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. 2016 Aug 20;7(51):84093–84117. doi: 10.18632/oncotarget.11455

Figure 6. Effect of overexpression of HERV-K on in vitro migration, invasion, and transformation in cancer cells.

Figure 6

Significantly decreased migration (p < 0.0001; (A, top right) and invasion (p < 0.0001; A, bottom right) of MCF-7 cells stably transduced with shRNAenv was observed, compared with cells transduced with a scrambled shRNAc vector. Migration and invasion was increased if shRNAc cells were transduced with an HERV-K env expression vector [+Kenv; p = 0.0482 for migration (A, top right) and p = 0.0427 for invasion (A, bottom right)] or a vector expressing a mutated env gene [+Kmut; p = 0.0395 for migration (A, top right) and p = 0.0394 for invasion (A, bottom right) (n = 11; unpaired t test)]. Untreated and vector only (+pLVX) were used as controls. No significant change was observed in shRNAenv cells transduced with Kenv, likely due to continued shRNAenv knockdown in these cells even in the presence of higher levels of Kenv. Significant change was observed in shRNAenv cells transduced with Kmut for migration (p = 0.0016) and invasion (p = 0.0394). Anchorage-independent growth assays were employed to determine cell transformation after BC cells were transduced with HERV-K env or mutated env gene. Images were taken 2 weeks post-seeding of cells in soft agar. Larger colonies and significantly increased numbers of colonies were observed for shRNAc cells after transduction with Kenv or Kmut in MCF-7 shRNAc (p = 0.001 and p = 0.016, respectively; Figure B), Hs578T shRNAc (p = 0.0086 and p = 0.025, respectively; Figure C), and MDA-MB-231 (p = 0.0002 and p = 0.036, respectively; Figure D) cells. Significantly increased numbers of colonies were observed for shRNAenv cells transduced with Kmut in MCF-7 (B: p = 0.001), Hs578T (C; p < 0.0001), and MDA-MB-231 (D; p = 0.002) cells (n = 4; unpaired t test). (E) Immunoblot assays showed increased levels of HIF-1alpha, p-RSK, HERV-K, p-ERK 1 or 2, and Ras protein in MCF-7 shRNAc cells transduced with Kenv or Kmut and in MCF-7 shRNAenv cells transduced with Kmut. The deviation (error bars) represents standard error of the mean (SEM).