Table 3.

Drugs, their mode of action, and reported effects on GJIC and breast tumor.

Drug	Mode of action	Anti-breast tumor effect
Organochlorine compound TCDD	Nonspecific, increases phosphorylated Cx43 and GJIC	Decreases GJIC
PQ1 quinolone derivative	Nonspecific, increases Cx43 expression and increases GJIC	Decreases colony formation ability and xenograft tumor growth of T47D cells
PQ1 + cisplatin	Combination treatment, bystander effect	Reduces T47D cell proliferation synergizing with cytotoxic effects of cisplatin
Peptide ACT1	Increases gap junction aggregation by redirecting uncoupled Cx43 hemichannels into the membrane	Reduces MCF-7 and MDA-MB-231 cell proliferation in vitro
ACT1 + tamoxifen	Combination treatment, bystander effect	Augments tamoxifen cytotoxic effects on MCF-7 cells
All-trans-retinoic acid (ATRA) + VEGFP-TK/CD gene suicide system	ATRA increases GJIC and mediates bystander effects to induce cell killing by gene suicide system	Increases apoptotic MCF-7 cell death
Anti-Cx46	Knocks down Cx46	Reduces MCF-7 viability under hypoxia and inhibits xenograft tumor growth