Mouse xenograft experiments

JHU029 cells (1 × 10⁶) containing 40% Matrigel were injected subcutaneously into the flank of BALB/c athymic nude mice (7–8 weeks old). When the palpable tumor was developed (~ 70–80 mm³), mice were divided into two groups randomly. Ten microgram of siELDR or control oligo complexed with siPORTamine (Invitrogen) in 50 μl Opti‐MEM was injected intratumorally at an interval of 4 days as described previously (Sur et al, 2019b). Body weight was monitored, and tumor size was measured using a slide Caliper and volume was calculated using the formula ½ L × W ². All the mice were sacrificed after 6^th week of tumor cell injection. After sacrifice tumors were dissected out and snap frozen in liquid nitrogen for RNA and protein isolation.

Cryopreserved OSCC patient‐derived xenograft (PDX) sample (sample# MD0944; Tumor model# 832693‐133‐R; passage 3) was obtained from the NCI Patient‐Derived Models Repository (PDMR), NCI‐Frederick, Frederick National Laboratory for Cancer Research, Frederick, MD (https://pdmr.cancer.gov/). The tissue was fragmented into pieces and implanted subcutaneously into flank of 10 NSG mice. Tumor‐bearing mice were divided into two groups randomly. Tumor take was 100% in our hands. Control or siELDR (10 μg) were injected intratumorally at an interval of 4 days. Tumor volume was measured as described above. After sacrifice tumors were dissected out and snap frozen in liquid nitrogen for further analysis. All the animal experiments were carried out in accordance NIH guidelines, following a protocol approved by the Institutional Animal Care and Use Committee (IACUC) of the Saint Louis University.