Human Mutated MYOT and CRYAB Genes Cause a Myopathic Phenotype in Zebrafish

Myofibrillar myopathies (MFMs) are a group of hereditary neuromuscular disorders sharing common histological features, such as myofibrillar derangement, Z-disk disintegration, and the accumulation of degradation products into protein aggregates. They are caused by mutations in several genes that encode either structural proteins or molecular chaperones. Nevertheless, the mechanisms by which mutated genes result in protein aggregation are still unknown. To unveil the role of myotilin and αB-crystallin in the pathogenesis of MFM, we injected zebrafish fertilized eggs at the one-cell stage with expression plasmids harboring cDNA sequences of human wildtype or mutated MYOT (p.Ser95Ile) and human wildtype or mutated CRYAB (p.Gly154Ser). We evaluated the effects on fish survival, motor behavior, muscle structure and development. We found that transgenic zebrafish showed morphological defects that were more severe in those overexpressing mutant genes. which developed a myopathic phenotype consistent with that of human myofibrillar myopathy, including the formation of protein aggregates. Results indicate that pathogenic mutations in myotilin and αB-crystallin genes associated with MFM cause a structural and functional impairment of the skeletal muscle in zebrafish, thereby making this non-mammalian organism a powerful model to dissect disease pathogenesis and find possible druggable targets.

Rare Single Nucleotide and Copy Number Variants and the Etiology of Congenital Obstructive Uropathy: Implications for Genetic Diagnosis

SIGNIFICANCE STATEMENT

Congenital obstructive uropathy (COU) is a prevalent human developmental defect with highly heterogeneous clinical presentations and outcomes. Genetics may refine diagnosis, prognosis, and treatment, but the genomic architecture of COU is largely unknown. Comprehensive genomic screening study of 733 cases with three distinct COU subphenotypes revealed disease etiology in 10.0% of them. We detected no significant differences in the overall diagnostic yield among COU subphenotypes, with characteristic variable expressivity of several mutant genes. Our findings therefore may legitimize a genetic first diagnostic approach for COU, especially when burdening clinical and imaging characterization is not complete or available.

BACKGROUND

Congenital obstructive uropathy (COU) is a common cause of developmental defects of the urinary tract, with heterogeneous clinical presentation and outcome. Genetic analysis has the potential to elucidate the underlying diagnosis and help risk stratification.

METHODS

We performed a comprehensive genomic screen of 733 independent COU cases, which consisted of individuals with ureteropelvic junction obstruction ( n =321), ureterovesical junction obstruction/congenital megaureter ( n =178), and COU not otherwise specified (COU-NOS; n =234).

RESULTS

We identified pathogenic single nucleotide variants (SNVs) in 53 (7.2%) cases and genomic disorders (GDs) in 23 (3.1%) cases. We detected no significant differences in the overall diagnostic yield between COU sub-phenotypes, and pathogenic SNVs in several genes were associated to any of the three categories. Hence, although COU may appear phenotypically heterogeneous, COU phenotypes are likely to share common molecular bases. On the other hand, mutations in TNXB were more often identified in COU-NOS cases, demonstrating the diagnostic challenge in discriminating COU from hydronephrosis secondary to vesicoureteral reflux, particularly when diagnostic imaging is incomplete. Pathogenic SNVs in only six genes were found in more than one individual, supporting high genetic heterogeneity. Finally, convergence between data on SNVs and GDs suggest MYH11 as a dosage-sensitive gene possibly correlating with severity of COU.

CONCLUSIONS

We established a genomic diagnosis in 10.0% of COU individuals. The findings underscore the urgent need to identify novel genetic susceptibility factors to COU to better define the natural history of the remaining 90% of cases without a molecular diagnosis.

DHES0815A, a novel antibody-drug conjugate targeting HER2/neu, is highly active against uterine serous carcinomas in vitro and in vivo

OBJECTIVE

Uterine serous carcinoma (USC) is an aggressive histologic variant of endometrial cancer which portends a poor prognosis. DHES0815A is a novel antibody-drug-conjugate (ADC) which binds specifically to HER2 overexpressing tumors at a distinct epitope from that bound by trastuzumab and pertuzumab after which it delivers the toxic payload, PBD-MA, a DNA mono-alkylating agent. The objective of this study was to evaluate the preclinical activity of DHES0815A against primary USC cell lines and xenografts.

METHODS

Twelve primary USC cell lines were assessed by immunohistochemistry (IHC) for HER2 protein expression and for C-erbB2 gene amplification using fluorescent in situ hybridization (FISH) analysis. Cell viability and bystander killing in USC cell lines after exposure to DHES0815A, the non-targeted ADC, and the unconjugated antibody (i.e. MHES0488A) were evaluated using flow cytometry-based-assays. In vivo activity of DHES0815A was tested against HER2/neu overexpressing USC xenografts.

RESULTS

High HER2/neu protein expression was seen in 25% (3/12) of the primary USC cell lines. USC cell lines overexpressing HER2/neu were significantly more sensitive to DHES0815A when compared to the non-targeted control ADC (p < 0.001). DHES0815A did not induce significant bystander killing of HER2/neu negative tumors when admixed with HER2/neu positive tumors. DHES0815A caused growth-inhibition and increased survival in USC HER2/neu overexpressing xenografts when compared to controls (p < 0.01).

CONCLUSIONS

DHES0815A is both highly selective and toxic to USC tumors overexpressing HER2/neu both in vitro and in vivo. HER2-directed ADCs, alone or in combination with other HER2/neu targeted agents may represent a novel treatment option for patients with tumors harboring HER2/neu overexpression refractory to trastuzumab and traditional chemotherapy.

Abstract 911: In vitro and in vivo activity of DHES0815A, an antibody-drug conjugate targeting HER2/neu in uterine serous carcinoma

Objective: Uterine serous carcinoma (USC) is an aggressive histologic variant of endometrial cancer which portends a poor prognosis. DHES0815A is a novel antibody-drug-conjugate (ADC) which binds specifically to HER2 overexpressing tumors at a distinct epitope from that bound by trastuzumab and pertuzumab after which it delivers the toxic payload, PBD-MA, a DNA mono-alkylating agent. The objective of this study was to evaluate the preclinical activity of DHES0815A against primary USC cell lines and xenografts.

Methods: Twelve primary USC cell lines were assessed by immunohistochemistry (IHC) for HER2 protein expression and for C-erbB2 gene amplification using fluorescent in situ hybridization (FISH) analysis. Cell viability and bystander killing in USC cell lines after exposure to DHES0815A, the non-targeted ADC, and the unconjugated antibody (i.e. MHES0488A) were evaluated using flow cytometry-based-assays. In vivo activity of DHES0815A was tested against HER2/neu overexpressing USC xenografts.

Results: High HER2/neu protein expression was seen in 25% (3/12) of the primary USC cell lines. USC cell lines overexpressing HER2/neu were significantly more sensitive to DHES0815A when compared to the non-targeted control ADC (p&lt;0.001). DHES0815A did not induce significant bystander killing of HER2/neu negative tumors when admixed with HER2/neu positive tumors. DHES0815A caused growth-inhibition and increased survival in USC HER2/neu overexpressing xenografts when compared to controls (p&lt;0.01).

Conclusions: DHES0815A is both highly selective and toxic to USC tumors overexpressing HER2/neu both in vitro and in vivo. HER2-directed ADCs, alone or in combination with other HER2/neu targeted agents may represent a novel treatment option for patients with tumors harboring HER2/neu overexpression refractory to trastuzumab and traditional chemotherapy.

Citation Format: Joan Tymon R. Tymon-Rosario, Elena Bonazzoli, Stefania Bellone, Arancha Manzano, Paola Manara, Luca Zammataro, Silvia Pelligra, Adele Guglielmi, Barbara Gnutti, Burak Zeybek, Justin Harold, Dennis Mauricio, Elena Ratner, Peter Schwartz, Alessandro D. Santin. In vitro and in vivo activity of DHES0815A, an antibody-drug conjugate targeting HER2/neu in uterine serous carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 911.

Abstract 5341: Derangements in HUWE1/c-MYC pathway confer sensitivity to the BET bromodomain inhibitor GS-626510 in uterine cervical carcinoma

Purpose: The prognosis for women with advanced or recurrent cervical cancer (CC) no longer responsive to radiation and/or chemotherapy remains poor. Whole-exome-sequencing (WES) studies have recently reported c-MYC gene amplification and HUWE1 gene mutations in a significant number of CC suggesting the HUWE1/c-MYC pathway as potential therapeutic target. We investigated HUWE1 and c-MYC expression in fresh-frozen CC and the potential activity of the novel BET bromodomain inhibitor GS-626510 (Gilead-Science-Inc.) against primary WES CC-cultures and CC-xenografts.

Experimental Design: HUWE1 and c-MYC expression were evaluated by qRT-PCR in a total of 23 CC including 12 fresh frozen tumor tissues and 11 primary cell lines. c-MYC expression was also evaluated by Western-Blot (WB) and fluorescence in situ hybridization (FISH) experiments in all 11 fully sequenced primary CC cell lines. Primary tumors were evaluated for sensitivity to GS-626510 in-vitro using proliferation and viability-assays. siRNA experiments were used to evaluate the effect of HUWE1 silencing on primary CC cell line growth and sensitivity to GS-626510. Finally, the in-vivo activity of GS-626510 was studied in CC-CVX8 mouse-xenografts.

Results: Fresh-frozen CC and primary CC cell lines overexpressed c-MYC when compared to normal control tissues (mean ± SEM mRNA values = 7.06 ± 1.17 vs a mean ± SEM = 2.96 ± 0.97, p = 0.01). FISH experiments demonstrated amplification of c-MYC in 9 out of 11 (82%) of the primary CC cell lines. Primary CC cell lines with derangements in the HUWE1/c-MYC pathway were highly sensitive to GS-626510, with a dose-response decrease in cell proliferation and IC50 values ranging from 3 to 57 nM. Silencing of HUWE1 by siRNA significantly increased c-MYC expression as well as CC cell proliferation and enhanced the in vitro sensitivity to GS-626510. Twice daily oral doses of GS-626510 (10 mg/kg) were well tolerated in vivo in animals and highly effective in decreasing tumor-growth (p = 0.004) and increasing survival (p value = 0.004) of mice harboring CC-CVX8 xenografts.

Conclusions: Downregulation/inactivation of HUWE1 may increase c-MYC expression and proliferation in primary CC cell lines. GS-626510 may represent a novel, potentially highly effective therapeutic agent against CC overexpressing c-MYC and/or harboring HUWE1 mutations. Clinical studies with BET inhibitor in CC-patients harboring radiation/chemotherapy-resistant disease are warranted.

Citation Format: Elena Bonazzoli, Stefania Bellone, Luca Zammataro, Barbara Gnutti, Adele Guglielmi, Silvia Pelligra, Paola Manara, Joan Tymon-Rosario, Burak Zeybek, Chanhee Han, Alessandro D. Santin. Derangements in HUWE1/c-MYC pathway confer sensitivity to the BET bromodomain inhibitor GS-626510 in uterine cervical carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5341.

Derangements in HUWE1/c-MYC pathway confer sensitivity to the BET bromodomain inhibitor GS-626510 in uterine cervical carcinoma

OBJECTIVE

Whole-exome-sequencing (WES) studies reported c-MYC gene-amplification and HUWE1 gene deletion/mutations in a significant number of cervical-cancer-patients (CC) suggesting HUWE1/c-MYC pathway as potential therapeutic target. We investigated HUWE1/c-MYC expression in fresh-frozen-CC and the activity of the novel BET inhibitor GS-626510 (Gilead-Science-Inc) against primary WES CC-cultures and CC-xenografts.

METHODS

HUWE1 and c-MYC expression were evaluated by qRT-PCR in 23 CC including 12 fresh-frozen-tumor-tissues and 11 primary-cell-lines. c-Myc expression was also evaluated by Western-Blot (WB) and fluorescence-in-situ-hybridization (FISH) in all 11 fully sequenced primary-CC-cell-lines. Primary tumors were evaluated for sensitivity to GS-626510 in-vitro using proliferation and viability-assays. siRNA experiments were used to evaluate the effect of HUWE1 silencing on primary-CC-cell-line growth and sensitivity to GS-626510. Finally, the in-vivo activity of GS-626510 was studied in CC-CVX8-mouse-xenografts.

RESULTS

Fresh-frozen-CC and primary-CC-cell-lines overexpressed c-MYC when compared to normal tissues (p = .01). FISH demonstrated amplification of c-MYC in 9/11 (82%) of the primary-CC-cell-lines. Cell-lines with derangements in HUWE1/c-MYC pathway were highly sensitive to GS-626510, with a dose-response decrease in cell proliferation and viability. siRNA silencing of HUWE1 significantly increased c-MYC expression and CC cell-proliferation and enhanced the in-vitro sensitivity to GS-626510. Twice-daily oral doses of GS-626510 were well tolerated in-vivo and highly effective in decreasing tumor-growth (p = .004) and increasing survival (p = .004) of CC-CVX8 xenografts.

CONCLUSIONS

Downregulation/inactivation of HUWE1 may increase c-MYC expression and proliferation in primary-CC-cell-lines. GS-626510 may represent a novel, potentially highly effective therapeutic agent against CC overexpressing c-MYC and/or harboring HUWE1 mutations. Clinical studies with BET inhibitor in CC-patients harboring radiation/chemotherapy-resistant disease are warranted.

P0074EXPANDING THE VARIABILITY OF THE ADPKD-GANAB CLINICAL PHENOTYPE: A NEW FAMILY OF ITALIAN ANCESTRY

Background and Aims

Causative GANAB mutations have been described in only 123 families, 98 diagnosed with late-onset mild ADPKD and 35 with ADPLD. We describe a new family with mild, late-onset ADPKD due to p. R839W GANAB mutation, previously reported in an ADPLD patient requiring liver transplantation.

Method

Mutation analysis of PKD1, PKD2, GANAB genes was performed by targeted NGS analysis. To analyze GANAB gene we developed a custom panel of 11 kidney cystogenes (GANAB, PKDH1, TSC1, TSC2, UMOD, HNF1B, REN, OFD1, PARN, DNAJB11, SEC61A1) designed using Ion Ampliseq Designer. Sanger sequencing was performed in order to validate all the variants classified as pathogenic, likely pathogenic and VUS. Raw sequence data analysis, including base calling, demultiplexing, alignment to the hg19 human reference genome, was performed using the Torrent Suite Software version 5.5; the average depth of total coverage was set at 500X and for variant calls at minimum of 30X. Deletion and duplication analysis of PKD1 and PKD2 was performed using MLPA P351-C1 and P352-D1 probemixes, MRC-Holland.

Results

Diagnosis of ADPKD was made in a 45-year old man during pre-surgical screening for umbilical and inguinal hernia repair. The patient's clinical course was characterized by several complications pertaining to the ADPKD spectrum: nephrolithiasis (20 yo); umbilical/bilateral inguinal hernia repair, hypertension and mild aortic root dilation (45 yo) and AKI due to ureteral obstruction (50 yo). Abdomen CT scan showed bilateral renal cysts (TKV 565 cc), nephrolithiasis, normal-sized liver with multiple cysts, and sigmoid colon diverticulosis. Renal function was normal (SCr 0.69 mg/dL, CKD-EPI 115 ml/min). In the index case, NGS and MLPA analysis of PKD1 and PKD2 genes did not detect variants. We then use the abovementioned multigene NGS panel and identified a missense heterozygous c.2515C&gt;T (p.R839W) variant in the GANAB gene. Screening was then extended to family members. No family members displayed renal function impairment. Both the 80 yo mother and the 84 yo father were found to have multiple bilateral kidney cysts (HtTKV of 239 ml and 435 ml, respectively), no liver cysts were found in either of them. Parents segregation analysis identified the GANAB variant p.R839W in the mother and in the maternal aunt. The father tested negative for all the abovementioned cystogenes.

Conclusion

we confirm that the renal phenotype caused by mutations in GANAB is very different from those due to mutations in PKD1 and PKD2, giving rise to a mild form of renal cystic disease, usually not progressing to ESRD. Despite the mild renal cystic burden, the index case showed a plethora of renal and extrarenal manifestations of ADPKD. The finding that patients with GANAB mutation can present with renal and liver cystic phenotype is intriguing, indicating a commonality between pathogenic background of two different inherited disorders, ADPKD and ADPLD. The missense GANAB mutation identified in our ADPKD family was first described in a pedigree reported by Porath et al. and diagnosed as ADPLD. This suggests that, beyond the effect of the shared mutation on GII subunit α, other modifier loci and environmental factors may influence the course of liver disease development and progression. Our study illustrates the important diagnostic role of a broader genetic testing, able to screen not only for PKD1 and PKD2 variants, but also for pathogenic variants in other cystogenes.

Autosomal Dominant Tubulointerstitial Kidney Disease with Adult Onset due to a Novel Renin Mutation Mapping in the Mature Protein

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a genetically heterogeneous renal disorder leading to progressive loss of renal function. ADTKD-REN is due to rare mutations in renin, all localized in the protein leader peptide and affecting its co-translational insertion in the endoplasmic reticulum (ER). Through exome sequencing in an adult-onset ADTKD family we identified a new renin variant, p.L381P, mapping in the mature protein. To assess its pathogenicity, we combined genetic data, computational and predictive analysis and functional studies. The L381P substitution affects an evolutionary conserved residue, co-segregates with renal disease, is not found in population databases and is predicted to be deleterious by in silico tools and by structural modelling. Expression of the L381P variant leads to its ER retention and induction of the Unfolded Protein Response in cell models and to defective pronephros development in zebrafish. Our work shows that REN mutations outside of renin leader peptide can cause ADTKD and delineates an adult form of ADTKD-REN, a condition which has usually its onset in childhood. This has implications for the molecular diagnosis and the estimated prevalence of the disease and points at ER homeostasis as a common pathway affected in ADTKD-REN, and possibly more generally in ADTKD.