$C_1:\ a^2b^2(a-b)+b^2c^2(b-c)+a^2c^2(c-a)\\
= a^2b^2(a-b)+b^3c^2-b^2c^3+a^2c^3-a^3c^2\\
=a^2b^2(a-b)-c^2(a^3-b^3)+c^3(a^2-b^2)\\
=a^2b^2(a-b)-c^2(a-b)(a^2+ab+b^2)+c^3(a-b)(a+b)\\
=(a-b)(a^2b^2-a^2c^2-abc^2-b^2c^2+ac^3+bc^3\\
=(a-b)[a^2(b^2-c^2)-ac^2(b-c)-bc^2(b-c)]\\
=(a-b)(b-c)(a^2b+a^2c-ac^2-bc^2)\\
=(a-b)(b-c)[b(a^2-c^2)+ac(a-c)]\\
=(a-b)(b-c)(a-c)(ab+bc+ac)$
$C_2:\ a^2b^2(a-b)+b^2c^2(b-c)+a^2c^2(c-a)\\
=a^2b^2(a-b)+b^2c^2[-(a-b)-(c-a)]+a^2c^2(c-a)\\
=a^2b^2(a-b)-b^2c^2(a-b)-b^2c^2(c-a)+a^2c^2(c-a)\\
=(a-b)(a^2b^2-b^2c^2)+(c-a)(a^2c^2-b^2c^2)\\
=(a-b)[-b^2(c^2-a^2)]+(c-a)[c^2(a^2-b^2)]\\
=(a-b)(c-a)[-b^2(c+a)+c^2(a+b)]\\
=(a-b)(c-a)(-b^2c-ab^2+ac^2+bc^2)\\
=(a-b)(c-a)[a(c^2-b^2)+bc(c-b)]\\
=(a-b)(c-a)(c-b)(ac+ab+bc)$