show here that Gcm1, encoding the transcription factor glial cells missing-1 (Gcm1), is expressed in small clusters of chorionic trophoblast cells at the flat chorionic plate stage and at sites of chorioallantoic folding and extension when morphogenesis begins. Mutation of Gcm1 in mice causes a complete block to branching of the chorioallantoic interface, resulting in embryonic mortality by E10 due to the absence of the placental labyrinth. In addition, chorionic trophoblast cells in Gcm1-deficient placentas do not fuse to form syncytiotrophoblast. Abnormal development of placental villi is frequently associated with fetal death and intrauterine growth restriction in humans, and our studies provide the earliest molecular insight into this aspect of placental development.

Periodic expression of the cyclin-dependent kinase inhibitor p57(Kip2) in trophoblast giant cells defines a G2-like gap phase of the endocycle.

Endoreduplication is an unusual form of cell cycle in which rounds of DNA synthesis repeat in the absence of intervening mitoses. How G1/S cyclin-dependent kinase (Cdk) activity is regulated during the mammalian endocycle is poorly understood. We show here that expression of the G1/S Cdk inhibitor p57(Kip2) is induced coincidentally with the transition to the endocycle in trophoblast giant cells. Kip2 mRNA is constitutively expressed during subsequent endocycles, but the protein level fluctuates. In trophoblast giant cells synchronized for the first few endocycles, the p57(Kip2) protein accumulates only at the end of S-phase and then rapidly disappears a few hours before the onset of the next S-phase. The protein becomes stabilized by mutation of a C-terminal Cdk phosphorylation site. As a consequence, introduction of this stable form of p57(Kip2) into giant cells blocks S-phase entry. These data imply that p57(Kip2) is subject to phosphorylation-dependent turnover. Surprisingly, although this occurs in endoreduplicating giant cells, p57(Kip2) is stable when ectopically expressed in proliferating trophoblast cells, indicating that these cells lack the mechanism for protein targeting and/or degradation. These data show that the appearance of p57(Kip2) punctuates the completion of DNA replication, whereas its turnover is subsequently required to initiate the next round of endoreduplication in trophoblast giant cells. Cyclical expression of a Cdk inhibitor, by terminating G1/S Cdk activity, may help promote the resetting of DNA replication machinery.

The HAND1 basic helix-loop-helix transcription factor regulates trophoblast differentiation via multiple mechanisms.

The basic helix-loop-helix (bHLH) transcription factor genes Hand1 and Mash2 are essential for placental development in mice. Hand1 promotes differentiation of trophoblast giant cells, whereas Mash2 is required for the maintenance of giant cell precursors, and its overexpression prevents giant cell differentiation. We found that Hand1 expression and Mash2 expression overlap in the ectoplacental cone and spongiotrophoblast, layers of the placenta that contain the giant cell precursors, indicating that the antagonistic activities of Hand1 and Mash2 must be coordinated. MASH2 and HAND1 both heterodimerize with E factors, bHLH proteins that are the DNA-binding partners for most class B bHLH factors and which are also expressed in the ectoplacental cone and spongiotrophoblast. In vitro, HAND1 could antagonize MASH2 function by competing for E-factor binding. However, the Hand1 mutant phenotype cannot be solely explained by ectopic activity of MASH2, as the Hand1 mutant phenotype was not altered by further mutation of Mash2. Interestingly, expression of E-factor genes (ITF2 and ALF1) was down-regulated in the trophoblast lineage prior to giant cell differentiation. Therefore, suppression of MASH2 function, required to allow giant cell differentiation, may occur in vivo by loss of its E-factor partner due to loss of its expression and/or competition from HAND1. In giant cells, where E-factor expression was not detected, HAND1 presumably associates with a different bHLH partner. This may account for the distinct functions of HAND1 in giant cells and their precursors. We conclude that development of the trophoblast lineage is regulated by the interacting functions of HAND1, MASH2, and their cofactors.

Drosophila engrailed can substitute for mouse Engrailed1 function in mid-hindbrain, but not limb development.

The Engrailed-1 gene, En1, a murine homologue of the Drosophila homeobox gene engrailed (en), is required for midbrain and cerebellum development and dorsal/ventral patterning of the limbs. In Drosophila, en is involved in regulating a number of key patterning processes including segmentation of the epidermis. An important question is whether, during evolution, the biochemical properties of En proteins have been conserved, revealing a common underlying molecular mechanism to their diverse developmental activities. To address this question, we have replaced the coding sequences of En1 with Drosophila en. Mice expressing Drosophila en in place of En1 have a near complete rescue of the lethal En1 mutant brain defect and most skeletal abnormalities. In contrast, expression of Drosophila en in the embryonic limbs of En1 mutants does not lead to repression of Wnt7a in the embryonic ventral ectoderm or full rescue of the embryonic dorsal/ventral patterning defects. Furthermore, neither En2 nor en rescue the postnatal limb abnormalities that develop in rare En1 null mutants that survive. These studies demonstrate that the biochemical activity utilized in mouse to mediate brain development has been retained by Engrailed proteins across the phyla, and indicate that during evolution vertebrate En proteins have acquired two unique functions during embryonic and postnatal limb development and that only En1 can function postnatally.

The Hand1 bHLH transcription factor is essential for placentation and cardiac morphogenesis.

The placenta and cardiovascular system are the first organ systems to form during mammalian embryogenesis. We show here that a single gene is critical for development of both. The Hand1 gene, previously called Hxt, eHAND and Thing1, encodes a basic helix-loop-helix (bHLH) transcription factor that starts to be expressed during pre-implantation development. After implantation, Hand1 expression is restricted to placental trophoblast cells and later to embryonic cardiac and neural crest cells. We generated Hand1-null mutant mice by gene targetting. Homozygous mutant embryos arrested by embryonic day (E) 7.5 of gestation with defects in trophoblast giant cell differentiation. This early mortality could be rescued by aggregation of mutant embryos with wild-type tetraploid embryos, which contribute wild-type cells to the trophoblast, but not the embryo. By E10.5, however, the Hand1-null fetuses derived from tetraploid chimaeras died due to cardiac failure. Their heart tubes showed abnormal looping and ventricular myocardial differentiation. Therefore, Hand1 is essential for differentiation of both trophoblast and cardiomyocytes, which are embryologically distinct cell lineages.

Rescue of the En-1 mutant phenotype by replacement of En-1 with En-2.

The related mouse Engrailed genes En-1 and En-2 are expressed from the one- and approximately five-somite stages, respectively, in a similar presumptive mid-hindbrain domain. However, mutations in En-1 and En-2 produce different phenotypes. En-1 mutant mice die at birth with a large mid-hindbrain deletion, whereas En-2 mutants are viable, with cerebellar defects. To determine whether these contrasting phenotypes reflect differences in temporal expression or biochemical activity of the En proteins, En-1 coding sequences were replaced with En-2 sequences by gene targeting. This rescued all En-1 mutant defects, demonstrating that the difference between En-1 and En-2 stems from their divergent expression patterns.

Identification of a gene from Xp21 with similarity to the tctex-1 gene of the murine t complex.

Long range physical mapping within the p21 region of the X chromosome identified a CpG rich island approximately 180 kb centromeric to the chronic granulomatous disease (CGD) locus. The segments adjacent to the CpG island hybridized to discrete bands in DNAs of several species and when used to screen retinal cDNA libraries led to the identification of cDNAs that detected a mRNA of 2.1 kb in many tissues. Molecular characterization of corresponding genomic clones of this novel human gene confirmed the origin of the cDNA clones and indicated a genomic structure with five exons spanning a total of 9 kb. The complete cDNA sequence revealed that this gene contained a putative open reading frame of 116 amino acids with a 3' untranslated region of 1.74 kb. The amino acid sequence shows a high degree of similarity to the predicted product of the tctex-1 gene of the mouse t complex. As linkage studies and patients with deletions have implicated the Xp21 region as containing the retinitis pigmentosa defect (RP3), the gene was assessed as a candidate disease gene in RP3 families. A single base pair polymorphism was identified within the coding region but no disease associated changes were found by single strand conformational polymorphism and sequencing analysis of amplified exons of 20 RP patients. Analysis of a dinucleotide repeat polymorphism within this gene in families affected with RP3 suggested refinement of the RP3 region.

Linkage analysis in X-linked ocular albinism.

We studied the linkage of X-linked Nettleship-Falls ocular albinism (OA1) to Xp22.1-Xp22.3 RFLPs at 12 loci in five families, including one in which OA1 cosegregates with a deletion of steroid sulfatase (STS). We found evidence for tight linkage of OA1 to the Xp22.3 loci DXS143, STS, and DXS452. DXS452, a newly described polymorphism detected by the probe E25B1.8, is part of the sequence family "DXS278" (pCRI-S232), but represents a single genetic locus. Every female in this study was heterozygous for the DXS452 RFLP. Thus, this marker will be extremely useful for family studies and genetic counseling. Analysis of individual recombinations suggests that OA1 maps between DXS143 and DXS85. Multipoint linkage analysis was consistent with this localization but was not statistically significant. These data suggest that OA1 lies proximal to the deletion in a previously described family with OA1 and STS deletion, but maps within the Xp22.3-Xp22.2 region.

Multipoint linkage analysis and heterogeneity testing in 20 X-linked retinitis pigmentosa families.

Using multipoint linkage analysis in 20 families segregating for X-linked retinitis pigmentosa (XLRP), the lod scores on a map of eight RFLP loci were obtained. Our results indicate that under the hypothesis of homogeneity the maximal multipoint lod score supports one disease locus located slightly distal to OTC at Xp21.1. Heterogeneity testing for two XLRP loci suggested that a second XLRP locus may be located 8.5 cM proximal to DXS28 at Xp21.3. Further heterogeneity testing for three disease loci failed to detect a third XLRP locus proximal to DXS7 in any of our 20 XLRP families.

Assignment of the gene for complete X-linked congenital stationary night blindness (CSNB1) to Xp11.3.

X-linked congenital stationary night blindness (CSNB) is a nonprogressive retinal disorder characterized by a presumptive defect of neurotransmission between the photoreceptor and bipolar cells. Carriers are not clinically detectable. A new classification for CSNB includes a complete type, which lacks rod function by electroretinography and dark adaptometry, and an incomplete type, which shows some rod function on scotopic testing. The refraction in the complete CSNB patients ranges from mild to severe myopia; the incomplete ranges from moderate hyperopia to moderate myopia. To map the gene responsible for this disease, we studied eight multigeneration families, seven with complete CSNB (CSNB1) and one with incomplete CSNB, by linkage analysis using 17 polymorphic X-chromosome markers. We found tight genetic linkage between CSNB1 and an Xp11.3 DNA polymorphic site, DXS7, in seven families with CSNB1 (LOD 7.35 at theta = 0). No recombinations to CSNB1 were found with marker loci DXS7 and DXS14. The result with DXS14 may be due to the small number of scored meioses (10). No linkage could be shown with Xq loci PGK, DXYS1, DXS52, and DXS15. Pairwise linkage analysis maps the gene for CSNB1 at Xp11.3 and suggests that the CSNB1 locus is distal to another Xp11 marker, TIMP, and proximal to the OTC locus. Five-point analysis on the eight families supported the order DXS7-CSNB1-TIMP-DXS225-DXS14. The odds in favor of this order were 9863:1. Removal of the family with incomplete CSNB (F21) revealed two most favored orders, DXS7-CSNB1-TIMP-DXS255-DXS14 and CSNB1-DXS7-TIMP-DXS255-DXS14. Heterogeneity testing using the CSNB1-M27 beta and CSNB1-TIMP linkage data (DXS7 was not informative in F21) was not significant to support evidence of genetic heterogeneity (P = 0.155 and 0.160, respectively).

Linkage analysis of a large Latin-American family with X-linked retinitis pigmentosa and metallic sheen in the heterozygote carrier.

An extended linkage analysis was performed on the large Latin-American kindred with X-linked retinitis pigmentosa (XLRP) and metallic sheen in the heterozygous carrier studied and reported previously by R.L. Nussbaum et al. (1985, Hum. Genet. 70:45-50) and on a smaller family with the same XLRP variant. In these kindreds the XLRP locus shows close linkage with Xp21 marker loci OTC and DXS206. The results of this linkage analysis agree with the observations made by Nussbaum et al. (1985) that an XLRP locus is distal to DXS7.

Localization of the gene for X-linked recessive type of retinitis pigmentosa (XLRP) to Xp21 by linkage analysis.

The X-linked recessive type of retinitis pigmentosa (XLRP) causes progressive night blindness, visual field constriction, and eventual blindness in affected males by the third or fourth decade of life. The biochemical basis of the disease is unknown, and prenatal diagnosis and definitive carrier diagnosis remain elusive. Heterogeneity in XLRP has been suggested by linkage studies of families affected with XLRP and by phenotypic differences observed in female carriers. Localization of XLRP near Xp11.3 has been suggested by close linkage to an RFLP at the locus DXS7 (Xp11.3) detected by probe L1.28. In other studies a locus for XLRP with metallic sheen has been linked to the ornithine transcarbamylase (OTC) locus mapping to the Xp21 region. In this study, by linkage analysis using seven RFLP markers between Xp21 and Xcen, we examined four families with multiple affected individuals. Close linkage was found between XLRP and polymorphic sites OTC (theta = .06 with lod 5.69), DXS84 (theta = .05 with lod 4.08), and DXS206 (theta = .06 with lod 2.56), defined by probes OTC, 754, and XJ, respectively. The close linkage of OTC, 754, and XJ to XLRP localizes the XLRP locus to the Xp21 region. Data from recombinations in three of four families place the locus above L1.28 and below the Duchenne muscular dystrophy (DMD) gene, consistent with an Xp21 localization. In one family, however, one affected male revealed a crossover between XLRP and all DNA markers, except for the more distal DXS28 (C7), while his brother is recombined for this marker (C7) and not other, more proximal markers. This suggests that in this family the XLRP mutation maps near DXS28 and above the DMD locus.

Bloom syndrome: a single complementation group defines patients of diverse ethnic origin.

Patients of diverse ethnic background were recruited in order to examine whether genetic heterogeneity could be demonstrated in Bloom syndrome (BS). Although most cells from BS patients exhibit high sister-chromatid exchange (SCE), lymphoid cells from some patients exhibit dimorphism for high and low SCE. We addressed the issue of dominance or recessivity of the low-SCE BS phenotype. A high-SCE lymphoblast line, HB1, was mutagenized, and a clone, HB10T, carrying the markers ouabain resistance and thioguanine resistance, was isolated to serve as a fusion parent. Two independent low-SCE BS lines were fused with HB10T, and hybrids were selected in HAT medium supplemented with ouabain. The hybrids, which were tetraploid, exhibited the expected phenotypes when exposed to ouabain and thioguanine. In every case, these hybrids had low SCE levels, establishing dominance of the low-SCE phenotype. The same methodology was also used to assess genetic heterogeneity in BS. A complementation analysis was carried out using high-SCE lymphoblast cell lines derived from BS patients. HB10T was fused with five other high-SCE BS lines. No correction of the high SCE characteristic of BS cells was seen in hybrid lines derived from patients of Ashkenazi Jewish, French-Canadian, Mennonite, or Japanese extraction. Thus, a single gene is responsible for the high-SCE phenotype in BS patients of diverse ethnic origin.