Table 1.

Cr(VI)-induced effects on the expression and activity of components of the stress response.

Protein Family	System 1	Exposure Regime		Effect 3	Study
		Cr(VI) Dose/Concentration 2	Duration
Small HSP	Rat lung epithelial cells	10 µM	24 h	Increased HSP10 protein levels	[42]
	HaCaT cells	7.4 µM	24 h	Increased HSP27 (HSPB1) mRNA and protein levels; Reduced HSP27 (HSPB1) phosphorylation	[43]
	Human primary skin fibroblasts	1 µM	16 h	Increased protein levels of phosphorylated HSP27	[44]
	BNL CL.2 cells	15 µM	3 h	Increased liver HSP27 protein levels	[45]
	ICR mice	10 mg/kg body weight (intraperitoneal injection)	8 weeks
	BEAS-2B cells	10 µM	4 h	Unchanged HSP27 (HSPB1) mRNA levels	[46]
Hsp40	BEAS-2B cells	10 µM	4 h	Decreased HSP40 mRNA levels	[46]
HSP60	BEAS-2B cells		4 h	Decreased HSP60 (HSPD1) mRNA levels
	Rat lung epithelial cells		24 h	Increased HSP60 protein levels	[42]
HSP70	BEAS-2B cells	1 µM	48 h	Unchanged Hsp72 (HSPA1A) protein levels; Decreased Hsp72 (HSPA1A) mRNA levels	[47]
		10 µM	4 h	Unchanged HSP70 (HSPA6), HSP70.1 (HSPA1) and HSP71 (HSPA8) mRNA levels	[46]
	Sprague-Dawley rats	0.25 mg/kg body weight (intratracheal instillation)	3 days	HSP70 mRNA levels increased in the lungs and unchanged in the liver; Unchanged HSP60, Grp75 and Grp94 mRNA levels in both lungs and liver	[48]
	HT29	10 or 50 µM	6 h	Increased Hsp72 (HSPA1A) mRNA levels	[49]
	HepG2 cells	0.5 or 1 µM
		0.625–10 µM	48 h	Induction of HSP70 and Grp78 (HSPA5) promoters for [Cr(VI)] ≥ 5 µM	[50]
		100 µM	3 h	Unchanged HSP70 mRNA levels	[51]
	Primary culture of rat granulosa cells	10 µM	12 or 24 h	Decreased HSP70 protein levels	[52]
	L-02 cells	16 or 32 µM	24 h	Decreased HSP70 proteins levels	[53]
		8 or 16 µM	24 h	Increased Grp78 (HSPA5) mRNA levels	[54]
	BNL CL.2 cells	15 µM	3 h	Increased liver HSP70 protein levels	[45]
	ICR mice	10 mg/kg body weight (intraperitoneal injection)	8 weeks
	A549	0.5 µM	2–24 h	Increased Grp78 (HSPA5) protein levels	[55]
HSP90	BEAS-2B cells	1 µM	48 h	Decreased Hsp90α (HSPC1) protein levels. Unchanged Hsp90α (HSPC1) mRNA levels	[47]
		10 µM	4 h	Decreased HSP90A (HSPC1) mRNA levels	[46]
	Primary culture of rat granulosa cells		12 or 24 h	Decreased HSP90 protein levels	[52]
	L-02 cells	16 or 32 µM	24 h	Decreased HSP90 protein levels	[53]
	A549	600 µM	2 h	Increased TRAP1 (HSPC5) mRNA levels	[56]
HSP100	Rat lung epithelial cells	10 µM	24 h	Increased HSP105 protein levels	[42]

¹ A549, cell line established from a human lung adenocarcinoma; BEAS-2B, cell line established from human bronchial epithelium; BNL CL.2, cell line established from embryonic murine liver tissue; HaCaT, keratinocytes cell line established from human skin; HepG2, cell line established from a human hepatocellular carcinoma; HT29, cell line established from a human colorectal adenocarcinoma; L-02, cell line established from human embryonic liver tissue. ² Cr(VI) was added as a K₂Cr₂O₇ or Na₂CrO₄ aqueous solution. Of note, for several studies, Cr(VI) concentration values are ambiguous, as the expressions “x μM Cr(VI)” and “x μM potassium dichromate” were used indistinguishably, even though a given potassium dichromate concentrations corresponds to a Cr(VI) concentration twice that value. ³ For designations, see Section 3.1.