Abstract 2482: On the verge of metastasis: CTH defines a cell-state-dependent adaptive response to microenvironmental stresses

Introduction: Clear cell carcinoma of the ovary (CCC) is the 2nd most common ovarian cancer and is histologically and clinically distinct from other subtypes. Late stage CCC have a worse prognosis than other ovarian cancer histotypes as they are inherently resistant to the standard platinum/taxane chemotherapy. Deep endometriosis of the ovary, known as endometrioma or chocolate cyst, is the most common precursor for CCC. However, how transformation from endometriosis to CCC and, in particular, the important role of the hypoxic and ROS-rich microenvironment of endometriotic cysts are not well understood. As the molecular mechanisms pertinent to the genesis and progression of CCC are largely unknown, there are few, if any, therapeutic strategies for patients with advanced stage disease. Identifying factors that shape the development, progression and metastasis of CCC which can be targeted therapeutically could have tremendous potential to improve outcomes in this disease. Our recent findings identified cystathionine gamma-lyase (CTH), a key enzyme in the transsulfuration pathway, as a marker of Mullerian tract derived ciliated cells and CCC of both the ovary and uterus regardless of which mutations are present. Also, CTH is highly expressed both in CCC and the endometriosis adjacent to this cancer. Whether and how the transsulfuration pathway, notably CTH, enables CCC to adapt to the hostile microenvironment of an endometriotic cyst and ultimately to promote metastasis remain unanswered.

Methods: We generated CTH knockout (KO) cells using CRISPR/Cas9. We assessed effects of CTH loss in vitro -under ambient and stress conditions- and in vivo on cell viability, cell proliferation, ROS levels, migration, invasion, and metastasis. Further, we used an organoid model system to assess the impact of CTH loss in primary endometrial cells on organoid growth and response to stress conditions including exposure to endometriotic cyst contents.

Results: Our in-vitro, in-vivo data as well as data derived from the organoid modelling system show that CTH is critical for adaptive response to hypoxia. Further, it underpins the growth of CCC cells in-vitro and the growth of CTH in a mouse model of CCC. These data highly indicate that expression of the transsulfuration pathway enzyme CTH enables cells to survive in endometriotic cysts then upon transformation both marks CCC and potentiates tumor progression and metastasis.

Conclusion: Targeting CTH in CCC and potentially other cancers might represent a novel and impactful therapeutic approach.

Citation Format: Amal M. El-Naggar, Yuchen Ding, Genny Trigo-Gonzalez, Lucy Li, Shary Chen, Busra Turgu, Forouh Kalantari, Rodrigo Vallejos, Kiran Parmar, Cindy Shen, Gian Luca Negri, Paul Yong, Gregg Morin, David G. Huntsman. On the verge of metastasis: CTH defines a cell-state-dependent adaptive response to microenvironmental stresses [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 2482.

Two-stage esophagojejunal anastomosis: An alternative reconstruction in emergency gastrectomy for high-risk gastric cancer patients

Emergency total gastrectomy for patients with gastric cancer who are in shock carries a high risk of esophagojejunal anastomosis leakage. No alternatives have been reported to reduce this risk. This study reports two patients with gastric cancer who were in shock and underwent emergency gastrectomy and two-stage esophagojejunal anastomosis with good results. In the first stage, immediately after gastrectomy, the esophagus was attached to a Roux-en-Y jejunal loop that prevented retraction of the esophagus into the mediastinum. In the second stage, in a second surgery, the esophagojejunal anastomosis was completed under better clinical conditions.

Outcome after laparoscopic enucleation for non-functional neuroendocrine pancreatic tumours

BACKGROUND

Non-functional endocrine pancreatic tumours (NPT) of more than 2 cm have an increased risk of malignancy. The aim of the present study was: (i) to define the guidelines for laparoscopic enucleation (LapEn) in patients with a non-functional NPT ≤3 cm in diameter; (ii) to evaluate pancreas-related complications; and (iii) to present the long-term outcome.

METHODS

Between April 1998 and September 2010, 30 consecutive patients underwent laparoscopic surgery for a non-functional NPT (median age 56.5 years, range 44-83). Only 13 patients with tumours ≤3 cm in size underwent LapEn. Local lymph node dissection to exclude lymph node involvement was performed in all patients.

RESULTS

The median tumour size, operative time and blood loss were 2.8 cm (range 2.8-3), 130 min (range 90-280) and 220 ml (range 120-300), respectively. A pancreatic fistula occurred in five patients: International Study Group of Pancreatic Fistula (ISGPF) A in two patients and ISGPF B in three patients. The median follow-up was 48 months (12-144). Three patients with well-differentiated carcinoma are free of disease 2, 3 and 4 years after LapEn and a regional lymphadenectomy. One patient, 5 years after a LapEn, presented with lymph node and liver metastases.

CONCLUSIONS

The present study confirms the technical feasibility and acceptable morbidity associated with LapEn. Intra-operative lymph node sampling and frozen-section examination should be performed at the time of LapEn; when a malignancy is confirmed, oncologically appropriate lymph node dissection should be performed.

Effect of oxygen pressure on glycogen synthesis by rat-liver slices

1. Glycogen synthesized by rat-liver slices 0.5mm. thick incubated at 1atm. oxygen pressure in Hastings medium with glucose was localized in the cells of the periphery of the slice. Cells of the interior of this slice do not synthesize glycogen. 2. Inner cells of thin slices (about 0.3mm. thick) can synthesize glycogen when such slices are incubated under the same conditions, but oxygen pressures higher than 1atm. are required if inner cells of slices 0.5mm. or more thick are to be able to synthesize glycogen. 3. Localization of newly synthesized glycogen in rat-liver slices incubated in Hastings medium with glucose does not depend on glucose concentration. 4. Calculation of the minimum oxygen pressure required to synthesize glycogen gives values between 0.09 and 0.17atm. 5. The advantages of high oxygen pressures for the study of the synthesis of glycogen and other compounds that require ATP are discussed.